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: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/notify/fsnotify.h | 6 ++----
fs/notify/group.c | 10 ++++++----
fs/notify/mark.c | 7 ++++---
3 files changed, 12 insertions(+), 11 deletions(-)
diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h
index 24bc549e9709..cbb9df3b10d0 100644
--- a/fs/notify/fsnotify.h
+++ b/fs/notify/fsnotify.h
@@ -36,10 +36,8 @@ static inline void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
}
/* prepare for freeing all marks associated with given group */
extern void fsnotify_detach_group_marks(struct fsnotify_group *group);
-/*
- * wait for fsnotify_mark_srcu period to end and free all marks in destroy_list
- */
-extern void fsnotify_mark_destroy_list(void);
+/* Wait until all marks queued for destruction are destroyed */
+extern void fsnotify_wait_marks_destroyed(void);
/*
* update the dentry->d_flags of all of inode's children to indicate if inode cares
diff --git a/fs/notify/group.c b/fs/notify/group.c
index fbe3cbebec16..0fb4aadcc19f 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -66,14 +66,16 @@ void fsnotify_destroy_group(struct fsnotify_group *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);
/*
- * Wait for fsnotify_mark_srcu period to end and free all marks in
- * destroy_list
+ * Wait until all marks get really destroyed. We could actually destroy
+ * 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
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 648f198f56ec..e22e87bbcd84 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -685,7 +685,7 @@ void fsnotify_init_mark(struct fsnotify_mark *mark,
* Destroy all marks in destroy_list, waits for SRCU period to finish before
* 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 list_head private_destroy_list;
@@ -703,7 +703,8 @@ 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);
}
--
2.10.2
