On 5/12/24 11:39, Andreas Hindborg wrote:
+ /// Set the logical block size of the device.
+ ///
+ /// This is the smallest unit the storage device can address. It is
+ /// typically 512 bytes.
Hmm ... all block devices that I have encountered recently have a
logical block size of 4096 bytes. Isn't this the preferred logical
block size for SSDs and for SMR hard disks?
+ /// Set the physical block size of the device.
+ ///
+ /// This is the smallest unit a physical storage device can write
+ /// atomically. It is usually the same as the logical block size but may be
+ /// bigger. One example is SATA drives with 4KB sectors that expose a
+ /// 512-byte logical block size to the operating system.
Please be consistent and change "4 KB sectors" into "4 KB physical block
size".
I think that the physical block size can also be smaller than the
logical block size. From the SCSI SBC standard:
Table 91 — LOGICAL BLOCKS PER PHYSICAL BLOCK EXPONENT field
----- ------------------------------------------------------------
Code Description
----- ------------------------------------------------------------
0 One or more physical blocks per logical block (the number of
physical blocks per logical block is not reported).
n > 0 2**n logical blocks per physical block
----- ------------------------------------------------------------
+impl<T: Operations, S: GenDiskState> GenDisk<T, S> {
+ /// Call to tell the block layer the capacity of the device in sectors (512B).
Why to use any other unit than bytes in Rust block::mq APIs? sector_t
was introduced before 64-bit CPUs became available to reduce the number
of bytes required to represent offsets. I don't think that this is still
a concern today. Hence my proposal to be consistent in the Rust
block::mq API and to use bytes as the unit in all APIs.
Thanks,
Bart.
