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Commit 67e2e2b281812b5caf4923a38aadc6b89e34f064

Authored by Joe Thornber
Committed by Alasdair G Kergon
1 parent 104655fd4d
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

dm thin: add pool target flags to control discard 

Add dm thin target arguments to control discard support.

ignore_discard: Disables discard support

no_discard_passdown: Don't pass discards down to the underlying data
device, but just remove the mapping within the thin provisioning target.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

Showing 2 changed files with 115 additions and 28 deletions Side-by-side Diff

Documentation/device-mapper/thin-provisioning.txt
Diff comments   View file @ 67e2e2b
... ... @@ -223,7 +223,13 @@
223 223 <low water mark (blocks)> [<number of feature args> [<arg>]*]
224 224  
225 225 Optional feature arguments:
226   - - 'skip_block_zeroing': skips the zeroing of newly-provisioned blocks.
  226 +
  227 + skip_block_zeroing: Skip the zeroing of newly-provisioned blocks.
  228 +
  229 + ignore_discard: Disable discard support.
  230 +
  231 + no_discard_passdown: Don't pass discards down to the underlying
  232 + data device, but just remove the mapping.
227 233  
228 234 Data block size must be between 64KB (128 sectors) and 1GB
229 235 (2097152 sectors) inclusive.
drivers/md/dm-thin.c
Diff comments   View file @ 67e2e2b
... ... @@ -489,6 +489,13 @@
489 489 * devices.
490 490 */
491 491 struct new_mapping;
  492 +
  493 +struct pool_features {
  494 + unsigned zero_new_blocks:1;
  495 + unsigned discard_enabled:1;
  496 + unsigned discard_passdown:1;
  497 +};
  498 +
492 499 struct pool {
493 500 struct list_head list;
494 501 struct dm_target *ti; /* Only set if a pool target is bound */
... ... @@ -502,7 +509,7 @@
502 509 dm_block_t offset_mask;
503 510 dm_block_t low_water_blocks;
504 511  
505   - unsigned zero_new_blocks:1;
  512 + struct pool_features pf;
506 513 unsigned low_water_triggered:1; /* A dm event has been sent */
507 514 unsigned no_free_space:1; /* A -ENOSPC warning has been issued */
508 515  
... ... @@ -543,7 +550,7 @@
543 550 struct dm_target_callbacks callbacks;
544 551  
545 552 dm_block_t low_water_blocks;
546   - unsigned zero_new_blocks:1;
  553 + struct pool_features pf;
547 554 };
548 555  
549 556 /*
... ... @@ -1051,7 +1058,7 @@
1051 1058 * zeroing pre-existing data, we can issue the bio immediately.
1052 1059 * Otherwise we use kcopyd to zero the data first.
1053 1060 */
1054   - if (!pool->zero_new_blocks)
  1061 + if (!pool->pf.zero_new_blocks)
1055 1062 process_prepared_mapping(m);
1056 1063  
1057 1064 else if (io_overwrites_block(pool, bio)) {
... ... @@ -1202,7 +1209,7 @@
1202 1209 */
1203 1210 m = get_next_mapping(pool);
1204 1211 m->tc = tc;
1205   - m->pass_discard = !lookup_result.shared;
  1212 + m->pass_discard = (!lookup_result.shared) & pool->pf.discard_passdown;
1206 1213 m->virt_block = block;
1207 1214 m->data_block = lookup_result.block;
1208 1215 m->cell = cell;
... ... @@ -1617,7 +1624,7 @@
1617 1624  
1618 1625 pool->ti = ti;
1619 1626 pool->low_water_blocks = pt->low_water_blocks;
1620   - pool->zero_new_blocks = pt->zero_new_blocks;
  1627 + pool->pf = pt->pf;
1621 1628  
1622 1629 return 0;
1623 1630 }
... ... @@ -1631,6 +1638,14 @@
1631 1638 /*----------------------------------------------------------------
1632 1639 * Pool creation
1633 1640 *--------------------------------------------------------------*/
  1641 +/* Initialize pool features. */
  1642 +static void pool_features_init(struct pool_features *pf)
  1643 +{
  1644 + pf->zero_new_blocks = 1;
  1645 + pf->discard_enabled = 1;
  1646 + pf->discard_passdown = 1;
  1647 +}
  1648 +
1634 1649 static void __pool_destroy(struct pool *pool)
1635 1650 {
1636 1651 __pool_table_remove(pool);
... ... @@ -1678,7 +1693,7 @@
1678 1693 pool->block_shift = ffs(block_size) - 1;
1679 1694 pool->offset_mask = block_size - 1;
1680 1695 pool->low_water_blocks = 0;
1681   - pool->zero_new_blocks = 1;
  1696 + pool_features_init(&pool->pf);
1682 1697 pool->prison = prison_create(PRISON_CELLS);
1683 1698 if (!pool->prison) {
1684 1699 *error = "Error creating pool's bio prison";
... ... @@ -1775,7 +1790,8 @@
1775 1790  
1776 1791 static struct pool *__pool_find(struct mapped_device *pool_md,
1777 1792 struct block_device *metadata_dev,
1778   - unsigned long block_size, char **error)
  1793 + unsigned long block_size, char **error,
  1794 + int *created)
1779 1795 {
1780 1796 struct pool *pool = __pool_table_lookup_metadata_dev(metadata_dev);
1781 1797  
1782 1798  
... ... @@ -1791,8 +1807,10 @@
1791 1807 return ERR_PTR(-EINVAL);
1792 1808 __pool_inc(pool);
1793 1809  
1794   - } else
  1810 + } else {
1795 1811 pool = pool_create(pool_md, metadata_dev, block_size, error);
  1812 + *created = 1;
  1813 + }
1796 1814 }
1797 1815  
1798 1816 return pool;
... ... @@ -1816,10 +1834,6 @@
1816 1834 mutex_unlock(&dm_thin_pool_table.mutex);
1817 1835 }
1818 1836  
1819   -struct pool_features {
1820   - unsigned zero_new_blocks:1;
1821   -};
1822   -
1823 1837 static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
1824 1838 struct dm_target *ti)
1825 1839 {
... ... @@ -1828,7 +1842,7 @@
1828 1842 const char *arg_name;
1829 1843  
1830 1844 static struct dm_arg _args[] = {
1831   - {0, 1, "Invalid number of pool feature arguments"},
  1845 + {0, 3, "Invalid number of pool feature arguments"},
1832 1846 };
1833 1847  
1834 1848 /*
... ... @@ -1848,6 +1862,12 @@
1848 1862 if (!strcasecmp(arg_name, "skip_block_zeroing")) {
1849 1863 pf->zero_new_blocks = 0;
1850 1864 continue;
  1865 + } else if (!strcasecmp(arg_name, "ignore_discard")) {
  1866 + pf->discard_enabled = 0;
  1867 + continue;
  1868 + } else if (!strcasecmp(arg_name, "no_discard_passdown")) {
  1869 + pf->discard_passdown = 0;
  1870 + continue;
1851 1871 }
1852 1872  
1853 1873 ti->error = "Unrecognised pool feature requested";
1854 1874  
... ... @@ -1865,10 +1885,12 @@
1865 1885 *
1866 1886 * Optional feature arguments are:
1867 1887 * skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
  1888 + * ignore_discard: disable discard
  1889 + * no_discard_passdown: don't pass discards down to the data device
1868 1890 */
1869 1891 static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
1870 1892 {
1871   - int r;
  1893 + int r, pool_created = 0;
1872 1894 struct pool_c *pt;
1873 1895 struct pool *pool;
1874 1896 struct pool_features pf;
... ... @@ -1928,8 +1950,7 @@
1928 1950 /*
1929 1951 * Set default pool features.
1930 1952 */
1931   - memset(&pf, 0, sizeof(pf));
1932   - pf.zero_new_blocks = 1;
  1953 + pool_features_init(&pf);
1933 1954  
1934 1955 dm_consume_args(&as, 4);
1935 1956 r = parse_pool_features(&as, &pf, ti);
1936 1957  
1937 1958  
1938 1959  
... ... @@ -1943,21 +1964,58 @@
1943 1964 }
1944 1965  
1945 1966 pool = __pool_find(dm_table_get_md(ti->table), metadata_dev->bdev,
1946   - block_size, &ti->error);
  1967 + block_size, &ti->error, &pool_created);
1947 1968 if (IS_ERR(pool)) {
1948 1969 r = PTR_ERR(pool);
1949 1970 goto out_free_pt;
1950 1971 }
1951 1972  
  1973 + /*
  1974 + * 'pool_created' reflects whether this is the first table load.
  1975 + * Top level discard support is not allowed to be changed after
  1976 + * initial load. This would require a pool reload to trigger thin
  1977 + * device changes.
  1978 + */
  1979 + if (!pool_created && pf.discard_enabled != pool->pf.discard_enabled) {
  1980 + ti->error = "Discard support cannot be disabled once enabled";
  1981 + r = -EINVAL;
  1982 + goto out_flags_changed;
  1983 + }
  1984 +
  1985 + /*
  1986 + * If discard_passdown was enabled verify that the data device
  1987 + * supports discards. Disable discard_passdown if not; otherwise
  1988 + * -EOPNOTSUPP will be returned.
  1989 + */
  1990 + if (pf.discard_passdown) {
  1991 + struct request_queue *q = bdev_get_queue(data_dev->bdev);
  1992 + if (!q || !blk_queue_discard(q)) {
  1993 + DMWARN("Discard unsupported by data device: Disabling discard passdown.");
  1994 + pf.discard_passdown = 0;
  1995 + }
  1996 + }
  1997 +
1952 1998 pt->pool = pool;
1953 1999 pt->ti = ti;
1954 2000 pt->metadata_dev = metadata_dev;
1955 2001 pt->data_dev = data_dev;
1956 2002 pt->low_water_blocks = low_water_blocks;
1957   - pt->zero_new_blocks = pf.zero_new_blocks;
  2003 + pt->pf = pf;
