linux-ext4 - Re: [PATCH 22/50] fs: use inode_tryget in find

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250825-seicht-anfassen-6c0235f32224@brauner>
Date: Mon, 25 Aug 2025 13:26:00 +0200
From: Christian Brauner <brauner@...nel.org>
To: Josef Bacik <josef@...icpanda.com>
Cc: linux-fsdevel@...r.kernel.org, linux-btrfs@...r.kernel.org, 
	kernel-team@...com, linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org, 
	viro@...iv.linux.org.uk
Subject: Re: [PATCH 22/50] fs: use inode_tryget in find_inode*

On Thu, Aug 21, 2025 at 04:18:33PM -0400, Josef Bacik wrote:
> Now that we never drop the i_count to 0 for valid objects, rework the
> logic in the find_inode* helpers to use inode_tryget() to see if they
> have a live inode.  If this fails we can wait for the inode to be freed
> as we know it's currently being evicted.
> 
> Signed-off-by: Josef Bacik <josef@...icpanda.com>
> ---
>  fs/inode.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index b9122c1eee1d..893ac902268b 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1109,6 +1109,7 @@ long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
>  }
>  
>  static void __wait_on_freeing_inode(struct inode *inode, bool is_inode_hash_locked);
> +
>  /*
>   * Called with the inode lock held.
>   */
> @@ -1132,16 +1133,15 @@ static struct inode *find_inode(struct super_block *sb,
>  		if (!test(inode, data))
>  			continue;
>  		spin_lock(&inode->i_lock);
> -		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
> -			__wait_on_freeing_inode(inode, is_inode_hash_locked);
> -			goto repeat;
> -		}
>  		if (unlikely(inode->i_state & I_CREATING)) {
>  			spin_unlock(&inode->i_lock);
>  			rcu_read_unlock();
>  			return ERR_PTR(-ESTALE);
>  		}
> -		__iget(inode);
> +		if (!inode_tryget(inode)) {
> +			__wait_on_freeing_inode(inode, is_inode_hash_locked);
> +			goto repeat;
> +		}
>  		inode_lru_list_del(inode);
>  		spin_unlock(&inode->i_lock);
>  		rcu_read_unlock();
> @@ -1174,16 +1174,15 @@ static struct inode *find_inode_fast(struct super_block *sb,
>  		if (inode->i_sb != sb)
>  			continue;
>  		spin_lock(&inode->i_lock);
> -		if (inode->i_state & (I_FREEING|I_WILL_FREE)) {

Oh yes, this is such a beautiful change...

> -			__wait_on_freeing_inode(inode, is_inode_hash_locked);
> -			goto repeat;
> -		}


>  		if (unlikely(inode->i_state & I_CREATING)) {
>  			spin_unlock(&inode->i_lock);
>  			rcu_read_unlock();
>  			return ERR_PTR(-ESTALE);
>  		}
> -		__iget(inode);
> +		if (!inode_tryget(inode)) {
> +			__wait_on_freeing_inode(inode, is_inode_hash_locked);
> +			goto repeat;
> +		}
>  		inode_lru_list_del(inode);
>  		spin_unlock(&inode->i_lock);
>  		rcu_read_unlock();
> -- 
> 2.49.0
>