This is a note to let you know that I've just added the patch titled
rbd: drop parent_ref in rbd_dev_unprobe() unconditionally
to the 3.18-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:
rbd-drop-parent_ref-in-rbd_dev_unprobe-unconditionally.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e69b8d414f948c242ad9f3eb2b7e24fba783dbbd Mon Sep 17 00:00:00 2001
From: Ilya Dryomov <idryomov@xxxxxxxxxx>
Date: Mon, 19 Jan 2015 12:06:14 +0300
Subject: rbd: drop parent_ref in rbd_dev_unprobe() unconditionally
From: Ilya Dryomov <idryomov@xxxxxxxxxx>
commit e69b8d414f948c242ad9f3eb2b7e24fba783dbbd upstream.
This effectively reverts the last hunk of 392a9dad7e77 ("rbd: detect
when clone image is flattened").
The problem with parent_overlap != 0 condition is that it's possible
and completely valid to have an image with parent_overlap == 0 whose
parent state needs to be cleaned up on unmap. The next commit, which
drops the "clone image now standalone" logic, opens up another window
of opportunity to hit this, but even without it
# cat parent-ref.sh
#!/bin/bash
rbd create --image-format 2 --size 1 foo
rbd snap create foo@snap
rbd snap protect foo@snap
rbd clone foo@snap bar
rbd resize --allow-shrink --size 0 bar
rbd resize --size 1 bar
DEV=$(rbd map bar)
rbd unmap $DEV
leaves rbd_device/rbd_spec/etc and rbd_client along with ceph_client
hanging around.
My thinking behind calling rbd_dev_parent_put() unconditionally is that
there shouldn't be any requests in flight at that point in time as we
are deep into unmap sequence. Hence, even if rbd_dev_unparent() caused
by flatten is delayed by in-flight requests, it will have finished by
the time we reach rbd_dev_unprobe() caused by unmap, thus turning
unconditional rbd_dev_parent_put() into a no-op.
Fixes: http://tracker.ceph.com/issues/10352
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxxx>
Reviewed-by: Josh Durgin <jdurgin@xxxxxxxxxx>
Reviewed-by: Alex Elder <elder@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/rbd.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -5111,10 +5111,7 @@ static void rbd_dev_unprobe(struct rbd_d
{
struct rbd_image_header *header;
- /* Drop parent reference unless it's already been done (or none) */
-
- if (rbd_dev->parent_overlap)
- rbd_dev_parent_put(rbd_dev);
+ rbd_dev_parent_put(rbd_dev);
/* Free dynamic fields from the header, then zero it out */
Patches currently in stable-queue which might be from idryomov@xxxxxxxxxx are
queue-3.18/rbd-fix-rbd_dev_parent_get-when-parent_overlap-0.patch
queue-3.18/rbd-drop-parent_ref-in-rbd_dev_unprobe-unconditionally.patch
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