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>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 8bd9d6d..1a3ce9e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1083,7 +1083,7 @@
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 @@
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;