cleanup bio_kmalloc

cleanup bio_kmalloc

[Christoph Hellwig]

Hi Jens,

this series finishes off the bio allocation interface cleanups by dealing
with the weirdest member of the famility.  bio_kmalloc combines a kmalloc
for the bio and bio_vecs with a hidden bio_init call and magic cleanup
semantics.

This series moves a few callers away from bio_kmalloc and then turns
bio_kmalloc into a simple wrapper for a slab allocation of a bio and the
inline biovecs.  The callers need to manually call bio_init instead with
all that entails and the magic that turns bio_put into a kfree goes away
as well, allowing for a proper debug check in bio_put that catches
accidental use on a bio_init()ed bio.

Diffstat:
 block/bio.c                        |   47 ++++++++++++++-----------------------
 block/blk-crypto-fallback.c        |   14 ++++++-----
 block/blk-map.c                    |   42 +++++++++++++++++++++------------
 drivers/block/pktcdvd.c            |   34 +++++++++++---------------
 drivers/md/bcache/debug.c          |   10 ++++---
 drivers/md/dm-bufio.c              |    9 +++----
 drivers/md/raid1.c                 |   12 ++++++---
 drivers/md/raid10.c                |   21 +++++++++++-----
 drivers/target/target_core_pscsi.c |   36 ++++------------------------
 fs/btrfs/disk-io.c                 |    8 +++---
 fs/btrfs/volumes.c                 |   11 --------
 fs/btrfs/volumes.h                 |    2 -
 fs/squashfs/block.c                |   14 +++--------
 include/linux/bio.h                |    2 -
 14 files changed, 116 insertions(+), 146 deletions(-)

[PATCH 1/5] btrfs: simplify ->flush_bio handling

[Christoph Hellwig]

Use and embedded bios that is initialized when used instead of
bio_kmalloc plus bio_reset.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/btrfs/disk-io.c |  8 +++++---
 fs/btrfs/volumes.c | 11 -----------
 fs/btrfs/volumes.h |  2 +-
 3 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 505ba21230b1f..7d4229c769ac6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4127,6 +4127,7 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)
  */
 static void btrfs_end_empty_barrier(struct bio *bio)
 {
+	bio_uninit(bio);
 	complete(bio->bi_private);
 }
 
@@ -4136,7 +4137,7 @@ static void btrfs_end_empty_barrier(struct bio *bio)
  */
 static void write_dev_flush(struct btrfs_device *device)
 {
-	struct bio *bio = device->flush_bio;
+	struct bio *bio = &device->flush_bio;
 
 #ifndef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 	/*
@@ -4154,7 +4155,8 @@ static void write_dev_flush(struct btrfs_device *device)
 		return;
 #endif
 
-	bio_reset(bio, device->bdev, REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
+	bio_init(bio, device->bdev, NULL, 0,
+		 REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
 	bio->bi_end_io = btrfs_end_empty_barrier;
 	init_completion(&device->flush_wait);
 	bio->bi_private = &device->flush_wait;
@@ -4168,7 +4170,7 @@ static void write_dev_flush(struct btrfs_device *device)
  */
 static blk_status_t wait_dev_flush(struct btrfs_device *device)
 {
-	struct bio *bio = device->flush_bio;
+	struct bio *bio = &device->flush_bio;
 
 	if (!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state))
 		return BLK_STS_OK;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b07d382d53a86..7015b3096f724 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -405,7 +405,6 @@ void btrfs_free_device(struct btrfs_device *device)
 	WARN_ON(!list_empty(&device->post_commit_list));
 	rcu_string_free(device->name);
 	extent_io_tree_release(&device->alloc_state);
-	bio_put(device->flush_bio);
 	btrfs_destroy_dev_zone_info(device);
 	kfree(device);
 }
@@ -6962,16 +6961,6 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
-	/*
-	 * Preallocate a bio that's always going to be used for flushing device
-	 * barriers and matches the device lifespan
-	 */
-	dev->flush_bio = bio_kmalloc(GFP_KERNEL, 0);
-	if (!dev->flush_bio) {
-		kfree(dev);
-		return ERR_PTR(-ENOMEM);
-	}
-
 	INIT_LIST_HEAD(&dev->dev_list);
 	INIT_LIST_HEAD(&dev->dev_alloc_list);
 	INIT_LIST_HEAD(&dev->post_commit_list);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 005c9e2a491a1..9af7b6211920c 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -117,7 +117,7 @@ struct btrfs_device {
 	u64 commit_bytes_used;
 
 	/* for sending down flush barriers */
-	struct bio *flush_bio;
+	struct bio flush_bio;
 	struct completion flush_wait;
 
 	/* per-device scrub information */
-- 
2.30.2

Re: [PATCH 1/5] btrfs: simplify ->flush_bio handling

[David Sterba]

On Tue, Mar 01, 2022 at 10:45:48AM +0200, Christoph Hellwig wrote:
> @@ -6962,16 +6961,6 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
>  	if (!dev)
>  		return ERR_PTR(-ENOMEM);
>  
> -	/*
> -	 * Preallocate a bio that's always going to be used for flushing device
> -	 * barriers and matches the device lifespan
> -	 */
> -	dev->flush_bio = bio_kmalloc(GFP_KERNEL, 0);
> -	if (!dev->flush_bio) {
> -		kfree(dev);
> -		return ERR_PTR(-ENOMEM);
> -	}
> -
>  	INIT_LIST_HEAD(&dev->dev_list);
>  	INIT_LIST_HEAD(&dev->dev_alloc_list);
>  	INIT_LIST_HEAD(&dev->post_commit_list);
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 005c9e2a491a1..9af7b6211920c 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -117,7 +117,7 @@ struct btrfs_device {
>  	u64 commit_bytes_used;
>  
>  	/* for sending down flush barriers */
> -	struct bio *flush_bio;

Please add this comment to the struct member declaration:

	/* Bio used for flushing device barriers */

> +	struct bio flush_bio;

Otherwise

Reviewed-by: David Sterba <dsterba@suse.com>

Thanks.

