[Libguestfs] [PATCH v2 1/5] uuid: add support to change uuid of btrfs partition

[Chen Hanxiao]

btrfs-progs v4.1 add support to change uuid of btrfs fs.

Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
---
v2: put btrfs operation back to daemon/btrfs.c
    move tests to tests/btrfs

 daemon/btrfs.c                 | 60 ++++++++++++++++++++++++++++++++++++++++++
 daemon/daemon.h                |  1 +
 daemon/uuids.c                 |  9 +++++--
 tests/btrfs/test-btrfs-misc.pl |  6 +++++
 4 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/daemon/btrfs.c b/daemon/btrfs.c
index 20e5e6b..b82c1b9 100644
--- a/daemon/btrfs.c
+++ b/daemon/btrfs.c
@@ -790,6 +790,44 @@ do_btrfs_device_delete (char *const *devices, const char *fs)
   return 0;
 }
 
+
+/* btrfstune command add two new options
+ * -U UUID      change fsid to UUID
+ * -u           change fsid, use a random one
+ * since v4.1
+ * We could check wheter 'btrfstune' support
+ * '-u' and '-U UUID' option by checking the output of
+ * 'btrfstune' command.
+ */
+static int
+test_btrftune_uuid_opt (void)
+{
+  static int result = -1;
+  if (result != -1)
+    return result;
+
+  CLEANUP_FREE char *err = NULL;
+
+  int r = commandr (NULL, &err, str_btrfstune, NULL);
+
+  if (r == -1) {
+    reply_with_error ("btrfstune: %s", err);
+    return -1;
+  }
+
+  /* FIXME currently btrfstune do not support '--help'.
+   * If got an invalid options, it will print its usage
+   * in stderr.
+   * We had to check it there.
+   */
+  if (strstr (err, "-U") == NULL || strstr (err, "-u") == NULL)
+    result = 0;
+  else
+    result = 1;
+
+  return result;
+}
+
 int
 do_btrfs_set_seeding (const char *device, int svalue)
 {
@@ -807,6 +845,28 @@ do_btrfs_set_seeding (const char *device, int svalue)
   return 0;
 }
 
+int
+btrfstune_set_uuid (const char *device, const char *uuid)
+{
+  CLEANUP_FREE char *err = NULL;
+  int r;
+  int has_uuid_opts = test_btrftune_uuid_opt ();
+
+  if (has_uuid_opts == 0) {
+    reply_with_error ("btrfstune do not support '-u'");
+    return -1;
+  }
+
+  r = commandr (NULL, &err, str_btrfstune, "-f", "-U", uuid, device, NULL);
+
+  if (r == -1) {
+    reply_with_error ("%s: %s", device, err);
+    return -1;
+  }
+
+  return 0;
+}
+
 /* Takes optional arguments, consult optargs_bitmask. */
 int
 do_btrfs_fsck (const char *device, int64_t superblock, int repair)
diff --git a/daemon/daemon.h b/daemon/daemon.h
index 136e9a9..ee0c96f 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -268,6 +268,7 @@ extern char *debug_bmap_device (const char *subcmd, size_t argc, char *const *co
 
 /*-- in btrfs.c --*/
 extern char *btrfs_get_label (const char *device);
+extern int btrfstune_set_uuid (const char *device, const char *uuid);
 
 /*-- in ntfs.c --*/
 extern char *ntfs_get_label (const char *device);
diff --git a/daemon/uuids.c b/daemon/uuids.c
index 06b33e9..f7791ab 100644
--- a/daemon/uuids.c
+++ b/daemon/uuids.c
@@ -91,6 +91,12 @@ swapuuid (const char *device, const char *uuid)
   return 0;
 }
 
+static int
+btrfsuuid (const char *device, const char *uuid)
+{
+  return btrfstune_set_uuid (device, uuid);
+}
+
 int
 do_set_uuid (const char *device, const char *uuid)
 {
@@ -111,8 +117,7 @@ do_set_uuid (const char *device, const char *uuid)
     r = swapuuid (device, uuid);
 
   else if (STREQ (vfs_type, "btrfs")) {
-    reply_with_error ("btrfs filesystems' UUID cannot be changed");
-    r = -1;
+    r = btrfsuuid (device, uuid);
   }
 
   else {
diff --git a/tests/btrfs/test-btrfs-misc.pl b/tests/btrfs/test-btrfs-misc.pl
index 2fe7c59..cd60990 100755
--- a/tests/btrfs/test-btrfs-misc.pl
+++ b/tests/btrfs/test-btrfs-misc.pl
@@ -47,5 +47,11 @@ my $label = $g->vfs_label ("/dev/sda1");
 die "unexpected label: expecting 'newlabel' but got '$label'"
     unless $label eq "newlabel";
 
+# Setting btrfs UUID
+$g->set_uuid ("/dev/sda1", "12345678-1234-1234-1234-123456789012");
+my $uuid = $g->vfs_uuid ("/dev/sda1");
+die "unexpected label: expecting 'newlabel' but got '$uuid'"
+    unless $uuid eq "12345678-1234-1234-1234-123456789012";
+
 $g->shutdown ();
 $g->close ();
-- 
2.1.0