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authorAbhi Das <adas@redhat.com>2016-11-16 21:44:23 -0600
committerAl Viro <viro@zeniv.linux.org.uk>2016-11-17 00:00:48 -0500
commit680bb946a1ae04fe0ff369a4965f76b48c07dc54 (patch)
treebe2ca455a6186b86a08e3ab1c22d49748cc6ed75
parent4a59015372840a6fc35d7fd40638a9d5dc3ec958 (diff)
downloadlinux-680bb946a1ae04fe0ff369a4965f76b48c07dc54.tar.bz2
fix iov_iter_advance() for ITER_PIPE
iov_iter_advance() needs to decrement iter->count by the number of bytes we'd moved beyond. Normal flavours do that, but ITER_PIPE doesn't and ITER_PIPE generic_file_read_iter() for O_DIRECT files ends up with a bogus fallback to page cache read, resulting in incorrect values for file offset and bytes read. Signed-off-by: Abhi Das <adas@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--lib/iov_iter.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index f0c7f1481bae..f2bd21b93dfc 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -683,10 +683,11 @@ static void pipe_advance(struct iov_iter *i, size_t size)
struct pipe_inode_info *pipe = i->pipe;
struct pipe_buffer *buf;
int idx = i->idx;
- size_t off = i->iov_offset;
+ size_t off = i->iov_offset, orig_sz;
if (unlikely(i->count < size))
size = i->count;
+ orig_sz = size;
if (size) {
if (off) /* make it relative to the beginning of buffer */
@@ -713,6 +714,7 @@ static void pipe_advance(struct iov_iter *i, size_t size)
pipe->nrbufs--;
}
}
+ i->count -= orig_sz;
}
void iov_iter_advance(struct iov_iter *i, size_t size)