On 2022/9/1 15:42, Christoph Hellwig wrote:
bio_split_rw can be used by file systems to split and incoming write
bio into multiple bios fitting the hardware limit for use as ZONE_APPEND
bios. Export it for initial use in btrfs.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-merge.c | 3 ++-
include/linux/bio.h | 4 ++++
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index ff04e9290715a..e68295462977b 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -267,7 +267,7 @@ static bool bvec_split_segs(struct queue_limits *lim, const struct bio_vec *bv,
* responsible for ensuring that @bs is only destroyed after processing of the
* split bio has finished.
*/
-static struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
+struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
I found the queue_limits structure pretty scary, while we only have very
limited members used in this case:
- lim->virt_boundary_mask
Used in bvec_gap_to_prev()
- lim->max_segments
- lim->seg_boundary_mask
- lim->max_segment_size
Used in bvec_split_segs()
- lim->logical_block_size
Not familiar with block layer, thus I'm wondering do btrfs really need a
full queue_limits structure to call bio_split_rw().
Or can we have a simplified wrapper?
IIRC inside btrfs we only need two cases for bio split:
- Split for stripe boundary
- Split for OE/zoned boundary
Thanks,
Qu
unsigned *segs, struct bio_set *bs, unsigned max_bytes)
{
struct bio_vec bv, bvprv, *bvprvp = NULL;
@@ -317,6 +317,7 @@ static struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
bio_clear_polled(bio);
return bio_split(bio, bytes >> SECTOR_SHIFT, GFP_NOIO, bs);
}
+EXPORT_SYMBOL_GPL(bio_split_rw);
/**
* __bio_split_to_limits - split a bio to fit the queue limits
diff --git a/include/linux/bio.h b/include/linux/bio.h
index ca22b06700a94..46890f8235401 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -12,6 +12,8 @@
#define BIO_MAX_VECS 256U
+struct queue_limits;
+
static inline unsigned int bio_max_segs(unsigned int nr_segs)
{
return min(nr_segs, BIO_MAX_VECS);
@@ -375,6 +377,8 @@ static inline void bip_set_seed(struct bio_integrity_payload *bip,
void bio_trim(struct bio *bio, sector_t offset, sector_t size);
extern struct bio *bio_split(struct bio *bio, int sectors,
gfp_t gfp, struct bio_set *bs);
+struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
+ unsigned *segs, struct bio_set *bs, unsigned max_bytes);
/**
* bio_next_split - get next @sectors from a bio, splitting if necessary
