| From | Andi Kleen <> | Subject | [PATCH] [86/139] md: fix bug with re-adding of partially recovered device. | Date | Tue, 1 Feb 2011 16:44:43 -0800 (PST) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: NeilBrown <neilb@suse.de>
commit 1a855a0606653d2d82506281e2c686bacb4b2f45 upstream.
With v0.90 metadata, a hot-spare does not become a full member of the array until recovery is complete. So if we re-add such a device to the array, we know that all of it is as up-to-date as the event count would suggest, and so it a bitmap-based recovery is possible.
However with v1.x metadata, the hot-spare immediately becomes a full member of the array, but it record how much of the device has been recovered. If the array is stopped and re-assembled recovery starts from this point.
When such a device is hot-added to an array we currently lose the 'how much is recovered' information and incorrectly included it as a full in-sync member (after bitmap-based fixup). This is wrong and unsafe and could corrupt data.
So be more careful about setting saved_raid_disk - which is what guides the re-adding of devices back into an array. The new code matches the code in slot_store which does a similar thing, which is encouraging.
This is suitable for any -stable kernel.
Reported-by: "Dailey, Nate" <Nate.Dailey@stratus.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- drivers/md/md.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
Index: linux-2.6.35.y/drivers/md/md.c =================================================================== --- linux-2.6.35.y.orig/drivers/md/md.c +++ linux-2.6.35.y/drivers/md/md.c @@ -5109,7 +5109,7 @@ static int add_new_disk(mddev_t * mddev, PTR_ERR(rdev)); return PTR_ERR(rdev); } - /* set save_raid_disk if appropriate */ + /* set saved_raid_disk if appropriate */ if (!mddev->persistent) { if (info->state & (1<<MD_DISK_SYNC) && info->raid_disk < mddev->raid_disks) @@ -5119,7 +5119,10 @@ static int add_new_disk(mddev_t * mddev, } else super_types[mddev->major_version]. validate_super(mddev, rdev); - rdev->saved_raid_disk = rdev->raid_disk; + if (test_bit(In_sync, &rdev->flags)) + rdev->saved_raid_disk = rdev->raid_disk; + else + rdev->saved_raid_disk = -1; clear_bit(In_sync, &rdev->flags); /* just to be sure */ if (info->state & (1<<MD_DISK_WRITEMOSTLY))
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