Merge commit 'v2.6.32' into reiserfs/kill-bkl

Merge-reason: The tree was based 2.6.31. It's better to be up to date
with 2.6.32. Although no conflicting changes were made in between,
it gives benchmarking results closer to the lastest kernel behaviour.

1 files changed, 843 insertions, 354 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index c54226b..9d5360c 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -19,171 +19,257 @@
 #include <linux/sched.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
 #include <linux/writeback.h>
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
 #include <linux/buffer_head.h>
 #include "internal.h"
 
+#define inode_to_bdi(inode)	((inode)->i_mapping->backing_dev_info)
 
-/**
- * writeback_acquire - attempt to get exclusive writeback access to a device
- * @bdi: the device's backing_dev_info structure
- *
- * It is a waste of resources to have more than one pdflush thread blocked on
- * a single request queue.  Exclusion at the request_queue level is obtained
- * via a flag in the request_queue's backing_dev_info.state.
- *
- * Non-request_queue-backed address_spaces will share default_backing_dev_info,
- * unless they implement their own.  Which is somewhat inefficient, as this
- * may prevent concurrent writeback against multiple devices.
+/*
+ * We don't actually have pdflush, but this one is exported though /proc...
  */
-static int writeback_acquire(struct backing_dev_info *bdi)
+int nr_pdflush_threads;
+
+/*
+ * Passed into wb_writeback(), essentially a subset of writeback_control
+ */
+struct wb_writeback_args {
+	long nr_pages;
+	struct super_block *sb;
+	enum writeback_sync_modes sync_mode;
+	int for_kupdate:1;
+	int range_cyclic:1;
+	int for_background:1;
+};
+
+/*
+ * Work items for the bdi_writeback threads
+ */
+struct bdi_work {
+	struct list_head list;		/* pending work list */
+	struct rcu_head rcu_head;	/* for RCU free/clear of work */
+
+	unsigned long seen;		/* threads that have seen this work */
+	atomic_t pending;		/* number of threads still to do work */
+
+	struct wb_writeback_args args;	/* writeback arguments */
+
+	unsigned long state;		/* flag bits, see WS_* */
+};
+
+enum {
+	WS_USED_B = 0,
+	WS_ONSTACK_B,
+};
+
+#define WS_USED (1 << WS_USED_B)
+#define WS_ONSTACK (1 << WS_ONSTACK_B)
+
+static inline bool bdi_work_on_stack(struct bdi_work *work)
 {
-	return !test_and_set_bit(BDI_pdflush, &bdi->state);
+	return test_bit(WS_ONSTACK_B, &work->state);
+}
+
+static inline void bdi_work_init(struct bdi_work *work,
+				 struct wb_writeback_args *args)
+{
+	INIT_RCU_HEAD(&work->rcu_head);
+	work->args = *args;
+	work->state = WS_USED;
 }
 
 /**
  * writeback_in_progress - determine whether there is writeback in progress
  * @bdi: the device's backing_dev_info structure.
  *
- * Determine whether there is writeback in progress against a backing device.
+ * Determine whether there is writeback waiting to be handled against a
+ * backing device.
  */
 int writeback_in_progress(struct backing_dev_info *bdi)
 {
-	return test_bit(BDI_pdflush, &bdi->state);
+	return !list_empty(&bdi->work_list);
 }
 
-/**
- * writeback_release - relinquish exclusive writeback access against a device.
- * @bdi: the device's backing_dev_info structure
- */
-static void writeback_release(struct backing_dev_info *bdi)
+static void bdi_work_clear(struct bdi_work *work)
 {
-	BUG_ON(!writeback_in_progress(bdi));
-	clear_bit(BDI_pdflush, &bdi->state);
+	clear_bit(WS_USED_B, &work->state);
+	smp_mb__after_clear_bit();
+	/*
+	 * work can have disappeared at this point. bit waitq functions
+	 * should be able to tolerate this, provided bdi_sched_wait does
+	 * not dereference it's pointer argument.
+	*/
+	wake_up_bit(&work->state, WS_USED_B);
 }
 
-static noinline void block_dump___mark_inode_dirty(struct inode *inode)
+static void bdi_work_free(struct rcu_head *head)
 {
-	if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) {
-		struct dentry *dentry;
-		const char *name = "?";
+	struct bdi_work *work = container_of(head, struct bdi_work, rcu_head);
 
-		dentry = d_find_alias(inode);
-		if (dentry) {
-			spin_lock(&dentry->d_lock);
-			name = (const char *) dentry->d_name.name;
-		}
-		printk(KERN_DEBUG
-		       "%s(%d): dirtied inode %lu (%s) on %s\n",
-		       current->comm, task_pid_nr(current), inode->i_ino,
-		       name, inode->i_sb->s_id);
-		if (dentry) {
-			spin_unlock(&dentry->d_lock);
-			dput(dentry);
-		}
-	}
+	if (!bdi_work_on_stack(work))
+		kfree(work);
+	else
+		bdi_work_clear(work);
 }
 
