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? Rich
