Re: [f2fs-dev] [PATCH 4/5] f2fs: get rid of stale fault injection code

[Jaegeuk Kim]

On 04/11, Chao Yu wrote:
> On 2022/4/6 11:01, Yufen Yu via Linux-f2fs-devel wrote:
> > Hi,
> > 
> > On 2022/4/1 16:28, Chao Yu wrote:
> > > On 2022/4/1 15:19, Yufen Yu via Linux-f2fs-devel wrote:
> > > > Nowly, we can use new fault injection framework. Just delete the
> > > > stale fault injection code.
> > > > 
> > > > Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
> > > > ---
> > > >   fs/f2fs/checkpoint.c |  2 +-
> > > >   fs/f2fs/f2fs.h       | 51 ++----------------------------------------
> > > >   fs/f2fs/super.c      | 53 --------------------------------------------
> > > >   fs/f2fs/sysfs.c      | 23 -------------------
> > > >   4 files changed, 3 insertions(+), 126 deletions(-)
> > > > 
> > 
> > ...
> > 
> > > >               break;
> > > > @@ -1963,14 +1920,6 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> > > >       if (F2FS_IO_SIZE_BITS(sbi))
> > > >           seq_printf(seq, ",io_bits=%u",
> > > >                   F2FS_OPTION(sbi).write_io_size_bits);
> > > > -#ifdef CONFIG_F2FS_FAULT_INJECTION
> > > > -    if (test_opt(sbi, FAULT_INJECTION)) {
> > > > -        seq_printf(seq, ",fault_injection=%u",
> > > > -                F2FS_OPTION(sbi).fault_info.inject_rate);
> > > > -        seq_printf(seq, ",fault_type=%u",
> > > > -                F2FS_OPTION(sbi).fault_info.inject_type);
> > > > -    }
> > > > -#endif
> > > 
> > > This will cause regression due to it breaks application usage w/ -o
> > > fault_* mountoption..., I don't think this is the right way.
> > 
> > 
> > Thanks for catching this. I admit it's a problem. But, IMO fault_* mount
> > option are mostly been used in test, not in actual product. So, I think
> > it may just affect some test applications. With the common fault injection
> > framework, it can be more easy and flexible to do fault injection test.
> > Therefore, I want to remove the two mount options directly.
> > 
> > If you really worried about compatibility, how about just reserving the
> > two inject_* options but without doing any thing for them. We actually
> > configure fault injections by debugfs in this patch.
> > 
> > Or do you have more better suggestion?
> 
> Could you please consider to keep original logic of f2fs fault injection
> if user use inject_* options, otherwise following common fault injection
> framework?
> 
> Thoughts?

I think it'd be useful to test roll-forward recovery flow by using those mount
options, since runtime fault injection cannot enable it during mount.

BTW, what is the real benefit to use the fault injection framework?

> 
> Thanks,
> 
> > 
> > Thanks,
> > Yufen
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
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