NTFS-3g capture: sort attributes by starting LCN

[wimlib] / src / ntfs-3g_capture.c

diff --git a/src/ntfs-3g_capture.c b/src/ntfs-3g_capture.c
index 75690917aa6a4dc36fb3c133dd1472c06d69cf46..c0bd9076afeb472801d555a2e53dff3f8d70fcf4 100644 (file)
--- a/src/ntfs-3g_capture.c
+++ b/src/ntfs-3g_capture.c
@@ -168,6 +168,30 @@ attr_type_to_wimlib_stream_type(ATTR_TYPES type)
        }
 }
 
+/* When sorting blobs located in NTFS volumes for sequential reading, we sort
+ * first by starting LCN of the attribute if available, otherwise no sort order
+ * is defined.  This usually results in better sequential access to the volume.
+ */
+static int
+set_attr_sort_key(ntfs_inode *ni, struct ntfs_location *loc)
+{
+       ntfs_attr *na;
+       runlist_element *rl;
+
+       na = open_ntfs_attr(ni, loc);
+       if (!na)
+               return WIMLIB_ERR_NTFS_3G;
+
+       rl = ntfs_attr_find_vcn(na, 0);
+       if (rl && rl->lcn != LCN_HOLE)
+               loc->sort_key = rl->lcn;
+       else
+               loc->sort_key = 0;
+
+       ntfs_attr_close(na);
+       return 0;
+}
+
 /* Save information about an NTFS attribute (stream) to a WIM inode.  */
 static int
 scan_ntfs_attr(struct wim_inode *inode,
@@ -225,6 +249,10 @@ scan_ntfs_attr(struct wim_inode *inode,
                        blob->ntfs_loc->attr_name_nchars = name_nchars;
                }
 
+               ret = set_attr_sort_key(ni, blob->ntfs_loc);
+               if (ret)
+                       goto out_cleanup;
+
                if (unlikely(type == AT_REPARSE_POINT)) {
                        if (blob->size < REPARSE_DATA_OFFSET) {
                                ERROR("Reparse data of \"%s\" "