-/**
- *	__mark_inode_dirty -	internal function
- *	@inode: inode to mark
- *	@flags: what kind of dirty (i.e. I_DIRTY_SYNC)
- *	Mark an inode as dirty. Callers should use mark_inode_dirty or
- *  	mark_inode_dirty_sync.
- *
- * Put the inode on the super block's dirty list.
- *
- * CAREFUL! We mark it dirty unconditionally, but move it onto the
- * dirty list only if it is hashed or if it refers to a blockdev.
- * If it was not hashed, it will never be added to the dirty list
- * even if it is later hashed, as it will have been marked dirty already.
- *
- * In short, make sure you hash any inodes _before_ you start marking
- * them dirty.
- *
- * This function *must* be atomic for the I_DIRTY_PAGES case -
- * set_page_dirty() is called under spinlock in several places.
- *
- * Note that for blockdevs, inode->dirtied_when represents the dirtying time of
- * the block-special inode (/dev/hda1) itself.  And the ->dirtied_when field of
- * the kernel-internal blockdev inode represents the dirtying time of the
- * blockdev's pages.  This is why for I_DIRTY_PAGES we always use
- * page->mapping->host, so the page-dirtying time is recorded in the internal
- * blockdev inode.
- */
-void __mark_inode_dirty(struct inode *inode, int flags)
+static void wb_work_complete(struct bdi_work *work)
 {
-	struct super_block *sb = inode->i_sb;
+	const enum writeback_sync_modes sync_mode = work->args.sync_mode;
+	int onstack = bdi_work_on_stack(work);
 
 	/*
-	 * Don't do this for I_DIRTY_PAGES - that doesn't actually
-	 * dirty the inode itself
+	 * For allocated work, we can clear the done/seen bit right here.
+	 * For on-stack work, we need to postpone both the clear and free
+	 * to after the RCU grace period, since the stack could be invalidated
+	 * as soon as bdi_work_clear() has done the wakeup.
 	 */
-	if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
-		if (sb->s_op->dirty_inode)
-			sb->s_op->dirty_inode(inode);
-	}
+	if (!onstack)
+		bdi_work_clear(work);
+	if (sync_mode == WB_SYNC_NONE || onstack)
+		call_rcu(&work->rcu_head, bdi_work_free);
+}
 
+static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work)
+{
 	/*
-	 * make sure that changes are seen by all cpus before we test i_state
-	 * -- mikulas
+	 * The caller has retrieved the work arguments from this work,
+	 * drop our reference. If this is the last ref, delete and free it
 	 */
-	smp_mb();
+	if (atomic_dec_and_test(&work->pending)) {
+		struct backing_dev_info *bdi = wb->bdi;
 
-	/* avoid the locking if we can */
-	if ((inode->i_state & flags) == flags)
-		return;
+		spin_lock(&bdi->wb_lock);
+		list_del_rcu(&work->list);
+		spin_unlock(&bdi->wb_lock);
 
-	if (unlikely(block_dump))
-		block_dump___mark_inode_dirty(inode);
+		wb_work_complete(work);
+	}
+}
 
-	spin_lock(&inode_lock);
-	if ((inode->i_state & flags) != flags) {
-		const int was_dirty = inode->i_state & I_DIRTY;
+static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work)
+{
+	work->seen = bdi->wb_mask;
+	BUG_ON(!work->seen);
+	atomic_set(&work->pending, bdi->wb_cnt);
+	BUG_ON(!bdi->wb_cnt);
 
-		inode->i_state |= flags;
+	/*
+	 * list_add_tail_rcu() contains the necessary barriers to
+	 * make sure the above stores are seen before the item is
+	 * noticed on the list
+	 */
+	spin_lock(&bdi->wb_lock);
+	list_add_tail_rcu(&work->list, &bdi->work_list);
+	spin_unlock(&bdi->wb_lock);
 
-		/*
-		 * If the inode is being synced, just update its dirty state.
-		 * The unlocker will place the inode on the appropriate
-		 * superblock list, based upon its state.
-		 */
-		if (inode->i_state & I_SYNC)
-			goto out;
+	/*
+	 * If the default thread isn't there, make sure we add it. When
+	 * it gets created and wakes up, we'll run this work.
+	 */
+	if (unlikely(list_empty_careful(&bdi->wb_list)))
+		wake_up_process(default_backing_dev_info.wb.task);
+	else {
+		struct bdi_writeback *wb = &bdi->wb;
 
-		/*
-		 * Only add valid (hashed) inodes to the superblock's
-		 * dirty list.  Add blockdev inodes as well.
-		 */
-		if (!S_ISBLK(inode->i_mode)) {
-			if (hlist_unhashed(&inode->i_hash))
-				goto out;
-		}
-		if (inode->i_state & (I_FREEING|I_CLEAR))
-			goto out;
+		if (wb->task)
+			wake_up_process(wb->task);
+	}
+}
 
