linux-ext4 - Re: [PATCH -next] ext4: use DEFINE_MUTEX (and mutex

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Message-ID: <X+P1IKbjELeomyeo@mit.edu>
Date:   Wed, 23 Dec 2020 20:55:44 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Zheng Yongjun <zhengyongjun3@...wei.com>
Cc:     adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] ext4: use DEFINE_MUTEX (and mutex_init() had been
 too late)

On Wed, Dec 23, 2020 at 10:12:54PM +0800, Zheng Yongjun wrote:
> Signed-off-by: Zheng Yongjun <zhengyongjun3@...wei.com>

Why is mutex_init() too late?  We only take the mutex after we
mounting an ext4 file system, and that can't happen until ext4_init_fs
is called.

					- Ted

>  fs/ext4/super.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 94472044f4c1..8776f06a639d 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -59,7 +59,7 @@
>  #include <trace/events/ext4.h>
>  
>  static struct ext4_lazy_init *ext4_li_info;
> -static struct mutex ext4_li_mtx;
> +static DEFINE_MUTEX(ext4_li_mtx);
>  static struct ratelimit_state ext4_mount_msg_ratelimit;
>  
>  static int ext4_load_journal(struct super_block *, struct ext4_super_block *,
> @@ -6640,7 +6640,6 @@ static int __init ext4_init_fs(void)
>  
>  	ratelimit_state_init(&ext4_mount_msg_ratelimit, 30 * HZ, 64);
>  	ext4_li_info = NULL;
> -	mutex_init(&ext4_li_mtx);
>  
>  	/* Build-time check for flags consistency */
>  	ext4_check_flag_values();
> -- 
> 2.22.0
>