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Commit ba22dcbf authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: improvements to raid5 handling of read errors 



Two refinements to the 'attempt-overwrite-on-read-error' mechanism.
1/ If the array is read-only, don't attempt an over-write.
2/ If there are more than max_nr_stripes read errors on a device with
   no success, fail the drive.  This will make sure a dead
   drive will be eventually kicked even when we aren't trying
   to rewrite (which would normally kick a dead drive more quickly.

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 007583c9

drivers/md/md.c

+1 −0
Original line number Diff line number Diff line
@@ -1582,6 +1582,7 @@ static mdk_rdev_t *md_import_device(dev_t newdev, int super_format, int super_mi 
	rdev->in_sync = 0;

	rdev->data_offset = 0;

	atomic_set(&rdev->nr_pending, 0);

	atomic_set(&rdev->read_errors, 0);



	size = rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;

	if (!size) {

drivers/md/raid5.c

+17 −8
Original line number Diff line number Diff line
@@ -420,21 +420,29 @@ static int raid5_end_read_request(struct bio * bi, unsigned int bytes_done, 
			clear_bit(R5_ReadError, &sh->dev[i].flags);

			clear_bit(R5_ReWrite, &sh->dev[i].flags);

		}

		if (atomic_read(&conf->disks[i].rdev->read_errors))

			atomic_set(&conf->disks[i].rdev->read_errors, 0);

	} else {

		int retry = 0;

		clear_bit(R5_UPTODATE, &sh->dev[i].flags);

		if (conf->mddev->degraded) {

		atomic_inc(&conf->disks[i].rdev->read_errors);

		if (conf->mddev->degraded)

			printk("R5: read error not correctable.\n");

			clear_bit(R5_ReadError, &sh->dev[i].flags);

			clear_bit(R5_ReWrite, &sh->dev[i].flags);

			md_error(conf->mddev, conf->disks[i].rdev);

		} else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {

		else if (test_bit(R5_ReWrite, &sh->dev[i].flags))

			/* Oh, no!!! */

			printk("R5: read error NOT corrected!!\n");

		else if (atomic_read(&conf->disks[i].rdev->read_errors)

			 > conf->max_nr_stripes)

			printk("raid5: Too many read errors, failing device.\n");

		else

			retry = 1;

		if (retry)

			set_bit(R5_ReadError, &sh->dev[i].flags);

		else {

			clear_bit(R5_ReadError, &sh->dev[i].flags);

			clear_bit(R5_ReWrite, &sh->dev[i].flags);

			md_error(conf->mddev, conf->disks[i].rdev);

		} else

			set_bit(R5_ReadError, &sh->dev[i].flags);

		}

	}

	rdev_dec_pending(conf->disks[i].rdev, conf->mddev);

#if 0
@@ -1328,7 +1336,8 @@ static void handle_stripe(struct stripe_head *sh) 
	/* If the failed drive is just a ReadError, then we might need to progress

	 * the repair/check process

	 */

	if (failed == 1 && test_bit(R5_ReadError, &sh->dev[failed_num].flags)

	if (failed == 1 && ! conf->mddev->ro &&

	    test_bit(R5_ReadError, &sh->dev[failed_num].flags)

	    && !test_bit(R5_LOCKED, &sh->dev[failed_num].flags)

	    && test_bit(R5_UPTODATE, &sh->dev[failed_num].flags)

		) {

include/linux/raid/md_k.h

+3 −0
Original line number Diff line number Diff line
@@ -134,6 +134,9 @@ struct mdk_rdev_s 
					 * only maintained for arrays that

					 * support hot removal

					 */

	atomic_t	read_errors;	/* number of consecutive read errors that

					 * we have tried to ignore.

					 */

};



typedef struct mdk_personality_s mdk_personality_t;