Commit c916ca35 authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

md/raid1: Fix data corruption for degraded array with slow disk 



read_balance() will avoid reading from slow disks as much as possible,
however, if valid data only lands in slow disks, and a new normal disk
is still in recovery, unrecovered data can be read:

raid1_read_request
 read_balance
  raid1_should_read_first
  -> return false
  choose_best_rdev
  -> normal disk is not recovered, return -1
  choose_bb_rdev
  -> missing the checking of recovery, return the normal disk
 -> read unrecovered data

Root cause is that the checking of recovery is missing in
choose_bb_rdev(). Hence add such checking to fix the problem.

Also fix similar problem in choose_slow_rdev().

Cc: stable@vger.kernel.org
Fixes: 9f3ced79 ("md/raid1: factor out choose_bb_rdev() from read_balance()")
Fixes: dfa8ecd1 ("md/raid1: factor out choose_slow_rdev() from read_balance()")
Reported-and-tested-by: default avatarMateusz Jończyk <mat.jonczyk@o2.pl>
Closes: https://lore.kernel.org/all/9952f532-2554-44bf-b906-4880b2e88e3a@o2.pl/


Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240803091137.3197008-1-yukuai1@huaweicloud.com


Signed-off-by: default avatarSong Liu <song@kernel.org>
parent 7db40423

drivers/md/raid1.c

+10 −4
Original line number Diff line number Diff line
@@ -617,6 +617,12 @@ static int choose_first_rdev(struct r1conf *conf, struct r1bio *r1_bio, 
	return -1;

}



static bool rdev_in_recovery(struct md_rdev *rdev, struct r1bio *r1_bio)

{

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

	       rdev->recovery_offset < r1_bio->sector + r1_bio->sectors;

}



static int choose_bb_rdev(struct r1conf *conf, struct r1bio *r1_bio,

			  int *max_sectors)

{
@@ -635,6 +641,7 @@ static int choose_bb_rdev(struct r1conf *conf, struct r1bio *r1_bio, 


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

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

		    rdev_in_recovery(rdev, r1_bio) ||

		    test_bit(WriteMostly, &rdev->flags))

			continue;
@@ -673,7 +680,8 @@ static int choose_slow_rdev(struct r1conf *conf, struct r1bio *r1_bio, 


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

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

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

		    !test_bit(WriteMostly, &rdev->flags) ||

		    rdev_in_recovery(rdev, r1_bio))

			continue;



		/* there are no bad blocks, we can use this disk */
@@ -733,9 +741,7 @@ static bool rdev_readable(struct md_rdev *rdev, struct r1bio *r1_bio) 
	if (!rdev || test_bit(Faulty, &rdev->flags))

		return false;



	/* still in recovery */

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

	    rdev->recovery_offset < r1_bio->sector + r1_bio->sectors)

	if (rdev_in_recovery(rdev, r1_bio))

		return false;



	/* don't read from slow disk unless have to */