1 files changed, 287 insertions, 95 deletions

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 4e198ca1f685..f48e8ccffe81 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * include/linux/writeback.h
  */
@@ -7,24 +8,22 @@
 #include <linux/sched.h>
 #include <linux/workqueue.h>
 #include <linux/fs.h>
+#include <linux/flex_proportions.h>
+#include <linux/backing-dev-defs.h>
+#include <linux/blk_types.h>
+#include <linux/pagevec.h>
+
+struct bio;
 
 DECLARE_PER_CPU(int, dirty_throttle_leaks);
 
 /*
- * The 1/4 region under the global dirty thresh is for smooth dirty throttling:
- *
- *	(thresh - thresh/DIRTY_FULL_SCOPE, thresh)
- *
- * Further beyond, all dirtier tasks will enter a loop waiting (possibly long
- * time) for the dirty pages to drop, unless written enough pages.
- *
  * The global dirty threshold is normally equal to the global dirty limit,
  * except when the system suddenly allocates a lot of anonymous memory and
  * knocks down the global dirty threshold quickly, in which case the global
  * dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
  */
 #define DIRTY_SCOPE		8
-#define DIRTY_FULL_SCOPE	(DIRTY_SCOPE / 2)
 
 struct backing_dev_info;
 
@@ -37,33 +36,12 @@ enum writeback_sync_modes {
 };
 
 /*
- * why some writeback work was initiated
- */
-enum wb_reason {
-	WB_REASON_BACKGROUND,
-	WB_REASON_TRY_TO_FREE_PAGES,
-	WB_REASON_SYNC,
-	WB_REASON_PERIODIC,
-	WB_REASON_LAPTOP_TIMER,
-	WB_REASON_FREE_MORE_MEM,
-	WB_REASON_FS_FREE_SPACE,
-	/*
-	 * There is no bdi forker thread any more and works are done
-	 * by emergency worker, however, this is TPs userland visible
-	 * and we'll be exposing exactly the same information,
-	 * so it has a mismatch name.
-	 */
-	WB_REASON_FORKER_THREAD,
-
-	WB_REASON_MAX,
-};
-
-/*
  * A control structure which tells the writeback code what to do.  These are
  * always on the stack, and hence need no locking.  They are always initialised
  * in a manner such that unspecified fields are set to zero.
  */
 struct writeback_control {
+	/* public fields that can be set and/or consumed by the caller: */
 	long nr_to_write;		/* Write this many pages, and decrement
 					   this for each page written */
 	long pages_skipped;		/* Pages which were not written */
@@ -81,110 +59,324 @@ struct writeback_control {
 	unsigned for_kupdate:1;		/* A kupdate writeback */
 	unsigned for_background:1;	/* A background writeback */
 	unsigned tagged_writepages:1;	/* tag-and-write to avoid livelock */
-	unsigned for_reclaim:1;		/* Invoked from the page allocator */
 	unsigned range_cyclic:1;	/* range_start is cyclic */
 	unsigned for_sync:1;		/* sync(2) WB_SYNC_ALL writeback */
+	unsigned unpinned_netfs_wb:1;	/* Cleared I_PINNING_NETFS_WB */
+
+	/*
+	 * When writeback IOs are bounced through async layers, only the
+	 * initial synchronous phase should be accounted towards inode
+	 * cgroup ownership arbitration to avoid confusion.  Later stages
+	 * can set the following flag to disable the accounting.
+	 */
+	unsigned no_cgroup_owner:1;
+
+	/* internal fields used by the ->writepages implementation: */
+	struct folio_batch fbatch;
+	pgoff_t index;
+	int saved_err;
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+	struct bdi_writeback *wb;	/* wb this writeback is issued under */
+	struct inode *inode;		/* inode being written out */
+
+	/* foreign inode detection, see wbc_detach_inode() */
+	int wb_id;			/* current wb id */
+	int wb_lcand_id;		/* last foreign candidate wb id */
+	int wb_tcand_id;		/* this foreign candidate wb id */
+	size_t wb_bytes;		/* bytes written by current wb */
+	size_t wb_lcand_bytes;		/* bytes written by last candidate */
+	size_t wb_tcand_bytes;		/* bytes written by this candidate */
+#endif
+};
+
+static inline blk_opf_t wbc_to_write_flags(struct writeback_control *wbc)
+{
+	blk_opf_t flags = 0;
+
+	if (wbc->sync_mode == WB_SYNC_ALL)
+		flags |= REQ_SYNC;
+	else if (wbc->for_kupdate || wbc->for_background)
+		flags |= REQ_BACKGROUND;
+
+	return flags;
+}
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+#define wbc_blkcg_css(wbc) \
+	((wbc)->wb ? (wbc)->wb->blkcg_css : blkcg_root_css)
+#else
+#define wbc_blkcg_css(wbc)		(blkcg_root_css)
+#endif /* CONFIG_CGROUP_WRITEBACK */
+
+/*
+ * A wb_domain represents a domain that wb's (bdi_writeback's) belong to
+ * and are measured against each other in.  There always is one global
+ * domain, global_wb_domain, that every wb in the system is a member of.
+ * This allows measuring the relative bandwidth of each wb to distribute
+ * dirtyable memory accordingly.
+ */
+struct wb_domain {
+	spinlock_t lock;
+
+	/*
+	 * Scale the writeback cache size proportional to the relative
+	 * writeout speed.
+	 *
+	 * We do this by keeping a floating proportion between BDIs, based
+	 * on page writeback completions [end_page_writeback()]. Those
+	 * devices that write out pages fastest will get the larger share,
+	 * while the slower will get a smaller share.
+	 *
+	 * We use page writeout completions because we are interested in
+	 * getting rid of dirty pages. Having them written out is the
+	 * primary goal.
+	 *
+	 * We introduce a concept of time, a period over which we measure
+	 * these events, because demand can/will vary over time. The length
+	 * of this period itself is measured in page writeback completions.
+	 */
+	struct fprop_global completions;
+	struct timer_list period_timer;	/* timer for aging of completions */
+	unsigned long period_time;
+
+	/*
+	 * The dirtyable memory and dirty threshold could be suddenly
+	 * knocked down by a large amount (eg. on the startup of KVM in a
+	 * swapless system). This may throw the system into deep dirty
+	 * exceeded state and throttle heavy/light dirtiers alike. To
+	 * retain good responsiveness, maintain global_dirty_limit for
+	 * tracking slowly down to the knocked down dirty threshold.
+	 *
+	 * Both fields are protected by ->lock.
+	 */
+	unsigned long dirty_limit_tstamp;
+	unsigned long dirty_limit;
 };
 
