kernel/git/stable/linux-stable.git/fs/notify/mark.c, branch linux-4.14.y

fsnotify: fix wrong lockdep annotations

2022-06-14T14:53:48+00:00

[ Upstream commit 623af4f538b5df9b416e1b82f720af7371b4c771 ] Commit 6960b0d909cd ("fsnotify: change locking order") changed some of the mark_mutex locks in direct reclaim path to use: mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); This change is explained: "...It uses nested locking to avoid deadlock in case we do the final iput() on an inode which still holds marks and thus would take the mutex again when calling fsnotify_inode_delete() in destroy_inode()." The problem is that the mutex_lock_nested() is not a nested lock at all. In fact, it has the opposite effect of preventing lockdep from warning about a very possible deadlock. Due to these wrong annotations, a deadlock that was introduced with nfsd filecache in kernel v5.4 went unnoticed in v5.4.y for over two years until it was reported recently by Khazhismel Kumykov, only to find out that the deadlock was already fixed in kernel v5.5. Fix the wrong lockdep annotations. Cc: Khazhismel Kumykov Fixes: 6960b0d909cd ("fsnotify: change locking order") Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/ Link: https://lore.kernel.org/r/20220422120327.3459282-4-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Signed-off-by: Sasha Levin

fsnotify: fix pinning group in fsnotify_prepare_user_wait()

2017-11-30T08:40:47+00:00

commit 9a31d7ad997f55768c687974ce36b759065b49e5 upstream. Blind increment of group's user_waits is not enough, we could be far enough in the group's destruction that it isn't taken into account (i.e. grabbing the mark ref afterwards doesn't guarantee that it was the ref coming from the _group_ that was grabbed). Instead we need to check (under lock) that the mark is still attached to the group after having obtained a ref to the mark. If not, skip it. Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi Fixes: 9385a84d7e1f ("fsnotify: Pass fsnotify_iter_info into handle_event handler") Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

fsnotify: clean up fsnotify_prepare/finish_user_wait()

2017-11-30T08:40:47+00:00

commit 24c20305c7fc8959836211cb8c50aab93ae0e54f upstream. This patch doesn't actually fix any bug, just paves the way for fixing mark and group pinning. Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman

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