€•3      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ-/translations/zh_CN/filesystems/sharedsubtree”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/zh_TW/filesystems/sharedsubtree”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/it_IT/filesystems/sharedsubtree”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/ja_JP/filesystems/sharedsubtree”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/ko_KR/filesystems/sharedsubtree”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/sp_SP/filesystems/sharedsubtree”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ SPDX-License-Identifier: GPL-2.0”h]”hŒ SPDX-License-Identifier: GPL-2.0”…””}”hh£sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1h¡hhhžhhŸŒG/var/lib/git/docbuild/linux/Documentation/filesystems/sharedsubtree.rst”h KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒShared Subtrees”h]”hŒShared Subtrees”…””}”(hh»hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh¶hžhhŸh³h Kubh¢)”}”(hŒ|Contents:
1) Overview
2) Features
3) Setting mount states
4) Use-case
5) Detailed semantics
6) Quiz
7) FAQ
8) Implementation”h]”hŒ|Contents:
1) Overview
2) Features
3) Setting mount states
4) Use-case
5) Detailed semantics
6) Quiz
7) FAQ
8) Implementation”…””}”hhÉsbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1h¡hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒ1) Overview”h]”hŒ1) Overview”…””}”(hhÚhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh×hžhhŸh³h KubhŒ	paragraph”“”)”}”(hŒ!Consider the following situation:”h]”hŒ!Consider the following situation:”…””}”(hhêhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Khh×hžhubhé)”}”(hŒºA process wants to clone its own namespace, but still wants to access the CD
that got mounted recently.  Shared subtree semantics provide the necessary
mechanism to accomplish the above.”h]”hŒºA process wants to clone its own namespace, but still wants to access the CD
that got mounted recently.  Shared subtree semantics provide the necessary
mechanism to accomplish the above.”…””}”(hhøhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Khh×hžhubhé)”}”(hŒhIt provides the necessary building blocks for features like per-user-namespace
and versioned filesystem.”h]”hŒhIt provides the necessary building blocks for features like per-user-namespace
and versioned filesystem.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Khh×hžhubeh}”(h]”Œoverview”ah ]”h"]”Œ1) overview”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒ2) Features”h]”hŒ2) Features”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj  hžhhŸh³h Kubhé)”}”(hŒWShared subtree provides four different flavors of mounts; struct vfsmount to be
precise”h]”hŒWShared subtree provides four different flavors of mounts; struct vfsmount to be
precise”…””}”(hj-  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K!hj  hžhubhŒblock_quote”“”)”}”(hŒEa. shared mount
b. slave mount
c. private mount
d. unbindable mount

”h]”hŒenumerated_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒshared mount”h]”hé)”}”(hjJ  h]”hŒshared mount”…””}”(hjL  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K$hjH  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjC  ubjG  )”}”(hŒslave mount”h]”hé)”}”(hja  h]”hŒslave mount”…””}”(hjc  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K%hj_  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjC  ubjG  )”}”(hŒprivate mount”h]”hé)”}”(hjx  h]”hŒprivate mount”…””}”(hjz  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K&hjv  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjC  ubjG  )”}”(hŒunbindable mount

”h]”hé)”}”(hŒunbindable mount”h]”hŒunbindable mount”…””}”(hj‘  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K'hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjC  ubeh}”(h]”h ]”h"]”h$]”h&]”Œenumtype”Œ
loweralpha”Œprefix”hŒsuffix”Œ.”uh1jA  hj=  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h K$hj  hžhubhé)”}”(hŒm2a) A shared mount can be replicated to as many mountpoints and all the
replicas continue to be exactly same.”h]”hŒm2a) A shared mount can be replicated to as many mountpoints and all the
replicas continue to be exactly same.”…””}”(hj¶  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K*hj  hžhubj<  )”}”(hXî  Here is an example:

Let's say /mnt has a mount that is shared::

    mount --make-shared /mnt

Note: mount(8) command now supports the --make-shared flag,
so the sample 'smount' program is no longer needed and has been
removed.

::

    # mount --bind /mnt /tmp

The above command replicates the mount at /mnt to the mountpoint /tmp
and the contents of both the mounts remain identical.

::

    #ls /mnt
    a b c

    #ls /tmp
    a b c

Now let's say we mount a device at /tmp/a::

    # mount /dev/sd0  /tmp/a

    #ls /tmp/a
    t1 t2 t3

    #ls /mnt/a
    t1 t2 t3

Note that the mount has propagated to the mount at /mnt as well.

And the same is true even when /dev/sd0 is mounted on /mnt/a. The
contents will be visible under /tmp/a too.

”h]”(hé)”}”(hŒHere is an example:”h]”hŒHere is an example:”…””}”(hjÈ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K-hjÄ  ubhé)”}”(hŒ+Let's say /mnt has a mount that is shared::”h]”hŒ,Letâ€™s say /mnt has a mount that is shared:”…””}”(hjÖ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K/hjÄ  ubhŒliteral_block”“”)”}”(hŒmount --make-shared /mnt”h]”hŒmount --make-shared /mnt”…””}”hjæ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h K1hjÄ  ubhé)”}”(hŒ„Note: mount(8) command now supports the --make-shared flag,
so the sample 'smount' program is no longer needed and has been
removed.”h]”hŒˆNote: mount(8) command now supports the --make-shared flag,
so the sample â€˜smountâ€™ program is no longer needed and has been
removed.”…””}”(hjô  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K3hjÄ  ubjå  )”}”(hŒ# mount --bind /mnt /tmp”h]”hŒ# mount --bind /mnt /tmp”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h K9hjÄ  ubhé)”}”(hŒ{The above command replicates the mount at /mnt to the mountpoint /tmp
and the contents of both the mounts remain identical.”h]”hŒ{The above command replicates the mount at /mnt to the mountpoint /tmp
and the contents of both the mounts remain identical.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K;hjÄ  ubjå  )”}”(hŒ#ls /mnt
a b c

#ls /tmp
a b c”h]”hŒ#ls /mnt
a b c

#ls /tmp
a b c”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h K@hjÄ  ubhé)”}”(hŒ+Now let's say we mount a device at /tmp/a::”h]”hŒ,Now letâ€™s say we mount a device at /tmp/a:”…””}”(hj,  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KFhjÄ  ubjå  )”}”(hŒB# mount /dev/sd0  /tmp/a

#ls /tmp/a
t1 t2 t3

#ls /mnt/a
t1 t2 t3”h]”hŒB# mount /dev/sd0  /tmp/a

#ls /tmp/a
t1 t2 t3

#ls /mnt/a
t1 t2 t3”…””}”hj:  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h KHhjÄ  ubhé)”}”(hŒ@Note that the mount has propagated to the mount at /mnt as well.”h]”hŒ@Note that the mount has propagated to the mount at /mnt as well.”…””}”(hjH  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KPhjÄ  ubhé)”}”(hŒlAnd the same is true even when /dev/sd0 is mounted on /mnt/a. The
contents will be visible under /tmp/a too.”h]”hŒlAnd the same is true even when /dev/sd0 is mounted on /mnt/a. The
contents will be visible under /tmp/a too.”…””}”(hjV  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KRhjÄ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h K-hj  hžhubhŒdefinition_list”“”)”}”(hhh]”hŒdefinition_list_item”“”)”}”(hX?  2b) A slave mount is like a shared mount except that mount and umount events
only propagate towards it.

All slave mounts have a master mount which is a shared.

Here is an example:

Let's say /mnt has a mount which is shared.
# mount --make-shared /mnt

Let's bind mount /mnt to /tmp
# mount --bind /mnt /tmp

the new mount at /tmp becomes a shared mount and it is a replica of
the mount at /mnt.

Now let's make the mount at /tmp; a slave of /mnt
# mount --make-slave /tmp

let's mount /dev/sd0 on /mnt/a
# mount /dev/sd0 /mnt/a

#ls /mnt/a
t1 t2 t3

#ls /tmp/a
t1 t2 t3

Note the mount event has propagated to the mount at /tmp

However let's see what happens if we mount something on the mount at /tmp

# mount /dev/sd1 /tmp/b

#ls /tmp/b
s1 s2 s3

#ls /mnt/b

Note how the mount event has not propagated to the mount at
/mnt

”h]”(hŒterm”“”)”}”(hŒL2b) A slave mount is like a shared mount except that mount and umount events”h]”hŒL2b) A slave mount is like a shared mount except that mount and umount events”…””}”(hjw  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Khjq  ubhŒ
definition”“”)”}”(hhh]”(hé)”}”(hŒonly propagate towards it.”h]”hŒonly propagate towards it.”…””}”(hjŠ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KWhj‡  ubhé)”}”(hŒ7All slave mounts have a master mount which is a shared.”h]”hŒ7All slave mounts have a master mount which is a shared.”…””}”(hj˜  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KYhj‡  ubhé)”}”(hŒHere is an example:”h]”hŒHere is an example:”…””}”(hj¦  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K[hj‡  ubhé)”}”(hŒFLet's say /mnt has a mount which is shared.
# mount --make-shared /mnt”h]”hŒHLetâ€™s say /mnt has a mount which is shared.
# mount --make-shared /mnt”…””}”(hj´  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K]hj‡  ubhé)”}”(hŒ6Let's bind mount /mnt to /tmp
# mount --bind /mnt /tmp”h]”hŒ8Letâ€™s bind mount /mnt to /tmp
# mount --bind /mnt /tmp”…””}”(hjÂ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K`hj‡  ubhé)”}”(hŒVthe new mount at /tmp becomes a shared mount and it is a replica of
the mount at /mnt.”h]”hŒVthe new mount at /tmp becomes a shared mount and it is a replica of
the mount at /mnt.”…””}”(hjÐ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kchj‡  ubhé)”}”(hŒKNow let's make the mount at /tmp; a slave of /mnt
# mount --make-slave /tmp”h]”hŒMNow letâ€™s make the mount at /tmp; a slave of /mnt
# mount --make-slave /tmp”…””}”(hjÞ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kfhj‡  ubhé)”}”(hŒ6let's mount /dev/sd0 on /mnt/a
# mount /dev/sd0 /mnt/a”h]”hŒ8letâ€™s mount /dev/sd0 on /mnt/a
# mount /dev/sd0 /mnt/a”…””}”(hjì  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kihj‡  ubhé)”}”(hŒ#ls /mnt/a
t1 t2 t3”h]”hŒ#ls /mnt/a
t1 t2 t3”…””}”(hjú  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Klhj‡  ubhé)”}”(hŒ#ls /tmp/a
t1 t2 t3”h]”hŒ#ls /tmp/a
t1 t2 t3”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kohj‡  ubhé)”}”(hŒ8Note the mount event has propagated to the mount at /tmp”h]”hŒ8Note the mount event has propagated to the mount at /tmp”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Krhj‡  ubhé)”}”(hŒIHowever let's see what happens if we mount something on the mount at /tmp”h]”hŒKHowever letâ€™s see what happens if we mount something on the mount at /tmp”…””}”(hj$  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kthj‡  ubhé)”}”(hŒ# mount /dev/sd1 /tmp/b”h]”hŒ# mount /dev/sd1 /tmp/b”…””}”(hj2  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kvhj‡  ubhé)”}”(hŒ#ls /tmp/b
s1 s2 s3”h]”hŒ#ls /tmp/b
s1 s2 s3”…””}”(hj@  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kxhj‡  ubhé)”}”(hŒ
#ls /mnt/b”h]”hŒ
#ls /mnt/b”…””}”(hjN  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K{hj‡  ubhé)”}”(hŒ@Note how the mount event has not propagated to the mount at
/mnt”h]”hŒ@Note how the mount event has not propagated to the mount at
/mnt”…””}”(hj\  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K}hj‡  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjq  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Khjl  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj  hžhhŸh³h Nubhé)”}”(hŒ<2c) A private mount does not forward or receive propagation.”h]”hŒ<2c) A private mount does not forward or receive propagation.”…””}”(hj|  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Khj  hžhubj<  )”}”(hŒ?This is the mount we are familiar with. Its the default type.

”h]”hé)”}”(hŒ=This is the mount we are familiar with. Its the default type.”h]”hŒ=This is the mount we are familiar with. Its the default type.”…””}”(hjŽ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KƒhjŠ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Kƒhj  hžhubhé)”}”(hŒ42d) A unbindable mount is a unbindable private mount”h]”hŒ42d) A unbindable mount is a unbindable private mount”…””}”(hj¢  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K†hj  hžhubj<  )”}”(hXV  let's say we have a mount at /mnt and we make it unbindable::

    # mount --make-unbindable /mnt

 Let's try to bind mount this mount somewhere else::

    # mount --bind /mnt /tmp
    mount: wrong fs type, bad option, bad superblock on /mnt,
            or too many mounted file systems

Binding a unbindable mount is a invalid operation.

”h]”(hé)”}”(hŒ=let's say we have a mount at /mnt and we make it unbindable::”h]”hŒ>letâ€™s say we have a mount at /mnt and we make it unbindable:”…””}”(hj´  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kˆhj°  ubjå  )”}”(hŒÜ   # mount --make-unbindable /mnt

Let's try to bind mount this mount somewhere else::

   # mount --bind /mnt /tmp
   mount: wrong fs type, bad option, bad superblock on /mnt,
           or too many mounted file systems”h]”hŒÜ   # mount --make-unbindable /mnt

Let's try to bind mount this mount somewhere else::

   # mount --bind /mnt /tmp
   mount: wrong fs type, bad option, bad superblock on /mnt,
           or too many mounted file systems”…””}”hjÂ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h KŠhj°  ubhé)”}”(hŒ2Binding a unbindable mount is a invalid operation.”h]”hŒ2Binding a unbindable mount is a invalid operation.”…””}”(hjÐ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K’hj°  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Kˆhj  hžhubeh}”(h]”Œfeatures”ah ]”h"]”Œ2) features”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒ3) Setting mount states”h]”hŒ3) Setting mount states”…””}”(hjï  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjì  hžhhŸh³h K–ubj<  )”}”(hŒÛThe mount command (util-linux package) can be used to set mount
states::

    mount --make-shared mountpoint
    mount --make-slave mountpoint
    mount --make-private mountpoint
    mount --make-unbindable mountpoint

”h]”(hé)”}”(hŒHThe mount command (util-linux package) can be used to set mount
states::”h]”hŒGThe mount command (util-linux package) can be used to set mount
states:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K˜hjý  ubjå  )”}”(hŒmount --make-shared mountpoint
mount --make-slave mountpoint
mount --make-private mountpoint
mount --make-unbindable mountpoint”h]”hŒmount --make-shared mountpoint
mount --make-slave mountpoint
mount --make-private mountpoint
mount --make-unbindable mountpoint”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h K›hjý  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h K˜hjì  hžhubeh}”(h]”Œsetting-mount-states”ah ]”h"]”Œ3) setting mount states”ah$]”h&]”uh1h´hh¶hžhhŸh³h K–ubhµ)”}”(hhh]”(hº)”}”(hŒ4) Use cases”h]”hŒ4) Use cases”…””}”(hj.  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj+  hžhhŸh³h K¢ubj<  )”}”(hXŒ
  A) A process wants to clone its own namespace, but still wants to
   access the CD that got mounted recently.

   Solution:

        The system administrator can make the mount at /cdrom shared::

            mount --bind /cdrom /cdrom
            mount --make-shared /cdrom

        Now any process that clones off a new namespace will have a
        mount at /cdrom which is a replica of the same mount in the
        parent namespace.

        So when a CD is inserted and mounted at /cdrom that mount gets
        propagated to the other mount at /cdrom in all the other clone
        namespaces.

B) A process wants its mounts invisible to any other process, but
still be able to see the other system mounts.

   Solution:

        To begin with, the administrator can mark the entire mount tree
        as shareable::

            mount --make-rshared /

        A new process can clone off a new namespace. And mark some part
        of its namespace as slave::

            mount --make-rslave /myprivatetree

        Hence forth any mounts within the /myprivatetree done by the
        process will not show up in any other namespace. However mounts
        done in the parent namespace under /myprivatetree still shows
        up in the process's namespace.


Apart from the above semantics this feature provides the
building blocks to solve the following problems:

C)  Per-user namespace

        The above semantics allows a way to share mounts across
        namespaces.  But namespaces are associated with processes. If
        namespaces are made first class objects with user API to
        associate/disassociate a namespace with userid, then each user
        could have his/her own namespace and tailor it to his/her
        requirements. This needs to be supported in PAM.

D)  Versioned files

        If the entire mount tree is visible at multiple locations, then
        an underlying versioning file system can return different
        versions of the file depending on the path used to access that
        file.

        An example is::

            mount --make-shared /
            mount --rbind / /view/v1
            mount --rbind / /view/v2
            mount --rbind / /view/v3
            mount --rbind / /view/v4

        and if /usr has a versioning filesystem mounted, then that
        mount appears at /view/v1/usr, /view/v2/usr, /view/v3/usr and
        /view/v4/usr too

        A user can request v3 version of the file /usr/fs/namespace.c
        by accessing /view/v3/usr/fs/namespace.c . The underlying
        versioning filesystem can then decipher that v3 version of the
        filesystem is being requested and return the corresponding
        inode.
”h]”(jB  )”}”(hhh]”jG  )”}”(hX5  A process wants to clone its own namespace, but still wants to
access the CD that got mounted recently.

Solution:

     The system administrator can make the mount at /cdrom shared::

         mount --bind /cdrom /cdrom
         mount --make-shared /cdrom

     Now any process that clones off a new namespace will have a
     mount at /cdrom which is a replica of the same mount in the
     parent namespace.

     So when a CD is inserted and mounted at /cdrom that mount gets
     propagated to the other mount at /cdrom in all the other clone
     namespaces.
”h]”(hé)”}”(hŒgA process wants to clone its own namespace, but still wants to
access the CD that got mounted recently.”h]”hŒgA process wants to clone its own namespace, but still wants to
access the CD that got mounted recently.”…””}”(hjG  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K¤hjC  ubhé)”}”(hŒ	Solution:”h]”hŒ	Solution:”…””}”(hjU  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K§hjC  ubj<  )”}”(hX”  The system administrator can make the mount at /cdrom shared::

    mount --bind /cdrom /cdrom
    mount --make-shared /cdrom

Now any process that clones off a new namespace will have a
mount at /cdrom which is a replica of the same mount in the
parent namespace.

