€•—Ã      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”Œ4/translations/zh_CN/filesystems/autofs-mount-control”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$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ4/translations/zh_TW/filesystems/autofs-mount-control”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ4/translations/it_IT/filesystems/autofs-mount-control”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ4/translations/ja_JP/filesystems/autofs-mount-control”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ4/translations/ko_KR/filesystems/autofs-mount-control”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ4/translations/sp_SP/filesystems/autofs-mount-control”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”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$]”h&]”Œ	xml:space”Œpreserve”uh1h¡hhhžhhŸŒN/var/lib/git/docbuild/linux/Documentation/filesystems/autofs-mount-control.rst”h KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒDMiscellaneous Device control operations for the autofs kernel module”h]”hŒDMiscellaneous Device control operations for the autofs kernel module”…””}”(hh»hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒThe problem”h]”hŒThe problem”…””}”(hhÌhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hhÉhžhhŸh³h KubhŒ	paragraph”“”)”}”(hŒpThere is a problem with active restarts in autofs (that is to say
restarting autofs when there are busy mounts).”h]”hŒpThere is a problem with active restarts in autofs (that is to say
restarting autofs when there are busy mounts).”…””}”(hhÜhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K
hhÉhžhubhÛ)”}”(hXm  During normal operation autofs uses a file descriptor opened on the
directory that is being managed in order to be able to issue control
operations. Using a file descriptor gives ioctl operations access to
autofs specific information stored in the super block. The operations
are things such as setting an autofs mount catatonic, setting the
expire timeout and requesting expire checks. As is explained below,
certain types of autofs triggered mounts can end up covering an autofs
mount itself which prevents us being able to use open(2) to obtain a
file descriptor for these operations if we don't already have one open.”h]”hXo  During normal operation autofs uses a file descriptor opened on the
directory that is being managed in order to be able to issue control
operations. Using a file descriptor gives ioctl operations access to
autofs specific information stored in the super block. The operations
are things such as setting an autofs mount catatonic, setting the
expire timeout and requesting expire checks. As is explained below,
certain types of autofs triggered mounts can end up covering an autofs
mount itself which prevents us being able to use open(2) to obtain a
file descriptor for these operations if we donâ€™t already have one open.”…””}”(hhêhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KhhÉhžhubhÛ)”}”(hXp  Currently autofs uses "umount -l" (lazy umount) to clear active mounts
at restart. While using lazy umount works for most cases, anything that
needs to walk back up the mount tree to construct a path, such as
getcwd(2) and the proc file system /proc/<pid>/cwd, no longer works
because the point from which the path is constructed has been detached
from the mount tree.”h]”hXt  Currently autofs uses â€œumount -lâ€ (lazy umount) to clear active mounts
at restart. While using lazy umount works for most cases, anything that
needs to walk back up the mount tree to construct a path, such as
getcwd(2) and the proc file system /proc/<pid>/cwd, no longer works
because the point from which the path is constructed has been detached
from the mount tree.”…””}”(hhøhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KhhÉhžhubhÛ)”}”(hX  The actual problem with autofs is that it can't reconnect to existing
mounts. Immediately one thinks of just adding the ability to remount
autofs file systems would solve it, but alas, that can't work. This is
because autofs direct mounts and the implementation of "on demand mount
and expire" of nested mount trees have the file system mounted directly
on top of the mount trigger directory dentry.”h]”hX—  The actual problem with autofs is that it canâ€™t reconnect to existing
mounts. Immediately one thinks of just adding the ability to remount
autofs file systems would solve it, but alas, that canâ€™t work. This is
because autofs direct mounts and the implementation of â€œon demand mount
and expireâ€ of nested mount trees have the file system mounted directly
on top of the mount trigger directory dentry.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KhhÉhžhubhÛ)”}”(hŒ»For example, there are two types of automount maps, direct (in the kernel
module source you will see a third type called an offset, which is just
a direct mount in disguise) and indirect.”h]”hŒ»For example, there are two types of automount maps, direct (in the kernel
module source you will see a third type called an offset, which is just
