On 12/18/23 15:08, Douglas Gilbert wrote:
On 12/18/23 13:56, Bart Van Assche wrote:
Changes compared to v6:
- Dropped patch "fs: Restore F_[GS]ET_FILE_RW_HINT support".
That leaves us with F_SET_RW_HINT and F_GET_RW_HINT ioctls. Could you please
explain, perhaps with an example, what functionality is lost and what we still
have?
Hmm ... what information do you expect that is not available in the fcntl man
page? From that man page:
F_SET_RW_HINT (uint64_t *; since Linux 4.13)
Sets the read/write hint value associated with the underlying inode re‐
ferred to by fd. This hint persists until either it is explicitly mod‐
ified or the underlying filesystem is unmounted.
F_SET_FILE_RW_HINT (uint64_t *; since Linux 4.13)
Sets the read/write hint value associated with the open file descrip‐
tion referred to by fd.
The functionality that is lost is to open a file multiple times and to call
F_SET_FILE_RW_HINT with a different value for each file. Ceph used this approach
to specify R/W hints per LBA range in combination with direct I/O.
Bart.