+/**
+ * wb_domain_size_changed - memory available to a wb_domain has changed
+ * @dom: wb_domain of interest
+ *
+ * This function should be called when the amount of memory available to
+ * @dom has changed.  It resets @dom's dirty limit parameters to prevent
+ * the past values which don't match the current configuration from skewing
+ * dirty throttling.  Without this, when memory size of a wb_domain is
+ * greatly reduced, the dirty throttling logic may allow too many pages to
+ * be dirtied leading to consecutive unnecessary OOMs and may get stuck in
+ * that situation.
+ */
+static inline void wb_domain_size_changed(struct wb_domain *dom)
+{
+	spin_lock(&dom->lock);
+	dom->dirty_limit_tstamp = jiffies;
+	dom->dirty_limit = 0;
+	spin_unlock(&dom->lock);
+}
+
 /*
  * fs/fs-writeback.c
  */	
 struct bdi_writeback;
-int inode_wait(void *);
 void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
 void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
 							enum wb_reason reason);
-int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
-int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
-				  enum wb_reason reason);
+void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason);
 void sync_inodes_sb(struct super_block *);
-long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
+void wakeup_flusher_threads(enum wb_reason reason);
+void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
 				enum wb_reason reason);
-void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
 void inode_wait_for_writeback(struct inode *inode);
+void inode_io_list_del(struct inode *inode);
 
-/* writeback.h requires fs.h; it, too, is not included from here. */
-static inline void wait_on_inode(struct inode *inode)
+static inline xa_mark_t wbc_to_tag(struct writeback_control *wbc)
 {
-	might_sleep();
-	wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		return PAGECACHE_TAG_TOWRITE;
+	return PAGECACHE_TAG_DIRTY;
 }
 
