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>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b7bb6fd..5e740a1 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -314,11 +314,16 @@
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_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 @@
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;