a direct mount in disguise) and indirect.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K%hhÉhžhubhÛ)”}”(hŒ;Here is a master map with direct and indirect map entries::”h]”hŒ:Here is a master map with direct and indirect map entries:”…””}”(hj"  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K)hhÉhžhubhŒliteral_block”“”)”}”(hŒ3/-      /etc/auto.direct
/test   /etc/auto.indirect”h]”hŒ3/-      /etc/auto.direct
/test   /etc/auto.indirect”…””}”hj2  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1j0  hŸh³h K+hhÉhžhubhÛ)”}”(hŒ!and the corresponding map files::”h]”hŒ and the corresponding map files:”…””}”(hj@  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K.hhÉhžhubj1  )”}”(hŒv/etc/auto.direct:

/automount/dparse/g6  budgie:/autofs/export1
/automount/dparse/g1  shark:/autofs/export1
and so on.”h]”hŒv/etc/auto.direct:

/automount/dparse/g6  budgie:/autofs/export1
/automount/dparse/g1  shark:/autofs/export1
and so on.”…””}”hjN  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1j0  hŸh³h K0hhÉhžhubhÛ)”}”(hŒ/etc/auto.indirect::”h]”hŒ/etc/auto.indirect:”…””}”(hj\  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K6hhÉhžhubj1  )”}”(hŒCg1    shark:/autofs/export1
g6    budgie:/autofs/export1
and so on.”h]”hŒCg1    shark:/autofs/export1
g6    budgie:/autofs/export1
and so on.”…””}”hjj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1j0  hŸh³h K8hhÉhžhubhÛ)”}”(hŒÜFor the above indirect map an autofs file system is mounted on /test and
mounts are triggered for each sub-directory key by the inode lookup
operation. So we see a mount of shark:/autofs/export1 on /test/g1, for
example.”h]”hŒÜFor the above indirect map an autofs file system is mounted on /test and
mounts are triggered for each sub-directory key by the inode lookup
operation. So we see a mount of shark:/autofs/export1 on /test/g1, for
example.”…””}”(hjx  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K<hhÉhžhubhÛ)”}”(hXR  The way that direct mounts are handled is by making an autofs mount on
each full path, such as /automount/dparse/g1, and using it as a mount
trigger. So when we walk on the path we mount shark:/autofs/export1 "on
top of this mount point". Since these are always directories we can
use the follow_link inode operation to trigger the mount.”h]”hXV  The way that direct mounts are handled is by making an autofs mount on
each full path, such as /automount/dparse/g1, and using it as a mount
trigger. So when we walk on the path we mount shark:/autofs/export1 â€œon
top of this mount pointâ€. Since these are always directories we can
use the follow_link inode operation to trigger the mount.”…””}”(hj†  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KAhhÉhžhubhÛ)”}”(hŒcBut, each entry in direct and indirect maps can have offsets (making
them multi-mount map entries).”h]”hŒcBut, each entry in direct and indirect maps can have offsets (making
them multi-mount map entries).”…””}”(hj”  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KGhhÉhžhubhÛ)”}”(hŒ8For example, an indirect mount map entry could also be::”h]”hŒ7For example, an indirect mount map entry could also be:”…””}”(hj¢  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KJhhÉhžhubj1  )”}”(hŒÔg1  \
/        shark:/autofs/export5/testing/test \
/s1      shark:/autofs/export/testing/test/s1 \
/s2      shark:/autofs/export5/testing/test/s2 \
/s1/ss1  shark:/autofs/export1 \
/s2/ss2  shark:/autofs/export2”h]”hŒÔg1  \
/        shark:/autofs/export5/testing/test \
/s1      shark:/autofs/export/testing/test/s1 \
/s2      shark:/autofs/export5/testing/test/s2 \
/s1/ss1  shark:/autofs/export1 \
/s2/ss2  shark:/autofs/export2”…””}”hj°  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1j0  hŸh³h KLhhÉhžhubhÛ)”}”(hŒ8and a similarly a direct mount map entry could also be::”h]”hŒ7and a similarly a direct mount map entry could also be:”…””}”(hj¾  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KShhÉhžhubj1  )”}”(hŒô/automount/dparse/g1 \
    /       shark:/autofs/export5/testing/test \
    /s1     shark:/autofs/export/testing/test/s1 \
    /s2     shark:/autofs/export5/testing/test/s2 \
    /s1/ss1 shark:/autofs/export2 \
    /s2/ss2 shark:/autofs/export2”h]”hŒô/automount/dparse/g1 \
    /       shark:/autofs/export5/testing/test \
    /s1     shark:/autofs/export/testing/test/s1 \
    /s2     shark:/autofs/export5/testing/test/s2 \
    /s1/ss1 shark:/autofs/export2 \
    /s2/ss2 shark:/autofs/export2”…””}”hjÌ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1j0  hŸh³h KUhhÉhžhubhÛ)”}”(hXå  One of the issues with version 4 of autofs was that, when mounting an
entry with a large number of offsets, possibly with nesting, we needed
to mount and umount all of the offsets as a single unit. Not really a
problem, except for people with a large number of offsets in map entries.
This mechanism is used for the well known "hosts" map and we have seen
cases (in 2.4) where the available number of mounts are exhausted or
where the number of privileged ports available is exhausted.”h]”hXé  One of the issues with version 4 of autofs was that, when mounting an
entry with a large number of offsets, possibly with nesting, we needed
to mount and umount all of the offsets as a single unit. Not really a
problem, except for people with a large number of offsets in map entries.
