As currently st_blksize is always PAGE_SIZE, it is playing safe to not
use any smaller value. For some cases this might not be optimal, but
at least nothing should get broken.
Generally I don't expect this commit to change much for the following
reasons (in case of VREG, VDIR):
- application I/O and physical I/O are sufficiently decoupled by
filesystem code, buffer cache code, cluster and read-ahead logic
- not all applications use st_blksize as a hint, some use f_iosize, some
use fixed block sizes
I expect writes to the middle of files on ZFS to benefit the most from
this change.
Silence from: fs@
MFC after: 2 weeks
364b8a7b33