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Message-Id: <1364405992-28424-18-git-send-email-koverstreet@google.com>
Date: Wed, 27 Mar 2013 10:39:47 -0700
From: Kent Overstreet <koverstreet@...gle.com>
To: axboe@...nel.dk, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, dm-devel@...r.kernel.org
Cc: tj@...nel.org, neilb@...e.de,
Kent Overstreet <koverstreet@...gle.com>,
Alasdair Kergon <agk@...hat.com>, dm-devel@...hat.com
Subject: [PATCH 17/22] dm: Refactor for new bio cloning/splitting
We need to convert the dm code to the new bvec_iter primitives which
respect bi_bvec_done; they also allow us to drastically simplify dm's
bio splitting code.
Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
Cc: Alasdair Kergon <agk@...hat.com>
Cc: dm-devel@...hat.com
---
drivers/md/dm.c | 170 ++++++--------------------------------------------------
1 file changed, 18 insertions(+), 152 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 01a2451..d7ec2e6 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1014,7 +1014,6 @@ struct clone_info {
struct dm_io *io;
sector_t sector;
sector_t sector_count;
- unsigned short idx;
};
static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len)
@@ -1023,68 +1022,24 @@ static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len)
bio->bi_iter.bi_size = to_bytes(len);
}
-static void bio_setup_bv(struct bio *bio, unsigned short idx, unsigned short bv_count)
-{
- bio->bi_iter.bi_idx = idx;
- bio->bi_vcnt = idx + bv_count;
- bio->bi_flags &= ~(1 << BIO_SEG_VALID);
-}
-
-static void clone_bio_integrity(struct bio *bio, struct bio *clone,
- unsigned short idx, unsigned len, unsigned offset,
- unsigned trim)
-{
- if (!bio_integrity(bio))
- return;
-
- bio_integrity_clone(clone, bio, GFP_NOIO);
-
- if (trim)
- bio_integrity_trim(clone, bio_sector_offset(bio, idx, offset), len);
-}
-
-/*
- * Creates a little bio that just does part of a bvec.
- */
-static void clone_split_bio(struct dm_target_io *tio, struct bio *bio,
- sector_t sector, unsigned short idx,
- unsigned offset, unsigned len)
-{
- struct bio *clone = &tio->clone;
- struct bio_vec *bv = bio->bi_io_vec + idx;
-
- *clone->bi_io_vec = *bv;
-
- bio_setup_sector(clone, sector, len);
-
- clone->bi_bdev = bio->bi_bdev;
- clone->bi_rw = bio->bi_rw;
- clone->bi_vcnt = 1;
- clone->bi_io_vec->bv_offset = offset;
- clone->bi_io_vec->bv_len = clone->bi_iter.bi_size;
- clone->bi_flags |= 1 << BIO_CLONED;
-
- clone_bio_integrity(bio, clone, idx, len, offset, 1);
-}
-
/*
* Creates a bio that consists of range of complete bvecs.
*/
static void clone_bio(struct dm_target_io *tio, struct bio *bio,
- sector_t sector, unsigned short idx,
- unsigned short bv_count, unsigned len)
+ sector_t sector, unsigned len)
{
struct bio *clone = &tio->clone;
- unsigned trim = 0;
__bio_clone(clone, bio);
- bio_setup_sector(clone, sector, len);
- bio_setup_bv(clone, idx, bv_count);
- if (idx != bio->bi_iter.bi_idx ||
- clone->bi_iter.bi_size < bio->bi_iter.bi_size)
- trim = 1;
- clone_bio_integrity(bio, clone, idx, len, 0, trim);
+ if (bio_integrity(bio))
+ bio_integrity_clone(clone, bio, GFP_NOIO);
+
+ bio_advance(clone, (sector - clone->bi_iter.bi_sector) << 9);
+ bio->bi_iter.bi_size = len << 9;
+
+ if (bio_integrity(bio))
+ bio_integrity_trim(clone, 0, len);
}
static struct dm_target_io *alloc_tio(struct clone_info *ci,
@@ -1146,10 +1101,7 @@ static int __send_empty_flush(struct clone_info *ci)
}
static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
- sector_t sector, int nr_iovecs,
- unsigned short idx, unsigned short bv_count,
- unsigned offset, unsigned len,
- unsigned split_bvec)
+ sector_t sector, unsigned len)
{
struct bio *bio = ci->bio;
struct dm_target_io *tio;
@@ -1163,11 +1115,8 @@ static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti
num_target_bios = ti->num_write_bios(ti, bio);
for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
- tio = alloc_tio(ci, ti, nr_iovecs, target_bio_nr);
- if (split_bvec)
- clone_split_bio(tio, bio, sector, idx, offset, len);
- else
- clone_bio(tio, bio, sector, idx, bv_count, len);
+ tio = alloc_tio(ci, ti, 0, target_bio_nr);
+ clone_bio(tio, bio, sector, len);
__map_bio(tio);
}
}
@@ -1239,68 +1188,13 @@ static int __send_write_same(struct clone_info *ci)
}
/*
- * Find maximum number of sectors / bvecs we can process with a single bio.
