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-rw-r--r--block/blk-lib.c31
-rw-r--r--block/blk.h14
2 files changed, 42 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);
diff --git a/block/blk.h b/block/blk.h
index 9dcf51c94096..49e2928a1632 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -265,6 +265,20 @@ static inline unsigned int bio_allowed_max_sectors(struct request_queue *q)
}
/*
+ * The max bio size which is aligned to q->limits.discard_granularity. This
+ * is a hint to split large discard bio in generic block layer, then if device
+ * driver needs to split the discard bio into smaller ones, their bi_size can
+ * be very probably and easily aligned to discard_granularity of the device's
+ * queue.
+ */
+static inline unsigned int bio_aligned_discard_max_sectors(
+ struct request_queue *q)
+{
+ return round_down(UINT_MAX, q->limits.discard_granularity) >>
+ SECTOR_SHIFT;
+}
+
+/*
* Internal io_context interface
*/
void get_io_context(struct io_context *ioc);