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Commit 73ac105b authored by Tang Junhui's avatar Tang Junhui Committed by Jens Axboe
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bcache: fix for data collapse after re-attaching an attached device 



back-end device sdm has already attached a cache_set with ID
f67ebe1f-f8bc-4d73-bfe5-9dc88607f119, then try to attach with
another cache set, and it returns with an error:
[root]# cd /sys/block/sdm/bcache
[root]# echo 5ccd0a63-148e-48b8-afa2-aca9cbd6279f > attach
-bash: echo: write error: Invalid argument

After that, execute a command to modify the label of bcache
device:
[root]# echo data_disk1 > label

Then we reboot the system, when the system power on, the back-end
device can not attach to cache_set, a messages show in the log:
Feb  5 12:05:52 ceph152 kernel: [922385.508498] bcache:
bch_cached_dev_attach() couldn't find uuid for sdm in set

In sysfs_attach(), dc->sb.set_uuid was assigned to the value
which input through sysfs, no matter whether it is success
or not in bch_cached_dev_attach(). For example, If the back-end
device has already attached to an cache set, bch_cached_dev_attach()
would fail, but dc->sb.set_uuid was changed. Then modify the
label of bcache device, it will call bch_write_bdev_super(),
which would write the dc->sb.set_uuid to the super block, so we
record a wrong cache set ID in the super block, after the system
reboot, the cache set couldn't find the uuid of the back-end
device, so the bcache device couldn't exist and use any more.

In this patch, we don't assigned cache set ID to dc->sb.set_uuid
in sysfs_attach() directly, but input it into bch_cached_dev_attach(),
and assigned dc->sb.set_uuid to the cache set ID after the back-end
device attached to the cache set successful.

Signed-off-by: default avatarTang Junhui <tang.junhui@zte.com.cn>
Reviewed-by: default avatarMichael Lyle <mlyle@lyle.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7f4fc93d

drivers/md/bcache/bcache.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -924,7 +924,7 @@ void bcache_write_super(struct cache_set *); 




int bch_flash_dev_create(struct cache_set *c, uint64_t size);

int bch_flash_dev_create(struct cache_set *c, uint64_t size);





int bch_cached_dev_attach(struct cached_dev *, struct cache_set *);

int bch_cached_dev_attach(struct cached_dev *, struct cache_set *, uint8_t *);

void bch_cached_dev_detach(struct cached_dev *);

void bch_cached_dev_detach(struct cached_dev *);

void bch_cached_dev_run(struct cached_dev *);

void bch_cached_dev_run(struct cached_dev *);

void bcache_device_stop(struct bcache_device *);

void bcache_device_stop(struct bcache_device *);

drivers/md/bcache/super.c

+6 −4
Original line number Original line Diff line number Diff line
@@ -957,7 +957,8 @@ void bch_cached_dev_detach(struct cached_dev *dc) 
	cached_dev_put(dc);

	cached_dev_put(dc);

}

}





int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c)

int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,

			  uint8_t *set_uuid)

{

{

	uint32_t rtime = cpu_to_le32(get_seconds());

	uint32_t rtime = cpu_to_le32(get_seconds());

	struct uuid_entry *u;

	struct uuid_entry *u;
@@ -965,7 +966,8 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c) 




	bdevname(dc->bdev, buf);

	bdevname(dc->bdev, buf);





	if (memcmp(dc->sb.set_uuid, c->sb.set_uuid, 16))

	if ((set_uuid && memcmp(set_uuid, c->sb.set_uuid, 16)) ||

	    (!set_uuid && memcmp(dc->sb.set_uuid, c->sb.set_uuid, 16)))

		return -ENOENT;

		return -ENOENT;





	if (dc->disk.c) {

	if (dc->disk.c) {
@@ -1194,7 +1196,7 @@ static void register_bdev(struct cache_sb *sb, struct page *sb_page, 




	list_add(&dc->list, &uncached_devices);

	list_add(&dc->list, &uncached_devices);

	list_for_each_entry(c, &bch_cache_sets, list)

	list_for_each_entry(c, &bch_cache_sets, list)

		bch_cached_dev_attach(dc, c);

		bch_cached_dev_attach(dc, c, NULL);





	if (BDEV_STATE(&dc->sb) == BDEV_STATE_NONE ||

	if (BDEV_STATE(&dc->sb) == BDEV_STATE_NONE ||

	    BDEV_STATE(&dc->sb) == BDEV_STATE_STALE)

	    BDEV_STATE(&dc->sb) == BDEV_STATE_STALE)
@@ -1716,7 +1718,7 @@ static void run_cache_set(struct cache_set *c) 
	bcache_write_super(c);

	bcache_write_super(c);





	list_for_each_entry_safe(dc, t, &uncached_devices, list)

	list_for_each_entry_safe(dc, t, &uncached_devices, list)

		bch_cached_dev_attach(dc, c);

		bch_cached_dev_attach(dc, c, NULL);





	flash_devs_run(c);

	flash_devs_run(c);

drivers/md/bcache/sysfs.c

+4 −2
Original line number Original line Diff line number Diff line
@@ -272,12 +272,14 @@ STORE(__cached_dev) 
	}

	}





	if (attr == &sysfs_attach) {

	if (attr == &sysfs_attach) {

		if (bch_parse_uuid(buf, dc->sb.set_uuid) < 16)

		uint8_t		set_uuid[16];



		if (bch_parse_uuid(buf, set_uuid) < 16)

			return -EINVAL;

			return -EINVAL;





		v = -ENOENT;

		v = -ENOENT;

		list_for_each_entry(c, &bch_cache_sets, list) {

		list_for_each_entry(c, &bch_cache_sets, list) {

			v = bch_cached_dev_attach(dc, c);

			v = bch_cached_dev_attach(dc, c, set_uuid);

			if (!v)

			if (!v)

				return size;

				return size;

		}

		}