Revert "fanotify: remove unneeded sub-zero check for unsigned value"

This reverts commit e6595224464b692ddae193d783402130d1625147.

These kinds of patches are only making the code worse.

Compilers

Revert "fanotify: remove unneeded sub-zero check for unsigned value"

This reverts commit e6595224464b692ddae193d783402130d1625147.

These kinds of patches are only making the code worse.

Compilers don't care about the unnecessary check, but removing it makes
the code less obvious to a human. The declaration of 'len' is more than
80 lines earlier, so a human won't easily see that 'len' is of an
unsigned type, so to a human the range check that checks against zero is
much more explicit and obvious.

Any tool that complains about a range check like this just because the
variable is unsigned is actively detrimental, and should be ignored.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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fsnotify: use an enum for group priority constants

And use meaningfull names for the constants.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id:

fsnotify: use an enum for group priority constants

And use meaningfull names for the constants.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240317184154.1200192-10-amir73il@gmail.com>

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fsnotify: pass object pointer and type to fsnotify mark helpers

Instead of passing fsnotify_connp_t, pass the pointer to the marked
object.

Store the object pointer in the connector and move the de

fsnotify: pass object pointer and type to fsnotify mark helpers

Instead of passing fsnotify_connp_t, pass the pointer to the marked
object.

Store the object pointer in the connector and move the definition of
fsnotify_connp_t to internal fsnotify subsystem API, so it is no longer
used by fsnotify backends.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240317184154.1200192-6-amir73il@gmail.com>

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fanotify: merge two checks regarding add of ignore mark

There are two similar checks for adding an ignore mark without
FAN_MARK_IGNORED_SURV_MODIFY, one for the old FAN_MARK_IGNORED flag
and one for

fanotify: merge two checks regarding add of ignore mark

There are two similar checks for adding an ignore mark without
FAN_MARK_IGNORED_SURV_MODIFY, one for the old FAN_MARK_IGNORED flag
and one for the new FAN_MARK_IGNORE flag.

Merge the two checks into a single location.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240317184154.1200192-5-amir73il@gmail.com>

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fanotify: remove unneeded sub-zero check for unsigned value

Unsigned size_t len in copy_fid_info_to_user is checked
for negative value. This check is redundant as it is
always false.

Found by Linux

fanotify: remove unneeded sub-zero check for unsigned value

Unsigned size_t len in copy_fid_info_to_user is checked
for negative value. This check is redundant as it is
always false.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 5e469c830fdb ("fanotify: copy event fid info to user")
Signed-off-by: Nikita Kiryushin <kiryushin@ancud.ru>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <d296ff1c-dcf7-4813-994b-3c4369debb7d@ancud.ru>

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fs: Remove the now superfluous sentinel elements from ctl_table array

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels

fs: Remove the now superfluous sentinel elements from ctl_table array

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel elements ctl_table struct. Special attention was placed in
making sure that an empty directory for fs/verity was created when
CONFIG_FS_VERITY_BUILTIN_SIGNATURES is not defined. In this case we use the
register sysctl call that expects a size.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

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fanotify: allow "weak" fsid when watching a single filesystem

So far, fanotify returns -ENODEV or -EXDEV when trying to set a mark
on a filesystem with a "weak" fsid, namely, zero fsid (e.g. fuse),

fanotify: allow "weak" fsid when watching a single filesystem

So far, fanotify returns -ENODEV or -EXDEV when trying to set a mark
on a filesystem with a "weak" fsid, namely, zero fsid (e.g. fuse), or
non-uniform fsid (e.g. btrfs non-root subvol).

When group is watching inodes all from the same filesystem (or subvol),
allow adding inode marks with "weak" fsid, because there is no ambiguity
regarding which filesystem reports the event.

The first mark added to a group determines if this group is single or
multi filesystem, depending on the fsid at the path of the added mark.

If the first mark added has a "strong" fsid, marks with "weak" fsid
cannot be added and vice versa.

