diff options
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r-- | block/blk-settings.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 94410a13c0de..fd83d674afd0 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -478,6 +478,30 @@ static int queue_limit_alignment_offset(struct queue_limits *lim, return (granularity + lim->alignment_offset - alignment) % granularity; } +static unsigned int queue_limit_discard_alignment(struct queue_limits *lim, + sector_t sector) +{ + unsigned int alignment, granularity, offset; + + if (!lim->max_discard_sectors) + return 0; + + /* Why are these in bytes, not sectors? */ + alignment = lim->discard_alignment >> SECTOR_SHIFT; + granularity = lim->discard_granularity >> SECTOR_SHIFT; + 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 << SECTOR_SHIFT; +} + static unsigned int blk_round_down_sectors(unsigned int sectors, unsigned int lbs) { sectors = round_down(sectors, lbs >> SECTOR_SHIFT); @@ -924,3 +948,14 @@ int bdev_alignment_offset(struct block_device *bdev) return q->limits.alignment_offset; } EXPORT_SYMBOL_GPL(bdev_alignment_offset); + +unsigned int bdev_discard_alignment(struct block_device *bdev) +{ + struct request_queue *q = bdev_get_queue(bdev); + + if (bdev_is_partition(bdev)) + return queue_limit_discard_alignment(&q->limits, + bdev->bd_start_sect); + return q->limits.discard_alignment; +} +EXPORT_SYMBOL_GPL(bdev_discard_alignment); |