€•“     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/nfs/exporting”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$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/zh_TW/filesystems/nfs/exporting”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/it_IT/filesystems/nfs/exporting”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/ja_JP/filesystems/nfs/exporting”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/ko_KR/filesystems/nfs/exporting”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒPortuguese (Brazilian)”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/pt_BR/filesystems/nfs/exporting”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh–sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ-/translations/sp_SP/filesystems/nfs/exporting”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒMaking Filesystems Exportable”h]”hŒMaking Filesystems Exportable”…””}”(hh¼h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhh·h²hh³ŒG/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting.rst”h´Kubh¶)”}”(hhh]”(h»)”}”(hŒOverview”h]”hŒOverview”…””}”(hhÎh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhhËh²hh³hÊh´KubhŒ	paragraph”“”)”}”(hXU  All filesystem operations require a dentry (or two) as a starting
point.  Local applications have a reference-counted hold on suitable
dentries via open file descriptors or cwd/root.  However remote
applications that access a filesystem via a remote filesystem protocol
such as NFS may not be able to hold such a reference, and so need a
different way to refer to a particular dentry.  As the alternative
form of reference needs to be stable across renames, truncates, and
server-reboot (among other things, though these tend to be the most
problematic), there is no simple answer like 'filename'.”h]”hXY  All filesystem operations require a dentry (or two) as a starting
point.  Local applications have a reference-counted hold on suitable
dentries via open file descriptors or cwd/root.  However remote
applications that access a filesystem via a remote filesystem protocol
such as NFS may not be able to hold such a reference, and so need a
different way to refer to a particular dentry.  As the alternative
form of reference needs to be stable across renames, truncates, and
server-reboot (among other things, though these tend to be the most
problematic), there is no simple answer like â€˜filenameâ€™.”…””}”(hhÞh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K	hhËh²hubhÝ)”}”(hXO  The mechanism discussed here allows each filesystem implementation to
specify how to generate an opaque (outside of the filesystem) byte
string for any dentry, and how to find an appropriate dentry for any
given opaque byte string.
This byte string will be called a "filehandle fragment" as it
corresponds to part of an NFS filehandle.”h]”hXS  The mechanism discussed here allows each filesystem implementation to
specify how to generate an opaque (outside of the filesystem) byte
string for any dentry, and how to find an appropriate dentry for any
given opaque byte string.
This byte string will be called a â€œfilehandle fragmentâ€ as it
corresponds to part of an NFS filehandle.”…””}”(hhìh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KhhËh²hubhÝ)”}”(hŒnA filesystem which supports the mapping between filehandle fragments
and dentries will be termed "exportable".”h]”hŒrA filesystem which supports the mapping between filehandle fragments
and dentries will be termed â€œexportableâ€.”…””}”(hhúh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KhhËh²hubeh}”(h]”Œoverview”ah ]”h"]”Œoverview”ah$]”h&]”uh1hµhh·h²hh³hÊh´Kubh¶)”}”(hhh]”(h»)”}”(hŒDcache Issues”h]”hŒDcache Issues”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj  h²hh³hÊh´K ubhÝ)”}”(hXg  The dcache normally contains a proper prefix of any given filesystem
tree.  This means that if any filesystem object is in the dcache, then
all of the ancestors of that filesystem object are also in the dcache.
As normal access is by filename this prefix is created naturally and
maintained easily (by each object maintaining a reference count on
its parent).”h]”hXg  The dcache normally contains a proper prefix of any given filesystem
tree.  This means that if any filesystem object is in the dcache, then
all of the ancestors of that filesystem object are also in the dcache.
As normal access is by filename this prefix is created naturally and
maintained easily (by each object maintaining a reference count on
its parent).”…””}”(hj!  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K"hj  h²hubhÝ)”}”(hX	  However when objects are included into the dcache by interpreting a
filehandle fragment, there is no automatic creation of a path prefix
for the object.  This leads to two related but distinct features of
the dcache that are not needed for normal filesystem access.”h]”hX	  However when objects are included into the dcache by interpreting a
filehandle fragment, there is no automatic creation of a path prefix
for the object.  This leads to two related but distinct features of
the dcache that are not needed for normal filesystem access.”…””}”(hj/  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K)hj  h²hubhŒenumerated_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒyThe dcache must sometimes contain objects that are not part of the
proper prefix. i.e that are not connected to the root.”h]”hÝ)”}”(hŒyThe dcache must sometimes contain objects that are not part of the
proper prefix. i.e that are not connected to the root.”h]”hŒyThe dcache must sometimes contain objects that are not part of the
proper prefix. i.e that are not connected to the root.”…””}”(hjH  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K.hjD  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj?  h²hh³hÊh´NubjC  )”}”(hXB  The dcache must be prepared for a newly found (via ->lookup) directory
to already have a (non-connected) dentry, and must be able to move
that dentry into place (based on the parent and name in the
->lookup).   This is particularly needed for directories as
it is a dcache invariant that directories only have one dentry.
”h]”hÝ)”}”(hXA  The dcache must be prepared for a newly found (via ->lookup) directory
to already have a (non-connected) dentry, and must be able to move
that dentry into place (based on the parent and name in the
->lookup).   This is particularly needed for directories as
it is a dcache invariant that directories only have one dentry.”h]”hXA  The dcache must be prepared for a newly found (via ->lookup) directory
to already have a (non-connected) dentry, and must be able to move
that dentry into place (based on the parent and name in the
->lookup).   This is particularly needed for directories as
it is a dcache invariant that directories only have one dentry.”…””}”(hj`  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K0hj\  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj?  h²hh³hÊh´Nubeh}”(h]”h ]”h"]”h$]”h&]”Œenumtype”Œarabic”Œprefix”hŒsuffix”Œ.”uh1j=  hj  h²hh³hÊh´K.ubhÝ)”}”(hŒ,To implement these features, the dcache has:”h]”hŒ,To implement these features, the dcache has:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K6hj  h²hubj>  )”}”(hhh]”(jC  )”}”(hXæ  A dentry flag DCACHE_DISCONNECTED which is set on
any dentry that might not be part of the proper prefix.
This is set when anonymous dentries are created, and cleared when a
dentry is noticed to be a child of a dentry which is in the proper
prefix.  If the refcount on a dentry with this flag set
becomes zero, the dentry is immediately discarded, rather than being
kept in the dcache.  If a dentry that is not already in the dcache
is repeatedly accessed by filehandle (as NFSD might do), an new dentry
will be a allocated for each access, and discarded at the end of
the access.

Note that such a dentry can acquire children, name, ancestors, etc.
without losing DCACHE_DISCONNECTED - that flag is only cleared when
subtree is successfully reconnected to root.  Until then dentries
in such subtree are retained only as long as there are references;
refcount reaching zero means immediate eviction, same as for unhashed
dentries.  That guarantees that we won't need to hunt them down upon
umount.
”h]”(hÝ)”}”(hXD  A dentry flag DCACHE_DISCONNECTED which is set on
any dentry that might not be part of the proper prefix.
This is set when anonymous dentries are created, and cleared when a
dentry is noticed to be a child of a dentry which is in the proper
prefix.  If the refcount on a dentry with this flag set
becomes zero, the dentry is immediately discarded, rather than being
kept in the dcache.  If a dentry that is not already in the dcache
is repeatedly accessed by filehandle (as NFSD might do), an new dentry
will be a allocated for each access, and discarded at the end of
the access.”h]”hXD  A dentry flag DCACHE_DISCONNECTED which is set on
any dentry that might not be part of the proper prefix.
This is set when anonymous dentries are created, and cleared when a
dentry is noticed to be a child of a dentry which is in the proper
prefix.  If the refcount on a dentry with this flag set
becomes zero, the dentry is immediately discarded, rather than being
kept in the dcache.  If a dentry that is not already in the dcache
is repeatedly accessed by filehandle (as NFSD might do), an new dentry
will be a allocated for each access, and discarded at the end of
the access.”…””}”(hj”  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K8hj  ubhÝ)”}”(hXŸ  Note that such a dentry can acquire children, name, ancestors, etc.
without losing DCACHE_DISCONNECTED - that flag is only cleared when
subtree is successfully reconnected to root.  Until then dentries
in such subtree are retained only as long as there are references;
refcount reaching zero means immediate eviction, same as for unhashed
dentries.  That guarantees that we won't need to hunt them down upon
umount.”h]”hX¡  Note that such a dentry can acquire children, name, ancestors, etc.
without losing DCACHE_DISCONNECTED - that flag is only cleared when
subtree is successfully reconnected to root.  Until then dentries
in such subtree are retained only as long as there are references;
refcount reaching zero means immediate eviction, same as for unhashed
dentries.  That guarantees that we wonâ€™t need to hunt them down upon
umount.”…””}”(hj¢  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KChj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj  h²hh³hÊh´NubjC  )”}”(hŒãA primitive for creation of secondary roots - d_obtain_root(inode).
Those do _not_ bear DCACHE_DISCONNECTED.  They are placed on the
per-superblock list (->s_roots), so they can be located at umount
time for eviction purposes.
”h]”hÝ)”}”(hŒâA primitive for creation of secondary roots - d_obtain_root(inode).
Those do _not_ bear DCACHE_DISCONNECTED.  They are placed on the
per-superblock list (->s_roots), so they can be located at umount
time for eviction purposes.”h]”hŒâA primitive for creation of secondary roots - d_obtain_root(inode).
Those do _not_ bear DCACHE_DISCONNECTED.  They are placed on the
per-superblock list (->s_roots), so they can be located at umount
time for eviction purposes.”…””}”(hjº  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KKhj¶  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj  h²hh³hÊh´NubjC  )”}”(hX  Helper routines to allocate anonymous dentries, and to help attach
loose directory dentries at lookup time. They are:

 d_obtain_alias(inode) will return a dentry for the given inode.
   If the inode already has a dentry, one of those is returned.

