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authorBart Van Assche <bvanassche@acm.org>2019-06-28 13:07:45 -0700
committerJens Axboe <axboe@kernel.dk>2019-06-29 09:38:05 -0600
commitfbbe7c86b483878da4a2ec7b899e0814195942af (patch)
treec40d8d4a78836241d5df973396e3ad952909d22b
parent0c766e78bda6d4edf40779fc0cd48d0867a04d84 (diff)
block, documentation: Document discard_zeroes_data, fua, max_discard_segments and write_zeroes_max_bytes
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--Documentation/block/queue-sysfs.txt20
1 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index 1515dcf3dec4..b40b5b7cebd9 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -52,6 +52,16 @@ large discards are issued, setting this value lower will make Linux issue
smaller discards and potentially help reduce latencies induced by large
discard operations.
+discard_zeroes_data (RO)
+------------------------
+Obsolete. Always zero.
+
+fua (RO)
+--------
+Whether or not the block driver supports the FUA flag for write requests.
+FUA stands for Force Unit Access. If the FUA flag is set that means that
+write requests must bypass the volatile cache of the storage device.
+
hw_sector_size (RO)
-------------------
This is the hardware sector size of the device, in bytes.
@@ -92,6 +102,10 @@ logical_block_size (RO)
-----------------------
This is the logical block size of the device, in bytes.
+max_discard_segments (RO)
+-------------------------
+The maximum number of DMA scatter/gather entries in a discard request.
+
max_hw_sectors_kb (RO)
----------------------
This is the maximum number of kilobytes supported in a single data transfer.
@@ -218,6 +232,12 @@ blk-throttle makes decision based on the samplings. Lower time means cgroups
have more smooth throughput, but higher CPU overhead. This exists only when
CONFIG_BLK_DEV_THROTTLING_LOW is enabled.
+write_zeroes_max_bytes (RO)
+---------------------------
+For block drivers that support REQ_OP_WRITE_ZEROES, the maximum number of
+bytes that can be zeroed at once. The value 0 means that REQ_OP_WRITE_ZEROES
+is not supported.
+
zoned (RO)
----------
This indicates if the device is a zoned block device and the zone model of the