From 57cba5d3658d9fdc019c6af14a2d80aefa651e56 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 12 Aug 2010 04:14:04 +0100 Subject: dm: rename map_info flush_request to target_request_nr 'target_request_nr' is a more generic name that reflects the fact that it will be used for both flush and discard support. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- include/linux/device-mapper.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/device-mapper.h') diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 1381cd97b4ed..531a6f2635ae 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -22,7 +22,7 @@ typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t; union map_info { void *ptr; unsigned long long ll; - unsigned flush_request; + unsigned target_request_nr; }; /* @@ -174,7 +174,7 @@ struct dm_target { * A number of zero-length barrier requests that will be submitted * to the target for the purpose of flushing cache. * - * The request number will be placed in union map_info->flush_request. + * The request number will be placed in union map_info->target_request_nr. * It is a responsibility of the target driver to remap these requests * to the real underlying devices. */ -- cgit v1.2.3 From 5ae89a8720c28caf35c4e53711d77df2856c404e Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 12 Aug 2010 04:14:08 +0100 Subject: dm: linear support discard Allow discards to be passed through to linear mappings if at least one underlying device supports it. Discards will be forwarded only to devices that support them. A target that supports discards should set num_discard_requests to indicate how many times each discard request must be submitted to it. Verify table's underlying devices support discards prior to setting the associated DM device as capable of discards (via QUEUE_FLAG_DISCARD). Signed-off-by: Mike Snitzer Signed-off-by: Mikulas Patocka Reviewed-by: Joe Thornber Signed-off-by: Alasdair G Kergon --- drivers/md/dm-linear.c | 1 + drivers/md/dm-table.c | 44 +++++++++++++++++++++++++++++ drivers/md/dm.c | 65 +++++++++++++++++++++++++++++++++++-------- drivers/md/dm.h | 1 + include/linux/device-mapper.h | 6 ++++ 5 files changed, 105 insertions(+), 12 deletions(-) (limited to 'include/linux/device-mapper.h') diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c index 9200dbf2391a..f043b5f433b2 100644 --- a/drivers/md/dm-linear.c +++ b/drivers/md/dm-linear.c @@ -53,6 +53,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv) } ti->num_flush_requests = 1; + ti->num_discard_requests = 1; ti->private = lc; return 0; diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index bc60ef77a0d8..f9fc07d7a4b9 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -54,6 +54,8 @@ struct dm_table { sector_t *highs; struct dm_target *targets; + unsigned discards_supported:1; + /* * Indicates the rw permissions for the new logical * device. This should be a combination of FMODE_READ @@ -203,6 +205,7 @@ int dm_table_create(struct dm_table **result, fmode_t mode, INIT_LIST_HEAD(&t->devices); atomic_set(&t->holders, 0); + t->discards_supported = 1; if (!num_targets) num_targets = KEYS_PER_NODE; @@ -770,6 +773,9 @@ int dm_table_add_target(struct dm_table *t, const char *type, t->highs[t->num_targets++] = tgt->begin + tgt->len - 1; + if (!tgt->num_discard_requests) + t->discards_supported = 0; + return 0; bad: @@ -1135,6 +1141,11 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, else queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, q); + if (!dm_table_supports_discards(t)) + queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); + else + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); + dm_table_set_integrity(t); /* @@ -1281,6 +1292,39 @@ struct mapped_device *dm_table_get_md(struct dm_table *t) return t->md; } +static int device_discard_capable(struct dm_target *ti, struct dm_dev *dev, + sector_t start, sector_t len, void *data) +{ + struct request_queue *q = bdev_get_queue(dev->bdev); + + return q && blk_queue_discard(q); +} + +bool dm_table_supports_discards(struct dm_table *t) +{ + struct dm_target *ti; + unsigned i = 0; + + if (!t->discards_supported) + return 0; + + /* + * Ensure that at least one underlying device supports discards. + * t->devices includes internal dm devices such as mirror logs + * so we need to use iterate_devices here, which targets + * supporting discard must provide. + */ + while (i < dm_table_get_num_targets(t)) { + ti = dm_table_get_target(t, i++); + + if (ti->type->iterate_devices && + ti->type->iterate_devices(ti, device_discard_capable, NULL)) + return 1; + } + + return 0; +} + EXPORT_SYMBOL(dm_vcalloc); EXPORT_SYMBOL(dm_get_device); EXPORT_SYMBOL(dm_put_device); diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 0d4710175885..44aba29154fc 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1212,6 +1212,53 @@ static int __clone_and_map_empty_barrier(struct clone_info *ci) return 0; } +/* + * Perform all io with a single clone. + */ +static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti) +{ + struct bio *clone, *bio = ci->bio; + struct dm_target_io *tio; + + tio = alloc_tio(ci, ti); + clone = clone_bio(bio, ci->sector, ci->idx, + bio->bi_vcnt - ci->idx, ci->sector_count, + ci->md->bs); + __map_bio(ti, clone, tio); + ci->sector_count = 0; +} + +static int __clone_and_map_discard(struct clone_info *ci) +{ + struct dm_target *ti; + sector_t max; + + ti = dm_table_find_target(ci->map, ci->sector); + if (!dm_target_is_valid(ti)) + return -EIO; + + /* + * Even though the device advertised discard support, + * reconfiguration might have changed that since the + * check was performed. + */ + + if (!ti->num_discard_requests) + return -EOPNOTSUPP; + + max = max_io_len(ci->md, ci->sector, ti); + + if (ci->sector_count > max) + /* + * FIXME: Handle a discard that spans two or more targets. + */ + return -EOPNOTSUPP; + + __clone_and_map_simple(ci, ti); + + return 0; +} + static int __clone_and_map(struct clone_info *ci) { struct bio *clone, *bio = ci->bio; @@ -1222,27 +1269,21 @@ static int __clone_and_map(struct clone_info *ci) if (unlikely(bio_empty_barrier(bio))) return __clone_and_map_empty_barrier(ci); + if (unlikely(bio->bi_rw & REQ_DISCARD)) + return __clone_and_map_discard(ci); + ti = dm_table_find_target(ci->map, ci->sector); if (!dm_target_is_valid(ti)) return -EIO; max = max_io_len(ci->md, ci->sector, ti); - /* - * Allocate a target io object. - */ - tio = alloc_tio(ci, ti); - if (ci->sector_count <= max) { /* * Optimise for the simple case where we can do all of * the remaining io with a single clone. */ - clone = clone_bio(bio, ci->sector, ci->idx, - bio->bi_vcnt - ci->idx, ci->sector_count, - ci->md->bs); - __map_bio(ti, clone, tio); - ci->sector_count = 0; + __clone_and_map_simple(ci, ti); } else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) { /* @@ -1263,6 +1304,7 @@ static int __clone_and_map(struct clone_info *ci) len += bv_len; } + tio = alloc_tio(ci, ti); clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len, ci->md->bs); __map_bio(ti, clone, tio); @@ -1286,12 +1328,11 @@ static int __clone_and_map(struct clone_info *ci) return -EIO; max = max_io_len(ci->md, ci->sector, ti); - - tio = alloc_tio(ci, ti); } len = min(remaining, max); + tio = alloc_tio(ci, ti); clone = split_bvec(bio, ci->sector, ci->idx, bv->bv_offset + offset, len, ci->md->bs); diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 0d7b374c5dc2..0c2dd5f4af76 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -61,6 +61,7 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits); int dm_table_any_busy_target(struct dm_table *t); unsigned dm_table_get_type(struct dm_table *t); bool dm_table_request_based(struct dm_table *t); +bool dm_table_supports_discards(struct dm_table *t); int dm_table_alloc_md_mempools(struct dm_table *t); void dm_table_free_md_mempools(struct dm_table *t); struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t); diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 531a6f2635ae..751ce21dea7b 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -180,6 +180,12 @@ struct dm_target { */ unsigned num_flush_requests; + /* + * The number of discard requests that will be submitted to the + * target. map_info->request_nr is used just like num_flush_requests. + */ + unsigned num_discard_requests; + /* target specific data */ void *private; -- cgit v1.2.3 From 56a67df766039666f61fb15b079f713e44a735ae Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 12 Aug 2010 04:14:10 +0100 Subject: dm: factor out max_io_len_target_boundary Split max_io_len_target_boundary out of max_io_len so that the discard support can make use of it without duplicating max_io_len code. Avoiding max_io_len's split_io logic enables DM's discard support to submit the entire discard request to a target. But discards must still be split on target boundaries. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm.c | 26 ++++++++++++++++++-------- include/linux/device-mapper.h | 6 ++++++ 2 files changed, 24 insertions(+), 8 deletions(-) (limited to 'include/linux/device-mapper.h') diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 3dd846e801fb..561313a7dac2 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1030,17 +1030,27 @@ static void end_clone_request(struct request *clone, int error) dm_complete_request(clone, error); } -static sector_t max_io_len(struct mapped_device *md, - sector_t sector, struct dm_target *ti) +/* + * Return maximum size of I/O possible at the supplied sector up to the current + * target boundary. + */ +static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti) +{ + sector_t target_offset = dm_target_offset(ti, sector); + + return ti->len - target_offset; +} + +static sector_t max_io_len(sector_t sector, struct dm_target *ti) { - sector_t offset = sector - ti->begin; - sector_t len = ti->len - offset; + sector_t len = max_io_len_target_boundary(sector, ti); /* * Does the target need to split even further ? */ if (ti->split_io) { sector_t boundary; + sector_t offset = dm_target_offset(ti, sector); boundary = ((offset + ti->split_io) & ~(ti->split_io - 1)) - offset; if (len > boundary) @@ -1258,7 +1268,7 @@ static int __clone_and_map_discard(struct clone_info *ci) if (!ti->num_discard_requests) return -EOPNOTSUPP; - max = max_io_len(ci->md, ci->sector, ti); + max = max_io_len(ci->sector, ti); if (ci->sector_count > max) /* @@ -1290,7 +1300,7 @@ static int __clone_and_map(struct clone_info *ci) if (!dm_target_is_valid(ti)) return -EIO; - max = max_io_len(ci->md, ci->sector, ti); + max = max_io_len(ci->sector, ti); if (ci->sector_count <= max) { /* @@ -1341,7 +1351,7 @@ static int __clone_and_map(struct clone_info *ci) if (!dm_target_is_valid(ti)) return -EIO; - max = max_io_len(ci->md, ci->sector, ti); + max = max_io_len(ci->sector, ti); } len = min(remaining, max); @@ -1428,7 +1438,7 @@ static int dm_merge_bvec(struct request_queue *q, /* * Find maximum amount of I/O that won't need splitting */ - max_sectors = min(max_io_len(md, bvm->bi_sector, ti), + max_sectors = min(max_io_len(bvm->bi_sector, ti), (sector_t) BIO_MAX_SECTORS); max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size; if (max_size < 0) diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 751ce21dea7b..2970022faa63 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -398,6 +398,12 @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size); #define dm_array_too_big(fixed, obj, num) \ ((num) > (UINT_MAX - (fixed)) / (obj)) +/* + * Sector offset taken relative to the start of the target instead of + * relative to the start of the device. + */ +#define dm_target_offset(ti, sector) ((sector) - (ti)->begin) + static inline sector_t to_sector(unsigned long n) { return (n >> SECTOR_SHIFT); -- cgit v1.2.3