overlay: skip superfluous metadata sets on commit

burke · burke · commit bc5503f46bdc · 2015-05-07T16:15:54.000-04:00
Signed-off-by: Burke Libbey &lt;burke.libbey@shopify.com&gt;
diff --git a/daemon/graphdriver/overlay/copy.go b/daemon/graphdriver/overlay/copy.go
@@ -71,9 +71,12 @@ func copyDir(srcDir, dstDir string, flags CopyFlags) error {
 			return fmt.Errorf("Unable to get raw syscall.Stat_t data for %s", srcPath)
 		}
 
+		isHardlink := false
+
 		switch f.Mode() & os.ModeType {
 		case 0: // Regular file
 			if flags&CopyHardlink != 0 {
+				isHardlink = true
 				if err := os.Link(srcPath, dstPath); err != nil {
 					return err
 				}
@@ -114,6 +117,12 @@ func copyDir(srcDir, dstDir string, flags CopyFlags) error {
 			return fmt.Errorf("Unknown file type for %s\n", srcPath)
 		}
 
+		// Everything below is copying metadata from src to dst. All this metadata
+		// already shares an inode for hardlinks.
+		if isHardlink {
+			return nil
+		}
+
 		if err := os.Lchown(dstPath, int(stat.Uid), int(stat.Gid)); err != nil {
 			return err
 		}

Original file line number	Diff line number	Diff line change
`@@ -71,9 +71,12 @@ func copyDir(srcDir, dstDir string, flags CopyFlags) error {`
`71`	`71`	`return fmt.Errorf("Unable to get raw syscall.Stat_t data for %s", srcPath)`
`72`	`72`	`}`
`73`	`73`
	`74`	`+ isHardlink := false`
	`75`	`+`
`74`	`76`	`switch f.Mode() & os.ModeType {`
`75`	`77`	`case 0: // Regular file`
`76`	`78`	`if flags&CopyHardlink != 0 {`
	`79`	`+ isHardlink = true`
`77`	`80`	`if err := os.Link(srcPath, dstPath); err != nil {`
`78`	`81`	`return err`
`79`	`82`	`}`
`@@ -114,6 +117,12 @@ func copyDir(srcDir, dstDir string, flags CopyFlags) error {`
`114`	`117`	`return fmt.Errorf("Unknown file type for %s\n", srcPath)`
`115`	`118`	`}`
`116`	`119`
	`120`	`+ // Everything below is copying metadata from src to dst. All this metadata`
	`121`	`+ // already shares an inode for hardlinks.`
	`122`	`+ if isHardlink {`
	`123`	`+ return nil`
	`124`	`+ }`
	`125`	`+`
`117`	`126`	`if err := os.Lchown(dstPath, int(stat.Uid), int(stat.Gid)); err != nil {`
`118`	`127`	`return err`
`119`	`128`	`}`