Hello Liu,

thanks, you are so right. I just got it exactly the wrong way (I read
btrfs-progs-unstable and thought this must be the bleeding edge one
;-). I should have read your e-Mail before.
I will revise it asap. But I have to let it wait for tomorrow... Gotta
sleep now.

Best Regards,
Alex


2012/7/31 Liu Bo [off-list ref]:

On 07/31/2012 08:53 AM, Alexander Karbstein wrote:

quoted

The command btrfs subvolume set-default 0 /path/to/fs changed the
default subvolume to whatever subvolume was currently mounted on
/path/to/fs. This patch changes this behaviour to set the default
subvolume to BTRFS_FS_TREE_OBJECTID in case the user asks for
subvolid=0

quoted

Signed-off-by: Alexander Karbstein <redacted>
---
 btrfs_cmds.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/btrfs_cmds.c b/btrfs_cmds.c
index f2b6355..699d9b0 100644
--- a/btrfs_cmds.c
+++ b/btrfs_cmds.c

@@ -964,6 +964,11 @@ int do_set_default_subvol(int nargs, char **argv)
              fprintf(stderr, "ERROR: invalid tree id (%s)\n",subvolid);
              return 30;
      }
+
+     /* Using the original root fs tree */
+     if (objectid == 0ULL) {
+             objectid = BTRFS_FS_TREE_OBJECTID;
+     }
      ret = ioctl(fd, BTRFS_IOC_DEFAULT_SUBVOL, &objectid);
      e = errno;
      close(fd);

Seems that you're using an old btrfs-prog source code, now the file is cmds-subvolume.c

And also checkpatch.pl complains about style errors while checking this.

thanks,
liubo