[PATCH 2/5] squashfs: always use bio_kmalloc in squashfs_bio_read

[Christoph Hellwig]

If a plain kmalloc that is not backed by a mempool is safe here for a
large read (and the actual page allocations), it must also be for a
small one, so simplify the code a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/squashfs/block.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 622c844f6d118..4311a32218928 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -86,16 +86,11 @@ static int squashfs_bio_read(struct super_block *sb, u64 index, int length,
 	int error, i;
 	struct bio *bio;
 
-	if (page_count <= BIO_MAX_VECS) {
-		bio = bio_alloc(sb->s_bdev, page_count, REQ_OP_READ, GFP_NOIO);
-	} else {
-		bio = bio_kmalloc(GFP_NOIO, page_count);
-		bio_set_dev(bio, sb->s_bdev);
-		bio->bi_opf = REQ_OP_READ;
-	}
-
+	bio = bio_kmalloc(GFP_NOIO, page_count);
 	if (!bio)
 		return -ENOMEM;
+	bio_set_dev(bio, sb->s_bdev);
+	bio->bi_opf = REQ_OP_READ;
 
 	bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT);
 
-- 
2.30.2

Re: [PATCH 2/5] squashfs: always use bio_kmalloc in squashfs_bio_read

[Phillip Lougher]

On 01/03/2022 08:45, Christoph Hellwig wrote:
> If a plain kmalloc that is not backed by a mempool is safe here for a
> large read (and the actual page allocations), it must also be for a
> small one, so simplify the code a bit.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Acked-by: Phillip Lougher <phillip@squashfs.org.uk>

[PATCH 3/5] target/pscsi: remove pscsi_get_bio

[Christoph Hellwig]

Remove pscsi_get_bio and simplify the code flow in the only caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/target/target_core_pscsi.c | 28 ++--------------------------
 1 file changed, 2 insertions(+), 26 deletions(-)

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 0fae71ac5cc8a..bd8ae07273f14 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -823,23 +823,6 @@ static void pscsi_bi_endio(struct bio *bio)
 	bio_put(bio);
 }
 
-static inline struct bio *pscsi_get_bio(int nr_vecs)
-{
-	struct bio *bio;
-	/*
-	 * Use bio_malloc() following the comment in for bio -> struct request
-	 * in block/blk-core.c:blk_make_request()
-	 */
-	bio = bio_kmalloc(GFP_KERNEL, nr_vecs);
-	if (!bio) {
-		pr_err("PSCSI: bio_kmalloc() failed\n");
-		return NULL;
-	}
-	bio->bi_end_io = pscsi_bi_endio;
-
-	return bio;
-}
-
 static sense_reason_t
 pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 		struct request *req)
@@ -880,12 +863,10 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 			if (!bio) {
 new_bio:
 				nr_vecs = bio_max_segs(nr_pages);
-				/*
-				 * Calls bio_kmalloc() and sets bio->bi_end_io()
-				 */
-				bio = pscsi_get_bio(nr_vecs);
+				bio = bio_kmalloc(GFP_KERNEL, nr_vecs);
 				if (!bio)
 					goto fail;
+				bio->bi_end_io = pscsi_bi_endio;
 
 				if (rw)
 					bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
@@ -914,11 +895,6 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 					goto fail;
 				}
 
-				/*
-				 * Clear the pointer so that another bio will
-				 * be allocated with pscsi_get_bio() above.
-				 */
-				bio = NULL;
 				goto new_bio;
 			}
 
-- 
2.30.2

Re: [PATCH 3/5] target/pscsi: remove pscsi_get_bio

[Martin K. Petersen]

Christoph,

> Remove pscsi_get_bio and simplify the code flow in the only caller.

Looks good to me.

Acked-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering

[PATCH 4/5] block: turn bio_kmalloc into a simple kmalloc wrapper

[Christoph Hellwig]

Remove the magic autofree semantics and require the callers to explicitly
call bio_init to initialize the bio.

This allows bio_free to catch accidental bio_put calls on bio_init()ed
bios as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/bio.c                        | 47 ++++++++++++------------------
 block/blk-crypto-fallback.c        | 14 +++++----
 block/blk-map.c                    | 42 ++++++++++++++++----------
 drivers/block/pktcdvd.c            | 25 ++++++++--------
 drivers/md/bcache/debug.c          | 10 ++++---
 drivers/md/dm-bufio.c              |  9 +++---
 drivers/md/raid1.c                 | 12 +++++---
 drivers/md/raid10.c                | 21 ++++++++-----
 drivers/target/target_core_pscsi.c | 10 +++----
 fs/squashfs/block.c                |  9 +++---
 include/linux/bio.h                |  2 +-
 11 files changed, 108 insertions(+), 93 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index b15f5466ce084..e8ff5dd6d145f 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -224,24 +224,13 @@ EXPORT_SYMBOL(bio_uninit);
 static void bio_free(struct bio *bio)
 {
 	struct bio_set *bs = bio->bi_pool;
-	void *p;
-
-	bio_uninit(bio);
+	void *p = bio;
 
-	if (bs) {
-		bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs);
+	WARN_ON_ONCE(!bs);
 
