[PATCH v4 06/24] block: Change bio_split() to respect the current value of bi_idx

From: Kent Overstreet <hidden>
Date: 2012-10-15 20:24:04
Also in: dm-devel, lkml
Reply to: Kent Overstreet, 2012-10-15

In the current code bio_split() won't be seeing partially completed bios
so this doesn't change any behaviour, but this makes the code a bit
clearer as to what bio_split() actually requires.

The immediate purpose of the patch is removing unnecessary bi_idx
references, but the end goal is to allow partial completed bios to be
submitted, which along with immutable biovecs enables effecient bio
splitting.

Some of the callers were (double) checking that bios could be split, so
update their checks too.

Signed-off-by: Kent Overstreet <redacted>
CC: Jens Axboe <axboe@kernel.dk>
CC: Lars Ellenberg <redacted>
CC: Neil Brown <redacted>
CC: Martin K. Petersen <redacted>
---
 drivers/block/drbd/drbd_req.c | 6 +++---
 drivers/md/raid0.c            | 3 +--
 drivers/md/raid10.c           | 3 +--
 fs/bio-integrity.c            | 4 ++--
 fs/bio.c                      | 7 +++----
 5 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 47f55db..382ada7 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c

@@ -1155,11 +1155,11 @@ void drbd_make_request(struct request_queue *q, struct bio *bio)
 
 	/* can this bio be split generically?
 	 * Maybe add our own split-arbitrary-bios function. */
-	if (bio->bi_vcnt != 1 || bio->bi_idx != 0 || bio->bi_size > DRBD_MAX_BIO_SIZE) {
+	if (bio_segments(bio) != 1 || bio->bi_size > DRBD_MAX_BIO_SIZE) {
 		/* rather error out here than BUG in bio_split */
 		dev_err(DEV, "bio would need to, but cannot, be split: "
-		    "(vcnt=%u,idx=%u,size=%u,sector=%llu)\n",
-		    bio->bi_vcnt, bio->bi_idx, bio->bi_size,
+		    "(segments=%u,size=%u,sector=%llu)\n",
+		    bio_segments(bio), bio->bi_size,
 		    (unsigned long long)bio->bi_sector);
 		bio_endio(bio, -EINVAL);
 	} else {

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 89016cb..769b3cb 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c

@@ -510,8 +510,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 		sector_t sector = bio->bi_sector;
 		struct bio_pair *bp;
 		/* Sanity check -- queue functions should prevent this happening */
-		if (bio->bi_vcnt != 1 ||
-		    bio->bi_idx != 0)
+		if (bio_segments(bio) != 1)
 			goto bad_map;
 		/* This is a one page bio that upper layers
 		 * refuse to split for us, so we need to split it.

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 9715aaf..bbd08f5 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c

@@ -1081,8 +1081,7 @@ static void make_request(struct mddev *mddev, struct bio * bio)
 			 || conf->prev.near_copies < conf->prev.raid_disks))) {
 		struct bio_pair *bp;
 		/* Sanity check -- queue functions should prevent this happening */
-		if (bio->bi_vcnt != 1 ||
-		    bio->bi_idx != 0)
+		if (bio_segments(bio) != 1)
 			goto bad_map;
 		/* This is a one page bio that upper layers
 		 * refuse to split for us, so we need to split it.

diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
index 8c4c604..ca7b02d 100644
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c

@@ -661,8 +661,8 @@ void bio_integrity_split(struct bio *bio, struct bio_pair *bp, int sectors)
 	bp->bio1.bi_integrity = &bp->bip1;
 	bp->bio2.bi_integrity = &bp->bip2;
 
-	bp->iv1 = bip->bip_vec[0];
-	bp->iv2 = bip->bip_vec[0];
+	bp->iv1 = bip->bip_vec[bip->bip_idx];
+	bp->iv2 = bip->bip_vec[bip->bip_idx];
 
 	bp->bip1.bip_vec = &bp->iv1;
 	bp->bip2.bip_vec = &bp->iv2;

diff --git a/fs/bio.c b/fs/bio.c
index dc3452e..4ae3382 100644
--- a/fs/bio.c
+++ b/fs/bio.c

@@ -1616,8 +1616,7 @@ struct bio_pair *bio_split(struct bio *bi, int first_sectors)
 	trace_block_split(bdev_get_queue(bi->bi_bdev), bi,
 				bi->bi_sector + first_sectors);
 
