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Message-ID: <5f1b85b8-3655-1700-4d16-fa056b31ceeb@bytedance.com>
Date:   Thu, 27 Jul 2023 17:19:49 +0800
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Subject: Re: [PATCH v3 40/49] xfs: dynamically allocate the xfs-qm shrinker
Content-Language: en-US
To:     akpm@linux-foundation.org, david@fromorbit.com, tkhai@ya.ru,
        vbabka@suse.cz, roman.gushchin@linux.dev, djwong@kernel.org,
        brauner@kernel.org, paulmck@kernel.org, tytso@mit.edu,
        steven.price@arm.com, cel@kernel.org, senozhatsky@chromium.org,
        yujie.liu@intel.com, gregkh@linuxfoundation.org,
        muchun.song@linux.dev
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
        kvm@vger.kernel.org, xen-devel@lists.xenproject.org,
        linux-erofs@lists.ozlabs.org,
        linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com,
        linux-nfs@vger.kernel.org, linux-mtd@lists.infradead.org,
        rcu@vger.kernel.org, netdev@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        dm-devel@redhat.com, linux-raid@vger.kernel.org,
        linux-bcache@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
        linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org,
        Muchun Song <songmuchun@bytedance.com>
References: <20230727080502.77895-1-zhengqi.arch@bytedance.com>
 <20230727080502.77895-41-zhengqi.arch@bytedance.com>
From:   Qi Zheng <zhengqi.arch@bytedance.com>
In-Reply-To: <20230727080502.77895-41-zhengqi.arch@bytedance.com>
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On 2023/7/27 16:04, Qi Zheng wrote:
> In preparation for implementing lockless slab shrink, use new APIs to
> dynamically allocate the xfs-qm shrinker, so that it can be freed
> asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
> read-side critical section when releasing the struct xfs_quotainfo.
> 
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
> ---
>   fs/xfs/xfs_qm.c | 26 +++++++++++++-------------
>   fs/xfs/xfs_qm.h |  2 +-
>   2 files changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
> index 6abcc34fafd8..032f0a208bd2 100644
> --- a/fs/xfs/xfs_qm.c
> +++ b/fs/xfs/xfs_qm.c
> @@ -504,8 +504,7 @@ xfs_qm_shrink_scan(
>   	struct shrinker		*shrink,
>   	struct shrink_control	*sc)
>   {
> -	struct xfs_quotainfo	*qi = container_of(shrink,
> -					struct xfs_quotainfo, qi_shrinker);
> +	struct xfs_quotainfo	*qi = shrink->private_data;
>   	struct xfs_qm_isolate	isol;
>   	unsigned long		freed;
>   	int			error;
> @@ -539,8 +538,7 @@ xfs_qm_shrink_count(
>   	struct shrinker		*shrink,
>   	struct shrink_control	*sc)
>   {
> -	struct xfs_quotainfo	*qi = container_of(shrink,
> -					struct xfs_quotainfo, qi_shrinker);
> +	struct xfs_quotainfo	*qi = shrink->private_data;
>   
>   	return list_lru_shrink_count(&qi->qi_lru, sc);
>   }
> @@ -680,16 +678,18 @@ xfs_qm_init_quotainfo(
>   	if (XFS_IS_PQUOTA_ON(mp))
>   		xfs_qm_set_defquota(mp, XFS_DQTYPE_PROJ, qinf);
>   
> -	qinf->qi_shrinker.count_objects = xfs_qm_shrink_count;
> -	qinf->qi_shrinker.scan_objects = xfs_qm_shrink_scan;
> -	qinf->qi_shrinker.seeks = DEFAULT_SEEKS;
> -	qinf->qi_shrinker.flags = SHRINKER_NUMA_AWARE;
> -
> -	error = register_shrinker(&qinf->qi_shrinker, "xfs-qm:%s",
> -				  mp->m_super->s_id);
> -	if (error)
> +	qinf->qi_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-qm:%s",
> +					   mp->m_super->s_id);
> +	if (!qinf->qi_shrinker)

Here should set error to -ENOMEM, will fix.

>   		goto out_free_inos;
>   
> +	qinf->qi_shrinker->count_objects = xfs_qm_shrink_count;
> +	qinf->qi_shrinker->scan_objects = xfs_qm_shrink_scan;
> +	qinf->qi_shrinker->seeks = DEFAULT_SEEKS;
> +	qinf->qi_shrinker->private_data = qinf;
> +
> +	shrinker_register(qinf->qi_shrinker);
> +
>   	return 0;
>   
>   out_free_inos:
> @@ -718,7 +718,7 @@ xfs_qm_destroy_quotainfo(
>   	qi = mp->m_quotainfo;
>   	ASSERT(qi != NULL);
>   
> -	unregister_shrinker(&qi->qi_shrinker);
> +	shrinker_free(qi->qi_shrinker);
>   	list_lru_destroy(&qi->qi_lru);
>   	xfs_qm_destroy_quotainos(qi);
>   	mutex_destroy(&qi->qi_tree_lock);
> diff --git a/fs/xfs/xfs_qm.h b/fs/xfs/xfs_qm.h
> index 9683f0457d19..d5c9fc4ba591 100644
> --- a/fs/xfs/xfs_qm.h
> +++ b/fs/xfs/xfs_qm.h
> @@ -63,7 +63,7 @@ struct xfs_quotainfo {
>   	struct xfs_def_quota	qi_usr_default;
>   	struct xfs_def_quota	qi_grp_default;
>   	struct xfs_def_quota	qi_prj_default;
> -	struct shrinker		qi_shrinker;
> +	struct shrinker		*qi_shrinker;
>   
>   	/* Minimum and maximum quota expiration timestamp values. */
>   	time64_t		qi_expiry_min;