1 files changed, 84 insertions, 57 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 64a1f306c9..23c32cd1f1 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -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);
@@ -724,7 +726,7 @@ static struct table_device *open_table_device(struct mapped_device *md,
 		dev_t dev, blk_mode_t mode)
 {
 	struct table_device *td;
-	struct block_device *bdev;
+	struct bdev_handle *bdev_handle;
 	u64 part_off;
 	int r;
 
@@ -733,9 +735,9 @@ static struct table_device *open_table_device(struct mapped_device *md,
 		return ERR_PTR(-ENOMEM);
 	refcount_set(&td->count, 1);
 
-	bdev = blkdev_get_by_dev(dev, mode, _dm_claim_ptr, NULL);
-	if (IS_ERR(bdev)) {
-		r = PTR_ERR(bdev);
+	bdev_handle = bdev_open_by_dev(dev, mode, _dm_claim_ptr, NULL);
+	if (IS_ERR(bdev_handle)) {
+		r = PTR_ERR(bdev_handle);
 		goto out_free_td;
 	}
 
@@ -745,20 +747,22 @@ static struct table_device *open_table_device(struct mapped_device *md,
 	 * called.
 	 */
 	if (md->disk->slave_dir) {
-		r = bd_link_disk_holder(bdev, md->disk);
+		r = bd_link_disk_holder(bdev_handle->bdev, md->disk);
 		if (r)
 			goto out_blkdev_put;
 	}
 
 	td->dm_dev.mode = mode;
-	td->dm_dev.bdev = bdev;
-	td->dm_dev.dax_dev = fs_dax_get_by_bdev(bdev, &part_off, NULL, NULL);
+	td->dm_dev.bdev = bdev_handle->bdev;
+	td->dm_dev.bdev_handle = bdev_handle;
+	td->dm_dev.dax_dev = fs_dax_get_by_bdev(bdev_handle->bdev, &part_off,
+						NULL, NULL);
 	format_dev_t(td->dm_dev.name, dev);
 	list_add(&td->list, &md->table_devices);
 	return td;
 
 out_blkdev_put:
-	blkdev_put(bdev, _dm_claim_ptr);
+	bdev_release(bdev_handle);
 out_free_td:
 	kfree(td);
 	return ERR_PTR(r);
@@ -771,7 +775,7 @@ static void close_table_device(struct table_device *td, struct mapped_device *md
 {
 	if (md->disk->slave_dir)
 		bd_unlink_disk_holder(td->dm_dev.bdev, md->disk);
-	blkdev_put(td->dm_dev.bdev, _dm_claim_ptr);
+	bdev_release(td->dm_dev.bdev_handle);
 	put_dax(td->dm_dev.dax_dev);
 	list_del(&td->list);
 	kfree(td);
@@ -1424,9 +1428,16 @@ static void __map_bio(struct bio *clone)
 		if (unlikely(dm_emulate_zone_append(md)))
 			r = dm_zone_map_bio(tio);
 		else
+			goto do_map;
+	} else {
+do_map:
+		if (likely(ti->type->map == linear_map))
+			r = linear_map(ti, clone);
+		else if (ti->type->map == stripe_map)
+			r = stripe_map(ti, clone);
+		else
 			r = ti->type->map(ti, clone);
-	} else
-		r = ti->type->map(ti, clone);
+	}
 
 	switch (r) {
 	case DM_MAPIO_SUBMITTED:
@@ -1471,15 +1482,15 @@ static void setup_split_accounting(struct clone_info *ci, unsigned int len)
 
 static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
 				struct dm_target *ti, unsigned int num_bios,
-				unsigned *len)
+				unsigned *len, gfp_t gfp_flag)
 {
 	struct bio *bio;
-	int try;
+	int try = (gfp_flag & GFP_NOWAIT) ? 0 : 1;
 
-	for (try = 0; try < 2; try++) {
+	for (; try < 2; try++) {
 		int bio_nr;
 
-		if (try)
+		if (try && num_bios > 1)
 			mutex_lock(&ci->io->md->table_devices_lock);
 		for (bio_nr = 0; bio_nr < num_bios; bio_nr++) {
 			bio = alloc_tio(ci, ti, bio_nr, len,
@@ -1489,7 +1500,7 @@ static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
 
 			bio_list_add(blist, bio);
 		}
-		if (try)
+		if (try && num_bios > 1)
 			mutex_unlock(&ci->io->md->table_devices_lock);
 		if (bio_nr == num_bios)
 			return;
@@ -1499,34 +1510,31 @@ static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
 	}
 }
 