   If it doesn't, a new anonymous (IS_ROOT and
   DCACHE_DISCONNECTED) dentry is allocated and attached.

   In the case of a directory, care is taken that only one dentry
   can ever be attached.

 d_splice_alias(inode, dentry) will introduce a new dentry into the tree;
   either the passed-in dentry or a preexisting alias for the given inode
   (such as an anonymous one created by d_obtain_alias), if appropriate.
   It returns NULL when the passed-in dentry is used, following the calling
   convention of ->lookup.
”h]”(hÝ)”}”(hŒuHelper routines to allocate anonymous dentries, and to help attach
loose directory dentries at lookup time. They are:”h]”hŒuHelper routines to allocate anonymous dentries, and to help attach
loose directory dentries at lookup time. They are:”…””}”(hjÒ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KPhjÎ  ubhŒblock_quote”“”)”}”(hX  d_obtain_alias(inode) will return a dentry for the given inode.
  If the inode already has a dentry, one of those is returned.

  If it doesn't, a new anonymous (IS_ROOT and
  DCACHE_DISCONNECTED) dentry is allocated and attached.

  In the case of a directory, care is taken that only one dentry
  can ever be attached.

d_splice_alias(inode, dentry) will introduce a new dentry into the tree;
  either the passed-in dentry or a preexisting alias for the given inode
  (such as an anonymous one created by d_obtain_alias), if appropriate.
  It returns NULL when the passed-in dentry is used, following the calling
  convention of ->lookup.
”h]”hŒdefinition_list”“”)”}”(hhh]”(hŒdefinition_list_item”“”)”}”(hX7  d_obtain_alias(inode) will return a dentry for the given inode.
If the inode already has a dentry, one of those is returned.

If it doesn't, a new anonymous (IS_ROOT and
DCACHE_DISCONNECTED) dentry is allocated and attached.

In the case of a directory, care is taken that only one dentry
can ever be attached.
”h]”(hŒterm”“”)”}”(hŒ?d_obtain_alias(inode) will return a dentry for the given inode.”h]”hŒ?d_obtain_alias(inode) will return a dentry for the given inode.”…””}”(hjó  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´KZhjí  ubhŒ
definition”“”)”}”(hhh]”(hÝ)”}”(hŒ<If the inode already has a dentry, one of those is returned.”h]”hŒ<If the inode already has a dentry, one of those is returned.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KThj  ubhÝ)”}”(hŒbIf it doesn't, a new anonymous (IS_ROOT and
DCACHE_DISCONNECTED) dentry is allocated and attached.”h]”hŒdIf it doesnâ€™t, a new anonymous (IS_ROOT and
DCACHE_DISCONNECTED) dentry is allocated and attached.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KVhj  ubhÝ)”}”(hŒTIn the case of a directory, care is taken that only one dentry
can ever be attached.”h]”hŒTIn the case of a directory, care is taken that only one dentry
can ever be attached.”…””}”(hj"  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KYhj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j  hjí  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´KZhjè  ubjì  )”}”(hX7  d_splice_alias(inode, dentry) will introduce a new dentry into the tree;
either the passed-in dentry or a preexisting alias for the given inode
(such as an anonymous one created by d_obtain_alias), if appropriate.
It returns NULL when the passed-in dentry is used, following the calling
convention of ->lookup.
”h]”(jò  )”}”(hŒHd_splice_alias(inode, dentry) will introduce a new dentry into the tree;”h]”hŒHd_splice_alias(inode, dentry) will introduce a new dentry into the tree;”…””}”(hj@  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´K`hj<  ubj  )”}”(hhh]”hÝ)”}”(hŒíeither the passed-in dentry or a preexisting alias for the given inode
(such as an anonymous one created by d_obtain_alias), if appropriate.
It returns NULL when the passed-in dentry is used, following the calling
convention of ->lookup.”h]”hŒíeither the passed-in dentry or a preexisting alias for the given inode
(such as an anonymous one created by d_obtain_alias), if appropriate.
It returns NULL when the passed-in dentry is used, following the calling
convention of ->lookup.”…””}”(hjQ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K]hjN  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj<  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´K`hjè  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jæ  hjâ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jà  h³hÊh´KShjÎ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj  h²hh³hÊh´Nubeh}”(h]”h ]”h"]”h$]”h&]”jz  Œ
loweralpha”j|  hj}  j~  uh1j=  hj  h²hh³hÊh´K8ubeh}”(h]”Œdcache-issues”ah ]”h"]”Œdcache issues”ah$]”h&]”uh1hµhh·h²hh³hÊh´K ubh¶)”}”(hhh]”(h»)”}”(hŒFilesystem Issues”h]”hŒFilesystem Issues”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjŒ  h²hh³hÊh´KcubhÝ)”}”(hŒ*For a filesystem to be exportable it must:”h]”hŒ*For a filesystem to be exportable it must:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KehjŒ  h²hubjá  )”}”(hXá  1. provide the filehandle fragment routines described below.
2. make sure that d_splice_alias is used rather than d_add
   when ->lookup finds an inode for a given parent and name.

   If inode is NULL, d_splice_alias(inode, dentry) is equivalent to::

             d_add(dentry, inode), NULL

   Similarly, d_splice_alias(ERR_PTR(err), dentry) = ERR_PTR(err)

   Typically the ->lookup routine will simply end with a::

             return d_splice_alias(inode, dentry);
     }


”h]”j>  )”}”(hhh]”(jC  )”}”(hŒ9provide the filehandle fragment routines described below.”h]”hÝ)”}”(hj´  h]”hŒ9provide the filehandle fragment routines described below.”…””}”(hj¶  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kghj²  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj¯  ubjC  )”}”(hXŒ  make sure that d_splice_alias is used rather than d_add
when ->lookup finds an inode for a given parent and name.

If inode is NULL, d_splice_alias(inode, dentry) is equivalent to::

          d_add(dentry, inode), NULL

Similarly, d_splice_alias(ERR_PTR(err), dentry) = ERR_PTR(err)

Typically the ->lookup routine will simply end with a::

          return d_splice_alias(inode, dentry);
  }


”h]”(hÝ)”}”(hŒqmake sure that d_splice_alias is used rather than d_add
when ->lookup finds an inode for a given parent and name.”h]”hŒqmake sure that d_splice_alias is used rather than d_add
when ->lookup finds an inode for a given parent and name.”…””}”(hjÍ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KhhjÉ  ubhÝ)”}”(hŒBIf inode is NULL, d_splice_alias(inode, dentry) is equivalent to::”h]”hŒAIf inode is NULL, d_splice_alias(inode, dentry) is equivalent to:”…””}”(hjÛ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KkhjÉ  ubhŒliteral_block”“”)”}”(hŒd_add(dentry, inode), NULL”h]”hŒd_add(dentry, inode), NULL”…””}”hjë  sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1jé  h³hÊh´KmhjÉ  ubhÝ)”}”(hŒ>Similarly, d_splice_alias(ERR_PTR(err), dentry) = ERR_PTR(err)”h]”hŒ>Similarly, d_splice_alias(ERR_PTR(err), dentry) = ERR_PTR(err)”…””}”(hjû  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KohjÉ  ubhÝ)”}”(hŒ7Typically the ->lookup routine will simply end with a::”h]”hŒ6Typically the ->lookup routine will simply end with a:”…””}”(hj	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KqhjÉ  ubjê  )”}”(hŒ/        return d_splice_alias(inode, dentry);
}”h]”hŒ/        return d_splice_alias(inode, dentry);
}”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”jù  jú  uh1jé  h³hÊh´KshjÉ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj¯  ubeh}”(h]”h ]”h"]”h$]”h&]”jz  j{  j|  hj}  j~  uh1j=  hj«  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jà  h³hÊh´KghjŒ  h²hubhÝ)”}”(hŒçA file system implementation declares that instances of the filesystem
are exportable by setting the s_export_op field in the struct
super_block.  This field must point to a struct export_operations
which has the following members:”h]”hŒçA file system implementation declares that instances of the filesystem
are exportable by setting the s_export_op field in the struct
super_block.  This field must point to a struct export_operations
which has the following members:”…””}”(hj7  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KxhjŒ  h²hubh Œindex”“”)”}”(hhh]”h}”(h]”h ]”h"]”h$]”h&]”Œentries”]”(Œsingle”Œexport_operations (C struct)”Œc.export_operations”hNt”auh1jE  hjŒ  h²hh³Nh´Nubh Œdesc”“”)”}”(hhh]”(h Œdesc_signature”“”)”}”(hŒexport_operations”h]”h Œdesc_signature_line”“”)”}”(hŒstruct export_operations”h]”(h Œdesc_sig_keyword”“”)”}”(hŒstruct”h]”hŒstruct”…””}”(hji  h²hh³Nh´Nubah}”(h]”h ]”Œk”ah"]”h$]”h&]”uh1jg  hjc  h²hh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Kubh Œdesc_sig_space”“”)”}”(hŒ ”h]”hŒ ”…””}”(hj{  h²hh³Nh´Nubah}”(h]”h ]”Œw”ah"]”h$]”h&]”uh1jy  hjc  h²hh³jx  h´Kubh Œ	desc_name”“”)”}”(hŒexport_operations”h]”h Œdesc_sig_name”“”)”}”(hj_  h]”hŒexport_operations”…””}”(hj’  h²hh³Nh´Nubah}”(h]”h ]”Œn”ah"]”h$]”h&]”uh1j  hjŒ  ubah}”(h]”h ]”(Œsig-name”Œdescname”eh"]”h$]”h&]”jù  jú  uh1jŠ  hjc  h²hh³jx  h´Kubeh}”(h]”h ]”h"]”h$]”h&]”jù  jú  Œadd_permalink”ˆuh1ja  Œsphinx_line_type”Œ
declarator”hj]  h²hh³jx  h´Kubah}”(h]”jT  ah ]”(Œsig”Œ
sig-object”eh"]”h$]”h&]”Œis_multiline”ˆŒ
_toc_parts”)Œ	_toc_name”huh1j[  h³jx  h´KhjX  h²hubh Œdesc_content”“”)”}”(hhh]”hÝ)”}”(hŒ)for nfsd to communicate with file systems”h]”hŒ)for nfsd to communicate with file systems”…””}”(hjÁ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÃhj¾  h²hubah}”(h]”h ]”h"]”h$]”h&]”uh1j¼  hjX  h²hh³jx  h´Kubeh}”(h]”h ]”(Œc”Œstruct”eh"]”h$]”h&]”Œdomain”jÙ  Œobjtype”jÚ  Œdesctype”jÚ  Œnoindex”‰Œnoindexentry”‰Œnocontentsentry”‰uh1jV  h²hhjŒ  h³Nh´NubhŒ	container”“”)”}”(hXä  **Definition**::