-		/*
-		 * If the inode was already on s_dirty/s_io/s_more_io, don't
-		 * reposition it (that would break s_dirty time-ordering).
-		 */
-		if (!was_dirty) {
-			inode->dirtied_when = jiffies;
-			list_move(&inode->i_list, &sb->s_dirty);
-		}
+/*
+ * Used for on-stack allocated work items. The caller needs to wait until
+ * the wb threads have acked the work before it's safe to continue.
+ */
+static void bdi_wait_on_work_clear(struct bdi_work *work)
+{
+	wait_on_bit(&work->state, WS_USED_B, bdi_sched_wait,
+		    TASK_UNINTERRUPTIBLE);
+}
+
+static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
+				 struct wb_writeback_args *args)
+{
+	struct bdi_work *work;
+
+	/*
+	 * This is WB_SYNC_NONE writeback, so if allocation fails just
+	 * wakeup the thread for old dirty data writeback
+	 */
+	work = kmalloc(sizeof(*work), GFP_ATOMIC);
+	if (work) {
+		bdi_work_init(work, args);
+		bdi_queue_work(bdi, work);
+	} else {
+		struct bdi_writeback *wb = &bdi->wb;
+
+		if (wb->task)
+			wake_up_process(wb->task);
 	}
-out:
-	spin_unlock(&inode_lock);
 }
 
-EXPORT_SYMBOL(__mark_inode_dirty);
+/**
+ * bdi_sync_writeback - start and wait for writeback
+ * @bdi: the backing device to write from
+ * @sb: write inodes from this super_block
+ *
+ * Description:
+ *   This does WB_SYNC_ALL data integrity writeback and waits for the
+ *   IO to complete. Callers must hold the sb s_umount semaphore for
+ *   reading, to avoid having the super disappear before we are done.
+ */
+static void bdi_sync_writeback(struct backing_dev_info *bdi,
+			       struct super_block *sb)
+{
+	struct wb_writeback_args args = {
+		.sb		= sb,
+		.sync_mode	= WB_SYNC_ALL,
+		.nr_pages	= LONG_MAX,
+		.range_cyclic	= 0,
+	};
+	struct bdi_work work;
 
-static int write_inode(struct inode *inode, int sync)
+	bdi_work_init(&work, &args);
+	work.state |= WS_ONSTACK;
+
+	bdi_queue_work(bdi, &work);
+	bdi_wait_on_work_clear(&work);
+}
+
+/**
+ * bdi_start_writeback - start writeback
+ * @bdi: the backing device to write from
+ * @nr_pages: the number of pages to write
+ *
+ * Description:
+ *   This does WB_SYNC_NONE opportunistic writeback. The IO is only
+ *   started when this function returns, we make no guarentees on
+ *   completion. Caller need not hold sb s_umount semaphore.
+ *
+ */
+void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
+			 long nr_pages)
 {
-	if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode))
-		return inode->i_sb->s_op->write_inode(inode, sync);
-	return 0;
+	struct wb_writeback_args args = {
+		.sb		= sb,
+		.sync_mode	= WB_SYNC_NONE,
+		.nr_pages	= nr_pages,
+		.range_cyclic	= 1,
+	};
+
+	/*
+	 * We treat @nr_pages=0 as the special case to do background writeback,
+	 * ie. to sync pages until the background dirty threshold is reached.
+	 */
+	if (!nr_pages) {
+		args.nr_pages = LONG_MAX;
+		args.for_background = 1;
+	}
+
+	bdi_alloc_queue_work(bdi, &args);
 }
 
 /*
@@ -191,31 +277,32 @@ static int write_inode(struct inode *inode, int sync)
  * furthest end of its superblock's dirty-inode list.
  *
  * Before stamping the inode's ->dirtied_when, we check to see whether it is
- * already the most-recently-dirtied inode on the s_dirty list.  If that is
+ * already the most-recently-dirtied inode on the b_dirty list.  If that is
  * the case then the inode must have been redirtied while it was being written
  * out and we don't reset its dirtied_when.
  */
 static void redirty_tail(struct inode *inode)
 {
-	struct super_block *sb = inode->i_sb;
+	struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
 
-	if (!list_empty(&sb->s_dirty)) {
-		struct inode *tail_inode;
+	if (!list_empty(&wb->b_dirty)) {
+		struct inode *tail;
 
-		tail_inode = list_entry(sb->s_dirty.next, struct inode, i_list);
-		if (time_before(inode->dirtied_when,
-				tail_inode->dirtied_when))
+		tail = list_entry(wb->b_dirty.next, struct inode, i_list);
+		if (time_before(inode->dirtied_when, tail->dirtied_when))
 			inode->dirtied_when = jiffies;
 	}
-	list_move(&inode->i_list, &sb->s_dirty);
+	list_move(&inode->i_list, &wb->b_dirty);
 }
 