-	BUG_ON(bi->bi_vcnt != 1 && bi->bi_vcnt != 0);
-	BUG_ON(bi->bi_idx != 0);
+	BUG_ON(bio_segments(bi) > 1);
 	atomic_set(&bp->cnt, 3);
 	bp->error = 0;
 	bp->bio1 = *bi;

@@ -1627,8 +1626,8 @@ struct bio_pair *bio_split(struct bio *bi, int first_sectors)
 	bp->bio1.bi_size = first_sectors << 9;
 
 	if (bi->bi_vcnt != 0) {
-		bp->bv1 = bi->bi_io_vec[0];
-		bp->bv2 = bi->bi_io_vec[0];
+		bp->bv1 = *bio_iovec(bi);
+		bp->bv2 = *bio_iovec(bi);
 
 		if (bio_is_rw(bi)) {
 			bp->bv2.bv_offset += first_sectors << 9;

-- 
1.7.12

Kent Overstreet · 2012-10-15
[PATCH v4 02/24] block: Refactor blk_update_request() · Kent Overstreet · 2012-10-15
[PATCH v4 01/24] block: Add bio_advance() · Kent Overstreet · 2012-10-15
[PATCH v4 07/24] block: Remove bi_idx references · Kent Overstreet · 2012-10-15
[PATCH v4 10/24] raid10: Use bio_reset() · Kent Overstreet · 2012-10-15
[PATCH v4 12/24] raid5: use bio_reset() · Kent Overstreet · 2012-10-15
[PATCH v4 15/24] pktcdvd: use bio_copy_data() · Kent Overstreet · 2012-10-15
[PATCH v4 20/24] block: Convert some code to bio_for_each_segment_all() · Kent Overstreet · 2012-10-15
[PATCH v4 21/24] block: Add bio_alloc_pages() · Kent Overstreet · 2012-10-15
[PATCH v4 1/2] block: Reorder struct bio_set · Kent Overstreet · 2012-10-15
Re: [PATCH v4 1/2] block: Reorder struct bio_set · Tejun Heo · 2012-10-19
[PATCH v4 2/2] block: Convert integrity to bvec_alloc_bs() · Kent Overstreet · 2012-10-15
Re: [PATCH v4 2/2] block: Convert integrity to bvec_alloc_bs() · Vivek Goyal · 2012-10-19
[PATCH v2 04/26] md: Convert md_trim_bio() to use bio_advance() · Kent Overstreet · 2012-10-15
[PATCH v2 10/26] block: Add submit_bio_wait(), remove from md · Kent Overstreet · 2012-10-15
[PATCH v2 09/26] block: Remove some unnecessary bi_vcnt usage · Kent Overstreet · 2012-10-15
[PATCH v2 08/26] block: Remove bi_idx references · Kent Overstreet · 2012-10-15
[PATCH v2 15/26] block: Add bio_copy_data() · Kent Overstreet · 2012-10-15
[PATCH v2 20/26] block: Add bio_for_each_segment_all() · Kent Overstreet · 2012-10-15
[PATCH v2 19/26] bounce: Refactor __blk_queue_bounce to not use bi_io_vec · Kent Overstreet · 2012-10-15
[PATCH v2 25/26] bio-integrity: Add explicit field for owner of bip_buf · Kent Overstreet · 2012-10-15
[PATCH v2 24/26] block: Add an explicit bio flag for bios that own their bvec · Kent Overstreet · 2012-10-15
[PATCH v2 26/26] block: Add BIO_SUBMITTED flag, kill BIO_CLONED · Kent Overstreet · 2012-10-15
[PATCH v2 23/26] raid1: use bio_alloc_pages() · Kent Overstreet · 2012-10-15
[PATCH v2 22/26] block: Add bio_alloc_pages() · Kent Overstreet · 2012-10-15
[PATCH v2 21/26] block: Convert some code to bio_for_each_segment_all() · Kent Overstreet · 2012-10-15
[PATCH v2 18/26] raid1: use bio_copy_data() · Kent Overstreet · 2012-10-15
[PATCH v2 17/26] pktcdvd: Use bio_reset() in disabled code to kill bi_idx usage · Kent Overstreet · 2012-10-15
[PATCH v2 16/26] pktcdvd: use bio_copy_data() · Kent Overstreet · 2012-10-15
[PATCH v2 14/26] raid1: Refactor narrow_write_error() to not use bi_idx · Kent Overstreet · 2012-10-15
[PATCH v2 13/26] raid5: use bio_reset() · Kent Overstreet · 2012-10-15
[PATCH v2 12/26] raid1: use bio_reset() · Kent Overstreet · 2012-10-15