So when a CD is inserted and mounted at /cdrom that mount gets
propagated to the other mount at /cdrom in all the other clone
namespaces.
”h]”(hé)”}”(hŒ>The system administrator can make the mount at /cdrom shared::”h]”hŒ=The system administrator can make the mount at /cdrom shared:”…””}”(hjg  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K©hjc  ubjå  )”}”(hŒ5mount --bind /cdrom /cdrom
mount --make-shared /cdrom”h]”hŒ5mount --bind /cdrom /cdrom
mount --make-shared /cdrom”…””}”hju  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h K«hjc  ubhé)”}”(hŒ‰Now any process that clones off a new namespace will have a
mount at /cdrom which is a replica of the same mount in the
parent namespace.”h]”hŒ‰Now any process that clones off a new namespace will have a
mount at /cdrom which is a replica of the same mount in the
parent namespace.”…””}”(hjƒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K®hjc  ubhé)”}”(hŒ‰So when a CD is inserted and mounted at /cdrom that mount gets
propagated to the other mount at /cdrom in all the other clone
namespaces.”h]”hŒ‰So when a CD is inserted and mounted at /cdrom that mount gets
propagated to the other mount at /cdrom in all the other clone
namespaces.”…””}”(hj‘  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K²hjc  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h K©hjC  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj@  ubah}”(h]”h ]”h"]”h$]”h&]”j«  Œ
upperalpha”j­  hj®  Œ)”uh1jA  hj<  ubhé)”}”(hŒoB) A process wants its mounts invisible to any other process, but
still be able to see the other system mounts.”h]”hŒoB) A process wants its mounts invisible to any other process, but
still be able to see the other system mounts.”…””}”(hj³  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K¶hj<  ubj<  )”}”(hX	  Solution:

     To begin with, the administrator can mark the entire mount tree
     as shareable::

         mount --make-rshared /

     A new process can clone off a new namespace. And mark some part
     of its namespace as slave::

         mount --make-rslave /myprivatetree

     Hence forth any mounts within the /myprivatetree done by the
     process will not show up in any other namespace. However mounts
     done in the parent namespace under /myprivatetree still shows
     up in the process's namespace.

”h]”(hé)”}”(hŒ	Solution:”h]”hŒ	Solution:”…””}”(hjÅ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K¹hjÁ  ubj<  )”}”(hXÌ  To begin with, the administrator can mark the entire mount tree
as shareable::

    mount --make-rshared /

A new process can clone off a new namespace. And mark some part
of its namespace as slave::

    mount --make-rslave /myprivatetree

Hence forth any mounts within the /myprivatetree done by the
process will not show up in any other namespace. However mounts
done in the parent namespace under /myprivatetree still shows
up in the process's namespace.

”h]”(hé)”}”(hŒNTo begin with, the administrator can mark the entire mount tree
as shareable::”h]”hŒMTo begin with, the administrator can mark the entire mount tree
as shareable:”…””}”(hj×  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K»hjÓ  ubjå  )”}”(hŒmount --make-rshared /”h]”hŒmount --make-rshared /”…””}”hjå  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h K¾hjÓ  ubhé)”}”(hŒ[A new process can clone off a new namespace. And mark some part
of its namespace as slave::”h]”hŒZA new process can clone off a new namespace. And mark some part
of its namespace as slave:”…””}”(hjó  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KÀhjÓ  ubjå  )”}”(hŒ"mount --make-rslave /myprivatetree”h]”hŒ"mount --make-rslave /myprivatetree”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h KÃhjÓ  ubhé)”}”(hŒÙHence forth any mounts within the /myprivatetree done by the
process will not show up in any other namespace. However mounts
done in the parent namespace under /myprivatetree still shows
up in the process's namespace.”h]”hŒÛHence forth any mounts within the /myprivatetree done by the
process will not show up in any other namespace. However mounts
done in the parent namespace under /myprivatetree still shows
up in the processâ€™s namespace.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KÅhjÓ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h K»hjÁ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h K¹hj<  ubhé)”}”(hŒiApart from the above semantics this feature provides the
building blocks to solve the following problems:”h]”hŒiApart from the above semantics this feature provides the
building blocks to solve the following problems:”…””}”(hj)  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KËhj<  ubjB  )”}”(hhh]”(jG  )”}”(hX…  Per-user namespace

    The above semantics allows a way to share mounts across
    namespaces.  But namespaces are associated with processes. If
    namespaces are made first class objects with user API to
    associate/disassociate a namespace with userid, then each user
    could have his/her own namespace and tailor it to his/her
    requirements. This needs to be supported in PAM.
”h]”(hé)”}”(hŒPer-user namespace”h]”hŒPer-user namespace”…””}”(hj>  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KÎhj:  ubj<  )”}”(hXY  The above semantics allows a way to share mounts across
namespaces.  But namespaces are associated with processes. If
namespaces are made first class objects with user API to
associate/disassociate a namespace with userid, then each user
could have his/her own namespace and tailor it to his/her
requirements. This needs to be supported in PAM.
”h]”hé)”}”(hXX  The above semantics allows a way to share mounts across
namespaces.  But namespaces are associated with processes. If
namespaces are made first class objects with user API to
associate/disassociate a namespace with userid, then each user
could have his/her own namespace and tailor it to his/her
requirements. This needs to be supported in PAM.”h]”hXX  The above semantics allows a way to share mounts across
namespaces.  But namespaces are associated with processes. If
namespaces are made first class objects with user API to
associate/disassociate a namespace with userid, then each user
could have his/her own namespace and tailor it to his/her
requirements. This needs to be supported in PAM.”…””}”(hjP  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KÐhjL  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h KÐhj:  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj7  ubjG  )”}”(hX=  Versioned files

    If the entire mount tree is visible at multiple locations, then
    an underlying versioning file system can return different
    versions of the file depending on the path used to access that
    file.

    An example is::

        mount --make-shared /
        mount --rbind / /view/v1
        mount --rbind / /view/v2
        mount --rbind / /view/v3
        mount --rbind / /view/v4

    and if /usr has a versioning filesystem mounted, then that
    mount appears at /view/v1/usr, /view/v2/usr, /view/v3/usr and
    /view/v4/usr too

    A user can request v3 version of the file /usr/fs/namespace.c
    by accessing /view/v3/usr/fs/namespace.c . The underlying
    versioning filesystem can then decipher that v3 version of the
    filesystem is being requested and return the corresponding
    inode.
”h]”(hé)”}”(hŒVersioned files”h]”hŒVersioned files”…””}”(hjn  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h K×hjj  ubj<  )”}”(hXä  If the entire mount tree is visible at multiple locations, then
an underlying versioning file system can return different
versions of the file depending on the path used to access that
file.

An example is::

    mount --make-shared /
    mount --rbind / /view/v1
    mount --rbind / /view/v2
    mount --rbind / /view/v3
    mount --rbind / /view/v4

and if /usr has a versioning filesystem mounted, then that
mount appears at /view/v1/usr, /view/v2/usr, /view/v3/usr and
/view/v4/usr too

A user can request v3 version of the file /usr/fs/namespace.c
by accessing /view/v3/usr/fs/namespace.c . The underlying
versioning filesystem can then decipher that v3 version of the
filesystem is being requested and return the corresponding
inode.
”h]”(hé)”}”(hŒ¾If the entire mount tree is visible at multiple locations, then
an underlying versioning file system can return different
versions of the file depending on the path used to access that
file.”h]”hŒ¾If the entire mount tree is visible at multiple locations, then
an underlying versioning file system can return different
versions of the file depending on the path used to access that
file.”…””}”(hj€  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KÙhj|  ubhé)”}”(hŒAn example is::”h]”hŒAn example is:”…””}”(hjŽ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KÞhj|  ubjå  )”}”(hŒymount --make-shared /
mount --rbind / /view/v1
mount --rbind / /view/v2
mount --rbind / /view/v3
mount --rbind / /view/v4”h]”hŒymount --make-shared /
mount --rbind / /view/v1
mount --rbind / /view/v2
mount --rbind / /view/v3
mount --rbind / /view/v4”…””}”hjœ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Kàhj|  ubhé)”}”(hŒ‰and if /usr has a versioning filesystem mounted, then that
mount appears at /view/v1/usr, /view/v2/usr, /view/v3/usr and
/view/v4/usr too”h]”hŒ‰and if /usr has a versioning filesystem mounted, then that
mount appears at /view/v1/usr, /view/v2/usr, /view/v3/usr and
/view/v4/usr too”…””}”(hjª  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kæhj|  ubhé)”}”(hŒøA user can request v3 version of the file /usr/fs/namespace.c
by accessing /view/v3/usr/fs/namespace.c . The underlying
versioning filesystem can then decipher that v3 version of the
filesystem is being requested and return the corresponding
inode.”h]”hŒøA user can request v3 version of the file /usr/fs/namespace.c
by accessing /view/v3/usr/fs/namespace.c . The underlying
versioning filesystem can then decipher that v3 version of the
filesystem is being requested and return the corresponding
inode.”…””}”(hj¸  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kêhj|  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h KÙhjj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj7  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  j±  j­  hj®  j²  Œstart”Kuh1jA  hj<  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h K¤hj+  hžhubeh}”(h]”Œ	use-cases”ah ]”h"]”Œ4) use cases”ah$]”h&]”uh1h´hh¶hžhhŸh³h K¢ubhµ)”}”(hhh]”(hº)”}”(hŒ5) Detailed semantics”h]”hŒ5) Detailed semantics”…””}”(hjê  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjç  hžhhŸh³h Kñubj<  )”}”(hŒçThe section below explains the detailed semantics of
bind, rbind, move, mount, umount and clone-namespace operations.

Note: the word 'vfsmount' and the noun 'mount' have been used
to mean the same thing, throughout this document.
”h]”(hé)”}”(hŒuThe section below explains the detailed semantics of
bind, rbind, move, mount, umount and clone-namespace operations.”h]”hŒuThe section below explains the detailed semantics of
bind, rbind, move, mount, umount and clone-namespace operations.”…””}”(hjü  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kòhjø  ubhé)”}”(hŒoNote: the word 'vfsmount' and the noun 'mount' have been used
to mean the same thing, throughout this document.”h]”hŒwNote: the word â€˜vfsmountâ€™ and the noun â€˜mountâ€™ have been used
to mean the same thing, throughout this document.”…””}”(hj
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kõhjø  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Kòhjç  hžhubhé)”}”(hŒ5a) Mount states”h]”hŒ5a) Mount states”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Køhjç  hžhubj<  )”}”(hX0  A given mount can be in one of the following states

1) shared
2) slave
3) shared and slave
4) private
5) unbindable

A 'propagation event' is defined as event generated on a vfsmount
that leads to mount or unmount actions in other vfsmounts.

A 'peer group' is defined as a group of vfsmounts that propagate
events to each other.

(1) Shared mounts

        A 'shared mount' is defined as a vfsmount that belongs to a
        'peer group'.

        For example::

                mount --make-shared /mnt
                mount --bind /mnt /tmp

        The mount at /mnt and that at /tmp are both shared and belong
        to the same peer group. Anything mounted or unmounted under
        /mnt or /tmp reflect in all the other mounts of its peer
        group.


(2) Slave mounts

        A 'slave mount' is defined as a vfsmount that receives
        propagation events and does not forward propagation events.

        A slave mount as the name implies has a master mount from which
        mount/unmount events are received. Events do not propagate from
        the slave mount to the master.  Only a shared mount can be made
        a slave by executing the following command::

                mount --make-slave mount

        A shared mount that is made as a slave is no more shared unless
        modified to become shared.

(3) Shared and Slave

        A vfsmount can be both shared as well as slave.  This state
        indicates that the mount is a slave of some vfsmount, and
        has its own peer group too.  This vfsmount receives propagation
        events from its master vfsmount, and also forwards propagation
        events to its 'peer group' and to its slave vfsmounts.

        Strictly speaking, the vfsmount is shared having its own
        peer group, and this peer-group is a slave of some other
        peer group.

        Only a slave vfsmount can be made as 'shared and slave' by
        either executing the following command::

                mount --make-shared mount

        or by moving the slave vfsmount under a shared vfsmount.

(4) Private mount

        A 'private mount' is defined as vfsmount that does not
        receive or forward any propagation events.

(5) Unbindable mount

        A 'unbindable mount' is defined as vfsmount that does not
        receive or forward any propagation events and cannot
        be bind mounted.


State diagram:

The state diagram below explains the state transition of a mount,
in response to various commands::

    -----------------------------------------------------------------------
    |             |make-shared |  make-slave  | make-private |make-unbindab|
    --------------|------------|--------------|--------------|-------------|
    |shared       |shared      |*slave/private|   private    | unbindable  |
    |             |            |              |              |             |
    |-------------|------------|--------------|--------------|-------------|
    |slave        |shared      | **slave      |    private   | unbindable  |
    |             |and slave   |              |              |             |
    |-------------|------------|--------------|--------------|-------------|
    |shared       |shared      | slave        |    private   | unbindable  |
    |and slave    |and slave   |              |              |             |
    |-------------|------------|--------------|--------------|-------------|
    |private      |shared      |  **private   |    private   | unbindable  |
    |-------------|------------|--------------|--------------|-------------|
    |unbindable   |shared      |**unbindable  |    private   | unbindable  |
    ------------------------------------------------------------------------

    * if the shared mount is the only mount in its peer group, making it
    slave, makes it private automatically. Note that there is no master to
    which it can be slaved to.

    ** slaving a non-shared mount has no effect on the mount.

Apart from the commands listed below, the 'move' operation also changes
the state of a mount depending on type of the destination mount. Its
explained in section 5d.
”h]”(hé)”}”(hŒ3A given mount can be in one of the following states”h]”hŒ3A given mount can be in one of the following states”…””}”(hj0  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kúhj,  ubjB  )”}”(hhh]”(jG  )”}”(hŒshared”h]”hé)”}”(hjC  h]”hŒshared”…””}”(hjE  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KühjA  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj>  ubjG  )”}”(hŒslave”h]”hé)”}”(hjZ  h]”hŒslave”…””}”(hj\  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h KýhjX  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj>  ubjG  )”}”(hŒshared and slave”h]”hé)”}”(hjq  h]”hŒshared and slave”…””}”(hjs  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kþhjo  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj>  ubjG  )”}”(hŒprivate”h]”hé)”}”(hjˆ  h]”hŒprivate”…””}”(hjŠ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Kÿhj†  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj>  ubjG  )”}”(hŒunbindable
”h]”hé)”}”(hŒ
unbindable”h]”hŒ
unbindable”…””}”(hj¡  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj>  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  Œarabic”j­  hj®  j²  uh1jA  hj,  ubhé)”}”(hŒ|A 'propagation event' is defined as event generated on a vfsmount
that leads to mount or unmount actions in other vfsmounts.”h]”hŒ€A â€˜propagation eventâ€™ is defined as event generated on a vfsmount
that leads to mount or unmount actions in other vfsmounts.”…””}”(hj¼  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj,  ubhé)”}”(hŒVA 'peer group' is defined as a group of vfsmounts that propagate
events to each other.”h]”hŒZA â€˜peer groupâ€™ is defined as a group of vfsmounts that propagate
events to each other.”…””}”(hjÊ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj,  ubjB  )”}”(hhh]”(jG  )”}”(hX‰  Shared mounts

    A 'shared mount' is defined as a vfsmount that belongs to a
    'peer group'.

    For example::

            mount --make-shared /mnt
            mount --bind /mnt /tmp

    The mount at /mnt and that at /tmp are both shared and belong
    to the same peer group. Anything mounted or unmounted under
    /mnt or /tmp reflect in all the other mounts of its peer
    group.

”h]”(hé)”}”(hŒShared mounts”h]”hŒShared mounts”…””}”(hjß  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MhjÛ  ubj<  )”}”(hXV  A 'shared mount' is defined as a vfsmount that belongs to a
'peer group'.

For example::

        mount --make-shared /mnt
        mount --bind /mnt /tmp

The mount at /mnt and that at /tmp are both shared and belong
to the same peer group. Anything mounted or unmounted under
/mnt or /tmp reflect in all the other mounts of its peer
group.

”h]”(hé)”}”(hŒIA 'shared mount' is defined as a vfsmount that belongs to a
'peer group'.”h]”hŒQA â€˜shared mountâ€™ is defined as a vfsmount that belongs to a
â€˜peer groupâ€™.”…””}”(hjñ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M
hjí  ubhé)”}”(hŒFor example::”h]”hŒFor example:”…””}”(hjÿ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhjí  ubjå  )”}”(hŒ/mount --make-shared /mnt
mount --bind /mnt /tmp”h]”hŒ/mount --make-shared /mnt
mount --bind /mnt /tmp”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mhjí  ubhé)”}”(hŒ¹The mount at /mnt and that at /tmp are both shared and belong
to the same peer group. Anything mounted or unmounted under
/mnt or /tmp reflect in all the other mounts of its peer
group.”h]”hŒ¹The mount at /mnt and that at /tmp are both shared and belong
to the same peer group. Anything mounted or unmounted under
/mnt or /tmp reflect in all the other mounts of its peer
group.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhjí  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M
hjÛ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjØ  ubjG  )”}”(hX  Slave mounts

    A 'slave mount' is defined as a vfsmount that receives
    propagation events and does not forward propagation events.

    A slave mount as the name implies has a master mount from which
    mount/unmount events are received. Events do not propagate from
    the slave mount to the master.  Only a shared mount can be made
    a slave by executing the following command::

            mount --make-slave mount

    A shared mount that is made as a slave is no more shared unless
    modified to become shared.
”h]”(hé)”}”(hŒSlave mounts”h]”hŒSlave mounts”…””}”(hj9  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj5  ubj<  )”}”(hXß  A 'slave mount' is defined as a vfsmount that receives
propagation events and does not forward propagation events.

A slave mount as the name implies has a master mount from which
mount/unmount events are received. Events do not propagate from
the slave mount to the master.  Only a shared mount can be made
a slave by executing the following command::

        mount --make-slave mount

A shared mount that is made as a slave is no more shared unless
modified to become shared.
”h]”(hé)”}”(hŒrA 'slave mount' is defined as a vfsmount that receives
propagation events and does not forward propagation events.”h]”hŒvA â€˜slave mountâ€™ is defined as a vfsmount that receives
propagation events and does not forward propagation events.”…””}”(hjK  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MhjG  ubhé)”}”(hŒìA slave mount as the name implies has a master mount from which
mount/unmount events are received. Events do not propagate from
the slave mount to the master.  Only a shared mount can be made
a slave by executing the following command::”h]”hŒëA slave mount as the name implies has a master mount from which
mount/unmount events are received. Events do not propagate from
the slave mount to the master.  Only a shared mount can be made
a slave by executing the following command:”…””}”(hjY  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MhjG  ubjå  )”}”(hŒmount --make-slave mount”h]”hŒmount --make-slave mount”…””}”hjg  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M"hjG  ubhé)”}”(hŒZA shared mount that is made as a slave is no more shared unless
modified to become shared.”h]”hŒZA shared mount that is made as a slave is no more shared unless
modified to become shared.”…””}”(hju  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M$hjG  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mhj5  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjØ  ubjG  )”}”(hX¯  Shared and Slave

    A vfsmount can be both shared as well as slave.  This state
    indicates that the mount is a slave of some vfsmount, and
    has its own peer group too.  This vfsmount receives propagation
    events from its master vfsmount, and also forwards propagation
    events to its 'peer group' and to its slave vfsmounts.

    Strictly speaking, the vfsmount is shared having its own
    peer group, and this peer-group is a slave of some other
    peer group.

    Only a slave vfsmount can be made as 'shared and slave' by
    either executing the following command::

            mount --make-shared mount

    or by moving the slave vfsmount under a shared vfsmount.
”h]”(hé)”}”(hŒShared and Slave”h]”hŒShared and Slave”…””}”(hj“  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M'hj  ubj<  )”}”(hXm  A vfsmount can be both shared as well as slave.  This state
indicates that the mount is a slave of some vfsmount, and
has its own peer group too.  This vfsmount receives propagation
events from its master vfsmount, and also forwards propagation
events to its 'peer group' and to its slave vfsmounts.

