block: Change bio_split() to respect the current value of bi_idx

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 <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Lars Ellenberg <drbd-dev@lists.linbit.com>
CC: Neil Brown <neilb@suse.de>
CC: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 23a38afec3518738f7125c755d8b910e1f0e24a1..fcf65e512cf51a02413ae4439e72ce7ab6675159 100644 (file)
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -527,8 +527,7 @@ 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_vcnt != 0) ||
-                   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 5ee14ab16a058714ca03f82d5d05c75046e16fee..2e29df960bf57d2f78da82ce5a4e61eb4ab0c41e 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1175,8 +1175,7 @@ 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_vcnt != 0) ||
-                   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 8c4c604c840df76309d325c301c50dc00b818bba..ca7b02dbf09d62d731faf3810033c14bb7f4339e 100644 (file)
--- 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 7edc08d2246cf03548cce3b8b72d863d4d16269f..f1b4c16510897823b3e6f0aa784fe5f9a56db396 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1620,8 +1620,7 @@ 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;
@@ -1631,8 +1630,8 @@ 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;