- */
-static sector_t __len_within_target(struct clone_info *ci, sector_t max, int *idx)
-{
- struct bio *bio = ci->bio;
- sector_t bv_len, total_len = 0;
-
- for (*idx = ci->idx; max && (*idx < bio->bi_vcnt); (*idx)++) {
- bv_len = to_sector(bio->bi_io_vec[*idx].bv_len);
-
- if (bv_len > max)
- break;
-
- max -= bv_len;
- total_len += bv_len;
- }
-
- return total_len;
-}
-
-static int __split_bvec_across_targets(struct clone_info *ci,
- struct dm_target *ti, sector_t max)
-{
- struct bio *bio = ci->bio;
- struct bio_vec *bv = bio->bi_io_vec + ci->idx;
- sector_t remaining = to_sector(bv->bv_len);
- unsigned offset = 0;
- sector_t len;
-
- do {
- if (offset) {
- ti = dm_table_find_target(ci->map, ci->sector);
- if (!dm_target_is_valid(ti))
- return -EIO;
-
- max = max_io_len(ci->sector, ti);
- }
-
- len = min(remaining, max);
-
- __clone_and_map_data_bio(ci, ti, ci->sector, 1, ci->idx, 0,
- bv->bv_offset + offset, len, 1);
-
- ci->sector += len;
- ci->sector_count -= len;
- offset += to_bytes(len);
- } while (remaining -= len);
-
- ci->idx++;
-
- return 0;
-}
-
-/*
* Select the correct strategy for processing a non-flush bio.
*/
static int __split_and_process_non_flush(struct clone_info *ci)
{
struct bio *bio = ci->bio;
struct dm_target *ti;
- sector_t len, max;
- int idx;
+ unsigned len;
if (unlikely(bio->bi_rw & REQ_DISCARD))
return __send_discard(ci);
@@ -1311,41 +1205,14 @@ static int __split_and_process_non_flush(struct clone_info *ci)
if (!dm_target_is_valid(ti))
return -EIO;
- max = max_io_len(ci->sector, ti);
-
- /*
- * Optimise for the simple case where we can do all of
- * the remaining io with a single clone.
- */
- if (ci->sector_count <= max) {
- __clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
- ci->idx, bio->bi_vcnt - ci->idx, 0,
- ci->sector_count, 0);
- ci->sector_count = 0;
- return 0;
- }
-
- /*
- * There are some bvecs that don't span targets.
- * Do as many of these as possible.
- */
- if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
- len = __len_within_target(ci, max, &idx);
-
- __clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
- ci->idx, idx - ci->idx, 0, len, 0);
+ len = min_t(unsigned, max_io_len(ci->sector, ti), bio_sectors(bio));
- ci->sector += len;
- ci->sector_count -= len;
- ci->idx = idx;
+ __clone_and_map_data_bio(ci, ti, ci->sector, len);
- return 0;
- }
+ ci->sector += len;
+ ci->sector_count -= len;
- /*
- * Handle a bvec that must be split between two or more targets.
- */
- return __split_bvec_across_targets(ci, ti, max);
+ return 0;
}
/*
@@ -1370,7 +1237,6 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
ci.io->md = md;
spin_lock_init(&ci.io->endio_lock);
ci.sector = bio->bi_iter.bi_sector;
- ci.idx = bio->bi_iter.bi_idx;
start_io_acct(ci.io);
--
1.8.1.3
--
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