diff options
| -rw-r--r-- | include/linux/blkdev.h | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index acb4f7bbbd3..f94bc83011e 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1188,14 +1188,25 @@ static inline int queue_discard_alignment(struct request_queue *q) static inline int queue_limit_discard_alignment(struct queue_limits *lim, sector_t sector) { - sector_t alignment = sector << 9; - alignment = sector_div(alignment, lim->discard_granularity); + unsigned int alignment, granularity, offset; if (!lim->max_discard_sectors) return 0; - alignment = lim->discard_granularity + lim->discard_alignment - alignment; - return sector_div(alignment, lim->discard_granularity); + /* Why are these in bytes, not sectors? */ + alignment = lim->discard_alignment >> 9; + granularity = lim->discard_granularity >> 9; + if (!granularity) + return 0; + + /* Offset of the partition start in 'granularity' sectors */ + offset = sector_div(sector, granularity); + + /* And why do we do this modulus *again* in blkdev_issue_discard()? */ + offset = (granularity + alignment - offset) % granularity; + + /* Turn it back into bytes, gaah */ + return offset << 9; } static inline int bdev_discard_alignment(struct block_device *bdev) |