-		/*
-		 * If we have front padding, adjust the bio pointer before freeing
-		 */
-		p = bio;
-		p -= bs->front_pad;
-
-		mempool_free(p, &bs->bio_pool);
-	} else {
-		/* Bio was allocated by bio_kmalloc() */
-		kfree(bio);
-	}
+	bio_uninit(bio);
+	bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs);
+	mempool_free(p - bs->front_pad, &bs->bio_pool);
 }
 
 /*
@@ -529,28 +518,28 @@ struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs,
 EXPORT_SYMBOL(bio_alloc_bioset);
 
 /**
- * bio_kmalloc - kmalloc a bio for I/O
+ * bio_kmalloc - kmalloc a bio
+ * @nr_vecs:	number of bio_vecs to allocate
  * @gfp_mask:   the GFP_* mask given to the slab allocator
- * @nr_iovecs:	number of iovecs to pre-allocate
  *
- * Use kmalloc to allocate and initialize a bio.
+ * Use kmalloc to allocate a bio (including bvecs).  The bio must be initialized
+ * using bio_init() before use.  To free a bio returned from this function use
+ * kfree() after calling bio_uninit().  A bio returned from this function can
+ * be reused by calling bio_uninit() before calling bio_init() again.
+ *
+ * Note that unlike bio_alloc() or bio_alloc_bioset() allocations from this
+ * function are not backed by a mempool can can fail.  Do not use this function
+ * for allocations in the file system I/O path.
  *
  * Returns: Pointer to new bio on success, NULL on failure.
  */
-struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned short nr_iovecs)
+struct bio *bio_kmalloc(unsigned short nr_vecs, gfp_t gfp_mask)
 {
 	struct bio *bio;
 
-	if (nr_iovecs > UIO_MAXIOV)
+	if (nr_vecs > UIO_MAXIOV)
 		return NULL;
-
-	bio = kmalloc(struct_size(bio, bi_inline_vecs, nr_iovecs), gfp_mask);
-	if (unlikely(!bio))
-		return NULL;
-	bio_init(bio, NULL, nr_iovecs ? bio->bi_inline_vecs : NULL, nr_iovecs,
-		 0);
-	bio->bi_pool = NULL;
-	return bio;
+	return kmalloc(struct_size(bio, bi_inline_vecs, nr_vecs), gfp_mask);
 }
 EXPORT_SYMBOL(bio_kmalloc);
 
diff --git a/block/blk-crypto-fallback.c b/block/blk-crypto-fallback.c
index 18c8eafe20b94..1a624b75da94f 100644
--- a/block/blk-crypto-fallback.c
+++ b/block/blk-crypto-fallback.c
@@ -152,23 +152,25 @@ static void blk_crypto_fallback_encrypt_endio(struct bio *enc_bio)
 
 	src_bio->bi_status = enc_bio->bi_status;
 
-	bio_put(enc_bio);
+	bio_uninit(enc_bio);
+	kfree(enc_bio);
 	bio_endio(src_bio);
 }
 
 static struct bio *blk_crypto_fallback_clone_bio(struct bio *bio_src)
 {
+	unsigned int nr_segs = bio_segments(bio_src);
 	struct bvec_iter iter;
 	struct bio_vec bv;
 	struct bio *bio;
 
-	bio = bio_kmalloc(GFP_NOIO, bio_segments(bio_src));
+	bio = bio_kmalloc(nr_segs, GFP_NOIO);
 	if (!bio)
 		return NULL;
-	bio->bi_bdev		= bio_src->bi_bdev;
+	bio_init(bio, bio_src->bi_bdev, bio->bi_inline_vecs, nr_segs,
+		 bio_src->bi_opf);
 	if (bio_flagged(bio_src, BIO_REMAPPED))
 		bio_set_flag(bio, BIO_REMAPPED);
-	bio->bi_opf		= bio_src->bi_opf;
 	bio->bi_ioprio		= bio_src->bi_ioprio;
 	bio->bi_write_hint	= bio_src->bi_write_hint;
 	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
@@ -364,8 +366,8 @@ static bool blk_crypto_fallback_encrypt_bio(struct bio **bio_ptr)
 	blk_crypto_put_keyslot(slot);
 out_put_enc_bio:
 	if (enc_bio)
-		bio_put(enc_bio);
-
+		bio_uninit(enc_bio);
+	kfree(enc_bio);
 	return ret;
 }
 
diff --git a/block/blk-map.c b/block/blk-map.c
index 4526adde01564..59be60e69e7af 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -152,10 +152,10 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
 	nr_pages = bio_max_segs(DIV_ROUND_UP(offset + len, PAGE_SIZE));
 
 	ret = -ENOMEM;
-	bio = bio_kmalloc(gfp_mask, nr_pages);
+	bio = bio_kmalloc(nr_pages, gfp_mask);
 	if (!bio)
 		goto out_bmd;
-	bio->bi_opf |= req_op(rq);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, req_op(rq));
 
 	if (map_data) {
 		nr_pages = 1 << map_data->page_order;
@@ -224,7 +224,8 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
 cleanup:
 	if (!map_data)
 		bio_free_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 out_bmd:
 	kfree(bmd);
 	return ret;
@@ -234,6 +235,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 		gfp_t gfp_mask)
 {
 	unsigned int max_sectors = queue_max_hw_sectors(rq->q);
+	unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
 	struct bio *bio;
 	int ret;
 	int j;
@@ -241,10 +243,10 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 	if (!iov_iter_count(iter))
 		return -EINVAL;
 
-	bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_VECS));
+	bio = bio_kmalloc(nr_vecs, gfp_mask);
 	if (!bio)
 		return -ENOMEM;
-	bio->bi_opf |= req_op(rq);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
 
 	while (iov_iter_count(iter)) {
 		struct page **pages;
@@ -303,7 +305,8 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 
  out_unmap:
 	bio_release_pages(bio, false);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 	return ret;
 }
 
