Commit 6f25dd1c authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: respect REQ_NOWAIT flag in normal bios issued to DM 



Update DM core's normal IO submission to allocate required memory
using GFP_NOWAIT if REQ_NOWAIT is set.

Tested with simple test provided in commit a9ce3853 ("dm: don't
attempt to queue IO under RCU protection") that was enhanced to check
error codes.  Also tested using fio's pvsync2 with nowait=1.

But testing with induced GFP_NOWAIT allocation failures wasn't
performed (yet).

Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent 4a2fe296

drivers/md/dm.c

+29 −11
Original line number Diff line number Diff line
@@ -570,13 +570,15 @@ static void dm_end_io_acct(struct dm_io *io) 
	dm_io_acct(io, true);

}



static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)

static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio, gfp_t gfp_mask)

{

	struct dm_io *io;

	struct dm_target_io *tio;

	struct bio *clone;



	clone = bio_alloc_clone(NULL, bio, GFP_NOIO, &md->mempools->io_bs);

	clone = bio_alloc_clone(NULL, bio, gfp_mask, &md->mempools->io_bs);

	if (unlikely(!clone))

		return NULL;

	tio = clone_to_tio(clone);

	tio->flags = 0;

	dm_tio_set_flag(tio, DM_TIO_INSIDE_DM_IO);
@@ -1714,10 +1716,6 @@ static blk_status_t __split_and_process_bio(struct clone_info *ci) 
	if (unlikely(!ti))

		return BLK_STS_IOERR;



	if (unlikely((ci->bio->bi_opf & REQ_NOWAIT) != 0) &&

	    unlikely(!dm_target_supports_nowait(ti->type)))

		return BLK_STS_NOTSUPP;



	if (unlikely(ci->is_abnormal_io))

		return __process_abnormal_io(ci, ti);
@@ -1729,7 +1727,17 @@ static blk_status_t __split_and_process_bio(struct clone_info *ci) 


	len = min_t(sector_t, max_io_len(ti, ci->sector), ci->sector_count);

	setup_split_accounting(ci, len);



	if (unlikely(ci->bio->bi_opf & REQ_NOWAIT)) {

		if (unlikely(!dm_target_supports_nowait(ti->type)))

			return BLK_STS_NOTSUPP;



		clone = alloc_tio(ci, ti, 0, &len, GFP_NOWAIT);

		if (unlikely(!clone))

			return BLK_STS_AGAIN;

	} else {

		clone = alloc_tio(ci, ti, 0, &len, GFP_NOIO);

	}

	__map_bio(clone);



	ci->sector += len;
@@ -1738,11 +1746,11 @@ static blk_status_t __split_and_process_bio(struct clone_info *ci) 
	return BLK_STS_OK;

}



static void init_clone_info(struct clone_info *ci, struct mapped_device *md,

static void init_clone_info(struct clone_info *ci, struct dm_io *io,

			    struct dm_table *map, struct bio *bio, bool is_abnormal)

{

	ci->map = map;

	ci->io = alloc_io(md, bio);

	ci->io = io;

	ci->bio = bio;

	ci->is_abnormal_io = is_abnormal;

	ci->submit_as_polled = false;
@@ -1777,8 +1785,18 @@ static void dm_split_and_process_bio(struct mapped_device *md, 
			return;

	}



	init_clone_info(&ci, md, map, bio, is_abnormal);

	io = ci.io;

	/* Only support nowait for normal IO */

	if (unlikely(bio->bi_opf & REQ_NOWAIT) && !is_abnormal) {

		io = alloc_io(md, bio, GFP_NOWAIT);

		if (unlikely(!io)) {

			/* Unable to do anything without dm_io. */

			bio_wouldblock_error(bio);

			return;

		}

	} else {

		io = alloc_io(md, bio, GFP_NOIO);

	}

	init_clone_info(&ci, io, map, bio, is_abnormal);



	if (bio->bi_opf & REQ_PREFLUSH) {

		__send_empty_flush(&ci);