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Commit f09b04a0 authored Dec 21, 2016 by Jan Kara

fsnotify: Remove special handling of mark destruction on group shutdown

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 <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

parent 6b3f05d2

fs/notify/fsnotify.h

+2 −4

Original line number	Original line	Diff line number	Diff line
	@@ -36,10 +36,8 @@ static inline void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
	}		}
	/* prepare for freeing all marks associated with given group */		/* prepare for freeing all marks associated with given group */
	extern void fsnotify_detach_group_marks(struct fsnotify_group *group);		extern void fsnotify_detach_group_marks(struct fsnotify_group *group);
	/*		/* Wait until all marks queued for destruction are destroyed */
	* wait for fsnotify_mark_srcu period to end and free all marks in destroy_list		extern void fsnotify_wait_marks_destroyed(void);
	*/
	extern void fsnotify_mark_destroy_list(void);

	/*		/*
	* update the dentry->d_flags of all of inode's children to indicate if inode cares		* update the dentry->d_flags of all of inode's children to indicate if inode cares

fs/notify/group.c

+6 −4

Original line number	Original line	Diff line number	Diff line
	@@ -66,14 +66,16 @@ void fsnotify_destroy_group(struct fsnotify_group *group)
	*/		*/
	fsnotify_group_stop_queueing(group);		fsnotify_group_stop_queueing(group);

	/* clear all inode marks for this group, attach them to destroy_list */		/* Clear all marks for this group and queue them for destruction */
	fsnotify_detach_group_marks(group);		fsnotify_detach_group_marks(group);

	/*		/*
	* Wait for fsnotify_mark_srcu period to end and free all marks in		* Wait until all marks get really destroyed. We could actually destroy
	* destroy_list		* them ourselves instead of waiting for worker to do it, however that
			* would be racy as worker can already be processing some marks before
			* we even entered fsnotify_destroy_group().
	*/		*/
	fsnotify_mark_destroy_list();		fsnotify_wait_marks_destroyed();

	/*		/*
	* Since we have waited for fsnotify_mark_srcu in		* Since we have waited for fsnotify_mark_srcu in

fs/notify/mark.c

+4 −3

Original line number	Original line	Diff line number	Diff line
	@@ -703,7 +703,7 @@ void fsnotify_init_mark(struct fsnotify_mark *mark,
	* Destroy all marks in destroy_list, waits for SRCU period to finish before		* Destroy all marks in destroy_list, waits for SRCU period to finish before
	* actually freeing marks.		* actually freeing marks.
	*/		*/
	void fsnotify_mark_destroy_list(void)		static void fsnotify_mark_destroy_workfn(struct work_struct *work)
	{		{
	struct fsnotify_mark mark, next;		struct fsnotify_mark mark, next;
	struct list_head private_destroy_list;		struct list_head private_destroy_list;
	@@ -721,7 +721,8 @@ void fsnotify_mark_destroy_list(void)
	}		}
	}		}

	static void fsnotify_mark_destroy_workfn(struct work_struct *work)		/* Wait for all marks queued for destruction to be actually destroyed */
			void fsnotify_wait_marks_destroyed(void)
	{		{
	fsnotify_mark_destroy_list();		flush_delayed_work(&reaper_work);
	}		}