This mechanism is used for the well known â€œhostsâ€ map and we have seen
cases (in 2.4) where the available number of mounts are exhausted or
where the number of privileged ports available is exhausted.”…””}”(hjÚ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K\hhÉhžhubhÛ)”}”(hX•  In version 5 we mount only as we go down the tree of offsets and
similarly for expiring them which resolves the above problem. There is
somewhat more detail to the implementation but it isn't needed for the
sake of the problem explanation. The one important detail is that these
offsets are implemented using the same mechanism as the direct mounts
above and so the mount points can be covered by a mount.”h]”hX—  In version 5 we mount only as we go down the tree of offsets and
similarly for expiring them which resolves the above problem. There is
somewhat more detail to the implementation but it isnâ€™t needed for the
sake of the problem explanation. The one important detail is that these
offsets are implemented using the same mechanism as the direct mounts
above and so the mount points can be covered by a mount.”…””}”(hjè  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KdhhÉhžhubhÛ)”}”(hXe  The current autofs implementation uses an ioctl file descriptor opened
on the mount point for control operations. The references held by the
descriptor are accounted for in checks made to determine if a mount is
in use and is also used to access autofs file system information held
in the mount super block. So the use of a file handle needs to be
retained.”h]”hXe  The current autofs implementation uses an ioctl file descriptor opened
on the mount point for control operations. The references held by the
descriptor are accounted for in checks made to determine if a mount is
in use and is also used to access autofs file system information held
in the mount super block. So the use of a file handle needs to be
retained.”…””}”(hjö  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KkhhÉhžhubeh}”(h]”Œthe-problem”ah ]”h"]”Œthe problem”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒThe Solution”h]”hŒThe Solution”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj  hžhhŸh³h KtubhÛ)”}”(hXZ  To be able to restart autofs leaving existing direct, indirect and
offset mounts in place we need to be able to obtain a file handle
for these potentially covered autofs mount points. Rather than just
implement an isolated operation it was decided to re-implement the
existing ioctl interface and add new operations to provide this
functionality.”h]”hXZ  To be able to restart autofs leaving existing direct, indirect and
offset mounts in place we need to be able to obtain a file handle
for these potentially covered autofs mount points. Rather than just
implement an isolated operation it was decided to re-implement the
existing ioctl interface and add new operations to provide this
functionality.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Kvhj  hžhubhÛ)”}”(hX=  In addition, to be able to reconstruct a mount tree that has busy mounts,
the uid and gid of the last user that triggered the mount needs to be
available because these can be used as macro substitution variables in
autofs maps. They are recorded at mount request time and an operation
has been added to retrieve them.”h]”hX=  In addition, to be able to reconstruct a mount tree that has busy mounts,
the uid and gid of the last user that triggered the mount needs to be
available because these can be used as macro substitution variables in
autofs maps. They are recorded at mount request time and an operation
has been added to retrieve them.”…””}”(hj+  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K}hj  hžhubhÛ)”}”(hX  Since we're re-implementing the control interface, a couple of other
problems with the existing interface have been addressed. First, when
a mount or expire operation completes a status is returned to the
kernel by either a "send ready" or a "send fail" operation. The
"send fail" operation of the ioctl interface could only ever send
ENOENT so the re-implementation allows user space to send an actual
status. Another expensive operation in user space, for those using
very large maps, is discovering if a mount is present. Usually this
involves scanning /proc/mounts and since it needs to be done quite
often it can introduce significant overhead when there are many entries
in the mount table. An operation to lookup the mount status of a mount
point dentry (covered or not) has also been added.”h]”hX,  Since weâ€™re re-implementing the control interface, a couple of other
problems with the existing interface have been addressed. First, when
a mount or expire operation completes a status is returned to the
kernel by either a â€œsend readyâ€ or a â€œsend failâ€ operation. The
â€œsend failâ€ operation of the ioctl interface could only ever send
ENOENT so the re-implementation allows user space to send an actual
status. Another expensive operation in user space, for those using
very large maps, is discovering if a mount is present. Usually this
involves scanning /proc/mounts and since it needs to be done quite
often it can introduce significant overhead when there are many entries
in the mount table. An operation to lookup the mount status of a mount
point dentry (covered or not) has also been added.”…””}”(hj9  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Kƒhj  hžhubhÛ)”}”(hXÿ  Current kernel development policy recommends avoiding the use of the
ioctl mechanism in favor of systems such as Netlink. An implementation
using this system was attempted to evaluate its suitability and it was
found to be inadequate, in this case. The Generic Netlink system was
used for this as raw Netlink would lead to a significant increase in
complexity. There's no question that the Generic Netlink system is an
elegant solution for common case ioctl functions but it's not a complete
replacement probably because its primary purpose in life is to be a
message bus implementation rather than specifically an ioctl replacement.
While it would be possible to work around this there is one concern
that lead to the decision to not use it. This is that the autofs
expire in the daemon has become far to complex because umount
candidates are enumerated, almost for no other reason than to "count"
the number of times to call the expire ioctl. This involves scanning
the mount table which has proved to be a big overhead for users with
large maps. The best way to improve this is try and get back to the
way the expire was done long ago. That is, when an expire request is
issued for a mount (file handle) we should continually call back to
the daemon until we can't umount any more mounts, then return the
appropriate status to the daemon. At the moment we just expire one
mount at a time. A Generic Netlink implementation would exclude this
possibility for future development due to the requirements of the
message bus architecture.”h]”hX	  Current kernel development policy recommends avoiding the use of the
ioctl mechanism in favor of systems such as Netlink. An implementation
using this system was attempted to evaluate its suitability and it was
found to be inadequate, in this case. The Generic Netlink system was
used for this as raw Netlink would lead to a significant increase in
complexity. Thereâ€™s no question that the Generic Netlink system is an
elegant solution for common case ioctl functions but itâ€™s not a complete
replacement probably because its primary purpose in life is to be a
message bus implementation rather than specifically an ioctl replacement.
