[PATCH] md: Improve locking around error handling

The error handling routines don't use proper locking, and so two concurrent
errors could trigger a problem.

So:
  - use test-and-set and test-and-clear to synchonise
    the In_sync bits with the ->degraded count
  - use the spinlock to protect updates to the
    degraded count (could use an atomic_t but that
    would be a bigger change in code, and isn't
    really justified)
  - remove un-necessary locking in raid5

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown
2006-10-03 01:15:53 -07:00
committed by Linus Torvalds
parent 11ce99e625
commit c04be0aa82
3 changed files with 31 additions and 17 deletions
+8 -4
View File
@@ -950,14 +950,16 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
* really dead" tests...
*/
return;
if (test_bit(In_sync, &rdev->flags)) {
if (test_and_clear_bit(In_sync, &rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded++;
spin_unlock_irqrestore(&conf->device_lock, flags);
/*
* if recovery is running, make sure it aborts.
*/
set_bit(MD_RECOVERY_ERR, &mddev->recovery);
}
clear_bit(In_sync, &rdev->flags);
set_bit(Faulty, &rdev->flags);
set_bit(MD_CHANGE_DEVS, &mddev->flags);
printk(KERN_ALERT "raid10: Disk failure on %s, disabling device. \n"
@@ -1033,9 +1035,11 @@ static int raid10_spare_active(mddev_t *mddev)
tmp = conf->mirrors + i;
if (tmp->rdev
&& !test_bit(Faulty, &tmp->rdev->flags)
&& !test_bit(In_sync, &tmp->rdev->flags)) {
&& !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded--;
set_bit(In_sync, &tmp->rdev->flags);
spin_unlock_irqrestore(&conf->device_lock, flags);
}
}