Strictly speaking, the vfsmount is shared having its own
peer group, and this peer-group is a slave of some other
peer group.

Only a slave vfsmount can be made as 'shared and slave' by
either executing the following command::

        mount --make-shared mount

or by moving the slave vfsmount under a shared vfsmount.
”h]”(hé)”}”(hX+  A vfsmount can be both shared as well as slave.  This state
indicates that the mount is a slave of some vfsmount, and
has its own peer group too.  This vfsmount receives propagation
events from its master vfsmount, and also forwards propagation
events to its 'peer group' and to its slave vfsmounts.”h]”hX/  A vfsmount can be both shared as well as slave.  This state
indicates that the mount is a slave of some vfsmount, and
has its own peer group too.  This vfsmount receives propagation
events from its master vfsmount, and also forwards propagation
events to its â€˜peer groupâ€™ and to its slave vfsmounts.”…””}”(hj¥  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M)hj¡  ubhé)”}”(hŒ}Strictly speaking, the vfsmount is shared having its own
peer group, and this peer-group is a slave of some other
peer group.”h]”hŒ}Strictly speaking, the vfsmount is shared having its own
peer group, and this peer-group is a slave of some other
peer group.”…””}”(hj³  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M/hj¡  ubhé)”}”(hŒcOnly a slave vfsmount can be made as 'shared and slave' by
either executing the following command::”h]”hŒfOnly a slave vfsmount can be made as â€˜shared and slaveâ€™ by
either executing the following command:”…””}”(hjÁ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M3hj¡  ubjå  )”}”(hŒmount --make-shared mount”h]”hŒmount --make-shared mount”…””}”hjÏ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M6hj¡  ubhé)”}”(hŒ8or by moving the slave vfsmount under a shared vfsmount.”h]”hŒ8or by moving the slave vfsmount under a shared vfsmount.”…””}”(hjÝ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M8hj¡  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M)hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjØ  ubjG  )”}”(hŒyPrivate mount

    A 'private mount' is defined as vfsmount that does not
    receive or forward any propagation events.
”h]”(hé)”}”(hŒPrivate mount”h]”hŒPrivate mount”…””}”(hjû  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M:hj÷  ubj<  )”}”(hŒbA 'private mount' is defined as vfsmount that does not
receive or forward any propagation events.
”h]”hé)”}”(hŒaA 'private mount' is defined as vfsmount that does not
receive or forward any propagation events.”h]”hŒeA â€˜private mountâ€™ is defined as vfsmount that does not
receive or forward any propagation events.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M<hj	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M<hj÷  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjØ  ubjG  )”}”(hŒŸUnbindable mount

    A 'unbindable mount' is defined as vfsmount that does not
    receive or forward any propagation events and cannot
    be bind mounted.

”h]”(hé)”}”(hŒUnbindable mount”h]”hŒUnbindable mount”…””}”(hj+  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M?hj'  ubj<  )”}”(hŒA 'unbindable mount' is defined as vfsmount that does not
receive or forward any propagation events and cannot
be bind mounted.

”h]”hé)”}”(hŒA 'unbindable mount' is defined as vfsmount that does not
receive or forward any propagation events and cannot
be bind mounted.”h]”hŒƒA â€˜unbindable mountâ€™ is defined as vfsmount that does not
receive or forward any propagation events and cannot
be bind mounted.”…””}”(hj=  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MAhj9  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MAhj'  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjØ  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  j»  j­  Œ(”j®  j²  uh1jA  hj,  ubhé)”}”(hŒState diagram:”h]”hŒState diagram:”…””}”(hj^  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MFhj,  ubhé)”}”(hŒcThe state diagram below explains the state transition of a mount,
in response to various commands::”h]”hŒbThe state diagram below explains the state transition of a mount,
in response to various commands:”…””}”(hjl  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MHhj,  ubjå  )”}”(hXq  -----------------------------------------------------------------------
|             |make-shared |  make-slave  | make-private |make-unbindab|
--------------|------------|--------------|--------------|-------------|
|shared       |shared      |*slave/private|   private    | unbindable  |
|             |            |              |              |             |
|-------------|------------|--------------|--------------|-------------|
|slave        |shared      | **slave      |    private   | unbindable  |
|             |and slave   |              |              |             |
|-------------|------------|--------------|--------------|-------------|
|shared       |shared      | slave        |    private   | unbindable  |
|and slave    |and slave   |              |              |             |
|-------------|------------|--------------|--------------|-------------|
|private      |shared      |  **private   |    private   | unbindable  |
|-------------|------------|--------------|--------------|-------------|
|unbindable   |shared      |**unbindable  |    private   | unbindable  |
------------------------------------------------------------------------

* if the shared mount is the only mount in its peer group, making it
slave, makes it private automatically. Note that there is no master to
which it can be slaved to.

** slaving a non-shared mount has no effect on the mount.”h]”hXq  -----------------------------------------------------------------------
|             |make-shared |  make-slave  | make-private |make-unbindab|
--------------|------------|--------------|--------------|-------------|
|shared       |shared      |*slave/private|   private    | unbindable  |
|             |            |              |              |             |
|-------------|------------|--------------|--------------|-------------|
|slave        |shared      | **slave      |    private   | unbindable  |
|             |and slave   |              |              |             |
|-------------|------------|--------------|--------------|-------------|
|shared       |shared      | slave        |    private   | unbindable  |
|and slave    |and slave   |              |              |             |
|-------------|------------|--------------|--------------|-------------|
|private      |shared      |  **private   |    private   | unbindable  |
|-------------|------------|--------------|--------------|-------------|
|unbindable   |shared      |**unbindable  |    private   | unbindable  |
------------------------------------------------------------------------

* if the shared mount is the only mount in its peer group, making it
slave, makes it private automatically. Note that there is no master to
which it can be slaved to.

** slaving a non-shared mount has no effect on the mount.”…””}”hjz  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MKhj,  ubhé)”}”(hŒ¥Apart from the commands listed below, the 'move' operation also changes
the state of a mount depending on type of the destination mount. Its
explained in section 5d.”h]”hŒ©Apart from the commands listed below, the â€˜moveâ€™ operation also changes
the state of a mount depending on type of the destination mount. Its
explained in section 5d.”…””}”(hjˆ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mbhj,  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Kúhjç  hžhubhé)”}”(hŒ5b) Bind semantics”h]”hŒ5b) Bind semantics”…””}”(hjœ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mfhjç  hžhubj<  )”}”(hX
      Consider the following command::

        mount --bind A/a  B/b

    where 'A' is the source mount, 'a' is the dentry in the mount 'A', 'B'
    is the destination mount and 'b' is the dentry in the destination mount.

    The outcome depends on the type of mount of 'A' and 'B'. The table
    below contains quick reference::

        --------------------------------------------------------------------------
        |         BIND MOUNT OPERATION                                           |
        |************************************************************************|
        |source(A)->| shared      |       private  |       slave    | unbindable |
        | dest(B)  |              |                |                |            |
        |   |      |              |                |                |            |
        |   v      |              |                |                |            |
        |************************************************************************|
        |  shared  | shared       |     shared     | shared & slave |  invalid   |
        |          |              |                |                |            |
        |non-shared| shared       |      private   |      slave     |  invalid   |
        **************************************************************************

    Details:

1. 'A' is a shared mount and 'B' is a shared mount. A new mount 'C'
    which is clone of 'A', is created. Its root dentry is 'a' . 'C' is
    mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
    are created and mounted at the dentry 'b' on all mounts where 'B'
    propagates to. A new propagation tree containing 'C1',..,'Cn' is
    created. This propagation tree is identical to the propagation tree of
    'B'.  And finally the peer-group of 'C' is merged with the peer group
    of 'A'.

2. 'A' is a private mount and 'B' is a shared mount. A new mount 'C'
    which is clone of 'A', is created. Its root dentry is 'a'. 'C' is
    mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
    are created and mounted at the dentry 'b' on all mounts where 'B'
    propagates to. A new propagation tree is set containing all new mounts
    'C', 'C1', .., 'Cn' with exactly the same configuration as the
    propagation tree for 'B'.

3. 'A' is a slave mount of mount 'Z' and 'B' is a shared mount. A new
    mount 'C' which is clone of 'A', is created. Its root dentry is 'a' .
    'C' is mounted on mount 'B' at dentry 'b'. Also new mounts 'C1', 'C2',
    'C3' ... are created and mounted at the dentry 'b' on all mounts where
    'B' propagates to. A new propagation tree containing the new mounts
    'C','C1',..  'Cn' is created. This propagation tree is identical to the
    propagation tree for 'B'. And finally the mount 'C' and its peer group
    is made the slave of mount 'Z'.  In other words, mount 'C' is in the
    state 'slave and shared'.

4. 'A' is a unbindable mount and 'B' is a shared mount. This is a
    invalid operation.

5. 'A' is a private mount and 'B' is a non-shared(private or slave or
    unbindable) mount. A new mount 'C' which is clone of 'A', is created.
    Its root dentry is 'a'. 'C' is mounted on mount 'B' at dentry 'b'.

6. 'A' is a shared mount and 'B' is a non-shared mount. A new mount 'C'
    which is a clone of 'A' is created. Its root dentry is 'a'. 'C' is
    mounted on mount 'B' at dentry 'b'.  'C' is made a member of the
    peer-group of 'A'.

7. 'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount. A
    new mount 'C' which is a clone of 'A' is created. Its root dentry is
    'a'.  'C' is mounted on mount 'B' at dentry 'b'. Also 'C' is set as a
    slave mount of 'Z'. In other words 'A' and 'C' are both slave mounts of
    'Z'.  All mount/unmount events on 'Z' propagates to 'A' and 'C'. But
    mount/unmount on 'A' do not propagate anywhere else. Similarly
    mount/unmount on 'C' do not propagate anywhere else.

8. 'A' is a unbindable mount and 'B' is a non-shared mount. This is a
    invalid operation. A unbindable mount cannot be bind mounted.
”h]”(j<  )”}”(hXñ  Consider the following command::

    mount --bind A/a  B/b

where 'A' is the source mount, 'a' is the dentry in the mount 'A', 'B'
is the destination mount and 'b' is the dentry in the destination mount.

The outcome depends on the type of mount of 'A' and 'B'. The table
below contains quick reference::

    --------------------------------------------------------------------------
    |         BIND MOUNT OPERATION                                           |
    |************************************************************************|
    |source(A)->| shared      |       private  |       slave    | unbindable |
    | dest(B)  |              |                |                |            |
    |   |      |              |                |                |            |
    |   v      |              |                |                |            |
    |************************************************************************|
    |  shared  | shared       |     shared     | shared & slave |  invalid   |
    |          |              |                |                |            |
    |non-shared| shared       |      private   |      slave     |  invalid   |
    **************************************************************************

Details:
”h]”(hé)”}”(hŒ Consider the following command::”h]”hŒConsider the following command:”…””}”(hj²  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhhj®  ubjå  )”}”(hŒmount --bind A/a  B/b”h]”hŒmount --bind A/a  B/b”…””}”hjÀ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mjhj®  ubhé)”}”(hŒwhere 'A' is the source mount, 'a' is the dentry in the mount 'A', 'B'
is the destination mount and 'b' is the dentry in the destination mount.”h]”hŒ£where â€˜Aâ€™ is the source mount, â€˜aâ€™ is the dentry in the mount â€˜Aâ€™, â€˜Bâ€™
is the destination mount and â€˜bâ€™ is the dentry in the destination mount.”…””}”(hjÎ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mlhj®  ubhé)”}”(hŒcThe outcome depends on the type of mount of 'A' and 'B'. The table
below contains quick reference::”h]”hŒjThe outcome depends on the type of mount of â€˜Aâ€™ and â€˜Bâ€™. The table
below contains quick reference:”…””}”(hjÜ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mohj®  ubjå  )”}”(hXƒ  --------------------------------------------------------------------------
|         BIND MOUNT OPERATION                                           |
|************************************************************************|
|source(A)->| shared      |       private  |       slave    | unbindable |
| dest(B)  |              |                |                |            |
|   |      |              |                |                |            |
|   v      |              |                |                |            |
|************************************************************************|
|  shared  | shared       |     shared     | shared & slave |  invalid   |
|          |              |                |                |            |
|non-shared| shared       |      private   |      slave     |  invalid   |
**************************************************************************”h]”hXƒ  --------------------------------------------------------------------------
|         BIND MOUNT OPERATION                                           |
|************************************************************************|
|source(A)->| shared      |       private  |       slave    | unbindable |
| dest(B)  |              |                |                |            |
|   |      |              |                |                |            |
|   v      |              |                |                |            |
|************************************************************************|
|  shared  | shared       |     shared     | shared & slave |  invalid   |
|          |              |                |                |            |
|non-shared| shared       |      private   |      slave     |  invalid   |
**************************************************************************”…””}”hjê  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mrhj®  ubhé)”}”(hŒDetails:”h]”hŒDetails:”…””}”(hjø  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj®  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mhhjª  ubjB  )”}”(hhh]”(jG  )”}”(hXë  'A' is a shared mount and 'B' is a shared mount. A new mount 'C'
 which is clone of 'A', is created. Its root dentry is 'a' . 'C' is
 mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
 are created and mounted at the dentry 'b' on all mounts where 'B'
 propagates to. A new propagation tree containing 'C1',..,'Cn' is
 created. This propagation tree is identical to the propagation tree of
 'B'.  And finally the peer-group of 'C' is merged with the peer group
 of 'A'.
”h]”jk  )”}”(hhh]”jp  )”}”(hXä  'A' is a shared mount and 'B' is a shared mount. A new mount 'C'
which is clone of 'A', is created. Its root dentry is 'a' . 'C' is
mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
are created and mounted at the dentry 'b' on all mounts where 'B'
propagates to. A new propagation tree containing 'C1',..,'Cn' is
created. This propagation tree is identical to the propagation tree of
'B'.  And finally the peer-group of 'C' is merged with the peer group
of 'A'.
”h]”(jv  )”}”(hŒ@'A' is a shared mount and 'B' is a shared mount. A new mount 'C'”h]”hŒLâ€˜Aâ€™ is a shared mount and â€˜Bâ€™ is a shared mount. A new mount â€˜Câ€™”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mˆhj	  ubj†  )”}”(hhh]”hé)”}”(hX¢  which is clone of 'A', is created. Its root dentry is 'a' . 'C' is
mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
are created and mounted at the dentry 'b' on all mounts where 'B'
propagates to. A new propagation tree containing 'C1',..,'Cn' is
created. This propagation tree is identical to the propagation tree of
'B'.  And finally the peer-group of 'C' is merged with the peer group
of 'A'.”h]”hXÞ  which is clone of â€˜Aâ€™, is created. Its root dentry is â€˜aâ€™ . â€˜Câ€™ is
mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™. Also new mount â€˜C1â€™, â€˜C2â€™, â€˜C3â€™ ...
are created and mounted at the dentry â€˜bâ€™ on all mounts where â€˜Bâ€™
propagates to. A new propagation tree containing â€˜C1â€™,..,â€™Cnâ€™ is
created. This propagation tree is identical to the propagation tree of
â€˜Bâ€™.  And finally the peer-group of â€˜Câ€™ is merged with the peer group
of â€˜Aâ€™.”…””}”(hj+	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M‚hj(	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj	  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mˆhj	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubjG  )”}”(hX´  'A' is a private mount and 'B' is a shared mount. A new mount 'C'
 which is clone of 'A', is created. Its root dentry is 'a'. 'C' is
 mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
 are created and mounted at the dentry 'b' on all mounts where 'B'
 propagates to. A new propagation tree is set containing all new mounts
 'C', 'C1', .., 'Cn' with exactly the same configuration as the
 propagation tree for 'B'.
”h]”jk  )”}”(hhh]”jp  )”}”(hX®  'A' is a private mount and 'B' is a shared mount. A new mount 'C'
which is clone of 'A', is created. Its root dentry is 'a'. 'C' is
mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
are created and mounted at the dentry 'b' on all mounts where 'B'
propagates to. A new propagation tree is set containing all new mounts
'C', 'C1', .., 'Cn' with exactly the same configuration as the
propagation tree for 'B'.
”h]”(jv  )”}”(hŒA'A' is a private mount and 'B' is a shared mount. A new mount 'C'”h]”hŒMâ€˜Aâ€™ is a private mount and â€˜Bâ€™ is a shared mount. A new mount â€˜Câ€™”…””}”(hj\	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MhjX	  ubj†  )”}”(hhh]”hé)”}”(hXk  which is clone of 'A', is created. Its root dentry is 'a'. 'C' is
mounted on mount 'B' at dentry 'b'. Also new mount 'C1', 'C2', 'C3' ...
are created and mounted at the dentry 'b' on all mounts where 'B'
propagates to. A new propagation tree is set containing all new mounts
'C', 'C1', .., 'Cn' with exactly the same configuration as the
propagation tree for 'B'.”h]”hX£  which is clone of â€˜Aâ€™, is created. Its root dentry is â€˜aâ€™. â€˜Câ€™ is
mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™. Also new mount â€˜C1â€™, â€˜C2â€™, â€˜C3â€™ ...
are created and mounted at the dentry â€˜bâ€™ on all mounts where â€˜Bâ€™
propagates to. A new propagation tree is set containing all new mounts
â€˜Câ€™, â€˜C1â€™, .., â€˜Cnâ€™ with exactly the same configuration as the
propagation tree for â€˜Bâ€™.”…””}”(hjm	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M‹hjj	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjX	  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MhjU	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjQ	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubjG  )”}”(hXQ  'A' is a slave mount of mount 'Z' and 'B' is a shared mount. A new
 mount 'C' which is clone of 'A', is created. Its root dentry is 'a' .
 'C' is mounted on mount 'B' at dentry 'b'. Also new mounts 'C1', 'C2',
 'C3' ... are created and mounted at the dentry 'b' on all mounts where
 'B' propagates to. A new propagation tree containing the new mounts
 'C','C1',..  'Cn' is created. This propagation tree is identical to the
 propagation tree for 'B'. And finally the mount 'C' and its peer group
 is made the slave of mount 'Z'.  In other words, mount 'C' is in the
 state 'slave and shared'.
”•      h]”jk  )”}”(hhh]”jp  )”}”(hXI  'A' is a slave mount of mount 'Z' and 'B' is a shared mount. A new
mount 'C' which is clone of 'A', is created. Its root dentry is 'a' .
'C' is mounted on mount 'B' at dentry 'b'. Also new mounts 'C1', 'C2',
'C3' ... are created and mounted at the dentry 'b' on all mounts where
'B' propagates to. A new propagation tree containing the new mounts
'C','C1',..  'Cn' is created. This propagation tree is identical to the
propagation tree for 'B'. And finally the mount 'C' and its peer group
is made the slave of mount 'Z'.  In other words, mount 'C' is in the
state 'slave and shared'.
”h]”(jv  )”}”(hŒB'A' is a slave mount of mount 'Z' and 'B' is a shared mount. A new”h]”hŒNâ€˜Aâ€™ is a slave mount of mount â€˜Zâ€™ and â€˜Bâ€™ is a shared mount. A new”…””}”(hjž	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mšhjš	  ubj†  )”}”(hhh]”hé)”}”(hX  mount 'C' which is clone of 'A', is created. Its root dentry is 'a' .
'C' is mounted on mount 'B' at dentry 'b'. Also new mounts 'C1', 'C2',
'C3' ... are created and mounted at the dentry 'b' on all mounts where
'B' propagates to. A new propagation tree containing the new mounts
'C','C1',..  'Cn' is created. This propagation tree is identical to the
propagation tree for 'B'. And finally the mount 'C' and its peer group
is made the slave of mount 'Z'.  In other words, mount 'C' is in the
state 'slave and shared'.”h]”hXQ  mount â€˜Câ€™ which is clone of â€˜Aâ€™, is created. Its root dentry is â€˜aâ€™ .
â€˜Câ€™ is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™. Also new mounts â€˜C1â€™, â€˜C2â€™,
â€˜C3â€™ ... are created and mounted at the dentry â€˜bâ€™ on all mounts where
â€˜Bâ€™ propagates to. A new propagation tree containing the new mounts
â€˜Câ€™,â€™C1â€™,..  â€˜Cnâ€™ is created. This propagation tree is identical to the
propagation tree for â€˜Bâ€™. And finally the mount â€˜Câ€™ and its peer group
is made the slave of mount â€˜Zâ€™.  In other words, mount â€˜Câ€™ is in the
state â€˜slave and sharedâ€™.”…””}”(hj¯	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M“hj¬	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjš	  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mšhj—	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj“	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubjG  )”}”(hŒS'A' is a unbindable mount and 'B' is a shared mount. This is a
 invalid operation.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒR'A' is a unbindable mount and 'B' is a shared mount. This is a
invalid operation.
”h]”(jv  )”}”(hŒ>'A' is a unbindable mount and 'B' is a shared mount. This is a”h]”hŒFâ€˜Aâ€™ is a unbindable mount and â€˜Bâ€™ is a shared mount. This is a”…””}”(hjà	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MhjÜ	  ubj†  )”}”(hhh]”hé)”}”(hŒinvalid operation.”h]”hŒinvalid operation.”…””}”(hjñ	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhjî	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjÜ	  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MhjÙ	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjÕ	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubjG  )”}”(hŒÎ'A' is a private mount and 'B' is a non-shared(private or slave or
 unbindable) mount. A new mount 'C' which is clone of 'A', is created.
 Its root dentry is 'a'. 'C' is mounted on mount 'B' at dentry 'b'.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒÌ'A' is a private mount and 'B' is a non-shared(private or slave or
unbindable) mount. A new mount 'C' which is clone of 'A', is created.
Its root dentry is 'a'. 'C' is mounted on mount 'B' at dentry 'b'.
”h]”(jv  )”}”(hŒB'A' is a private mount and 'B' is a non-shared(private or slave or”h]”hŒJâ€˜Aâ€™ is a private mount and â€˜Bâ€™ is a non-shared(private or slave or”…””}”(hj"
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M¡hj
  ubj†  )”}”(hhh]”hé)”}”(hŒˆunbindable) mount. A new mount 'C' which is clone of 'A', is created.
Its root dentry is 'a'. 'C' is mounted on mount 'B' at dentry 'b'.”h]”hŒ unbindable) mount. A new mount â€˜Câ€™ which is clone of â€˜Aâ€™, is created.
Its root dentry is â€˜aâ€™. â€˜Câ€™ is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.”…””}”(hj3
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M hj0
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M¡hj
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubjG  )”}”(hŒß'A' is a shared mount and 'B' is a non-shared mount. A new mount 'C'
 which is a clone of 'A' is created. Its root dentry is 'a'. 'C' is
 mounted on mount 'B' at dentry 'b'.  'C' is made a member of the
 peer-group of 'A'.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒÜ'A' is a shared mount and 'B' is a non-shared mount. A new mount 'C'
which is a clone of 'A' is created. Its root dentry is 'a'. 'C' is
mounted on mount 'B' at dentry 'b'.  'C' is made a member of the
peer-group of 'A'.
”h]”(jv  )”}”(hŒD'A' is a shared mount and 'B' is a non-shared mount. A new mount 'C'”h]”hŒPâ€˜Aâ€™ is a shared mount and â€˜Bâ€™ is a non-shared mount. A new mount â€˜Câ€™”…””}”(hjd
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M¦hj`
  ubj†  )”}”(hhh]”hé)”}”(hŒ–which is a clone of 'A' is created. Its root dentry is 'a'. 'C' is
mounted on mount 'B' at dentry 'b'.  'C' is made a member of the
peer-group of 'A'.”h]”hŒ²which is a clone of â€˜Aâ€™ is created. Its root dentry is â€˜aâ€™. â€˜Câ€™ is
mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.  â€˜Câ€™ is made a member of the
peer-group of â€˜Aâ€™.”…””}”(hju
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¤hjr
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj`
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M¦hj]
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjY
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubjG  )”}”(hXÕ  'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount. A
 new mount 'C' which is a clone of 'A' is created. Its root dentry is
 'a'.  'C' is mounted on mount 'B' at dentry 'b'. Also 'C' is set as a
 slave mount of 'Z'. In other words 'A' and 'C' are both slave mounts of
 'Z'.  All mount/unmount events on 'Z' propagates to 'A' and 'C'. But
 mount/unmount on 'A' do not propagate anywhere else. Similarly
 mount/unmount on 'C' do not propagate anywhere else.
”h]”jk  )”}”(hhh]”jp  )”}”(hXÏ  'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount. A
new mount 'C' which is a clone of 'A' is created. Its root dentry is
'a'.  'C' is mounted on mount 'B' at dentry 'b'. Also 'C' is set as a
slave mount of 'Z'. In other words 'A' and 'C' are both slave mounts of
'Z'.  All mount/unmount events on 'Z' propagates to 'A' and 'C'. But
mount/unmount on 'A' do not propagate anywhere else. Similarly
mount/unmount on 'C' do not propagate anywhere else.
”h]”(jv  )”}”(hŒB'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount. A”h]”hŒNâ€˜Aâ€™ is a slave mount of mount â€˜Zâ€™ and â€˜Bâ€™ is a non-shared mount. A”…””}”(hj¦
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M®hj¢
  ubj†  )”}”(hhh]”hé)”}”(hX‹  new mount 'C' which is a clone of 'A' is created. Its root dentry is
'a'.  'C' is mounted on mount 'B' at dentry 'b'. Also 'C' is set as a
slave mount of 'Z'. In other words 'A' and 'C' are both slave mounts of
'Z'.  All mount/unmount events on 'Z' propagates to 'A' and 'C'. But
mount/unmount on 'A' do not propagate anywhere else. Similarly
mount/unmount on 'C' do not propagate anywhere else.”h]”hXË  new mount â€˜Câ€™ which is a clone of â€˜Aâ€™ is created. Its root dentry is
â€˜aâ€™.  â€˜Câ€™ is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™. Also â€˜Câ€™ is set as a
slave mount of â€˜Zâ€™. In other words â€˜Aâ€™ and â€˜Câ€™ are both slave mounts of
â€˜Zâ€™.  All mount/unmount events on â€˜Zâ€™ propagates to â€˜Aâ€™ and â€˜Câ€™. But
mount/unmount on â€˜Aâ€™ do not propagate anywhere else. Similarly
mount/unmount on â€˜Câ€™ do not propagate anywhere else.”…””}”(hj·
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M©hj´
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj¢
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M®hjŸ
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj›
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubjG  )”}”(hŒ‚'A' is a unbindable mount and 'B' is a non-shared mount. This is a
 invalid operation. A unbindable mount cannot be bind mounted.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒ'A' is a unbindable mount and 'B' is a non-shared mount. This is a
invalid operation. A unbindable mount cannot be bind mounted.
”h]”(jv  )”}”(hŒB'A' is a unbindable mount and 'B' is a non-shared mount. This is a”h]”hŒJâ€˜Aâ€™ is a unbindable mount and â€˜Bâ€™ is a non-shared mount. This is a”…””}”(hjè
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M±hjä
  ubj†  )”}”(hhh]”hé)”}”(hŒ=invalid operation. A unbindable mount cannot be bind mounted.”h]”hŒ=invalid operation. A unbindable mount cannot be bind mounted.”…””}”(hjù
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M±hjö
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjä
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M±hjá
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjÝ
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj	  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  j»  j­  hj®  j¯  uh1jA  hjª  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mhhjç  hžhubhé)”}”(hŒ5c) Rbind semantics”h]”hŒ5c) Rbind semantics”…””}”(hj+  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M³hjç  hžhubj<  )”}”(hX"  rbind is same as bind. Bind replicates the specified mount.  Rbind
replicates all the mounts in the tree belonging to the specified mount.
Rbind mount is bind mount applied to all the mounts in the tree.

