Re: [PATCH RFC v2 for-6.8/block 11/18] erofs: use bdev api

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

Hi,

在 2023/12/12 14:35, Gao Xiang 写道:
> On 2023/12/11 22:07, Yu Kuai wrote:
> > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> >
> > Avoid to access bd_inode directly, prepare to remove bd_inode from
> > block_devcie.
> >
> > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> > ---
> >   fs/erofs/data.c     | 18 ++++++++++++------
> >   fs/erofs/internal.h |  2 ++
> >   2 files changed, 14 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> > index c98aeda8abb2..8cf3618190ab 100644
> > --- a/fs/erofs/data.c
> > +++ b/fs/erofs/data.c
> > @@ -32,8 +32,7 @@ void erofs_put_metabuf(struct erofs_buf *buf)
> >   void *erofs_bread(struct erofs_buf *buf, erofs_blk_t blkaddr,
> >             enum erofs_kmap_type type)
> >   {
> > -    struct inode *inode = buf->inode;
> > -    erofs_off_t offset = (erofs_off_t)blkaddr << inode->i_blkbits;
> > +    erofs_off_t offset = (erofs_off_t)blkaddr << buf->blkszbits;
> I'd suggest that use `buf->blkszbits` only for bdev_read_folio() since
> erofs_init_metabuf() is not always called before erofs_bread() is used.
>
> For example, buf->inode can be one of directory inodes other than
> initialized by erofs_init_metabuf().

Thanks for the notice, and you're right, I'll update code in v3:

u8 blkszbits = buf->inode ? inode->i_blkbits : buf->blkszbits;
erofs_off_t offset = (erofs_off_t)blkaddr << blkszbits;

Kuai
> Thanks,
> Gao Xiang
>
>
> >       pgoff_t index = offset >> PAGE_SHIFT;
> >       struct page *page = buf->page;
> >       struct folio *folio;
> > @@ -43,7 +42,9 @@ void *erofs_bread(struct erofs_buf *buf, erofs_blk_t 
> > blkaddr,
> >           erofs_put_metabuf(buf);
> >           nofs_flag = memalloc_nofs_save();
> > -        folio = read_cache_folio(inode->i_mapping, index, NULL, NULL);
> > +        folio = buf->inode ?
> > +            read_mapping_folio(buf->inode->i_mapping, index, NULL) :
> > +            bdev_read_folio(buf->bdev, offset);
> >           memalloc_nofs_restore(nofs_flag);
> >           if (IS_ERR(folio))
> >               return folio;
> > @@ -67,10 +68,15 @@ void *erofs_bread(struct erofs_buf *buf, 
> > erofs_blk_t blkaddr,
> >   void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb)
> >   {
> > -    if (erofs_is_fscache_mode(sb))
> > +    if (erofs_is_fscache_mode(sb)) {
> >           buf->inode = EROFS_SB(sb)->s_fscache->inode;
> > -    else
> > -        buf->inode = sb->s_bdev->bd_inode;
> > +        buf->bdev = NULL;
> > +        buf->blkszbits = buf->inode->i_blkbits;
> > +    } else {
> > +        buf->inode = NULL;
> > +        buf->bdev = sb->s_bdev;
> > +        buf->blkszbits = EROFS_SB(sb)->blkszbits;
> > +    }
> >   }
> >   void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
> > diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> > index b0409badb017..c9206351b485 100644
> > --- a/fs/erofs/internal.h
> > +++ b/fs/erofs/internal.h
> > @@ -224,8 +224,10 @@ enum erofs_kmap_type {
> >   struct erofs_buf {
> >       struct inode *inode;
> > +    struct block_device *bdev;
> >       struct page *page;
> >       void *base;
> > +    u8 blkszbits;
> >       enum erofs_kmap_type kmap_type;
> >   };
> >   #define __EROFS_BUF_INITIALIZER    ((struct erofs_buf){ .page = NULL })
> .