Re: [PATCH RFC v3 for-6.8/block 11/17] erofs: use bdev api

Yu Kuai
2024-01-04T12:32:50Z

Hi, Jan!

在 2024/01/04 20:02, Jan Kara 写道:
> On Thu 21-12-23 16:58:26, Yu Kuai wrote:
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> Avoid to access bd_inode directly, prepare to remove bd_inode from
>> block_device.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>
> I'm not erofs maintainer but IMO this is quite ugly and grows erofs_buf
> unnecessarily. I'd rather store 'sb' pointer in erofs_buf and then do the
> right thing in erofs_bread() which is the only place that seems to care
> about the erofs_is_fscache_mode() distinction... Also blkszbits is then
> trivially sb->s_blocksize_bits so it would all seem much more
> straightforward.

Thanks for your suggestion, I'll follow this unless Gao Xiang has other
suggestions.

Kuai
>
> Honza
>
>> ---
>> 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..bbe2fe199bf3 100644
>> --- a/fs/erofs/data.c
>> +++ b/fs/erofs/data.c
>> @@ -32,8 +32,8 @@ 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;
>> + u8 blkszbits = buf->inode ? buf->inode->i_blkbits : buf->blkszbits;
>> + erofs_off_t offset = (erofs_off_t)blkaddr << blkszbits;
>> pgoff_t index = offset >> PAGE_SHIFT;
>> struct page *page = buf->page;
>> struct folio *folio;
>> @@ -43,7 +43,9 @@ 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 +69,14 @@ 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;
>> + } 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 })
>> --
>> 2.39.2
>>