If the first mark added has a "weak" fsid, following marks must have
the same "weak" fsid and the same sb as the first mark.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231130165619.3386452-3-amir73il@gmail.com>

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fanotify: store fsid in mark instead of in connector

Some filesystems like fuse and nfs have zero or non-unique fsid.
We would like to avoid reporting ambiguous fsid in events, so we need
to avoid m

fanotify: store fsid in mark instead of in connector

Some filesystems like fuse and nfs have zero or non-unique fsid.
We would like to avoid reporting ambiguous fsid in events, so we need
to avoid marking objects with same fsid and different sb.

To make this easier to enforce, store the fsid in the marks of the group
instead of in the shared conenctor.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231130165619.3386452-2-amir73il@gmail.com>

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exportfs: add helpers to check if filesystem can encode/decode file handles

The logic of whether filesystem can encode/decode file handles is open
coded in many places.

In preparation to changing t

exportfs: add helpers to check if filesystem can encode/decode file handles

The logic of whether filesystem can encode/decode file handles is open
coded in many places.

In preparation to changing the logic, move the open coded logic into
inline helpers.

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231023180801.2953446-2-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

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fanotify: limit reporting of event with non-decodeable file handles

Commit a95aef69a740 ("fanotify: support reporting non-decodeable file
handles") merged in v6.5-rc1, added the ability to use an fa

fanotify: limit reporting of event with non-decodeable file handles

Commit a95aef69a740 ("fanotify: support reporting non-decodeable file
handles") merged in v6.5-rc1, added the ability to use an fanotify group
with FAN_REPORT_FID mode to watch filesystems that do not support nfs
export, but do know how to encode non-decodeable file handles, with the
newly introduced AT_HANDLE_FID flag.

At the time that this commit was merged, there were no filesystems
in-tree with those traits.

Commit 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles"),
merged in v6.6-rc1, added this trait to overlayfs, thus allowing fanotify
watching of overlayfs with FAN_REPORT_FID mode.

In retrospect, allowing an fanotify filesystem/mount mark on such
filesystem in FAN_REPORT_FID mode will result in getting events with
file handles, without the ability to resolve the filesystem objects from
those file handles (i.e. no open_by_handle_at() support).

For v6.6, the safer option would be to allow this mode for inode marks
only, where the caller has the opportunity to use name_to_handle_at() at
the time of setting the mark. In the future we can revise this decision.

Fixes: a95aef69a740 ("fanotify: support reporting non-decodeable file handles")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20231018100000.2453965-2-amir73il@gmail.com>

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treewide: mark stuff as __ro_after_init

__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "

treewide: mark stuff as __ro_after_init

__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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fanotify: disallow mount/sb marks on kernel internal pseudo fs

Hopefully, nobody is trying to abuse mount/sb marks for watching all
anonymous pipes/inodes.

I cannot think of a good reason to allow

fanotify: disallow mount/sb marks on kernel internal pseudo fs

Hopefully, nobody is trying to abuse mount/sb marks for watching all
anonymous pipes/inodes.

I cannot think of a good reason to allow this - it looks like an
oversight that dated back to the original fanotify API.

Link: https://lore.kernel.org/linux-fsdevel/20230628101132.kvchg544mczxv2pm@quack3/
Fixes: 0ff21db9fcc3 ("fanotify: hooks the fanotify_mark syscall to the vfsmount code")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230629042044.25723-1-amir73il@gmail.com>

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fanotify: support reporting non-decodeable file handles

fanotify users do not always need to decode the file handles reported
with FAN_REPORT_FID.

Relax the restriction that filesystem needs to sup

fanotify: support reporting non-decodeable file handles

fanotify users do not always need to decode the file handles reported
with FAN_REPORT_FID.

Relax the restriction that filesystem needs to support NFS export and
allow reporting file handles from filesystems that only support ecoding
unique file handles.

Even filesystems that do not have export_operations at all can fallback
to use the default FILEID_INO32_GEN encoding, but we use the existence
of export_operations as an indication that the encoded file handles will
be sufficiently unique and that user will be able to compare them to
filesystem objects using AT_HANDLE_FID flag to name_to_handle_at(2).