If the source tree that is rbind has some unbindable mounts,
then the subtree under the unbindable mount is pruned in the new
location.

eg:

  let's say we have the following mount tree::

        A
      /   \
      B   C
     / \ / \
     D E F G

  Let's say all the mount except the mount C in the tree are
  of a type other than unbindable.

  If this tree is rbound to say Z

  We will have the following tree at the new location::

        Z
        |
        A'
       /
      B'                Note how the tree under C is pruned
     / \                in the new location.
    D' E'


”h]”(hé)”}”(hŒËrbind is same as bind. Bind replicates the specified mount.  Rbind
replicates all the mounts in the tree belonging to the specified mount.
Rbind mount is bind mount applied to all the mounts in the tree.”h]”hŒËrbind is same as bind. Bind replicates the specified mount.  Rbind
replicates all the mounts in the tree belonging to the specified mount.
Rbind mount is bind mount applied to all the mounts in the tree.”…””}”(hj=  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mµhj9  ubhé)”}”(hŒ‡If the source tree that is rbind has some unbindable mounts,
then the subtree under the unbindable mount is pruned in the new
location.”h]”hŒ‡If the source tree that is rbind has some unbindable mounts,
then the subtree under the unbindable mount is pruned in the new
location.”…””}”(hjK  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¹hj9  ubhé)”}”(hŒeg:”h]”hŒeg:”…””}”(hjY  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M½hj9  ubj<  )”}”(hX¥  let's say we have the following mount tree::

      A
    /   \
    B   C
   / \ / \
   D E F G

Let's say all the mount except the mount C in the tree are
of a type other than unbindable.

If this tree is rbound to say Z

We will have the following tree at the new location::

      Z
      |
      A'
     /
    B'                Note how the tree under C is pruned
   / \                in the new location.
  D' E'


”h]”(hé)”}”(hŒ,let's say we have the following mount tree::”h]”hŒ-letâ€™s say we have the following mount tree:”…””}”(hjk  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¿hjg  ubjå  )”}”(hŒ"   A
 /   \
 B   C
/ \ / \
D E F G”h]”hŒ"   A
 /   \
 B   C
/ \ / \
D E F G”…””}”hjy  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MÁhjg  ubhé)”}”(hŒ[Let's say all the mount except the mount C in the tree are
of a type other than unbindable.”h]”hŒ]Letâ€™s say all the mount except the mount C in the tree are
of a type other than unbindable.”…””}”(hj‡  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÇhjg  ubhé)”}”(hŒIf this tree is rbound to say Z”h]”hŒIf this tree is rbound to say Z”…””}”(hj•  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÊhjg  ubhé)”}”(hŒ5We will have the following tree at the new location::”h]”hŒ4We will have the following tree at the new location:”…””}”(hj£  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÌhjg  ubjå  )”}”(hŒ~    Z
    |
    A'
   /
  B'                Note how the tree under C is pruned
 / \                in the new location.
D' E'”h]”hŒ~    Z
    |
    A'
   /
  B'                Note how the tree under C is pruned
 / \                in the new location.
D' E'”…””}”hj±  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MÎhjg  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M¿hj9  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mµhjç  hžhubhé)”}”(hŒ5d) Move semantics”h]”hŒ5d) Move semantics”…””}”(hjË  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MØhjç  hžhubj<  )”}”(hXf      Consider the following command

    mount --move A  B/b

    where 'A' is the source mount, 'B' is the destination mount and 'b' is
    the dentry in the destination mount.

    The outcome depends on the type of the mount of 'A' and 'B'. The table
    below is a quick reference::

        ---------------------------------------------------------------------------
        |                   MOVE MOUNT OPERATION                                 |
        |**************************************************************************
        | source(A)->| shared      |       private  |       slave    | unbindable |
        | dest(B)  |               |                |                |            |
        |   |      |               |                |                |            |
        |   v      |               |                |                |            |
        |**************************************************************************
        |  shared  | shared        |     shared     |shared and slave|  invalid   |
        |          |               |                |                |            |
        |non-shared| shared        |      private   |    slave       | unbindable |
        ***************************************************************************

    .. Note:: moving a mount residing under a shared mount is invalid.

  Details follow:

1. 'A' is a shared mount and 'B' is a shared mount.  The mount 'A' is
    mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1', 'A2'...'An'
    are created and mounted at dentry 'b' on all mounts that receive
    propagation from mount 'B'. A new propagation tree is created in the
    exact same configuration as that of 'B'. This new propagation tree
    contains all the new mounts 'A1', 'A2'...  'An'.  And this new
    propagation tree is appended to the already existing propagation tree
    of 'A'.

2. 'A' is a private mount and 'B' is a shared mount. The mount 'A' is
    mounted on mount 'B' at dentry 'b'. Also new mount 'A1', 'A2'... 'An'
    are created and mounted at dentry 'b' on all mounts that receive
    propagation from mount 'B'. The mount 'A' becomes a shared mount and a
    propagation tree is created which is identical to that of
    'B'. This new propagation tree contains all the new mounts 'A1',
    'A2'...  'An'.

3. 'A' is a slave mount of mount 'Z' and 'B' is a shared mount.  The
    mount 'A' is mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1',
    'A2'... 'An' are created and mounted at dentry 'b' on all mounts that
    receive propagation from mount 'B'. A new propagation tree is created
    in the exact same configuration as that of 'B'. This new propagation
    tree contains all the new mounts 'A1', 'A2'...  'An'.  And this new
    propagation tree is appended to the already existing propagation tree of
    'A'.  Mount 'A' continues to be the slave mount of 'Z' but it also
    becomes 'shared'.

4. 'A' is a unbindable mount and 'B' is a shared mount. The operation
    is invalid. Because mounting anything on the shared mount 'B' can
    create new mounts that get mounted on the mounts that receive
    propagation from 'B'.  And since the mount 'A' is unbindable, cloning
    it to mount at other mountpoints is not possible.

5. 'A' is a private mount and 'B' is a non-shared(private or slave or
    unbindable) mount. The mount 'A' is mounted on mount 'B' at dentry 'b'.

6. 'A' is a shared mount and 'B' is a non-shared mount.  The mount 'A'
    is mounted on mount 'B' at dentry 'b'.  Mount 'A' continues to be a
    shared mount.

7. 'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount.
    The mount 'A' is mounted on mount 'B' at dentry 'b'.  Mount 'A'
    continues to be a slave mount of mount 'Z'.

8. 'A' is a unbindable mount and 'B' is a non-shared mount. The mount
    'A' is mounted on mount 'B' at dentry 'b'. Mount 'A' continues to be a
    unbindable mount.
”h]”(j<  )”}”(hXA    Consider the following command

  mount --move A  B/b

  where 'A' is the source mount, 'B' is the destination mount and 'b' is
  the dentry in the destination mount.

  The outcome depends on the type of the mount of 'A' and 'B'. The table
  below is a quick reference::

      ---------------------------------------------------------------------------
      |                   MOVE MOUNT OPERATION                                 |
      |**************************************************************************
      | source(A)->| shared      |       private  |       slave    | unbindable |
      | dest(B)  |               |                |                |            |
      |   |      |               |                |                |            |
      |   v      |               |                |                |            |
      |**************************************************************************
      |  shared  | shared        |     shared     |shared and slave|  invalid   |
      |          |               |                |                |            |
      |non-shared| shared        |      private   |    slave       | unbindable |
      ***************************************************************************

  .. Note:: moving a mount residing under a shared mount is invalid.

Details follow:
”h]”(j<  )”}”(hX
  Consider the following command

mount --move A  B/b

where 'A' is the source mount, 'B' is the destination mount and 'b' is
the dentry in the destination mount.

The outcome depends on the type of the mount of 'A' and 'B'. The table
below is a quick reference::

    ---------------------------------------------------------------------------
    |                   MOVE MOUNT OPERATION                                 |
    |**************************************************************************
    | source(A)->| shared      |       private  |       slave    | unbindable |
    | dest(B)  |               |                |                |            |
    |   |      |               |                |                |            |
    |   v      |               |                |                |            |
    |**************************************************************************
    |  shared  | shared        |     shared     |shared and slave|  invalid   |
    |          |               |                |                |            |
    |non-shared| shared        |      private   |    slave       | unbindable |
    ***************************************************************************

