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Commit b772a86e authored by Li Zefan's avatar Li Zefan Committed by David Sterba
Browse files

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: default avatarLi Zefan <lizf@cn.fujitsu.com>
parent ece7d20e

fs/btrfs/super.c

+3 −3
Original line number Diff line number Diff line
@@ -1083,7 +1083,7 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes) 
	int i = 0, nr_devices;

	int ret;



	nr_devices = fs_info->fs_devices->rw_devices;

	nr_devices = fs_info->fs_devices->open_devices;

	BUG_ON(!nr_devices);



	devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
@@ -1105,8 +1105,8 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes) 
	else

		min_stripe_size = BTRFS_STRIPE_LEN;



	list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {

		if (!device->in_fs_metadata)

	list_for_each_entry(device, &fs_devices->devices, dev_list) {

		if (!device->in_fs_metadata || !device->bdev)

			continue;



		avail_space = device->total_bytes - device->bytes_used;