For filesystems that do not support NFS export, users will have to use
the AT_HANDLE_FID of name_to_handle_at(2) if they want to compare the
object in path to the object fid reported in an event.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230502124817.3070545-5-amir73il@gmail.com>

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fanotify: use pidfd_prepare()

We generally try to avoid installing a file descriptor into the caller's
file descriptor table just to close it again via close_fd() in case an
error occurs. Instead we

fanotify: use pidfd_prepare()

We generally try to avoid installing a file descriptor into the caller's
file descriptor table just to close it again via close_fd() in case an
error occurs. Instead we reserve a file descriptor but don't install it
into the caller's file descriptor table yet. If we fail for other,
unrelated reasons we can just close the reserved file descriptor and if
we make it past all meaningful error paths we just install it. Fanotify
gets this right already for one fd type but not for pidfds.

Use the new pidfd_prepare() helper to reserve a pidfd and a pidfd file
and switch to the more common fd allocation and installation pattern.

Acked-by: Jan Kara <jack@suse.cz>
Message-Id: <20230327-pidfd-file-api-v1-3-5c0e9a3158e4@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

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fanotify: define struct members to hold response decision context

This patch adds a flag, FAN_INFO and an extensible buffer to provide
additional information about response decisions. The buffer co

fanotify: define struct members to hold response decision context

This patch adds a flag, FAN_INFO and an extensible buffer to provide
additional information about response decisions. The buffer contains
one or more headers defining the information type and the length of the
following information. The patch defines one additional information
type, FAN_RESPONSE_INFO_AUDIT_RULE, to audit a rule number. This will
allow for the creation of other information types in the future if other
users of the API identify different needs.

The kernel can be tested if it supports a given info type by supplying
the complete info extension but setting fd to FAN_NOFD. It will return
the expected size but not issue an audit record.

Suggested-by: Steve Grubb <sgrubb@redhat.com>
Link: https://lore.kernel.org/r/2745105.e9J7NaK4W3@x2
Suggested-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20201001101219.GE17860@quack2.suse.cz
Tested-by: Steve Grubb <sgrubb@redhat.com>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <10177cfcae5480926b7176321a28d9da6835b667.1675373475.git.rgb@redhat.com>

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fanotify: Ensure consistent variable type for response

The user space API for the response variable is __u32. This patch makes
sure that the whole path through the kernel uses u32 so that there is
n

fanotify: Ensure consistent variable type for response

The user space API for the response variable is __u32. This patch makes
sure that the whole path through the kernel uses u32 so that there is
no sign extension or truncation of the user space response.

Suggested-by: Steve Grubb <sgrubb@redhat.com>
Link: https://lore.kernel.org/r/12617626.uLZWGnKmhe@x2
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Tested-by: Steve Grubb <sgrubb@redhat.com>
Acked-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <3778cb0b3501bc4e686ba7770b20eb9ab0506cf4.1675373475.git.rgb@redhat.com>

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fs/notify: constify path

Reviewed-by: Matthew Bobrowski <repnop@google.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fanotify: introduce FAN_MARK_IGNORE

This flag is a new way to configure ignore mask which allows adding and
removing the event flags FAN_ONDIR and FAN_EVENT_ON_CHILD in ignore mask.

The legacy FAN_

fanotify: introduce FAN_MARK_IGNORE

This flag is a new way to configure ignore mask which allows adding and
removing the event flags FAN_ONDIR and FAN_EVENT_ON_CHILD in ignore mask.

The legacy FAN_MARK_IGNORED_MASK flag would always ignore events on
directories and would ignore events on children depending on whether
the FAN_EVENT_ON_CHILD flag was set in the (non ignored) mask.

FAN_MARK_IGNORE can be used to ignore events on children without setting
FAN_EVENT_ON_CHILD in the mark's mask and will not ignore events on
directories unconditionally, only when FAN_ONDIR is set in ignore mask.

The new behavior is non-downgradable. After calling fanotify_mark() with
FAN_MARK_IGNORE once, calling fanotify_mark() with FAN_MARK_IGNORED_MASK
on the same object will return EEXIST error.

Setting the event flags with FAN_MARK_IGNORE on a non-dir inode mark
has no meaning and will return ENOTDIR error.

The meaning of FAN_MARK_IGNORED_SURV_MODIFY is preserved with the new
FAN_MARK_IGNORE flag, but with a few semantic differences:

1. FAN_MARK_IGNORED_SURV_MODIFY is required for filesystem and mount
marks and on an inode mark on a directory. Omitting this flag
will return EINVAL or EISDIR error.

