Re: [PATCH] f2fs: compress: remove unneed check condition

[Chao Yu]

On 2021/4/22 12:04, Jaegeuk Kim wrote:
> On 04/21, Chao Yu wrote:
> > In only call path of __cluster_may_compress(), __f2fs_write_data_pages()
> > has checked SBI_POR_DOING condition, and also cluster_may_compress()
> > has checked CP_ERROR_FLAG condition, so remove redundant check condition
> > in __cluster_may_compress() for cleanup.
>
> I think cp_error can get any time without synchronization. Is it safe to say
> it's redundant?

Yes,

But no matter how late we check cp_error, cp_error can happen after our
check points, it won't cause regression if we remove cp_error check there,
because for compress write, it uses OPU, it won't overwrite any existed data
in device.

Seems it will be more appropriate to check cp_error in
f2fs_write_compressed_pages() like we did in f2fs_write_single_data_page()
rather than in __cluster_may_compress().

BTW, shouldn't we rename __cluster_may_compress() to
cluster_beyond_filesize() for better readability?

Thanks,

> > Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
> > ---
> >   fs/f2fs/compress.c | 5 -----
> >   1 file changed, 5 deletions(-)
> >
> > diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> > index 3c9d797dbdd6..532c311e3a89 100644
> > --- a/fs/f2fs/compress.c
> > +++ b/fs/f2fs/compress.c
> > @@ -906,11 +906,6 @@ static bool __cluster_may_compress(struct compress_ctx *cc)
> >   
> >   		f2fs_bug_on(sbi, !page);
> >   
> > -		if (unlikely(f2fs_cp_error(sbi)))
> > -			return false;
> > -		if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
> > -			return false;
> > -
> >   		/* beyond EOF */
> >   		if (page->index >= nr_pages)
> >   			return false;
> > --
> > 2.29.2
> .