.. Note:: moving a mount residing under a shared mount is invalid.
”h]”(hé)”}”(hŒConsider the following command”h]”hŒConsider the following command”…””}”(hjå  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÚhjá  ubhé)”}”(hŒmount --move A  B/b”h]”hŒmount --move A  B/b”…””}”(hjó  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÜhjá  ubhé)”}”(hŒkwhere 'A' is the source mount, 'B' is the destination mount and 'b' is
the dentry in the destination mount.”h]”hŒwwhere â€˜Aâ€™ is the source mount, â€˜Bâ€™ is the destination mount and â€˜bâ€™ is
the dentry in the destination mount.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÞhjá  ubhé)”}”(hŒcThe outcome depends on the type of the mount of 'A' and 'B'. The table
below is a quick reference::”h]”hŒjThe outcome depends on the type of the mount of â€˜Aâ€™ and â€˜Bâ€™. The table
below is a quick reference:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Máhjá  ubjå  )”}”(hXŽ  ---------------------------------------------------------------------------
|                   MOVE MOUNT OPERATION                                 |
|**************************************************************************
| source(A)->| shared      |       private  |       slave    | unbindable |
| dest(B)  |               |                |                |            |
|   |      |               |                |                |            |
|   v      |               |                |                |            |
|**************************************************************************
|  shared  | shared        |     shared     |shared and slave|  invalid   |
|          |               |                |                |            |
|non-shared| shared        |      private   |    slave       | unbindable |
***************************************************************************”h]”hXŽ  ---------------------------------------------------------------------------
|                   MOVE MOUNT OPERATION                                 |
|**************************************************************************
| source(A)->| shared      |       private  |       slave    | unbindable |
| dest(B)  |               |                |                |            |
|   |      |               |                |                |            |
|   v      |               |                |                |            |
|**************************************************************************
|  shared  | shared        |     shared     |shared and slave|  invalid   |
|          |               |                |                |            |
|non-shared| shared        |      private   |    slave       | unbindable |
***************************************************************************”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mähjá  ubhŒnote”“”)”}”(hŒ8moving a mount residing under a shared mount is invalid.”h]”hé)”}”(hj/  h]”hŒ8moving a mount residing under a shared mount is invalid.”…””}”(hj1  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mñhj-  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j+  hjá  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MÚhjÝ  ubhé)”}”(hŒDetails follow:”h]”hŒDetails follow:”…””}”(hjJ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MóhjÝ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MÚhjÙ  ubjB  )”}”(hhh]”(jG  )”}”(hXç  'A' is a shared mount and 'B' is a shared mount.  The mount 'A' is
 mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1', 'A2'...'An'
 are created and mounted at dentry 'b' on all mounts that receive
 propagation from mount 'B'. A new propagation tree is created in the
 exact same configuration as that of 'B'. This new propagation tree
 contains all the new mounts 'A1', 'A2'...  'An'.  And this new
 propagation tree is appended to the already existing propagation tree
 of 'A'.
”h]”jk  )”}”(hhh]”jp  )”}”(hXà  'A' is a shared mount and 'B' is a shared mount.  The mount 'A' is
mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1', 'A2'...'An'
are created and mounted at dentry 'b' on all mounts that receive
propagation from mount 'B'. A new propagation tree is created in the
exact same configuration as that of 'B'. This new propagation tree
contains all the new mounts 'A1', 'A2'...  'An'.  And this new
propagation tree is appended to the already existing propagation tree
of 'A'.
”h]”(jv  )”}”(hŒB'A' is a shared mount and 'B' is a shared mount.  The mount 'A' is”h]”hŒNâ€˜Aâ€™ is a shared mount and â€˜Bâ€™ is a shared mount.  The mount â€˜Aâ€™ is”…””}”(hjl  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mühjh  ubj†  )”}”(hhh]”hé)”}”(hXœ  mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1', 'A2'...'An'
are created and mounted at dentry 'b' on all mounts that receive
propagation from mount 'B'. A new propagation tree is created in the
exact same configuration as that of 'B'. This new propagation tree
contains all the new mounts 'A1', 'A2'...  'An'.  And this new
propagation tree is appended to the already existing propagation tree
of 'A'.”h]”hXÌ  mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.  Also new mounts â€˜A1â€™, â€˜A2â€™...â€™Anâ€™
are created and mounted at dentry â€˜bâ€™ on all mounts that receive
propagation from mount â€˜Bâ€™. A new propagation tree is created in the
exact same configuration as that of â€˜Bâ€™. This new propagation tree
contains all the new mounts â€˜A1â€™, â€˜A2â€™...  â€˜Anâ€™.  And this new
propagation tree is appended to the already existing propagation tree
of â€˜Aâ€™.”…””}”(hj}  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Möhjz  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjh  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mühje  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hja  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubjG  )”}”(hX¡  'A' is a private mount and 'B' is a shared mount. The mount 'A' is
 mounted on mount 'B' at dentry 'b'. Also new mount 'A1', 'A2'... 'An'
 are created and mounted at dentry 'b' on all mounts that receive
 propagation from mount 'B'. The mount 'A' becomes a shared mount and a
 propagation tree is created which is identical to that of
 'B'. This new propagation tree contains all the new mounts 'A1',
 'A2'...  'An'.
”h]”jk  )”}”(hhh]”jp  )”}”(hX›  'A' is a private mount and 'B' is a shared mount. The mount 'A' is
mounted on mount 'B' at dentry 'b'. Also new mount 'A1', 'A2'... 'An'
are created and mounted at dentry 'b' on all mounts that receive
propagation from mount 'B'. The mount 'A' becomes a shared mount and a
propagation tree is created which is identical to that of
'B'. This new propagation tree contains all the new mounts 'A1',
'A2'...  'An'.
”h]”(jv  )”}”(hŒB'A' is a private mount and 'B' is a shared mount. The mount 'A' is”h]”hŒNâ€˜Aâ€™ is a private mount and â€˜Bâ€™ is a shared mount. The mount â€˜Aâ€™ is”…””}”(hj®  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhjª  ubj†  )”}”(hhh]”hé)”}”(hXW  mounted on mount 'B' at dentry 'b'. Also new mount 'A1', 'A2'... 'An'
are created and mounted at dentry 'b' on all mounts that receive
propagation from mount 'B'. The mount 'A' becomes a shared mount and a
propagation tree is created which is identical to that of
'B'. This new propagation tree contains all the new mounts 'A1',
'A2'...  'An'.”h]”hX‡  mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™. Also new mount â€˜A1â€™, â€˜A2â€™... â€˜Anâ€™
are created and mounted at dentry â€˜bâ€™ on all mounts that receive
propagation from mount â€˜Bâ€™. The mount â€˜Aâ€™ becomes a shared mount and a
propagation tree is created which is identical to that of
â€˜Bâ€™. This new propagation tree contains all the new mounts â€˜A1â€™,
â€˜A2â€™...  â€˜Anâ€™.”…””}”(hj¿  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mÿhj¼  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjª  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhj§  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj£  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubjG  )”}”(hXE  'A' is a slave mount of mount 'Z' and 'B' is a shared mount.  The
 mount 'A' is mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1',
 'A2'... 'An' are created and mounted at dentry 'b' on all mounts that
 receive propagation from mount 'B'. A new propagation tree is created
 in the exact same configuration as that of 'B'. This new propagation
 tree contains all the new mounts 'A1', 'A2'...  'An'.  And this new
 propagation tree is appended to the already existing propagation tree of
 'A'.  Mount 'A' continues to be the slave mount of 'Z' but it also
 becomes 'shared'.
”h]”jk  )”}”(hhh]”jp  )”}”(hX=  'A' is a slave mount of mount 'Z' and 'B' is a shared mount.  The
mount 'A' is mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1',
'A2'... 'An' are created and mounted at dentry 'b' on all mounts that
receive propagation from mount 'B'. A new propagation tree is created
in the exact same configuration as that of 'B'. This new propagation
tree contains all the new mounts 'A1', 'A2'...  'An'.  And this new
propagation tree is appended to the already existing propagation tree of
'A'.  Mount 'A' continues to be the slave mount of 'Z' but it also
becomes 'shared'.
”h]”(jv  )”}”(hŒA'A' is a slave mount of mount 'Z' and 'B' is a shared mount.  The”h]”hŒMâ€˜Aâ€™ is a slave mount of mount â€˜Zâ€™ and â€˜Bâ€™ is a shared mount.  The”…””}”(hjð  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhjì  ubj†  )”}”(hhh]”hé)”}”(hXú  mount 'A' is mounted on mount 'B' at dentry 'b'.  Also new mounts 'A1',
'A2'... 'An' are created and mounted at dentry 'b' on all mounts that
receive propagation from mount 'B'. A new propagation tree is created
in the exact same configuration as that of 'B'. This new propagation
tree contains all the new mounts 'A1', 'A2'...  'An'.  And this new
propagation tree is appended to the already existing propagation tree of
'A'.  Mount 'A' continues to be the slave mount of 'Z' but it also
becomes 'shared'.”h]”hX:  mount â€˜Aâ€™ is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.  Also new mounts â€˜A1â€™,
â€˜A2â€™... â€˜Anâ€™ are created and mounted at dentry â€˜bâ€™ on all mounts that
receive propagation from mount â€˜Bâ€™. A new propagation tree is created
in the exact same configuration as that of â€˜Bâ€™. This new propagation
tree contains all the new mounts â€˜A1â€™, â€˜A2â€™...  â€˜Anâ€™.  And this new
propagation tree is appended to the already existing propagation tree of
â€˜Aâ€™.  Mount â€˜Aâ€™ continues to be the slave mount of â€˜Zâ€™ but it also
becomes â€˜sharedâ€™.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhjþ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjì  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhjé  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjå  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubjG  )”}”(hX?  'A' is a unbindable mount and 'B' is a shared mount. The operation
 is invalid. Because mounting anything on the shared mount 'B' can
 create new mounts that get mounted on the mounts that receive
 propagation from 'B'.  And since the mount 'A' is unbindable, cloning
 it to mount at other mountpoints is not possible.
”h]”jk  )”}”(hhh]”jp  )”}”(hX;  'A' is a unbindable mount and 'B' is a shared mount. The operation
is invalid. Because mounting anything on the shared mount 'B' can
create new mounts that get mounted on the mounts that receive
propagation from 'B'.  And since the mount 'A' is unbindable, cloning
it to mount at other mountpoints is not possible.
”h]”(jv  )”}”(hŒB'A' is a unbindable mount and 'B' is a shared mount. The operation”h]”hŒJâ€˜Aâ€™ is a unbindable mount and â€˜Bâ€™ is a shared mount. The operation”…””}”(hj2  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhj.  ubj†  )”}”(hhh]”hé)”}”(hŒ÷is invalid. Because mounting anything on the shared mount 'B' can
create new mounts that get mounted on the mounts that receive
propagation from 'B'.  And since the mount 'A' is unbindable, cloning
it to mount at other mountpoints is not possible.”h]”hX  is invalid. Because mounting anything on the shared mount â€˜Bâ€™ can
create new mounts that get mounted on the mounts that receive
propagation from â€˜Bâ€™.  And since the mount â€˜Aâ€™ is unbindable, cloning
it to mount at other mountpoints is not possible.”…””}”(hjC  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj@  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj.  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhj+  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj'  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubjG  )”}”(hŒŒ'A' is a private mount and 'B' is a non-shared(private or slave or
 unbindable) mount. The mount 'A' is mounted on mount 'B' at dentry 'b'.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒ‹'A' is a private mount and 'B' is a non-shared(private or slave or
unbindable) mount. The mount 'A' is mounted on mount 'B' at dentry 'b'.
”h]”(jv  )”}”(hŒB'A' is a private mount and 'B' is a non-shared(private or slave or”h]”hŒJâ€˜Aâ€™ is a private mount and â€˜Bâ€™ is a non-shared(private or slave or”…””}”(hjt  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhjp  ubj†  )”}”(hhh]”hé)”}”(hŒGunbindable) mount. The mount 'A' is mounted on mount 'B' at dentry 'b'.”h]”hŒSunbindable) mount. The mount â€˜Aâ€™ is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.”…””}”(hj…  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj‚  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjp  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhjm  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hji  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubjG  )”}”(hŒ˜'A' is a shared mount and 'B' is a non-shared mount.  The mount 'A'
 is mounted on mount 'B' at dentry 'b'.  Mount 'A' continues to be a
 shared mount.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒ–'A' is a shared mount and 'B' is a non-shared mount.  The mount 'A'
is mounted on mount 'B' at dentry 'b'.  Mount 'A' continues to be a
shared mount.
”h]”(jv  )”}”(hŒC'A' is a shared mount and 'B' is a non-shared mount.  The mount 'A'”h]”hŒOâ€˜Aâ€™ is a shared mount and â€˜Bâ€™ is a non-shared mount.  The mount â€˜Aâ€™”…””}”(hj¶  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhj²  ubj†  )”}”(hhh]”hé)”}”(hŒQis mounted on mount 'B' at dentry 'b'.  Mount 'A' continues to be a
shared mount.”h]”hŒ]is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.  Mount â€˜Aâ€™ continues to be a
shared mount.”…””}”(hjÇ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MhjÄ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj²  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhj¯  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj«  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubjG  )”}”(hŒ¯'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount.
 The mount 'A' is mounted on mount 'B' at dentry 'b'.  Mount 'A'
 continues to be a slave mount of mount 'Z'.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒ­'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount.
The mount 'A' is mounted on mount 'B' at dentry 'b'.  Mount 'A'
continues to be a slave mount of mount 'Z'.
”h]”(jv  )”}”(hŒ@'A' is a slave mount of mount 'Z' and 'B' is a non-shared mount.”h]”hŒLâ€˜Aâ€™ is a slave mount of mount â€˜Zâ€™ and â€˜Bâ€™ is a non-shared mount.”…””}”(hjø  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhjô  ubj†  )”}”(hhh]”hé)”}”(hŒkThe mount 'A' is mounted on mount 'B' at dentry 'b'.  Mount 'A'
continues to be a slave mount of mount 'Z'.”h]”hŒThe mount â€˜Aâ€™ is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.  Mount â€˜Aâ€™
continues to be a slave mount of mount â€˜Zâ€™.”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjô  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhjñ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjí  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubjG  )”}”(hŒž'A' is a unbindable mount and 'B' is a non-shared mount. The mount
 'A' is mounted on mount 'B' at dentry 'b'. Mount 'A' continues to be a
 unbindable mount.
”h]”jk  )”}”(hhh]”jp  )”}”(hŒœ'A' is a unbindable mount and 'B' is a non-shared mount. The mount
'A' is mounted on mount 'B' at dentry 'b'. Mount 'A' continues to be a
unbindable mount.
”h]”(jv  )”}”(hŒB'A' is a unbindable mount and 'B' is a non-shared mount. The mount”h]”hŒJâ€˜Aâ€™ is a unbindable mount and â€˜Bâ€™ is a non-shared mount. The mount”…””}”(hj:  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M#hj6  ubj†  )”}”(hhh]”hé)”}”(hŒX'A' is mounted on mount 'B' at dentry 'b'. Mount 'A' continues to be a
unbindable mount.”h]”hŒhâ€˜Aâ€™ is mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™. Mount â€˜Aâ€™ continues to be a
unbindable mount.”…””}”(hjK  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M"hjH  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj6  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M#hj3  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj/  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj^  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  j»  j­  hj®  j¯  uh1jA  hjÙ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MÚhjç  hžhubhé)”}”(hŒ5e) Mount semantics”h]”hŒ5e) Mount semantics”…””}”(hj}  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M%hjç  hžhubj<  )”}”(hŒþConsider the following command::

    mount device  B/b

'B' is the destination mount and 'b' is the dentry in the destination
mount.

The above operation is the same as bind operation with the exception
that the source mount is always a private mount.

”h]”(hé)”}”(hŒ Consider the following command::”h]”hŒConsider the following command:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M'hj‹  ubjå  )”}”(hŒmount device  B/b”h]”hŒmount device  B/b”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M)hj‹  ubhé)”}”(hŒL'B' is the destination mount and 'b' is the dentry in the destination
mount.”h]”hŒTâ€˜Bâ€™ is the destination mount and â€˜bâ€™ is the dentry in the destination
mount.”…””}”(hj«  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M+hj‹  ubhé)”}”(hŒuThe above operation is the same as bind operation with the exception
that the source mount is always a private mount.”h]”hŒuThe above operation is the same as bind operation with the exception
that the source mount is always a private mount.”…””}”(hj¹  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M.hj‹  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M'hjç  hžhubhé)”}”(hŒ5f) Unmount semantics”h]”hŒ5f) Unmount semantics”…””}”(hjÍ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M2hjç  hžhubj<  )”}”(hXl  Consider the following command::

    umount A

where 'A' is a mount mounted on mount 'B' at dentry 'b'.

If mount 'B' is shared, then all most-recently-mounted mounts at dentry
'b' on mounts that receive propagation from mount 'B' and does not have
sub-mounts within them are unmounted.

Example: Let's say 'B1', 'B2', 'B3' are shared mounts that propagate to
each other.

let's say 'A1', 'A2', 'A3' are first mounted at dentry 'b' on mount
'B1', 'B2' and 'B3' respectively.

let's say 'C1', 'C2', 'C3' are next mounted at the same dentry 'b' on
mount 'B1', 'B2' and 'B3' respectively.

if 'C1' is unmounted, all the mounts that are most-recently-mounted on
'B1' and on the mounts that 'B1' propagates-to are unmounted.

'B1' propagates to 'B2' and 'B3'. And the most recently mounted mount
on 'B2' at dentry 'b' is 'C2', and that of mount 'B3' is 'C3'.

So all 'C1', 'C2' and 'C3' should be unmounted.

If any of 'C2' or 'C3' has some child mounts, then that mount is not
unmounted, but all other mounts are unmounted. However if 'C1' is told
to be unmounted and 'C1' has some sub-mounts, the umount operation is
failed entirely.
”h]”(hé)”}”(hŒ Consider the following command::”h]”hŒConsider the following command:”…””}”(hjß  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M4hjÛ  ubjå  )”}”(hŒumount A”h]”hŒumount A”…””}”hjí  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M6hjÛ  ubhé)”}”(hŒ8where 'A' is a mount mounted on mount 'B' at dentry 'b'.”h]”hŒDwhere â€˜Aâ€™ is a mount mounted on mount â€˜Bâ€™ at dentry â€˜bâ€™.”…””}”(hjû  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M8hjÛ  ubhé)”}”(hŒµIf mount 'B' is shared, then all most-recently-mounted mounts at dentry
'b' on mounts that receive propagation from mount 'B' and does not have
sub-mounts within them are unmounted.”h]”hŒÁIf mount â€˜Bâ€™ is shared, then all most-recently-mounted mounts at dentry
â€˜bâ€™ on mounts that receive propagation from mount â€˜Bâ€™ and does not have
sub-mounts within them are unmounted.”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M:hjÛ  ubhé)”}”(hŒSExample: Let's say 'B1', 'B2', 'B3' are shared mounts that propagate to
each other.”h]”hŒaExample: Letâ€™s say â€˜B1â€™, â€˜B2â€™, â€˜B3â€™ are shared mounts that propagate to
each other.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M>hjÛ  ubhé)”}”(hŒelet's say 'A1', 'A2', 'A3' are first mounted at dentry 'b' on mount
'B1', 'B2' and 'B3' respectively.”h]”hŒƒletâ€™s say â€˜A1â€™, â€˜A2â€™, â€˜A3â€™ are first mounted at dentry â€˜bâ€™ on mount
â€˜B1â€™, â€˜B2â€™ and â€˜B3â€™ respectively.”…””}”(hj%  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MAhjÛ  ubhé)”}”(hŒmlet's say 'C1', 'C2', 'C3' are next mounted at the same dentry 'b' on
mount 'B1', 'B2' and 'B3' respectively.”h]”hŒ‹letâ€™s say â€˜C1â€™, â€˜C2â€™, â€˜C3â€™ are next mounted at the same dentry â€˜bâ€™ on
mount â€˜B1â€™, â€˜B2â€™ and â€˜B3â€™ respectively.”…””}”(hj3  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MDhjÛ  ubhé)”}”(hŒ„if 'C1' is unmounted, all the mounts that are most-recently-mounted on
'B1' and on the mounts that 'B1' propagates-to are unmounted.”h]”hŒif â€˜C1â€™ is unmounted, all the mounts that are most-recently-mounted on
â€˜B1â€™ and on the mounts that â€˜B1â€™ propagates-to are unmounted.”…””}”(hjA  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MGhjÛ  ubhé)”}”(hŒ„'B1' propagates to 'B2' and 'B3'. And the most recently mounted mount
on 'B2' at dentry 'b' is 'C2', and that of mount 'B3' is 'C3'.”h]”hŒ¤â€˜B1â€™ propagates to â€˜B2â€™ and â€˜B3â€™. And the most recently mounted mount
on â€˜B2â€™ at dentry â€˜bâ€™ is â€˜C2â€™, and that of mount â€˜B3â€™ is â€˜C3â€™.”…””}”(hjO  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MJhjÛ  ubhé)”}”(hŒ/So all 'C1', 'C2' and 'C3' should be unmounted.”h]”hŒ;So all â€˜C1â€™, â€˜C2â€™ and â€˜C3â€™ should be unmounted.”…””}”(hj]  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MMhjÛ  ubhé)”}”(hŒâIf any of 'C2' or 'C3' has some child mounts, then that mount is not
unmounted, but all other mounts are unmounted. However if 'C1' is told
to be unmounted and 'C1' has some sub-mounts, the umount operation is
failed entirely.”h]”hŒòIf any of â€˜C2â€™ or â€˜C3â€™ has some child mounts, then that mount is not
unmounted, but all other mounts are unmounted. However if â€˜C1â€™ is told
to be unmounted and â€˜C1â€™ has some sub-mounts, the umount operation is
failed entirely.”…””}”(hjk  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MOhjÛ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M4hjç  hžhubhé)”}”(hŒ5g) Clone Namespace”h]”hŒ5g) Clone Namespace”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MThjç  hžhubj<  )”}”(hXÄ  A cloned namespace contains all the mounts as that of the parent
namespace.