While it would be possible to work around this there is one concern
that lead to the decision to not use it. This is that the autofs
expire in the daemon has become far to complex because umount
candidates are enumerated, almost for no other reason than to â€œcountâ€
the number of times to call the expire ioctl. This involves scanning
the mount table which has proved to be a big overhead for users with
large maps. The best way to improve this is try and get back to the
way the expire was done long ago. That is, when an expire request is
issued for a mount (file handle) we should continually call back to
the daemon until we canâ€™t umount any more mounts, then return the
appropriate status to the daemon. At the moment we just expire one
mount at a time. A Generic Netlink implementation would exclude this
possibility for future development due to the requirements of the
message bus architecture.”…””}”(hjG  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Khj  hžhubeh}”(h]”Œthe-solution”ah ]”h"]”Œthe solution”ah$]”h&]”uh1h´hh¶hžhhŸh³h Ktubhµ)”}”(hhh]”(hº)”}”(hŒ3autofs Miscellaneous Device mount control interface”h]”hŒ3autofs Miscellaneous Device mount control interface”…””}”(hj`  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj]  hžhhŸh³h KªubhÛ)”}”(hŒFThe control interface is opening a device node, typically /dev/autofs.”h]”hŒFThe control interface is opening a device node, typically /dev/autofs.”…””}”(hjn  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K¬hj]  hžhubhÛ)”}”(hŒmAll the ioctls use a common structure to pass the needed parameter
information and return operation results::”h]”hŒlAll the ioctls use a common structure to pass the needed parameter
information and return operation results:”…””}”(hj|  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h K®hj]  hžhubj1  )”}”(hXÚ  struct autofs_dev_ioctl {
        __u32 ver_major;
        __u32 ver_minor;
        __u32 size;             /* total size of data passed in
                                * including this struct */
        __s32 ioctlfd;          /* automount command fd */

        /* Command parameters */
        union {
                struct args_protover                protover;
                struct args_protosubver             protosubver;
                struct args_openmount               openmount;
                struct args_ready           ready;
                struct args_fail            fail;
                struct args_setpipefd               setpipefd;
                struct args_timeout         timeout;
                struct args_requester               requester;
                struct args_expire          expire;
                struct args_askumount               askumount;
                struct args_ismountpoint    ismountpoint;
        };

        char path[];
};”h]”hXÚ  struct autofs_dev_ioctl {
        __u32 ver_major;
        __u32 ver_minor;
        __u32 size;             /* total size of data passed in
                                * including this struct */
        __s32 ioctlfd;          /* automount command fd */

        /* Command parameters */
        union {
                struct args_protover                protover;
                struct args_protosubver             protosubver;
                struct args_openmount               openmount;
                struct args_ready           ready;
                struct args_fail            fail;
                struct args_setpipefd               setpipefd;
                struct args_timeout         timeout;
                struct args_requester               requester;
                struct args_expire          expire;
                struct args_askumount               askumount;
                struct args_ismountpoint    ismountpoint;
        };

        char path[];
};”…””}”hjŠ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1j0  hŸh³h K±hj]  hžhubhÛ)”}”(hX   The ioctlfd field is a mount point file descriptor of an autofs mount
point. It is returned by the open call and is used by all calls except
the check for whether a given path is a mount point, where it may
optionally be used to check a specific mount corresponding to a given
mount point file descriptor, and when requesting the uid and gid of the
last successful mount on a directory within the autofs file system.”h]”hX   The ioctlfd field is a mount point file descriptor of an autofs mount
point. It is returned by the open call and is used by all calls except
the check for whether a given path is a mount point, where it may
optionally be used to check a specific mount corresponding to a given
mount point file descriptor, and when requesting the uid and gid of the
last successful mount on a directory within the autofs file system.”…””}”(hj˜  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KÊhj]  hžhubhÛ)”}”(hŒYThe union is used to communicate parameters and results of calls made
as described below.”h]”hŒYThe union is used to communicate parameters and results of calls made
as described below.”…””}”(hj¦  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KÑhj]  hžhubhÛ)”}”(hŒ³The path field is used to pass a path where it is needed and the size field
is used account for the increased structure length when translating the
structure sent from user space.”h]”hŒ³The path field is used to pass a path where it is needed and the size field
is used account for the increased structure length when translating the
structure sent from user space.”…””}”(hj´  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KÔhj]  hžhubhÛ)”}”(hŒ–This structure can be initialized before setting specific fields by using
the void function call init_autofs_dev_ioctl(``struct autofs_dev_ioctl *``).”h]”(hŒwThis structure can be initialized before setting specific fields by using
the void function call init_autofs_dev_ioctl(”…””}”(hjÂ  hžhhŸNh NubhŒliteral”“”)”}”(hŒ``struct autofs_dev_ioctl *``”h]”hŒstruct autofs_dev_ioctl *”…””}”(hjÌ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÊ  hjÂ  ubhŒ).”…””}”(hjÂ  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KØhj]  hžhubhÛ)”}”(hXœ  All of the ioctls perform a copy of this structure from user space to
kernel space and return -EINVAL if the size parameter is smaller than
