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From: Jan Kara <jack@suse.cz>
To: Tejun Heo <tj@kernel.org>
Cc: axboe@kernel.dk, jack@suse.cz, hannes@cmpxchg.org,
	mhocko@kernel.org, vdavydov.dev@gmail.com,
	cgroups@vger.kernel.org, linux-mm@kvack.org,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com, guro@fb.com, akpm@linux-foundation.org
Subject: Re: [PATCH 4/5] writeback, memcg: Implement cgroup_writeback_by_id()
Date: Fri, 16 Aug 2019 17:47:09 +0200
Message-ID: <20190816154709.GH3041@quack2.suse.cz> (raw)
In-Reply-To: <20190815195902.GE2263813@devbig004.ftw2.facebook.com>

On Thu 15-08-19 12:59:02, Tejun Heo wrote:
> Implement cgroup_writeback_by_id() which initiates cgroup writeback
> from bdi and memcg IDs.  This will be used by memcg foreign inode
> flushing.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza


> ---
>  fs/fs-writeback.c         |   67 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/writeback.h |    2 +
>  2 files changed, 69 insertions(+)
> 
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -892,6 +892,73 @@ restart:
>  }
>  
>  /**
> + * cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs
> + * @bdi_id: target bdi id
> + * @memcg_id: target memcg css id
> + * @nr_pages: number of pages to write
> + * @reason: reason why some writeback work initiated
> + * @done: target wb_completion
> + *
> + * Initiate flush of the bdi_writeback identified by @bdi_id and @memcg_id
> + * with the specified parameters.
> + */
> +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr,
> +			   enum wb_reason reason, struct wb_completion *done)
> +{
> +	struct backing_dev_info *bdi;
> +	struct cgroup_subsys_state *memcg_css;
> +	struct bdi_writeback *wb;
> +	struct wb_writeback_work *work;
> +	int ret;
> +
> +	/* lookup bdi and memcg */
> +	bdi = bdi_get_by_id(bdi_id);
> +	if (!bdi)
> +		return -ENOENT;
> +
> +	rcu_read_lock();
> +	memcg_css = css_from_id(memcg_id, &memory_cgrp_subsys);
> +	if (memcg_css && !css_tryget(memcg_css))
> +		memcg_css = NULL;
> +	rcu_read_unlock();
> +	if (!memcg_css) {
> +		ret = -ENOENT;
> +		goto out_bdi_put;
> +	}
> +
> +	/*
> +	 * And find the associated wb.  If the wb isn't there already
> +	 * there's nothing to flush, don't create one.
> +	 */
> +	wb = wb_get_lookup(bdi, memcg_css);
> +	if (!wb) {
> +		ret = -ENOENT;
> +		goto out_css_put;
> +	}
> +
> +	/* issue the writeback work */
> +	work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN);
> +	if (work) {
> +		work->nr_pages = nr;
> +		work->sync_mode = WB_SYNC_NONE;
> +		work->reason = reason;
> +		work->done = done;
> +		work->auto_free = 1;
> +		wb_queue_work(wb, work);
> +		ret = 0;
> +	} else {
> +		ret = -ENOMEM;
> +	}
> +
> +	wb_put(wb);
> +out_css_put:
> +	css_put(memcg_css);
> +out_bdi_put:
> +	bdi_put(bdi);
> +	return ret;
> +}
> +
> +/**
>   * cgroup_writeback_umount - flush inode wb switches for umount
>   *
>   * This function is called when a super_block is about to be destroyed and
> --- a/include/linux/writeback.h
> +++ b/include/linux/writeback.h
> @@ -217,6 +217,8 @@ void wbc_attach_and_unlock_inode(struct
>  void wbc_detach_inode(struct writeback_control *wbc);
>  void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page,
>  			      size_t bytes);
> +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr_pages,
> +			   enum wb_reason reason, struct wb_completion *done);
>  void cgroup_writeback_umount(void);
>  
>  /**
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-15 19:56 [PATCHSET v2] writeback, memcg: Implement foreign inode flushing Tejun Heo
2019-08-15 19:57 ` [PATCH 1/5] writeback: Generalize and expose wb_completion Tejun Heo
2019-08-15 19:57 ` [PATCH 2/5] bdi: Add bdi->id Tejun Heo
2019-08-15 19:58 ` [PATCH 3/5] writeback: Separate out wb_get_lookup() from wb_get_create() Tejun Heo
2019-08-16 15:45   ` Jan Kara
2019-08-15 19:59 ` [PATCH 4/5] writeback, memcg: Implement cgroup_writeback_by_id() Tejun Heo
2019-08-16 15:47   ` Jan Kara [this message]
2019-08-21 21:02   ` [PATCH v3 " Tejun Heo
2019-08-26 13:49     ` Jan Kara
2019-08-15 19:59 ` [PATCH 5/5] writeback, memcg: Implement foreign dirty flushing Tejun Heo
2019-08-16 16:02   ` Jan Kara
2019-08-21 16:00     ` Tejun Heo
2019-08-21 16:04       ` Tejun Heo
2019-08-21 21:02   ` [PATCH v3 " Tejun Heo
2019-08-26 13:54     ` Jan Kara
2019-08-26 15:58       ` Tejun Heo
2019-08-26 16:06 [PATCHSET v3] writeback, memcg: Implement foreign inode flushing Tejun Heo
2019-08-26 16:06 ` [PATCH 4/5] writeback, memcg: Implement cgroup_writeback_by_id() Tejun Heo

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