[PATCH 0/5] mkfs: Configuration file defined options

Dave Chinner
2020-10-15T03:29:35Z

Version 2:

- "-c file=xxx" > "-c options=xxx"
- split out constification into new patch
- removed debug output
- fixed some comments
- added man page stuff

Hi Folks,

Because needing config files for mkfs came up yet again in
discussion, here is a simple implementation of INI format config
files. These config files behave identically to options specified on
the command line - the do not change defaults, they do not override
CLI options, they are not overridden by cli options.

Example:

$ echo -e "[metadata]\ncrc = 0" > foo
$ mkfs/mkfs.xfs -N -c options=foo -d file=1,size=100m blah
Parameters parsed from config file foo successfully
meta-data=blah isize=256 agcount=4, agsize=6400 blks
= sectsz=512 attr=2, projid32bit=1
= crc=0 finobt=0, sparse=0, rmapbt=0
= reflink=0
data = bsize=4096 blocks=25600, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=853, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
$

And there's a V4 filesystem as specified by the option defined
in the config file. If we do:

$ mkfs/mkfs.xfs -N -c options=foo -m crc=1 -d file=1,size=100m blah
-m crc option respecified
Usage: mkfs.xfs
.....
$

You can see it errors out because the CRC option was specified in
both the config file and on the CLI.

There's lots of stuff we can do to make the conflict and respec
error messages better, but that doesn't change the basic
functionality of config file based mkfs options. To allow for future
changes to the way we want to apply config files, I created a
full option subtype for config files. That means we can add another
option to say "apply config file as default values rather than as
options" if we decide that is functionality that we want to support.

However, policy decisions like that are completely separate to the
mechanism, so these patches don't try to address desires to ship
"tuned" configs, system wide option files, shipping distro specific
defaults in config files, etc. This is purely a mechanism to allow
users to specify options via files instead of on the CLI. No more,
no less.

This has only been given a basic smoke testing right now (see above!
:). I need to get Darrick's tests from the previous round of config
file bikeshedding working in my test environment to do more
substantial testing of this....

Cheers,

Dave.

Dave Chinner (5):
build: add support for libinih for mkfs
mkfs: add initial ini format config file parsing support
mkfs: constify various strings
mkfs: hook up suboption parsing to ini files
mkfs: document config files in mkfs.xfs(8)

configure.ac | 3 +
doc/INSTALL | 5 +
include/builddefs.in | 1 +
include/linux.h | 2 +-
m4/package_inih.m4 | 20 ++++
man/man8/mkfs.xfs.8 | 113 +++++++++++++++++++--
mkfs/Makefile | 2 +-
mkfs/xfs_mkfs.c | 228 ++++++++++++++++++++++++++++++++++++++-----
8 files changed, 340 insertions(+), 34 deletions(-)
create mode 100644 m4/package_inih.m4

--
2.28.0