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Commit f5b67ae8 authored by NeilBrown's avatar NeilBrown Committed by Shaohua Li
Browse files

md: be extra careful not to take a reference to a Faulty device. 



It is important that we never increment rdev->nr_pending on a Faulty
device as ->hot_remove_disk() assumes that once the Faulty flag is visible
no code will take a new reference.

Some places take a new reference after only check In_sync.  This should
be safe as the two are changed together.  However to make the code more
obviously safe, add checks for 'Faulty' as well.

Note: the actual rule is:
  Never increment nr_pending if  Faulty is set and Blocked is clear,
  never clear Faulty, and never set Blocked without holding a reference
  through nr_pending.

fix build error (Shaohua)
Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 40cf2123

drivers/md/multipath.c

+2 −1
Original line number Diff line number Diff line
@@ -43,7 +43,8 @@ static int multipath_map (struct mpconf *conf) 
	rcu_read_lock();

	for (i = 0; i < disks; i++) {

		struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);

		if (rdev && test_bit(In_sync, &rdev->flags)) {

		if (rdev && test_bit(In_sync, &rdev->flags) &&

		    !test_bit(Faulty, &rdev->flags)) {

			atomic_inc(&rdev->nr_pending);

			rcu_read_unlock();

			return i;

drivers/md/raid10.c

+6 −0
Original line number Diff line number Diff line
@@ -2287,6 +2287,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10 
			rdev = rcu_dereference(conf->mirrors[d].rdev);

			if (rdev &&

			    test_bit(In_sync, &rdev->flags) &&

			    !test_bit(Faulty, &rdev->flags) &&

			    is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,

					&first_bad, &bad_sectors) == 0) {

				atomic_inc(&rdev->nr_pending);
@@ -2339,6 +2340,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10 
			d = r10_bio->devs[sl].devnum;

			rdev = rcu_dereference(conf->mirrors[d].rdev);

			if (!rdev ||

			    test_bit(Faulty, &rdev->flags) ||

			    !test_bit(In_sync, &rdev->flags))

				continue;
@@ -2378,6 +2380,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10 
			d = r10_bio->devs[sl].devnum;

			rdev = rcu_dereference(conf->mirrors[d].rdev);

			if (!rdev ||

			    test_bit(Faulty, &rdev->flags) ||

			    !test_bit(In_sync, &rdev->flags))

				continue;
@@ -2953,6 +2956,7 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr, 
			mreplace = rcu_dereference(mirror->replacement);



			if ((mrdev == NULL ||

			     test_bit(Faulty, &mrdev->flags) ||

			     test_bit(In_sync, &mrdev->flags)) &&

			    (mreplace == NULL ||

			     test_bit(Faulty, &mreplace->flags))) {
@@ -2971,6 +2975,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr, 
				rcu_read_unlock();

				continue;

			}

			if (mreplace && test_bit(Faulty, &mreplace->flags))

				mreplace = NULL;

			/* Unless we are doing a full sync, or a replacement

			 * we only need to recover the block if it is set in

			 * the bitmap

drivers/md/raid5.c

+2 −1
Original line number Diff line number Diff line
@@ -3080,7 +3080,8 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh, 
			struct md_rdev *rdev;

			rcu_read_lock();

			rdev = rcu_dereference(conf->disks[i].rdev);

			if (rdev && test_bit(In_sync, &rdev->flags))

			if (rdev && test_bit(In_sync, &rdev->flags) &&

			    !test_bit(Faulty, &rdev->flags))

				atomic_inc(&rdev->nr_pending);

			else

				rdev = NULL;