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md/raid1: extend spinlock to protect raid1_end_read_request against inconsistencies

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raid1_end_read_request() assumes that the In_sync bits are consistent
with the ->degaded count.
raid1_spare_active updates the In_sync bit before the ->degraded count
and so exposes an inconsistency, as does error()
So extend the spinlock in raid1_spare_active() and error() to hide those
inconsistencies.

This should probably be part of
  Commit: 34cab6f420 ("md/raid1: fix test for 'was read error from
  last working device'.")
as it addresses the same issue.  It fixes the same bug and should go
to -stable for same reasons.

Fixes: 76073054c9 ("md/raid1: clean up read_balance.")
Cc: stable@vger.kernel.org (v3.0+)
Signed-off-by: NeilBrown <neilb@suse.com>
This commit is contained in:
NeilBrown 2015-07-27 11:48:52 +10:00
parent 74d33293e4
commit 423f04d63c
1 changed files with 6 additions and 4 deletions
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10
drivers/md/raid1.c
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@ -1476,6 +1476,7 @@ static void error(struct mddev *mddev, struct md_rdev *rdev)
{
char b[BDEVNAME_SIZE];
struct r1conf *conf = mddev->private;
unsigned long flags;
/*
* If it is not operational, then we have already marked it as dead
@ -1495,14 +1496,13 @@ static void error(struct mddev *mddev, struct md_rdev *rdev)
return;
}
set_bit(Blocked, &rdev->flags);
spin_lock_irqsave(&conf->device_lock, flags);
if (test_and_clear_bit(In_sync, &rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded++;
set_bit(Faulty, &rdev->flags);
spin_unlock_irqrestore(&conf->device_lock, flags);
} else
set_bit(Faulty, &rdev->flags);
spin_unlock_irqrestore(&conf->device_lock, flags);
/*
* if recovery is running, make sure it aborts.
*/
@ -1568,7 +1568,10 @@ static int raid1_spare_active(struct mddev *mddev)
* Find all failed disks within the RAID1 configuration
* and mark them readable.
* Called under mddev lock, so rcu protection not needed.
* device_lock used to avoid races with raid1_end_read_request
* which expects 'In_sync' flags and ->degraded to be consistent.
*/
spin_lock_irqsave(&conf->device_lock, flags);
for (i = 0; i < conf->raid_disks; i++) {
struct md_rdev *rdev = conf->mirrors[i].rdev;
struct md_rdev *repl = conf->mirrors[conf->raid_disks + i].rdev;
@ -1599,7 +1602,6 @@ static int raid1_spare_active(struct mddev *mddev)
sysfs_notify_dirent_safe(rdev->sysfs_state);
}
}
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded -= count;
spin_unlock_irqrestore(&conf->device_lock, flags);