The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 96c2e067ed3e3e004580a643c76f58729206b829 Mon Sep 17 00:00:00 2001
From: Anand Jain anand.jain@oracle.com Date: Wed, 30 Sep 2020 21:09:52 +0800 Subject: [PATCH] btrfs: skip devices without magic signature when mounting
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
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3d39f5d47ad3..764001609a15 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -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); } diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 46f4efd58652..58b9c419a2b6 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -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;