On 09/11/2023 15:10, Christoph Hellwig wrote:
Documentation/ABI/stable/sysfs-block | 42 +++++++++++++++++++
block/blk-settings.c | 60 ++++++++++++++++++++++++++++
block/blk-sysfs.c | 33 +++++++++++++++
include/linux/blkdev.h | 33 +++++++++++++++
4 files changed, 168 insertions(+)
diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
index 1fe9a553c37b..05df7f74cbc1 100644
--- a/Documentation/ABI/stable/sysfs-block
+++ b/Documentation/ABI/stable/sysfs-block
@@ -21,6 +21,48 @@ Description:
device is offset from the internal allocation unit's
natural alignment.
+What: /sys/block/<disk>/atomic_write_max_bytes
+Date: May 2023
+Contact: Himanshu Madhani<himanshu.madhani@xxxxxxxxxx>
+Description:
+ [RO] This parameter specifies the maximum atomic write
+ size reported by the device. An atomic write operation
+ must not exceed this number of bytes.
+What: /sys/block/<disk>/atomic_write_unit_max_bytes
+Date: January 2023
+Contact: Himanshu Madhani<himanshu.madhani@xxxxxxxxxx>
+Description:
+ [RO] This parameter defines the largest block which can be
+ written atomically with an atomic write operation. This
+ value must be a multiple of atomic_write_unit_min and must
+ be a power-of-two.
What is the difference between these two values?
Generally they come from the same device property. Then since
atomic_write_unit_max_bytes must be a power-of-2 (and
atomic_write_max_bytes may not be), they may be different. In addition,
atomic_write_unit_max_bytes is required to be limited by whatever is
guaranteed to be able to fit in a bio.
atomic_write_max_bytes is really only relevant for merging writes. Maybe
we should not even expose via sysfs.
BTW, I do still wonder whether all these values should be limited by
max_sectors_kb (which they aren't currently).
+Date: May 2023
+Contact: Himanshu Madhani<himanshu.madhani@xxxxxxxxxx>
+Description:
+ [RO] This parameter specifies the smallest block which can
+ be written atomically with an atomic write operation. All
+ atomic write operations must begin at a
+ atomic_write_unit_min boundary and must be multiples of
+ atomic_write_unit_min. This value must be a power-of-two.
How can the minimum unit be anythіng but one logical block?
+extern void blk_queue_atomic_write_max_bytes(struct request_queue *q,
+ unsigned int bytes);
Please don't add pointless externs to prototypes in headers.
ok, fine - blkdev.h seems to have a mix for declarations with and
without extern, so at least we would be consistently inconsistent.
+static inline unsigned int queue_atomic_write_unit_max_bytes(const struct request_queue *q)
.. and please avoid the overly long lines.
ok
Thanks,
John