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+#include <linux/cgroup.h>
+#include <linux/bio.h>
+
+void __inode_attach_wb(struct inode *inode, struct folio *folio);
+void wbc_detach_inode(struct writeback_control *wbc);
+void wbc_account_cgroup_owner(struct writeback_control *wbc, struct folio *folio,
+			      size_t bytes);
+int cgroup_writeback_by_id(u64 bdi_id, int memcg_id,
+			   enum wb_reason reason, struct wb_completion *done);
+void cgroup_writeback_umount(struct super_block *sb);
+bool cleanup_offline_cgwb(struct bdi_writeback *wb);
+
+/**
+ * inode_attach_wb - associate an inode with its wb
+ * @inode: inode of interest
+ * @folio: folio being dirtied (may be NULL)
+ *
+ * If @inode doesn't have its wb, associate it with the wb matching the
+ * memcg of @folio or, if @folio is NULL, %current.  May be called w/ or w/o
+ * @inode->i_lock.
+ */
+static inline void inode_attach_wb(struct inode *inode, struct folio *folio)
+{
+	if (!inode->i_wb)
+		__inode_attach_wb(inode, folio);
+}
+
+/**
+ * inode_detach_wb - disassociate an inode from its wb
+ * @inode: inode of interest
+ *
+ * @inode is being freed.  Detach from its wb.
+ */
+static inline void inode_detach_wb(struct inode *inode)
+{
+	if (inode->i_wb) {
+		WARN_ON_ONCE(!(inode_state_read_once(inode) & I_CLEAR));
+		wb_put(inode->i_wb);
+		inode->i_wb = NULL;
+	}
+}
+
+void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
+		struct inode *inode);
+
+/**
+ * wbc_init_bio - writeback specific initializtion of bio
+ * @wbc: writeback_control for the writeback in progress
+ * @bio: bio to be initialized
+ *
+ * @bio is a part of the writeback in progress controlled by @wbc.  Perform
+ * writeback specific initialization.  This is used to apply the cgroup
+ * writeback context.  Must be called after the bio has been associated with
+ * a device.
+ */
+static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
+{
+	/*
+	 * pageout() path doesn't attach @wbc to the inode being written
+	 * out.  This is intentional as we don't want the function to block
+	 * behind a slow cgroup.  Ultimately, we want pageout() to kick off
+	 * regular writeback instead of writing things out itself.
+	 */
+	if (wbc->wb)
+		bio_associate_blkg_from_css(bio, wbc->wb->blkcg_css);
+}
+
+void inode_switch_wbs_work_fn(struct work_struct *work);
+
+#else	/* CONFIG_CGROUP_WRITEBACK */
+
+static inline void inode_attach_wb(struct inode *inode, struct folio *folio)
+{
+}
+
+static inline void inode_detach_wb(struct inode *inode)
+{
+}
+
+static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
+					       struct inode *inode)
+{
+}
+
+static inline void wbc_detach_inode(struct writeback_control *wbc)
+{
+}
+
+static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
+{
+}
+
+static inline void wbc_account_cgroup_owner(struct writeback_control *wbc,
+					    struct folio *folio, size_t bytes)
+{
+}
+
+static inline void cgroup_writeback_umount(struct super_block *sb)
+{
+}
+
+#endif	/* CONFIG_CGROUP_WRITEBACK */
+
 /*
  * mm/page-writeback.c
  */
-#ifdef CONFIG_BLOCK
+/* consolidated parameters for balance_dirty_pages() and its subroutines */
+struct dirty_throttle_control {
+#ifdef CONFIG_CGROUP_WRITEBACK
+	struct wb_domain	*dom;
+	struct dirty_throttle_control *gdtc;	/* only set in memcg dtc's */
+#endif
+	struct bdi_writeback	*wb;
+	struct fprop_local_percpu *wb_completions;
+
+	unsigned long		avail;		/* dirtyable */
+	unsigned long		dirty;		/* file_dirty + write + nfs */
+	unsigned long		thresh;		/* dirty threshold */
+	unsigned long		bg_thresh;	/* dirty background threshold */
+	unsigned long		limit;		/* hard dirty limit */
+
+	unsigned long		wb_dirty;	/* per-wb counterparts */
+	unsigned long		wb_thresh;
+	unsigned long		wb_bg_thresh;
+
+	unsigned long		pos_ratio;
+	bool			freerun;
+	bool			dirty_exceeded;
+};
+
 void laptop_io_completion(struct backing_dev_info *info);
 void laptop_sync_completion(void);
-void laptop_mode_sync(struct work_struct *work);
-void laptop_mode_timer_fn(unsigned long data);
-#else
-static inline void laptop_sync_completion(void) { }
+void laptop_mode_timer_fn(struct timer_list *t);
+bool node_dirty_ok(struct pglist_data *pgdat);
+int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
+#ifdef CONFIG_CGROUP_WRITEBACK
+void wb_domain_exit(struct wb_domain *dom);
 #endif
-void throttle_vm_writeout(gfp_t gfp_mask);
-bool zone_dirty_ok(struct zone *zone);
 
