Commit bf14e2b2 authored by Damien Le Moal's avatar Damien Le Moal Committed by Mike Snitzer
Browse files

dm: Forbid requeue of writes to zones 



A target map method requesting the requeue of a bio with
DM_MAPIO_REQUEUE or completing it with DM_ENDIO_REQUEUE can cause
unaligned write errors if the bio is a write operation targeting a
sequential zone. If a zoned target request such a requeue, warn about
it and kill the IO.

The function dm_is_zone_write() is introduced to detect write operations
to zoned targets.

This change does not affect the target drivers supporting zoned devices
and exposing a zoned device, namely dm-crypt, dm-linear and dm-flakey as
none of these targets ever request a requeue.

Signed-off-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarHimanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 912e8875

drivers/md/dm-zone.c

+17 −0
Original line number Diff line number Diff line
@@ -104,6 +104,23 @@ int dm_report_zones(struct block_device *bdev, sector_t start, sector_t sector, 
}

EXPORT_SYMBOL_GPL(dm_report_zones);



bool dm_is_zone_write(struct mapped_device *md, struct bio *bio)

{

	struct request_queue *q = md->queue;



	if (!blk_queue_is_zoned(q))

		return false;



	switch (bio_op(bio)) {

	case REQ_OP_WRITE_ZEROES:

	case REQ_OP_WRITE_SAME:

	case REQ_OP_WRITE:

		return !op_is_flush(bio->bi_opf) && bio_sectors(bio);

	default:

		return false;

	}

}



void dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q)

{

	if (!blk_queue_is_zoned(q))

drivers/md/dm.c

+19 −6
Original line number Diff line number Diff line
@@ -841,22 +841,27 @@ static void dec_pending(struct dm_io *io, blk_status_t error) 
	}



	if (atomic_dec_and_test(&io->io_count)) {

		bio = io->orig_bio;

		if (io->status == BLK_STS_DM_REQUEUE) {

			/*

			 * Target requested pushing back the I/O.

			 */

			spin_lock_irqsave(&md->deferred_lock, flags);

			if (__noflush_suspending(md))

			if (__noflush_suspending(md) &&

			    !WARN_ON_ONCE(dm_is_zone_write(md, bio))) {

				/* NOTE early return due to BLK_STS_DM_REQUEUE below */

				bio_list_add_head(&md->deferred, io->orig_bio);

			else

				/* noflush suspend was interrupted. */

				bio_list_add_head(&md->deferred, bio);

			} else {

				/*

				 * noflush suspend was interrupted or this is

				 * a write to a zoned target.

				 */

				io->status = BLK_STS_IOERR;

			}

			spin_unlock_irqrestore(&md->deferred_lock, flags);

		}



		io_error = io->status;

		bio = io->orig_bio;

		end_io_acct(io);

		free_io(md, io);
@@ -947,6 +952,14 @@ static void clone_endio(struct bio *bio) 
		int r = endio(tio->ti, bio, &error);

		switch (r) {

		case DM_ENDIO_REQUEUE:

			/*

			 * Requeuing writes to a sequential zone of a zoned

			 * target will break the sequential write pattern:

			 * fail such IO.

			 */

			if (WARN_ON_ONCE(dm_is_zone_write(md, bio)))

				error = BLK_STS_IOERR;

			else

				error = BLK_STS_DM_REQUEUE;

			fallthrough;

		case DM_ENDIO_DONE:

drivers/md/dm.h

+5 −0
Original line number Diff line number Diff line
@@ -107,8 +107,13 @@ void dm_set_zones_restrictions(struct dm_table *t, struct request_queue *q); 
#ifdef CONFIG_BLK_DEV_ZONED

int dm_blk_report_zones(struct gendisk *disk, sector_t sector,

			unsigned int nr_zones, report_zones_cb cb, void *data);

bool dm_is_zone_write(struct mapped_device *md, struct bio *bio);

#else

#define dm_blk_report_zones	NULL

static inline bool dm_is_zone_write(struct mapped_device *md, struct bio *bio)

{

	return false;

}

#endif



/*-----------------------------------------------------------------