-static int __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
-				 unsigned int num_bios, unsigned int *len)
+static unsigned int __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
+					  unsigned int num_bios, unsigned int *len,
+					  gfp_t gfp_flag)
 {
 	struct bio_list blist = BIO_EMPTY_LIST;
 	struct bio *clone;
 	unsigned int ret = 0;
 
-	switch (num_bios) {
-	case 0:
-		break;
-	case 1:
-		if (len)
-			setup_split_accounting(ci, *len);
-		clone = alloc_tio(ci, ti, 0, len, GFP_NOIO);
-		__map_bio(clone);
-		ret = 1;
-		break;
-	default:
-		if (len)
-			setup_split_accounting(ci, *len);
-		/* dm_accept_partial_bio() is not supported with shared tio->len_ptr */
-		alloc_multiple_bios(&blist, ci, ti, num_bios, len);
-		while ((clone = bio_list_pop(&blist))) {
+	if (WARN_ON_ONCE(num_bios == 0)) /* num_bios = 0 is a bug in caller */
+		return 0;
+
+	/* dm_accept_partial_bio() is not supported with shared tio->len_ptr */
+	if (len)
+		setup_split_accounting(ci, *len);
+
+	/*
+	 * Using alloc_multiple_bios(), even if num_bios is 1, to consistently
+	 * support allocating using GFP_NOWAIT with GFP_NOIO fallback.
+	 */
+	alloc_multiple_bios(&blist, ci, ti, num_bios, len, gfp_flag);
+	while ((clone = bio_list_pop(&blist))) {
+		if (num_bios > 1)
 			dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO);
-			__map_bio(clone);
-			ret += 1;
-		}
-		break;
+		__map_bio(clone);
+		ret += 1;
 	}
 
 	return ret;
@@ -1553,8 +1561,12 @@ static void __send_empty_flush(struct clone_info *ci)
 		unsigned int bios;
 		struct dm_target *ti = dm_table_get_target(t, i);
 
+		if (unlikely(ti->num_flush_bios == 0))
+			continue;
+
 		atomic_add(ti->num_flush_bios, &ci->io->io_count);
-		bios = __send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);
+		bios = __send_duplicate_bios(ci, ti, ti->num_flush_bios,
+					     NULL, GFP_NOWAIT);
 		atomic_sub(ti->num_flush_bios - bios, &ci->io->io_count);
 	}
 
@@ -1567,10 +1579,9 @@ static void __send_empty_flush(struct clone_info *ci)
 	bio_uninit(ci->bio);
 }
 
-static void __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
-					unsigned int num_bios,
-					unsigned int max_granularity,
-					unsigned int max_sectors)
+static void __send_abnormal_io(struct clone_info *ci, struct dm_target *ti,
+			       unsigned int num_bios, unsigned int max_granularity,
+			       unsigned int max_sectors)
 {
 	unsigned int len, bios;
 
@@ -1578,7 +1589,7 @@ static void __send_changing_extent_only(struct clone_info *ci, struct dm_target
 		    __max_io_len(ti, ci->sector, max_granularity, max_sectors));
 
 	atomic_add(num_bios, &ci->io->io_count);
-	bios = __send_duplicate_bios(ci, ti, num_bios, &len);
+	bios = __send_duplicate_bios(ci, ti, num_bios, &len, GFP_NOIO);
 	/*
 	 * alloc_io() takes one extra reference for submission, so the
 	 * reference won't reach 0 without the following (+1) subtraction
@@ -1647,8 +1658,8 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
 	if (unlikely(!num_bios))
 		return BLK_STS_NOTSUPP;
 
-	__send_changing_extent_only(ci, ti, num_bios,
-				    max_granularity, max_sectors);
+	__send_abnormal_io(ci, ti, num_bios, max_granularity, max_sectors);
+
 	return BLK_STS_OK;
 }
 
@@ -1707,10 +1718,6 @@ 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);
 
@@ -1722,7 +1729,17 @@ 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;
@@ -1731,11 +1748,11 @@ 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;
@@ -1770,8 +1787,18 @@ 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);