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authorNeilBrown <neilb@suse.de>2006-01-06 00:20:24 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-06 08:34:04 -0800
commit9910f16af35419a5382fa7850eecc220103036fa (patch)
tree3b5145b8a706e03a6f2b4da4bd84fe98c83de31a /drivers/md/raid5.c
parentcf30a473a02901fe4db37abc0b0fa26dd5ba3f72 (diff)
[PATCH] md: fix up some rdev rcu locking in raid5/6
There is this "FIXME" comment with a typo in it!! that been annoying me for days, so I just had to remove it. conf->disks[i].rdev should only be accessed if - we know we hold a reference or - the mddev->reconfig_sem is down or - we have a rcu_readlock handle_stripe was referencing rdev in three places without any of these. For the first two, get an rcu_readlock. For the last, the same access (md_sync_acct call) is made a little later after the rdev has been claimed under and rcu_readlock, if R5_Syncio is set. So just use that access... However R5_Syncio isn't really needed as the 'syncing' variable contains the same information. So use that instead. Issues, comment, and fix are identical in raid5 and raid6. Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/md/raid5.c')
-rw-r--r--drivers/md/raid5.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0d016a844ec6..0222ba1a6d35 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -961,11 +961,11 @@ static void handle_stripe(struct stripe_head *sh)
syncing = test_bit(STRIPE_SYNCING, &sh->state);
/* Now to look around and see what can be done */
+ rcu_read_lock();
for (i=disks; i--; ) {
mdk_rdev_t *rdev;
dev = &sh->dev[i];
clear_bit(R5_Insync, &dev->flags);
- clear_bit(R5_Syncio, &dev->flags);
PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
i, dev->flags, dev->toread, dev->towrite, dev->written);
@@ -1004,7 +1004,7 @@ static void handle_stripe(struct stripe_head *sh)
non_overwrite++;
}
if (dev->written) written++;
- rdev = conf->disks[i].rdev; /* FIXME, should I be looking rdev */
+ rdev = rcu_dereference(conf->disks[i].rdev);
if (!rdev || !test_bit(In_sync, &rdev->flags)) {
/* The ReadError flag will just be confusing now */
clear_bit(R5_ReadError, &dev->flags);
@@ -1017,6 +1017,7 @@ static void handle_stripe(struct stripe_head *sh)
} else
set_bit(R5_Insync, &dev->flags);
}
+ rcu_read_unlock();
PRINTK("locked=%d uptodate=%d to_read=%d"
" to_write=%d failed=%d failed_num=%d\n",
locked, uptodate, to_read, to_write, failed, failed_num);
@@ -1028,10 +1029,13 @@ static void handle_stripe(struct stripe_head *sh)
int bitmap_end = 0;
if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
- mdk_rdev_t *rdev = conf->disks[i].rdev;
+ mdk_rdev_t *rdev;
+ rcu_read_lock();
+ rdev = rcu_dereference(conf->disks[i].rdev);
if (rdev && test_bit(In_sync, &rdev->flags))
/* multiple read failures in one stripe */
md_error(conf->mddev, rdev);
+ rcu_read_unlock();
}
spin_lock_irq(&conf->device_lock);
@@ -1180,9 +1184,6 @@ static void handle_stripe(struct stripe_head *sh)
locked++;
PRINTK("Reading block %d (sync=%d)\n",
i, syncing);
- if (syncing)
- md_sync_acct(conf->disks[i].rdev->bdev,
- STRIPE_SECTORS);
}
}
}
@@ -1326,7 +1327,6 @@ static void handle_stripe(struct stripe_head *sh)
clear_bit(STRIPE_DEGRADED, &sh->state);
locked++;
set_bit(STRIPE_INSYNC, &sh->state);
- set_bit(R5_Syncio, &dev->flags);
}
}
if (syncing && locked == 0 && test_bit(STRIPE_INSYNC, &sh->state)) {
@@ -1392,7 +1392,7 @@ static void handle_stripe(struct stripe_head *sh)
rcu_read_unlock();
if (rdev) {
- if (test_bit(R5_Syncio, &sh->dev[i].flags))
+ if (syncing)
md_sync_acct(rdev->bdev, STRIPE_SECTORS);
bi->bi_bdev = rdev->bdev;