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>
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index f0c7f14..f2bd21b 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -683,10 +683,11 @@
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 @@
pipe->nrbufs--;
}
}
+ i->count -= orig_sz;
}
void iov_iter_advance(struct iov_iter *i, size_t size)