Merge tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull copy_to_iter_mc fix from Al Viro:
 "Backportable fix for copy_to_iter_mc() - the second part of iov_iter
  work will pretty much overwrite this, but would be much harder to
  backport"

* tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fix short copy handling in copy_mc_pipe_to_iter()

1 files changed, 11 insertions, 4 deletions

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 58648fcd9a88..0e0be334dbee 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -521,6 +521,7 @@ static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
 	struct pipe_inode_info *pipe = i->pipe;
 	unsigned int p_mask = pipe->ring_size - 1;
 	unsigned int i_head;
+	unsigned int valid = pipe->head;
 	size_t n, off, xfer = 0;
 
 	if (!sanity(i))
@@ -534,11 +535,17 @@ static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
 		rem = copy_mc_to_kernel(p + off, addr + xfer, chunk);
 		chunk -= rem;
 		kunmap_local(p);
-		i->head = i_head;
-		i->iov_offset = off + chunk;
-		xfer += chunk;
-		if (rem)
+		if (chunk) {
+			i->head = i_head;
+			i->iov_offset = off + chunk;
+			xfer += chunk;
+			valid = i_head + 1;
+		}
+		if (rem) {
+			pipe->bufs[i_head & p_mask].len -= rem;
+			pipe_discard_from(pipe, valid);
 			break;
+		}
 		n -= chunk;
 		off = 0;
 		i_head++;