diff options
| author | Anand Jain <anand.jain@oracle.com> | 2023-09-28 09:09:47 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2023-10-12 16:44:17 +0200 |
| commit | a5b8a5f9f8355d27a4f8d0afa93427f16d2f3c1e (patch) | |
| tree | 4ac85151c5daf9050cd0d682e7c8518d2ddc4c3c /fs/btrfs/disk-io.c | |
| parent | 69d427f34ca0970c2280cccd64e24aa62ff7904a (diff) | |
btrfs: support cloned-device mount capability
Guilherme's previous work [1] aimed at the mounting of cloned devices
using a superblock flag SINGLE_DEV during mkfs.
[1] https://lore.kernel.org/linux-btrfs/20230831001544.3379273-1-gpiccoli@igalia.com/
Building upon this work, here is in memory only approach. As it mounts
we determine if the same fsid is already mounted if then we generate a
random temp fsid which shall be used the mount, in memory only not
written to the disk. We distinguish devices by devt.
Example:
$ fallocate -l 300m ./disk1.img
$ mkfs.btrfs -f ./disk1.img
$ cp ./disk1.img ./disk2.img
$ cp ./disk1.img ./disk3.img
$ mount -o loop ./disk1.img /btrfs
$ mount -o ./disk2.img /btrfs1
$ mount -o ./disk3.img /btrfs2
$ btrfs fi show -m
Label: none uuid: 4a212b48-1bec-46a5-938a-783c8c1f0b02
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop0
Label: none uuid: adabf2fe-5515-4ad0-95b4-7b1609218c16
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop1
Label: none uuid: 1d77d0df-7d92-439e-adbd-20b9b86fdedb
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop2
Co-developed-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/disk-io.c')
| -rw-r--r-- | fs/btrfs/disk-io.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 178312c2efc8..ff3802986b3e 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2399,7 +2399,8 @@ int btrfs_validate_super(struct btrfs_fs_info *fs_info, ret = -EINVAL; } - if (memcmp(fs_info->fs_devices->fsid, sb->fsid, BTRFS_FSID_SIZE) != 0) { + if (!fs_info->fs_devices->temp_fsid && + memcmp(fs_info->fs_devices->fsid, sb->fsid, BTRFS_FSID_SIZE) != 0) { btrfs_err(fs_info, "superblock fsid doesn't match fsid of fs_devices: %pU != %pU", sb->fsid, fs_info->fs_devices->fsid); |