From 202bae52934d4eb79ffaebf49f49b1cc64d8e40b Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Wed, 4 May 2016 14:12:42 -0400 Subject: [PATCH] dm thin: unroll issue_discard() to create longer discard bio chains There is little benefit to doing this but it does structure DM thinp's code to more cleanly use the __blkdev_issue_discard() interface -- particularly in passdown_double_checking_shared_status(). Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/dm-thin.c | 108 ++++++++++++++++++++++++++++--------------- 1 file changed, 71 insertions(+), 37 deletions(-) diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 598a78ba894b..fc803d50f9f0 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -334,26 +334,55 @@ static sector_t block_to_sectors(struct pool *pool, dm_block_t b) (b * pool->sectors_per_block); } -static int issue_discard(struct thin_c *tc, dm_block_t data_b, dm_block_t data_e, - struct bio *parent_bio) +/*----------------------------------------------------------------*/ + +struct discard_op { + struct thin_c *tc; + struct blk_plug plug; + struct bio *parent_bio; + struct bio *bio; +}; + +static void begin_discard(struct discard_op *op, struct thin_c *tc, struct bio *parent) { - int type = REQ_WRITE | REQ_DISCARD; + BUG_ON(!parent); + + op->tc = tc; + blk_start_plug(&op->plug); + op->parent_bio = parent; + op->bio = NULL; +} + +static int issue_discard(struct discard_op *op, dm_block_t data_b, dm_block_t data_e) +{ + struct thin_c *tc = op->tc; sector_t s = block_to_sectors(tc->pool, data_b); sector_t len = block_to_sectors(tc->pool, data_e - data_b); - struct bio *bio = NULL; - struct blk_plug plug; - int ret; - blk_start_plug(&plug); - ret = __blkdev_issue_discard(tc->pool_dev->bdev, s, len, - GFP_NOWAIT, type, &bio); - if (!ret && bio) { - bio_chain(bio, parent_bio); - submit_bio(type, bio); + return __blkdev_issue_discard(tc->pool_dev->bdev, s, len, + GFP_NOWAIT, REQ_WRITE | REQ_DISCARD, &op->bio); +} + +static void end_discard(struct discard_op *op, int r) +{ + if (op->bio) { + /* + * Even if one of the calls to issue_discard failed, we + * need to wait for the chain to complete. + */ + bio_chain(op->bio, op->parent_bio); + submit_bio(REQ_WRITE | REQ_DISCARD, op->bio); } - blk_finish_plug(&plug); - return ret; + blk_finish_plug(&op->plug); + + /* + * Even if r is set, there could be sub discards in flight that we + * need to wait for. + */ + if (r && !op->parent_bio->bi_error) + op->parent_bio->bi_error = r; + bio_endio(op->parent_bio); } /*----------------------------------------------------------------*/ @@ -968,24 +997,28 @@ static void process_prepared_discard_no_passdown(struct dm_thin_new_mapping *m) mempool_free(m, tc->pool->mapping_pool); } -static int passdown_double_checking_shared_status(struct dm_thin_new_mapping *m) +/*----------------------------------------------------------------*/ + +static void passdown_double_checking_shared_status(struct dm_thin_new_mapping *m) { /* * We've already unmapped this range of blocks, but before we * passdown we have to check that these blocks are now unused. */ - int r; + int r = 0; bool used = true; struct thin_c *tc = m->tc; struct pool *pool = tc->pool; dm_block_t b = m->data_block, e, end = m->data_block + m->virt_end - m->virt_begin; + struct discard_op op; + begin_discard(&op, tc, m->bio); while (b != end) { /* find start of unmapped run */ for (; b < end; b++) { r = dm_pool_block_is_used(pool->pmd, b, &used); if (r) - return r; + goto out; if (!used) break; @@ -998,20 +1031,20 @@ static int passdown_double_checking_shared_status(struct dm_thin_new_mapping *m) for (e = b + 1; e != end; e++) { r = dm_pool_block_is_used(pool->pmd, e, &used); if (r) - return r; + goto out; if (used) break; } - r = issue_discard(tc, b, e, m->bio); + r = issue_discard(&op, b, e); if (r) - return r; + goto out; b = e; } - - return 0; +out: + end_discard(&op, r); } static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m) @@ -1021,20 +1054,21 @@ static void process_prepared_discard_passdown(struct dm_thin_new_mapping *m) struct pool *pool = tc->pool; r = dm_thin_remove_range(tc->td, m->virt_begin, m->virt_end); - if (r) + if (r) { metadata_operation_failed(pool, "dm_thin_remove_range", r); + bio_io_error(m->bio); - else if (m->maybe_shared) - r = passdown_double_checking_shared_status(m); - else - r = issue_discard(tc, m->data_block, m->data_block + (m->virt_end - m->virt_begin), m->bio); + } else if (m->maybe_shared) { + passdown_double_checking_shared_status(m); + + } else { + struct discard_op op; + begin_discard(&op, tc, m->bio); + r = issue_discard(&op, m->data_block, + m->data_block + (m->virt_end - m->virt_begin)); + end_discard(&op, r); + } - /* - * Even if r is set, there could be sub discards in flight that we - * need to wait for. - */ - m->bio->bi_error = r; - bio_endio(m->bio); cell_defer_no_holder(tc, m->cell); mempool_free(m, pool->mapping_pool); } @@ -1505,11 +1539,11 @@ static void break_up_discard_bio(struct thin_c *tc, dm_block_t begin, dm_block_t /* * The parent bio must not complete before sub discard bios are - * chained to it (see issue_discard's bio_chain)! + * chained to it (see end_discard's bio_chain)! * * This per-mapping bi_remaining increment is paired with * the implicit decrement that occurs via bio_endio() in - * process_prepared_discard_passdown(). + * end_discard(). */ bio_inc_remaining(bio); if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) @@ -3850,7 +3884,7 @@ static struct target_type pool_target = { .name = "thin-pool", .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE | DM_TARGET_IMMUTABLE, - .version = {1, 18, 0}, + .version = {1, 19, 0}, .module = THIS_MODULE, .ctr = pool_ctr, .dtr = pool_dtr, @@ -4224,7 +4258,7 @@ static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits) static struct target_type thin_target = { .name = "thin", - .version = {1, 18, 0}, + .version = {1, 19, 0}, .module = THIS_MODULE, .ctr = thin_ctr, .dtr = thin_dtr,