Re: [PATCH] f2fs: avoid unnecessary reads in f2fs_update_meta_block()

[Daeho Jeong]

On Sun, Oct 11, 2026 at 1:41 AM Chao Yu <chao@xxxxxxxxxx> wrote:
>
> On 10/2/26 14:48, Seongjae Jeong wrote:
> > When the packed SSA feature is enabled, f2fs_update_meta_block()
> > uses f2fs_get_meta_cache_retry(), which reads the target block from
> > disk if the cache entry is not uptodate.
> >
> > However, f2fs_update_meta_block() overwrites the entire filesystem
> > block with memcpy(), so the existing contents are not needed.
> > Partial updates to packed SSA blocks are handled separately in
> > write_sum_block().
> >
> > Use f2fs_grab_meta_cache() unconditionally to avoid reading blocks
> > that will be fully overwritten. Also remove the error check, since
> > f2fs_grab_meta_cache() retries allocation failures internally and
> > does not return an error pointer.
> >
> > Signed-off-by: Seongjae Jeong <jsjlee1020@xxxxxxxxx>
> > ---
> >   fs/f2fs/segment.c | 8 +-------
> >   1 file changed, 1 insertion(+), 7 deletions(-)
> >
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 794e0d99fc7c..51858f64e43e 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -2844,13 +2844,7 @@ void f2fs_update_meta_block(struct f2fs_sb_info *sbi,
> >   {
> >       struct f2fs_cached_block *entry;
> >
> > -     if (!f2fs_sb_has_packed_ssa(sbi))
> > -             entry = f2fs_grab_meta_cache(sbi, blk_addr);
> > -     else
> > -             entry = f2fs_get_meta_cache_retry(sbi, blk_addr);
> > -
> > -     if (IS_ERR(entry))
> > -             return;
> > +     entry = f2fs_grab_meta_cache(sbi, blk_addr);
>
> Daeho,
>
>  From code side, I feel this is clean.
>
> But, could you double check this cleanup? in case if we handle this
> intentionally in original patch for something.
>
> Thanks,

Looks good to me. Thanks~

>
> >
> >       memcpy(cache_address(entry), src, F2FS_BLKSIZE(sbi));
> >       f2fs_mark_cache_dirty(entry);
>