[PATCH v2 11/26] raid10: Use bio_reset() · Kent Overstreet · 2012-10-15
[PATCH v2 07/26] block: Don't use bi_idx in bio_split() or require it to be 0 · Kent Overstreet · 2012-10-15
[PATCH v2 06/26] block: Use bio_sectors() more consistently · Kent Overstreet · 2012-10-15
[PATCH v2 05/26] block: Add bio_end() · Kent Overstreet · 2012-10-15
[PATCH v2 03/26] block: Refactor blk_update_request() · Kent Overstreet · 2012-10-15
[PATCH v2 02/26] block: Add bio_advance() · Kent Overstreet · 2012-10-15
[PATCH v2 01/26] block: Convert integrity to bvec_alloc_bs(), and a bugfix · Kent Overstreet · 2012-10-15
Re: [PATCH v2 01/26] block: Convert integrity to bvec_alloc_bs(), and a bugfix · Tejun Heo · 2012-10-19
Re: [PATCH v2 01/26] block: Convert integrity to bvec_alloc_bs(), and a bugfix · Tejun Heo · 2012-10-19
[PATCH v2 00/26] Prep work for immutable bio vecs · Kent Overstreet · 2012-10-15
[PATCH v4 1/2] block: Fix a buffer overrun in bio_integrity_split() · Kent Overstreet · 2012-10-15
Re: [PATCH v4 1/2] block: Fix a buffer overrun in bio_integrity_split() · Tejun Heo · 2012-10-19
Re: [PATCH v4 1/2] block: Fix a buffer overrun in bio_integrity_split() · Vivek Goyal · 2012-10-22
[PATCH v4 2/2] block: Avoid deadlocks with bio allocation by stacking drivers · Kent Overstreet · 2012-10-15
[PATCH v4 24/24] block: Add BIO_SUBMITTED flag, kill BIO_CLONED · Kent Overstreet · 2012-10-15
[PATCH v4 23/24] bio-integrity: Add explicit field for owner of bip_buf · Kent Overstreet · 2012-10-15
[PATCH v4 22/24] block: Add an explicit bio flag for bios that own their bvec · Kent Overstreet · 2012-10-15
[PATCH v4 19/24] block: Add bio_for_each_segment_all() · Kent Overstreet · 2012-10-15
[PATCH v4 18/24] bounce: Refactor __blk_queue_bounce to not use bi_io_vec · Kent Overstreet · 2012-10-15
[PATCH v4 17/24] raid1: use bio_copy_data() · Kent Overstreet · 2012-10-15
[PATCH v4 16/24] pktcdvd: Use bio_reset() in disabled code to kill bi_idx usage · Kent Overstreet · 2012-10-15
[PATCH v4 14/24] block: Add bio_copy_data() · Kent Overstreet · 2012-10-15
[PATCH v4 13/24] raid1: Refactor narrow_write_error() to not use bi_idx · Kent Overstreet · 2012-10-15
[PATCH v4 11/24] raid1: use bio_reset() · Kent Overstreet · 2012-10-15
[PATCH v4 09/24] block: Add submit_bio_wait(), remove from md · Kent Overstreet · 2012-10-15
[PATCH v4 08/24] block: Remove some unnecessary bi_vcnt usage · Kent Overstreet · 2012-10-15
RE: [PATCH v4 08/24] block: Remove some unnecessary bi_vcnt usage · Reddy, Sreekanth · 2012-11-06
RE: [PATCH v4 08/24] block: Remove some unnecessary bi_vcnt usage · Reddy, Sreekanth · 2012-11-07
[PATCH v4 06/24] block: Change bio_split() to respect the current value of bi_idx · Kent Overstreet · 2012-10-15
[PATCH v4 05/24] block: Use bio_sectors() more consistently · Kent Overstreet · 2012-10-15
Re: [PATCH v4 05/24] block: Use bio_sectors() more consistently · Ed Cashin · 2012-10-16
[PATCH v4 04/24] block: Add bio_end_sector() · Kent Overstreet · 2012-10-15
[PATCH v4 03/24] md: Convert md_trim_bio() to use bio_advance() · Kent Overstreet · 2012-10-15
Tejun Heo · 2012-10-19
Mike Snitzer · 2012-10-19
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