 /*
- * requeue inode for re-scanning after sb->s_io list is exhausted.
+ * requeue inode for re-scanning after bdi->b_io list is exhausted.
  */
 static void requeue_io(struct inode *inode)
 {
-	list_move(&inode->i_list, &inode->i_sb->s_more_io);
+	struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
+
+	list_move(&inode->i_list, &wb->b_more_io);
 }
 
 static void inode_sync_complete(struct inode *inode)
@@ -235,7 +322,7 @@ static bool inode_dirtied_after(struct inode *inode, unsigned long t)
 	 * For inodes being constantly redirtied, dirtied_when can get stuck.
 	 * It _appears_ to be in the future, but is actually in distant past.
 	 * This test is necessary to prevent such wrapped-around relative times
-	 * from permanently stopping the whole pdflush writeback.
+	 * from permanently stopping the whole bdi writeback.
 	 */
 	ret = ret && time_before_eq(inode->dirtied_when, jiffies);
 #endif
@@ -249,33 +336,56 @@ static void move_expired_inodes(struct list_head *delaying_queue,
 			       struct list_head *dispatch_queue,
 				unsigned long *older_than_this)
 {
+	LIST_HEAD(tmp);
+	struct list_head *pos, *node;
+	struct super_block *sb = NULL;
+	struct inode *inode;
+	int do_sb_sort = 0;
+
 	while (!list_empty(delaying_queue)) {
-		struct inode *inode = list_entry(delaying_queue->prev,
-						struct inode, i_list);
+		inode = list_entry(delaying_queue->prev, struct inode, i_list);
 		if (older_than_this &&
 		    inode_dirtied_after(inode, *older_than_this))
 			break;
-		list_move(&inode->i_list, dispatch_queue);
+		if (sb && sb != inode->i_sb)
+			do_sb_sort = 1;
+		sb = inode->i_sb;
+		list_move(&inode->i_list, &tmp);
+	}
+
+	/* just one sb in list, splice to dispatch_queue and we're done */
+	if (!do_sb_sort) {
+		list_splice(&tmp, dispatch_queue);
+		return;
+	}
+
+	/* Move inodes from one superblock together */
+	while (!list_empty(&tmp)) {
+		inode = list_entry(tmp.prev, struct inode, i_list);
+		sb = inode->i_sb;
+		list_for_each_prev_safe(pos, node, &tmp) {
+			inode = list_entry(pos, struct inode, i_list);
+			if (inode->i_sb == sb)
+				list_move(&inode->i_list, dispatch_queue);
+		}
 	}
 }
 
 /*
  * Queue all expired dirty inodes for io, eldest first.
  */
-static void queue_io(struct super_block *sb,
-				unsigned long *older_than_this)
+static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
 {
-	list_splice_init(&sb->s_more_io, sb->s_io.prev);
-	move_expired_inodes(&sb->s_dirty, &sb->s_io, older_than_this);
+	list_splice_init(&wb->b_more_io, wb->b_io.prev);
+	move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this);
 }
 
-int sb_has_dirty_inodes(struct super_block *sb)
+static int write_inode(struct inode *inode, int sync)
 {
-	return !list_empty(&sb->s_dirty) ||
-	       !list_empty(&sb->s_io) ||
-	       !list_empty(&sb->s_more_io);
+	if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode))
+		return inode->i_sb->s_op->write_inode(inode, sync);
+	return 0;
 }
-EXPORT_SYMBOL(sb_has_dirty_inodes);
 