Let's say 'A' and 'B' are the corresponding mounts in the parent and the
child namespace.

If 'A' is shared, then 'B' is also shared and 'A' and 'B' propagate to
each other.

If 'A' is a slave mount of 'Z', then 'B' is also the slave mount of
'Z'.

If 'A' is a private mount, then 'B' is a private mount too.

If 'A' is unbindable mount, then 'B' is a unbindable mount too.

”h]”(hé)”}”(hŒKA cloned namespace contains all the mounts as that of the parent
namespace.”h]”hŒKA cloned namespace contains all the mounts as that of the parent
namespace.”…””}”(hj‘  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MVhj  ubhé)”}”(hŒYLet's say 'A' and 'B' are the corresponding mounts in the parent and the
child namespace.”h]”hŒcLetâ€™s say â€˜Aâ€™ and â€˜Bâ€™ are the corresponding mounts in the parent and the
child namespace.”…””}”(hjŸ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MYhj  ubhé)”}”(hŒRIf 'A' is shared, then 'B' is also shared and 'A' and 'B' propagate to
each other.”h]”hŒbIf â€˜Aâ€™ is shared, then â€˜Bâ€™ is also shared and â€˜Aâ€™ and â€˜Bâ€™ propagate to
each other.”…””}”(hj­  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M\hj  ubhé)”}”(hŒHIf 'A' is a slave mount of 'Z', then 'B' is also the slave mount of
'Z'.”h]”hŒXIf â€˜Aâ€™ is a slave mount of â€˜Zâ€™, then â€˜Bâ€™ is also the slave mount of
â€˜Zâ€™.”…””}”(hj»  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M_hj  ubhé)”}”(hŒ;If 'A' is a private mount, then 'B' is a private mount too.”h]”hŒCIf â€˜Aâ€™ is a private mount, then â€˜Bâ€™ is a private mount too.”…””}”(hjÉ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mbhj  ubhé)”}”(hŒ?If 'A' is unbindable mount, then 'B' is a unbindable mount too.”h]”hŒGIf â€˜Aâ€™ is unbindable mount, then â€˜Bâ€™ is a unbindable mount too.”…””}”(hj×  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mdhj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MVhjç  hžhubeh}”(h]”Œdetailed-semantics”ah ]”h"]”Œ5) detailed semantics”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kñubhµ)”}”(hhh]”(hº)”}”(hŒ6) Quiz”h]”hŒ6) Quiz”…””}”(hjö  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjó  hžhhŸh³h Mhubj<  )”}”(hXN  A. What is the result of the following command sequence?

        ::

            mount --bind /mnt /mnt
            mount --make-shared /mnt
            mount --bind /mnt /tmp
            mount --move /tmp /mnt/1

        what should be the contents of /mnt /mnt/1 /mnt/1/1 should be?
        Should they all be identical? or should /mnt and /mnt/1 be
        identical only?


B. What is the result of the following command sequence?

        ::

            mount --make-rshared /
            mkdir -p /v/1
            mount --rbind / /v/1

        what should be the content of /v/1/v/1 be?


C. What is the result of the following command sequence?

        ::

            mount --bind /mnt /mnt
            mount --make-shared /mnt
            mkdir -p /mnt/1/2/3 /mnt/1/test
            mount --bind /mnt/1 /tmp
            mount --make-slave /mnt
            mount --make-shared /mnt
            mount --bind /mnt/1/2 /tmp1
            mount --make-slave /mnt

        At this point we have the first mount at /tmp and
        its root dentry is 1. Let's call this mount 'A'
        And then we have a second mount at /tmp1 with root
        dentry 2. Let's call this mount 'B'
        Next we have a third mount at /mnt with root dentry
        mnt. Let's call this mount 'C'

        'B' is the slave of 'A' and 'C' is a slave of 'B'
        A -> B -> C

        at this point if we execute the following command

        mount --bind /bin /tmp/test

        The mount is attempted on 'A'

        will the mount propagate to 'B' and 'C' ?

        what would be the contents of
        /mnt/1/test be?
”h]”jB  )”}”(hhh]”(jG  )”}”(hX_  What is the result of the following command sequence?

     ::

         mount --bind /mnt /mnt
         mount --make-shared /mnt
         mount --bind /mnt /tmp
         mount --move /tmp /mnt/1

     what should be the contents of /mnt /mnt/1 /mnt/1/1 should be?
     Should they all be identical? or should /mnt and /mnt/1 be
     identical only?

”h]”(hé)”}”(hŒ5What is the result of the following command sequence?”h]”hŒ5What is the result of the following command sequence?”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mjhj  ubj<  )”}”(hX   ::

    mount --bind /mnt /mnt
    mount --make-shared /mnt
    mount --bind /mnt /tmp
    mount --move /tmp /mnt/1

what should be the contents of /mnt /mnt/1 /mnt/1/1 should be?
Should they all be identical? or should /mnt and /mnt/1 be
identical only?

”h]”(jå  )”}”(hŒ_mount --bind /mnt /mnt
mount --make-shared /mnt
mount --bind /mnt /tmp
mount --move /tmp /mnt/1”h]”hŒ_mount --bind /mnt /mnt
mount --make-shared /mnt
mount --bind /mnt /tmp
mount --move /tmp /mnt/1”…””}”hj!  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mnhj  ubhé)”}”(hŒ‰what should be the contents of /mnt /mnt/1 /mnt/1/1 should be?
Should they all be identical? or should /mnt and /mnt/1 be
identical only?”h]”hŒ‰what should be the contents of /mnt /mnt/1 /mnt/1/1 should be?
Should they all be identical? or should /mnt and /mnt/1 be
identical only?”…””}”(hj/  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mshj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mlhj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj  ubjG  )”}”(hŒÇWhat is the result of the following command sequence?

     ::

         mount --make-rshared /
         mkdir -p /v/1
         mount --rbind / /v/1

     what should be the content of /v/1/v/1 be?

”h]”(hé)”}”(hŒ5What is the result of the following command sequence?”h]”hŒ5What is the result of the following command sequence?”…””}”(hjM  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MxhjI  ubj<  )”}”(hŒw::

    mount --make-rshared /
    mkdir -p /v/1
    mount --rbind / /v/1

what should be the content of /v/1/v/1 be?

”h]”(jå  )”}”(hŒ9mount --make-rshared /
mkdir -p /v/1
mount --rbind / /v/1”h]”hŒ9mount --make-rshared /
mkdir -p /v/1
mount --rbind / /v/1”…””}”hj_  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M|hj[  ubhé)”}”(hŒ*what should be the content of /v/1/v/1 be?”h]”hŒ*what should be the content of /v/1/v/1 be?”…””}”(hjm  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M€hj[  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MzhjI  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj  ubjG  )”}”(hX±  What is the result of the following command sequence?

     ::

         mount --bind /mnt /mnt
         mount --make-shared /mnt
         mkdir -p /mnt/1/2/3 /mnt/1/test
         mount --bind /mnt/1 /tmp
         mount --make-slave /mnt
         mount --make-shared /mnt
         mount --bind /mnt/1/2 /tmp1
         mount --make-slave /mnt

     At this point we have the first mount at /tmp and
     its root dentry is 1. Let's call this mount 'A'
     And then we have a second mount at /tmp1 with root
     dentry 2. Let's call this mount 'B'
     Next we have a third mount at /mnt with root dentry
     mnt. Let's call this mount 'C'

     'B' is the slave of 'A' and 'C' is a slave of 'B'
     A -> B -> C

     at this point if we execute the following command

     mount --bind /bin /tmp/test

     The mount is attempted on 'A'

     will the mount propagate to 'B' and 'C' ?

     what would be the contents of
     /mnt/1/test be?
”h]”(hé)”}”(hŒ5What is the result of the following command sequence?”h]”hŒ5What is the result of the following command sequence?”…””}”(hj‹  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mƒhj‡  ubj<  )”}”(hX  ::

    mount --bind /mnt /mnt
    mount --make-shared /mnt
    mkdir -p /mnt/1/2/3 /mnt/1/test
    mount --bind /mnt/1 /tmp
    mount --make-slave /mnt
    mount --make-shared /mnt
    mount --bind /mnt/1/2 /tmp1
    mount --make-slave /mnt

At this point we have the first mount at /tmp and
its root dentry is 1. Let's call this mount 'A'
And then we have a second mount at /tmp1 with root
dentry 2. Let's call this mount 'B'
Next we have a third mount at /mnt with root dentry
mnt. Let's call this mount 'C'

'B' is the slave of 'A' and 'C' is a slave of 'B'
A -> B -> C

at this point if we execute the following command

mount --bind /bin /tmp/test

The mount is attempted on 'A'

will the mount propagate to 'B' and 'C' ?

what would be the contents of
/mnt/1/test be?
”h]”(jå  )”}”(hŒÍmount --bind /mnt /mnt
mount --make-shared /mnt
mkdir -p /mnt/1/2/3 /mnt/1/test
mount --bind /mnt/1 /tmp
mount --make-slave /mnt
mount --make-shared /mnt
mount --bind /mnt/1/2 /tmp1
mount --make-slave /mnt”h]”hŒÍmount --bind /mnt /mnt
mount --make-shared /mnt
mkdir -p /mnt/1/2/3 /mnt/1/test
mount --bind /mnt/1 /tmp
mount --make-slave /mnt
mount --make-shared /mnt
mount --bind /mnt/1/2 /tmp1
mount --make-slave /mnt”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M‡hj™  ubhé)”}”(hX  At this point we have the first mount at /tmp and
its root dentry is 1. Let's call this mount 'A'
And then we have a second mount at /tmp1 with root
dentry 2. Let's call this mount 'B'
Next we have a third mount at /mnt with root dentry
mnt. Let's call this mount 'C'”h]”hX  At this point we have the first mount at /tmp and
its root dentry is 1. Letâ€™s call this mount â€˜Aâ€™
And then we have a second mount at /tmp1 with root
dentry 2. Letâ€™s call this mount â€˜Bâ€™
Next we have a third mount at /mnt with root dentry
mnt. Letâ€™s call this mount â€˜Câ€™”…””}”(hj«  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj™  ubhé)”}”(hŒ='B' is the slave of 'A' and 'C' is a slave of 'B'
A -> B -> C”h]”hŒMâ€˜Bâ€™ is the slave of â€˜Aâ€™ and â€˜Câ€™ is a slave of â€˜Bâ€™
A -> B -> C”…””}”(hj¹  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M—hj™  ubhé)”}”(hŒ1at this point if we execute the following command”h]”hŒ1at this point if we execute the following command”…””}”(hjÇ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mšhj™  ubhé)”}”(hŒmount --bind /bin /tmp/test”h]”hŒmount --bind /bin /tmp/test”…””}”(hjÕ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mœhj™  ubhé)”}”(hŒThe mount is attempted on 'A'”h]”hŒ!The mount is attempted on â€˜Aâ€™”…””}”(hjã  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mžhj™  ubhé)”}”(hŒ)will the mount propagate to 'B' and 'C' ?”h]”hŒ1will the mount propagate to â€˜Bâ€™ and â€˜Câ€™ ?”…””}”(hjñ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M hj™  ubhé)”}”(hŒ-what would be the contents of
/mnt/1/test be?”h]”hŒ-what would be the contents of
/mnt/1/test be?”…””}”(hjÿ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¢hj™  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M…hj‡  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  j±  j­  hj®  j¯  uh1jA  hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mjhjó  hžhubeh}”(h]”Œquiz”ah ]”h"]”Œ6) quiz”ah$]”h&]”uh1h´hh¶hžhhŸh³h Mhubhµ)”}”(hhh]”(hº)”}”(hŒ7) FAQ”h]”hŒ7) FAQ”…””}”(hj0  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj-  hžhhŸh³h M¦ubj<  )”}”(hX‘  Q1. Why is bind mount needed? How is it different from symbolic links?
        symbolic links can get stale if the destination mount gets
        unmounted or moved. Bind mounts continue to exist even if the
        other mount is unmounted or moved.

Q2. Why can't the shared subtree be implemented using exportfs?

        exportfs is a heavyweight way of accomplishing part of what
        shared subtree can do. I cannot imagine a way to implement the
        semantics of slave mount using exportfs?

Q3 Why is unbindable mount needed?

        Let's say we want to replicate the mount tree at multiple
        locations within the same subtree.

        if one rbind mounts a tree within the same subtree 'n' times
        the number of mounts created is an exponential function of 'n'.
        Having unbindable mount can help prune the unneeded bind
        mounts. Here is an example.

        step 1:
           let's say the root tree has just two directories with
           one vfsmount::

                            root
                           /    \
                          tmp    usr

            And we want to replicate the tree at multiple
            mountpoints under /root/tmp

        step 2:
              ::


                mount --make-shared /root

                mkdir -p /tmp/m1

                mount --rbind /root /tmp/m1

              the new tree now looks like this::

                            root
                           /    \
                         tmp    usr
                        /
                       m1
                      /  \
                     tmp  usr
                     /
                    m1

                  it has two vfsmounts

        step 3:
            ::

                    mkdir -p /tmp/m2
                    mount --rbind /root /tmp/m2

                the new tree now looks like this::

                              root
                             /    \
                           tmp     usr
                          /    \
                        m1       m2
                       / \       /  \
                     tmp  usr   tmp  usr
                     / \          /
                    m1  m2      m1
                        / \     /  \
                      tmp usr  tmp   usr
                      /        / \
                     m1       m1  m2
                    /  \
                  tmp   usr
                  /  \
                 m1   m2

               it has 6 vfsmounts

        step 4:
              ::
                  mkdir -p /tmp/m3
                  mount --rbind /root /tmp/m3

                  I won't draw the tree..but it has 24 vfsmounts


        at step i the number of vfsmounts is V[i] = i*V[i-1].
        This is an exponential function. And this tree has way more
        mounts than what we really needed in the first place.

        One could use a series of umount at each step to prune
        out the unneeded mounts. But there is a better solution.
        Unclonable mounts come in handy here.

        step 1:
           let's say the root tree has just two directories with
           one vfsmount::

                            root
                           /    \
                          tmp    usr

            How do we set up the same tree at multiple locations under
            /root/tmp

        step 2:
              ::


                mount --bind /root/tmp /root/tmp

                mount --make-rshared /root
                mount --make-unbindable /root/tmp

                mkdir -p /tmp/m1

                mount --rbind /root /tmp/m1

              the new tree now looks like this::

                            root
                           /    \
                         tmp    usr
                        /
                       m1
                      /  \
                     tmp  usr

        step 3:
              ::

                    mkdir -p /tmp/m2
                    mount --rbind /root /tmp/m2

              the new tree now looks like this::

                            root
                           /    \
                         tmp    usr
                        /   \
                       m1     m2
                      /  \     / \
                     tmp  usr tmp usr

        step 4:
              ::

                    mkdir -p /tmp/m3
                    mount --rbind /root /tmp/m3

              the new tree now looks like this::

                                  root
                              /           \
                             tmp           usr
                         /    \    \
                       m1     m2     m3
                      /  \     / \    /  \
                     tmp  usr tmp usr tmp usr
”h]”(jk  )”}”(hhh]”jp  )”}”(hŒãQ1. Why is bind mount needed? How is it different from symbolic links?
symbolic links can get stale if the destination mount gets
unmounted or moved. Bind mounts continue to exist even if the
other mount is unmounted or moved.
”h]”(jv  )”}”(hŒFQ1. Why is bind mount needed? How is it different from symbolic links?”h]”hŒFQ1. Why is bind mount needed? How is it different from symbolic links?”…””}”(hjI  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M«hjE  ubj†  )”}”(hhh]”hé)”}”(hŒ›symbolic links can get stale if the destination mount gets
unmounted or moved. Bind mounts continue to exist even if the
other mount is unmounted or moved.”h]”hŒ›symbolic links can get stale if the destination mount gets
unmounted or moved. Bind mounts continue to exist even if the
other mount is unmounted or moved.”…””}”(hjZ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M©hjW  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjE  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M«hjB  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj>  ubhé)”}”(hŒ?Q2. Why can't the shared subtree be implemented using exportfs?”h]”hŒAQ2. Why canâ€™t the shared subtree be implemented using exportfs?”…””}”(hjz  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M­hj>  ubj<  )”}”(hŒ¤exportfs is a heavyweight way of accomplishing part of what
shared subtree can do. I cannot imagine a way to implement the
semantics of slave mount using exportfs?
”h]”hé)”}”(hŒ£exportfs is a heavyweight way of accomplishing part of what
shared subtree can do. I cannot imagine a way to implement the
semantics of slave mount using exportfs?”h]”hŒ£exportfs is a heavyweight way of accomplishing part of what
shared subtree can do. I cannot imagine a way to implement the
semantics of slave mount using exportfs?”…””}”(hjŒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¯hjˆ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M¯hj>  ubhé)”}”(hŒ"Q3 Why is unbindable mount needed?”h]”hŒ"Q3 Why is unbindable mount needed?”…””}”(hj   hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M³hj>  ubj<  )”}”(hXû  Let's say we want to replicate the mount tree at multiple
locations within the same subtree.

if one rbind mounts a tree within the same subtree 'n' times
the number of mounts created is an exponential function of 'n'.
Having unbindable mount can help prune the unneeded bind
mounts. Here is an example.

step 1:
   let's say the root tree has just two directories with
   one vfsmount::

                    root
                   /    \
                  tmp    usr

    And we want to replicate the tree at multiple
    mountpoints under /root/tmp

step 2:
      ::


        mount --make-shared /root

        mkdir -p /tmp/m1

        mount --rbind /root /tmp/m1

      the new tree now looks like this::

                    root
                   /    \
                 tmp    usr
                /
               m1
              /  \
             tmp  usr
             /
            m1

          it has two vfsmounts

step 3:
    ::

            mkdir -p /tmp/m2
            mount --rbind /root /tmp/m2

        the new tree now looks like this::

                      root
                     /    \
                   tmp     usr
                  /    \
                m1       m2
               / \       /  \
             tmp  usr   tmp  usr
             / \          /
            m1  m2      m1
                / \     /  \
              tmp usr  tmp   usr
              /        / \
             m1       m1  m2
            /  \
          tmp   usr
          /  \
         m1   m2

       it has 6 vfsmounts

step 4:
      ::
          mkdir -p /tmp/m3
          mount --rbind /root /tmp/m3

          I won't draw the tree..but it has 24 vfsmounts


at step i the number of vfsmounts is V[i] = i*V[i-1].
This is an exponential function. And this tree has way more
mounts than what we really needed in the first place.