1958 2004 ti->num_flush_requests = 1;
1959   - ti->num_discard_requests = 1;
1960   - ti->discards_supported = 1;
  2005 + /*
  2006 + * Only need to enable discards if the pool should pass
  2007 + * them down to the data device. The thin device's discard
  2008 + * processing will cause mappings to be removed from the btree.
  2009 + */
  2010 + if (pf.discard_enabled && pf.discard_passdown) {
  2011 + ti->num_discard_requests = 1;
  2012 + /*
  2013 + * Setting 'discards_supported' circumvents the normal
  2014 + * stacking of discard limits (this keeps the pool and
  2015 + * thin devices' discard limits consistent).
  2016 + */
  2017 + ti->discards_supported = 1;
  2018 + }
1961 2019 ti->private = pt;
1962 2020  
1963 2021 pt->callbacks.congested_fn = pool_is_congested;
... ... @@ -1967,6 +2025,8 @@
1967 2025  
1968 2026 return 0;
1969 2027  
  2028 +out_flags_changed:
  2029 + __pool_dec(pool);
1970 2030 out_free_pt:
1971 2031 kfree(pt);
1972 2032 out:
... ... @@ -2255,7 +2315,7 @@
2255 2315 static int pool_status(struct dm_target *ti, status_type_t type,
2256 2316 char *result, unsigned maxlen)
2257 2317 {
2258   - int r;
  2318 + int r, count;
2259 2319 unsigned sz = 0;
2260 2320 uint64_t transaction_id;
2261 2321 dm_block_t nr_free_blocks_data;
2262 2322  
2263 2323  
... ... @@ -2318,10 +2378,19 @@
2318 2378 (unsigned long)pool->sectors_per_block,
2319 2379 (unsigned long long)pt->low_water_blocks);
2320 2380  
2321   - DMEMIT("%u ", !pool->zero_new_blocks);
  2381 + count = !pool->pf.zero_new_blocks + !pool->pf.discard_enabled +
  2382 + !pool->pf.discard_passdown;
  2383 + DMEMIT("%u ", count);
2322 2384  
2323   - if (!pool->zero_new_blocks)
  2385 + if (!pool->pf.zero_new_blocks)
2324 2386 DMEMIT("skip_block_zeroing ");
  2387 +
  2388 + if (!pool->pf.discard_enabled)
  2389 + DMEMIT("ignore_discard ");
  2390 +
  2391 + if (!pool->pf.discard_passdown)
  2392 + DMEMIT("no_discard_passdown ");
  2393 +
2325 2394 break;
2326 2395 }
2327 2396  
... ... @@ -2352,6 +2421,9 @@
2352 2421  
2353 2422 static void set_discard_limits(struct pool *pool, struct queue_limits *limits)
2354 2423 {
  2424 + /*
  2425 + * FIXME: these limits may be incompatible with the pool's data device
  2426 + */
2355 2427 limits->max_discard_sectors = pool->sectors_per_block;
2356 2428  
2357 2429 /*
... ... @@ -2359,6 +2431,7 @@
2359 2431 * bios that overlap 2 blocks.
2360 2432 */
2361 2433 limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
  2434 + limits->discard_zeroes_data = pool->pf.zero_new_blocks;
2362 2435 }
2363 2436  
2364 2437 static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
2365 2438  
... ... @@ -2368,14 +2441,15 @@
2368 2441  
2369 2442 blk_limits_io_min(limits, 0);
2370 2443 blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
2371   - set_discard_limits(pool, limits);
  2444 + if (pool->pf.discard_enabled)
  2445 + set_discard_limits(pool, limits);
2372 2446 }
2373 2447  
2374 2448 static struct target_type pool_target = {
2375 2449 .name = "thin-pool",
2376 2450 .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
2377 2451 DM_TARGET_IMMUTABLE,
2378   - .version = {1, 0, 0},
  2452 + .version = {1, 1, 0},
2379 2453 .module = THIS_MODULE,
2380 2454 .ctr = pool_ctr,
2381 2455 .dtr = pool_dtr,
... ... @@ -2417,6 +2491,9 @@
2417 2491 * pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
2418 2492 * dev_id: the internal device identifier
2419 2493 * origin_dev: a device external to the pool that should act as the origin
  2494 + *
  2495 + * If the pool device has discards disabled, they get disabled for the thin
  2496 + * device as well.
2420 2497 */
2421 2498 static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
2422 2499 {
... ... @@ -2485,8 +2562,12 @@
2485 2562  
2486 2563 ti->split_io = tc->pool->sectors_per_block;
2487 2564 ti->num_flush_requests = 1;
2488   - ti->num_discard_requests = 1;
2489   - ti->discards_supported = 1;
  2565 +
  2566 + /* In case the pool supports discards, pass them on. */
  2567 + if (tc->pool->pf.discard_enabled) {
  2568 + ti->discards_supported = 1;
  2569 + ti->num_discard_requests = 1;
  2570 + }
2490 2571  
2491 2572 dm_put(pool_md);
2492 2573