linux-kernel - Re: [PATCH] zonefs: fix to update .i_wr_refcnt correctly in zonefs_open

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Message-ID: <BL0PR04MB65145B310933D52C432DA7BAE76B9@BL0PR04MB6514.namprd04.prod.outlook.com>
Date:   Tue, 16 Mar 2021 23:30:10 +0000
From:   Damien Le Moal <Damien.LeMoal@....com>
To:     Chao Yu <yuchao0@...wei.com>, Naohiro Aota <Naohiro.Aota@....com>,
        "jth@...nel.org" <jth@...nel.org>
CC:     "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "chao@...nel.org" <chao@...nel.org>
Subject: Re: [PATCH] zonefs: fix to update .i_wr_refcnt correctly in
 zonefs_open_zone()

On 2021/03/16 21:30, Chao Yu wrote:
> In zonefs_open_zone(), if opened zone count is larger than
> .s_max_open_zones threshold, we missed to recover .i_wr_refcnt,
> fix this.
> 
> Fixes: b5c00e975779 ("zonefs: open/close zone on file open/close")
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
>  fs/zonefs/super.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> index 0fe76f376dee..be6b99f7de74 100644
> --- a/fs/zonefs/super.c
> +++ b/fs/zonefs/super.c
> @@ -966,8 +966,7 @@ static int zonefs_open_zone(struct inode *inode)
>  
>  	mutex_lock(&zi->i_truncate_mutex);
>  
> -	zi->i_wr_refcnt++;
> -	if (zi->i_wr_refcnt == 1) {
> +	if (zi->i_wr_refcnt == 0) {

Nit: if (!zi->i_wr_refcnt) ? I can change that when applying.

>  
>  		if (atomic_inc_return(&sbi->s_open_zones) > sbi->s_max_open_zones) {
>  			atomic_dec(&sbi->s_open_zones);
> @@ -978,7 +977,6 @@ static int zonefs_open_zone(struct inode *inode)
>  		if (i_size_read(inode) < zi->i_max_size) {
>  			ret = zonefs_zone_mgmt(inode, REQ_OP_ZONE_OPEN);
>  			if (ret) {
> -				zi->i_wr_refcnt--;
>  				atomic_dec(&sbi->s_open_zones);
>  				goto unlock;
>  			}
> @@ -986,6 +984,8 @@ static int zonefs_open_zone(struct inode *inode)
>  		}
>  	}
>  
> +	zi->i_wr_refcnt++;
> +
>  unlock:
>  	mutex_unlock(&zi->i_truncate_mutex);
>  
> 

Good catch ! Will apply this and check zonefs test suite as this bug went
undetected.

Thanks.

-- 
Damien Le Moal
Western Digital Research