the structure size itself, -ENOMEM if the kernel memory allocation fails
or -EFAULT if the copy itself fails. Other checks include a version check
of the compiled in user space version against the module version and a
mismatch results in a -EINVAL return. If the size field is greater than
the structure size then a path is assumed to be present and is checked to
ensure it begins with a "/" and is NULL terminated, otherwise -EINVAL is
returned. Following these checks, for all ioctl commands except
AUTOFS_DEV_IOCTL_VERSION_CMD, AUTOFS_DEV_IOCTL_OPENMOUNT_CMD and
AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD the ioctlfd is validated and if it is
not a valid descriptor or doesn't correspond to an autofs mount point
an error of -EBADF, -ENOTTY or -EINVAL (not an autofs descriptor) is
returned.”h]”hX¢  All of the ioctls perform a copy of this structure from user space to
kernel space and return -EINVAL if the size parameter is smaller than
the structure size itself, -ENOMEM if the kernel memory allocation fails
or -EFAULT if the copy itself fails. Other checks include a version check
of the compiled in user space version against the module version and a
mismatch results in a -EINVAL return. If the size field is greater than
the structure size then a path is assumed to be present and is checked to
ensure it begins with a â€œ/â€ and is NULL terminated, otherwise -EINVAL is
returned. Following these checks, for all ioctl commands except
AUTOFS_DEV_IOCTL_VERSION_CMD, AUTOFS_DEV_IOCTL_OPENMOUNT_CMD and
AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD the ioctlfd is validated and if it is
not a valid descriptor or doesnâ€™t correspond to an autofs mount point
an error of -EBADF, -ENOTTY or -EINVAL (not an autofs descriptor) is
returned.”…””}”(hjä  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h KÛhj]  hžhubeh}”(h]”Œ3autofs-miscellaneous-device-mount-control-interface”ah ]”h"]”Œ3autofs miscellaneous device mount control interface”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kªubhµ)”}”(hhh]”(hº)”}”(hŒ
The ioctls”h]”hŒ
The ioctls”…””}”(hjý  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjú  hžhhŸh³h KìubhÛ)”}”(hŒíAn example of an implementation which uses this interface can be seen
in autofs version 5.0.4 and later in file lib/dev-ioctl-lib.c of the
distribution tar available for download from kernel.org in directory
/pub/linux/daemons/autofs/v5.”h]”hŒíAn example of an implementation which uses this interface can be seen
in autofs version 5.0.4 and later in file lib/dev-ioctl-lib.c of the
distribution tar available for download from kernel.org in directory
/pub/linux/daemons/autofs/v5.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Kîhjú  hžhubhÛ)”}”(hŒCThe device node ioctl operations implemented by this interface are:”h]”hŒCThe device node ioctl operations implemented by this interface are:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Kóhjú  hžhubhµ)”}”(hhh]”(hº)”}”(hŒAUTOFS_DEV_IOCTL_VERSION”h]”hŒAUTOFS_DEV_IOCTL_VERSION”…””}”(hj*  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj'  hžhhŸh³h K÷ubhÛ)”}”(hX.  Get the major and minor version of the autofs device ioctl kernel module
implementation. It requires an initialized struct autofs_dev_ioctl as an
input parameter and sets the version information in the passed in structure.
It returns 0 on success or the error -EINVAL if a version mismatch is
detected.”h]”hX.  Get the major and minor version of the autofs device ioctl kernel module
implementation. It requires an initialized struct autofs_dev_ioctl as an
input parameter and sets the version information in the passed in structure.
It returns 0 on success or the error -EINVAL if a version mismatch is
detected.”…””}”(hj8  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Kùhj'  hžhubeh}”(h]”Œautofs-dev-ioctl-version”ah ]”h"]”Œautofs_dev_ioctl_version”ah$]”h&]”uh1h´hjú  hžhhŸh³h K÷ubhµ)”}”(hhh]”(hº)”}”(hŒBAUTOFS_DEV_IOCTL_PROTOVER_CMD and AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD”h]”hŒBAUTOFS_DEV_IOCTL_PROTOVER_CMD and AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD”…””}”(hjQ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjN  hžhhŸh³h MubhÛ)”}”(hX´  Get the major and minor version of the autofs protocol version understood
by loaded module. This call requires an initialized struct autofs_dev_ioctl
with the ioctlfd field set to a valid autofs mount point descriptor
and sets the requested version number in version field of struct args_protover
or sub_version field of struct args_protosubver. These commands return
0 on success or one of the negative error codes if validation fails.”h]”hX´  Get the major and minor version of the autofs protocol version understood
by loaded module. This call requires an initialized struct autofs_dev_ioctl
with the ioctlfd field set to a valid autofs mount point descriptor
and sets the requested version number in version field of struct args_protover
or sub_version field of struct args_protosubver. These commands return
0 on success or one of the negative error codes if validation fails.”…””}”(hj_  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h MhjN  hžhubeh}”(h]”ŒBautofs-dev-ioctl-protover-cmd-and-autofs-dev-ioctl-protosubver-cmd”ah ]”h"]”ŒBautofs_dev_ioctl_protover_cmd and autofs_dev_ioctl_protosubver_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h Mubhµ)”}”(hhh]”(hº)”}”(hŒ:AUTOFS_DEV_IOCTL_OPENMOUNT and AUTOFS_DEV_IOCTL_CLOSEMOUNT”h]”hŒ:AUTOFS_DEV_IOCTL_OPENMOUNT and AUTOFS_DEV_IOCTL_CLOSEMOUNT”…””}”(hjx  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hju  hžhhŸh³h MubhÛ)”}”(hX  Obtain and release a file descriptor for an autofs managed mount point
path. The open call requires an initialized struct autofs_dev_ioctl with
the path field set and the size field adjusted appropriately as well
as the devid field of struct args_openmount set to the device number of
the autofs mount. The device number can be obtained from the mount options
shown in /proc/mounts. The close call requires an initialized struct
autofs_dev_ioct with the ioctlfd field set to the descriptor obtained
from the open call. The release of the file descriptor can also be done
with close(2) so any open descriptors will also be closed at process exit.
