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Commit 680bb946 authored by Abhi Das's avatar Abhi Das Committed by Al Viro
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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: default avatarAbhi Das <adas@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 4a590153

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)