On 2012-05-10, at 11:10 AM, Roland McGrath wrote:
POSIX specifies st_blksize thusly: "A file system-specific preferred
I/O block size for this object. In some file system types, this may
vary from file to file."
Since there is only one available to POSIX applications, it should map
to the one that's described as "preferred IO size for general usage".
Sure, but statxat() isn't a POSIX API.
While I agree with the idea that there should be enough information about the underlying layout for applications to be able to submit good IO, it doesn't help if we have a bunch of extra fields that have vague meanings.
They will get filled in by the filesystem in a haphazard way, and will not be used by application developers that don't understand what they mean.
Cheers, Andreas