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dm: rename bio cloning functions
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Rename functions involved in splitting and cloning bios.

The sequence of functions is now:
  (1) __split_and_process* - entry point that selects the processing strategy
  (2) __send* - prepare the details for each bio needed and loop through them
  (3) __clone_and_map* - creates a clone and maps it

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Alasdair G Kergon committed Mar 1, 2013
1 parent 55a62ee commit 14fe594
Showing 1 changed file with 31 additions and 32 deletions.
63 changes: 31 additions & 32 deletions drivers/md/dm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1061,9 +1061,9 @@ static void clone_bio_integrity(struct bio *bio, struct bio *clone,
/*
* Creates a little bio that just does part of a bvec.
*/
static void split_bvec(struct dm_target_io *tio, struct bio *bio,
sector_t sector, unsigned short idx, unsigned int offset,
unsigned int len)
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;
Expand Down Expand Up @@ -1119,8 +1119,9 @@ static struct dm_target_io *alloc_tio(struct clone_info *ci,
return tio;
}

static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,
unsigned target_bio_nr, sector_t len)
static void __clone_and_map_simple_bio(struct clone_info *ci,
struct dm_target *ti,
unsigned target_bio_nr, sector_t len)
{
struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs, target_bio_nr);
struct bio *clone = &tio->clone;
Expand All @@ -1137,31 +1138,29 @@ static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,
__map_bio(tio);
}

static void __issue_target_bios(struct clone_info *ci, struct dm_target *ti,
unsigned num_bios, sector_t len)
static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
unsigned num_bios, sector_t len)
{
unsigned target_bio_nr;

for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++)
__issue_target_request(ci, ti, target_bio_nr, len);
__clone_and_map_simple_bio(ci, ti, target_bio_nr, len);
}

static int __clone_and_map_empty_flush(struct clone_info *ci)
static int __send_empty_flush(struct clone_info *ci)
{
unsigned target_nr = 0;
struct dm_target *ti;

BUG_ON(bio_has_data(ci->bio));
while ((ti = dm_table_get_target(ci->map, target_nr++)))
__issue_target_bios(ci, ti, ti->num_flush_bios, 0);
__send_duplicate_bios(ci, ti, ti->num_flush_bios, 0);

return 0;
}

/*
* Perform all io with a single clone.
*/
static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti)
static void __clone_and_map_data_bio(struct clone_info *ci,
struct dm_target *ti)
{
struct bio *bio = ci->bio;
struct dm_target_io *tio;
Expand Down Expand Up @@ -1192,9 +1191,9 @@ static bool is_split_required_for_discard(struct dm_target *ti)
return ti->split_discard_bios;
}

static int __clone_and_map_changing_extent_only(struct clone_info *ci,
get_num_bios_fn get_num_bios,
is_split_required_fn is_split_required)
static int __send_changing_extent_only(struct clone_info *ci,
get_num_bios_fn get_num_bios,
is_split_required_fn is_split_required)
{
struct dm_target *ti;
sector_t len;
Expand All @@ -1220,36 +1219,36 @@ static int __clone_and_map_changing_extent_only(struct clone_info *ci,
else
len = min(ci->sector_count, max_io_len(ci->sector, ti));

__issue_target_bios(ci, ti, num_bios, len);
__send_duplicate_bios(ci, ti, num_bios, len);

ci->sector += len;
} while (ci->sector_count -= len);

return 0;
}

static int __clone_and_map_discard(struct clone_info *ci)
static int __send_discard(struct clone_info *ci)
{
return __clone_and_map_changing_extent_only(ci, get_num_discard_bios,
is_split_required_for_discard);
return __send_changing_extent_only(ci, get_num_discard_bios,
is_split_required_for_discard);
}

static int __clone_and_map_write_same(struct clone_info *ci)
static int __send_write_same(struct clone_info *ci)
{
return __clone_and_map_changing_extent_only(ci, get_num_write_same_bios, NULL);
return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
}

static int __clone_and_map(struct clone_info *ci)
static int __split_and_process_non_flush(struct clone_info *ci)
{
struct bio *bio = ci->bio;
struct dm_target *ti;
sector_t len = 0, max;
struct dm_target_io *tio;

if (unlikely(bio->bi_rw & REQ_DISCARD))
return __clone_and_map_discard(ci);
return __send_discard(ci);
else if (unlikely(bio->bi_rw & REQ_WRITE_SAME))
return __clone_and_map_write_same(ci);
return __send_write_same(ci);

ti = dm_table_find_target(ci->map, ci->sector);
if (!dm_target_is_valid(ti))
Expand All @@ -1262,7 +1261,7 @@ static int __clone_and_map(struct clone_info *ci)
* Optimise for the simple case where we can do all of
* the remaining io with a single clone.
*/
__clone_and_map_simple(ci, ti);
__clone_and_map_data_bio(ci, ti);

} else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
/*
Expand Down Expand Up @@ -1311,8 +1310,8 @@ static int __clone_and_map(struct clone_info *ci)
len = min(remaining, max);

tio = alloc_tio(ci, ti, 1, 0);
split_bvec(tio, bio, ci->sector, ci->idx,
bv->bv_offset + offset, len);
clone_split_bio(tio, bio, ci->sector, ci->idx,
bv->bv_offset + offset, len);

__map_bio(tio);

Expand All @@ -1328,7 +1327,7 @@ static int __clone_and_map(struct clone_info *ci)
}

/*
* Split the bio into several clones and submit it to targets.
* Entry point to split a bio into clones and submit them to the targets.
*/
static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
{
Expand Down Expand Up @@ -1356,13 +1355,13 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
if (bio->bi_rw & REQ_FLUSH) {
ci.bio = &ci.md->flush_bio;
ci.sector_count = 0;
error = __clone_and_map_empty_flush(&ci);
error = __send_empty_flush(&ci);
/* dec_pending submits any data associated with flush */
} else {
ci.bio = bio;
ci.sector_count = bio_sectors(bio);
while (ci.sector_count && !error)
error = __clone_and_map(&ci);
error = __split_and_process_non_flush(&ci);
}

/* drop the extra reference count */
Expand Down

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