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-rw-r--r--block/blk-lib.c41
1 files changed, 28 insertions, 13 deletions
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 2b461b4..19cc761 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -44,6 +44,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
struct request_queue *q = bdev_get_queue(bdev);
int type = REQ_WRITE | REQ_DISCARD;
unsigned int max_discard_sectors;
+ unsigned int granularity, alignment, mask;
struct bio_batch bb;
struct bio *bio;
int ret = 0;
@@ -54,18 +55,20 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
if (!blk_queue_discard(q))
return -EOPNOTSUPP;
+ /* Zero-sector (unknown) and one-sector granularities are the same. */
+ granularity = max(q->limits.discard_granularity >> 9, 1U);
+ mask = granularity - 1;
+ alignment = (bdev_discard_alignment(bdev) >> 9) & mask;
+
/*
* Ensure that max_discard_sectors is of the proper
- * granularity
+ * granularity, so that requests stay aligned after a split.
*/
max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+ max_discard_sectors = round_down(max_discard_sectors, granularity);
if (unlikely(!max_discard_sectors)) {
/* Avoid infinite loop below. Being cautious never hurts. */
return -EOPNOTSUPP;
- } else if (q->limits.discard_granularity) {
- unsigned int disc_sects = q->limits.discard_granularity >> 9;
-
- max_discard_sectors &= ~(disc_sects - 1);
}
if (flags & BLKDEV_DISCARD_SECURE) {
@@ -79,25 +82,37 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
bb.wait = &wait;
while (nr_sects) {
+ unsigned int req_sects;
+ sector_t end_sect;
+
bio = bio_alloc(gfp_mask, 1);
if (!bio) {
ret = -ENOMEM;
break;
}
+ req_sects = min_t(sector_t, nr_sects, max_discard_sectors);
+
+ /*
+ * If splitting a request, and the next starting sector would be
+ * misaligned, stop the discard at the previous aligned sector.
+ */
+ end_sect = sector + req_sects;
+ if (req_sects < nr_sects && (end_sect & mask) != alignment) {
+ end_sect =
+ round_down(end_sect - alignment, granularity)
+ + alignment;
+ req_sects = end_sect - sector;
+ }
+
bio->bi_sector = sector;
bio->bi_end_io = bio_batch_end_io;
bio->bi_bdev = bdev;
bio->bi_private = &bb;
- if (nr_sects > max_discard_sectors) {
- bio->bi_size = max_discard_sectors << 9;
- nr_sects -= max_discard_sectors;
- sector += max_discard_sectors;
- } else {
- bio->bi_size = nr_sects << 9;
- nr_sects = 0;
- }
+ bio->bi_size = req_sects << 9;
+ nr_sects -= req_sects;
+ sector = end_sect;
atomic_inc(&bb.done);
submit_bio(type, bio);