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dm: Forbid requeue of writes to zones

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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: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Damien Le Moal 2021-05-26 06:24:58 +09:00 committed by Mike Snitzer
parent 912e887505
commit bf14e2b250
3 changed files with 41 additions and 6 deletions

17
drivers/md/dm-zone.c
View File

@ -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))

25
drivers/md/dm.c
View File

@ -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);
@ -947,7 +952,15 @@ static void clone_endio(struct bio *bio)
int r = endio(tio->ti, bio, &error);
switch (r) {
case DM_ENDIO_REQUEUE:
error = BLK_STS_DM_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:
break;

5
drivers/md/dm.h
View File

@ -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
/*-----------------------------------------------------------------