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| author | Martin K. Petersen <martin.petersen@oracle.com> | 2009-05-22 17:17:53 -0400 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-05-22 23:22:55 +0200 |
| commit | c72758f33784e5e2a1a4bb9421ef3e6de8f9fcf3 (patch) | |
| tree | a83f7540cc894caafe74db911cba3998d6a9a164 /block/genhd.c | |
| parent | cd43e26f071524647e660706b784ebcbefbd2e44 (diff) | |
| download | lwn-c72758f33784e5e2a1a4bb9421ef3e6de8f9fcf3.tar.gz lwn-c72758f33784e5e2a1a4bb9421ef3e6de8f9fcf3.zip | |
block: Export I/O topology for block devices and partitions
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>
Diffstat (limited to 'block/genhd.c')
| -rw-r--r-- | block/genhd.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/block/genhd.c b/block/genhd.c index 1a4916e01732..fe7ccc0a618f 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -852,11 +852,21 @@ static ssize_t disk_capability_show(struct device *dev, return sprintf(buf, "%x\n", disk->flags); } +static ssize_t disk_alignment_offset_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct gendisk *disk = dev_to_disk(dev); + + return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue)); +} + static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL); static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL); static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL); static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL); static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL); +static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL); static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL); static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL); #ifdef CONFIG_FAIL_MAKE_REQUEST @@ -875,6 +885,7 @@ static struct attribute *disk_attrs[] = { &dev_attr_removable.attr, &dev_attr_ro.attr, &dev_attr_size.attr, + &dev_attr_alignment_offset.attr, &dev_attr_capability.attr, &dev_attr_stat.attr, #ifdef CONFIG_FAIL_MAKE_REQUEST |