@@ -323,7 +326,8 @@ static void bio_invalidate_vmalloc_pages(struct bio *bio)
 static void bio_map_kern_endio(struct bio *bio)
 {
 	bio_invalidate_vmalloc_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 }
 
 /**
@@ -348,9 +352,10 @@ static struct bio *bio_map_kern(struct request_queue *q, void *data,
 	int offset, i;
 	struct bio *bio;
 
-	bio = bio_kmalloc(gfp_mask, nr_pages);
+	bio = bio_kmalloc(nr_pages, gfp_mask);
 	if (!bio)
 		return ERR_PTR(-ENOMEM);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
 
 	if (is_vmalloc) {
 		flush_kernel_vmap_range(data, len);
@@ -374,7 +379,8 @@ static struct bio *bio_map_kern(struct request_queue *q, void *data,
 		if (bio_add_pc_page(q, bio, page, bytes,
 				    offset) < bytes) {
 			/* we don't support partial mappings */
-			bio_put(bio);
+			bio_uninit(bio);
+			kfree(bio);
 			return ERR_PTR(-EINVAL);
 		}
 
@@ -390,7 +396,8 @@ static struct bio *bio_map_kern(struct request_queue *q, void *data,
 static void bio_copy_kern_endio(struct bio *bio)
 {
 	bio_free_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 }
 
 static void bio_copy_kern_endio_read(struct bio *bio)
@@ -435,9 +442,10 @@ static struct bio *bio_copy_kern(struct request_queue *q, void *data,
 		return ERR_PTR(-EINVAL);
 
 	nr_pages = end - start;
-	bio = bio_kmalloc(gfp_mask, nr_pages);
+	bio = bio_kmalloc(nr_pages, gfp_mask);
 	if (!bio)
 		return ERR_PTR(-ENOMEM);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
 
 	while (len) {
 		struct page *page;
@@ -471,7 +479,8 @@ static struct bio *bio_copy_kern(struct request_queue *q, void *data,
 
 cleanup:
 	bio_free_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 	return ERR_PTR(-ENOMEM);
 }
 
@@ -602,7 +611,8 @@ int blk_rq_unmap_user(struct bio *bio)
 
 		next_bio = bio;
 		bio = bio->bi_next;
-		bio_put(next_bio);
+		bio_uninit(next_bio);
+		kfree(next_bio);
 	}
 
 	return ret;
@@ -648,8 +658,10 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	bio->bi_opf |= req_op(rq);
 
 	ret = blk_rq_append_bio(rq, bio);
-	if (unlikely(ret))
-		bio_put(bio);
+	if (unlikely(ret)) {
+		bio_uninit(bio);
+		kfree(bio);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(blk_rq_map_kern);
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index be749c686feb7..6aec11ed185d8 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -522,9 +522,10 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
 		goto no_pkt;
 
 	pkt->frames = frames;
-	pkt->w_bio = bio_kmalloc(GFP_KERNEL, frames);
+	pkt->w_bio = bio_kmalloc(frames, GFP_KERNEL);
 	if (!pkt->w_bio)
 		goto no_bio;
+	bio_init(pkt->w_bio, NULL, pkt->w_bio->bi_inline_vecs, frames, 0);
 
 	for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
 		pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
@@ -536,10 +537,10 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
 	bio_list_init(&pkt->orig_bios);
 
 	for (i = 0; i < frames; i++) {
-		struct bio *bio = bio_kmalloc(GFP_KERNEL, 1);
+		struct bio *bio = bio_kmalloc(1, GFP_KERNEL);
 		if (!bio)
 			goto no_rd_bio;
-
+		bio_init(bio, NULL, bio->bi_inline_vecs, 1, 0);
 		pkt->r_bios[i] = bio;
 	}
 
@@ -547,16 +548,16 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
 
 no_rd_bio:
 	for (i = 0; i < frames; i++) {
-		struct bio *bio = pkt->r_bios[i];
-		if (bio)
-			bio_put(bio);
+		if (pkt->r_bios[i])
+			bio_uninit(pkt->r_bios[i]);
+		kfree(pkt->r_bios[i]);
 	}
-
 no_page:
 	for (i = 0; i < frames / FRAMES_PER_PAGE; i++)
 		if (pkt->pages[i])
 			__free_page(pkt->pages[i]);
-	bio_put(pkt->w_bio);
+	bio_uninit(pkt->w_bio);
+	kfree(pkt->w_bio);
 no_bio:
 	kfree(pkt);
 no_pkt:
@@ -571,13 +572,13 @@ static void pkt_free_packet_data(struct packet_data *pkt)
 	int i;
 
 	for (i = 0; i < pkt->frames; i++) {
-		struct bio *bio = pkt->r_bios[i];
-		if (bio)
-			bio_put(bio);
+		bio_uninit(pkt->r_bios[i]);
+		kfree(pkt->r_bios[i]);
 	}
 	for (i = 0; i < pkt->frames / FRAMES_PER_PAGE; i++)
 		__free_page(pkt->pages[i]);
-	bio_put(pkt->w_bio);
+	bio_uninit(pkt->w_bio);
+	kfree(pkt->w_bio);
 	kfree(pkt);
 }
 
diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index 6230dfdd9286e..7510d1c983a5e 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c
@@ -107,15 +107,16 @@ void bch_btree_verify(struct btree *b)
 
 void bch_data_verify(struct cached_dev *dc, struct bio *bio)
 {
+	unsigned int nr_segs = bio_segments(bio);
 	struct bio *check;
 	struct bio_vec bv, cbv;
 	struct bvec_iter iter, citer = { 0 };
 
