[Libguestfs] [PATCH 0/4] Allow shrinking of ext2, PVs and NTFS

[Richard W.M. Jones]

This patch series allows you to shrink various objects, as
requested in the following bugs:

https://bugzilla.redhat.com/show_bug.cgi?id=585221  # resize2fs
https://bugzilla.redhat.com/show_bug.cgi?id=585222  # pvresize
https://bugzilla.redhat.com/show_bug.cgi?id=585223  # ntfsresize

The first patch provides a consistent way to specify numbers
with suffixes to guestfish, eg:

  truncate-size /foo 1G

It also unifies the number parsing code used by 'alloc' and
'sparse' commands to use the same Gnulib function.

Patches 2-4 implement the resizing.

With all four patches applied you can shrink filesystems even where
the container is larger, and you can use suffixes to specify the new
filesystem size.

Example using resize2fs-size:

  $ guestfish -N fs:ext3:1G
  
  Welcome to guestfish, the libguestfs filesystem interactive shell for
  editing virtual machine filesystems.
  
  Type: 'help' for a list of commands
        'man' to read the manual
        'quit' to quit the shell
  
  ><fs> vfs-type /dev/vda1
  ext3
  ><fs> blockdev-getsize64 /dev/vda1
  1073741312
  ><fs> resize2fs-size /dev/vda1 100M
  ><fs> blockdev-getsize64 /dev/vda1    # container size same
  1073741312
  ><fs> mount-ro /dev/vda1 /            # but filesystem is smaller
  ><fs> df-h 
  Filesystem            Size  Used Avail Use% Mounted on
  /dev/vda1              98M   17M   77M  18% /sysroot

Example using pvresize-size:

  $ guestfish -N part:1G
  
  Welcome to guestfish, the libguestfs filesystem interactive shell for
  editing virtual machine filesystems.
  
  Type: 'help' for a list of commands
        'man' to read the manual
        'quit' to quit the shell
  
  ><fs> pvcreate /dev/vda1 
  ><fs> pvresize-size /dev/vda1 512M
  ><fs> pvs-full 
  [0] = {
[...]
    pv_size: 536870912
    dev_size: 1073741312
[...]
  }

Example using ntfsresize-size:

  $ guestfish -N fs:ntfs:1G
  
  Welcome to guestfish, the libguestfs filesystem interactive shell for
  editing virtual machine filesystems.
  
  Type: 'help' for a list of commands
        'man' to read the manual
        'quit' to quit the shell
  
  ><fs> ntfsresize-size /dev/vda1 512M
  ><fs> mount-ro /dev/vda1 /
  ><fs> df-h
  Filesystem            Size  Used Avail Use% Mounted on
  /dev/vda1             512M  5.6M  507M   2% /sysroot

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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