The close call is included in the implemented operations largely for
completeness and to provide for a consistent user space implementation.”h]”hX  Obtain and release a file descriptor for an autofs managed mount point
path. The open call requires an initialized struct autofs_dev_ioctl with
the path field set and the size field adjusted appropriately as well
as the devid field of struct args_openmount set to the device number of
the autofs mount. The device number can be obtained from the mount options
shown in /proc/mounts. The close call requires an initialized struct
autofs_dev_ioct with the ioctlfd field set to the descriptor obtained
from the open call. The release of the file descriptor can also be done
with close(2) so any open descriptors will also be closed at process exit.
The close call is included in the implemented operations largely for
completeness and to provide for a consistent user space implementation.”…””}”(hj†  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Mhju  hžhubeh}”(h]”Œ:autofs-dev-ioctl-openmount-and-autofs-dev-ioctl-closemount”ah ]”h"]”Œ:autofs_dev_ioctl_openmount and autofs_dev_ioctl_closemount”ah$]”h&]”uh1h´hjú  hžhhŸh³h Mubhµ)”}”(hhh]”(hº)”}”(hŒ8AUTOFS_DEV_IOCTL_READY_CMD and AUTOFS_DEV_IOCTL_FAIL_CMD”h]”hŒ8AUTOFS_DEV_IOCTL_READY_CMD and AUTOFS_DEV_IOCTL_FAIL_CMD”…””}”(hjŸ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjœ  hžhhŸh³h MubhÛ)”}”(hXØ  Return mount and expire result status from user space to the kernel.
Both of these calls require an initialized struct autofs_dev_ioctl
with the ioctlfd field set to the descriptor obtained from the open
call and the token field of struct args_ready or struct args_fail set
to the wait queue token number, received by user space in the foregoing
mount or expire request. The status field of struct args_fail is set to
the errno of the operation. It is set to 0 on success.”h]”hXØ  Return mount and expire result status from user space to the kernel.
Both of these calls require an initialized struct autofs_dev_ioctl
with the ioctlfd field set to the descriptor obtained from the open
call and the token field of struct args_ready or struct args_fail set
to the wait queue token number, received by user space in the foregoing
mount or expire request. The status field of struct args_fail is set to
the errno of the operation. It is set to 0 on success.”…””}”(hj­  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Mhjœ  hžhubeh}”(h]”Œ8autofs-dev-ioctl-ready-cmd-and-autofs-dev-ioctl-fail-cmd”ah ]”h"]”Œ8autofs_dev_ioctl_ready_cmd and autofs_dev_ioctl_fail_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h Mubhµ)”}”(hhh]”(hº)”}”(hŒAUTOFS_DEV_IOCTL_SETPIPEFD_CMD”h]”hŒAUTOFS_DEV_IOCTL_SETPIPEFD_CMD”…””}”(hjÆ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjÃ  hžhhŸh³h M(ubhÛ)”}”(hXˆ  Set the pipe file descriptor used for kernel communication to the daemon.
Normally this is set at mount time using an option but when reconnecting
to a existing mount we need to use this to tell the autofs mount about
the new kernel pipe descriptor. In order to protect mounts against
incorrectly setting the pipe descriptor we also require that the autofs
mount be catatonic (see next call).”h]”hXˆ  Set the pipe file descriptor used for kernel communication to the daemon.
Normally this is set at mount time using an option but when reconnecting
to a existing mount we need to use this to tell the autofs mount about
the new kernel pipe descriptor. In order to protect mounts against
incorrectly setting the pipe descriptor we also require that the autofs
mount be catatonic (see next call).”…””}”(hjÔ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h M*hjÃ  hžhubhÛ)”}”(hXs  The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call and
the pipefd field of struct args_setpipefd set to descriptor of the pipe.
On success the call also sets the process group id used to identify the
controlling process (eg. the owning automount(8) daemon) to the process
group of the caller.”h]”hXs  The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call and
the pipefd field of struct args_setpipefd set to descriptor of the pipe.