 /*
  * Wait for writeback on an inode to complete.
@@ -322,11 +432,11 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 	if (inode->i_state & I_SYNC) {
 		/*
 		 * If this inode is locked for writeback and we are not doing
-		 * writeback-for-data-integrity, move it to s_more_io so that
+		 * writeback-for-data-integrity, move it to b_more_io so that
 		 * writeback can proceed with the other inodes on s_io.
 		 *
 		 * We'll have another go at writing back this inode when we
-		 * completed a full scan of s_io.
+		 * completed a full scan of b_io.
 		 */
 		if (!wait) {
 			requeue_io(inode);
@@ -366,16 +476,26 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 	spin_lock(&inode_lock);
 	inode->i_state &= ~I_SYNC;
 	if (!(inode->i_state & (I_FREEING | I_CLEAR))) {
-		if (!(inode->i_state & I_DIRTY) &&
-		    mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
+		if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) {
+			/*
+			 * More pages get dirtied by a fast dirtier.
+			 */
+			goto select_queue;
+		} else if (inode->i_state & I_DIRTY) {
+			/*
+			 * At least XFS will redirty the inode during the
+			 * writeback (delalloc) and on io completion (isize).
+			 */
+			redirty_tail(inode);
+		} else if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
 			/*
 			 * We didn't write back all the pages.  nfs_writepages()
 			 * sometimes bales out without doing anything. Redirty
-			 * the inode; Move it from s_io onto s_more_io/s_dirty.
+			 * the inode; Move it from b_io onto b_more_io/b_dirty.
 			 */
 			/*
 			 * akpm: if the caller was the kupdate function we put
-			 * this inode at the head of s_dirty so it gets first
+			 * this inode at the head of b_dirty so it gets first
 			 * consideration.  Otherwise, move it to the tail, for
 			 * the reasons described there.  I'm not really sure
 			 * how much sense this makes.  Presumably I had a good
@@ -385,10 +505,11 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 			if (wbc->for_kupdate) {
 				/*
 				 * For the kupdate function we move the inode
-				 * to s_more_io so it will get more writeout as
+				 * to b_more_io so it will get more writeout as
 				 * soon as the queue becomes uncongested.
 				 */
 				inode->i_state |= I_DIRTY_PAGES;
+select_queue:
 				if (wbc->nr_to_write <= 0) {
 					/*
 					 * slice used up: queue for next turn
@@ -411,12 +532,6 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 				inode->i_state |= I_DIRTY_PAGES;
 				redirty_tail(inode);
 			}
-		} else if (inode->i_state & I_DIRTY) {
-			/*
-			 * Someone redirtied the inode while were writing back
-			 * the pages.
-			 */
-			redirty_tail(inode);
 		} else if (atomic_read(&inode->i_count)) {
 			/*
 			 * The inode is clean, inuse
@@ -433,51 +548,96 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 	return ret;
 }
 
+static void unpin_sb_for_writeback(struct super_block **psb)
+{
+	struct super_block *sb = *psb;
+
+	if (sb) {
+		up_read(&sb->s_umount);
+		put_super(sb);
+		*psb = NULL;
+	}
+}
+
 /*
- * Write out a superblock's list of dirty inodes.  A wait will be performed
- * upon no inodes, all inodes or the final one, depending upon sync_mode.
- *
- * If older_than_this is non-NULL, then only write out inodes which
- * had their first dirtying at a time earlier than *older_than_this.
- *
- * If we're a pdflush thread, then implement pdflush collision avoidance
- * against the entire list.
- *
- * If `bdi' is non-zero then we're being asked to writeback a specific queue.
- * This function assumes that the blockdev superblock's inodes are backed by
- * a variety of queues, so all inodes are searched.  For other superblocks,
- * assume that all inodes are backed by the same queue.
+ * For WB_SYNC_NONE writeback, the caller does not have the sb pinned
+ * before calling writeback. So make sure that we do pin it, so it doesn't
+ * go away while we are writing inodes from it.
  *
- * FIXME: this linear search could get expensive with many fileystems.  But
- * how to fix?  We need to go from an address_space to all inodes which share
- * a queue with that address_space.  (Easy: have a global "dirty superblocks"
- * list).
- *
- * The inodes to be written are parked on sb->s_io.  They are moved back onto
- * sb->s_dirty as they are selected for writing.  This way, none can be missed
- * on the writer throttling path, and we get decent balancing between many
- * throttled threads: we don't want them all piling up on inode_sync_wait.
+ * Returns 0 if the super was successfully pinned (or pinning wasn't needed),
+ * 1 if we failed.
  */
-void generic_sync_sb_inodes(struct super_block *sb,
+static int pin_sb_for_writeback(struct writeback_control *wbc,
+				struct inode *inode, struct super_block **psb)
+{
+	struct super_block *sb = inode->i_sb;
+
+	/*
+	 * If this sb is already pinned, nothing more to do. If not and
+	 * *psb is non-NULL, unpin the old one first
+	 */
+	if (sb == *psb)
+		return 0;
+	else if (*psb)
+		unpin_sb_for_writeback(psb);
+
+	/*
+	 * Caller must already hold the ref for this
+	 */
+	if (wbc->sync_mode == WB_SYNC_ALL) {
+		WARN_ON(!rwsem_is_locked(&sb->s_umount));
+		return 0;
+	}
+
+	spin_lock(&sb_lock);
+	sb->s_count++;
+	if (down_read_trylock(&sb->s_umount)) {
+		if (sb->s_root) {
+			spin_unlock(&sb_lock);
+			goto pinned;
+		}
+		/*
+		 * umounted, drop rwsem again and fall through to failure
+		 */
+		up_read(&sb->s_umount);
+	}
+
+	sb->s_count--;
+	spin_unlock(&sb_lock);
+	return 1;
+pinned:
+	*psb = sb;
+	return 0;
+}
+
+static void writeback_inodes_wb(struct bdi_writeback *wb,
 				struct writeback_control *wbc)
 {
+	struct super_block *sb = wbc->sb, *pin_sb = NULL;
+	const int is_blkdev_sb = sb_is_blkdev_sb(sb);
 	const unsigned long start = jiffies;	/* livelock avoidance */
-	int sync = wbc->sync_mode == WB_SYNC_ALL;
 
 	spin_lock(&inode_lock);
-	if (!wbc->for_kupdate || list_empty(&sb->s_io))
-		queue_io(sb, wbc->older_than_this);
 