-	check = bio_kmalloc(GFP_NOIO, bio_segments(bio));
+	check = bio_kmalloc(nr_segs, GFP_NOIO);
 	if (!check)
 		return;
-	bio_set_dev(check, bio->bi_bdev);
-	check->bi_opf = REQ_OP_READ;
+	bio_init(check, bio->bi_bdev, check->bi_inline_vecs, nr_segs,
+		 REQ_OP_READ);
 	check->bi_iter.bi_sector = bio->bi_iter.bi_sector;
 	check->bi_iter.bi_size = bio->bi_iter.bi_size;
 
@@ -146,7 +147,8 @@ void bch_data_verify(struct cached_dev *dc, struct bio *bio)
 
 	bio_free_pages(check);
 out_put:
-	bio_put(check);
+	bio_uninit(check);
+	kfree(check);
 }
 
 #endif
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index e9cbc70d5a0ee..5ffa1dcf84cfc 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -611,7 +611,8 @@ static void bio_complete(struct bio *bio)
 {
 	struct dm_buffer *b = bio->bi_private;
 	blk_status_t status = bio->bi_status;
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 	b->end_io(b, status);
 }
 
@@ -626,16 +627,14 @@ static void use_bio(struct dm_buffer *b, int rw, sector_t sector,
 	if (unlikely(b->c->sectors_per_block_bits < PAGE_SHIFT - SECTOR_SHIFT))
 		vec_size += 2;
 
-	bio = bio_kmalloc(GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN, vec_size);
+	bio = bio_kmalloc(vec_size, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN);
 	if (!bio) {
 dmio:
 		use_dmio(b, rw, sector, n_sectors, offset);
 		return;
 	}
-
+	bio_init(bio, b->c->bdev, bio->bi_inline_vecs, vec_size, rw);
 	bio->bi_iter.bi_sector = sector;
-	bio_set_dev(bio, b->c->bdev);
-	bio_set_op_attrs(bio, rw, 0);
 	bio->bi_end_io = bio_complete;
 	bio->bi_private = b;
 
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c3288d46948de..12627d1c99c36 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -165,9 +165,10 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 	 * Allocate bios : 1 for reading, n-1 for writing
 	 */
 	for (j = pi->raid_disks ; j-- ; ) {
-		bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
+		bio = bio_kmalloc(RESYNC_PAGES, gfp_flags);
 		if (!bio)
 			goto out_free_bio;
+		bio_init(bio, NULL, bio->bi_inline_vecs, RESYNC_PAGES, 0);
 		r1_bio->bios[j] = bio;
 	}
 	/*
@@ -206,8 +207,10 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 		resync_free_pages(&rps[j]);
 
 out_free_bio:
-	while (++j < pi->raid_disks)
-		bio_put(r1_bio->bios[j]);
+	while (++j < pi->raid_disks) {
+		bio_uninit(r1_bio->bios[j]);
+		kfree(r1_bio->bios[j]);
+	}
 	kfree(rps);
 
 out_free_r1bio:
@@ -225,7 +228,8 @@ static void r1buf_pool_free(void *__r1_bio, void *data)
 	for (i = pi->raid_disks; i--; ) {
 		rp = get_resync_pages(r1bio->bios[i]);
 		resync_free_pages(rp);
-		bio_put(r1bio->bios[i]);
+		bio_uninit(r1bio->bios[i]);
+		kfree(r1bio->bios[i]);
 	}
 
 	/* resync pages array stored in the 1st bio's .bi_private */
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 5dd2e17e1d0ea..781b7b8a4b558 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -145,15 +145,17 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 	 * Allocate bios.
 	 */
 	for (j = nalloc ; j-- ; ) {
-		bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
+		bio = bio_kmalloc(RESYNC_PAGES, gfp_flags);
 		if (!bio)
 			goto out_free_bio;
+		bio_init(bio, NULL, bio->bi_inline_vecs, RESYNC_PAGES, 0);
 		r10_bio->devs[j].bio = bio;
 		if (!conf->have_replacement)
 			continue;
-		bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
+		bio = bio_kmalloc(RESYNC_PAGES, gfp_flags);
 		if (!bio)
 			goto out_free_bio;
+		bio_init(bio, NULL, bio->bi_inline_vecs, RESYNC_PAGES, 0);
 		r10_bio->devs[j].repl_bio = bio;
 	}
 	/*
@@ -197,9 +199,11 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 out_free_bio:
 	for ( ; j < nalloc; j++) {
 		if (r10_bio->devs[j].bio)
-			bio_put(r10_bio->devs[j].bio);
+			bio_uninit(r10_bio->devs[j].bio);
+		kfree(r10_bio->devs[j].bio);
 		if (r10_bio->devs[j].repl_bio)
-			bio_put(r10_bio->devs[j].repl_bio);
+			bio_uninit(r10_bio->devs[j].repl_bio);
+		kfree(r10_bio->devs[j].repl_bio);
 	}
 	kfree(rps);
 out_free_r10bio:
@@ -220,12 +224,15 @@ static void r10buf_pool_free(void *__r10_bio, void *data)
 		if (bio) {
 			rp = get_resync_pages(bio);
 			resync_free_pages(rp);
-			bio_put(bio);
+			bio_uninit(bio);
+			kfree(bio);
 		}
 
 		bio = r10bio->devs[j].repl_bio;
-		if (bio)
-			bio_put(bio);
+		if (bio) {
+			bio_uninit(bio);
+			kfree(bio);
+		}
 	}
 
