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block: Export I/O topology for block devices and partitions

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To support devices with physical block sizes bigger than 512 bytes we
need to ensure proper alignment.  This patch adds support for exposing
I/O topology characteristics as devices are stacked.

  logical_block_size is the smallest unit the device can address.

  physical_block_size indicates the smallest I/O the device can write
  without incurring a read-modify-write penalty.

  The io_min parameter is the smallest preferred I/O size reported by
  the device.  In many cases this is the same as the physical block
  size.  However, the io_min parameter can be scaled up when stacking
  (RAID5 chunk size > physical block size).

  The io_opt characteristic indicates the optimal I/O size reported by
  the device.  This is usually the stripe width for arrays.

  The alignment_offset parameter indicates the number of bytes the start
  of the device/partition is offset from the device's natural alignment.
  Partition tools and MD/DM utilities can use this to pad their offsets
  so filesystems start on proper boundaries.

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
2009-05-22 17:17:53 -04:00
committed by Jens Axboe
parent cd43e26f07
commit c72758f337
7 changed files with 347 additions and 0 deletions
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47
include/linux/blkdev.h
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@@ -314,11 +314,16 @@ struct queue_limits {
unsigned int max_hw_sectors;
unsigned int max_sectors;
unsigned int max_segment_size;
unsigned int physical_block_size;
unsigned int alignment_offset;
unsigned int io_min;
unsigned int io_opt;
unsigned short logical_block_size;
unsigned short max_hw_segments;
unsigned short max_phys_segments;
unsigned char misaligned;
unsigned char no_cluster;
};
@@ -911,6 +916,15 @@ extern void blk_queue_max_phys_segments(struct request_queue *, unsigned short);
extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short);
extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
extern void blk_queue_logical_block_size(struct request_queue *, unsigned short);
extern void blk_queue_physical_block_size(struct request_queue *, unsigned short);
extern void blk_queue_alignment_offset(struct request_queue *q,
unsigned int alignment);
extern void blk_queue_io_min(struct request_queue *q, unsigned int min);
extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt);
extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
sector_t offset);
extern void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
sector_t offset);
extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b);
extern void blk_queue_dma_pad(struct request_queue *, unsigned int);
extern void blk_queue_update_dma_pad(struct request_queue *, unsigned int);
@@ -1047,6 +1061,39 @@ static inline unsigned short bdev_logical_block_size(struct block_device *bdev)
return queue_logical_block_size(bdev_get_queue(bdev));
}
static inline unsigned int queue_physical_block_size(struct request_queue *q)
{
return q->limits.physical_block_size;
}
static inline unsigned int queue_io_min(struct request_queue *q)
{
return q->limits.io_min;
}
static inline unsigned int queue_io_opt(struct request_queue *q)
{
return q->limits.io_opt;
}
static inline int queue_alignment_offset(struct request_queue *q)
{
if (q && q->limits.misaligned)
return -1;
if (q && q->limits.alignment_offset)
return q->limits.alignment_offset;
return 0;
}
static inline int queue_sector_alignment_offset(struct request_queue *q,
sector_t sector)
{
return ((sector << 9) - q->limits.alignment_offset)
& (q->limits.io_min - 1);
}
static inline int queue_dma_alignment(struct request_queue *q)
{
return q ? q->dma_alignment : 511;