1 files changed, 529 insertions, 0 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
new file mode 100644
index 000000000000..4bc6540d426b
--- /dev/null
+++ b/include/linux/backing-dev.h
@@ -0,0 +1,529 @@
+/*
+ * include/linux/backing-dev.h
+ *
+ * low-level device information and state which is propagated up through
+ * to high-level code.
+ */
+
+#ifndef _LINUX_BACKING_DEV_H
+#define _LINUX_BACKING_DEV_H
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/blkdev.h>
+#include <linux/writeback.h>
+#include <linux/blk-cgroup.h>
+#include <linux/backing-dev-defs.h>
+#include <linux/slab.h>
+
+int __must_check bdi_init(struct backing_dev_info *bdi);
+
+static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
+{
+	kref_get(&bdi->refcnt);
+	return bdi;
+}
+
+void bdi_put(struct backing_dev_info *bdi);
+
+__printf(3, 4)
+int bdi_register(struct backing_dev_info *bdi, struct device *parent,
+		const char *fmt, ...);
+int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
+int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
+void bdi_unregister(struct backing_dev_info *bdi);
+
+int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
+void bdi_destroy(struct backing_dev_info *bdi);
+struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
+
+void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
+			bool range_cyclic, enum wb_reason reason);
+void wb_start_background_writeback(struct bdi_writeback *wb);
+void wb_workfn(struct work_struct *work);
+void wb_wakeup_delayed(struct bdi_writeback *wb);
+
+extern spinlock_t bdi_lock;
+extern struct list_head bdi_list;
+
+extern struct workqueue_struct *bdi_wq;
+
+static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
+{
+	return test_bit(WB_has_dirty_io, &wb->state);
+}
+
+static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+	/*
+	 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
+	 * any dirty wbs.  See wb_update_write_bandwidth().
+	 */
+	return atomic_long_read(&bdi->tot_write_bandwidth);
+}
+
+static inline void __add_wb_stat(struct bdi_writeback *wb,
+				 enum wb_stat_item item, s64 amount)
+{
+	__percpu_counter_add(&wb->stat[item], amount, WB_STAT_BATCH);
+}
+
+static inline void __inc_wb_stat(struct bdi_writeback *wb,
+				 enum wb_stat_item item)
+{
+	__add_wb_stat(wb, item, 1);
+}
+
+static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__inc_wb_stat(wb, item);
+	local_irq_restore(flags);
+}
+
+static inline void __dec_wb_stat(struct bdi_writeback *wb,
+				 enum wb_stat_item item)
+{
+	__add_wb_stat(wb, item, -1);
+}
+
+static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	__dec_wb_stat(wb, item);
+	local_irq_restore(flags);
+}
+
+static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
+{
+	return percpu_counter_read_positive(&wb->stat[item]);
+}
+
+static inline s64 __wb_stat_sum(struct bdi_writeback *wb,
+				enum wb_stat_item item)
+{
+	return percpu_counter_sum_positive(&wb->stat[item]);
+}
+
+static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
+{
+	s64 sum;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	sum = __wb_stat_sum(wb, item);
+	local_irq_restore(flags);
+
+	return sum;
+}
+
+extern void wb_writeout_inc(struct bdi_writeback *wb);
+
+/*
+ * maximal error of a stat counter.
+ */
+static inline unsigned long wb_stat_error(struct bdi_writeback *wb)
+{
+#ifdef CONFIG_SMP
+	return nr_cpu_ids * WB_STAT_BATCH;
+#else
+	return 1;
+#endif
+}
+
+int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
+int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
+
+/*
+ * Flags in backing_dev_info::capability
+ *
+ * The first three flags control whether dirty pages will contribute to the
+ * VM's accounting and whether writepages() should be called for dirty pages
+ * (something that would not, for example, be appropriate for ramfs)
+ *
+ * WARNING: these flags are closely related and should not normally be
+ * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
+ * three flags into a single convenience macro.
+ *
+ * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
+ * BDI_CAP_NO_WRITEBACK:   Don't write pages back
+ * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
+ * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
+ *
+ * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
+ */
+#define BDI_CAP_NO_ACCT_DIRTY	0x00000001
+#define BDI_CAP_NO_WRITEBACK	0x00000002
+#define BDI_CAP_NO_ACCT_WB	0x00000004
+#define BDI_CAP_STABLE_WRITES	0x00000008
+#define BDI_CAP_STRICTLIMIT	0x00000010
+#define BDI_CAP_CGROUP_WRITEBACK 0x00000020
+
+#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
+	(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
+
+extern struct backing_dev_info noop_backing_dev_info;
+
+/**
+ * writeback_in_progress - determine whether there is writeback in progress
+ * @wb: bdi_writeback of interest
+ *
+ * Determine whether there is writeback waiting to be handled against a
+ * bdi_writeback.
