Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH] splice, net: Fix splice_to_socket() for O_NONBLOCK socket | Date | Mon, 24 Jul 2023 16:44:07 +0100 |
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Jan Stancek <jstancek@redhat.com> wrote:
> On Mon, Jul 24, 2023 at 12:12 PM David Howells <dhowells@redhat.com> wrote: > > > > Jan Stancek <jstancek@redhat.com> wrote: > > > > > LTP sendfile07 [1], which expects sendfile() to return EAGAIN when > > > transferring data from regular file to a "full" O_NONBLOCK socket, > > > started failing after commit 2dc334f1a63a ("splice, net: Use > > > sendmsg(MSG_SPLICE_PAGES) rather than ->sendpage()"). > > > sendfile() no longer immediately returns, but now blocks. > > > > > > Removed sock_sendpage() handled this case by setting a MSG_DONTWAIT > > > flag, fix new splice_to_socket() to do the same for O_NONBLOCK sockets. > > > > Does this actually work correctly in all circumstances? > > > > The problem might come if you have a splice from a non-rewindable source > > through a temporary pipe (eg. sendfile() using splice_direct_to_actor()). > > I assumed this was safe, since sendfile / splice_direct_to_actor() > requires input to be seekable.
Ah! The test isn't where I was looking for it (in sendfile()) - it's in splice_direct_to_actor().
I wonder if it's worth making that explicit in do_sendfile() as the requirement doesn't hold if the output is a pipe (though in such a case, there's an explicit buffer, so it's not actually a problem).
Anyway, did you want to post this to netdev too so that the networking tree picks it up? Feel free to add:
Acked-by: David Howells <dhowells@redhat.com>
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