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SubjectRe: [PATCH] Ceph: Avoid data inconsistency due to d-cache aliasing in readpage()
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On Wed, Nov 13, 2013 at 3:22 PM, Li Wang <liwang@ubuntukylin.com> wrote:
> If the length of data to be read in readpage() is exactly
> PAGE_CACHE_SIZE, the original code does not flush d-cache
> for data consistency after finishing reading. This patches fixes
> this.
>
> Signed-off-by: Li Wang <liwang@ubuntukylin.com>
> ---
> fs/ceph/addr.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index 6df8bd4..7b0000a 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -210,9 +210,13 @@ static int readpage_nounlock(struct file *filp, struct page *page)
> if (err < 0) {
> SetPageError(page);
> goto out;
> - } else if (err < PAGE_CACHE_SIZE) {
> + } else {
> + if (err < PAGE_CACHE_SIZE) {
> /* zero fill remainder of page */
> - zero_user_segment(page, err, PAGE_CACHE_SIZE);
> + zero_user_segment(page, err, PAGE_CACHE_SIZE);
> + } else {
> + flush_dcache_page(page);
> + }

this doesn't make sense for me. why not call flush_dcache_page unconditionally?

Regards
Yan, Zheng
> }
> SetPageUptodate(page);
>
> --
> 1.7.9.5
>
> --
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