From: Abhi Das Date: Thu, 17 Nov 2016 03:44:23 +0000 (-0600) Subject: fix iov_iter_advance() for ITER_PIPE X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=680bb946a1ae04fe0ff369a4965f76b48c07dc54;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git 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 Signed-off-by: Al Viro --- 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)