Re: [PATCH 03/15] md: use folio for bb_folio

[Li Nan]

在 2026/1/19 11:03, Xiao Ni 写道:
> On Wed, Dec 17, 2025 at 8:11 PM <linan666@xxxxxxxxxxxxxxx> wrote:
> > From: Li Nan <linan122@xxxxxxxxxx>
> >
> > Convert bio_page to bio_folio and use it throughout.
> >
> > Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
> > ---
> >   drivers/md/md.h |  3 ++-
> >   drivers/md/md.c | 25 +++++++++++++------------
> >   2 files changed, 15 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/md/md.h b/drivers/md/md.h
> > index 410f8a6b75e7..aa6d9df50fd0 100644
> > --- a/drivers/md/md.h
> > +++ b/drivers/md/md.h
> > @@ -144,7 +144,8 @@ struct md_rdev {
> >          struct block_device *bdev;      /* block device handle */
> >          struct file *bdev_file;         /* Handle from open for bdev */
> >
> > -       struct page     *sb_page, *bb_page;
> > +       struct page     *sb_page;
> > +       struct folio    *bb_folio;
> >          int             sb_loaded;
> >          __u64           sb_events;
> >          sector_t        data_offset;    /* start of data in array */
> > diff --git a/drivers/md/md.c b/drivers/md/md.c
> > index 9dfd6f8da5b8..0732bbcdb95d 100644
> > --- a/drivers/md/md.c
> > +++ b/drivers/md/md.c
> > @@ -1073,9 +1073,9 @@ void md_rdev_clear(struct md_rdev *rdev)
> >                  rdev->sb_start = 0;
> >                  rdev->sectors = 0;
> >          }
> > -       if (rdev->bb_page) {
> > -               put_page(rdev->bb_page);
> > -               rdev->bb_page = NULL;
> > +       if (rdev->bb_folio) {
> > +               folio_put(rdev->bb_folio);
> > +               rdev->bb_folio = NULL;
> >          }
> >          badblocks_exit(&rdev->badblocks);
> >   }
> > @@ -1909,9 +1909,10 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
> >
> >          rdev->desc_nr = le32_to_cpu(sb->dev_number);
> >
> > -       if (!rdev->bb_page) {
> > -               rdev->bb_page = alloc_page(GFP_KERNEL);
> > -               if (!rdev->bb_page)
> > +       if (!rdev->bb_folio) {
> > +               rdev->bb_folio = folio_alloc(GFP_KERNEL, 0);
> > +
> > +               if (!rdev->bb_folio)
> >                          return -ENOMEM;
> >          }
> >          if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BAD_BLOCKS) &&
> > @@ -1930,10 +1931,10 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
> >                  if (offset == 0)
> >                          return -EINVAL;
> >                  bb_sector = (long long)offset;
> > -               if (!sync_page_io(rdev, bb_sector, sectors << 9,
> > -                                 rdev->bb_page, REQ_OP_READ, true))
> > +               if (!sync_folio_io(rdev, bb_sector, sectors << 9, 0,
> > +                                 rdev->bb_folio, REQ_OP_READ, true))
> >                          return -EIO;
> > -               bbp = (__le64 *)page_address(rdev->bb_page);
> > +               bbp = (__le64 *)folio_address(rdev->bb_folio);
> >                  rdev->badblocks.shift = sb->bblog_shift;
> >                  for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) {
> >                          u64 bb = le64_to_cpu(*bbp);
> > @@ -2300,7 +2301,7 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
> >                  md_error(mddev, rdev);
> >          else {
> >                  struct badblocks *bb = &rdev->badblocks;
> > -               __le64 *bbp = (__le64 *)page_address(rdev->bb_page);
> > +               __le64 *bbp = (__le64 *)folio_address(rdev->bb_folio);
> >                  u64 *p = bb->page;
> >                  sb->feature_map |= cpu_to_le32(MD_FEATURE_BAD_BLOCKS);
> >                  if (bb->changed) {
> > @@ -2953,7 +2954,7 @@ void md_update_sb(struct mddev *mddev, int force_change)
> >                                  md_write_metadata(mddev, rdev,
> >                                                    rdev->badblocks.sector,
> >                                                    rdev->badblocks.size << 9,
> > -                                                 rdev->bb_page, 0);
> > +                                                 folio_page(rdev->bb_folio, 0), 0);
> >                                  rdev->badblocks.size = 0;
> >                          }
> >
> > @@ -3809,7 +3810,7 @@ int md_rdev_init(struct md_rdev *rdev)
> >          rdev->sb_events = 0;
> >          rdev->last_read_error = 0;
> >          rdev->sb_loaded = 0;
> > -       rdev->bb_page = NULL;
> > +       rdev->bb_folio = NULL;
> >          atomic_set(&rdev->nr_pending, 0);
> >          atomic_set(&rdev->read_errors, 0);
> >          atomic_set(&rdev->corrected_errors, 0);
> > --
> > 2.39.2
>
> Hi Nan
>
> Bad block page is only one single page. I don't think it's necessary
> to use folio here. And it uses folio_page to get the page again. Or do
> you plan to replace all page apis to folio apis? Looking through all
> patches, sync_page_io is not removed. In patch02, it says sync_page_io
> will be removed. So maybe it's better to switch bb_page to bb_folio in
> your second patch set? And this patch set only focuses on replacing
> sync pages with folio. It's my 2 cents point. If you think it's better
> to change the bad block page here, I'm still ok.
>
> Best Regards
> Xiao

Hi Xiao,

Thanks for your review. Move it to next patch set is fine. I will delete
this patch in v2.

--
Thanks,
Nan