Btrfs: fix oops when calling statfs on readonly device
commitb772a86ea6d932ac29d5e50e67c977653c832f8a
authorLi Zefan <lizf@cn.fujitsu.com>
Mon, 28 Nov 2011 08:43:00 +0000 (28 16:43 +0800)
committerDavid Sterba <dsterba@suse.cz>
Wed, 30 Nov 2011 17:46:05 +0000 (30 18:46 +0100)
treec142daf34c910b496ce578dfb391a8ebd929652e
parentece7d20e8be6730fbb29f4550de6b19b1a3a9387
Btrfs: fix oops when calling statfs on readonly device

To reproduce this bug:

  # dd if=/dev/zero of=img bs=1M count=256
  # mkfs.btrfs img
  # losetup -r /dev/loop1 img
  # mount /dev/loop1 /mnt
  OOPS!!

It triggered BUG_ON(!nr_devices) in btrfs_calc_avail_data_space().

To fix this, instead of checking write-only devices, we check all open
deivces:

  # df -h /dev/loop1
  Filesystem            Size  Used Avail Use% Mounted on
  /dev/loop1            250M   28K  238M   1% /mnt

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
fs/btrfs/super.c