Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit eb850de6 authored by Mike Snitzer's avatar Mike Snitzer Committed by Alasdair G Kergon
Browse files

dm stripe: support for non power of 2 chunksize 



Support non-power-of-2 chunk sizes with dm striping for proper alignment
of stripe IO on storage that has non-power-of-2 optimal IO sizes (e.g.
RAID6 10+2).

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 542f9038

Documentation/device-mapper/striped.txt

+2 −2
Original line number Diff line number Diff line
@@ -9,8 +9,8 @@ devices in parallel. 


Parameters: <num devs> <chunk size> [<dev path> <offset>]+

    <num devs>: Number of underlying devices.

    <chunk size>: Size of each chunk of data. Must be a power-of-2 and at

                  least as large as the system's PAGE_SIZE.

    <chunk size>: Size of each chunk of data. Must be at least as

                  large as the system's PAGE_SIZE.

    <dev path>: Full pathname to the underlying block-device, or a

                "major:minor" device-number.

    <offset>: Starting sector within the device.

drivers/md/dm-stripe.c

+19 −25
Original line number Diff line number Diff line
@@ -30,9 +30,7 @@ struct stripe_c { 
	/* The size of this target / num. stripes */

	sector_t stripe_width;



	/* stripe chunk size */

	uint32_t chunk_shift;

	sector_t chunk_mask;

	uint32_t chunk_size;



	/* Needed for handling events */

	struct dm_target *ti;
@@ -90,7 +88,7 @@ static int get_stripe(struct dm_target *ti, struct stripe_c *sc, 


/*

 * Construct a striped mapping.

 * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+

 * <number of stripes> <chunk size> [<dev_path> <offset>]+

 */

static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)

{
@@ -111,21 +109,14 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv) 
		return -EINVAL;

	}



	if (kstrtouint(argv[1], 10, &chunk_size)) {

		ti->error = "Invalid chunk_size";

		return -EINVAL;

	}



	/*

	 * chunk_size is a power of two

	 */

	if (!is_power_of_2(chunk_size) ||

	if (kstrtouint(argv[1], 10, &chunk_size) ||

	    (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {

		ti->error = "Invalid chunk size";

		ti->error = "Invalid chunk_size";

		return -EINVAL;

	}



	if (ti->len & (chunk_size - 1)) {

	width = ti->len;

	if (sector_div(width, chunk_size)) {

		ti->error = "Target length not divisible by "

		    "chunk size";

		return -EINVAL;
@@ -172,8 +163,7 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv) 
	ti->num_flush_requests = stripes;

	ti->num_discard_requests = stripes;



	sc->chunk_shift = ffs(chunk_size) - 1;

	sc->chunk_mask = ((sector_t) chunk_size) - 1;

	sc->chunk_size = chunk_size;



	/*

	 * Get the stripe destinations.
@@ -212,8 +202,8 @@ static void stripe_dtr(struct dm_target *ti) 
static void stripe_map_sector(struct stripe_c *sc, sector_t sector,

			      uint32_t *stripe, sector_t *result)

{

	sector_t offset = dm_target_offset(sc->ti, sector);

	sector_t chunk = offset >> sc->chunk_shift;

	sector_t chunk = dm_target_offset(sc->ti, sector);

	sector_t chunk_offset = sector_div(chunk, sc->chunk_size);



	if (sc->stripes_shift < 0)

		*stripe = sector_div(chunk, sc->stripes);
@@ -222,7 +212,7 @@ static void stripe_map_sector(struct stripe_c *sc, sector_t sector, 
		chunk >>= sc->stripes_shift;

	}



	*result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);

	*result = (chunk * sc->chunk_size) + chunk_offset;

}



static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
@@ -233,9 +223,13 @@ static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector, 
	stripe_map_sector(sc, sector, &stripe, result);

	if (stripe == target_stripe)

		return;

	*result &= ~sc->chunk_mask;			/* round down */



	/* round down */

	sector = *result;

	*result -= sector_div(sector, sc->chunk_size);



	if (target_stripe < stripe)

		*result += sc->chunk_mask + 1;		/* next chunk */

		*result += sc->chunk_size;		/* next chunk */

}



static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
@@ -320,7 +314,7 @@ static int stripe_status(struct dm_target *ti, 


	case STATUSTYPE_TABLE:

		DMEMIT("%d %llu", sc->stripes,

			(unsigned long long)sc->chunk_mask + 1);

			(unsigned long long)sc->chunk_size);

		for (i = 0; i < sc->stripes; i++)

			DMEMIT(" %s %llu", sc->stripe[i].dev->name,

			    (unsigned long long)sc->stripe[i].physical_start);
@@ -387,7 +381,7 @@ static void stripe_io_hints(struct dm_target *ti, 
			    struct queue_limits *limits)

{

	struct stripe_c *sc = ti->private;

	unsigned chunk_size = (sc->chunk_mask + 1) << 9;

	unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;



	blk_limits_io_min(limits, chunk_size);

	blk_limits_io_opt(limits, chunk_size * sc->stripes);
@@ -415,7 +409,7 @@ static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm, 


static struct target_type stripe_target = {

	.name   = "striped",

	.version = {1, 4, 0},

	.version = {1, 5, 0},

	.module = THIS_MODULE,

	.ctr    = stripe_ctr,

	.dtr    = stripe_dtr,