One could use a series of umount at each step to prune
out the unneeded mounts. But there is a better solution.
Unclonable mounts come in handy here.

step 1:
   let's say the root tree has just two directories with
   one vfsmount::

                    root
                   /    \
                  tmp    usr

    How do we set up the same tree at multiple locations under
    /root/tmp

step 2:
      ::


        mount --bind /root/tmp /root/tmp

        mount --make-rshared /root
        mount --make-unbindable /root/tmp

        mkdir -p /tmp/m1

        mount --rbind /root /tmp/m1

      the new tree now looks like this::

                    root
                   /    \
                 tmp    usr
                /
               m1
              /  \
             tmp  usr

step 3:
      ::

            mkdir -p /tmp/m2
            mount --rbind /root /tmp/m2

      the new tree now looks like this::

                    root
                   /    \
                 tmp    usr
                /   \
               m1     m2
              /  \     / \
             tmp  usr tmp usr

step 4:
      ::

            mkdir -p /tmp/m3
            mount --rbind /root /tmp/m3

      the new tree now looks like this::

                          root
                      /           \
                     tmp           usr
                 /    \    \
               m1     m2     m3
              /  \     / \    /  \
             tmp  usr tmp usr tmp usr
”h]”(hé)”}”(hŒ\Let's say we want to replicate the mount tree at multiple
locations within the same subtree.”h]”hŒ^Letâ€™s say we want to replicate the mount tree at multiple
locations within the same subtree.”…””}”(hj²  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mµhj®  ubhé)”}”(hŒÑif one rbind mounts a tree within the same subtree 'n' times
the number of mounts created is an exponential function of 'n'.
Having unbindable mount can help prune the unneeded bind
mounts. Here is an example.”h]”hŒÙif one rbind mounts a tree within the same subtree â€˜nâ€™ times
the number of mounts created is an exponential function of â€˜nâ€™.
Having unbindable mount can help prune the unneeded bind
mounts. Here is an example.”…””•Žš      }”(hjÀ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¸hj®  ubjk  )”}”(hhh]”(jp  )”}”(hŒâstep 1:
let's say the root tree has just two directories with
one vfsmount::

                 root
                /    \
               tmp    usr

 And we want to replicate the tree at multiple
 mountpoints under /root/tmp
”h]”(jv  )”}”(hŒstep 1:”h]”hŒstep 1:”…””}”(hjÕ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MÆhjÑ  ubj†  )”}”(hhh]”(hé)”}”(hŒDlet's say the root tree has just two directories with
one vfsmount::”h]”hŒEletâ€™s say the root tree has just two directories with
one vfsmount:”…””}”(hjæ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¾hjã  ubjå  )”}”(hŒŽ                root
               /    \
              tmp    usr

And we want to replicate the tree at multiple
mountpoints under /root/tmp”h]”hŒŽ                root
               /    \
              tmp    usr

And we want to replicate the tree at multiple
mountpoints under /root/tmp”…””}”hjô  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MÁhjã  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjÑ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MÆhjÎ  ubjp  )”}”(hX  step 2:
::


  mount --make-shared /root

  mkdir -p /tmp/m1

  mount --rbind /root /tmp/m1

the new tree now looks like this::

              root
             /    \
           tmp    usr
          /
         m1
        /  \
       tmp  usr
       /
      m1

    it has two vfsmounts
”h]”(jv  )”}”(hŒstep 2:”h]”hŒstep 2:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MÞhj  ubj†  )”}”(hhh]”(jå  )”}”(hŒHmount --make-shared /root

mkdir -p /tmp/m1

mount --rbind /root /tmp/m1”h]”hŒHmount --make-shared /root

mkdir -p /tmp/m1

mount --rbind /root /tmp/m1”…””}”hj#  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MÌhj   ubhé)”}”(hŒ"the new tree now looks like this::”h]”hŒ!the new tree now looks like this:”…””}”(hj1  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÒhj   ubjå  )”}”(hŒu          root
         /    \
       tmp    usr
      /
     m1
    /  \
   tmp  usr
   /
  m1

it has two vfsmounts”h]”hŒu          root
         /    \
       tmp    usr
      /
     m1
    /  \
   tmp  usr
   /
  m1

it has two vfsmounts”…””}”hj?  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MÔhj   ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MÞhjÎ  ubjp  )”}”(hX  step 3:
::

        mkdir -p /tmp/m2
        mount --rbind /root /tmp/m2

    the new tree now looks like this::

                  root
                 /    \
               tmp     usr
              /    \
            m1       m2
           / \       /  \
         tmp  usr   tmp  usr
         / \          /
        m1  m2      m1
            / \     /  \
          tmp usr  tmp   usr
          /        / \
         m1       m1  m2
        /  \
      tmp   usr
      /  \
     m1   m2

   it has 6 vfsmounts
”h]”(jv  )”}”(hŒstep 3:”h]”hŒstep 3:”…””}”(hj]  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MúhjY  ubj†  )”}”(hhh]”jå  )”}”(hXµ       mkdir -p /tmp/m2
     mount --rbind /root /tmp/m2

 the new tree now looks like this::

               root
              /    \
            tmp     usr
           /    \
         m1       m2
        / \       /  \
      tmp  usr   tmp  usr
      / \          /
     m1  m2      m1
         / \     /  \
       tmp usr  tmp   usr
       /        / \
      m1       m1  m2
     /  \
   tmp   usr
   /  \
  m1   m2

it has 6 vfsmounts”h]”hXµ       mkdir -p /tmp/m2
     mount --rbind /root /tmp/m2

 the new tree now looks like this::

               root
              /    \
            tmp     usr
           /    \
         m1       m2
        / \       /  \
      tmp  usr   tmp  usr
      / \          /
     m1  m2      m1
         / \     /  \
       tmp usr  tmp   usr
       /        / \
      m1       m1  m2
     /  \
   tmp   usr
   /  \
  m1   m2

it has 6 vfsmounts”…””}”hjn  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mãhjk  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjY  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MúhjÎ  ubjp  )”}”(hŒustep 4:
::
    mkdir -p /tmp/m3
    mount --rbind /root /tmp/m3

    I won't draw the tree..but it has 24 vfsmounts

”h]”(jv  )”}”(hŒstep 4:”h]”hŒstep 4:”…””}”(hjŒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhjˆ  ubj†  )”}”(hhh]”jk  )”}”(hhh]”jp  )”}”(hŒa::
mkdir -p /tmp/m3
mount --rbind /root /tmp/m3

I won't draw the tree..but it has 24 vfsmounts

”h]”(jv  )”}”(hŒ::”h]”hŒ::”…””}”(hj¤  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhj   ubj†  )”}”(hhh]”(hé)”}”(hŒ,mkdir -p /tmp/m3
mount --rbind /root /tmp/m3”h]”hŒ,mkdir -p /tmp/m3
mount --rbind /root /tmp/m3”…””}”(hjµ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mþhj²  ubhé)”}”(hŒ.I won't draw the tree..but it has 24 vfsmounts”h]”hŒ0I wonâ€™t draw the tree..but it has 24 vfsmounts”…””}”(hjÃ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj²  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj   ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjš  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjˆ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MhjÎ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj®  ubhé)”}”(hŒ§at step i the number of vfsmounts is V[i] = i*V[i-1].
This is an exponential function. And this tree has way more
mounts than what we really needed in the first place.”h]”hŒ§at step i the number of vfsmounts is V[i] = i*V[i-1].
This is an exponential function. And this tree has way more
mounts than what we really needed in the first place.”…””}”(hjõ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj®  ubhé)”}”(hŒ•One could use a series of umount at each step to prune
out the unneeded mounts. But there is a better solution.
Unclonable mounts come in handy here.”h]”hŒ•One could use a series of umount at each step to prune
out the unneeded mounts. But there is a better solution.
Unclonable mounts come in handy here.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj®  ubjk  )”}”(hhh]”(jp  )”}”(hŒÝstep 1:
let's say the root tree has just two directories with
one vfsmount::

                 root
                /    \
               tmp    usr

 How do we set up the same tree at multiple locations under
 /root/tmp
”h]”(jv  )”}”(hŒstep 1:”h]”hŒstep 1:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhj  ubj†  )”}”(hhh]”(hé)”}”(hŒDlet's say the root tree has just two directories with
one vfsmount::”h]”hŒEletâ€™s say the root tree has just two directories with
one vfsmount:”…””}”(hj)  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhj&  ubjå  )”}”(hŒ‰                root
               /    \
              tmp    usr

How do we set up the same tree at multiple locations under
/root/tmp”h]”hŒ‰                root
               /    \
              tmp    usr

How do we set up the same tree at multiple locations under
/root/tmp”…””}”hj7  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mhj&  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhj  ubjp  )”}”(hX<  step 2:
::


  mount --bind /root/tmp /root/tmp

  mount --make-rshared /root
  mount --make-unbindable /root/tmp

  mkdir -p /tmp/m1

  mount --rbind /root /tmp/m1

the new tree now looks like this::

              root
             /    \
           tmp    usr
          /
         m1
        /  \
       tmp  usr
”h]”(jv  )”}”(hŒstep 2:”h]”hŒstep 2:”…””}”(hjU  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M,hjQ  ubj†  )”}”(hhh]”(jå  )”}”(hŒmount --bind /root/tmp /root/tmp

mount --make-rshared /root
mount --make-unbindable /root/tmp

mkdir -p /tmp/m1

mount --rbind /root /tmp/m1”h]”hŒmount --bind /root/tmp /root/tmp

mount --make-rshared /root
mount --make-unbindable /root/tmp

mkdir -p /tmp/m1

mount --rbind /root /tmp/m1”…””}”hjf  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h Mhjc  ubhé)”}”(hŒ"the new tree now looks like this::”h]”hŒ!the new tree now looks like this:”…””}”(hjt  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M$hjc  ubjå  )”}”(hŒ@       root
      /    \
    tmp    usr
   /
  m1
 /  \
tmp  usr”h]”hŒ@       root
      /    \
    tmp    usr
   /
  m1
 /  \
tmp  usr”…””}”hj‚  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M&hjc  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjQ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M,hj  ubjp  )”}”(hŒ÷step 3:
::

      mkdir -p /tmp/m2
      mount --rbind /root /tmp/m2

the new tree now looks like this::

              root
             /    \
           tmp    usr
          /   \
         m1     m2
        /  \     / \
       tmp  usr tmp usr
”h]”(jv  )”}”(hŒstep 3:”h]”hŒstep 3:”…””}”(hj   hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M<hjœ  ubj†  )”}”(hhh]”(jå  )”}”(hŒ,mkdir -p /tmp/m2
mount --rbind /root /tmp/m2”h]”hŒ,mkdir -p /tmp/m2
mount --rbind /root /tmp/m2”…””}”hj±  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M1hj®  ubhé)”}”(hŒ"the new tree now looks like this::”h]”hŒ!the new tree now looks like this:”…””}”(hj¿  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M4hj®  ubjå  )”}”(hŒ[       root
      /    \
    tmp    usr
   /   \
  m1     m2
 /  \     / \
tmp  usr tmp usr”h]”hŒ[       root
      /    \
    tmp    usr
   /   \
  m1     m2
 /  \     / \
tmp  usr tmp usr”…””}”hjÍ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M6hj®  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjœ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M<hj  ubjp  )”}”(hX0  step 4:
::

      mkdir -p /tmp/m3
      mount --rbind /root /tmp/m3

the new tree now looks like this::

                    root
                /           \
               tmp           usr
           /    \    \
         m1     m2     m3
        /  \     / \    /  \
       tmp  usr tmp usr tmp usr
”h]”(jv  )”}”(hŒstep 4:”h]”hŒstep 4:”…””}”(hjë  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MLhjç  ubj†  )”}”(hhh]”(jå  )”}”(hŒ,mkdir -p /tmp/m3
mount --rbind /root /tmp/m3”h]”hŒ,mkdir -p /tmp/m3
mount --rbind /root /tmp/m3”…””}”hjü  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MAhjù  ubhé)”}”(hŒ"the new tree now looks like this::”h]”hŒ!the new tree now looks like this:”…””}”(hj
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MDhjù  ubjå  )”}”(hŒ”             root
         /           \
        tmp           usr
    /    \    \
  m1     m2     m3
 /  \     / \    /  \
tmp  usr tmp usr tmp usr”h]”hŒ”             root
         /           \
        tmp           usr
    /    \    \
  m1     m2     m3
 /  \     / \    /  \
tmp  usr tmp usr tmp usr”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h MFhjù  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjç  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MLhj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj®  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mµhj>  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M¨hj-  hžhubeh}”(h]”Œfaq”ah ]”h"]”Œ7) faq”ah$]”h&]”uh1h´hh¶hžhhŸh³h M¦ubhµ)”}”(hhh]”(hº)”}”(hŒ8) Implementation”h]”hŒ8) Implementation”…””}”(hjO  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjL  hžhhŸh³h MOubhé)”}”(hŒ8A) Datastructure”h]”hŒ8A) Datastructure”…””}”(hj]  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MQhjL  hžhubj<  )”}”(hXn  4 new fields are introduced to struct vfsmount:

*   ->mnt_share
*   ->mnt_slave_list
*   ->mnt_slave
*   ->mnt_master

->mnt_share
        links together all the mount to/from which this vfsmount
        send/receives propagation events.

->mnt_slave_list
        links all the mounts to which this vfsmount propagates
        to.

->mnt_slave
        links together all the slaves that its master vfsmount
        propagates to.

->mnt_master
        points to the master vfsmount from which this vfsmount
        receives propagation.

->mnt_flags
        takes two more flags to indicate the propagation status of
        the vfsmount.  MNT_SHARE indicates that the vfsmount is a shared
        vfsmount.  MNT_UNCLONABLE indicates that the vfsmount cannot be
        replicated.

All the shared vfsmounts in a peer group form a cyclic list through
->mnt_share.

All vfsmounts with the same ->mnt_master form on a cyclic list anchored
in ->mnt_master->mnt_slave_list and going through ->mnt_slave.

 ->mnt_master can point to arbitrary (and possibly different) members
 of master peer group.  To find all immediate slaves of a peer group
 you need to go through _all_ ->mnt_slave_list of its members.
 Conceptually it's just a single set - distribution among the
 individual lists does not affect propagation or the way propagation
 tree is modified by operations.

All vfsmounts in a peer group have the same ->mnt_master.  If it is
non-NULL, they form a contiguous (ordered) segment of slave list.

A example propagation tree looks as shown in the figure below.
[ NOTE: Though it looks like a forest, if we consider all the shared
mounts as a conceptual entity called 'pnode', it becomes a tree]::


                A <--> B <--> C <---> D
               /|\            /|      |\
              / F G          J K      H I
             /
            E<-->K
                /|\
               M L N

In the above figure  A,B,C and D all are shared and propagate to each
other.   'A' has got 3 slave mounts 'E' 'F' and 'G' 'C' has got 2 slave
mounts 'J' and 'K'  and  'D' has got two slave mounts 'H' and 'I'.
'E' is also shared with 'K' and they propagate to each other.  And
'K' has 3 slaves 'M', 'L' and 'N'

A's ->mnt_share links with the ->mnt_share of 'B' 'C' and 'D'

A's ->mnt_slave_list links with ->mnt_slave of 'E', 'K', 'F' and 'G'

E's ->mnt_share links with ->mnt_share of K

'E', 'K', 'F', 'G' have their ->mnt_master point to struct vfsmount of 'A'

'M', 'L', 'N' have their ->mnt_master point to struct vfsmount of 'K'

K's ->mnt_slave_list links with ->mnt_slave of 'M', 'L' and 'N'

C's ->mnt_slave_list links with ->mnt_slave of 'J' and 'K'

J and K's ->mnt_master points to struct vfsmount of C

and finally D's ->mnt_slave_list links with ->mnt_slave of 'H' and 'I'

'H' and 'I' have their ->mnt_master pointing to struct vfsmount of 'D'.


