linux.git/fs/notify/mark.c, branch v6.10

fsnotify: optimize the case of no permission event watchers

2024-04-04T14:24:16+00:00

Commit e43de7f0862b ("fsnotify: optimize the case of no marks of any type")
optimized the case where there are no fsnotify watchers on any of the
filesystem's objects.

It is quite common for a system to have a single local filesystem and
it is quite common for the system to have some inotify watches on some
config files or directories, so the optimization of no marks at all is
often not in effect.

Permission event watchers, which require high priority group are more
rare, so optimizing the case of no marks og high priority groups can
improve performance for more systems, especially for performance
sensitive io workloads.

Count per-sb watched objects by high priority groups and use that the
optimize out the call to __fsnotify_parent() and fsnotify() in fsnotify
permission hooks.

Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Message-Id: <20240317184154.1200192-11-amir73il@gmail.com>

fsnotify: lazy attach fsnotify_sb_info state to sb

2024-04-04T14:24:16+00:00

Define a container struct fsnotify_sb_info to hold per-sb state,
including the reference to sb marks connector.

Allocate the fsnotify_sb_info state before attaching connector to any
object on the sb and free it only when killing sb.

This state is going to be used for storing per priority watched objects
counters.

Suggested-by: Jan Kara 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Message-Id: <20240317184154.1200192-8-amir73il@gmail.com>

fsnotify: create helper fsnotify_update_sb_watchers()

2024-04-04T14:24:16+00:00

We would like to count watched objects by priority group, so we will need
to update the watched object counter after adding/removing marks.

Create a helper fsnotify_update_sb_watchers() and call it after
attaching/detaching a mark, instead of fsnotify_{get,put}_sb_watchers()
only after attaching/detaching a connector.

Soon, we will use this helper to count watched objects by the highest
watching priority group.

Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Message-Id: <20240317184154.1200192-7-amir73il@gmail.com>

fsnotify: pass object pointer and type to fsnotify mark helpers

2024-04-04T14:24:16+00:00

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

fsnotify: create helpers to get sb and connp from object

2024-04-04T14:23:46+00:00

In preparation to passing an object pointer to add/remove/find mark
helpers, create helpers to get sb and connp by object type.

Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Message-Id: <20240317184154.1200192-3-amir73il@gmail.com>

fsnotify: rename fsnotify_{get,put}_sb_connectors()

2024-04-04T14:21:12+00:00

Instead of counting the number of connectors in an sb, we would like
to count the number of watched objects per priority group.

As a start, create an accessor fsnotify_sb_watched_objects() to
s_fsnotify_connectors and rename the fsnotify_{get,put}_sb_connectors()
helpers to fsnotify_{get,put}_sb_watchers() to better describes the
counter.

Increment the counter at the end of fsnotify_attach_connector_to_object()
if connector was attached instead of decrementing it on race to connect.

This is fine, because fsnotify_delete_sb() cannot be running in parallel
to fsnotify_attach_connector_to_object() which requires a reference to
a filesystem object.

Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Message-Id: <20240317184154.1200192-2-amir73il@gmail.com>

fanotify: store fsid in mark instead of in connector

2023-12-01T09:55:21+00:00

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 
Signed-off-by: Jan Kara 
Message-Id: <20231130165619.3386452-2-amir73il@gmail.com>

fsnotify: allow adding an inode mark without pinning inode

2022-04-25T12:42:45+00:00

fsnotify_add_mark() and variants implicitly take a reference on inode
when attaching a mark to an inode.

Make that behavior opt-out with the mark flag FSNOTIFY_MARK_FLAG_NO_IREF.

Instead of taking the inode reference when attaching connector to inode
and dropping the inode reference when detaching connector from inode,
take the inode reference on attach of the first mark that wants to hold
an inode reference and drop the inode reference on detach of the last
mark that wants to hold an inode reference.

Backends can "upgrade" an existing mark to take an inode reference, but
cannot "downgrade" a mark with inode reference to release the refernce.

This leaves the choice to the backend whether or not to pin the inode
when adding an inode mark.

This is intended to be used when adding a mark with ignored mask that is
used for optimization in cases where group can afford getting unneeded
events and reinstate the mark with ignored mask when inode is accessed
again after being evicted.

Link: https://lore.kernel.org/r/20220422120327.3459282-12-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: create helpers for group mark_mutex lock

2022-04-25T12:37:22+00:00

Create helpers to take and release the group mark_mutex lock.

Define a flag FSNOTIFY_GROUP_NOFS in fsnotify_group that determines
if the mark_mutex lock is fs reclaim safe or not.  If not safe, the
lock helpers take the lock and disable direct fs reclaim.

In that case we annotate the mutex with a different lockdep class to
express to lockdep that an allocation of mark of an fs reclaim safe group
may take the group lock of another "NOFS" group to evict inodes.

For now, converted only the callers in common code and no backend
defines the NOFS flag.  It is intended to be set by fanotify for
evictable marks support.

Link: https://lore.kernel.org/r/20220422120327.3459282-7-amir73il@gmail.com
Suggested-by: Jan Kara 
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: make allow_dups a property of the group

2022-04-25T12:37:18+00:00

Instead of passing the allow_dups argument to fsnotify_add_mark()
as an argument, define the group flag FSNOTIFY_GROUP_DUPS to express
the allow_dups behavior and set this behavior at group creation time
for all calls of fsnotify_add_mark().

Rename the allow_dups argument to generic add_flags argument for future
use.

Link: https://lore.kernel.org/r/20220422120327.3459282-6-amir73il@gmail.com
Suggested-by: Jan Kara 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara