From 9910f16af35419a5382fa7850eecc220103036fa Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 6 Jan 2006 00:20:24 -0800 Subject: [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/raid5.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'drivers/md/raid5.c') diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 0d016a844ec..0222ba1a6d3 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; -- cgit v1.2.3-70-g09d2