[PATCH v2] splice, net: Fix splice_to_socket() for O_NONBLOCK socket

[PATCH v2] splice, net: Fix splice_to_socket() for O_NONBLOCK socket

[Jan Stancek]

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>
---
Changes in v2:
- add David's Acked-by
- add netdev list

 fs/splice.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/splice.c b/fs/splice.c
index 004eb1c4ce31..3e2a31e1ce6a 100644
--- 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);
-- 
2.31.1

Re: [PATCH v2] splice, net: Fix splice_to_socket() for O_NONBLOCK socket

[Xi Ruoyao]

On Mon, 2023-07-24 at 19:39 +0200, Jan Stancek 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.
> 
> [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>

This issue caused the "test_asyncio" test in Python 3 test suite to hang
indefinitely.  I can confirm this patch fixes the issue.

Tested-by: Xi Ruoyao <xry111@xry111.site>

> ---
> Changes in v2:
> - add David's Acked-by
> - add netdev list
> 
>  fs/splice.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/splice.c b/fs/splice.c
> index 004eb1c4ce31..3e2a31e1ce6a 100644
> --- 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);

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH v2] splice, net: Fix splice_to_socket() for O_NONBLOCK socket

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 24 Jul 2023 19:39:04 +0200 you 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.
> 
> [...]

Here is the summary with links:
  - [v2] splice, net: Fix splice_to_socket() for O_NONBLOCK socket
    https://git.kernel.org/netdev/net/c/0f0fa27b871b

You are awesome, thank you!
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