On 1/18/24 8:57 AM, Rich Felker wrote: > On Mon, Aug 31, 2020 at 11:05:34AM -0600, Jens Axboe wrote: >> On 8/31/20 9:46 AM, Jann Horn wrote: >>> On Mon, Aug 31, 2020 at 5:32 PM Rich Felker <dalias@xxxxxxxx> wrote: >>>> The pwrite function, originally defined by POSIX (thus the "p"), is >>>> defined to ignore O_APPEND and write at the offset passed as its >>>> argument. However, historically Linux honored O_APPEND if set and >>>> ignored the offset. This cannot be changed due to stability policy, >>>> but is documented in the man page as a bug. >>>> >>>> Now that there's a pwritev2 syscall providing a superset of the pwrite >>>> functionality that has a flags argument, the conforming behavior can >>>> be offered to userspace via a new flag. Since pwritev2 checks flag >>>> validity (in kiocb_set_rw_flags) and reports unknown ones with >>>> EOPNOTSUPP, callers will not get wrong behavior on old kernels that >>>> don't support the new flag; the error is reported and the caller can >>>> decide how to handle it. >>>> >>>> Signed-off-by: Rich Felker <dalias@xxxxxxxx> >>> >>> Reviewed-by: Jann Horn <jannh@xxxxxxxxxx> >>> >>> Note that if this lands, Michael Kerrisk will probably be happy if you >>> send a corresponding patch for the manpage man2/readv.2. >>> >>> Btw, I'm not really sure whose tree this should go through - VFS is >>> normally Al Viro's turf, but it looks like the most recent >>> modifications to this function have gone through Jens Axboe's tree? >> >> Should probably go through Al's tree, I've only carried them when >> they've been associated with io_uring in some shape or form. > > This appears to have slipped through the cracks. Do I need to send an > updated rebase of it? Were there any objections to it I missed? Let's add Christian. -- Jens Axboe
