block: discard granularity might not be power of 2
In MD raid case, discard granularity might not be power of 2, for example, a
4-disk raid5 has 3*chunk_size discard granularity. Correct the calculation for
such cases.
Reported-by: Neil Brown <neilb@suse.de>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 9373b58..5677fd3 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -43,8 +43,8 @@
DECLARE_COMPLETION_ONSTACK(wait);
struct request_queue *q = bdev_get_queue(bdev);
int type = REQ_WRITE | REQ_DISCARD;
- unsigned int max_discard_sectors;
- unsigned int granularity, alignment, mask;
+ sector_t max_discard_sectors;
+ sector_t granularity, alignment;
struct bio_batch bb;
struct bio *bio;
int ret = 0;
@@ -57,15 +57,16 @@
/* 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;
+ alignment = bdev_discard_alignment(bdev) >> 9;
+ alignment = sector_div(alignment, granularity);
/*
* Ensure that max_discard_sectors is of the proper
* 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);
+ sector_div(max_discard_sectors, granularity);
+ max_discard_sectors *= granularity;
if (unlikely(!max_discard_sectors)) {
/* Avoid infinite loop below. Being cautious never hurts. */
return -EOPNOTSUPP;
@@ -83,7 +84,7 @@
while (nr_sects) {
unsigned int req_sects;
- sector_t end_sect;
+ sector_t end_sect, tmp;
bio = bio_alloc(gfp_mask, 1);
if (!bio) {
@@ -98,10 +99,12 @@
* 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;
+ 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;
}