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) {
/*
--
1.9.1
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel
