[PATCH v2 6/7] vmsplice: return -EINVAL for particular combination of flags

[Askar Safin <safinaskar@gmail.com>]

See comment for details.

Signed-off-by: Askar Safin <safinaskar@gmail.com>
---
 fs/read_write.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/read_write.c b/fs/read_write.c
index dbd0debc2..b1f71b142 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1258,6 +1258,16 @@ SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, vec,
 		bool non_block = (flags & SPLICE_F_NONBLOCK) || (fd_file(f)->f_flags & O_NONBLOCK);
 		ssize_t ret;
 
+		/*
+		 * libfuse relies on sharing vmsplice behavior.
+		 * So we detect particular combination of flags to
+		 * pipe2(2) and vmsplice(2) and return -EINVAL.
+		 * This forces libfuse to fail back to non-vmsplice
+		 * code path.
+		 */
+		if ((flags == SPLICE_F_NONBLOCK) && (fd_file(f)->f_flags & O_NONBLOCK))
+			return -EINVAL;
+
 		do {
 			pipe_lock(pipe);
 			ret = pipe_wait_for_space(pipe, non_block);
-- 
2.47.3