writeback, memcg: Implement cgroup_writeback_by_id() (d62241c7) · Commits · 戴 / test

fs/fs-writeback.c

+83 −0

Original line number	Diff line number	Diff line
		@@ -891,6 +891,89 @@ restart:
		wb_put(last_wb);
		}

		/**
		* 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, 0 for best-effort dirty flushing
		* @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;
		}

		/*
		* If @nr is zero, the caller is attempting to write out most of
		* the currently dirty pages. Let's take the current dirty page
		* count and inflate it by 25% which should be large enough to
		* flush out most dirty pages while avoiding getting livelocked by
		* concurrent dirtiers.
		*/
		if (!nr) {
		unsigned long filepages, headroom, dirty, writeback;

		mem_cgroup_wb_stats(wb, &filepages, &headroom, &dirty,
		&writeback);
		nr = dirty * 10 / 8;
		}

		/* 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->range_cyclic = 1;
		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
		*

include/linux/writeback.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -217,6 +217,8 @@ void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
		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);

		/**

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