+ */
+static inline bool writeback_in_progress(struct bdi_writeback *wb)
+{
+	return test_bit(WB_writeback_running, &wb->state);
+}
+
+static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
+{
+	struct super_block *sb;
+
+	if (!inode)
+		return &noop_backing_dev_info;
+
+	sb = inode->i_sb;
+#ifdef CONFIG_BLOCK
+	if (sb_is_blkdev_sb(sb))
+		return blk_get_backing_dev_info(I_BDEV(inode));
+#endif
+	return sb->s_bdi;
+}
+
+static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
+{
+	struct backing_dev_info *bdi = wb->bdi;
+
+	if (bdi->congested_fn)
+		return bdi->congested_fn(bdi->congested_data, cong_bits);
+	return wb->congested->state & cong_bits;
+}
+
+long congestion_wait(int sync, long timeout);
+long wait_iff_congested(struct zone *zone, int sync, long timeout);
+int pdflush_proc_obsolete(struct ctl_table *table, int write,
+		void __user *buffer, size_t *lenp, loff_t *ppos);
+
+static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
+{
+	return bdi->capabilities & BDI_CAP_STABLE_WRITES;
+}
+
+static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
+{
+	return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
+}
+
+static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
+{
+	return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
+}
+
+static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
+{
+	/* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
+	return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
+				      BDI_CAP_NO_WRITEBACK));
+}
+
+static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
+{
+	return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
+}
+
+static inline bool mapping_cap_account_dirty(struct address_space *mapping)
+{
+	return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
+}
+
+static inline int bdi_sched_wait(void *word)
+{
+	schedule();
+	return 0;
+}
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+struct bdi_writeback_congested *
+wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
+void wb_congested_put(struct bdi_writeback_congested *congested);
+struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
+				    struct cgroup_subsys_state *memcg_css,
+				    gfp_t gfp);
+void wb_memcg_offline(struct mem_cgroup *memcg);
+void wb_blkcg_offline(struct blkcg *blkcg);
+int inode_congested(struct inode *inode, int cong_bits);
+
+/**
+ * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
+ * @inode: inode of interest
+ *
+ * cgroup writeback requires support from both the bdi and filesystem.
+ * Also, both memcg and iocg have to be on the default hierarchy.  Test
+ * whether all conditions are met.
+ *
+ * Note that the test result may change dynamically on the same inode
+ * depending on how memcg and iocg are configured.
+ */
+static inline bool inode_cgwb_enabled(struct inode *inode)
+{
+	struct backing_dev_info *bdi = inode_to_bdi(inode);
+
+	return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
+		cgroup_subsys_on_dfl(io_cgrp_subsys) &&
+		bdi_cap_account_dirty(bdi) &&
+		(bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
+		(inode->i_sb->s_iflags & SB_I_CGROUPWB);
+}
+
+/**
+ * wb_find_current - find wb for %current on a bdi
+ * @bdi: bdi of interest
+ *
+ * Find the wb of @bdi which matches both the memcg and blkcg of %current.
+ * Must be called under rcu_read_lock() which protects the returend wb.
+ * NULL if not found.
+ */
+static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
+{
+	struct cgroup_subsys_state *memcg_css;
+	struct bdi_writeback *wb;
+
+	memcg_css = task_css(current, memory_cgrp_id);
+	if (!memcg_css->parent)
+		return &bdi->wb;
+
+	wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
+
+	/*
+	 * %current's blkcg equals the effective blkcg of its memcg.  No
+	 * need to use the relatively expensive cgroup_get_e_css().
+	 */
+	if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
+		return wb;
+	return NULL;
+}
+
+/**
+ * wb_get_create_current - get or create wb for %current on a bdi
+ * @bdi: bdi of interest
+ * @gfp: allocation mask
+ *
+ * Equivalent to wb_get_create() on %current's memcg.  This function is
+ * called from a relatively hot path and optimizes the common cases using
+ * wb_find_current().
+ */
+static inline struct bdi_writeback *
+wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
+{
+	struct bdi_writeback *wb;
+
+	rcu_read_lock();
+	wb = wb_find_current(bdi);
+	if (wb && unlikely(!wb_tryget(wb)))
+		wb = NULL;
+	rcu_read_unlock();
+
+	if (unlikely(!wb)) {
+		struct cgroup_subsys_state *memcg_css;
+
+		memcg_css = task_get_css(current, memory_cgrp_id);
+		wb = wb_get_create(bdi, memcg_css, gfp);
+		css_put(memcg_css);
+	}
+	return wb;
+}
+
+/**
+ * inode_to_wb_is_valid - test whether an inode has a wb associated
+ * @inode: inode of interest
+ *
+ * Returns %true if @inode has a wb associated.  May be called without any
+ * locking.
