dm thin: support for non power of 2 pool blocksize
Non power of 2 blocksize support is needed to properly align thinp IO
on storage that has non power of 2 optimal IO sizes (e.g. RAID6 10+2).
Use sector_div to support non power of 2 blocksize for the pool's
data device. This provides comparable performance to the power of 2
math that was performed until now (as tested on modern x86_64 hardware).
The kernel currently assumes that limits->discard_granularity is a power
of two so the thin target only enables discard support if the block
size is a power of two.
Eliminate pool structure's 'block_shift', 'offset_mask' and
remaining 4 byte holes.
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>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 350bcf4..f21d318 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -510,10 +510,8 @@
struct block_device *md_dev;
struct dm_pool_metadata *pmd;
- uint32_t sectors_per_block;
- unsigned block_shift;
- dm_block_t offset_mask;
dm_block_t low_water_blocks;
+ uint32_t sectors_per_block;
struct pool_features pf;
unsigned low_water_triggered:1; /* A dm event has been sent */
@@ -526,8 +524,8 @@
struct work_struct worker;
struct delayed_work waker;
- unsigned ref_count;
unsigned long last_commit_jiffies;
+ unsigned ref_count;
spinlock_t lock;
struct bio_list deferred_bios;
@@ -679,16 +677,21 @@
static dm_block_t get_bio_block(struct thin_c *tc, struct bio *bio)
{
- return bio->bi_sector >> tc->pool->block_shift;
+ sector_t block_nr = bio->bi_sector;
+
+ (void) sector_div(block_nr, tc->pool->sectors_per_block);
+
+ return block_nr;
}
static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block)
{
struct pool *pool = tc->pool;
+ sector_t bi_sector = bio->bi_sector;
bio->bi_bdev = tc->pool_dev->bdev;
- bio->bi_sector = (block << pool->block_shift) +
- (bio->bi_sector & pool->offset_mask);
+ bio->bi_sector = (block * pool->sectors_per_block) +
+ sector_div(bi_sector, pool->sectors_per_block);
}
static void remap_to_origin(struct thin_c *tc, struct bio *bio)
@@ -933,9 +936,10 @@
*/
static int io_overlaps_block(struct pool *pool, struct bio *bio)
{
- return !(bio->bi_sector & pool->offset_mask) &&
- (bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT));
+ sector_t bi_sector = bio->bi_sector;
+ return !sector_div(bi_sector, pool->sectors_per_block) &&
+ (bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT));
}
static int io_overwrites_block(struct pool *pool, struct bio *bio)
@@ -1239,8 +1243,8 @@
* part of the discard that is in a subsequent
* block.
*/
- sector_t offset = bio->bi_sector - (block << pool->block_shift);
- unsigned remaining = (pool->sectors_per_block - offset) << 9;
+ sector_t offset = bio->bi_sector - (block * pool->sectors_per_block);
+ unsigned remaining = (pool->sectors_per_block - offset) << SECTOR_SHIFT;
bio->bi_size = min(bio->bi_size, remaining);
cell_release_singleton(cell, bio);
@@ -1722,8 +1726,6 @@
pool->pmd = pmd;
pool->sectors_per_block = block_size;
- pool->block_shift = ffs(block_size) - 1;
- pool->offset_mask = block_size - 1;
pool->low_water_blocks = 0;
pool_features_init(&pool->pf);
pool->prison = prison_create(PRISON_CELLS);
@@ -1971,7 +1973,7 @@
if (kstrtoul(argv[2], 10, &block_size) || !block_size ||
block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
- !is_power_of_2(block_size)) {
+ block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
ti->error = "Invalid block size";
r = -EINVAL;
goto out;
@@ -2018,6 +2020,15 @@
goto out_flags_changed;
}
+ /*
+ * The block layer requires discard_granularity to be a power of 2.
+ */
+ if (pf.discard_enabled && !is_power_of_2(block_size)) {
+ ti->error = "Discard support must be disabled when the block size is not a power of 2";
+ r = -EINVAL;
+ goto out_flags_changed;
+ }
+
pt->pool = pool;
pt->ti = ti;
pt->metadata_dev = metadata_dev;
@@ -2097,7 +2108,8 @@
int r;
struct pool_c *pt = ti->private;
struct pool *pool = pt->pool;
- dm_block_t data_size, sb_data_size;
+ sector_t data_size = ti->len;
+ dm_block_t sb_data_size;
/*
* Take control of the pool object.
@@ -2106,7 +2118,8 @@
if (r)
return r;
- data_size = ti->len >> pool->block_shift;
+ (void) sector_div(data_size, pool->sectors_per_block);
+
r = dm_pool_get_data_dev_size(pool->pmd, &sb_data_size);
if (r) {
DMERR("failed to retrieve data device size");
@@ -2115,7 +2128,7 @@
if (data_size < sb_data_size) {
DMERR("pool target too small, is %llu blocks (expected %llu)",
- data_size, sb_data_size);
+ (unsigned long long)data_size, sb_data_size);
return -EINVAL;
} else if (data_size > sb_data_size) {
@@ -2764,19 +2777,21 @@
static int thin_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
- dm_block_t blocks;
+ sector_t blocks;
struct thin_c *tc = ti->private;
+ struct pool *pool = tc->pool;
/*
* We can't call dm_pool_get_data_dev_size() since that blocks. So
* we follow a more convoluted path through to the pool's target.
*/
- if (!tc->pool->ti)
+ if (!pool->ti)
return 0; /* nothing is bound */
- blocks = tc->pool->ti->len >> tc->pool->block_shift;
+ blocks = pool->ti->len;
+ (void) sector_div(blocks, pool->sectors_per_block);
if (blocks)
- return fn(ti, tc->pool_dev, 0, tc->pool->sectors_per_block * blocks, data);
+ return fn(ti, tc->pool_dev, 0, pool->sectors_per_block * blocks, data);
return 0;
}
@@ -2793,7 +2808,7 @@
static struct target_type thin_target = {
.name = "thin",
- .version = {1, 1, 0},
+ .version = {1, 2, 0},
.module = THIS_MODULE,
.ctr = thin_ctr,
.dtr = thin_dtr,