 	/* resync pages array stored in the 1st bio's .bi_private */
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index bd8ae07273f14..edda1a89d9357 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -820,7 +820,8 @@ static ssize_t pscsi_show_configfs_dev_params(struct se_device *dev, char *b)
 
 static void pscsi_bi_endio(struct bio *bio)
 {
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 }
 
 static sense_reason_t
@@ -863,14 +864,13 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 			if (!bio) {
 new_bio:
 				nr_vecs = bio_max_segs(nr_pages);
-				bio = bio_kmalloc(GFP_KERNEL, nr_vecs);
+				bio = bio_kmalloc(nr_vecs, GFP_KERNEL);
 				if (!bio)
 					goto fail;
+				bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs,
+					 rw ? REQ_OP_WRITE : REQ_OP_READ);
 				bio->bi_end_io = pscsi_bi_endio;
 
-				if (rw)
-					bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
-
 				pr_debug("PSCSI: Allocated bio: %p,"
 					" dir: %s nr_vecs: %d\n", bio,
 					(rw) ? "rw" : "r", nr_vecs);
diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 4311a32218928..930eb530fa622 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -86,12 +86,10 @@ static int squashfs_bio_read(struct super_block *sb, u64 index, int length,
 	int error, i;
 	struct bio *bio;
 
-	bio = bio_kmalloc(GFP_NOIO, page_count);
+	bio = bio_kmalloc(page_count, GFP_NOIO);
 	if (!bio)
 		return -ENOMEM;
-	bio_set_dev(bio, sb->s_bdev);
-	bio->bi_opf = REQ_OP_READ;
-
+	bio_init(bio, sb->s_bdev, bio->bi_inline_vecs, page_count, REQ_OP_READ);
 	bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT);
 
 	for (i = 0; i < page_count; ++i) {
@@ -121,7 +119,8 @@ static int squashfs_bio_read(struct super_block *sb, u64 index, int length,
 
 out_free_bio:
 	bio_free_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 	return error;
 }
 
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 7523aba4ddf7c..9c01b6f516120 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -410,7 +410,7 @@ struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs,
 			     struct bio_set *bs);
 struct bio *bio_alloc_kiocb(struct kiocb *kiocb, struct block_device *bdev,
 		unsigned short nr_vecs, unsigned int opf, struct bio_set *bs);
-struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned short nr_iovecs);
+struct bio *bio_kmalloc(unsigned short nr_vecs, gfp_t gfp_mask);
 extern void bio_put(struct bio *);
 
 struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
-- 
2.30.2

[PATCH 5/5] pktcdvd: stop using bio_reset

[Christoph Hellwig]

Just initialize the bios on-demand.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/pktcdvd.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 6aec11ed185d8..e4ee7856483cf 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -525,7 +525,6 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
 	pkt->w_bio = bio_kmalloc(frames, GFP_KERNEL);
 	if (!pkt->w_bio)
 		goto no_bio;
-	bio_init(pkt->w_bio, NULL, pkt->w_bio->bi_inline_vecs, frames, 0);
 
 	for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
 		pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
@@ -537,26 +536,20 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
 	bio_list_init(&pkt->orig_bios);
 
 	for (i = 0; i < frames; i++) {
-		struct bio *bio = bio_kmalloc(1, GFP_KERNEL);
-		if (!bio)
+		pkt->r_bios[i] = bio_kmalloc(1, GFP_KERNEL);
+		if (!pkt->r_bios[i])
 			goto no_rd_bio;
-		bio_init(bio, NULL, bio->bi_inline_vecs, 1, 0);
-		pkt->r_bios[i] = bio;
 	}
 
 	return pkt;
 
 no_rd_bio:
-	for (i = 0; i < frames; i++) {
-		if (pkt->r_bios[i])
-			bio_uninit(pkt->r_bios[i]);
+	for (i = 0; i < frames; i++)
 		kfree(pkt->r_bios[i]);
-	}
 no_page:
 	for (i = 0; i < frames / FRAMES_PER_PAGE; i++)
 		if (pkt->pages[i])
 			__free_page(pkt->pages[i]);
-	bio_uninit(pkt->w_bio);
 	kfree(pkt->w_bio);
 no_bio:
 	kfree(pkt);
@@ -571,13 +564,10 @@ static void pkt_free_packet_data(struct packet_data *pkt)
 {
 	int i;
 
-	for (i = 0; i < pkt->frames; i++) {
-		bio_uninit(pkt->r_bios[i]);
+	for (i = 0; i < pkt->frames; i++)
 		kfree(pkt->r_bios[i]);
-	}
 	for (i = 0; i < pkt->frames / FRAMES_PER_PAGE; i++)
 		__free_page(pkt->pages[i]);
-	bio_uninit(pkt->w_bio);
 	kfree(pkt->w_bio);
 	kfree(pkt);
 }
@@ -950,6 +940,7 @@ static void pkt_end_io_read(struct bio *bio)
 
 	if (bio->bi_status)
 		atomic_inc(&pkt->io_errors);
+	bio_uninit(bio);
 	if (atomic_dec_and_test(&pkt->io_wait)) {
 		atomic_inc(&pkt->run_sm);
 		wake_up(&pd->wqueue);
@@ -967,6 +958,7 @@ static void pkt_end_io_packet_write(struct bio *bio)
 
 	pd->stats.pkt_ended++;
 