NOTE: The propagation tree is orthogonal to the mount tree.
”h]”(hé)”}”(hŒ/4 new fields are introduced to struct vfsmount:”h]”hŒ/4 new fields are introduced to struct vfsmount:”…””}”(hjo  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MShjk  ubhŒbullet_list”“”)”}”(hhh]”(jG  )”}”(hŒ->mnt_share”h]”hé)”}”(hj„  h]”hŒ->mnt_share”…””}”(hj†  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MUhj‚  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj  ubjG  )”}”(hŒ->mnt_slave_list”h]”hé)”}”(hj›  h]”hŒ->mnt_slave_list”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MVhj™  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj  ubjG  )”}”(hŒ->mnt_slave”h]”hé)”}”(hj²  h]”hŒ->mnt_slave”…””}”(hj´  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MWhj°  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj  ubjG  )”}”(hŒ->mnt_master
”h]”hé)”}”(hŒ->mnt_master”h]”hŒ->mnt_master”…””}”(hjË  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MXhjÇ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ*”uh1j}  hŸh³h MUhjk  ubjk  )”}”(hhh]”(jp  )”}”(hŒg->mnt_share
links together all the mount to/from which this vfsmount
send/receives propagation events.
”h]”(jv  )”}”(hŒ->mnt_share”h]”hŒ->mnt_share”…””}”(hjî  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M\hjê  ubj†  )”}”(hhh]”hé)”}”(hŒZlinks together all the mount to/from which this vfsmount
send/receives propagation events.”h]”hŒZlinks together all the mount to/from which this vfsmount
send/receives propagation events.”…””}”(hjÿ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M[hjü  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjê  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M\hjç  ubjp  )”}”(hŒL->mnt_slave_list
links all the mounts to which this vfsmount propagates
to.
”h]”(jv  )”}”(hŒ->mnt_slave_list”h]”hŒ->mnt_slave_list”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h M`hj  ubj†  )”}”(hhh]”hé)”}”(hŒ:links all the mounts to which this vfsmount propagates
to.”h]”hŒ:links all the mounts to which this vfsmount propagates
to.”…””}”(hj.  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M_hj+  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h M`hjç  ubjp  )”}”(hŒR->mnt_slave
links together all the slaves that its master vfsmount
propagates to.
”h]”(jv  )”}”(hŒ->mnt_slave”h]”hŒ->mnt_slave”…””}”(hjL  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MdhjH  ubj†  )”}”(hhh]”hé)”}”(hŒElinks together all the slaves that its master vfsmount
propagates to.”h]”hŒElinks together all the slaves that its master vfsmount
propagates to.”…””}”(hj]  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MchjZ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjH  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mdhjç  ubjp  )”}”(hŒZ->mnt_master
points to the master vfsmount from which this vfsmount
receives propagation.
”h]”(jv  )”}”(hŒ->mnt_master”h]”hŒ->mnt_master”…””}”(hj{  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mhhjw  ubj†  )”}”(hhh]”hé)”}”(hŒLpoints to the master vfsmount from which this vfsmount
receives propagation.”h]”hŒLpoints to the master vfsmount from which this vfsmount
receives propagation.”…””}”(hjŒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mghj‰  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjw  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mhhjç  ubjp  )”}”(hŒÔ->mnt_flags
takes two more flags to indicate the propagation status of
the vfsmount.  MNT_SHARE indicates that the vfsmount is a shared
vfsmount.  MNT_UNCLONABLE indicates that the vfsmount cannot be
replicated.
”h]”(jv  )”}”(hŒ->mnt_flags”h]”hŒ->mnt_flags”…””}”(hjª  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h Mnhj¦  ubj†  )”}”(hhh]”hé)”}”(hŒÇtakes two more flags to indicate the propagation status of
the vfsmount.  MNT_SHARE indicates that the vfsmount is a shared
vfsmount.  MNT_UNCLONABLE indicates that the vfsmount cannot be
replicated.”h]”hŒÇtakes two more flags to indicate the propagation status of
the vfsmount.  MNT_SHARE indicates that the vfsmount is a shared
vfsmount.  MNT_UNCLONABLE indicates that the vfsmount cannot be
replicated.”…””}”(hj»  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mkhj¸  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj¦  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h Mnhjç  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jj  hjk  ubhé)”}”(hŒPAll the shared vfsmounts in a peer group form a cyclic list through
->mnt_share.”h]”hŒPAll the shared vfsmounts in a peer group form a cyclic list through
->mnt_share.”…””}”(hjÛ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mphjk  ubhé)”}”(hŒ†All vfsmounts with the same ->mnt_master form on a cyclic list anchored
in ->mnt_master->mnt_slave_list and going through ->mnt_slave.”h]”hŒ†All vfsmounts with the same ->mnt_master form on a cyclic list anchored
in ->mnt_master->mnt_slave_list and going through ->mnt_slave.”…””}”(hjé  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mshjk  ubj<  )”}”(hXh  ->mnt_master can point to arbitrary (and possibly different) members
of master peer group.  To find all immediate slaves of a peer group
you need to go through _all_ ->mnt_slave_list of its members.
Conceptually it's just a single set - distribution among the
individual lists does not affect propagation or the way propagation
tree is modified by operations.
”h]”hé)”}”(hXg  ->mnt_master can point to arbitrary (and possibly different) members
of master peer group.  To find all immediate slaves of a peer group
you need to go through _all_ ->mnt_slave_list of its members.
Conceptually it's just a single set - distribution among the
individual lists does not affect propagation or the way propagation
tree is modified by operations.”h]”hXi  ->mnt_master can point to arbitrary (and possibly different) members
of master peer group.  To find all immediate slaves of a peer group
you need to go through _all_ ->mnt_slave_list of its members.
Conceptually itâ€™s just a single set - distribution among the
individual lists does not affect propagation or the way propagation
tree is modified by operations.”…””}”(hjû  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mvhj÷  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h Mvhjk  ubhé)”}”(hŒ…All vfsmounts in a peer group have the same ->mnt_master.  If it is
non-NULL, they form a contiguous (ordered) segment of slave list.”h]”hŒ…All vfsmounts in a peer group have the same ->mnt_master.  If it is
non-NULL, they form a contiguous (ordered) segment of slave list.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M}hjk  ubhé)”}”(hŒÆA example propagation tree looks as shown in the figure below.
[ NOTE: Though it looks like a forest, if we consider all the shared
mounts as a conceptual entity called 'pnode', it becomes a tree]::”h]”hŒÉA example propagation tree looks as shown in the figure below.
[ NOTE: Though it looks like a forest, if we consider all the shared
mounts as a conceptual entity called â€˜pnodeâ€™, it becomes a tree]:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M€hjk  ubjå  )”}”(hŒq    A <--> B <--> C <---> D
   /|\            /|      |\
  / F G          J K      H I
 /
E<-->K
    /|\
   M L N”h]”hŒq    A <--> B <--> C <---> D
   /|\            /|      |\
  / F G          J K      H I
 /
E<-->K
    /|\
   M L N”…””}”hj+  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jä  hŸh³h M…hjk  ubhé)”}”(hX5  In the above figure  A,B,C and D all are shared and propagate to each
other.   'A' has got 3 slave mounts 'E' 'F' and 'G' 'C' has got 2 slave
mounts 'J' and 'K'  and  'D' has got two slave mounts 'H' and 'I'.
'E' is also shared with 'K' and they propagate to each other.  And
'K' has 3 slaves 'M', 'L' and 'N'”h]”hXu  In the above figure  A,B,C and D all are shared and propagate to each
other.   â€˜Aâ€™ has got 3 slave mounts â€˜Eâ€™ â€˜Fâ€™ and â€˜Gâ€™ â€˜Câ€™ has got 2 slave
mounts â€˜Jâ€™ and â€˜Kâ€™  and  â€˜Dâ€™ has got two slave mounts â€˜Hâ€™ and â€˜Iâ€™.
â€˜Eâ€™ is also shared with â€˜Kâ€™ and they propagate to each other.  And
â€˜Kâ€™ has 3 slaves â€˜Mâ€™, â€˜Lâ€™ and â€˜Nâ€™”…””}”(hj9  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhjk  ubhé)”}”(hŒ=A's ->mnt_share links with the ->mnt_share of 'B' 'C' and 'D'”h]”hŒKAâ€™s ->mnt_share links with the ->mnt_share of â€˜Bâ€™ â€˜Câ€™ and â€˜Dâ€™”…””}”(hjG  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M“hjk  ubhé)”}”(hŒDA's ->mnt_slave_list links with ->mnt_slave of 'E', 'K', 'F' and 'G'”h]”hŒVAâ€™s ->mnt_slave_list links with ->mnt_slave of â€˜Eâ€™, â€˜Kâ€™, â€˜Fâ€™ and â€˜Gâ€™”…””}”(hjU  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M•hjk  ubhé)”}”(hŒ+E's ->mnt_share links with ->mnt_share of K”h]”hŒ-Eâ€™s ->mnt_share links with ->mnt_share of K”…””}”(hjc  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M—hjk  ubhé)”}”(hŒJ'E', 'K', 'F', 'G' have their ->mnt_master point to struct vfsmount of 'A'”h]”hŒ^â€˜Eâ€™, â€˜Kâ€™, â€˜Fâ€™, â€˜Gâ€™ have their ->mnt_master point to struct vfsmount of â€˜Aâ€™”…””}”(hjq  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M™hjk  ubhé)”}”(hŒE'M', 'L', 'N' have their ->mnt_master point to struct vfsmount of 'K'”h]”hŒUâ€˜Mâ€™, â€˜Lâ€™, â€˜Nâ€™ have their ->mnt_master point to struct vfsmount of â€˜Kâ€™”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M›hjk  ubhé)”}”(hŒ?K's ->mnt_slave_list links with ->mnt_slave of 'M', 'L' and 'N'”h]”hŒMKâ€™s ->mnt_slave_list links with ->mnt_slave of â€˜Mâ€™, â€˜Lâ€™ and â€˜Nâ€™”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mhjk  ubhé)”}”(hŒ:C's ->mnt_slave_list links with ->mnt_slave of 'J' and 'K'”h]”hŒDCâ€™s ->mnt_slave_list links with ->mnt_slave of â€˜Jâ€™ and â€˜Kâ€™”…””}”(hj›  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MŸhjk  ubhé)”}”(hŒ5J and K's ->mnt_master points to struct vfsmount of C”h]”hŒ7J and Kâ€™s ->mnt_master points to struct vfsmount of C”…””}”(hj©  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¡hjk  ubhé)”}”(hŒFand finally D's ->mnt_slave_list links with ->mnt_slave of 'H' and 'I'”h]”hŒPand finally Dâ€™s ->mnt_slave_list links with ->mnt_slave of â€˜Hâ€™ and â€˜Iâ€™”…””}”(hj·  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M£hjk  ubhé)”}”(hŒG'H' and 'I' have their ->mnt_master pointing to struct vfsmount of 'D'.”h]”hŒSâ€˜Hâ€™ and â€˜Iâ€™ have their ->mnt_master pointing to struct vfsmount of â€˜Dâ€™.”…””}”(hjÅ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¥hjk  ubhé)”}”(hŒ;NOTE: The propagation tree is orthogonal to the mount tree.”h]”hŒ;NOTE: The propagation tree is orthogonal to the mount tree.”…””}”(hjÓ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¨hjk  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MShjL  hžhubhé)”}”(hŒ8B Locking:”h]”hŒ8B Locking:”…””}”(hjç  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MªhjL  hžhubj<  )”}”(hXé  ->mnt_share, ->mnt_slave, ->mnt_slave_list, ->mnt_master are protected
by namespace_sem (exclusive for modifications, shared for reading).

Normally we have ->mnt_flags modifications serialized by vfsmount_lock.
There are two exceptions: do_add_mount() and clone_mnt().
The former modifies a vfsmount that has not been visible in any shared
data structures yet.
The latter holds namespace_sem and the only references to vfsmount
are in lists that can't be traversed without namespace_sem.
”h]”(hé)”}”(hŒŠ->mnt_share, ->mnt_slave, ->mnt_slave_list, ->mnt_master are protected
by namespace_sem (exclusive for modifications, shared for reading).”h]”hŒŠ->mnt_share, ->mnt_slave, ->mnt_slave_list, ->mnt_master are protected
by namespace_sem (exclusive for modifications, shared for reading).”…””}”(hjù  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¬hjõ  ubhé)”}”(hX\  Normally we have ->mnt_flags modifications serialized by vfsmount_lock.
There are two exceptions: do_add_mount() and clone_mnt().
The former modifies a vfsmount that has not been visible in any shared
data structures yet.
The latter holds namespace_sem and the only references to vfsmount
are in lists that can't be traversed without namespace_sem.”h]”hX^  Normally we have ->mnt_flags modifications serialized by vfsmount_lock.
There are two exceptions: do_add_mount() and clone_mnt().
The former modifies a vfsmount that has not been visible in any shared
data structures yet.
The latter holds namespace_sem and the only references to vfsmount
are in lists that canâ€™t be traversed without namespace_sem.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¯hjõ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M¬hjL  hžhubhé)”}”(hŒ8C Algorithm:”h]”hŒ8C Algorithm:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¶hjL  hžhubj<  )”}”(hXƒ  The crux of the implementation resides in rbind/move operation.

The overall algorithm breaks the operation into 3 phases: (look at
attach_recursive_mnt() and propagate_mnt())

1. prepare phase.
2. commit phases.
3. abort phases.

Prepare phase:

for each mount in the source tree:

           a) Create the necessary number of mount trees to
                be attached to each of the mounts that receive
                propagation from the destination mount.
           b) Do not attach any of the trees to its destination.
              However note down its ->mnt_parent and ->mnt_mountpoint
           c) Link all the new mounts to form a propagation tree that
              is identical to the propagation tree of the destination
              mount.

           If this phase is successful, there should be 'n' new
           propagation trees; where 'n' is the number of mounts in the
           source tree.  Go to the commit phase

           Also there should be 'm' new mount trees, where 'm' is
           the number of mounts to which the destination mount
           propagates to.

           if any memory allocations fail, go to the abort phase.

Commit phase
        attach each of the mount trees to their corresponding
        destination mounts.

Abort phase
        delete all the newly created trees.

.. Note::
   all the propagation related functionality resides in the file pnode.c

”h]”(hé)”}”(hŒ?The crux of the implementation resides in rbind/move operation.”h]”hŒ?The crux of the implementation resides in rbind/move operation.”…””}”(hj-  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¸hj)  ubhé)”}”(hŒnThe overall algorithm breaks the operation into 3 phases: (look at
attach_recursive_mnt() and propagate_mnt())”h]”hŒnThe overall algorithm breaks the operation into 3 phases: (look at
attach_recursive_mnt() and propagate_mnt())”…””}”(hj;  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h Mºhj)  ubjB  )”}”(hhh]”(jG  )”}”(hŒprepare phase.”h]”hé)”}”(hjN  h]”hŒprepare phase.”…””}”(hjP  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M½hjL  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjI  ubjG  )”}”(hŒcommit phases.”h]”hé)”}”(hje  h]”hŒcommit phases.”…””}”(hjg  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¾hjc  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjI  ubjG  )”}”(hŒabort phases.
”h]”hé)”}”(hŒabort phases.”h]”hŒabort phases.”…””}”(hj~  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h M¿hjz  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hjI  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  j»  j­  hj®  j¯  uh1jA  hj)  ubhé)”}”(hŒPrepare phase:”h]”hŒPrepare phase:”…””}”(hj˜  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÁhj)  ubhé)”}”(hŒ"for each mount in the source tree:”h]”hŒ"for each mount in the source tree:”…””}”(hj¦  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÃhj)  ubj<  )”}”(hXÍ  a) Create the necessary number of mount trees to
     be attached to each of the mounts that receive
     propagation from the destination mount.
b) Do not attach any of the trees to its destination.
   However note down its ->mnt_parent and ->mnt_mountpoint
c) Link all the new mounts to form a propagation tree that
   is identical to the propagation tree of the destination
   mount.

If this phase is successful, there should be 'n' new
propagation trees; where 'n' is the number of mounts in the
source tree.  Go to the commit phase

Also there should be 'm' new mount trees, where 'm' is
the number of mounts to which the destination mount
propagates to.

if any memory allocations fail, go to the abort phase.
”h]”(jB  )”}”(hhh]”(jG  )”}”(hŒˆCreate the necessary number of mount trees to
  be attached to each of the mounts that receive
  propagation from the destination mount.”h]”jk  )”}”(hhh]”jp  )”}”(hŒ„Create the necessary number of mount trees to
be attached to each of the mounts that receive
propagation from the destination mount.”h]”(jv  )”}”(hŒ-Create the necessary number of mount trees to”h]”hŒ-Create the necessary number of mount trees to”…””}”(hjÆ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MÆhjÂ  ubj†  )”}”(hhh]”hé)”}”(hŒVbe attached to each of the mounts that receive
propagation from the destination mount.”h]”hŒVbe attached to each of the mounts that receive
propagation from the destination mount.”…””}”(hj×  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÆhjÔ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjÂ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MÆhj¿  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj»  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj¸  ubjG  )”}”(hŒjDo not attach any of the trees to its destination.
However note down its ->mnt_parent and ->mnt_mountpoint”h]”hé)”}”(hŒjDo not attach any of the trees to its destination.
However note down its ->mnt_parent and ->mnt_mountpoint”h]”hŒjDo not attach any of the trees to its destination.
However note down its ->mnt_parent and ->mnt_mountpoint”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÈhjý  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj¸  ubjG  )”}”(hŒwLink all the new mounts to form a propagation tree that
is identical to the propagation tree of the destination
mount.
”h]”hé)”}”(hŒvLink all the new mounts to form a propagation tree that
is identical to the propagation tree of the destination
mount.”h]”hŒvLink all the new mounts to form a propagation tree that
is identical to the propagation tree of the destination
mount.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÊhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jF  hj¸  ubeh}”(h]”h ]”h"]”h$]”h&]”j«  j¬  j­  hj®  j²  uh1jA  hj´  ubhé)”}”(hŒ•If this phase is successful, there should be 'n' new
propagation trees; where 'n' is the number of mounts in the
source tree.  Go to the commit phase”h]”hŒIf this phase is successful, there should be â€˜nâ€™ new
propagation trees; where â€˜nâ€™ is the number of mounts in the
source tree.  Go to the commit phase”…””}”(hj3  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÎhj´  ubhé)”}”(hŒyAlso there should be 'm' new mount trees, where 'm' is
the number of mounts to which the destination mount
propagates to.”h]”hŒAlso there should be â€˜mâ€™ new mount trees, where â€˜mâ€™ is
the number of mounts to which the destination mount
propagates to.”…””}”(hjA  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÒhj´  ubhé)”}”(hŒ6if any memory allocations fail, go to the abort phase.”h]”hŒ6if any memory allocations fail, go to the abort phase.”…””}”(hjO  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÖhj´  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h MÅhj)  ubjk  )”}”(hhh]”(jp  )”}”(hŒWCommit phase
attach each of the mount trees to their corresponding
destination mounts.
”h]”(jv  )”}”(hŒCommit phase”h]”hŒCommit phase”…””}”(hjj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MÚhjf  ubj†  )”}”(hhh]”hé)”}”(hŒIattach each of the mount trees to their corresponding
destination mounts.”h]”hŒIattach each of the mount trees to their corresponding
destination mounts.”…””}”(hj{  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÙhjx  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hjf  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MÚhjc  ubjp  )”}”(hŒ0Abort phase
delete all the newly created trees.
”h]”(jv  )”}”(hŒAbort phase”h]”hŒAbort phase”…””}”(hj™  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1ju  hŸh³h MÝhj•  ubj†  )”}”(hhh]”hé)”}”(hŒ#delete all the newly created trees.”h]”hŒ#delete all the newly created trees.”…””}”(hjª  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MÝhj§  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j…  hj•  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jo  hŸh³h MÝhjc  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jj  hj)  ubj,  )”}”(hŒEall the propagation related functionality resides in the file pnode.c”h]”hé)”}”(hjÌ  h]”hŒEall the propagation related functionality resides in the file pnode.c”…””}”(hjÎ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MàhjÊ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j+  hj)  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;  hŸh³h M¸hjL  hžhubhŒ
transition”“”)”}”(hŒH------------------------------------------------------------------------”h]”h}”(h]”h ]”h"]”h$]”h&]”uh1jç  hŸh³h MãhjL  hžhubhé)”}”(hŒHversion 0.1  (created the initial document, Ram Pai linuxram@us.ibm.com)”h]”(hŒ4version 0.1  (created the initial document, Ram Pai ”…””}”(hjó  hžhhŸNh NubhŒ	reference”“”)”}”(hŒlinuxram@us.ibm.com”h]”hŒlinuxram@us.ibm.com”…””}”(hjý  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œmailto:linuxram@us.ibm.com”uh1jû  hjó  ubhŒ)”…””}”(hjó  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MåhjL  hžhubhé)”}”(hŒ1version 0.2  (Incorporated comments from Al Viro)”h]”hŒ1version 0.2  (Incorporated comments from Al Viro)”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhŸh³h MçhjL  hžhubeh}”(h]”Œimplementation”ah ]”h"]”Œ8) implementation”ah$]”h&]”uh1h´hh¶hžhhŸh³h MOubeh}”(h]”Œshared-subtrees”ah ]”h"]”Œshared subtrees”ah$]”h&]”uh1h´hhhžhhŸh³h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h³uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¹NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jX  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h³Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(j2  j/  j  j  jé  jæ  j(  j%  jä  já  jð  jí  j*  j'  jI  jF  j*  j'  uŒ	nametypes”}”(j2  ‰j  ‰jé  ‰j(  ‰jä  ‰jð  ‰j*  ‰jI  ‰j*  ‰uh}”(j/  h¶j  h×jæ  j  j%  jì  já  j+  jí  jç  j'  jó  jF  j-  j'  jL  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”(hŒsystem_message”“”)”}”(hhh]”hé)”}”(hŒ:Enumerated list start value not ordinal-1: "C" (ordinal 3)”h]”hŒ>Enumerated list start value not ordinal-1: â€œCâ€ (ordinal 3)”…””}”(hj¿  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhj¼  ubah}”(h]”h ]”h"]”h$]”h&]”Œlevel”KŒtype”ŒINFO”Œsource”h³Œline”Kuh1jº  hj<  ubj»  )”}”(hhh]”hé)”}”(hŒ`Blank line missing before literal block (after the "::")? Interpreted as a definition list item.”h]”hŒdBlank line missing before literal block (after the â€œ::â€)? Interpreted as a definition list item.”…””}”(hjÛ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hèhjØ  ubah}”(h]”h ]”h"]”h$]”h&]”Œlevel”KŒtype”jÕ  Œline”MŒsource”h³uh1jº  hj²  ubeŒtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.