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Date:   Thu, 7 Apr 2022 22:09:50 +0800
From:   Gao Xiang <xiang@kernel.org>
To:     Jeffle Xu <jefflexu@linux.alibaba.com>
Cc:     dhowells@redhat.com, linux-cachefs@redhat.com, xiang@kernel.org,
        chao@kernel.org, linux-erofs@lists.ozlabs.org,
        torvalds@linux-foundation.org, gregkh@linuxfoundation.org,
        willy@infradead.org, linux-fsdevel@vger.kernel.org,
        joseph.qi@linux.alibaba.com, bo.liu@linux.alibaba.com,
        tao.peng@linux.alibaba.com, gerry@linux.alibaba.com,
        eguan@linux.alibaba.com, linux-kernel@vger.kernel.org,
        luodaowen.backend@bytedance.com, tianzichen@kuaishou.com,
        fannaihao@baidu.com
Subject: Re: [PATCH v8 14/20] erofs: register fscache context for primary
 data blob
Message-ID: <Yk7wrmKYHbhJM8CY@debian>
Mail-Followup-To: Jeffle Xu <jefflexu@linux.alibaba.com>,
        dhowells@redhat.com, linux-cachefs@redhat.com, xiang@kernel.org,
        chao@kernel.org, linux-erofs@lists.ozlabs.org,
        torvalds@linux-foundation.org, gregkh@linuxfoundation.org,
        willy@infradead.org, linux-fsdevel@vger.kernel.org,
        joseph.qi@linux.alibaba.com, bo.liu@linux.alibaba.com,
        tao.peng@linux.alibaba.com, gerry@linux.alibaba.com,
        eguan@linux.alibaba.com, linux-kernel@vger.kernel.org,
        luodaowen.backend@bytedance.com, tianzichen@kuaishou.com,
        fannaihao@baidu.com
References: <20220406075612.60298-1-jefflexu@linux.alibaba.com>
 <20220406075612.60298-15-jefflexu@linux.alibaba.com>
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On Wed, Apr 06, 2022 at 03:56:06PM +0800, Jeffle Xu wrote:
> Registers fscache context for primary data blob. Also move the
> initialization of s_op and related fields forward, since anonymous
> inode will be allocated under the super block when registering the
> fscache context.
> 
> Something worth mentioning about the cleanup routine.
> 
> 1. The fscache context will instantiate anonymous inodes under the super
> block. Release these anonymous inodes when .put_super() is called, or
> we'll get "VFS: Busy inodes after unmount." warning.
> 
> 2. The fscache context is initialized prior to the root inode. If
> .kill_sb() is called when mount failed, .put_super() won't be called
> when root inode has not been initialized yet. Thus .kill_sb() shall
> also contain the cleanup routine.
> 
> Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>

Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Thanks,
Gao Xiang

> ---
>  fs/erofs/internal.h |  1 +
>  fs/erofs/super.c    | 15 +++++++++++----
>  2 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 3a4a344cfed3..eb37b33bce37 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -155,6 +155,7 @@ struct erofs_sb_info {
>  
>  	/* fscache support */
>  	struct fscache_volume *volume;
> +	struct erofs_fscache *s_fscache;
>  };
>  
>  #define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 6590ed1b7d3b..9498b899b73b 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -585,6 +585,9 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>  	int err;
>  
>  	sb->s_magic = EROFS_SUPER_MAGIC;
> +	sb->s_flags |= SB_RDONLY | SB_NOATIME;
> +	sb->s_maxbytes = MAX_LFS_FILESIZE;
> +	sb->s_op = &erofs_sops;
>  
>  	if (!sb_set_blocksize(sb, EROFS_BLKSIZ)) {
>  		erofs_err(sb, "failed to set erofs blksize");
> @@ -605,6 +608,11 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>  		err = erofs_fscache_register_fs(sb);
>  		if (err)
>  			return err;
> +
> +		err = erofs_fscache_register_cookie(sb, &sbi->s_fscache,
> +						    sbi->opt.fsid, true);
> +		if (err)
> +			return err;
>  	}
>  
>  	err = erofs_read_superblock(sb);
> @@ -619,11 +627,8 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>  			clear_opt(&sbi->opt, DAX_ALWAYS);
>  		}
>  	}
> -	sb->s_flags |= SB_RDONLY | SB_NOATIME;
> -	sb->s_maxbytes = MAX_LFS_FILESIZE;
> -	sb->s_time_gran = 1;
>  
> -	sb->s_op = &erofs_sops;
> +	sb->s_time_gran = 1;
>  	sb->s_xattr = erofs_xattr_handlers;
>  
>  	if (test_opt(&sbi->opt, POSIX_ACL))
> @@ -763,6 +768,7 @@ static void erofs_kill_sb(struct super_block *sb)
>  
>  	erofs_free_dev_context(sbi->devs);
>  	fs_put_dax(sbi->dax_dev);
> +	erofs_fscache_unregister_cookie(&sbi->s_fscache);
>  	erofs_fscache_unregister_fs(sb);
>  	kfree(sbi);
>  	sb->s_fs_info = NULL;
> @@ -781,6 +787,7 @@ static void erofs_put_super(struct super_block *sb)
>  	iput(sbi->managed_cache);
>  	sbi->managed_cache = NULL;
>  #endif
> +	erofs_fscache_unregister_cookie(&sbi->s_fscache);
>  }
>  
>  static struct file_system_type erofs_fs_type = {
> -- 
> 2.27.0
>