+ */
+static inline bool inode_to_wb_is_valid(struct inode *inode)
+{
+	return inode->i_wb;
+}
+
+/**
+ * inode_to_wb - determine the wb of an inode
+ * @inode: inode of interest
+ *
+ * Returns the wb @inode is currently associated with.  The caller must be
+ * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
+ * associated wb's list_lock.
+ */
+static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
+{
+#ifdef CONFIG_LOCKDEP
+	WARN_ON_ONCE(debug_locks &&
+		     (!lockdep_is_held(&inode->i_lock) &&
+		      !lockdep_is_held(&inode->i_mapping->tree_lock) &&
+		      !lockdep_is_held(&inode->i_wb->list_lock)));
+#endif
+	return inode->i_wb;
+}
+
+/**
+ * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
+ * @inode: target inode
+ * @cookie: output param, to be passed to the end function
+ *
+ * The caller wants to access the wb associated with @inode but isn't
+ * holding inode->i_lock, mapping->tree_lock or wb->list_lock.  This
+ * function determines the wb associated with @inode and ensures that the
+ * association doesn't change until the transaction is finished with
+ * unlocked_inode_to_wb_end().
+ *
+ * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
+ * can't sleep during the transaction.  IRQs may or may not be disabled on
+ * return.
+ */
+static inline struct bdi_writeback *
+unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
+{
+	rcu_read_lock();
+
+	/*
+	 * Paired with store_release in inode_switch_wb_work_fn() and
+	 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
+	 */
+	cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
+
+	if (unlikely(cookie->locked))
+		spin_lock_irqsave(&inode->i_mapping->tree_lock, cookie->flags);
+
+	/*
+	 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
+	 * inode_to_wb() will bark.  Deref directly.
+	 */
+	return inode->i_wb;
+}
+
+/**
+ * unlocked_inode_to_wb_end - end inode wb access transaction
+ * @inode: target inode
+ * @cookie: @cookie from unlocked_inode_to_wb_begin()
+ */
+static inline void unlocked_inode_to_wb_end(struct inode *inode,
+					    struct wb_lock_cookie *cookie)
+{
+	if (unlikely(cookie->locked))
+		spin_unlock_irqrestore(&inode->i_mapping->tree_lock,
+				       cookie->flags);
+
+	rcu_read_unlock();
+}
+
+#else	/* CONFIG_CGROUP_WRITEBACK */
+
+static inline bool inode_cgwb_enabled(struct inode *inode)
+{
+	return false;
+}
+
+static inline struct bdi_writeback_congested *
+wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
+{
+	atomic_inc(&bdi->wb_congested->refcnt);
+	return bdi->wb_congested;
+}
+
+static inline void wb_congested_put(struct bdi_writeback_congested *congested)
+{
+	if (atomic_dec_and_test(&congested->refcnt))
+		kfree(congested);
+}
+
+static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
+{
+	return &bdi->wb;
+}
+
+static inline struct bdi_writeback *
+wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
+{
+	return &bdi->wb;
+}
+
+static inline bool inode_to_wb_is_valid(struct inode *inode)
+{
+	return true;
+}
+
+static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
+{
+	return &inode_to_bdi(inode)->wb;
+}
+
+static inline struct bdi_writeback *
+unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
+{
+	return inode_to_wb(inode);
+}
+
+static inline void unlocked_inode_to_wb_end(struct inode *inode,
+					    struct wb_lock_cookie *cookie)
+{
+}
+
+static inline void wb_memcg_offline(struct mem_cgroup *memcg)
+{
+}
+
+static inline void wb_blkcg_offline(struct blkcg *blkcg)
+{
+}
+
+static inline int inode_congested(struct inode *inode, int cong_bits)
+{
+	return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
+}
+
+#endif	/* CONFIG_CGROUP_WRITEBACK */
+
+static inline int inode_read_congested(struct inode *inode)
+{
+	return inode_congested(inode, 1 << WB_sync_congested);
+}
+
+static inline int inode_write_congested(struct inode *inode)
+{
+	return inode_congested(inode, 1 << WB_async_congested);
+}
+
+static inline int inode_rw_congested(struct inode *inode)
+{
+	return inode_congested(inode, (1 << WB_sync_congested) |
+				      (1 << WB_async_congested));
+}
+
+static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
+{
+	return wb_congested(&bdi->wb, cong_bits);
+}
+
+static inline int bdi_read_congested(struct backing_dev_info *bdi)
+{
+	return bdi_congested(bdi, 1 << WB_sync_congested);
+}
+
+static inline int bdi_write_congested(struct backing_dev_info *bdi)
+{
+	return bdi_congested(bdi, 1 << WB_async_congested);
+}
+
+static inline int bdi_rw_congested(struct backing_dev_info *bdi)
+{
+	return bdi_congested(bdi, (1 << WB_sync_congested) |
+				  (1 << WB_async_congested));
+}
+
+#endif	/* _LINUX_BACKING_DEV_H */