+	bio_uninit(bio);
 	pkt_bio_finished(pd);
 	atomic_dec(&pkt->io_wait);
 	atomic_inc(&pkt->run_sm);
@@ -1021,7 +1013,7 @@ static void pkt_gather_data(struct pktcdvd_device *pd, struct packet_data *pkt)
 			continue;
 
 		bio = pkt->r_bios[f];
-		bio_reset(bio, pd->bdev, REQ_OP_READ);
+		bio_init(bio, pd->bdev, bio->bi_inline_vecs, 1, REQ_OP_READ);
 		bio->bi_iter.bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
 		bio->bi_end_io = pkt_end_io_read;
 		bio->bi_private = pkt;
@@ -1234,7 +1226,8 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
 {
 	int f;
 
-	bio_reset(pkt->w_bio, pd->bdev, REQ_OP_WRITE);
+	bio_init(pkt->w_bio, pd->bdev, pkt->w_bio->bi_inline_vecs, pkt->frames,
+		 REQ_OP_WRITE);
 	pkt->w_bio->bi_iter.bi_sector = pkt->sector;
 	pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
 	pkt->w_bio->bi_private = pkt;
-- 
2.30.2

cleanup bio_kmalloc v2

[Christoph Hellwig]

Hi Jens,

this series finishes off the bio allocation interface cleanups by dealing
with the weirdest member of the famility.  bio_kmalloc combines a kmalloc
for the bio and bio_vecs with a hidden bio_init call and magic cleanup
semantics.

This series moves a few callers away from bio_kmalloc and then turns
bio_kmalloc into a simple wrapper for a slab allocation of a bio and the
inline biovecs.  The callers need to manually call bio_init instead with
all that entails and the magic that turns bio_put into a kfree goes away
as well, allowing for a proper debug check in bio_put that catches
accidental use on a bio_init()ed bio.

Changes since v1:
 - update a pre-existing comment per maintainer suggestion

Diffstat:
 block/bio.c                        |   47 ++++++++++++++-----------------------
 block/blk-crypto-fallback.c        |   14 ++++++-----
 block/blk-map.c                    |   42 +++++++++++++++++++++------------
 drivers/block/pktcdvd.c            |   34 +++++++++++---------------
 drivers/md/bcache/debug.c          |   10 ++++---
 drivers/md/dm-bufio.c              |    9 +++----
 drivers/md/raid1.c                 |   12 ++++++---
 drivers/md/raid10.c                |   21 +++++++++++-----
 drivers/target/target_core_pscsi.c |   36 ++++------------------------
 fs/btrfs/disk-io.c                 |    8 +++---
 fs/btrfs/volumes.c                 |   11 --------
 fs/btrfs/volumes.h                 |    2 -
 fs/squashfs/block.c                |   14 +++--------
 include/linux/bio.h                |    2 -
 14 files changed, 116 insertions(+), 146 deletions(-)

[PATCH 1/5] btrfs: simplify ->flush_bio handling

[Christoph Hellwig]

Use and embedded bios that is initialized when used instead of
bio_kmalloc plus bio_reset.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/disk-io.c |  8 +++++---
 fs/btrfs/volumes.c | 11 -----------
 fs/btrfs/volumes.h |  4 ++--
 3 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 505ba21230b1f..7d4229c769ac6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4127,6 +4127,7 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)
  */
 static void btrfs_end_empty_barrier(struct bio *bio)
 {
+	bio_uninit(bio);
 	complete(bio->bi_private);
 }
 
@@ -4136,7 +4137,7 @@ static void btrfs_end_empty_barrier(struct bio *bio)
  */
 static void write_dev_flush(struct btrfs_device *device)
 {
-	struct bio *bio = device->flush_bio;
+	struct bio *bio = &device->flush_bio;
 
 #ifndef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 	/*
@@ -4154,7 +4155,8 @@ static void write_dev_flush(struct btrfs_device *device)
 		return;
 #endif
 
-	bio_reset(bio, device->bdev, REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
+	bio_init(bio, device->bdev, NULL, 0,
+		 REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
 	bio->bi_end_io = btrfs_end_empty_barrier;
 	init_completion(&device->flush_wait);
 	bio->bi_private = &device->flush_wait;
@@ -4168,7 +4170,7 @@ static void write_dev_flush(struct btrfs_device *device)
  */
 static blk_status_t wait_dev_flush(struct btrfs_device *device)
 {
-	struct bio *bio = device->flush_bio;
+	struct bio *bio = &device->flush_bio;
 
 	if (!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state))
 		return BLK_STS_OK;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b07d382d53a86..7015b3096f724 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -405,7 +405,6 @@ void btrfs_free_device(struct btrfs_device *device)
 	WARN_ON(!list_empty(&device->post_commit_list));
 	rcu_string_free(device->name);
 	extent_io_tree_release(&device->alloc_state);
-	bio_put(device->flush_bio);
 	btrfs_destroy_dev_zone_info(device);
 	kfree(device);
 }
@@ -6962,16 +6961,6 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
-	/*
-	 * Preallocate a bio that's always going to be used for flushing device
-	 * barriers and matches the device lifespan
-	 */
-	dev->flush_bio = bio_kmalloc(GFP_KERNEL, 0);
-	if (!dev->flush_bio) {
-		kfree(dev);
-		return ERR_PTR(-ENOMEM);
-	}
-
 	INIT_LIST_HEAD(&dev->dev_list);
 	INIT_LIST_HEAD(&dev->dev_alloc_list);
 	INIT_LIST_HEAD(&dev->post_commit_list);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 005c9e2a491a1..dbd6cc5e5cd3b 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -116,8 +116,8 @@ struct btrfs_device {
 	/* bytes used on the current transaction */
 	u64 commit_bytes_used;
 
-	/* for sending down flush barriers */
-	struct bio *flush_bio;
+	/* Bio used for flushing device barriers */
+	struct bio flush_bio;
 	struct completion flush_wait;
 
 	/* per-device scrub information */
-- 
2.30.2

Re: [PATCH 1/5] btrfs: simplify ->flush_bio handling

[Chaitanya Kulkarni]

On 3/7/22 22:15, Christoph Hellwig wrote:
> Use and embedded bios that is initialized when used instead of
> bio_kmalloc plus bio_reset.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: David Sterba <dsterba@suse.com>
> ---



Looks good.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

cleanup bio_kmalloc v3

[Christoph Hellwig]

Hi Jens,

this series finishes off the bio allocation interface cleanups by dealing
with the weirdest member of the famility.  bio_kmalloc combines a kmalloc
for the bio and bio_vecs with a hidden bio_init call and magic cleanup
semantics.

