ocfs2: support partial clone range and dedupe range

Change the ocfs2 remap code to allow for returning partial results.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/ocfs2/file.c

@@ -2531,14 +2531,11 @@ static loff_t ocfs2_remap_file_range(struct file *file_in, loff_t pos_in,
 				     struct file *file_out, loff_t pos_out,
 				     loff_t len, unsigned int remap_flags)
 {
-	int ret;
-
 	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
 
-	ret = ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
+	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
 			len, remap_flags);
-	return ret < 0 ? ret : len;
 }
 
 const struct inode_operations ocfs2_file_iops = {

fs/ocfs2/refcounttree.c

@@ -4507,7 +4507,7 @@ static int ocfs2_reflink_update_dest(struct inode *dest,
 }
 
 /* Remap the range pos_in:len in s_inode to pos_out:len in t_inode. */
-static int ocfs2_reflink_remap_extent(struct inode *s_inode,
+static loff_t ocfs2_reflink_remap_extent(struct inode *s_inode,
 					 struct buffer_head *s_bh,
 					 loff_t pos_in,
 					 struct inode *t_inode,
@@ -4522,8 +4522,9 @@ static int ocfs2_reflink_remap_extent(struct inode *s_inode,
 	struct buffer_head *ref_root_bh = NULL;
 	struct ocfs2_refcount_tree *ref_tree;
 	struct ocfs2_super *osb;
+	loff_t remapped_bytes = 0;
 	loff_t pstart, plen;
-	u32 p_cluster, num_clusters, slast, spos, tpos;
+	u32 p_cluster, num_clusters, slast, spos, tpos, remapped_clus = 0;
 	unsigned int ext_flags;
 	int ret = 0;
 
@@ -4605,18 +4606,22 @@ static int ocfs2_reflink_remap_extent(struct inode *s_inode,
 next_loop:
 		spos += num_clusters;
 		tpos += num_clusters;
+		remapped_clus += num_clusters;
 	}
 
-out:
-	return ret;
+	goto out;
 out_unlock_refcount:
 	ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
 	brelse(ref_root_bh);
-	return ret;
+out:
+	remapped_bytes = ocfs2_clusters_to_bytes(t_inode->i_sb, remapped_clus);
+	remapped_bytes = min_t(loff_t, len, remapped_bytes);
+
+	return remapped_bytes > 0 ? remapped_bytes : ret;
 }
 
 /* Set up refcount tree and remap s_inode to t_inode. */
-static int ocfs2_reflink_remap_blocks(struct inode *s_inode,
+static loff_t ocfs2_reflink_remap_blocks(struct inode *s_inode,
 					 struct buffer_head *s_bh,
 					 loff_t pos_in,
 					 struct inode *t_inode,
@@ -4628,7 +4633,7 @@ static int ocfs2_reflink_remap_blocks(struct inode *s_inode,
 	struct ocfs2_super *osb;
 	struct ocfs2_dinode *dis;
 	struct ocfs2_dinode *dit;
-	int ret;
+	loff_t ret;
 
 	osb = OCFS2_SB(s_inode->i_sb);
 	dis = (struct ocfs2_dinode *)s_bh->b_data;
@@ -4700,7 +4705,7 @@ static int ocfs2_reflink_remap_blocks(struct inode *s_inode,
 	/* Actually remap extents now. */
 	ret = ocfs2_reflink_remap_extent(s_inode, s_bh, pos_in, t_inode, t_bh,
 					 pos_out, len, &dealloc);
-	if (ret) {
+	if (ret < 0) {
 		mlog_errno(ret);
 		goto out;
 	}
@@ -4820,7 +4825,7 @@ static void ocfs2_reflink_inodes_unlock(struct inode *s_inode,
 }
 
 /* Link a range of blocks from one file to another. */
-int ocfs2_reflink_remap_range(struct file *file_in,
+loff_t ocfs2_reflink_remap_range(struct file *file_in,
 				 loff_t pos_in,
 				 struct file *file_out,
 				 loff_t pos_out,
@@ -4832,6 +4837,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 	struct ocfs2_super *osb = OCFS2_SB(inode_in->i_sb);
 	struct buffer_head *in_bh = NULL, *out_bh = NULL;
 	bool same_inode = (inode_in == inode_out);
+	loff_t remapped = 0;
 	ssize_t ret;
 
 	if (!ocfs2_refcount_tree(osb))
@@ -4866,12 +4872,13 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 				   round_down(pos_out, PAGE_SIZE),
 				   round_up(pos_out + len, PAGE_SIZE) - 1);
 
-	ret = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in, inode_out,
-					 out_bh, pos_out, len);
+	remapped = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in,
+			inode_out, out_bh, pos_out, len);
 	up_write(&OCFS2_I(inode_in)->ip_alloc_sem);
 	if (!same_inode)
 		up_write(&OCFS2_I(inode_out)->ip_alloc_sem);
-	if (ret) {
+	if (remapped < 0) {
+		ret = remapped;
 		mlog_errno(ret);
 		goto out_unlock;
 	}
@@ -4889,10 +4896,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 		goto out_unlock;
 	}
 
-	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
-	return 0;
-
 out_unlock:
 	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
-	return ret;
+	return remapped > 0 ? remapped : ret;
 }

fs/ocfs2/refcounttree.h

@@ -115,7 +115,7 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 			const char __user *oldname,
 			const char __user *newname,
 			bool preserve);
-int ocfs2_reflink_remap_range(struct file *file_in,
+loff_t ocfs2_reflink_remap_range(struct file *file_in,
 				 loff_t pos_in,
 				 struct file *file_out,
 				 loff_t pos_out,