rbd: require stable pages if message data CRCs are enabled

commit bae818ee1577c27356093901a0ea48f672eda514 upstream.

rbd requires stable pages, as it performs a crc of the page data before
they are send to the OSDs.

But since kernel 3.9 (patch 1d1d1a767206fbe5d4c69493b7e6d2a8d08cc0a0
"mm: only enforce stable page writes if the backing device requires
it") it is not assumed anymore that block devices require stable pages.

This patch sets the necessary flag to get stable pages back for rbd.

In a ceph installation that provides multiple ext4 formatted rbd
devices "bad crc" messages appeared regularly (ca 1 message every 1-2
minutes on every OSD that provided the data for the rbd) in the
OSD-logs before this patch. After this patch this messages are pretty
much gone (only ca 1-2 / month / OSD).

Signed-off-by: Ronny Hegewald <Ronny.Hegewald@online.de>
[idryomov@gmail.com: require stable pages only in crc case, changelog]
[idryomov@gmail.com: backport to 3.9-3.17: context]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 66f6327309690366d4869e12a88e576f4c5652f7..6d3ec00ba8454315f29951ea8aa189a29914c3ae 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3441,6 +3441,9 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
        blk_queue_io_opt(q, segment_size);
 
        blk_queue_merge_bvec(q, rbd_merge_bvec);
+       if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC))
+               q->backing_dev_info.capabilities |= BDI_CAP_STABLE_WRITES;
+
        disk->queue = q;
 
        q->queuedata = rbd_dev;