vfs: fix vmplice_to_user()
Commit 6130f5315ee8 "switch vmsplice_to_user() to copy_page_to_iter()" in
v3.15-rc1 broke vmsplice(2).
This patch fixes two bugs:
- count is not initialized to a proper value, which resulted in no data
being copied
- if rw_copy_check_uvector() returns negative then the iov might be leaked.
Tested OK.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/splice.c b/fs/splice.c
index 9bc07d2..e246954 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1537,7 +1537,7 @@
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter iter;
- ssize_t count = 0;
+ ssize_t count;
pipe = get_pipe_info(file);
if (!pipe)
@@ -1546,8 +1546,9 @@
ret = rw_copy_check_uvector(READ, uiov, nr_segs,
ARRAY_SIZE(iovstack), iovstack, &iov);
if (ret <= 0)
- return ret;
+ goto out;
+ count = ret;
iov_iter_init(&iter, iov, nr_segs, count, 0);
sd.len = 0;
@@ -1560,6 +1561,7 @@
ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
pipe_unlock(pipe);
+out:
if (iov != iovstack)
kfree(iov);