linux-kernel - Re: [Linux-cachefs] [PATCH] fscache: Fix if condition in fscache_wait_on_volume

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Message-ID: <243e8ec016b415d71849d8d5c92394ef67a8ca04.camel@kernel.org>
Date:   Tue, 05 Jul 2022 10:59:45 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Yue Hu <huyue2@...lpad.com>, dhowells@...hat.com,
        linux-cachefs@...hat.com
Cc:     zhangwen@...lpad.com, linux-kernel@...r.kernel.org,
        zbestahu@...il.com
Subject: Re: [Linux-cachefs] [PATCH] fscache: Fix if condition in
 fscache_wait_on_volume_collision()

On Wed, 2022-05-25 at 10:32 +0800, Yue Hu wrote:
> After waiting for the volume to complete the acquisition with timeout,
> the if condition under which potential volume collision occurs should be
> acquire the volume is still pending rather than not pending so that we
> will continue to wait until the pending flag is cleared. Also, use the
> existing test pending wrapper directly instead of test_bit().
> 
> Signed-off-by: Yue Hu <huyue2@...lpad.com>
> ---
>  fs/fscache/volume.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/fscache/volume.c b/fs/fscache/volume.c
> index 71d3a6d6d72c..f2009cc22002 100644
> --- a/fs/fscache/volume.c
> +++ b/fs/fscache/volume.c
> @@ -143,7 +143,7 @@ static void fscache_wait_on_volume_collision(struct fscache_volume *candidate,
>  {
>  	wait_var_event_timeout(&candidate->flags,
>  			       !fscache_is_acquire_pending(candidate), 20 * HZ);
> -	if (!fscache_is_acquire_pending(candidate)) {
> +	if (fscache_is_acquire_pending(candidate)) {
>  		pr_notice("Potential volume collision new=%08x old=%08x",
>  			  candidate->debug_id, collidee_debug_id);
>  		fscache_stat(&fscache_n_volumes_collision);
> @@ -182,7 +182,7 @@ static bool fscache_hash_volume(struct fscache_volume *candidate)
>  	hlist_bl_add_head(&candidate->hash_link, h);
>  	hlist_bl_unlock(h);
>  
> -	if (test_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &candidate->flags))
> +	if (fscache_is_acquire_pending(candidate))
>  		fscache_wait_on_volume_collision(candidate, collidee_debug_id);
>  	return true;
>  

Nice catch:

Reviewed-by: Jeff Layton <jlayton@...nel.org>