Re: [RFC][PATCH 10/13] make dump_emit() use vfs_write() instead ofbanging at ->f_op->write directly

[Linus Torvalds]

On Tue, Oct 8, 2013 at 6:18 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> Point, but I would argue that we should yell very loud if we get 0 from
> vfs_write() for non-zero size.  I'm not sure if POSIX allows write(2)
> to return that, but a lot of userland code won't be expecting that and
> won't be able to cope...

Actually POSIX very much allows zero returns. O_NDELAY is mentioned as
a possible cause, in addition to zero-sized writes themselves, of
course.

Also, writing to (but not past) the end of a block device returns 0
for "end of device", iirc.

                Linus
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