Commit 744889b7 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: don't deal with discard limit in blkdev_issue_discard()

blk_queue_split() does respect this limit via bio splitting, so no
need to do that in blkdev_issue_discard(), then we can align to
normal bio submit(bio_add_page() & submit_bio()).

More importantly, this patch fixes one issue introduced in a22c4d7e
("block: re-add discard_granularity and alignment checks"), in which
zero discard bio may be generated in case of zero alignment.

Fixes: a22c4d7e

 ("block: re-add discard_granularity and alignment checks")
Cc: Ming Lin <>
Cc: Mike Snitzer <>
Cc: Christoph Hellwig <>
Cc: Xiao Ni <>
Tested-by: default avatarMariusz Dabrowski <>
Signed-off-by: default avatarMing Lei <>
Signed-off-by: default avatarJens Axboe <>
parent 7a7080b5
......@@ -29,9 +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 granularity;
unsigned int op;
int alignment;
sector_t bs_mask;
if (!q)
......@@ -54,38 +52,16 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
if ((sector | nr_sects) & bs_mask)
return -EINVAL;
/* Zero-sector (unknown) and one-sector granularities are the same. */
granularity = max(q->limits.discard_granularity >> 9, 1U);
alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
while (nr_sects) {
unsigned int req_sects;
sector_t end_sect, tmp;
unsigned int req_sects = nr_sects;
sector_t end_sect;
* Issue in chunks of the user defined max discard setting,
* ensuring that bi_size doesn't overflow
req_sects = min_t(sector_t, nr_sects,
if (!req_sects)
goto fail;
if (req_sects > UINT_MAX >> 9)
req_sects = UINT_MAX >> 9;
* 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;
tmp = end_sect;
if (req_sects < nr_sects &&
sector_div(tmp, granularity) != alignment) {
end_sect = end_sect - alignment;
sector_div(end_sect, granularity);
end_sect = end_sect * granularity + alignment;
req_sects = end_sect - sector;
bio = next_bio(bio, 0, gfp_mask);
bio->bi_iter.bi_sector = sector;
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