btrfs: skip devices without magic signature when mounting (96c2e067) · Commits · 戴 / test

Many things can happen after the device is scanned and before the device is mounted. One such thing is losing the BTRFS_MAGIC on the device. If it happens we still won't free that device from the memory and cause the userland confusion. For example: As the BTRFS_IOC_DEV_INFO still carries the device path which does not have the BTRFS_MAGIC, 'btrfs fi show' still lists device which does not belong to the filesystem anymore: $ mkfs.btrfs -fq -draid1 -mraid1 /dev/sda /dev/sdb $ wipefs -a /dev/sdb # /dev/sdb does not contain magic signature $ mount -o degraded /dev/sda /btrfs $ btrfs fi show -m Label: none uuid: 470ec6fb-646b-4464-b3cb-df1b26c527bd Total devices 2 FS bytes used 128.00KiB devid 1 size 3.00GiB used 571.19MiB path /dev/sda devid 2 size 3.00GiB used 571.19MiB path /dev/sdb We need to distinguish the missing signature and invalid superblock, so add a specific error code ENODATA for that. This also fixes failure of fstest btrfs/198. CC: stable@vger.kernel.org # 4.19+ Reviewed-by:

Josef Bacik <josef@toxicpanda.com> Signed-off-by:

Anand Jain <anand.jain@oracle.com> Reviewed-by:

David Sterba <dsterba@suse.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -3424,8 +3424,12 @@ struct btrfs_super_block btrfs_read_dev_one_super(struct block_device bdev,
		return ERR_CAST(page);

		super = page_address(page);
		if (btrfs_super_bytenr(super) != bytenr \|\|
		btrfs_super_magic(super) != BTRFS_MAGIC) {
		if (btrfs_super_magic(super) != BTRFS_MAGIC) {
		btrfs_release_disk_super(super);
		return ERR_PTR(-ENODATA);
		}

		if (btrfs_super_bytenr(super) != bytenr) {
		btrfs_release_disk_super(super);
		return ERR_PTR(-EINVAL);
		}

fs/btrfs/volumes.c

+12 −6

Original line number	Diff line number	Diff line
		@@ -1198,17 +1198,23 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
		{
		struct btrfs_device *device;
		struct btrfs_device *latest_dev = NULL;
		struct btrfs_device *tmp_device;

		flags \|= FMODE_EXCL;

		list_for_each_entry(device, &fs_devices->devices, dev_list) {
		/* Just open everything we can; ignore failures here */
		if (btrfs_open_one_device(fs_devices, device, flags, holder))
		continue;
		list_for_each_entry_safe(device, tmp_device, &fs_devices->devices,
		dev_list) {
		int ret;

		if (!latest_dev \|\|
		device->generation > latest_dev->generation)
		ret = btrfs_open_one_device(fs_devices, device, flags, holder);
		if (ret == 0 &&
		(!latest_dev \|\| device->generation > latest_dev->generation)) {
		latest_dev = device;
		} else if (ret == -ENODATA) {
		fs_devices->num_devices--;
		list_del(&device->dev_list);
		btrfs_free_device(device);
		}
		}
		if (fs_devices->open_devices == 0)
		return -EINVAL;

Admin message