dm: support bio polling (b99fdcdc) · Commits · EulixOS / Software / Kernel

drivers/md/dm-core.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -235,6 +235,8 @@ struct dm_io {
		bool start_io_acct:1;
		int was_accounted;
		unsigned long start_time;
		void *data;
		struct hlist_node node;
		spinlock_t endio_lock;
		struct dm_stats_aux stats_aux;
		/* last member of dm_target_io is 'struct bio' */

drivers/md/dm-table.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -1481,6 +1481,14 @@ struct dm_target dm_table_find_target(struct dm_table t, sector_t sector)
		return &t->targets[(KEYS_PER_NODE * n) + k];
		}

		static int device_not_poll_capable(struct dm_target ti, struct dm_dev dev,
		sector_t start, sector_t len, void *data)
		{
		struct request_queue *q = bdev_get_queue(dev->bdev);

		return !test_bit(QUEUE_FLAG_POLL, &q->queue_flags);
		}

		/*
		* type->iterate_devices() should be called when the sanity check needs to
		* iterate and check all underlying data devices. iterate_devices() will
		@@ -1531,6 +1539,11 @@ static int count_device(struct dm_target ti, struct dm_dev dev,
		return 0;
		}

		static int dm_table_supports_poll(struct dm_table *t)
		{
		return !dm_table_any_dev_attr(t, device_not_poll_capable, NULL);
		}

		/*
		* Check whether a table has no data devices attached using each
		* target's iterate_devices method.
		@@ -2067,6 +2080,20 @@ int dm_table_set_restrictions(struct dm_table t, struct request_queue q,
		dm_update_crypto_profile(q, t);
		disk_update_readahead(t->md->disk);

		/*
		* Check for request-based device is left to
		* dm_mq_init_request_queue()->blk_mq_init_allocated_queue().
		*
		* For bio-based device, only set QUEUE_FLAG_POLL when all
		* underlying devices supporting polling.
		*/
		if (__table_type_bio_based(t->type)) {
		if (dm_table_supports_poll(t))
		blk_queue_flag_set(QUEUE_FLAG_POLL, q);
		else
		blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
		}

		return 0;
		}

drivers/md/dm.c

+140 −3

Original line number	Diff line number	Diff line
		@@ -40,6 +40,13 @@
		#define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
		#define DM_COOKIE_LENGTH 24

		/*
		* For REQ_POLLED fs bio, this flag is set if we link mapped underlying
		* dm_io into one list, and reuse bio->bi_private as the list head. Before
		* ending this fs bio, we will recover its ->bi_private.
		*/
		#define REQ_DM_POLL_LIST REQ_DRV

		static const char *_name = DM_NAME;

		static unsigned int major = 0;
		@@ -73,6 +80,7 @@ struct clone_info {
		struct dm_io *io;
		sector_t sector;
		unsigned sector_count;
		bool submit_as_polled;
		};

		#define DM_TARGET_IO_BIO_OFFSET (offsetof(struct dm_target_io, clone))
		@@ -599,6 +607,9 @@ static struct bio alloc_tio(struct clone_info ci, struct dm_target *ti,
		if (!clone)
		return NULL;

		/* REQ_DM_POLL_LIST shouldn't be inherited */
		clone->bi_opf &= ~REQ_DM_POLL_LIST;

		tio = clone_to_tio(clone);
		tio->inside_dm_io = false;
		}
		@@ -888,8 +899,15 @@ void dm_io_dec_pending(struct dm_io *io, blk_status_t error)
		if (unlikely(wq_has_sleeper(&md->wait)))
		wake_up(&md->wait);

		if (io_error == BLK_STS_DM_REQUEUE)
		if (io_error == BLK_STS_DM_REQUEUE) {
		/*
		* Upper layer won't help us poll split bio, io->orig_bio
		* may only reflect a subset of the pre-split original,
		* so clear REQ_POLLED in case of requeue
		*/
		bio->bi_opf &= ~REQ_POLLED;
		return;
		}

		if (bio_is_flush_with_data(bio)) {
		/*
		@@ -1440,6 +1458,47 @@ static bool __process_abnormal_io(struct clone_info ci, struct dm_target ti,
		return true;
		}

		/*
		* Reuse ->bi_private as hlist head for storing all dm_io instances
		* associated with this bio, and this bio's bi_private needs to be
		* stored in dm_io->data before the reuse.
		*
		* bio->bi_private is owned by fs or upper layer, so block layer won't
		* touch it after splitting. Meantime it won't be changed by anyone after
		* bio is submitted. So this reuse is safe.
		*/
		static inline struct hlist_head dm_get_bio_hlist_head(struct bio bio)
		{
		return (struct hlist_head *)&bio->bi_private;
		}

		static void dm_queue_poll_io(struct bio bio, struct dm_io io)
		{
		struct hlist_head *head = dm_get_bio_hlist_head(bio);

		if (!(bio->bi_opf & REQ_DM_POLL_LIST)) {
		bio->bi_opf \|= REQ_DM_POLL_LIST;
		/*
		* Save .bi_private into dm_io, so that we can reuse
		* .bi_private as hlist head for storing dm_io list
		*/
		io->data = bio->bi_private;

