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authorMike Snitzer <snitzer@redhat.com>2012-07-27 15:08:01 +0100
committerAlasdair G Kergon <agk@redhat.com>2012-07-27 15:08:01 +0100
commiteb850de608cc22e0199b3797cd5c0076bae6cda0 (patch)
tree60cf311ac60af6fc5cae3b2cacca19ab8a74e7aa
parent542f90381422676544382d4071ba44a2de90a0c1 (diff)
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: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--Documentation/device-mapper/striped.txt4
-rw-r--r--drivers/md/dm-stripe.c44
2 files changed, 21 insertions, 27 deletions
diff --git a/Documentation/device-mapper/striped.txt b/Documentation/device-mapper/striped.txt
index 953fe1d68068..45f3b91ea4c3 100644
--- a/Documentation/device-mapper/striped.txt
+++ b/Documentation/device-mapper/striped.txt
@@ -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.
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 992c9d4c3bd9..9690daa11c83 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -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,