-	while (!list_empty(&sb->s_io)) {
-		struct inode *inode = list_entry(sb->s_io.prev,
+	if (!wbc->for_kupdate || list_empty(&wb->b_io))
+		queue_io(wb, wbc->older_than_this);
+
+	while (!list_empty(&wb->b_io)) {
+		struct inode *inode = list_entry(wb->b_io.prev,
 						struct inode, i_list);
-		struct address_space *mapping = inode->i_mapping;
-		struct backing_dev_info *bdi = mapping->backing_dev_info;
 		long pages_skipped;
 
-		if (!bdi_cap_writeback_dirty(bdi)) {
+		/*
+		 * super block given and doesn't match, skip this inode
+		 */
+		if (sb && sb != inode->i_sb) {
 			redirty_tail(inode);
-			if (sb_is_blkdev_sb(sb)) {
+			continue;
+		}
+
+		if (!bdi_cap_writeback_dirty(wb->bdi)) {
+			redirty_tail(inode);
+			if (is_blkdev_sb) {
 				/*
 				 * Dirty memory-backed blockdev: the ramdisk
 				 * driver does this.  Skip just this inode
@@ -497,21 +657,14 @@ void generic_sync_sb_inodes(struct super_block *sb,
 			continue;
 		}
 
-		if (wbc->nonblocking && bdi_write_congested(bdi)) {
+		if (wbc->nonblocking && bdi_write_congested(wb->bdi)) {
 			wbc->encountered_congestion = 1;
-			if (!sb_is_blkdev_sb(sb))
+			if (!is_blkdev_sb)
 				break;		/* Skip a congested fs */
 			requeue_io(inode);
 			continue;		/* Skip a congested blockdev */
 		}
 
-		if (wbc->bdi && bdi != wbc->bdi) {
-			if (!sb_is_blkdev_sb(sb))
-				break;		/* fs has the wrong queue */
-			requeue_io(inode);
-			continue;		/* blockdev has wrong queue */
-		}
-
 		/*
 		 * Was this inode dirtied after sync_sb_inodes was called?
 		 * This keeps sync from extra jobs and livelock.
@@ -519,16 +672,15 @@ void generic_sync_sb_inodes(struct super_block *sb,
 		if (inode_dirtied_after(inode, start))
 			break;
 
-		/* Is another pdflush already flushing this queue? */
-		if (current_is_pdflush() && !writeback_acquire(bdi))
-			break;
+		if (pin_sb_for_writeback(wbc, inode, &pin_sb)) {
+			requeue_io(inode);
+			continue;
+		}
 
 		BUG_ON(inode->i_state & (I_FREEING | I_CLEAR));
 		__iget(inode);
 		pages_skipped = wbc->pages_skipped;
 		writeback_single_inode(inode, wbc);
-		if (current_is_pdflush())
-			writeback_release(bdi);
 		if (wbc->pages_skipped != pages_skipped) {
 			/*
 			 * writeback is not making progress due to locked
@@ -544,144 +696,535 @@ void generic_sync_sb_inodes(struct super_block *sb,
 			wbc->more_io = 1;
 			break;
 		}
-		if (!list_empty(&sb->s_more_io))
+		if (!list_empty(&wb->b_more_io))
 			wbc->more_io = 1;
 	}
 
-	if (sync) {
-		struct inode *inode, *old_inode = NULL;
+	unpin_sb_for_writeback(&pin_sb);
 