2. An ignore mask on a non-directory inode that survives modify could
never be downgraded to an ignore mask that does not survive modify.
With new FAN_MARK_IGNORE semantics we make that rule explicit -
trying to update a surviving ignore mask without the flag
FAN_MARK_IGNORED_SURV_MODIFY will return EEXIST error.

The conveniene macro FAN_MARK_IGNORE_SURV is added for
(FAN_MARK_IGNORE | FAN_MARK_IGNORED_SURV_MODIFY), because the
common case should use short constant names.

Link: https://lore.kernel.org/r/20220629144210.2983229-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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fanotify: cleanups for fanotify_mark() input validations

Create helper fanotify_may_update_existing_mark() for checking for
conflicts between existing mark flags and fanotify_mark() flags.

Use vari

fanotify: cleanups for fanotify_mark() input validations

Create helper fanotify_may_update_existing_mark() for checking for
conflicts between existing mark flags and fanotify_mark() flags.

Use variable mark_cmd to make the checks for mark command bits
cleaner.

Link: https://lore.kernel.org/r/20220629144210.2983229-3-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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fanotify: prepare for setting event flags in ignore mask

Setting flags FAN_ONDIR FAN_EVENT_ON_CHILD in ignore mask has no effect.
The FAN_EVENT_ON_CHILD flag in mask implicitly applies to ignore mas

fanotify: prepare for setting event flags in ignore mask

Setting flags FAN_ONDIR FAN_EVENT_ON_CHILD in ignore mask has no effect.
The FAN_EVENT_ON_CHILD flag in mask implicitly applies to ignore mask and
ignore mask is always implicitly applied to events on directories.

Define a mark flag that replaces this legacy behavior with logic of
applying the ignore mask according to event flags in ignore mask.

Implement the new logic to prepare for supporting an ignore mask that
ignores events on children and ignore mask that does not ignore events
on directories.

To emphasize the change in terminology, also rename ignored_mask mark
member to ignore_mask and use accessors to get only the effective
ignored events or the ignored events and flags.

This change in terminology finally aligns with the "ignore mask"
language in man pages and in most of the comments.

Link: https://lore.kernel.org/r/20220629144210.2983229-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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fanotify: refine the validation checks on non-dir inode mask

Commit ceaf69f8eadc ("fanotify: do not allow setting dirent events in
mask of non-dir") added restrictions about setting dirent events in

fanotify: refine the validation checks on non-dir inode mask

Commit ceaf69f8eadc ("fanotify: do not allow setting dirent events in
mask of non-dir") added restrictions about setting dirent events in the
mask of a non-dir inode mark, which does not make any sense.

For backward compatibility, these restictions were added only to new
(v5.17+) APIs.

It also does not make any sense to set the flags FAN_EVENT_ON_CHILD or
FAN_ONDIR in the mask of a non-dir inode. Add these flags to the
dir-only restriction of the new APIs as well.

Move the check of the dir-only flags for new APIs into the helper
fanotify_events_supported(), which is only called for FAN_MARK_ADD,
because there is no need to error on an attempt to remove the dir-only
flags from non-dir inode.

Fixes: ceaf69f8eadc ("fanotify: do not allow setting dirent events in mask of non-dir")
Link: https://lore.kernel.org/linux-fsdevel/20220627113224.kr2725conevh53u4@quack3.lan/
Link: https://lore.kernel.org/r/20220627174719.2838175-1-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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fanotify: fix incorrect fmode_t casts

Fixes sparce warnings:
fs/notify/fanotify/fanotify_user.c:267:63: sparse:
warning: restricted fmode_t degrades to integer
fs/notify/fanotify/fanotify_user.c:13

fanotify: fix incorrect fmode_t casts

Fixes sparce warnings:
fs/notify/fanotify/fanotify_user.c:267:63: sparse:
warning: restricted fmode_t degrades to integer
fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
warning: restricted fmode_t degrades to integer

FMODE_NONTIFY have bitwise fmode_t type and requires __force attribute
for any casts.

