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authorMike Snitzer2017-12-09 21:16:42 +0100
committerMike Snitzer2017-12-20 16:51:11 +0100
commit978e51ba38e00e9da09b3ef9ed8c94af7b55a1eb (patch)
tree6d8b8907aff2af4d02032b616d28bbc4c50192f2 /drivers/md/dm.c
parentdm: introduce DM_TYPE_NVME_BIO_BASED (diff)
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dm: optimize bio-based NVMe IO submission
Upper level bio-based drivers that stack immediately ontop of NVMe can leverage direct_make_request(). In addition DM's NVMe bio-based will initially only ever have one NVMe device that it submits IO to at a time. There is no splitting needed. Enhance DM core so that DM_TYPE_NVME_BIO_BASED's IO submission takes advantage of both of these characteristics. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c154
1 files changed, 120 insertions, 34 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a1bd7a6ff522..73d7f316ac1d 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -532,7 +532,9 @@ out:
return r;
}
-static struct dm_io *alloc_io(struct mapped_device *md)
+static void start_io_acct(struct dm_io *io);
+
+static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
{
struct dm_io *io;
struct dm_target_io *tio;
@@ -548,6 +550,13 @@ static struct dm_io *alloc_io(struct mapped_device *md)
io = container_of(tio, struct dm_io, tio);
io->magic = DM_IO_MAGIC;
+ io->status = 0;
+ atomic_set(&io->io_count, 1);
+ io->orig_bio = bio;
+ io->md = md;
+ spin_lock_init(&io->endio_lock);
+
+ start_io_acct(io);
return io;
}
@@ -924,7 +933,7 @@ static void clone_endio(struct bio *bio)
struct mapped_device *md = tio->io->md;
dm_endio_fn endio = tio->ti->type->end_io;
- if (unlikely(error == BLK_STS_TARGET)) {
+ if (unlikely(error == BLK_STS_TARGET) && md->type != DM_TYPE_NVME_BIO_BASED) {
if (bio_op(bio) == REQ_OP_WRITE_SAME &&
!bio->bi_disk->queue->limits.max_write_same_sectors)
disable_write_same(md);
@@ -1191,13 +1200,15 @@ void dm_remap_zone_report(struct dm_target *ti, struct bio *bio, sector_t start)
}
EXPORT_SYMBOL_GPL(dm_remap_zone_report);
-static void __map_bio(struct dm_target_io *tio)
+static blk_qc_t __map_bio(struct dm_target_io *tio)
{
int r;
sector_t sector;
struct bio *clone = &tio->clone;
struct dm_io *io = tio->io;
+ struct mapped_device *md = io->md;
struct dm_target *ti = tio->ti;
+ blk_qc_t ret = BLK_QC_T_NONE;
clone->bi_end_io = clone_endio;
@@ -1217,7 +1228,10 @@ static void __map_bio(struct dm_target_io *tio)
/* the bio has been remapped so dispatch it */
trace_block_bio_remap(clone->bi_disk->queue, clone,
bio_dev(io->orig_bio), sector);
- generic_make_request(clone);
+ if (md->type == DM_TYPE_NVME_BIO_BASED)
+ ret = direct_make_request(clone);
+ else
+ ret = generic_make_request(clone);
break;
case DM_MAPIO_KILL:
free_tio(tio);
@@ -1231,6 +1245,8 @@ static void __map_bio(struct dm_target_io *tio)
DMWARN("unimplemented target map return value: %d", r);
BUG();
}
+
+ return ret;
}
static void bio_setup_sector(struct bio *bio, sector_t sector, unsigned len)
@@ -1315,8 +1331,8 @@ static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
}
}
-static void __clone_and_map_simple_bio(struct clone_info *ci,
- struct dm_target_io *tio, unsigned *len)
+static blk_qc_t __clone_and_map_simple_bio(struct clone_info *ci,
+ struct dm_target_io *tio, unsigned *len)
{
struct bio *clone = &tio->clone;
@@ -1326,7 +1342,7 @@ static void __clone_and_map_simple_bio(struct clone_info *ci,
if (len)
bio_setup_sector(clone, ci->sector, *len);
- __map_bio(tio);
+ return __map_bio(tio);
}
static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
@@ -1340,7 +1356,7 @@ static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
while ((bio = bio_list_pop(&blist))) {
tio = container_of(bio, struct dm_target_io, clone);
- __clone_and_map_simple_bio(ci, tio, len);
+ (void) __clone_and_map_simple_bio(ci, tio, len);
}
}
@@ -1370,7 +1386,7 @@ static int __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
free_tio(tio);
return r;
}
- __map_bio(tio);
+ (void) __map_bio(tio);
return 0;
}
@@ -1482,30 +1498,30 @@ static int __split_and_process_non_flush(struct clone_info *ci)
return 0;
}
+static void init_clone_info(struct clone_info *ci, struct mapped_device *md,
+ struct dm_table *map, struct bio *bio)
+{
+ ci->map = map;
+ ci->io = alloc_io(md, bio);
+ ci->sector = bio->bi_iter.bi_sector;
+}
+
/*
* Entry point to split a bio into clones and submit them to the targets.