  struct export_operations {
      int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, struct inode *parent);
      struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, int fh_len, int fh_type);
      struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, int fh_len, int fh_type);
      int (*get_name)(struct dentry *parent, char *name, struct dentry *child);
      struct dentry * (*get_parent)(struct dentry *child);
      int (*commit_metadata)(struct inode *inode);
      int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
      int (*map_blocks)(struct inode *inode, loff_t offset, u64 len, struct iomap *iomap, bool write, u32 *device_generation);
      int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, int nr_iomaps, struct iattr *iattr);
      int (*permission)(struct handle_to_path_ctx *ctx, unsigned int oflags);
      struct file * (*open)(const struct path *path, unsigned int oflags);
  #define EXPORT_OP_NOWCC                 (0x1) ;
  #define EXPORT_OP_NOSUBTREECHK          (0x2) ;
  #define EXPORT_OP_CLOSE_BEFORE_UNLINK   (0x4) ;
  #define EXPORT_OP_REMOTE_FS             (0x8) ;
  #define EXPORT_OP_NOATOMIC_ATTR         (0x10)  #define EXPORT_OP_FLUSH_ON_CLOSE        (0x20) ;
  #define EXPORT_OP_NOLOCKS               (0x40) ;
      unsigned long   flags;
  };

**Members**

``encode_fh``
  **encode_fh** should store in the file handle fragment **fh** (using at most
  **max_len** bytes) information that can be used by **decode_fh** to recover the
  file referred to by the :c:type:`struct dentry <dentry>` **de**.  If **flag** has CONNECTABLE bit
  set, the encode_fh() should store sufficient information so that a good
  attempt can be made to find not only the file but also it's place in the
  filesystem.   This typically means storing a reference to de->d_parent in
  the filehandle fragment.  encode_fh() should return the fileid_type on
  success and on error returns 255 (if the space needed to encode fh is
  greater than **max_len***4 bytes). On error **max_len** contains the minimum
  size(in 4 byte unit) needed to encode the file handle.

``fh_to_dentry``
  **fh_to_dentry** is given a :c:type:`struct super_block <super_block>` (**sb**) and a file handle
  fragment (**fh**, **fh_len**). It should return a :c:type:`struct dentry <dentry>` which refers
  to the same file that the file handle fragment refers to.  If it cannot,
  it should return a ``NULL`` pointer if the file cannot be found, or an
  ``ERR_PTR`` error code of ``ENOMEM`` if a memory allocation failure occurred.
  Any other error code is treated like ``NULL``, and will cause an ``ESTALE`` error
  for callers of exportfs_decode_fh().
  Any suitable dentry can be returned including, if necessary, a new dentry
  created with d_alloc_root.  The caller can then find any other extant
  dentries by following the d_alias links.

``fh_to_parent``
  Same as **fh_to_dentry**, except that it returns a pointer to the parent
  dentry if it was encoded into the filehandle fragment by **encode_fh**.

``get_name``
  **get_name** should find a name for the given **child** in the given **parent**
  directory.  The name should be stored in the **name** (with the
  understanding that it is already pointing to a ``NAME_MAX`` + 1 sized
  buffer.   get_name() should return ``0`` on success, a negative error code
  or error.  **get_name** will be called without **parent->i_rwsem** held.

``get_parent``
  **get_parent** should find the parent directory for the given **child** which
  is also a directory.  In the event that it cannot be found, or storage
  space cannot be allocated, a ``ERR_PTR`` should be returned.

``commit_metadata``
  **commit_metadata** should commit metadata changes to stable storage.

``get_uuid``
  Get a filesystem unique signature exposed to clients.

``map_blocks``
  Map and, if necessary, allocate blocks for a layout.

``commit_blocks``
  Commit blocks in a layout once the client is done with them.

``permission``
  Allow filesystems to specify a custom permission function for the
  open_by_handle_at(2) syscall instead of the default permission check.
  This custom permission function is not respected by nfsd.

``open``
  Allow filesystems to specify a custom open function for the
  open_by_handle_at(2) syscall instead of the default file_open_root().
  This custom open function is not respected by nfsd.

