Commit 64a742bc authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: fix raid10 recovery problem. 



There are two errors that can lead to recovery problems with raid10
when used in 'far' more (not the default).

Due to a '>' instead of '>=' the wrong block is located which would result in
garbage being written to some random location, quite possible outside the
range of the device, causing the newly reconstructed device to fail.

The device size calculation had some rounding errors (it didn't round when it
should) and so recovery would go a few blocks too far which would again cause
a write to a random block address and probably a device error.

The code for working with device sizes was fairly confused and spread out, so
this has been tided up a bit.

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5a243e0e

drivers/md/raid10.c

+20 −18
Original line number Diff line number Diff line
@@ -429,7 +429,7 @@ static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev) 
		if (dev < 0)

			dev += conf->raid_disks;

	} else {

		while (sector > conf->stride) {

		while (sector >= conf->stride) {

			sector -= conf->stride;

			if (dev < conf->near_copies)

				dev += conf->raid_disks - conf->near_copies;
@@ -1801,6 +1801,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i 
						for (k=0; k<conf->copies; k++)

							if (r10_bio->devs[k].devnum == i)

								break;

						BUG_ON(k == conf->copies);

						bio = r10_bio->devs[1].bio;

						bio->bi_next = biolist;

						biolist = bio;
@@ -2021,19 +2022,30 @@ static int run(mddev_t *mddev) 
	if (!conf->tmppage)

		goto out_free_conf;



	conf->mddev = mddev;

	conf->raid_disks = mddev->raid_disks;

	conf->near_copies = nc;

	conf->far_copies = fc;

	conf->copies = nc*fc;

	conf->far_offset = fo;

	conf->chunk_mask = (sector_t)(mddev->chunk_size>>9)-1;

	conf->chunk_shift = ffz(~mddev->chunk_size) - 9;

	size = mddev->size >> (conf->chunk_shift-1);

	sector_div(size, fc);

	size = size * conf->raid_disks;

	sector_div(size, nc);

	/* 'size' is now the number of chunks in the array */

	/* calculate "used chunks per device" in 'stride' */

	stride = size * conf->copies;

	sector_div(stride, conf->raid_disks);

	mddev->size = stride  << (conf->chunk_shift-1);



	if (fo)

		conf->stride = 1 << conf->chunk_shift;

	else {

		stride = mddev->size >> (conf->chunk_shift-1);

		stride = 1;

	else

		sector_div(stride, fc);

	conf->stride = stride << conf->chunk_shift;

	}



	conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,

						r10bio_pool_free, conf);

	if (!conf->r10bio_pool) {
@@ -2063,8 +2075,6 @@ static int run(mddev_t *mddev) 


		disk->head_position = 0;

	}

	conf->raid_disks = mddev->raid_disks;

	conf->mddev = mddev;

	spin_lock_init(&conf->device_lock);

	INIT_LIST_HEAD(&conf->retry_list);
@@ -2106,16 +2116,8 @@ static int run(mddev_t *mddev) 
	/*

	 * Ok, everything is just fine now

	 */

	if (conf->far_offset) {

		size = mddev->size >> (conf->chunk_shift-1);

		size *= conf->raid_disks;

		size <<= conf->chunk_shift;

		sector_div(size, conf->far_copies);

	} else

		size = conf->stride * conf->raid_disks;

	sector_div(size, conf->near_copies);

	mddev->array_size = size/2;

	mddev->resync_max_sectors = size;

	mddev->array_size = size << (conf->chunk_shift-1);

	mddev->resync_max_sectors = size << conf->chunk_shift;



	mddev->queue->unplug_fn = raid10_unplug;

	mddev->queue->issue_flush_fn = raid10_issue_flush;

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