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>
Parameters: <num devs> <chunk size> [<dev path> <offset>]+
<num devs>: Number of underlying devices.
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.
<dev path>: Full pathname to the underlying block-device, or a
"major:minor" device-number.
<offset>: Starting sector within the device.
/* The size of this target / num. stripes */
sector_t stripe_width;
/* The size of this target / num. stripes */
sector_t stripe_width;
- /* stripe chunk size */
- uint32_t chunk_shift;
- sector_t chunk_mask;
/* Needed for handling events */
struct dm_target *ti;
/* Needed for handling events */
struct dm_target *ti;
/*
* Construct a striped mapping.
/*
* 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)
{
*/
static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
- 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))) {
(chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
- ti->error = "Invalid chunk size";
+ ti->error = "Invalid chunk_size";
- 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;
ti->error = "Target length not divisible by "
"chunk size";
return -EINVAL;
ti->num_flush_requests = stripes;
ti->num_discard_requests = stripes;
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.
/*
* Get the stripe destinations.
static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
uint32_t *stripe, sector_t *result)
{
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);
if (sc->stripes_shift < 0)
*stripe = sector_div(chunk, sc->stripes);
chunk >>= sc->stripes_shift;
}
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,
}
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;
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)
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,
}
static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
case STATUSTYPE_TABLE:
DMEMIT("%d %llu", sc->stripes,
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);
for (i = 0; i < sc->stripes; i++)
DMEMIT(" %s %llu", sc->stripe[i].dev->name,
(unsigned long long)sc->stripe[i].physical_start);
struct queue_limits *limits)
{
struct stripe_c *sc = ti->private;
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);
blk_limits_io_min(limits, chunk_size);
blk_limits_io_opt(limits, chunk_size * sc->stripes);
static struct target_type stripe_target = {
.name = "striped",
static struct target_type stripe_target = {
.name = "striped",
.module = THIS_MODULE,
.ctr = stripe_ctr,
.dtr = stripe_dtr,
.module = THIS_MODULE,
.ctr = stripe_ctr,
.dtr = stripe_dtr,