Btrfs progs release 3.18

[David Sterba <dsterba@suse.cz>]

Hi,

let me announce the release of btrfs-progs version 3.18. There are
updates to UI and several enhancements of check/repair. About 100
commits from 14 contributors, thank you all!

Tarballs: https://www.kernel.org/pub/linux/kernel/people/kdave/btrfs-progs/
Git: git://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git


Major user-visible changes:

* mkfs - skinny-metadata feature is now on by default, first introduced
  in kernel 3.10

New subcommands:

* filesystem usage - give an overview of fs usage in a way that's more
  comprehensible than existing 'fi df'
  * on kernels < 3.18: requires root due to restricted ioctl FS_INFO
  * raid 5/6 numbers may be missing due to restricte ioctl (TREE_SEARCH)
  * that's used to calculate the numbers
* device usage - more detailed information about per-device allocations
  * same restrictions as for 'fi usage'

New features, options:

* check
  * option to set a different tree root byte number
  * ability to link lost files to lost+found, caused by a recent
    kernel bug
  * repair of severely corrupted fs (use with care):
    * recover from corrupted b-tree
    * ability to rebuild inode items from other items
    * improved rebuilding of extent tree with snapshots
* convert
  * option to show progress
* subvol create - print the commit mode inline, print the global mode
  only if --verbose

Other updates:

* musl-libc build support
* bugfixes for coverity reports
* new test images, testing framework
* documentation