fix iov_iter_advance() for ITER_PIPE (680bb946) · Commits · 戴 / test

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>

lib/iov_iter.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -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)

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