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dm: respect REQ_NOWAIT flag in normal bios issued to DM

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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 a9ce385344 ("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: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mike Snitzer 2023-10-25 19:29:03 -04:00
parent 4a2fe29608
commit 6f25dd1c57
1 changed files with 29 additions and 11 deletions
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40
drivers/md/dm.c
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@ -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);
clone = alloc_tio(ci, ti, 0, &len, GFP_NOIO);
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);