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block: Expose discard granularity

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While SSDs track block usage on a per-sector basis, RAID arrays often
have allocation blocks that are bigger.  Allow the discard granularity
and alignment to be set and teach the topology stacking logic how to
handle them.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Martin K. Petersen
2009-11-10 11:50:21 +01:00
committed by Jens Axboe
parent cf7c25cf91
commit 86b3728141
6 changed files with 101 additions and 10 deletions
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18
include/linux/blkdev.h
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@@ -312,12 +312,15 @@ struct queue_limits {
unsigned int io_min;
unsigned int io_opt;
unsigned int max_discard_sectors;
unsigned int discard_granularity;
unsigned int discard_alignment;
unsigned short logical_block_size;
unsigned short max_hw_segments;
unsigned short max_phys_segments;
unsigned char misaligned;
unsigned char discard_misaligned;
unsigned char no_cluster;
};
@@ -1121,6 +1124,21 @@ static inline int bdev_alignment_offset(struct block_device *bdev)
return q->limits.alignment_offset;
}
static inline int queue_discard_alignment(struct request_queue *q)
{
if (q->limits.discard_misaligned)
return -1;
return q->limits.discard_alignment;
}
static inline int queue_sector_discard_alignment(struct request_queue *q,
sector_t sector)
{
return ((sector << 9) - q->limits.discard_alignment)
& (q->limits.discard_granularity - 1);
}
static inline int queue_dma_alignment(struct request_queue *q)
{
return q ? q->dma_alignment : 511;