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[PATCH] md: Improve locking around error handling

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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
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16
drivers/md/raid1.c
View file

@ -959,14 +959,16 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
* normal single drive
*/
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 "raid1: Disk failure on %s, disabling device. \n"
@ -1022,9 +1024,11 @@ static int raid1_spare_active(mddev_t *mddev)
mdk_rdev_t *rdev = conf->mirrors[i].rdev;
if (rdev
&& !test_bit(Faulty, &rdev->flags)
&& !test_bit(In_sync, &rdev->flags)) {
&& !test_and_set_bit(In_sync, &rdev->flags)) {
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded--;
set_bit(In_sync, &rdev->flags);
spin_unlock_irqrestore(&conf->device_lock, flags);
}
}
@ -2048,7 +2052,7 @@ static int raid1_reshape(mddev_t *mddev)
mirror_info_t *newmirrors;
conf_t *conf = mddev_to_conf(mddev);
int cnt, raid_disks;
unsigned long flags;
int d, d2;
/* Cannot change chunk_size, layout, or level */
@ -2107,7 +2111,9 @@ static int raid1_reshape(mddev_t *mddev)
kfree(conf->poolinfo);
conf->poolinfo = newpoolinfo;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded += (raid_disks - conf->raid_disks);
spin_unlock_irqrestore(&conf->device_lock, flags);
conf->raid_disks = mddev->raid_disks = raid_disks;
mddev->delta_disks = 0;