Re: man filesystems(5) doesn't contain Btrfs

[Andrei Borzenkov <arvidjaar@gmail.com>]

16.02.2017 23:47, Austin S. Hemmelgarn пишет:
> On 2017-02-16 15:36, Chris Murphy wrote:
>> Hi,
>>
>> This man page contains a list for pretty much every other file system,
>> with a oneliner description: ext4, XFS is in there, and even NTFS, but
>> not Btrfs.
>>
>> Also, /etc/filesystems doesn't contain Btrfs. Anyone know if either,
>> or both, ought to contain an entry for Btrfs?
>>
> The man-page absolutely should.  Ideally, that should be kept in sync
> with with the mount manpages, but I think they're in separate projects
> (mount is util-linux IIRC, while filesystems(5) is part of the Linux
> man-pages project).
> 
> As far as /etc/filesystems, that should be irrelevant.  Of the big
> distros, only SUSE, Fedora/CentOS/OEL, and Gentoo use it (I checked
> Arch, Gentoo, openSUSE, Fedora, Debian, and Ubuntu, which should cover
> at least 80% of users since this is low enough level derivatives won't
> be likely to change it), and all it does is dictate what order 'mount -t
> auto' will try filesystem types in.  All the distros that have it have a
> '*' on the last line, which means to check /proc/filesystems, and
> therefore will automatically try BTRFS if there's a kernel module for it
> (unless the module is blacklisted or prevented from being loaded on boot
> automatically).


Note that utils-linux does low-level device probe first and falls back
to reading /{etc,proc}/filesystems only if low level probing fails
(returns no recognized filesystem).