Merge branch 'for-5.9/block' into for-5.9/block-merge

* for-5.9/block: (124 commits)
  blk-cgroup: show global disk stats in root cgroup io.stat
  blk-cgroup: make iostat functions visible to stat printing
  block: improve discard bio alignment in __blkdev_issue_discard()
  block: change REQ_OP_ZONE_RESET and REQ_OP_ZONE_RESET_ALL to be odd numbers
  block: defer flush request no matter whether we have elevator
  block: make blk_timeout_init() static
  block: remove retry loop in ioc_release_fn()
  block: remove unnecessary ioc nested locking
  block: integrate bd_start_claiming into __blkdev_get
  block: use bd_prepare_to_claim directly in the loop driver
  block: refactor bd_start_claiming
  block: simplify the restart case in __blkdev_get
  Revert "blk-rq-qos: remove redundant finish_wait to rq_qos_wait."
  block: always remove partitions from blk_drop_partitions()
  block: relax jiffies rounding for timeouts
  blk-mq: remove redundant validation in __blk_mq_end_request()
  blk-mq: Remove unnecessary local variable
  writeback: remove bdi->congested_fn
  writeback: remove struct bdi_writeback_congested
  writeback: remove {set,clear}_wb_congested
  ...

1 files changed, 28 insertions, 3 deletions

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 5f2c429d4378..019e09bb9c0e 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -29,7 +29,7 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 	struct request_queue *q = bdev_get_queue(bdev);
 	struct bio *bio = *biop;
 	unsigned int op;
-	sector_t bs_mask;
+	sector_t bs_mask, part_offset = 0;
 
 	if (!q)
 		return -ENXIO;
@@ -54,9 +54,34 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 	if (!nr_sects)
 		return -EINVAL;
 
+	/* In case the discard request is in a partition */
+	if (bdev->bd_partno)
+		part_offset = bdev->bd_part->start_sect;
+
 	while (nr_sects) {
-		sector_t req_sects = min_t(sector_t, nr_sects,
-				bio_allowed_max_sectors(q));
+		sector_t granularity_aligned_lba, req_sects;
+		sector_t sector_mapped = sector + part_offset;
+
+		granularity_aligned_lba = round_up(sector_mapped,
+				q->limits.discard_granularity >> SECTOR_SHIFT);
+
+		/*
+		 * Check whether the discard bio starts at a discard_granularity
+		 * aligned LBA,
+		 * - If no: set (granularity_aligned_lba - sector_mapped) to
+		 *   bi_size of the first split bio, then the second bio will
+		 *   start at a discard_granularity aligned LBA on the device.
+		 * - If yes: use bio_aligned_discard_max_sectors() as the max
+		 *   possible bi_size of the first split bio. Then when this bio
+		 *   is split in device drive, the split ones are very probably
+		 *   to be aligned to discard_granularity of the device's queue.
+		 */
+		if (granularity_aligned_lba == sector_mapped)
+			req_sects = min_t(sector_t, nr_sects,
+					  bio_aligned_discard_max_sectors(q));
+		else
+			req_sects = min_t(sector_t, nr_sects,
+					  granularity_aligned_lba - sector_mapped);
 
 		WARN_ON_ONCE((req_sects << 9) > UINT_MAX);