``flags``
  Allows the filesystem to communicate to nfsd that it may want to do things
  differently when dealing with it.”h]”(hÝ)”}”(hŒ**Definition**::”h]”(hŒstrong”“”)”}”(hŒ**Definition**”h]”hŒ
Definition”…””}”(hjð  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjê  ubhŒ:”…””}”(hjê  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÇhjæ  ubjê  )”}”(hX2  struct export_operations {
    int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, struct inode *parent);
    struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, int fh_len, int fh_type);
    struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, int fh_len, int fh_type);
    int (*get_name)(struct dentry *parent, char *name, struct dentry *child);
    struct dentry * (*get_parent)(struct dentry *child);
    int (*commit_metadata)(struct inode *inode);
    int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
    int (*map_blocks)(struct inode *inode, loff_t offset, u64 len, struct iomap *iomap, bool write, u32 *device_generation);
    int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, int nr_iomaps, struct iattr *iattr);
    int (*permission)(struct handle_to_path_ctx *ctx, unsigned int oflags);
    struct file * (*open)(const struct path *path, unsigned int oflags);
#define EXPORT_OP_NOWCC                 (0x1) ;
#define EXPORT_OP_NOSUBTREECHK          (0x2) ;
#define EXPORT_OP_CLOSE_BEFORE_UNLINK   (0x4) ;
#define EXPORT_OP_REMOTE_FS             (0x8) ;
#define EXPORT_OP_NOATOMIC_ATTR         (0x10)  #define EXPORT_OP_FLUSH_ON_CLOSE        (0x20) ;
#define EXPORT_OP_NOLOCKS               (0x40) ;
    unsigned long   flags;
};”h]”hX2  struct export_operations {
    int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len, struct inode *parent);
    struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid, int fh_len, int fh_type);
    struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid, int fh_len, int fh_type);
    int (*get_name)(struct dentry *parent, char *name, struct dentry *child);
    struct dentry * (*get_parent)(struct dentry *child);
    int (*commit_metadata)(struct inode *inode);
    int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
    int (*map_blocks)(struct inode *inode, loff_t offset, u64 len, struct iomap *iomap, bool write, u32 *device_generation);
    int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, int nr_iomaps, struct iattr *iattr);
    int (*permission)(struct handle_to_path_ctx *ctx, unsigned int oflags);
    struct file * (*open)(const struct path *path, unsigned int oflags);
#define EXPORT_OP_NOWCC                 (0x1) ;
#define EXPORT_OP_NOSUBTREECHK          (0x2) ;
#define EXPORT_OP_CLOSE_BEFORE_UNLINK   (0x4) ;
#define EXPORT_OP_REMOTE_FS             (0x8) ;
#define EXPORT_OP_NOATOMIC_ATTR         (0x10)  #define EXPORT_OP_FLUSH_ON_CLOSE        (0x20) ;
#define EXPORT_OP_NOLOCKS               (0x40) ;
    unsigned long   flags;
};”…””}”hj	  sbah}”(h]”h ]”h"]”h$]”h&]”jù  jú  uh1jé  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÉhjæ  ubhÝ)”}”(hŒ**Members**”h]”jï  )”}”(hj  h]”hŒMembers”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÞhjæ  ubjç  )”}”(hhh]”(jì  )”}”(hXù  ``encode_fh``
**encode_fh** should store in the file handle fragment **fh** (using at most
**max_len** bytes) information that can be used by **decode_fh** to recover the
file referred to by the :c:type:`struct dentry <dentry>` **de**.  If **flag** has CONNECTABLE bit
set, the encode_fh() should store sufficient information so that a good
attempt can be made to find not only the file but also it's place in the
filesystem.   This typically means storing a reference to de->d_parent in
the filehandle fragment.  encode_fh() should return the fileid_type on
success and on error returns 255 (if the space needed to encode fh is
greater than **max_len***4 bytes). On error **max_len** contains the minimum
size(in 4 byte unit) needed to encode the file handle.
”h]”(jò  )”}”(hŒ``encode_fh``”h]”hŒliteral”“”)”}”(hj9  h]”hŒ	encode_fh”…””}”(hj=  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj7  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÜhj3  ubj  )”}”(hhh]”hÝ)”}”(hXê  **encode_fh** should store in the file handle fragment **fh** (using at most
**max_len** bytes) information that can be used by **decode_fh** to recover the
file referred to by the :c:type:`struct dentry <dentry>` **de**.  If **flag** has CONNECTABLE bit
set, the encode_fh() should store sufficient information so that a good
attempt can be made to find not only the file but also it's place in the
filesystem.   This typically means storing a reference to de->d_parent in
the filehandle fragment.  encode_fh() should return the fileid_type on
success and on error returns 255 (if the space needed to encode fh is
greater than **max_len***4 bytes). On error **max_len** contains the minimum
size(in 4 byte unit) needed to encode the file handle.”h]”(jï  )”}”(hŒ**encode_fh**”h]”hŒ	encode_fh”…””}”(hjX  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒ* should store in the file handle fragment ”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ**fh**”h]”hŒfh”…””}”(hjj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒ (using at most
”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ**max_len**”h]”hŒmax_len”…””}”(hj|  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒ( bytes) information that can be used by ”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ**decode_fh**”h]”hŒ	decode_fh”…””}”(hjŽ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒ( to recover the
file referred to by the ”…””}”(hjT  h²hh³Nh´Nubh)”}”(hŒ :c:type:`struct dentry <dentry>`”h]”j<  )”}”(hj¢  h]”hŒstruct dentry”…””}”(hj¤  h²hh³Nh´Nubah}”(h]”h ]”(Œxref”jÙ  Œc-type”eh"]”h$]”h&]”uh1j;  hj   ubah}”(h]”h ]”h"]”h$]”h&]”Œrefdoc”Œfilesystems/nfs/exporting”Œ	refdomain”jÙ  Œreftype”Œtype”Œrefexplicit”ˆŒrefwarn”‰Œc:parent_key”Œsphinx.domains.c”Œ	LookupKey”“”)”}”Œdata”]”sbŒ	reftarget”Œdentry”uh1hh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÓhjT  ubhŒ ”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ**de**”h]”hŒde”…””}”(hjÏ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒ.  If ”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ**flag**”h]”hŒflag”…””}”(hjá  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhXŒ   has CONNECTABLE bit
set, the encode_fh() should store sufficient information so that a good
attempt can be made to find not only the file but also itâ€™s place in the
filesystem.   This typically means storing a reference to de->d_parent in
the filehandle fragment.  encode_fh() should return the fileid_type on
success and on error returns 255 (if the space needed to encode fh is
greater than ”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ***max_len***4 bytes). On error **max_len**”h]”hŒ&max_len***4 bytes). On error **max_len”…””}”(hjó  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒL contains the minimum
size(in 4 byte unit) needed to encode the file handle.”…””}”(hjT  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³jÊ  h´KÓhjQ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj3  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³jP  h´KÜhj0  ubjì  )”}”(hXá  ``fh_to_dentry``
**fh_to_dentry** is given a :c:type:`struct super_block <super_block>` (**sb**) and a file handle
fragment (**fh**, **fh_len**). It should return a :c:type:`struct dentry <dentry>` which refers
to the same file that the file handle fragment refers to.  If it cannot,
it should return a ``NULL`` pointer if the file cannot be found, or an
``ERR_PTR`` error code of ``ENOMEM`` if a memory allocation failure occurred.
Any other error code is treated like ``NULL``, and will cause an ``ESTALE`` error
for callers of exportfs_decode_fh().
Any suitable dentry can be returned including, if necessary, a new dentry
created with d_alloc_root.  The caller can then find any other extant
dentries by following the d_alias links.
”h]”(jò  )”}”(hŒ``fh_to_dentry``”h]”j<  )”}”(hj  h]”hŒfh_to_dentry”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Kèhj  ubj  )”}”(hhh]”hÝ)”}”(hXÏ  **fh_to_dentry** is given a :c:type:`struct super_block <super_block>` (**sb**) and a file handle
fragment (**fh**, **fh_len**). It should return a :c:type:`struct dentry <dentry>` which refers
to the same file that the file handle fragment refers to.  If it cannot,
it should return a ``NULL`` pointer if the file cannot be found, or an
``ERR_PTR`` error code of ``ENOMEM`` if a memory allocation failure occurred.
Any other error code is treated like ``NULL``, and will cause an ``ESTALE`` error
for callers of exportfs_decode_fh().
Any suitable dentry can be returned including, if necessary, a new dentry
created with d_alloc_root.  The caller can then find any other extant
dentries by following the d_alias links.”h]”(jï  )”}”(hŒ**fh_to_dentry**”h]”hŒfh_to_dentry”…””}”(hj:  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj6  ubhŒ is given a ”…””}”(hj6  h²hh³Nh´Nubh)”}”(hŒ*:c:type:`struct super_block <super_block>`”h]”j<  )”}”(hjN  h]”hŒstruct super_block”…””}”(hjP  h²hh³Nh´Nubah}”(h]”h ]”(j®  jÙ  Œc-type”eh"]”h$]”h&]”uh1j;  hjL  ubah}”(h]”h ]”h"]”h$]”h&]”Œrefdoc”jº  Œ	refdomain”jÙ  Œreftype”Œtype”Œrefexplicit”ˆŒrefwarn”‰jÀ  jÄ  jÈ  Œsuper_block”uh1hh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Kßhj6  ubhŒ (”…””}”(hj6  h²hh³Nh´Nubjï  )”}”(hŒ**sb**”h]”hŒsb”…””}”(hjp  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj6  ubhŒ) and a file handle
fragment (”…””}”(hj6  h²hh³Nh´Nubjï  )”}”(hŒ**fh**”h]”hŒfh”…””}”(hj‚  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj6  ubhŒ, ”…””}”(hj6  h²hh³Nh´Nubjï  )”}”(hŒ
**fh_len**”h]”hŒfh_len”…””}”(hj”  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj6  ubhŒ). It should return a ”…””}”(hj6  h²hh³Nh´Nubh)”}”(hŒ :c:type:`struct dentry <dentry>`”h]”j<  )”}”(hj¨  h]”hŒstruct dentry”…””}”(hjª  h²hh³Nh´Nubah}”(h]”h ]”(j®  jÙ  Œc-type”eh"]”h$]”h&]”uh1j;  hj¦  ubah}”(h]”h ]”h"]”h$]”h&]”Œrefdoc”jº  Œ	refdomain”jÙ  Œreftype”Œtype”Œrefexplicit”ˆŒrefwarn”‰jÀ  jÄ  jÈ  Œdentry”uh1hh³jk  h´Kßhj6  ubhŒj which refers
to the same file that the file handle fragment refers to.  If it cannot,
it should return a ”…””}”(hj6  h²hh³Nh´Nubj<  )”}”(hŒ``NULL``”h]”hŒNULL”…””}”(hjÉ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj6  ubhŒ, pointer if the file cannot be found, or an
”…””}”(hj6  h²hh³Nh´Nubj<  )”}”(hŒ``ERR_PTR``”h]”hŒERR_PTR”…””}”(hjÛ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj6  ubhŒ error code of ”…””}”(hj6  h²hh³Nh´Nubj<  )”}”(hŒ
``ENOMEM``”h]”hŒENOMEM”…””}”(hjí  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj6  ubhŒO if a memory allocation failure occurred.
Any other error code is treated like ”…””}”(hj6  h²hh³Nh´Nubj<  )”}”(hŒ``NULL``”h]”hŒNULL”…””}”(hjÿ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj6  ubhŒ, and will cause an ”…””}”(hj6  h²hh³Nh´Nubj<  )”}”(hŒ
``ESTALE``”h]”hŒESTALE”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj6  ubhŒä error
for callers of exportfs_decode_fh().
Any suitable dentry can be returned including, if necessary, a new dentry
created with d_alloc_root.  The caller can then find any other extant
dentries by following the d_alias links.”…””}”(hj6  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³jk  h´Kßhj3  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³j2  h´Kèhj0  ubjì  )”}”(hŒ¢``fh_to_parent``
Same as **fh_to_dentry**, except that it returns a pointer to the parent
dentry if it was encoded into the filehandle fragment by **encode_fh**.
”h]”(jò  )”}”(hŒ``fh_to_parent``”h]”j<  )”}”(hj;  h]”hŒfh_to_parent”…””}”(hj=  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj9  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Kìhj5  ubj  )”}”(hhh]”hÝ)”}”(hŒSame as **fh_to_dentry**, except that it returns a pointer to the parent
dentry if it was encoded into the filehandle fragment by **encode_fh**.”h]”(hŒSame as ”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ**fh_to_dentry**”h]”hŒfh_to_dentry”…””}”(hj\  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒj, except that it returns a pointer to the parent
dentry if it was encoded into the filehandle fragment by ”…””}”(hjT  h²hh³Nh´Nubjï  )”}”(hŒ**encode_fh**”h]”hŒ	encode_fh”…””}”(hjn  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjT  ubhŒ.”…””}”(hjT  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KëhjQ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj5  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³jP  h´Kìhj0  ubjì  )”}”(hXw  ``get_name``
**get_name** should find a name for the given **child** in the given **parent**
directory.  The name should be stored in the **name** (with the
understanding that it is already pointing to a ``NAME_MAX`` + 1 sized
buffer.   get_name() should return ``0`` on success, a negative error code
or error.  **get_name** will be called without **parent->i_rwsem** held.
”h]”(jò  )”}”(hŒ``get_name``”h]”j<  )”}”(hj™  h]”hŒget_name”…””}”(hj›  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj—  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Kóhj“  ubj  )”}”(hhh]”hÝ)”}”(hXi  **get_name** should find a name for the given **child** in the given **parent**
directory.  The name should be stored in the **name** (with the
understanding that it is already pointing to a ``NAME_MAX`` + 1 sized
buffer.   get_name() should return ``0`` on success, a negative error code
or error.  **get_name** will be called without **parent->i_rwsem** held.”h]”(jï  )”}”(hŒ**get_name**”h]”hŒget_name”…””}”(hj¶  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj²  ubhŒ" should find a name for the given ”…””}”(hj²  h²hh³Nh´Nubjï  )”}”(hŒ	**child**”h]”hŒchild”…””}”(hjÈ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj²  ubhŒ in the given ”…””}”(hj²  h²hh³Nh´Nubjï  )”}”(hŒ
**parent**”h]”hŒparent”…””}”(hjÚ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj²  ubhŒ.
directory.  The name should be stored in the ”…””}”(hj²  h²hh³Nh´Nubjï  )”}”(hŒ**name**”h]”hŒname”…””}”(hjì  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj²  ubhŒ: (with the
understanding that it is already pointing to a ”…””}”(hj²  h²hh³Nh´Nubj<  )”}”(hŒ``NAME_MAX``”h]”hŒNAME_MAX”…””}”(hjþ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj²  ubhŒ. + 1 sized
buffer.   get_name() should return ”…””}”(hj²  h²hh³Nh´Nubj<  )”}”(hŒ``0``”h]”hŒ0”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj²  ubhŒ. on success, a negative error code
or error.  ”…””}”(hj²  h²hh³Nh´Nubjï  )”}”(hŒ**get_name**”h]”hŒget_name”…””}”(hj"  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj²  ubhŒ will be called without ”…””}”(hj²  h²hh³Nh´Nubjï  )”}”(hŒ**parent->i_rwsem**”h]”hŒparent->i_rwsem”…””}”(hj4  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj²  ubhŒ held.”…””}”(hj²  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Kïhj¯  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj“  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³j®  h´Kóhj0  ubjì  )”}”(hŒá``get_parent``
**get_parent** should find the parent directory for the given **child** which
is also a directory.  In the event that it cannot be found, or storage
space cannot be allocated, a ``ERR_PTR`` should be returned.
”h]”(jò  )”}”(hŒ``get_parent``”h]”j<  )”}”(hj_  h]”hŒ
get_parent”…””}”(hja  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj]  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KøhjY  ubj  )”}”(hhh]”hÝ)”}”(hŒÑ**get_parent** should find the parent directory for the given **child** which
is also a directory.  In the event that it cannot be found, or storage
space cannot be allocated, a ``ERR_PTR`` should be returned.”h]”(jï  )”}”(hŒ**get_parent**”h]”hŒ
get_parent”…””}”(hj|  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjx  ubhŒ0 should find the parent directory for the given ”…””}”(hjx  h²hh³Nh´Nubjï  )”}”(hŒ	**child**”h]”hŒchild”…””}”(hjŽ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjx  ubhŒk which
is also a directory.  In the event that it cannot be found, or storage
space cannot be allocated, a ”…””}”(hjx  h²hh³Nh´Nubj<  )”}”(hŒ``ERR_PTR``”h]”hŒERR_PTR”…””}”(hj   h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hjx  ubhŒ should be returned.”…””}”(hjx  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Köhju  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjY  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³jt  h´Køhj0  ubjì  )”}”(hŒZ``commit_metadata``
**commit_metadata** should commit metadata changes to stable storage.
”h]”(jò  )”}”(hŒ``commit_metadata``”h]”j<  )”}”(hjË  h]”hŒcommit_metadata”…””}”(hjÍ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hjÉ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´MhjÅ  ubj  )”}”(hhh]”hÝ)”}”(hŒE**commit_metadata** should commit metadata changes to stable storage.”h]”(jï  )”}”(hŒ**commit_metadata**”h]”hŒcommit_metadata”…””}”(hjè  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjä  ubhŒ2 should commit metadata changes to stable storage.”…””}”(hjä  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³jà  h´Mhjá  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjÅ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³jà  h´Mhj0  ubjì  )”}”(hŒC``get_uuid``
Get a filesystem unique signature exposed to clients.
”h]”(jò  )”}”(hŒ``get_uuid``”h]”j<  )”}”(hj  h]”hŒget_uuid”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Mhj  ubj  )”}”(hhh]”hÝ)”}”(hŒ5Get a filesystem unique signature exposed to clients.”h]”hŒ5Get a filesystem unique signature exposed to clients.”…””}”(hj+  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³j'  h´Mhj(  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³j'  h´Mhj0  ubjì  )”}”(hŒD``map_blocks``
Map and, if necessary, allocate blocks for a layout.
”h]”(jò  )”}”(hŒ``map_blocks``”h]”j<  )”}”(hjK  h]”hŒ
map_blocks”…””}”(hjM  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hjI  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´MhjE  ubj  )”}”(hhh]”hÝ)”}”(hŒ4Map and, if necessary, allocate blocks for a layout.”h]”hŒ4Map and, if necessary, allocate blocks for a layout.”…””}”(hjd  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³j`  h´Mhja  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjE  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³j`  h´Mhj0  ubjì  )”}”(hŒO``commit_blocks``
Commit blocks in a layout once the client is done with them.
”h]”(jò  )”}”(hŒ``commit_blocks``”h]”j<  )”}”(hj„  h]”hŒcommit_blocks”…””}”(hj†  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj‚  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Mhj~  ubj  )”}”(hhh]”hÝ)”}”(hŒ<Commit blocks in a layout once the client is done with them.”h]”hŒ<Commit blocks in a layout once the client is done with them.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³j™  h´Mhjš  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj~  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³j™  h´Mhj0  ubjì  )”}”(hŒÑ``permission``
Allow filesystems to specify a custom permission function for the
open_by_handle_at(2) syscall instead of the default permission check.
This custom permission function is not respected by nfsd.
”h]”(jò  )”}”(hŒ``permission``”h]”j<  )”}”(hj½  h]”hŒ
permission”…””}”(hj¿  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj»  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Kýhj·  ubj  )”}”(hhh]”hÝ)”}”(hŒÁAllow filesystems to specify a custom permission function for the
open_by_handle_at(2) syscall instead of the default permission check.
This custom permission function is not respected by nfsd.”h]”hŒÁAllow filesystems to specify a custom permission function for the
open_by_handle_at(2) syscall instead of the default permission check.
This custom permission function is not respected by nfsd.”…””}”(hjÖ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KûhjÓ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj·  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³jÒ  h´Kýhj0  ubjì  )”}”(hŒ¿``open``
Allow filesystems to specify a custom open function for the
open_by_handle_at(2) syscall instead of the default file_open_root().
This custom open function is not respected by nfsd.
”h]”(jò  )”}”(hŒ``open``”h]”j<  )”}”(hj÷  h]”hŒopen”…””}”(hjù  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hjõ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Mhjñ  ubj  )”}”(hhh]”hÝ)”}”(hŒµAllow filesystems to specify a custom open function for the
open_by_handle_at(2) syscall instead of the default file_open_root().
This custom open function is not respected by nfsd.”h]”hŒµAllow filesystems to specify a custom open function for the
open_by_handle_at(2) syscall instead of the default file_open_root().
This custom open function is not respected by nfsd.”…””}”(hj	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´M hj	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjñ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³j	  h´Mhj0  ubjì  )”}”(hŒv``flags``
Allows the filesystem to communicate to nfsd that it may want to do things
differently when dealing with it.”h]”(jò  )”}”(hŒ	``flags``”h]”j<  )”}”(hj1	  h]”hŒflags”…””}”(hj3	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j;  hj/	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´Mhj+	  ubj  )”}”(hhh]”hÝ)”}”(hŒlAllows the filesystem to communicate to nfsd that it may want to do things
differently when dealing with it.”h]”hŒlAllows the filesystem to communicate to nfsd that it may want to do things
differently when dealing with it.”…””}”(hjJ	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³jF	  h´MhjG	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj+	  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³jF	  h´Mhj0  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jæ  hjæ  ubeh}”(h]”h ]”Œkernelindent”ah"]”h$]”h&]”uh1jä  hjŒ  h²hh³Nh´NubhÝ)”}”(hŒ**Description**”h]”jï  )”}”(hjs	  h]”hŒDescription”…””}”(hju	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjq	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´MhjŒ  h²hubhÝ)”}”(hŒGMethods for open_by_handle(2) syscall with special kernel file systems:”h]”hŒGMethods for open_by_handle(2) syscall with special kernel file systems:”…””}”(hj‰	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÊhjŒ  h²hubhÝ)”}”(hŒƒSee Documentation/filesystems/nfs/exporting.rst for details on how to use
this interface correctly and the definition of the flags.”h]”hŒƒSee Documentation/filesystems/nfs/exporting.rst for details on how to use
this interface correctly and the definition of the flags.”…””}”(hj˜	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÌhjŒ  h²hubjç  )”}”(hhh]”jì  )”}”(hŒxLocking rules:
get_parent is called with child->d_inode->i_rwsem down
get_name is not (which is possibly inconsistent)

