btrfs-progs: add --default-subvol option to mkfs.btrfs

[maharmstone]

Adds a --default-subvol option to mkfs.btrfs, which works the same way as --subvol but also marks the subvolume as the default.

[maharmstone]

Fixed minor inelegance in btrfs_set_default_subvolume (no need to check return value at end of function)

[DaanDeMeyer]

mkfs.btrfs: unrecognized option '--default-subvol'
usage: mkfs.btrfs [options] <dev> [<dev...>]

    Create a BTRFS filesystem on a device or multiple devices

    Allocation profiles:
    -d|--data PROFILE         data profile, raid0, raid1, raid1c3, raid1c4, raid5, raid6, raid10, dup or single
    -m|--metadata PROFILE     metadata profile, values like for data profile 
    -M|--mixed                mix metadata and data together 
    Features:
    --csum TYPE               
    --checksum TYPE           checksum algorithm to use, crc32c (default), xxhash, sha256, blake2 
    -n|--nodesize SIZE        size of btree nodes 
    -s|--sectorsize SIZE      data block size (may not be mountable by current kernel) 
    -O|--features LIST        comma separated list of filesystem features (use '-O list-all' to list features) 
    -L|--label LABEL          set the filesystem label 
    -U|--uuid UUID            specify the filesystem UUID (must be unique for a filesystem with multiple devices)
    --device-uuid UUID        Specify the filesystem device UUID (a.k.a sub-uuid) (for single device filesystem
                              only) 
    Creation:
    -b|--byte-count SIZE      set size of each device to SIZE (filesystem size is sum of all device sizes) 
    -r|--rootdir DIR          copy files from DIR to the image root directory 
    -u|--subvol SUBDIR        create SUBDIR as subvolume rather than normal directory 
    -D|--default-subvol SUBDIR
                              create SUBDIR as subvolume rather than normal directory, and set it as the default 

[maharmstone]

mkfs.btrfs: unrecognized option '--default-subvol'
usage: mkfs.btrfs [options] <dev> [<dev...>]

    Create a BTRFS filesystem on a device or multiple devices

    Allocation profiles:
    -d|--data PROFILE         data profile, raid0, raid1, raid1c3, raid1c4, raid5, raid6, raid10, dup or single
    -m|--metadata PROFILE     metadata profile, values like for data profile 
    -M|--mixed                mix metadata and data together 
    Features:
    --csum TYPE               
    --checksum TYPE           checksum algorithm to use, crc32c (default), xxhash, sha256, blake2 
    -n|--nodesize SIZE        size of btree nodes 
    -s|--sectorsize SIZE      data block size (may not be mountable by current kernel) 
    -O|--features LIST        comma separated list of filesystem features (use '-O list-all' to list features) 
    -L|--label LABEL          set the filesystem label 
    -U|--uuid UUID            specify the filesystem UUID (must be unique for a filesystem with multiple devices)
    --device-uuid UUID        Specify the filesystem device UUID (a.k.a sub-uuid) (for single device filesystem
                              only) 
    Creation:
    -b|--byte-count SIZE      set size of each device to SIZE (filesystem size is sum of all device sizes) 
    -r|--rootdir DIR          copy files from DIR to the image root directory 
    -u|--subvol SUBDIR        create SUBDIR as subvolume rather than normal directory 
    -D|--default-subvol SUBDIR
                              create SUBDIR as subvolume rather than normal directory, and set it as the default 

Oops, I forgot to add the long form to the list. Sorry Daan, try it now

[DaanDeMeyer]

@adam900710 I am getting swarmed with hardlink warnings since your refactoring: https://paste.centos.org/view/a3a9b543. Any chance we can log this warning only for the first file instead of for every file?

[kdave]

I'll update so the warning is printed first time and after the whole directory is processed so it's not lost.

[adam900710]

@adam900710 I am getting swarmed with hardlink warnings since your refactoring: https://paste.centos.org/view/a3a9b543. Any chance we can log this warning only for the first file instead of for every file?

Unfortunately if it's only warned once, it will mask all the other files.

Another thing is, although the timezone ones are indeed hardlinks, the python ones in my system doesn't has any hardlink.
Not 100% sure if the split time zone files will cause anything wrong.

I'm afraid we may need to implement hard link support sooner than later.

[adam900710]

Overall looks good to me.

Just some small nitpicks.

[maharmstone]

Thanks Qu. I've force-pushed a version with your changes, and rebased it against 6.10.1.

[adam900710]

Looks good to me.

[kdave]

Merged to devel, thanks.

[maharmstone]

Thanks both