Hi,
Thanks for this fix. I'd like to reproduce this issue locally and test this
patch,
could you elaborate the detailed steps of reproduction?
Thanks,
Eric
On 08/27/2016 07:04 AM, Ashish Samant wrote:
> If we punch a hole on a reflink such that following conditions are met:
>
> 1. start offset is on a cluster boundary
> 2. end offset is not on a cluster boundary
> 3. (end offset is somewhere in another extent) or
> (hole range > MAX_CONTIG_BYTES(1MB)),
>
> we dont COW the first cluster starting at the start offset. But in this
> case, we were wrongly passing this cluster to
> ocfs2_zero_range_for_truncate() to zero out. This will modify the cluster
> in place and zero it in the source too.
>
> Fix this by skipping this cluster in such a scenario.
>
> Reported-by: Saar Maoz <saar.m...@oracle.com>
> Signed-off-by: Ashish Samant <ashish.sam...@oracle.com>
> Reviewed-by: Srinivas Eeda <srinivas.e...@oracle.com>
> ---
> v1->v2:
> -Changed the commit msg to include a better and generic description of
> the problem, for all cluster sizes.
> -Added Reported-by and Reviewed-by tags.
>
> fs/ocfs2/file.c | 34 ++++++++++++++++++++++++----------
> 1 file changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 4e7b0dc..0b055bf 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -1506,7 +1506,8 @@ static int ocfs2_zero_partial_clusters(struct inode
> *inode,
> u64 start, u64 len)
> {
> int ret = 0;
> - u64 tmpend, end = start + len;
> + u64 tmpend = 0;
> + u64 end = start + len;
> struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> unsigned int csize = osb->s_clustersize;
> handle_t *handle;
> @@ -1538,18 +1539,31 @@ static int ocfs2_zero_partial_clusters(struct inode
> *inode,
> }
>
> /*
> - * We want to get the byte offset of the end of the 1st cluster.
> + * If start is on a cluster boundary and end is somewhere in another
> + * cluster, we have not COWed the cluster starting at start, unless
> + * end is also within the same cluster. So, in this case, we skip this
> + * first call to ocfs2_zero_range_for_truncate() truncate and move on
> + * to the next one.
> */
> - tmpend = (u64)osb->s_clustersize + (start & ~(osb->s_clustersize - 1));
> - if (tmpend > end)
> - tmpend = end;
> + if ((start & (csize - 1)) != 0) {
> + /*
> + * We want to get the byte offset of the end of the 1st
> + * cluster.
> + */
> + tmpend = (u64)osb->s_clustersize +
> + (start & ~(osb->s_clustersize - 1));
> + if (tmpend > end)
> + tmpend = end;
>
> - trace_ocfs2_zero_partial_clusters_range1((unsigned long long)start,
> - (unsigned long long)tmpend);
> + trace_ocfs2_zero_partial_clusters_range1(
> + (unsigned long long)start,
> + (unsigned long long)tmpend);
>
> - ret = ocfs2_zero_range_for_truncate(inode, handle, start, tmpend);
> - if (ret)
> - mlog_errno(ret);
> + ret = ocfs2_zero_range_for_truncate(inode, handle, start,
> + tmpend);
> + if (ret)
> + mlog_errno(ret);
> + }
>
> if (tmpend < end) {
> /*
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