”h]”(jò  )”}”(hŒLocking rules:”h]”hŒLocking rules:”…””}”(hj®	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÓhjª	  ubj  )”}”(hhh]”hÝ)”}”(hŒgget_parent is called with child->d_inode->i_rwsem down
get_name is not (which is possibly inconsistent)”h]”hŒgget_parent is called with child->d_inode->i_rwsem down
get_name is not (which is possibly inconsistent)”…””}”(hjÀ	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³Œc/var/lib/git/docbuild/linux/Documentation/filesystems/nfs/exporting:125: ./include/linux/exportfs.h”h´KÑhj½	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjª	  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³j¼	  h´KÓhj§	  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jæ  hjŒ  h²hh³Nh´NubhÝ)”}”(hXÑ  A filehandle fragment consists of an array of 1 or more 4byte words,
together with a one byte "type".
The decode_fh routine should not depend on the stated size that is
passed to it.  This size may be larger than the original filehandle
generated by encode_fh, in which case it will have been padded with
nuls.  Rather, the encode_fh routine should choose a "type" which
indicates the decode_fh how much of the filehandle is valid, and how
it should be interpreted.”h]”hXÙ  A filehandle fragment consists of an array of 1 or more 4byte words,
together with a one byte â€œtypeâ€.
The decode_fh routine should not depend on the stated size that is
passed to it.  This size may be larger than the original filehandle
generated by encode_fh, in which case it will have been padded with
nuls.  Rather, the encode_fh routine should choose a â€œtypeâ€ which
indicates the decode_fh how much of the filehandle is valid, and how
it should be interpreted.”…””}”(hjá	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K€hjŒ  h²hubeh}”(h]”Œfilesystem-issues”ah ]”h"]”Œfilesystem issues”ah$]”h&]”uh1hµhh·h²hh³hÊh´Kcubh¶)”}”(hhh]”(h»)”}”(hŒExport Operations Flags”h]”hŒExport Operations Flags”…””}”(hjú	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj÷	  h²hh³hÊh´KŠubhÝ)”}”(hŒ÷In addition to the operation vector pointers, struct export_operations also
contains a "flags" field that allows the filesystem to communicate to nfsd
that it may want to do things differently when dealing with it. The
following flags are defined:”h]”hŒûIn addition to the operation vector pointers, struct export_operations also
contains a â€œflagsâ€ field that allows the filesystem to communicate to nfsd
that it may want to do things differently when dealing with it. The
following flags are defined:”…””}”(hj
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K‹hj÷	  h²hubjá  )”}”(hX_  EXPORT_OP_NOWCC - disable NFSv3 WCC attributes on this filesystem
  RFC 1813 recommends that servers always send weak cache consistency
  (WCC) data to the client after each operation. The server should
  atomically collect attributes about the inode, do an operation on it,
  and then collect the attributes afterward. This allows the client to
  skip issuing GETATTRs in some situations but means that the server
  is calling vfs_getattr for almost all RPCs. On some filesystems
  (particularly those that are clustered or networked) this is expensive
  and atomicity is difficult to guarantee. This flag indicates to nfsd
  that it should skip providing WCC attributes to the client in NFSv3
  replies when doing operations on this filesystem. Consider enabling
  this on filesystems that have an expensive ->getattr inode operation,
  or when atomicity between pre and post operation attribute collection
  is impossible to guarantee.

EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs
  Many NFS operations deal with filehandles, which the server must then
  vet to ensure that they live inside of an exported tree. When the
  export consists of an entire filesystem, this is trivial. nfsd can just
  ensure that the filehandle live on the filesystem. When only part of a
  filesystem is exported however, then nfsd must walk the ancestors of the
  inode to ensure that it's within an exported subtree. This is an
  expensive operation and not all filesystems can support it properly.
  This flag exempts the filesystem from subtree checking and causes
  exportfs to get back an error if it tries to enable subtree checking
  on it.

EXPORT_OP_CLOSE_BEFORE_UNLINK - always close cached files before unlinking
  On some exportable filesystems (such as NFS) unlinking a file that
  is still open can cause a fair bit of extra work. For instance,
  the NFS client will do a "sillyrename" to ensure that the file
  sticks around while it's still open. When reexporting, that open
  file is held by nfsd so we usually end up doing a sillyrename, and
  then immediately deleting the sillyrenamed file just afterward when
  the link count actually goes to zero. Sometimes this delete can race
  with other operations (for instance an rmdir of the parent directory).
  This flag causes nfsd to close any open files for this inode _before_
  calling into the vfs to do an unlink or a rename that would replace
  an existing file.

EXPORT_OP_REMOTE_FS - Backing storage for this filesystem is remote
  PF_LOCAL_THROTTLE exists for loopback NFSD, where a thread needs to
  write to one bdi (the final bdi) in order to free up writes queued
  to another bdi (the client bdi). Such threads get a private balance
  of dirty pages so that dirty pages for the client bdi do not imact
  the daemon writing to the final bdi. For filesystems whose durable
  storage is not local (such as exported NFS filesystems), this
  constraint has negative consequences. EXPORT_OP_REMOTE_FS enables
  an export to disable writeback throttling.

EXPORT_OP_NOATOMIC_ATTR - Filesystem does not update attributes atomically
  EXPORT_OP_NOATOMIC_ATTR indicates that the exported filesystem
  cannot provide the semantics required by the "atomic" boolean in
  NFSv4's change_info4. This boolean indicates to a client whether the
  returned before and after change attributes were obtained atomically
  with the respect to the requested metadata operation (UNLINK,
  OPEN/CREATE, MKDIR, etc).

