Re: [PATCH 00/42] mkfs: factor the crap out of the code

[Chandan Rajendra <chandan@linux.vnet.ibm.com>]

On Wednesday, August 30, 2017 5:20:10 AM IST Dave Chinner wrote:
> Everyone who tries to modify mkfs quickly learns that it is a pile
> of spaghetti, the only difference in opinion is whether it is a
> steaming, cold or rotten pile. This patchset attempts to untangle
> the ball of pasta and turn it into a set of clear, obvious
> operations that lead to a filesystem being formatted correctly.
> 
> The patch series is really in three parts, splitting the code up
> into roughly three modules. The first part introduces a mkfs
> parameters structure and factors the on-disk formatting code to use
> only information in that structure. The second part introduces a
> command line input structure and factors the input parsing to use
> it. This requires a bunch of temporary code to keep the rest of
> the code working. The third part is factoring the input validation
> and geometry calculation code to use the input structure and put
> the output into the mkfs parameter structure and to remove all the
> temporary support code.
> 
> The result is three modules - input parsing, validation+calculations
> and formatting - with well defined data flow between them. This also
> paves the way to supporting config files to set defaults via a
> separate (new) module. The overall data flow now looks like this:
> 
> Build defaults --\
>                   ---> mkfs_default_params -> CLI -> mkfs_params
> config file -----/
> 
> It is not worth spending a lot of time reviewing the temporary code
> that is added - it gets removed before the end of the series. No
> attempt has been made to ensure that mkfs works 100% correctly after
> each patch is applied - the only guarantee is that it will build
> cleanly. It /should/ work if a bisect lands in the middle of the
> series, but trying to exhaustively test each patch is OK would take
> more effort than it is worth. As such, testing has only been
> performed on the whole series.
> 
> The new output from mkfs to indicate where it has sourced the
> defaults from causes xfstests to have conniptions. This requires
> some updates to the mkfs output filters that are already in place
> but it is a fairly trivial update. Test xfs/191 has a couple of new
> failures, but that is because the new code now correctly parses
> things like agsize so that block and sector size based
> specifications work with default mkfs values. This will require test
> updates.
> 
> Future work will be to split the xfs_mkfs.c file into a file per
> module (i.e. seperate files for CLI parsing, mkfs formating,
> validation+calculation and, finally, one for config file support),
> but otherwise the majority of the factoring work is now complete.
> 
> Comments, flames, etc all welcome.
Hi Dave,

I am trying to test the "mkfs refactor" patchset on a ppc64 machine. But "git
am ~/mkfs-xfs-rewrite/\[PATCH\ 03_42\]\ mkfs_introduce\ a\ structure\ to\
hold\ CLI\ options.mbox" fails to apply cleanly on top of xfsprogs/master
(with patches 01 and 02 already applied) branch. Can you please let me know
the id of the topmost commit on which the "mkfs refactor" patches are applied? 

-- 
chandan