[PATCH] dm: Handle READA requests in dm-mpath.c

READA errors failing with EWOULDBLOCK/EAGAIN do not constitute a valid
reason for failing the path; this lead to erratic errors on DM multipath
devices.  This error can be safely propagated upwards without failing the
path.

Acked-by: Kevin Corry <kevcorry@us.ibm.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 1e97b3c12bd5..0c1b8520ef86 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -985,6 +985,9 @@ static int do_end_io(struct multipath *m, struct bio *bio,
         if (!error)
                 return 0;       /* I/O complete */
 
+        if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
+                return error;
+
         spin_lock(&m->lock);
         if (!m->nr_valid_paths) {
                 if (!m->queue_if_no_path || m->suspended) {