On Mon, 2013-11-25 at 00:42 +0100, Richard Weinberger wrote:

quoted

Commit 35f9c09fe (tcp: tcp_sendpages() should call tcp_push() once)
added an internal flag MSG_SENDPAGE_NOTLAST.
We have to ensure that MSG_MORE is also set if we set MSG_SENDPAGE_NOTLAST.
Otherwise users that check against MSG_MORE will not see it.

This fixes sendfile() on AF_ALG.

Cc: Tom Herbert <redacted>
Cc: Eric Dumazet <redacted>
Cc: David S. Miller <davem@davemloft.net>
Cc: <redacted> # 3.4.x
Reported-and-tested-by: Shawn Landden <redacted>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 fs/splice.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/splice.c b/fs/splice.c
index 3b7ee65..b93f1b8 100644
--- a/fs/splice.c
+++ b/fs/splice.c

@@ -701,7 +701,7 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe,
      more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;

      if (sd->len < sd->total_len && pipe->nrbufs > 1)
-             more |= MSG_SENDPAGE_NOTLAST;
+             more |= MSG_SENDPAGE_NOTLAST | MSG_MORE;

      return file->f_op->sendpage(file, buf->page, buf->offset,
                                  sd->len, &pos, more);

I do not think this patch is right. It looks like a revert of a useful
patch for TCP zero copy. Given the time it took to discover this
regression, I bet tcp zero copy has more users than AF_ALG, by 5 or 6
order of magnitude ;)

Here we want to make the difference between the two flags, not merge
them.

If AF_ALG do not care of the difference, try instead :

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index ef5356cd280a..850246206b12 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c

@@ -114,6 +114,9 @@ static ssize_t hash_sendpage(struct socket *sock, struct page *page,
        struct hash_ctx *ctx = ask->private;
        int err;

+       if (flags & MSG_SENDPAGE_NOTLAST)
+               flags |= MSG_MORE;
+
        lock_sock(sk);
        sg_init_table(ctx->sgl.sg, 1);
        sg_set_page(ctx->sgl.sg, page, size, offset);