| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.16 330/357] md/raid1: be more cautious where we read-balance during resync. | Date | Fri, 3 Oct 2014 14:31:56 -0700 |
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3.16-stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown <neilb@suse.de>
commit c6d119cf1b5a778e9ed60a006e2a434fcc4471a2 upstream.
commit 79ef3a8aa1cb1523cc231c9a90a278333c21f761 made it possible for reads to happen concurrently with resync. This means that we need to be more careful where read_balancing is allowed during resync - we can no longer be sure that any resync that has already started will definitely finish.
So keep read_balancing to before recovery_cp, which is conservative but safe.
This bug makes it possible to read from a device that doesn't have up-to-date data, so it can cause data corruption. So it is suitable for any kernel since 3.11.
Fixes: 79ef3a8aa1cb1523cc231c9a90a278333c21f761 Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/md/raid1.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)
--- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -540,11 +540,7 @@ static int read_balance(struct r1conf *c has_nonrot_disk = 0; choose_next_idle = 0; - if (conf->mddev->recovery_cp < MaxSector && - (this_sector + sectors >= conf->next_resync)) - choose_first = 1; - else - choose_first = 0; + choose_first = (conf->mddev->recovery_cp < this_sector + sectors); for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) { sector_t dist;
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