[PATCH 4.20 013/183] ceph: avoid repeatedly adding inode to mdsc->snap_flush_list

From: Greg Kroah-Hartman
Date: Mon Feb 25 2019 - 16:28:27 EST


4.20-stable review patch. If anyone has any objections, please let me know.

------------------

From: Yan, Zheng <zyan@xxxxxxxxxx>

commit 04242ff3ac0abbaa4362f97781dac268e6c3541a upstream.

Otherwise, mdsc->snap_flush_list may get corrupted.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
Reviewed-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/ceph/snap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -616,7 +616,8 @@ int __ceph_finish_cap_snap(struct ceph_i
capsnap->size);

spin_lock(&mdsc->snap_flush_lock);
- list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);
+ if (list_empty(&ci->i_snap_flush_item))
+ list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);
spin_unlock(&mdsc->snap_flush_lock);
return 1; /* caller may want to ceph_flush_snaps */
}