From: Josh Durgin <josh.durgin@inktank.com>
Date: Thu, 29 Aug 2013 19:16:42 -0700
Subject: rbd: ignore unmapped snapshots that no longer exist
Git-commit: efadc98aab674153709cc357ba565f04e3164fcd
Patch-mainline: v3.12-rc2
References: FATE#318328 bsc#917884

This prevents erroring out while adding a device when a snapshot
unrelated to the current mapping is deleted between reading the
snapshot context and reading the snapshot names. If the mapped
snapshot name is not found an error still occurs as usual.

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/block/rbd.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4080,8 +4080,13 @@ static u64 rbd_v2_snap_id_by_name(struct
 
 		snap_id = snapc->snaps[which];
 		snap_name = rbd_dev_v2_snap_name(rbd_dev, snap_id);
-		if (IS_ERR(snap_name))
-			break;
+		if (IS_ERR(snap_name)) {
+			/* ignore no-longer existing snapshots */
+			if (PTR_ERR(snap_name) == -ENOENT)
+				continue;
+			else
+				break;
+		}
 		found = !strcmp(name, snap_name);
 		kfree(snap_name);
 	}
