From 6f95025c9daf8fb3ed785ff1b650ade5066a58f4 Mon Sep 17 00:00:00 2001
From: Pádraig Brady <P@draigBrady.com>
Date: Tue, 8 Feb 2011 19:16:55 +0000
Subject: copy: suppress redundant lseeks when using fiemap

* src/copy.c (extent_copy): Suppress redundant lseek()s in both
the source and dest files, when there is no hole between extents.
---
 src/copy.c | 40 +++++++++++++++++++---------------------
 1 file changed, 19 insertions(+), 21 deletions(-)

(limited to 'src')

diff --git a/src/copy.c b/src/copy.c
index 9182c1624..5b6ffe334 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -334,33 +334,31 @@ extent_copy (int src_fd, int dest_fd, char *buf, size_t buf_size,
         {
           off_t ext_start = scan.ext_info[i].ext_logical;
           uint64_t ext_len = scan.ext_info[i].ext_length;
+          uint64_t hole_size = ext_start - last_ext_start - last_ext_len;
 
-          if (lseek (src_fd, ext_start, SEEK_SET) < 0)
+          if (hole_size)
             {
-              error (0, errno, _("cannot lseek %s"), quote (src_name));
-            fail:
-              extent_scan_free (&scan);
-              return false;
-            }
+              if (lseek (src_fd, ext_start, SEEK_SET) < 0)
+                {
+                  error (0, errno, _("cannot lseek %s"), quote (src_name));
+                fail:
+                  extent_scan_free (&scan);
+                  return false;
+                }
 
-          if (make_holes)
-            {
-              if (lseek (dest_fd, ext_start, SEEK_SET) < 0)
+              if (make_holes)
                 {
-                  error (0, errno, _("cannot lseek %s"), quote (dst_name));
-                  goto fail;
+                  if (lseek (dest_fd, ext_start, SEEK_SET) < 0)
+                    {
+                      error (0, errno, _("cannot lseek %s"), quote (dst_name));
+                      goto fail;
+                    }
                 }
-            }
-          else
-            {
-              /* When not inducing holes and when there is a hole between
-                 the end of the previous extent and the beginning of the
-                 current one, write zeros to the destination file.  */
-              if (last_ext_start + last_ext_len < ext_start)
+              else
                 {
-                  uint64_t hole_size = (ext_start
-                                        - last_ext_start
-                                        - last_ext_len);
+                  /* When not inducing holes and when there is a hole between
+                     the end of the previous extent and the beginning of the
+                     current one, write zeros to the destination file.  */
                   if (! write_zeros (dest_fd, hole_size))
                     {
                       error (0, errno, _("%s: write failed"), quote (dst_name));
-- 
cgit v1.2.3-54-g00ecf