Date:   Tue, 11 Jan 2022 10:55:31 -0800
From:   Roman Gushchin <guro@fb.com>
To:     Muchun Song <songmuchun@bytedance.com>
CC:     <willy@infradead.org>, <akpm@linux-foundation.org>,
        <hannes@cmpxchg.org>, <mhocko@kernel.org>,
        <vdavydov.dev@gmail.com>, <shakeelb@google.com>,
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        <trond.myklebust@hammerspace.com>, <anna.schumaker@netapp.com>,
        <jaegeuk@kernel.org>, <chao@kernel.org>,
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        <duanxiongchun@bytedance.com>, <fam.zheng@bytedance.com>,
        <smuchun@gmail.com>
Subject: Re: [PATCH v5 03/16] fs: introduce alloc_inode_sb() to allocate
 filesystems specific inode
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References: <20211220085649.8196-1-songmuchun@bytedance.com>
 <20211220085649.8196-4-songmuchun@bytedance.com>
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On Mon, Dec 20, 2021 at 04:56:36PM +0800, Muchun Song wrote:
> The allocated inode cache is supposed to be added to its memcg list_lru
> which should be allocated as well in advance. That can be done by
> kmem_cache_alloc_lru() which allocates object and list_lru. The file
> systems is main user of it. So introduce alloc_inode_sb() to allocate
> file system specific inodes and set up the inode reclaim context
> properly. The file system is supposed to use alloc_inode_sb() to
> allocate inodes. In the later patches, we will convert all users to the
> new API.
> 
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
>  Documentation/filesystems/porting.rst |  5 +++++
>  fs/inode.c                            |  2 +-
>  include/linux/fs.h                    | 11 +++++++++++
>  3 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
> index bf19fd6b86e7..c9c157d7b7bb 100644
> --- a/Documentation/filesystems/porting.rst
> +++ b/Documentation/filesystems/porting.rst
> @@ -45,6 +45,11 @@ typically between calling iget_locked() and unlocking the inode.
>  
>  At some point that will become mandatory.
>  
> +**mandatory**
> +
> +The foo_inode_info should always be allocated through alloc_inode_sb() rather
> +than kmem_cache_alloc() or kmalloc() related.

I'd add a couple of words on why it has to be allocated this way.
> +
>  ---

Reviewed-by: Roman Gushchin <guro@fb.com>

Thanks!