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Commit 707a6a42 authored by NeilBrown's avatar NeilBrown Committed by Shaohua Li
Browse files

md/raid1: add rcu protection to rdev in fix_read_error 



Since remove_and_add_spares() was added to hot_remove_disk() it has
been possible for an rdev to be hot-removed while fix_read_error()
was running, so we need to be more careful, and take a reference to
the rdev while performing IO.

Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 854abd75

drivers/md/raid1.c

+32 −20
Original line number Diff line number Diff line
@@ -2056,29 +2056,30 @@ static void fix_read_error(struct r1conf *conf, int read_disk, 
			s = PAGE_SIZE >> 9;



		do {

			/* Note: no rcu protection needed here

			 * as this is synchronous in the raid1d thread

			 * which is the thread that might remove

			 * a device.  If raid1d ever becomes multi-threaded....

			 */

			sector_t first_bad;

			int bad_sectors;



			rdev = conf->mirrors[d].rdev;

			rcu_read_lock();

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

			if (rdev &&

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

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

			      rdev->recovery_offset >= sect + s)) &&

			    is_badblock(rdev, sect, s,

					&first_bad, &bad_sectors) == 0 &&

			    sync_page_io(rdev, sect, s<<9,

					&first_bad, &bad_sectors) == 0) {

				atomic_inc(&rdev->nr_pending);

				rcu_read_unlock();

				if (sync_page_io(rdev, sect, s<<9,

						 conf->tmppage, READ, false))

					success = 1;

			else {

				rdev_dec_pending(rdev, mddev);

				if (success)

					break;

			} else

				rcu_read_unlock();

			d++;

			if (d == conf->raid_disks * 2)

				d = 0;

			}

		} while (!success && d != read_disk);



		if (!success) {
@@ -2094,11 +2095,17 @@ static void fix_read_error(struct r1conf *conf, int read_disk, 
			if (d==0)

				d = conf->raid_disks * 2;

			d--;

			rdev = conf->mirrors[d].rdev;

			rcu_read_lock();

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

			if (rdev &&

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

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

				atomic_inc(&rdev->nr_pending);

				rcu_read_unlock();

				r1_sync_page_io(rdev, sect, s,

						conf->tmppage, WRITE);

				rdev_dec_pending(rdev, mddev);

			} else

				rcu_read_unlock();

		}

		d = start;

		while (d != read_disk) {
@@ -2106,9 +2113,12 @@ static void fix_read_error(struct r1conf *conf, int read_disk, 
			if (d==0)

				d = conf->raid_disks * 2;

			d--;

			rdev = conf->mirrors[d].rdev;

			rcu_read_lock();

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

			if (rdev &&

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

				atomic_inc(&rdev->nr_pending);

				rcu_read_unlock();

				if (r1_sync_page_io(rdev, sect, s,

						    conf->tmppage, READ)) {

					atomic_add(s, &rdev->corrected_errors);
@@ -2120,7 +2130,9 @@ static void fix_read_error(struct r1conf *conf, int read_disk, 
								    rdev->data_offset),

					       bdevname(rdev->bdev, b));

				}

			}

				rdev_dec_pending(rdev, mddev);

			} else

				rcu_read_unlock();

		}

		sectors -= s;

		sect += s;