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

Gao Xiang
2023-12-12T06:35:59Z

On 2023/12/11 22:07, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
>
> Avoid to access bd_inode directly, prepare to remove bd_inode from
> block_devcie.
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
> 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,
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 })