Btrfs: fix oops when calling statfs on readonly device (b772a86e) · Commits · 戴 / test

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

+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;

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