EXPORT_OP_FLUSH_ON_CLOSE - Filesystem flushes file data on close(2)
  On most filesystems, inodes can remain under writeback after the
  file is closed. NFSD relies on client activity or local flusher
  threads to handle writeback. Certain filesystems, such as NFS, flush
  all of an inode's dirty data on last close. Exports that behave this
  way should set EXPORT_OP_FLUSH_ON_CLOSE so that NFSD knows to skip
  waiting for writeback when closing such files.
”h]”jç  )”}”(hhh]”(jì  )”}”(hX‘  EXPORT_OP_NOWCC - disable NFSv3 WCC attributes on this filesystem
RFC 1813 recommends that servers always send weak cache consistency
(WCC) data to the client after each operation. The server should
atomically collect attributes about the inode, do an operation on it,
and then collect the attributes afterward. This allows the client to
skip issuing GETATTRs in some situations but means that the server
is calling vfs_getattr for almost all RPCs. On some filesystems
(particularly those that are clustered or networked) this is expensive
and atomicity is difficult to guarantee. This flag indicates to nfsd
that it should skip providing WCC attributes to the client in NFSv3
replies when doing operations on this filesystem. Consider enabling
this on filesystems that have an expensive ->getattr inode operation,
or when atomicity between pre and post operation attribute collection
is impossible to guarantee.
”h]”(jò  )”}”(hŒAEXPORT_OP_NOWCC - disable NFSv3 WCC attributes on this filesystem”h]”hŒAEXPORT_OP_NOWCC - disable NFSv3 WCC attributes on this filesystem”…””}”(hj!
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´Khj
  ubj  )”}”(hhh]”hÝ)”}”(hXN  RFC 1813 recommends that servers always send weak cache consistency
(WCC) data to the client after each operation. The server should
atomically collect attributes about the inode, do an operation on it,
and then collect the attributes afterward. This allows the client to
skip issuing GETATTRs in some situations but means that the server
is calling vfs_getattr for almost all RPCs. On some filesystems
(particularly those that are clustered or networked) this is expensive
and atomicity is difficult to guarantee. This flag indicates to nfsd
that it should skip providing WCC attributes to the client in NFSv3
replies when doing operations on this filesystem. Consider enabling
this on filesystems that have an expensive ->getattr inode operation,
or when atomicity between pre and post operation attribute collection
is impossible to guarantee.”h]”hXN  RFC 1813 recommends that servers always send weak cache consistency
(WCC) data to the client after each operation. The server should
atomically collect attributes about the inode, do an operation on it,
and then collect the attributes afterward. This allows the client to
skip issuing GETATTRs in some situations but means that the server
is calling vfs_getattr for almost all RPCs. On some filesystems
(particularly those that are clustered or networked) this is expensive
and atomicity is difficult to guarantee. This flag indicates to nfsd
that it should skip providing WCC attributes to the client in NFSv3
replies when doing operations on this filesystem. Consider enabling
this on filesystems that have an expensive ->getattr inode operation,
or when atomicity between pre and post operation attribute collection
is impossible to guarantee.”…””}”(hj2
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K‘hj/
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´Khj
  ubjì  )”}”(hX²  EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs
Many NFS operations deal with filehandles, which the server must then
vet to ensure that they live inside of an exported tree. When the
export consists of an entire filesystem, this is trivial. nfsd can just
ensure that the filehandle live on the filesystem. When only part of a
filesystem is exported however, then nfsd must walk the ancestors of the
inode to ensure that it's within an exported subtree. This is an
expensive operation and not all filesystems can support it properly.
This flag exempts the filesystem from subtree checking and causes
exportfs to get back an error if it tries to enable subtree checking
on it.
”h]”(jò  )”}”(hŒ=EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs”h]”hŒ=EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs”…””}”(hjP
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´K©hjL
  ubj  )”}”(hhh]”hÝ)”}”(hXs  Many NFS operations deal with filehandles, which the server must then
vet to ensure that they live inside of an exported tree. When the
export consists of an entire filesystem, this is trivial. nfsd can just
ensure that the filehandle live on the filesystem. When only part of a
filesystem is exported however, then nfsd must walk the ancestors of the
inode to ensure that it's within an exported subtree. This is an
expensive operation and not all filesystems can support it properly.
This flag exempts the filesystem from subtree checking and causes
exportfs to get back an error if it tries to enable subtree checking
on it.”h]”hXu  Many NFS operations deal with filehandles, which the server must then
vet to ensure that they live inside of an exported tree. When the
export consists of an entire filesystem, this is trivial. nfsd can just
ensure that the filehandle live on the filesystem. When only part of a
filesystem is exported however, then nfsd must walk the ancestors of the
inode to ensure that itâ€™s within an exported subtree. This is an
expensive operation and not all filesystems can support it properly.
This flag exempts the filesystem from subtree checking and causes
exportfs to get back an error if it tries to enable subtree checking
on it.”…””}”(hja
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K hj^
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjL
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´K©hj
  ubjì  )”}”(hXý  EXPORT_OP_CLOSE_BEFORE_UNLINK - always close cached files before unlinking
On some exportable filesystems (such as NFS) unlinking a file that
is still open can cause a fair bit of extra work. For instance,
the NFS client will do a "sillyrename" to ensure that the file
sticks around while it's still open. When reexporting, that open
file is held by nfsd so we usually end up doing a sillyrename, and
then immediately deleting the sillyrenamed file just afterward when
the link count actually goes to zero. Sometimes this delete can race
with other operations (for instance an rmdir of the parent directory).
This flag causes nfsd to close any open files for this inode _before_
calling into the vfs to do an unlink or a rename that would replace
an existing file.
”• U      h]”(jò  )”}”(hŒJEXPORT_OP_CLOSE_BEFORE_UNLINK - always close cached files before unlinking”h]”hŒJEXPORT_OP_CLOSE_BEFORE_UNLINK - always close cached files before unlinking”…””}”(hj
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´K¶hj{
  ubj  )”}”(hhh]”hÝ)”}”(hX±  On some exportable filesystems (such as NFS) unlinking a file that
is still open can cause a fair bit of extra work. For instance,
the NFS client will do a "sillyrename" to ensure that the file
sticks around while it's still open. When reexporting, that open
file is held by nfsd so we usually end up doing a sillyrename, and
then immediately deleting the sillyrenamed file just afterward when
the link count actually goes to zero. Sometimes this delete can race
with other operations (for instance an rmdir of the parent directory).
This flag causes nfsd to close any open files for this inode _before_
calling into the vfs to do an unlink or a rename that would replace
an existing file.”h]”hX·  On some exportable filesystems (such as NFS) unlinking a file that
is still open can cause a fair bit of extra work. For instance,
the NFS client will do a â€œsillyrenameâ€ to ensure that the file
sticks around while itâ€™s still open. When reexporting, that open
file is held by nfsd so we usually end up doing a sillyrename, and
then immediately deleting the sillyrenamed file just afterward when
the link count actually goes to zero. Sometimes this delete can race
with other operations (for instance an rmdir of the parent directory).
This flag causes nfsd to close any open files for this inode _before_
calling into the vfs to do an unlink or a rename that would replace
an existing file.”…””}”(hj
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K¬hj
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj{
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´K¶hj
  ubjì  )”}”(hX@  EXPORT_OP_REMOTE_FS - Backing storage for this filesystem is remote
PF_LOCAL_THROTTLE exists for loopback NFSD, where a thread needs to
write to one bdi (the final bdi) in order to free up writes queued
to another bdi (the client bdi). Such threads get a private balance
of dirty pages so that dirty pages for the client bdi do not imact
the daemon writing to the final bdi. For filesystems whose durable
storage is not local (such as exported NFS filesystems), this
constraint has negative consequences. EXPORT_OP_REMOTE_FS enables
an export to disable writeback throttling.
”h]”(jò  )”}”(hŒCEXPORT_OP_REMOTE_FS - Backing storage for this filesystem is remote”h]”hŒCEXPORT_OP_REMOTE_FS - Backing storage for this filesystem is remote”…””}”(hj®
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´KÀhjª
  ubj  )”}”(hhh]”hÝ)”}”(hXû  PF_LOCAL_THROTTLE exists for loopback NFSD, where a thread needs to
write to one bdi (the final bdi) in order to free up writes queued
to another bdi (the client bdi). Such threads get a private balance
of dirty pages so that dirty pages for the client bdi do not imact
the daemon writing to the final bdi. For filesystems whose durable
storage is not local (such as exported NFS filesystems), this
constraint has negative consequences. EXPORT_OP_REMOTE_FS enables
an export to disable writeback throttling.”h]”hXû  PF_LOCAL_THROTTLE exists for loopback NFSD, where a thread needs to
write to one bdi (the final bdi) in order to free up writes queued
to another bdi (the client bdi). Such threads get a private balance
of dirty pages so that dirty pages for the client bdi do not imact
the daemon writing to the final bdi. For filesystems whose durable
storage is not local (such as exported NFS filesystems), this
constraint has negative consequences. EXPORT_OP_REMOTE_FS enables
an export to disable writeback throttling.”…””}”(hj¿
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K¹hj¼
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjª
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´KÀhj
  ubjì  )”}”(hX­  EXPORT_OP_NOATOMIC_ATTR - Filesystem does not update attributes atomically
EXPORT_OP_NOATOMIC_ATTR indicates that the exported filesystem
cannot provide the semantics required by the "atomic" boolean in
NFSv4's change_info4. This boolean indicates to a client whether the
returned before and after change attributes were obtained atomically
with the respect to the requested metadata operation (UNLINK,
OPEN/CREATE, MKDIR, etc).
”h]”(jò  )”}”(hŒJEXPORT_OP_NOATOMIC_ATTR - Filesystem does not update attributes atomically”h]”hŒJEXPORT_OP_NOATOMIC_ATTR - Filesystem does not update attributes atomically”…””}”(hjÝ
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´KÈhjÙ
  ubj  )”}”(hhh]”hÝ)”}”(hXa  EXPORT_OP_NOATOMIC_ATTR indicates that the exported filesystem
cannot provide the semantics required by the "atomic" boolean in
NFSv4's change_info4. This boolean indicates to a client whether the
returned before and after change attributes were obtained atomically
with the respect to the requested metadata operation (UNLINK,
OPEN/CREATE, MKDIR, etc).”h]”hXg  EXPORT_OP_NOATOMIC_ATTR indicates that the exported filesystem
cannot provide the semantics required by the â€œatomicâ€ boolean in
NFSv4â€™s change_info4. This boolean indicates to a client whether the
returned before and after change attributes were obtained atomically
with the respect to the requested metadata operation (UNLINK,
OPEN/CREATE, MKDIR, etc).”…””}”(hjî
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÃhjë
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjÙ
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´KÈhj
  ubjì  )”}”(hXÁ  EXPORT_OP_FLUSH_ON_CLOSE - Filesystem flushes file data on close(2)
On most filesystems, inodes can remain under writeback after the
file is closed. NFSD relies on client activity or local flusher
threads to handle writeback. Certain filesystems, such as NFS, flush
all of an inode's dirty data on last close. Exports that behave this
way should set EXPORT_OP_FLUSH_ON_CLOSE so that NFSD knows to skip
waiting for writeback when closing such files.
”h]”(jò  )”}”(hŒCEXPORT_OP_FLUSH_ON_CLOSE - Filesystem flushes file data on close(2)”h]”hŒCEXPORT_OP_FLUSH_ON_CLOSE - Filesystem flushes file data on close(2)”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´KÐhj  ubj  )”}”(hhh]”hÝ)”}”(hX|  On most filesystems, inodes can remain under writeback after the
file is closed. NFSD relies on client activity or local flusher
threads to handle writeback. Certain filesystems, such as NFS, flush
all of an inode's dirty data on last close. Exports that behave this
way should set EXPORT_OP_FLUSH_ON_CLOSE so that NFSD knows to skip
waiting for writeback when closing such files.”h]”hX~  On most filesystems, inodes can remain under writeback after the
file is closed. NFSD relies on client activity or local flusher
threads to handle writeback. Certain filesystems, such as NFS, flush
all of an inodeâ€™s dirty data on last close. Exports that behave this
way should set EXPORT_OP_FLUSH_ON_CLOSE so that NFSD knows to skip
waiting for writeback when closing such files.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KËhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´KÐhj
  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jæ  hj
  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jà  h³hÊh´Khj÷	  h²hubeh}”(h]”Œexport-operations-flags”ah ]”h"]”Œexport operations flags”ah$]”h&]”uh1hµhh·h²hh³hÊh´KŠubh¶)”}”(hhh]”(h»)”}”(hŒSigned Filehandles”h]”hŒSigned Filehandles”…””}”(hjN  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjK  h²hh³hÊh´KÓubhÝ)”}”(hŒ”To protect against filehandle guessing attacks, the Linux NFS server can be
configured to sign filehandles with a Message Authentication Code (MAC).”h]”hŒ”To protect against filehandle guessing attacks, the Linux NFS server can be
configured to sign filehandles with a Message Authentication Code (MAC).”…””}”(hj\  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÕhjK  h²hubhÝ)”}”(hX  Standard NFS filehandles are often predictable. If an attacker can guess
a valid filehandle for a file they do not have permission to access via
directory traversal, they may be able to bypass path-based permissions
(though they still remain subject to inode-level permissions).”h]”hX  Standard NFS filehandles are often predictable. If an attacker can guess
a valid filehandle for a file they do not have permission to access via
directory traversal, they may be able to bypass path-based permissions
(though they still remain subject to inode-level permissions).”…””}”(hjj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KØhjK  h²hubhÝ)”}”(hXa  Signed filehandles prevent this by appending a MAC to the filehandle
before it is sent to the client. Upon receiving a filehandle back from a
client, the server re-calculates the MAC using its internal key and
verifies it against the one provided. If the signatures do not match,
the server treats the filehandle as invalid (returning NFS[34]ERR_STALE).”h]”hXa  Signed filehandles prevent this by appending a MAC to the filehandle
before it is sent to the client. Upon receiving a filehandle back from a
client, the server re-calculates the MAC using its internal key and
verifies it against the one provided. If the signatures do not match,
the server treats the filehandle as invalid (returning NFS[34]ERR_STALE).”…””}”(hjx  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÝhjK  h²hubhÝ)”}”(hŒÁNote that signing filehandles provides integrity and authenticity but
not confidentiality. The contents of the filehandle remain visible to
the client; they simply cannot be forged or modified.”h]”hŒÁNote that signing filehandles provides integrity and authenticity but
not confidentiality. The contents of the filehandle remain visible to
the client; they simply cannot be forged or modified.”…””}”(hj†  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KãhjK  h²hubh¶)”}”(hhh]”(h»)”}”(hŒConfiguration”h]”hŒConfiguration”…””}”(hj—  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj”  h²hh³hÊh´KèubhÝ)”}”(hŒ€To enable signed filehandles, the administrator must provide a signing
key to the kernel and enable the "sign_fh" export option.”h]”hŒ„To enable signed filehandles, the administrator must provide a signing
key to the kernel and enable the â€œsign_fhâ€ export option.”…””}”(hj¥  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kêhj”  h²hubj>  )”}”(hhh]”(jC  )”}”(hŒ¯Providing a Key
The signing key is managed via the nfsd netlink interface. This key
is per-network-namespace and must be set before any exports using
"sign_fh" become active.
”h]”hÝ)”}”(hŒ®Providing a Key
The signing key is managed via the nfsd netlink interface. This key
is per-network-namespace and must be set before any exports using
"sign_fh" become active.”h]”hŒ²Providing a Key
The signing key is managed via the nfsd netlink interface. This key
is per-network-namespace and must be set before any exports using
â€œsign_fhâ€ become active.”…””}”(hjº  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kíhj¶  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj³  h²hh³hÊh´NubjC  )”}”(hŒÆExport Options
The feature is controlled on a per-export basis in /etc/exports:

sign_fh
  Enables signing for all filehandles generated under this export.

