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dm: factor out max_io_len_target_boundary

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Split max_io_len_target_boundary out of max_io_len so that the discard
support can make use of it without duplicating max_io_len code.

Avoiding max_io_len's split_io logic enables DM's discard support to
submit the entire discard request to a target.  But discards must still
be split on target boundaries.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mike Snitzer 2010-08-12 04:14:10 +01:00 committed by Alasdair G Kergon
parent 06a426cee9
commit 56a67df766
2 changed files with 24 additions and 8 deletions
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26
drivers/md/dm.c
View File

@ -1030,17 +1030,27 @@ static void end_clone_request(struct request *clone, int error)
dm_complete_request(clone, error);
}
static sector_t max_io_len(struct mapped_device *md,
sector_t sector, struct dm_target *ti)
/*
* Return maximum size of I/O possible at the supplied sector up to the current
* target boundary.
*/
static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
{
sector_t offset = sector - ti->begin;
sector_t len = ti->len - offset;
sector_t target_offset = dm_target_offset(ti, sector);
return ti->len - target_offset;
}
static sector_t max_io_len(sector_t sector, struct dm_target *ti)
{
sector_t len = max_io_len_target_boundary(sector, ti);
/*
* Does the target need to split even further ?
*/
if (ti->split_io) {
sector_t boundary;
sector_t offset = dm_target_offset(ti, sector);
boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
- offset;
if (len > boundary)
@ -1258,7 +1268,7 @@ static int __clone_and_map_discard(struct clone_info *ci)
if (!ti->num_discard_requests)
return -EOPNOTSUPP;
max = max_io_len(ci->md, ci->sector, ti);
max = max_io_len(ci->sector, ti);
if (ci->sector_count > max)
/*
@ -1290,7 +1300,7 @@ static int __clone_and_map(struct clone_info *ci)
if (!dm_target_is_valid(ti))
return -EIO;
max = max_io_len(ci->md, ci->sector, ti);
max = max_io_len(ci->sector, ti);
if (ci->sector_count <= max) {
/*
@ -1341,7 +1351,7 @@ static int __clone_and_map(struct clone_info *ci)
if (!dm_target_is_valid(ti))
return -EIO;
max = max_io_len(ci->md, ci->sector, ti);
max = max_io_len(ci->sector, ti);
}
len = min(remaining, max);
@ -1428,7 +1438,7 @@ static int dm_merge_bvec(struct request_queue *q,
/*
* Find maximum amount of I/O that won't need splitting
*/
max_sectors = min(max_io_len(md, bvm->bi_sector, ti),
max_sectors = min(max_io_len(bvm->bi_sector, ti),
(sector_t) BIO_MAX_SECTORS);
max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
if (max_size < 0)

6
include/linux/device-mapper.h
View File

@ -398,6 +398,12 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
#define dm_array_too_big(fixed, obj, num) \
((num) > (UINT_MAX - (fixed)) / (obj))
/*
* Sector offset taken relative to the start of the target instead of
* relative to the start of the device.
*/
#define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
static inline sector_t to_sector(unsigned long n)
{
return (n >> SECTOR_SHIFT);