fs/ntfs3: Refactoring attr_punch_hole to restore after errors

Added comments to code
Added new function run_clone to make a copy of run
Added done and undo labels for restoring after errors

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/fs/ntfs3/run.c b/fs/ntfs3/run.c
index 987a150108df..aaaa0d3d35a2 100644
--- a/fs/ntfs3/run.c
+++ b/fs/ntfs3/run.c
@@ -1156,3 +1156,28 @@ int run_get_highest_vcn(CLST vcn, const u8 *run_buf, u64 *highest_vcn)
 	*highest_vcn = vcn64 - 1;
 	return 0;
 }
+
+/*
+ * run_clone
+ *
+ * Make a copy of run
+ */
+int run_clone(const struct runs_tree *run, struct runs_tree *new_run)
+{
+	size_t bytes = run->count * sizeof(struct ntfs_run);
+
+	if (bytes > new_run->allocated) {
+		struct ntfs_run *new_ptr = kvmalloc(bytes, GFP_KERNEL);
+
+		if (!new_ptr)
+			return -ENOMEM;
+
+		kvfree(new_run->runs);
+		new_run->runs = new_ptr;
+		new_run->allocated = bytes;
+	}
+
+	memcpy(new_run->runs, run->runs, bytes);
+	new_run->count = run->count;
+	return 0;
+}