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Commit 56a67df7 authored by Mike Snitzer's avatar Mike Snitzer Committed by Alasdair G Kergon
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dm: factor out max_io_len_target_boundary 



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: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 06a426ce

drivers/md/dm.c

+18 −8
Original line number Diff line number Diff line
@@ -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 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 offset = sector - ti->begin;

	sector_t len = ti->len - offset;

	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)

include/linux/device-mapper.h

+6 −0
Original line number Diff line number Diff line
@@ -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);