On success the call also sets the process group id used to identify the
controlling process (eg. the owning automount(8) daemon) to the process
group of the caller.”…””}”(hjâ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h M1hjÃ  hžhubeh}”(h]”Œautofs-dev-ioctl-setpipefd-cmd”ah ]”h"]”Œautofs_dev_ioctl_setpipefd_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h M(ubhµ)”}”(hhh]”(hº)”}”(hŒAUTOFS_DEV_IOCTL_CATATONIC_CMD”h]”hŒAUTOFS_DEV_IOCTL_CATATONIC_CMD”…””}”(hjû  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjø  hžhhŸh³h M:ubhÛ)”}”(hŒÀMake the autofs mount point catatonic. The autofs mount will no longer
issue mount requests, the kernel communication pipe descriptor is released
and any remaining waits in the queue released.”h]”hŒÀMake the autofs mount point catatonic. The autofs mount will no longer
issue mount requests, the kernel communication pipe descriptor is released
and any remaining waits in the queue released.”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h M<hjø  hžhubhÛ)”}”(hŒ‚The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call.”h]”hŒ‚The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h M@hjø  hžhubeh}”(h]”Œautofs-dev-ioctl-catatonic-cmd”ah ]”h"]”Œautofs_dev_ioctl_catatonic_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h M:ubhµ)”}”(hhh]”(hº)”}”(hŒAUTOFS_DEV_IOCTL_TIMEOUT_CMD”h]”hŒAUTOFS_DEV_IOCTL_TIMEOUT_CMD”…””}”(hj0  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj-  hžhhŸh³h MEubhÛ)”}”(hŒ?Set the expire timeout for mounts within an autofs mount point.”h]”hŒ?Set the expire timeout for mounts within an autofs mount point.”…””}”(hj>  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h MGhj-  hžhubhÛ)”}”(hŒ‚The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call.”h]”hŒ‚The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call.”…””}”(hjL  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h MIhj-  hžhubeh}”(h]”Œautofs-dev-ioctl-timeout-cmd”ah ]”h"]”Œautofs_dev_ioctl_timeout_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h MEubhµ)”}”(hhh]”(hº)”}”(hŒAUTOFS_DEV_IOCTL_REQUESTER_CMD”h]”hŒAUTOFS_DEV_IOCTL_REQUESTER_CMD”…””}”(hje  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjb  hžhhŸh³h MNubhÛ)”}”(hŒhReturn the uid and gid of the last process to successfully trigger a the
mount on the given path dentry.”h]”hŒhReturn the uid and gid of the last process to successfully trigger a the
mount on the given path dentry.”…””}”(hjs  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h MPhjb  hžhubhÛ)”}”(hŒõThe call requires an initialized struct autofs_dev_ioctl with the path
field set to the mount point in question and the size field adjusted
appropriately. Upon return the uid field of struct args_requester contains
the uid and gid field the gid.”h]”hŒõThe call requires an initialized struct autofs_dev_ioctl with the path
field set to the mount point in question and the size field adjusted
appropriately. Upon return the uid field of struct args_requester contains
the uid and gid field the gid.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h MShjb  hžhubhÛ)”}”(hXM  When reconstructing an autofs mount tree with active mounts we need to
re-connect to mounts that may have used the original process uid and
gid (or string variations of them) for mount lookups within the map entry.
This call provides the ability to obtain this uid and gid so they may be
used by user space for the mount map lookups.”h]”hXM  When reconstructing an autofs mount tree with active mounts we need to
re-connect to mounts that may have used the original process uid and
gid (or string variations of them) for mount lookups within the map entry.
This call provides the ability to obtain this uid and gid so they may be
used by user space for the mount map lookups.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h MXhjb  hžhubeh}”(h]”Œautofs-dev-ioctl-requester-cmd”ah ]”h"]”Œautofs_dev_ioctl_requester_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h MNubhµ)”}”(hhh]”(hº)”}”(hŒAUTOFS_DEV_IOCTL_EXPIRE_CMD”h]”hŒAUTOFS_DEV_IOCTL_EXPIRE_CMD”…””}”(hj¨  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj¥  hžhhŸh³h M`ubhÛ)”}”(hŒ‡Issue an expire request to the kernel for an autofs mount. Typically
this ioctl is called until no further expire candidates are found.”h]”hŒ‡Issue an expire request to the kernel for an autofs mount. Typically
this ioctl is called until no further expire candidates are found.”…””}”(hj¶  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Mbhj¥  hžhubhÛ)”}”(hXá  The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call. In
addition an immediate expire that's independent of the mount timeout,
and a forced expire that's independent of whether the mount is busy,
can be requested by setting the how field of struct args_expire to
AUTOFS_EXP_IMMEDIATE or AUTOFS_EXP_FORCED, respectively . If no
expire candidates can be found the ioctl returns -1 with errno set to
EAGAIN.”h]”hXå  The call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call. In
addition an immediate expire thatâ€™s independent of the mount timeout,
and a forced expire thatâ€™s independent of whether the mount is busy,
can be requested by setting the how field of struct args_expire to
AUTOFS_EXP_IMMEDIATE or AUTOFS_EXP_FORCED, respectively . If no
expire candidates can be found the ioctl returns -1 with errno set to
EAGAIN.”…””}”(hjÄ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Mehj¥  hžhubhÛ)”}”(hŒ¾This call causes the kernel module to check the mount corresponding
to the given ioctlfd for mounts that can be expired, issues an expire
request back to the daemon and waits for completion.”h]”hŒ¾This call causes the kernel module to check the mount corresponding
