From b4cbca440070641199920a2d73a6abd95c9a9ec7 Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Tue, 2 Sep 2025 11:34:10 +0100 Subject: btrfs: don't allow adding block device of less than 1 MB From: Mark Harmstone [ Upstream commit 3d1267475b94b3df7a61e4ea6788c7c5d9e473c4 ] Commit 15ae0410c37a79 ("btrfs-progs: add error handling for device_get_partition_size_fd_stat()") in btrfs-progs inadvertently changed it so that if the BLKGETSIZE64 ioctl on a block device returned a size of 0, this was no longer seen as an error condition. Unfortunately this is how disconnected NBD devices behave, meaning that with btrfs-progs 6.16 it's now possible to add a device you can't remove: # btrfs device add /dev/nbd0 /root/temp # btrfs device remove /dev/nbd0 /root/temp ERROR: error removing device '/dev/nbd0': Invalid argument This check should always have been done kernel-side anyway, so add a check in btrfs_init_new_device() that the new device doesn't have a size less than BTRFS_DEVICE_RANGE_RESERVED (i.e. 1 MB). Reviewed-by: Qu Wenruo Signed-off-by: Mark Harmstone Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/volumes.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index f475b4b7c4578..817d3ef501ec4 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -2714,6 +2714,11 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path goto error; } + if (bdev_nr_bytes(file_bdev(bdev_file)) <= BTRFS_DEVICE_RANGE_RESERVED) { + ret = -EINVAL; + goto error; + } + if (fs_devices->seeding) { seeding_dev = true; down_write(&sb->s_umount); -- 2.51.0