+	spin_unlock(&inode_lock);
+	/* Leave any unwritten inodes on b_io */
+}
+
+void writeback_inodes_wbc(struct writeback_control *wbc)
+{
+	struct backing_dev_info *bdi = wbc->bdi;
+
+	writeback_inodes_wb(&bdi->wb, wbc);
+}
+
+/*
+ * The maximum number of pages to writeout in a single bdi flush/kupdate
+ * operation.  We do this so we don't hold I_SYNC against an inode for
+ * enormous amounts of time, which would block a userspace task which has
+ * been forced to throttle against that inode.  Also, the code reevaluates
+ * the dirty each time it has written this many pages.
+ */
+#define MAX_WRITEBACK_PAGES     1024
+
+static inline bool over_bground_thresh(void)
+{
+	unsigned long background_thresh, dirty_thresh;
+
+	get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
+
+	return (global_page_state(NR_FILE_DIRTY) +
+		global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
+}
+
+/*
+ * Explicit flushing or periodic writeback of "old" data.
+ *
+ * Define "old": the first time one of an inode's pages is dirtied, we mark the
+ * dirtying-time in the inode's address_space.  So this periodic writeback code
+ * just walks the superblock inode list, writing back any inodes which are
+ * older than a specific point in time.
+ *
+ * Try to run once per dirty_writeback_interval.  But if a writeback event
+ * takes longer than a dirty_writeback_interval interval, then leave a
+ * one-second gap.
+ *
+ * older_than_this takes precedence over nr_to_write.  So we'll only write back
+ * all dirty pages if they are all attached to "old" mappings.
+ */
+static long wb_writeback(struct bdi_writeback *wb,
+			 struct wb_writeback_args *args)
+{
+	struct writeback_control wbc = {
+		.bdi			= wb->bdi,
+		.sb			= args->sb,
+		.sync_mode		= args->sync_mode,
+		.older_than_this	= NULL,
+		.for_kupdate		= args->for_kupdate,
+		.range_cyclic		= args->range_cyclic,
+	};
+	unsigned long oldest_jif;
+	long wrote = 0;
+	struct inode *inode;
+
+	if (wbc.for_kupdate) {
+		wbc.older_than_this = &oldest_jif;
+		oldest_jif = jiffies -
+				msecs_to_jiffies(dirty_expire_interval * 10);
+	}
+	if (!wbc.range_cyclic) {
+		wbc.range_start = 0;
+		wbc.range_end = LLONG_MAX;
+	}
+
+	for (;;) {
 		/*
-		 * Data integrity sync. Must wait for all pages under writeback,
-		 * because there may have been pages dirtied before our sync
-		 * call, but which had writeout started before we write it out.
-		 * In which case, the inode may not be on the dirty list, but
-		 * we still have to wait for that writeout.
+		 * Stop writeback when nr_pages has been consumed
 		 */
-		list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
-			struct address_space *mapping;
-
-			if (inode->i_state &
-					(I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
-				continue;
-			mapping = inode->i_mapping;
-			if (mapping->nrpages == 0)
-				continue;
-			__iget(inode);
-			spin_unlock(&inode_lock);
-			/*
-			 * We hold a reference to 'inode' so it couldn't have
-			 * been removed from s_inodes list while we dropped the
-			 * inode_lock.  We cannot iput the inode now as we can
-			 * be holding the last reference and we cannot iput it
-			 * under inode_lock. So we keep the reference and iput
-			 * it later.
-			 */
-			iput(old_inode);
-			old_inode = inode;
+		if (args->nr_pages <= 0)
+			break;
 
-			filemap_fdatawait(mapping);
+		/*
+		 * For background writeout, stop when we are below the
+		 * background dirty threshold
+		 */
+		if (args->for_background && !over_bground_thresh())
+			break;
 
-			cond_resched();
+		wbc.more_io = 0;
+		wbc.encountered_congestion = 0;
+		wbc.nr_to_write = MAX_WRITEBACK_PAGES;
+		wbc.pages_skipped = 0;
+		writeback_inodes_wb(wb, &wbc);
+		args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
+		wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
 
-			spin_lock(&inode_lock);
+		/*
+		 * If we consumed everything, see if we have more
+		 */
+		if (wbc.nr_to_write <= 0)
+			continue;
+		/*
+		 * Didn't write everything and we don't have more IO, bail
+		 */
+		if (!wbc.more_io)
+			break;
+		/*
+		 * Did we write something? Try for more
+		 */
+		if (wbc.nr_to_write < MAX_WRITEBACK_PAGES)
+			continue;
+		/*
+		 * Nothing written. Wait for some inode to
+		 * become available for writeback. Otherwise
+		 * we'll just busyloop.
+		 */
+		spin_lock(&inode_lock);
+		if (!list_empty(&wb->b_more_io))  {
+			inode = list_entry(wb->b_more_io.prev,
+						struct inode, i_list);
+			inode_wait_for_writeback(inode);
 		}
 		spin_unlock(&inode_lock);
-		iput(old_inode);
-	} else
-		spin_unlock(&inode_lock);
+	}
 
-	return;		/* Leave any unwritten inodes on s_io */
+	return wrote;
 }
-EXPORT_SYMBOL_GPL(generic_sync_sb_inodes);
 