to the given ioctlfd for mounts that can be expired, issues an expire
request back to the daemon and waits for completion.”…””}”(hjÒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Mnhj¥  hžhubeh}”(h]”Œautofs-dev-ioctl-expire-cmd”ah ]”h"]”Œautofs_dev_ioctl_expire_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h M`ubhµ)”}”(hhh]”(hº)”}”(hŒAUTOFS_DEV_IOCTL_ASKUMOUNT_CMD”h]”hŒAUTOFS_DEV_IOCTL_ASKUMOUNT_CMD”…””}”(hjë  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjè  hžhhŸh³h MsubhÛ)”}”(hŒ*Checks if an autofs mount point is in use.”h]”hŒ*Checks if an autofs mount point is in use.”…””}”(hjù  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Muhjè  hžhubhÛ)”}”(hŒéThe call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call and
it returns the result in the may_umount field of struct args_askumount,
1 for busy and 0 otherwise.”h]”hŒéThe call requires an initialized struct autofs_dev_ioctl with the
ioctlfd field set to the descriptor obtained from the open call and
it returns the result in the may_umount field of struct args_askumount,
1 for busy and 0 otherwise.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Mwhjè  hžhubeh}”(h]”Œautofs-dev-ioctl-askumount-cmd”ah ]”h"]”Œautofs_dev_ioctl_askumount_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h Msubhµ)”}”(hhh]”(hº)”}”(hŒ!AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD”h]”hŒ!AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD”…””}”(hj   hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj  hžhhŸh³h M~ubhÛ)”}”(hŒ(Check if the given path is a mountpoint.”h]”hŒ(Check if the given path is a mountpoint.”…””}”(hj.  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h M€hj  hžhubhÛ)”}”(hXÇ  The call requires an initialized struct autofs_dev_ioctl. There are two
possible variations. Both use the path field set to the path of the mount
point to check and the size field adjusted appropriately. One uses the
ioctlfd field to identify a specific mount point to check while the other
variation uses the path and optionally in.type field of struct args_ismountpoint
set to an autofs mount type. The call returns 1 if this is a mount point
and sets out.devid field to the device number of the mount and out.magic
field to the relevant super block magic number (described below) or 0 if
it isn't a mountpoint. In both cases the device number (as returned
by new_encode_dev()) is returned in out.devid field.”h]”hXÉ  The call requires an initialized struct autofs_dev_ioctl. There are two
possible variations. Both use the path field set to the path of the mount
point to check and the size field adjusted appropriately. One uses the
ioctlfd field to identify a specific mount point to check while the other
variation uses the path and optionally in.type field of struct args_ismountpoint
set to an autofs mount type. The call returns 1 if this is a mount point
and sets out.devid field to the device number of the mount and out.magic
field to the relevant super block magic number (described below) or 0 if
it isnâ€™t a mountpoint. In both cases the device number (as returned
by new_encode_dev()) is returned in out.devid field.”…””}”(hj<  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h M‚hj  hžhubhÛ)”}”(hXÒ  If supplied with a file descriptor we're looking for a specific mount,
not necessarily at the top of the mounted stack. In this case the path
the descriptor corresponds to is considered a mountpoint if it is itself
a mountpoint or contains a mount, such as a multi-mount without a root
mount. In this case we return 1 if the descriptor corresponds to a mount
point and also returns the super magic of the covering mount if there
is one or 0 if it isn't a mountpoint.”h]”hXÖ  If supplied with a file descriptor weâ€™re looking for a specific mount,
not necessarily at the top of the mounted stack. In this case the path
the descriptor corresponds to is considered a mountpoint if it is itself
a mountpoint or contains a mount, such as a multi-mount without a root
mount. In this case we return 1 if the descriptor corresponds to a mount
point and also returns the super magic of the covering mount if there
is one or 0 if it isnâ€™t a mountpoint.”…””}”(hjJ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h Mhj  hžhubhÛ)”}”(hXn  If a path is supplied (and the ioctlfd field is set to -1) then the path
is looked up and is checked to see if it is the root of a mount. If a
type is also given we are looking for a particular autofs mount and if
a match isn't found a fail is returned. If the located path is the
root of a mount 1 is returned along with the super magic of the mount
or 0 otherwise.”h]”hXp  If a path is supplied (and the ioctlfd field is set to -1) then the path
is looked up and is checked to see if it is the root of a mount. If a
type is also given we are looking for a particular autofs mount and if
a match isnâ€™t found a fail is returned. If the located path is the
root of a mount 1 is returned along with the super magic of the mount
or 0 otherwise.”…””}”(hjX  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÚhŸh³h M•hj  hžhubeh}”(h]”Œ!autofs-dev-ioctl-ismountpoint-cmd”ah ]”h"]”Œ!autofs_dev_ioctl_ismountpoint_cmd”ah$]”h&]”uh1h´hjú  hžhhŸh³h M~ubeh}”(h]”Œ
the-ioctls”ah ]”h"]”Œ
the ioctls”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kìubeh}”(h]”ŒDmiscellaneous-device-control-operations-for-the-autofs-kernel-module”ah ]”h"]”ŒDmiscellaneous device control operations for the autofs kernel module”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
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id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
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