Why does btrfs send /mnt/btrfs-root fail with ERROR: /mnt/btrfs-root is not read-only. even when mounted with option ro?

2013-02-16 Thread Adam Ryczkowski 

Question as in title.

I did remount my btrfs partition as read-only

(i.e. I did sudo mount /dev/sda9 /mnt/btrfs-root -o ro)

And when I did
  btrfs send /mnt/btrfs-root /dev/null
I received ERROR: /mnt/adama-docs is not read-only.

Although, when I
  sudo touch /mnt/btrfs-root/foo
I get touch: cannot touch `/mnt/btrfs-root/foo': Read-only file system


My btrfs --version reads
  Btrfs v0.20-rc1-56-g6cd836d

And uname -r
  3.7.8-030708-generic

Do I miss something obvious? Or should I wait until next kernel version?

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Adam Ryczkowski
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Skype:sisteczko

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Re: Why does btrfs send /mnt/btrfs-root fail with ERROR: /mnt/btrfs-root is not read-only. even when mounted with option ro?

2013-02-16 Thread Hugo Mills 
On Sat, Feb 16, 2013 at 11:07:28PM +0100, Adam Ryczkowski wrote:
 Question as in title.
 
 I did remount my btrfs partition as read-only
 
 (i.e. I did sudo mount /dev/sda9 /mnt/btrfs-root -o ro)
 
 And when I did
   btrfs send /mnt/btrfs-root /dev/null
 I received ERROR: /mnt/adama-docs is not read-only.
 
 Although, when I
   sudo touch /mnt/btrfs-root/foo
 I get touch: cannot touch `/mnt/btrfs-root/foo': Read-only file system
 
 
 My btrfs --version reads
   Btrfs v0.20-rc1-56-g6cd836d
 
 And uname -r
   3.7.8-030708-generic
 
 Do I miss something obvious? Or should I wait until next kernel version?

   You need to make a read-only snapshot with the -r option to btrfs
sub snap. This is independent of the mount options, and prevents the
resulting subvolume from being modified during the send operation.

   The error message isn't obvious, and should probably be improved.

   Hugo.

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