Signed-off-by: Vasily Averin <vvs@openvz.org>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/9adfd6ac-1b89-791e-796b-49ada3293985@openvz.org

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fanotify: do not allow setting dirent events in mask of non-dir

Dirent events (create/delete/move) are only reported on watched
directory inodes, but in fanotify as well as in legacy inotify, it was

fanotify: do not allow setting dirent events in mask of non-dir

Dirent events (create/delete/move) are only reported on watched
directory inodes, but in fanotify as well as in legacy inotify, it was
always allowed to set them on non-dir inode, which does not result in
any meaningful outcome.

Until kernel v5.17, dirent events in fanotify also differed from events
"on child" (e.g. FAN_OPEN) in the information provided in the event.
For example, FAN_OPEN could be set in the mask of a non-dir or the mask
of its parent and event would report the fid of the child regardless of
the marked object.
By contrast, FAN_DELETE is not reported if the child is marked and the
child fid was not reported in the events.

Since kernel v5.17, with fanotify group flag FAN_REPORT_TARGET_FID, the
fid of the child is reported with dirent events, like events "on child",
which may create confusion for users expecting the same behavior as
events "on child" when setting events in the mask on a child.

The desired semantics of setting dirent events in the mask of a child
are not clear, so for now, deny this action for a group initialized
with flag FAN_REPORT_TARGET_FID and for the new event FAN_RENAME.
We may relax this restriction in the future if we decide on the
semantics and implement them.

Fixes: d61fd650e9d2 ("fanotify: introduce group flag FAN_REPORT_TARGET_FID")
Fixes: 8cc3b1ccd930 ("fanotify: wire up FAN_RENAME event")
Link: https://lore.kernel.org/linux-fsdevel/20220505133057.zm5t6vumc4xdcnsg@quack3.lan/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220507080028.219826-1-amir73il@gmail.com

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fanotify: enable "evictable" inode marks

Now that the direct reclaim path is handled we can enable evictable
inode marks.

Link: https://lore.kernel.org/r/20220422120327.3459282-17-amir73il@gmail.co

fanotify: enable "evictable" inode marks

Now that the direct reclaim path is handled we can enable evictable
inode marks.

Link: https://lore.kernel.org/r/20220422120327.3459282-17-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

show more ...

fanotify: use fsnotify group lock helpers

Direct reclaim from fanotify mark allocation context may try to evict
inodes with evictable marks of the same group and hit this deadlock:

[<0>] fsnotify_d

fanotify: use fsnotify group lock helpers

Direct reclaim from fanotify mark allocation context may try to evict
inodes with evictable marks of the same group and hit this deadlock:

[<0>] fsnotify_destroy_mark+0x1f/0x3a
[<0>] fsnotify_destroy_marks+0x71/0xd9
[<0>] __destroy_inode+0x24/0x7e
[<0>] destroy_inode+0x2c/0x67
[<0>] dispose_list+0x49/0x68
[<0>] prune_icache_sb+0x5b/0x79
[<0>] super_cache_scan+0x11c/0x16f
[<0>] shrink_slab.constprop.0+0x23e/0x40f
[<0>] shrink_node+0x218/0x3e7
[<0>] do_try_to_free_pages+0x12a/0x2d2
[<0>] try_to_free_pages+0x166/0x242
[<0>] __alloc_pages_slowpath.constprop.0+0x30c/0x903
[<0>] __alloc_pages+0xeb/0x1c7
[<0>] cache_grow_begin+0x6f/0x31e
[<0>] fallback_alloc+0xe0/0x12d
[<0>] ____cache_alloc_node+0x15a/0x17e
[<0>] kmem_cache_alloc_trace+0xa1/0x143
[<0>] fanotify_add_mark+0xd5/0x2b2
[<0>] do_fanotify_mark+0x566/0x5eb
[<0>] __x64_sys_fanotify_mark+0x21/0x24
[<0>] do_syscall_64+0x6d/0x80
[<0>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Set the FSNOTIFY_GROUP_NOFS flag to prevent going into direct reclaim
from allocations under fanotify group lock and use the safe group lock
helpers.

Link: https://lore.kernel.org/r/20220422120327.3459282-16-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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