*/
-static void __split_and_process_bio(struct mapped_device *md,
- struct dm_table *map, struct bio *bio)
+static blk_qc_t __split_and_process_bio(struct mapped_device *md,
+ struct dm_table *map, struct bio *bio)
{
struct clone_info ci;
+ blk_qc_t ret = BLK_QC_T_NONE;
int error = 0;
if (unlikely(!map)) {
bio_io_error(bio);
- return;
+ return ret;
}
- ci.map = map;
- ci.io = alloc_io(md);
- ci.io->status = 0;
- atomic_set(&ci.io->io_count, 1);
- ci.io->orig_bio = bio;
- ci.io->md = md;
- spin_lock_init(&ci.io->endio_lock);
- ci.sector = bio->bi_iter.bi_sector;
-
- start_io_acct(ci.io);
+ init_clone_info(&ci, md, map, bio);
if (bio->bi_opf & REQ_PREFLUSH) {
ci.bio = &ci.io->md->flush_bio;
@@ -1538,7 +1554,7 @@ static void __split_and_process_bio(struct mapped_device *md,
ci.io->orig_bio = b;
bio_advance(bio, (bio_sectors(bio) - ci.sector_count) << 9);
bio_chain(b, bio);
- generic_make_request(bio);
+ ret = generic_make_request(bio);
break;
}
}
@@ -1546,15 +1562,63 @@ static void __split_and_process_bio(struct mapped_device *md,
/* drop the extra reference count */
dec_pending(ci.io, errno_to_blk_status(error));
+ return ret;
}
/*
- * The request function that remaps the bio to one target and
- * splits off any remainder.
+ * Optimized variant of __split_and_process_bio that leverages the
+ * fact that targets that use it do _not_ have a need to split bios.
*/
-static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
+static blk_qc_t __process_bio(struct mapped_device *md,
+ struct dm_table *map, struct bio *bio)
+{
+ struct clone_info ci;
+ blk_qc_t ret = BLK_QC_T_NONE;
+ int error = 0;
+
+ if (unlikely(!map)) {
+ bio_io_error(bio);
+ return ret;
+ }
+
+ init_clone_info(&ci, md, map, bio);
+
+ if (bio->bi_opf & REQ_PREFLUSH) {
+ ci.bio = &ci.io->md->flush_bio;
+ ci.sector_count = 0;
+ error = __send_empty_flush(&ci);
+ /* dec_pending submits any data associated with flush */
+ } else {
+ struct dm_target *ti = md->immutable_target;
+ struct dm_target_io *tio;
+
+ /*
+ * Defend against IO still getting in during teardown
+ * - as was seen for a time with nvme-fcloop
+ */
+ if (unlikely(WARN_ON_ONCE(!ti || !dm_target_is_valid(ti)))) {
+ error = -EIO;
+ goto out;
+ }
+
+ tio = alloc_tio(&ci, ti, 0, GFP_NOIO);
+ ci.bio = bio;
+ ci.sector_count = bio_sectors(bio);
+ ret = __clone_and_map_simple_bio(&ci, tio, NULL);
+ }
+out:
+ /* drop the extra reference count */
+ dec_pending(ci.io, errno_to_blk_status(error));
+ return ret;
+}
+
+typedef blk_qc_t (process_bio_fn)(struct mapped_device *, struct dm_table *, struct bio *);
+
+static blk_qc_t __dm_make_request(struct request_queue *q, struct bio *bio,
+ process_bio_fn process_bio)
{
struct mapped_device *md = q->queuedata;
+ blk_qc_t ret = BLK_QC_T_NONE;
int srcu_idx;
struct dm_table *map;
@@ -1568,12 +1632,27 @@ static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
queue_io(md, bio);
else
bio_io_error(bio);
- return BLK_QC_T_NONE;
+ return ret;
}
- __split_and_process_bio(md, map, bio);
+ ret = process_bio(md, map, bio);
+
dm_put_live_table(md, srcu_idx);
- return BLK_QC_T_NONE;
+ return ret;
+}
+
+/*
+ * The request function that remaps the bio to one target and
+ * splits off any remainder.
+ */
+static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
+{
+ return __dm_make_request(q, bio, __split_and_process_bio);
+}
+
+static blk_qc_t dm_make_request_nvme(struct request_queue *q, struct bio *bio)
+{
+ return __dm_make_request(q, bio, __process_bio);
}
static int dm_any_congested(void *congested_data, int bdi_bits)
@@ -1927,6 +2006,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
{
struct dm_table *old_map;
struct request_queue *q = md->queue;
+ bool request_based = dm_table_request_based(t);
sector_t size;
lockdep_assert_held(&md->suspend_lock);
@@ -1950,12 +2030,15 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
* This must be done before setting the queue restrictions,
* because request-based dm may be run just after the setting.
*/
- if (dm_table_request_based(t)) {
+ if (request_based)
dm_stop_queue(q);
+
+ if (request_based || md->type == DM_TYPE_NVME_BIO_BASED) {
/*
- * Leverage the fact that request-based DM targets are
- * immutable singletons and establish md->immutable_target
- * - used to optimize both dm_request_fn and dm_mq_queue_rq
+ * Leverage the fact that request-based DM targets and
+ * NVMe bio based targets are immutable singletons
+ * - used to optimize both dm_request_fn and dm_mq_queue_rq;
+ * and __process_bio.
*/
md->immutable_target = dm_table_get_immutable_target(t);
}
@@ -2073,10 +2156,13 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
break;
case DM_TYPE_BIO_BASED:
case DM_TYPE_DAX_BIO_BASED:
- case DM_TYPE_NVME_BIO_BASED:
dm_init_normal_md_queue(md);
blk_queue_make_request(md->queue, dm_make_request);
break;
+ case DM_TYPE_NVME_BIO_BASED:
+ dm_init_normal_md_queue(md);
+ blk_queue_make_request(md->queue, dm_make_request_nvme);
+ break;
case DM_TYPE_NONE:
WARN_ON_ONCE(true);
break;