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| author | Martin K. Petersen <martin.petersen@oracle.com> | 2012-09-18 12:19:27 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-09-20 14:31:45 +0200 |
| commit | 4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4 (patch) | |
| tree | 010b05699eb9544b9cdfe5e1b3affdaea80132e7 /block/blk-sysfs.c | |
| parent | f31dc1cd490539e2b62a126bc4dc2495b165d772 (diff) | |
| download | linux-4363ac7c13a9a4b763c6e8d9fdbfc2468f3b8ca4.tar.bz2 | |
block: Implement support for WRITE SAME
The WRITE SAME command supported on some SCSI devices allows the same
block to be efficiently replicated throughout a block range. Only a
single logical block is transferred from the host and the storage device
writes the same data to all blocks described by the I/O.
This patch implements support for WRITE SAME in the block layer. The
blkdev_issue_write_same() function can be used by filesystems and block
drivers to replicate a buffer across a block range. This can be used to
efficiently initialize software RAID devices, etc.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-sysfs.c')
| -rw-r--r-- | block/blk-sysfs.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index ea51d827a0bb..247dbfd42621 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -180,6 +180,13 @@ static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *pag return queue_var_show(queue_discard_zeroes_data(q), page); } +static ssize_t queue_write_same_max_show(struct request_queue *q, char *page) +{ + return sprintf(page, "%llu\n", + (unsigned long long)q->limits.max_write_same_sectors << 9); +} + + static ssize_t queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) { @@ -385,6 +392,11 @@ static struct queue_sysfs_entry queue_discard_zeroes_data_entry = { .show = queue_discard_zeroes_data_show, }; +static struct queue_sysfs_entry queue_write_same_max_entry = { + .attr = {.name = "write_same_max_bytes", .mode = S_IRUGO }, + .show = queue_write_same_max_show, +}; + static struct queue_sysfs_entry queue_nonrot_entry = { .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR }, .show = queue_show_nonrot, @@ -432,6 +444,7 @@ static struct attribute *default_attrs[] = { &queue_discard_granularity_entry.attr, &queue_discard_max_entry.attr, &queue_discard_zeroes_data_entry.attr, + &queue_write_same_max_entry.attr, &queue_nonrot_entry.attr, &queue_nomerges_entry.attr, &queue_rq_affinity_entry.attr, |