Btrfs progs pre-release 5.15.1-rc1

Btrfs progs pre-release 5.15.1-rc1

[David Sterba]

Hi,

this is a pre-release announcement of btrfs-progs, 5.15.1-rc1. There are fixes
and documentation updates.

The proper release is scheduled to this Friday, +1 day (2021-11-19).

There is no -rc1 tag and no tarball, the changes are in git branch v5.15.x in
the devel repositories.

Changelog:

* fixes:
  * fi usage: fix wrongly reported space of used or unallocated space
  * fix detection of block device discard capability
* check: add more sanity checks for checksum items
* build: make sphinx optional backend for documentation

Shortlog:

David Sterba (7):
      btrfs-progs: docs: add Glossary from wiki
      btrfs-progs: docs: RST formatting fixups
      btrfs-progs: docs: fix RST mkfs.btrfs table formatting
      btrfs-progs: docs: disable RST smartquotes for em-dash
      btrfs-progs: docs: integrate sphinx build
      btrfs-progs: docs: mention ntfs2btrfs conversion tool
      btrfs-progs: update CHANGES for 5.15.1

Mark Harmstone (1):
      btrfs-progs: check: add check for too many csum entries

Nikolay Borisov (2):
      btrfs-progs: fi usage: don't reset ratio to 1 if we don't have RAID56 profile
      btrfs-progs: fi usage: fix calculation of chunk size for RAID1/DUP profiles

Qu Wenruo (1):
      btrfs-progs: raid56: fix the wrong recovery condition for data and P case

Wang Yugui (1):
      btrfs-progs: fix discard support check