-extern unsigned long global_dirty_limit;
+extern struct wb_domain global_wb_domain;
 
 /* These are exported to sysctl. */
-extern int dirty_background_ratio;
-extern unsigned long dirty_background_bytes;
-extern int vm_dirty_ratio;
-extern unsigned long vm_dirty_bytes;
 extern unsigned int dirty_writeback_interval;
 extern unsigned int dirty_expire_interval;
-extern int vm_highmem_is_dirtyable;
-extern int block_dump;
 extern int laptop_mode;
 
-extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-extern int dirty_ratio_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-extern int dirty_bytes_handler(struct ctl_table *table, int write,
-		void __user *buffer, size_t *lenp,
-		loff_t *ppos);
-
-struct ctl_table;
-int dirty_writeback_centisecs_handler(struct ctl_table *, int,
-				      void __user *, size_t *, loff_t *);
-
 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
-unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
-			       unsigned long dirty);
-
-void __bdi_update_bandwidth(struct backing_dev_info *bdi,
-			    unsigned long thresh,
-			    unsigned long bg_thresh,
-			    unsigned long dirty,
-			    unsigned long bdi_thresh,
-			    unsigned long bdi_dirty,
-			    unsigned long start_time);
-
-void page_writeback_init(void);
+unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);
+unsigned long cgwb_calc_thresh(struct bdi_writeback *wb);
+
+void wb_update_bandwidth(struct bdi_writeback *wb);
+
+/* Invoke balance dirty pages in async mode. */
+#define BDP_ASYNC 0x0001
+
 void balance_dirty_pages_ratelimited(struct address_space *mapping);
+int balance_dirty_pages_ratelimited_flags(struct address_space *mapping,
+		unsigned int flags);
 
-typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
-				void *data);
+bool wb_over_bg_thresh(struct bdi_writeback *wb);
+
+struct folio *writeback_iter(struct address_space *mapping,
+		struct writeback_control *wbc, struct folio *folio, int *error);
 
-int generic_writepages(struct address_space *mapping,
-		       struct writeback_control *wbc);
-void tag_pages_for_writeback(struct address_space *mapping,
-			     pgoff_t start, pgoff_t end);
-int write_cache_pages(struct address_space *mapping,
-		      struct writeback_control *wbc, writepage_t writepage,
-		      void *data);
 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
-void set_page_dirty_balance(struct page *page, int page_mkwrite);
 void writeback_set_ratelimit(void);
 void tag_pages_for_writeback(struct address_space *mapping,
 			     pgoff_t start, pgoff_t end);
 
-void account_page_redirty(struct page *page);
+bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio);
+bool folio_redirty_for_writepage(struct writeback_control *, struct folio *);
+bool redirty_page_for_writepage(struct writeback_control *, struct page *);
+
+void sb_mark_inode_writeback(struct inode *inode);
+void sb_clear_inode_writeback(struct inode *inode);
+
+/*
+ * 4MB minimal write chunk size
+ */
+#define MIN_WRITEBACK_PAGES	(4096UL >> (PAGE_SHIFT - 10))
 
 #endif		/* WRITEBACK_H */