no_sign_fh
  (Default) Disables signing.
”h]”(hÝ)”}”(hŒOExport Options
The feature is controlled on a per-export basis in /etc/exports:”h]”hŒOExport Options
The feature is controlled on a per-export basis in /etc/exports:”…””}”(hjÒ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KòhjÎ  ubjç  )”}”(hhh]”(jì  )”}”(hŒIsign_fh
Enables signing for all filehandles generated under this export.
”h]”(jò  )”}”(hŒsign_fh”h]”hŒsign_fh”…””}”(hjç  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´Köhjã  ubj  )”}”(hhh]”hÝ)”}”(hŒ@Enables signing for all filehandles generated under this export.”h]”hŒ@Enables signing for all filehandles generated under this export.”…””}”(hjø  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Köhjõ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjã  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´Köhjà  ubjì  )”}”(hŒ'no_sign_fh
(Default) Disables signing.
”h]”(jò  )”}”(hŒ
no_sign_fh”h]”hŒ
no_sign_fh”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´Kùhj  ubj  )”}”(hhh]”hÝ)”}”(hŒ(Default) Disables signing.”h]”hŒ(Default) Disables signing.”…””}”(hj'  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kùhj$  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´Kùhjà  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jæ  hjÎ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jB  hj³  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”jz  j{  j|  hj}  j~  uh1j=  hj”  h²hh³hÊh´Kíubeh}”(h]”Œconfiguration”ah ]”h"]”Œconfiguration”ah$]”h&]”uh1hµhjK  h²hh³hÊh´Kèubh¶)”}”(hhh]”(h»)”}”(hŒKey Management and Rotation”h]”hŒKey Management and Rotation”…””}”(hj^  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj[  h²hh³hÊh´KüubhÝ)”}”(hŒQThe security of this mechanism relies entirely on the secrecy of the
signing key.”h]”hŒQThe security of this mechanism relies entirely on the secrecy of the
signing key.”…””}”(hjl  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kþhj[  h²hubjç  )”}”(hhh]”(jì  )”}”(hŒžInitial Setup:
The key should be generated using a high-quality random source and
loaded early in the boot process or during the nfs-server startup
sequence.
”h]”(jò  )”}”(hŒInitial Setup:”h]”hŒInitial Setup:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´Mhj}  ubj  )”}”(hhh]”hÝ)”}”(hŒŽThe key should be generated using a high-quality random source and
loaded early in the boot process or during the nfs-server startup
sequence.”h]”hŒŽThe key should be generated using a high-quality random source and
loaded early in the boot process or during the nfs-server startup
sequence.”…””}”(hj’  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj}  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´Mhjz  ubjì  )”}”(hŒÁChanging Keys:
If a key is changed while clients have active mounts, existing
filehandles held by those clients will become invalid, resulting in
"Stale file handle" errors on the client side.
”h]”(jò  )”}”(hŒChanging Keys:”h]”hŒChanging Keys:”…””}”(hj°  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´M	hj¬  ubj  )”}”(hhh]”hÝ)”}”(hŒ±If a key is changed while clients have active mounts, existing
filehandles held by those clients will become invalid, resulting in
"Stale file handle" errors on the client side.”h]”hŒµIf a key is changed while clients have active mounts, existing
filehandles held by those clients will become invalid, resulting in
â€œStale file handleâ€ errors on the client side.”…””}”(hjÁ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhj¾  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hj¬  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´M	hjz  h²hubjì  )”}”(hŒÍSafe Rotation:
Currently, there is no mechanism for "graceful" key rotation
(maintaining multiple valid keys). Changing the key is an atomic
operation that immediately invalidates all previous signatures.
”h]”(jò  )”}”(hŒSafe Rotation:”h]”hŒSafe Rotation:”…””}”(hjß  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jñ  h³hÊh´MhjÛ  ubj  )”}”(hhh]”hÝ)”}”(hŒ½Currently, there is no mechanism for "graceful" key rotation
(maintaining multiple valid keys). Changing the key is an atomic
operation that immediately invalidates all previous signatures.”h]”hŒÁCurrently, there is no mechanism for â€œgracefulâ€ key rotation
(maintaining multiple valid keys). Changing the key is an atomic
operation that immediately invalidates all previous signatures.”…””}”(hjð  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhjí  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j  hjÛ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jë  h³hÊh´Mhjz  h²hubeh}”(h]”h ]”h"]”h$]”h&]”uh1jæ  hj[  h²hh³hÊh´Nubeh}”(h]”Œkey-management-and-rotation”ah ]”h"]”Œkey management and rotation”ah$]”h&]”uh1hµhjK  h²hh³hÊh´Küubh¶)”}”(hhh]”(h»)”}”(hŒTransitioning Exports”h]”hŒTransitioning Exports”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj  h²hh³hÊh´MubhÝ)”}”(hŒmWhen adding or removing the "sign_fh" flag from an active export, the
following behaviors should be expected:”h]”hŒqWhen adding or removing the â€œsign_fhâ€ flag from an active export, the
following behaviors should be expected:”…””}”(hj)  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhj  h²hubhŒtable”“”)”}”(hhh]”hŒtgroup”“”)”}”(hhh]”(hŒcolspec”“”)”}”(hhh]”h}”(h]”h ]”h"]”h$]”h&]”Œcolwidth”Kuh1jA  hj>  ubjB  )”}”(hhh]”h}”(h]”h ]”h"]”h$]”h&]”Œcolwidth”K3uh1jA  hj>  ubhŒthead”“”)”}”(hhh]”hŒrow”“”)”}”(hhh]”(hŒentry”“”)”}”(hhh]”hÝ)”}”(hŒChange”h]”hŒChange”…””}”(hjf  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhjc  ubah}”(h]”h ]”h"]”h$]”h&]”uh1ja  hj^  ubjb  )”}”(hhh]”hÝ)”}”(hŒResult for Existing Clients”h]”hŒResult for Existing Clients”…””}”(hj}  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhjz  ubah}”(h]”h ]”h"]”h$]”h&]”uh1ja  hj^  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j\  hjY  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jW  hj>  ubhŒtbody”“”)”}”(hhh]”(j]  )”}”(hhh]”(jb  )”}”(hhh]”hÝ)”}”(hŒAdding sign_fh”h]”hŒAdding sign_fh”…””}”(hj¨  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhj¥  ubah}”(h]”h ]”h"]”h$]”h&]”uh1ja  hj¢  ubjb  )”}”(hhh]”hÝ)”}”(hŒdClients holding unsigned filehandles will find
them rejected, as the server now expects a
signature.”h]”hŒdClients holding unsigned filehandles will find
them rejected, as the server now expects a
signature.”…””}”(hj¿  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhj¼  ubah}”(h]”h ]”h"]”h$]”h&]”uh1ja  hj¢  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j\  hjŸ  ubj]  )”}”(hhh]”(jb  )”}”(hhh]”hÝ)”}”(hŒRemoving sign_fh”h]”hŒRemoving sign_fh”…””}”(hjß  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´MhjÜ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1ja  hjÙ  ubjb  )”}”(hhh]”hÝ)”}”(hŒ–Clients holding signed filehandles will find them
rejected, as the server now expects the
filehandle to end at its traditional boundary
without a MAC.”h]”hŒ–Clients holding signed filehandles will find them
rejected, as the server now expects the
filehandle to end at its traditional boundary
without a MAC.”…””}”(hjö  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhjó  ubah}”(h]”h ]”h"]”h$]”h&]”uh1ja  hjÙ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j\  hjŸ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j  hj>  ubeh}”(h]”h ]”h"]”h$]”h&]”Œcols”Kuh1j<  hj9  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j7  hj  h²hh³hÊh´NubhÝ)”}”(hŒÃBecause filehandles are often cached persistently by clients, adding or
removing this option should generally be done during a scheduled maintenance
window involving a NFS client unmount/remount.”h]”hŒÃBecause filehandles are often cached persistently by clients, adding or
removing this option should generally be done during a scheduled maintenance
window involving a NFS client unmount/remount.”…””}”(hj#  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´M#hj  h²hubeh}”(h]”Œtransitioning-exports”ah ]”h"]”Œtransitioning exports”ah$]”h&]”uh1hµhjK  h²hh³hÊh´Mubeh}”(h]”Œsigned-filehandles”ah ]”h"]”Œsigned filehandles”ah$]”h&]”uh1hµhh·h²hh³hÊh´KÓubeh}”(h]”Œmaking-filesystems-exportable”ah ]”h"]”Œmaking filesystems exportable”ah$]”h&]”uh1hµhhh²hh³hÊh´Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”hÊuh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(hºNŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”ja  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”jk  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”hÊŒ_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”}”(jF  jC  j  j
  j‰  j†  jô	  jñ	  jH  jE  j>  j;  jX  jU  j  j  j6  j3  uŒ	nametypes”}”(jF  ‰j  ‰j‰  ‰jô	  ‰jH  ‰j>  ‰jX  ‰j  ‰j6  ‰uh}”(jC  h·j
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