splice, net: Fix splice_to_socket() for O_NONBLOCK socket

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.

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/sendfile/sendfile07.c

Fixes: 2dc334f1a63a ("splice, net: Use sendmsg(MSG_SPLICE_PAGES) rather than ->sendpage()")
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Xi Ruoyao <xry111@xry111.site>
Link: https://lore.kernel.org/r/023c0e21e595e00b93903a813bc0bfb9a5d7e368.1690219914.git.jstancek@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/fs/splice.c b/fs/splice.c
index 004eb1c4ce318c9e7e74b49f272e1e033a4a4fa1..3e2a31e1ce6a8f899287ec959fe85328371b38f0 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -876,6 +876,8 @@ ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out,
                        msg.msg_flags |= MSG_MORE;
                if (remain && pipe_occupancy(pipe->head, tail) > 0)
                        msg.msg_flags |= MSG_MORE;
+               if (out->f_flags & O_NONBLOCK)
+                       msg.msg_flags |= MSG_DONTWAIT;
 
                iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, bvec, bc,
                              len - remain);