[PATCH 3.13 134/163] md/raid1: update next_resync under resync_lock.

Kamal Mostafa kamal at canonical.com
Thu Oct 9 21:02:39 UTC 2014 -stable review patch.  If anyone has any objections, please let me know.


From: NeilBrown <neilb at suse.de>

commit c2fd4c94deedb89ac1746c4a53219be499372c06 upstream.

raise_barrier() uses next_resync as part of its calculations, so it
really should be updated first, instead of afterwards.

next_resync is always used under resync_lock so update it under
resync lock to, just before it is used.  That is safest.

This could cause normal IO and resync IO to interact badly so
it suitable for -stable.

Fixes: 79ef3a8aa1cb1523cc231c9a90a278333c21f761
Signed-off-by: NeilBrown <neilb at suse.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/md/raid1.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 11d0bd8..5ad11da 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -829,7 +829,7 @@ static void flush_pending_writes(struct r1conf *conf)
  *    there is no normal IO happeing.  It must arrange to call
  *    lower_barrier when the particular background IO completes.
-static void raise_barrier(struct r1conf *conf)
+static void raise_barrier(struct r1conf *conf, sector_t sector_nr)
@@ -839,6 +839,7 @@ static void raise_barrier(struct r1conf *conf)
 	/* block any new IO from starting */
+	conf->next_resync = sector_nr;
 	/* For these conditions we must wait:
 	 * A: while the array is in frozen state
@@ -2540,9 +2541,8 @@ static sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipp
 	bitmap_cond_end_sync(mddev->bitmap, sector_nr);
 	r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
-	raise_barrier(conf);
-	conf->next_resync = sector_nr;
+	raise_barrier(conf, sector_nr);

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