ceph: avoid repeatedly adding inode to mdsc->snap_flush_list

ukernel · idryomov · commit 04242ff3ac0a · 2019-02-18T18:08:29.000+01:00
Otherwise, mdsc-&gt;snap_flush_list may get corrupted.

Cc: stable@vger.kernel.org
Signed-off-by: "Yan, Zheng" &lt;zyan@redhat.com&gt;
Reviewed-by: Ilya Dryomov &lt;idryomov@gmail.com&gt;
Signed-off-by: Ilya Dryomov &lt;idryomov@gmail.com&gt;
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
@@ -616,7 +616,8 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
 	     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 */
 }

Original file line number	Diff line number	Diff line change
`@@ -616,7 +616,8 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci,`
`616`	`616`	`capsnap->size);`
`617`	`617`
`618`	`618`	`spin_lock(&mdsc->snap_flush_lock);`
`619`		`- list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);`
	`619`	`+ if (list_empty(&ci->i_snap_flush_item))`
	`620`	`+ list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list);`
`620`	`621`	`spin_unlock(&mdsc->snap_flush_lock);`
`621`	`622`	`return 1; /* caller may want to ceph_flush_snaps */`
`622`	`623`	`}`