On Mon, Apr 06, 2015 at 08:04:01PM +0000, Drokin, Oleg wrote:
> Hello!
>
> On Apr 6, 2015, at 12:02 PM, Al Viro wrote:
> > 2) should we ever update the current position when write() returns 0?
> > IOW, what effect should zero-length write() on O_APPEND file have upon its
> > current position? POSIX seems to imply that it should do nothing, and
> > generally that's what happens, but e.g. ext4 *does* update position to
> > the EOF, whether we will write anything or not. So does FUSE when server
> > requests to bypass the page cache. AFAICS, lustre is the same way,
> > but I might be missing something; everything else definitely does not
>
> Lustre is not the same way.
> drivers/staging/lustre/lustre/llite/file.c::ll_file_io_generic() has this
> if (io-> ci_nob > 0) {
> result = io->ci_nob;
> *ppos = io->u.ci_wr.wr.crw_pos;
> }
>
> and ppos is passed in as &iocb->ki_pos. ci_nob is number of bytes that we managed to read/write,
> and if it was 0 (either due to 0 bytes io request or due to error from the get go)
> we won't update it.
Eh? vvp_io_write_start():
result = generic_file_write_iter(cio->cui_iocb, cio->cui_iter);
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