This series moves a few callers away from bio_kmalloc and then turns
bio_kmalloc into a simple wrapper for a slab allocation of a bio and the
inline biovecs.  The callers need to manually call bio_init instead with
all that entails and the magic that turns bio_put into a kfree goes away
as well, allowing for a proper debug check in bio_put that catches
accidental use on a bio_init()ed bio.

Changes since v2:
 - rebased to 5.18-rc1
 - fix bio freeing in squashfs

Changes since v1:
 - update a pre-existing comment per maintainer suggestion

Diffstat:
 block/bio.c                        |   47 ++++++++++++++-----------------------
 block/blk-crypto-fallback.c        |   14 ++++++-----
 block/blk-map.c                    |   42 +++++++++++++++++++++------------
 drivers/block/pktcdvd.c            |   34 +++++++++++---------------
 drivers/md/bcache/debug.c          |   10 ++++---
 drivers/md/dm-bufio.c              |    9 +++----
 drivers/md/raid1.c                 |   12 ++++++---
 drivers/md/raid10.c                |   21 +++++++++++-----
 drivers/target/target_core_pscsi.c |   36 ++++------------------------
 fs/btrfs/disk-io.c                 |    8 +++---
 fs/btrfs/volumes.c                 |   11 --------
 fs/btrfs/volumes.h                 |    2 -
 fs/squashfs/block.c                |   14 +++--------
 include/linux/bio.h                |    2 -
 14 files changed, 116 insertions(+), 146 deletions(-)

[PATCH 1/5] btrfs: simplify ->flush_bio handling

[Christoph Hellwig]

Use and embedded bios that is initialized when used instead of
bio_kmalloc plus bio_reset.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/disk-io.c |  8 +++++---
 fs/btrfs/volumes.c | 11 -----------
 fs/btrfs/volumes.h |  4 ++--
 3 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b30309f187cf0..51f4cdf6bcaea 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4225,6 +4225,7 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)
  */
 static void btrfs_end_empty_barrier(struct bio *bio)
 {
+	bio_uninit(bio);
 	complete(bio->bi_private);
 }
 
@@ -4234,7 +4235,7 @@ static void btrfs_end_empty_barrier(struct bio *bio)
  */
 static void write_dev_flush(struct btrfs_device *device)
 {
-	struct bio *bio = device->flush_bio;
+	struct bio *bio = &device->flush_bio;
 
 #ifndef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 	/*
@@ -4252,7 +4253,8 @@ static void write_dev_flush(struct btrfs_device *device)
 		return;
 #endif
 
-	bio_reset(bio, device->bdev, REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
+	bio_init(bio, device->bdev, NULL, 0,
+		 REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
 	bio->bi_end_io = btrfs_end_empty_barrier;
 	init_completion(&device->flush_wait);
 	bio->bi_private = &device->flush_wait;
@@ -4266,7 +4268,7 @@ static void write_dev_flush(struct btrfs_device *device)
  */
 static blk_status_t wait_dev_flush(struct btrfs_device *device)
 {
-	struct bio *bio = device->flush_bio;
+	struct bio *bio = &device->flush_bio;
 
 	if (!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state))
 		return BLK_STS_OK;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1be7cb2f955fc..00517239b5c01 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -405,7 +405,6 @@ void btrfs_free_device(struct btrfs_device *device)
 	WARN_ON(!list_empty(&device->post_commit_list));
 	rcu_string_free(device->name);
 	extent_io_tree_release(&device->alloc_state);
-	bio_put(device->flush_bio);
 	btrfs_destroy_dev_zone_info(device);
 	kfree(device);
 }
@@ -6956,16 +6955,6 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
-	/*
-	 * Preallocate a bio that's always going to be used for flushing device
-	 * barriers and matches the device lifespan
-	 */
-	dev->flush_bio = bio_kmalloc(GFP_KERNEL, 0);
-	if (!dev->flush_bio) {
-		kfree(dev);
-		return ERR_PTR(-ENOMEM);
-	}
-
 	INIT_LIST_HEAD(&dev->dev_list);
 	INIT_LIST_HEAD(&dev->dev_alloc_list);
 	INIT_LIST_HEAD(&dev->post_commit_list);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index bd297f23d19e7..628c9af894749 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -121,8 +121,8 @@ struct btrfs_device {
 	/* bytes used on the current transaction */
 	u64 commit_bytes_used;
 
-	/* for sending down flush barriers */
-	struct bio *flush_bio;
+	/* Bio used for flushing device barriers */
+	struct bio flush_bio;
 	struct completion flush_wait;
 
 	/* per-device scrub information */
-- 
2.30.2

Re: [PATCH 1/5] btrfs: simplify ->flush_bio handling

[Chaitanya Kulkarni]

On 4/5/22 23:12, Christoph Hellwig wrote:
> Use and embedded bios that is initialized when used instead of
> bio_kmalloc plus bio_reset.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: David Sterba <dsterba@suse.com>

Looks good.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck