4.4-stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown neilb@suse.com
commit 011abdc9df559ec75779bb7c53a744c69b2a94c6 upstream.
If "re-add" is written to the "state" file for a device which is faulty, this has an effect similar to removing and re-adding the device. It should take up the same slot in the array that it previously had, and an accelerated (e.g. bitmap-based) rebuild should happen.
The slot that "it previously had" is determined by rdev->saved_raid_disk. However this is not set when a device fails (only when a device is added), and it is cleared when resync completes. This means that "re-add" will normally work once, but may not work a second time.
This patch includes two fixes. 1/ when a device fails, record the ->raid_disk value in ->saved_raid_disk before clearing ->raid_disk 2/ when "re-add" is written to a device for which ->saved_raid_disk is not set, fail.
I think this is suitable for stable as it can cause re-adding a device to be forced to do a full resync which takes a lot longer and so puts data at more risk.
Cc: stable@vger.kernel.org (v4.1) Fixes: 97f6cd39da22 ("md-cluster: re-add capabilities") Signed-off-by: NeilBrown neilb@suse.com Reviewed-by: Goldwyn Rodrigues rgoldwyn@suse.com Signed-off-by: Shaohua Li shli@fb.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/md/md.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2690,7 +2690,8 @@ state_store(struct md_rdev *rdev, const err = 0; } } else if (cmd_match(buf, "re-add")) { - if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1)) { + if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) && + rdev->saved_raid_disk >= 0) { /* clear_bit is performed _after_ all the devices * have their local Faulty bit cleared. If any writes * happen in the meantime in the local node, they @@ -8153,6 +8154,7 @@ static int remove_and_add_spares(struct if (mddev->pers->hot_remove_disk( mddev, rdev) == 0) { sysfs_unlink_rdev(mddev, rdev); + rdev->saved_raid_disk = rdev->raid_disk; rdev->raid_disk = -1; removed++; }