linux.git/fs/notify/mark.c, branch v4.13

fsnotify: remove a stray unlock

2017-04-24T14:41:28+00:00

We recently shifted this code around, so we're no longer holding the
lock on this path.

Fixes: 755b5bc681eb ("fsnotify: Remove indirection from mark list addition")
Signed-off-by: Dan Carpenter 
Signed-off-by: Jan Kara

fsnotify: Move ->free_mark callback to fsnotify_ops

2017-04-10T15:37:36+00:00

Pointer to ->free_mark callback unnecessarily occupies one long in each
fsnotify_mark although they are the same for all marks from one
notification group. Move the callback pointer to fsnotify_ops.

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Add group pointer in fsnotify_init_mark()

2017-04-10T15:37:36+00:00

Currently we initialize mark->group only in fsnotify_add_mark_lock().
However we will need to access fsnotify_ops of corresponding group from
fsnotify_put_mark() so we need mark->group initialized earlier. Do that
in fsnotify_init_mark() which has a consequence that once
fsnotify_init_mark() is called on a mark, the mark has to be destroyed
by fsnotify_put_mark().

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Remove fsnotify_detach_group_marks()

2017-04-10T15:37:36+00:00

The function is already mostly contained in what
fsnotify_clear_marks_by_group() does. Just update that function to not
select marks when all of them should be destroyed and remove
fsnotify_detach_group_marks().

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Rename fsnotify_clear_marks_by_group_flags()

2017-04-10T15:37:36+00:00

The _flags() suffix in the function name was more confusing than
explaining so just remove it. Also rename the argument from 'flags' to
'type' to better explain what the function expects.

Reviewed-by: Miklos Szeredi 
Suggested-by: Amir Goldstein 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Remove fsnotify_set_mark_{,ignored_}mask_locked()

2017-04-10T15:37:36+00:00

These helpers are now only a simple assignment and just obfuscate
what is going on. Remove them.

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Provide framework for dropping SRCU lock in ->handle_event

2017-04-10T15:37:36+00:00

fanotify wants to drop fsnotify_mark_srcu lock when waiting for response
from userspace so that the whole notification subsystem is not blocked
during that time. This patch provides a framework for safely getting
mark reference for a mark found in the object list which pins the mark
in that list. We can then drop fsnotify_mark_srcu, wait for userspace
response and then safely continue iteration of the object list once we
reaquire fsnotify_mark_srcu.

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Remove special handling of mark destruction on group shutdown

2017-04-10T15:37:36+00:00

Currently we queue all marks for destruction on group shutdown and then
destroy them from fsnotify_destroy_group() instead from a worker thread
which is the usual path. However worker can already be processing some
list of marks to destroy so this does not make 100% all marks are really
destroyed by the time group is shut down. This isn't a big problem as
each mark holds group reference and thus group stays partially alive
until all marks are really freed but there's no point in complicating
our lives - just wait for the delayed work to be finished instead.

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Detach mark from object list when last reference is dropped

2017-04-10T15:37:36+00:00

Instead of removing mark from object list from fsnotify_detach_mark(),
remove the mark when last reference to the mark is dropped. This will
allow fanotify to wait for userspace response to event without having to
hold onto fsnotify_mark_srcu.

To avoid pinning inodes by elevated refcount (and thus e.g. delaying
file deletion) while someone holds mark reference, we detach connector
from the object also from fsnotify_destroy_marks() and not only after
removing last mark from the list as it was now.

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: Move queueing of mark for destruction into fsnotify_put_mark()

2017-04-10T15:37:35+00:00

Currently we queue mark into a list of marks for destruction in
__fsnotify_free_mark() and keep the last mark reference dangling. After the
worker waits for SRCU period, it drops the last reference to the mark
which frees it. This scheme has the disadvantage that if we hold
reference to a mark and drop and reacquire SRCU lock, the mark can get
freed immediately which is slightly inconvenient and we will need to
avoid this in the future.

Move to a scheme where queueing of mark into a list of marks for
destruction happens when the last reference to the mark is dropped. Also
drop reference to the mark held by group list already when mark is
removed from that list instead of dropping it only from the destruction
worker.

Reviewed-by: Miklos Szeredi 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara