Ashish Samant
2016-Aug-26 23:04 UTC
[Ocfs2-devel] [PATCH v2] ocfs2: Fix start offset to ocfs2_zero_range_for_truncate()
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.maoz at oracle.com>
Signed-off-by: Ashish Samant <ashish.samant at oracle.com>
Reviewed-by: Srinivas Eeda <srinivas.eeda at 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
Eric Ren
2016-Aug-29 05:39 UTC
[Ocfs2-devel] [PATCH v2] ocfs2: Fix start offset to ocfs2_zero_range_for_truncate()
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.maoz at oracle.com> > Signed-off-by: Ashish Samant <ashish.samant at oracle.com> > Reviewed-by: Srinivas Eeda <srinivas.eeda at 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) { > /*