This is a note to let you know that I've just added the patch titled
gfs2: Cancel remote delete work asynchronously
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gfs2-cancel-remote-delete-work-asynchronously.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c5d52877bbd55586a8a5e379ca7eb37b7d7d94ce
Author: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Date: Mon Oct 11 20:53:02 2021 +0200
gfs2: Cancel remote delete work asynchronously
[ Upstream commit 486408d690e130c3adacf816754b97558d715f46 ]
In gfs2_inode_lookup and gfs2_create_inode, we're calling
gfs2_cancel_delete_work which currently cancels any remote delete work
(delete_work_func) synchronously. This means that if the work is
currently running, it will wait for it to finish. We're doing this to
pevent a previous instance of an inode from having any influence on the
next instance.
However, delete_work_func uses gfs2_inode_lookup internally, and we can
end up in a deadlock when delete_work_func gets interrupted at the wrong
time. For example,
(1) An inode's iopen glock has delete work queued, but the inode
itself has been evicted from the inode cache.
(2) The delete work is preempted before reaching gfs2_inode_lookup.
(3) Another process recreates the inode (gfs2_create_inode). It tries
to cancel any outstanding delete work, which blocks waiting for
the ongoing delete work to finish.
(4) The delete work calls gfs2_inode_lookup, which blocks waiting for
gfs2_create_inode to instantiate and unlock the new inode =>
deadlock.
It turns out that when the delete work notices that its inode has been
re-instantiated, it will do nothing. This means that it's safe to
cancel the delete work asynchronously. This prevents the kind of
deadlock described above.
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Bob Peterson <rpeterso@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 1f3902ecddedd..fea68ed127b89 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1920,7 +1920,7 @@ bool gfs2_queue_delete_work(struct gfs2_glock *gl, unsigned long delay)
void gfs2_cancel_delete_work(struct gfs2_glock *gl)
{
- if (cancel_delayed_work_sync(&gl->gl_delete)) {
+ if (cancel_delayed_work(&gl->gl_delete)) {
clear_bit(GLF_PENDING_DELETE, &gl->gl_flags);
gfs2_glock_put(gl);
}