		INIT_HLIST_HEAD(head);

		/* tell block layer to poll for completion */
		bio->bi_cookie = ~BLK_QC_T_NONE;
		} else {
		/*
		* bio recursed due to split, reuse original poll list,
		* and save bio->bi_private too.
		*/
		io->data = hlist_entry(head->first, struct dm_io, node)->data;
		}

		hlist_add_head(&io->node, head);
		}

		/*
		* Select the correct strategy for processing a non-flush bio.
		*/
		@@ -1457,6 +1516,12 @@ static int __split_and_process_bio(struct clone_info *ci)
		if (__process_abnormal_io(ci, ti, &r))
		return r;

		/*
		* Only support bio polling for normal IO, and the target io is
		* exactly inside the dm_io instance (verified in dm_poll_dm_io)
		*/
		ci->submit_as_polled = ci->bio->bi_opf & REQ_POLLED;

		len = min_t(sector_t, max_io_len(ti, ci->sector), ci->sector_count);
		clone = alloc_tio(ci, ti, 0, &len, GFP_NOIO);
		__map_bio(clone);
		@@ -1473,6 +1538,7 @@ static void init_clone_info(struct clone_info ci, struct mapped_device md,
		ci->map = map;
		ci->io = alloc_io(md, bio);
		ci->bio = bio;
		ci->submit_as_polled = false;
		ci->sector = bio->bi_iter.bi_sector;
		ci->sector_count = bio_sectors(bio);

		@@ -1522,8 +1588,17 @@ static void dm_split_and_process_bio(struct mapped_device *md,
		if (ci.io->start_io_acct)
		dm_start_io_acct(ci.io, NULL);

		/* drop the extra reference count */
		/*
		* Drop the extra reference count for non-POLLED bio, and hold one
		* reference for POLLED bio, which will be released in dm_poll_bio
		*
		* Add every dm_io instance into the hlist_head which is stored in
		* bio->bi_private, so that dm_poll_bio can poll them all.
		*/
		if (error \|\| !ci.submit_as_polled)
		dm_io_dec_pending(ci.io, errno_to_blk_status(error));
		else
		dm_queue_poll_io(bio, ci.io);
		}

		static void dm_submit_bio(struct bio *bio)
		@@ -1558,6 +1633,67 @@ static void dm_submit_bio(struct bio *bio)
		dm_put_live_table(md, srcu_idx);
		}

		static bool dm_poll_dm_io(struct dm_io io, struct io_comp_batch iob,
		unsigned int flags)
		{
		WARN_ON_ONCE(!io->tio.inside_dm_io);

		/* don't poll if the mapped io is done */
		if (atomic_read(&io->io_count) > 1)
		bio_poll(&io->tio.clone, iob, flags);

		/* bio_poll holds the last reference */
		return atomic_read(&io->io_count) == 1;
		}

		static int dm_poll_bio(struct bio bio, struct io_comp_batch iob,
		unsigned int flags)
		{
		struct hlist_head *head = dm_get_bio_hlist_head(bio);
		struct hlist_head tmp = HLIST_HEAD_INIT;
		struct hlist_node *next;
		struct dm_io *io;

		/* Only poll normal bio which was marked as REQ_DM_POLL_LIST */
		if (!(bio->bi_opf & REQ_DM_POLL_LIST))
		return 0;

		WARN_ON_ONCE(hlist_empty(head));

		hlist_move_list(head, &tmp);

		/*
		* Restore .bi_private before possibly completing dm_io.
		*
		* bio_poll() is only possible once @bio has been completely
		* submitted via submit_bio_noacct()'s depth-first submission.
		* So there is no dm_queue_poll_io() race associated with
		* clearing REQ_DM_POLL_LIST here.
		*/
		bio->bi_opf &= ~REQ_DM_POLL_LIST;
		bio->bi_private = hlist_entry(tmp.first, struct dm_io, node)->data;

		hlist_for_each_entry_safe(io, next, &tmp, node) {
		if (dm_poll_dm_io(io, iob, flags)) {
		hlist_del_init(&io->node);
		/*
		* clone_endio() has already occurred, so passing
		* error as 0 here doesn't override io->status
		*/
		dm_io_dec_pending(io, 0);
		}
		}

		/* Not done? */
		if (!hlist_empty(&tmp)) {
		bio->bi_opf \|= REQ_DM_POLL_LIST;
		/* Reset bio->bi_private to dm_io list head */
		hlist_move_list(&tmp, head);
		return 0;
		}
		return 1;
		}

		/*-----------------------------------------------------------------
		* An IDR is used to keep track of allocated minor numbers.
		---------------------------------------------------------------/
		@@ -2983,6 +3119,7 @@ static const struct pr_ops dm_pr_ops = {

		static const struct block_device_operations dm_blk_dops = {
		.submit_bio = dm_submit_bio,
		.poll_bio = dm_poll_bio,
		.open = dm_blk_open,
		.release = dm_blk_close,
		.ioctl = dm_blk_ioctl,