[Ocfs2-tools-devel] [PATCH 25/44] libocfs2: Add function for punch hole in refcount tree.

[Tao Ma]

In fsck.ocfs2, sometimes we need to remove the refcount
from the tree, so this patch add a new function named
ocfs2_refcount_punch_hole which will do like this.
Since the old ocfs2_split_refcount_rec is implemented
to handle the case r_refcount=0, so it is quite easy
for us to punch a hole.

Signed-off-by: Tao Ma <tao.ma at oracle.com>
---
 include/ocfs2/ocfs2.h |    2 +
 libocfs2/refcount.c   |   55 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 0 deletions(-)

diff --git a/include/ocfs2/ocfs2.h b/include/ocfs2/ocfs2.h
index e8173ca..6589523 100644
--- a/include/ocfs2/ocfs2.h
+++ b/include/ocfs2/ocfs2.h
@@ -430,6 +430,8 @@ errcode_t ocfs2_refcount_tree_get_rec(ocfs2_filesys *fs,
 				      uint64_t *p_blkno,
 				      uint32_t *e_cpos,
 				      uint32_t *num_clusters);
+errcode_t ocfs2_refcount_punch_hole(ocfs2_filesys *fs, uint64_t rf_blkno,
+				    uint64_t p_start, uint32_t len);
 errcode_t ocfs2_swap_dir_entries_from_cpu(void *buf, uint64_t bytes);
 errcode_t ocfs2_swap_dir_entries_to_cpu(void *buf, uint64_t bytes);
 void ocfs2_swap_dir_trailer(struct ocfs2_dir_block_trailer *trailer);
diff --git a/libocfs2/refcount.c b/libocfs2/refcount.c
index 3b437fb..38800fd 100644
--- a/libocfs2/refcount.c
+++ b/libocfs2/refcount.c
@@ -1885,6 +1885,61 @@ out:
 	return ret;
 }
 
+errcode_t ocfs2_refcount_punch_hole(ocfs2_filesys *fs, uint64_t rf_blkno,
+				    uint64_t p_start, uint32_t len)
+{
+	errcode_t ret;
+	char *root_buf = NULL, *buf = NULL;
+	struct ocfs2_refcount_rec rec;
+	int index;
+	struct ocfs2_refcount_block *root_rb, *rb;
+
+	ret = ocfs2_malloc_block(fs->fs_io, &root_buf);
+	if (ret)
+		goto out;
+
+	ret = ocfs2_malloc_block(fs->fs_io, &buf);
+	if (ret)
+		goto out;
+
+	ret = ocfs2_read_refcount_block(fs, rf_blkno, root_buf);
+	if (ret)
+		goto out;
+
+	root_rb = (struct ocfs2_refcount_block *)root_buf;
+	rb = (struct ocfs2_refcount_block *)buf;
+	while (len) {
+		ret = ocfs2_get_refcount_rec(fs, root_buf, p_start,
+					     len, &rec, &index, buf);
+		if (!rec.r_refcount) {
+			/* There is no refcount for p_start. */
+			len -= rec.r_clusters;
+			p_start += rec.r_clusters;
+			continue;
+		}
+
+		rec.r_clusters = (p_start + len < rec.r_cpos + rec.r_clusters) ?
+				  len : (rec.r_cpos + rec.r_clusters - p_start);
+		rec.r_cpos = p_start;
+		rec.r_refcount = 0;
+		ret = ocfs2_split_refcount_rec(fs, root_buf, buf,
+					       &rec, index, 1);
+		if (ret)
+			goto out;
+		len -= rec.r_clusters;
+		p_start += rec.r_clusters;
+		/* In user space, we have to sync the buf by ourselves. */
+		if (rb->rf_blkno == root_rb->rf_blkno)
+			memcpy(root_buf, buf, fs->fs_blocksize);
+	}
+out:
+	if (root_buf)
+		ocfs2_free(&root_buf);
+	if (buf)
+		ocfs2_free(&buf);
+	return ret;
+}
+
 struct xattr_value_cow_object {
 	struct ocfs2_xattr_value_root *xv;
 	uint64_t xe_blkno;
-- 
1.5.5