-static void sync_sb_inodes(struct super_block *sb,
-				struct writeback_control *wbc)
+/*
+ * Return the next bdi_work struct that hasn't been processed by this
+ * wb thread yet. ->seen is initially set for each thread that exists
+ * for this device, when a thread first notices a piece of work it
+ * clears its bit. Depending on writeback type, the thread will notify
+ * completion on either receiving the work (WB_SYNC_NONE) or after
+ * it is done (WB_SYNC_ALL).
+ */
+static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
+					   struct bdi_writeback *wb)
+{
+	struct bdi_work *work, *ret = NULL;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(work, &bdi->work_list, list) {
+		if (!test_bit(wb->nr, &work->seen))
+			continue;
+		clear_bit(wb->nr, &work->seen);
+
+		ret = work;
+		break;
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+
+static long wb_check_old_data_flush(struct bdi_writeback *wb)
+{
+	unsigned long expired;
+	long nr_pages;
+
+	expired = wb->last_old_flush +
+			msecs_to_jiffies(dirty_writeback_interval * 10);
+	if (time_before(jiffies, expired))
+		return 0;
+
+	wb->last_old_flush = jiffies;
+	nr_pages = global_page_state(NR_FILE_DIRTY) +
+			global_page_state(NR_UNSTABLE_NFS) +
+			(inodes_stat.nr_inodes - inodes_stat.nr_unused);
+
+	if (nr_pages) {
+		struct wb_writeback_args args = {
+			.nr_pages	= nr_pages,
+			.sync_mode	= WB_SYNC_NONE,
+			.for_kupdate	= 1,
+			.range_cyclic	= 1,
+		};
+
+		return wb_writeback(wb, &args);
+	}
+
+	return 0;
+}
+
+/*
+ * Retrieve work items and do the writeback they describe
+ */
+long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
+{
+	struct backing_dev_info *bdi = wb->bdi;
+	struct bdi_work *work;
+	long wrote = 0;
+
+	while ((work = get_next_work_item(bdi, wb)) != NULL) {
+		struct wb_writeback_args args = work->args;
+
+		/*
+		 * Override sync mode, in case we must wait for completion
+		 */
+		if (force_wait)
+			work->args.sync_mode = args.sync_mode = WB_SYNC_ALL;
+
+		/*
+		 * If this isn't a data integrity operation, just notify
+		 * that we have seen this work and we are now starting it.
+		 */
+		if (args.sync_mode == WB_SYNC_NONE)
+			wb_clear_pending(wb, work);
+
+		wrote += wb_writeback(wb, &args);
+
+		/*
+		 * This is a data integrity writeback, so only do the
+		 * notification when we have completed the work.
+		 */
+		if (args.sync_mode == WB_SYNC_ALL)
+			wb_clear_pending(wb, work);
+	}
+
+	/*
+	 * Check for periodic writeback, kupdated() style
+	 */
+	wrote += wb_check_old_data_flush(wb);
+
+	return wrote;
+}
+
+/*
+ * Handle writeback of dirty data for the device backed by this bdi. Also
+ * wakes up periodically and does kupdated style flushing.
+ */
+int bdi_writeback_task(struct bdi_writeback *wb)
+{
+	unsigned long last_active = jiffies;
+	unsigned long wait_jiffies = -1UL;
+	long pages_written;
+
+	while (!kthread_should_stop()) {
+		pages_written = wb_do_writeback(wb, 0);
+
+		if (pages_written)
+			last_active = jiffies;
+		else if (wait_jiffies != -1UL) {
+			unsigned long max_idle;
+
+			/*
+			 * Longest period of inactivity that we tolerate. If we
+			 * see dirty data again later, the task will get
+			 * recreated automatically.
+			 */
+			max_idle = max(5UL * 60 * HZ, wait_jiffies);
+			if (time_after(jiffies, max_idle + last_active))
+				break;
+		}
+
+		wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
+		schedule_timeout_interruptible(wait_jiffies);
+		try_to_freeze();
+	}
+
+	return 0;
+}
+
+/*
+ * Schedule writeback for all backing devices. This does WB_SYNC_NONE
+ * writeback, for integrity writeback see bdi_sync_writeback().
+ */
+static void bdi_writeback_all(struct super_block *sb, long nr_pages)
 {
-	generic_sync_sb_inodes(sb, wbc);
+	struct wb_writeback_args args = {
+		.sb		= sb,
+		.nr_pages	= nr_pages,
+		.sync_mode	= WB_SYNC_NONE,
+	};
+	struct backing_dev_info *bdi;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
+		if (!bdi_has_dirty_io(bdi))
+			continue;
+
+		bdi_alloc_queue_work(bdi, &args);
+	}
+
+	rcu_read_unlock();
 }
 
 /*
- * Start writeback of dirty pagecache data against all unlocked inodes.
+ * Start writeback of `nr_pages' pages.  If `nr_pages' is zero, write back
+ * the whole world.
+ */
+void wakeup_flusher_threads(long nr_pages)
+{
+	if (nr_pages == 0)
+		nr_pages = global_page_state(NR_FILE_DIRTY) +
+				global_page_state(NR_UNSTABLE_NFS);
+	bdi_writeback_all(NULL, nr_pages);
+}
+
+static noinline void block_dump___mark_inode_dirty(struct inode *inode)
+{
+	if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) {
+		struct dentry *dentry;
+		const char *name = "?";
+
+		dentry = d_find_alias(inode);
+		if (dentry) {
+			spin_lock(&dentry->d_lock);
+			name = (const char *) dentry->d_name.name;
+		}
+		printk(KERN_DEBUG
+		       "%s(%d): dirtied inode %lu (%s) on %s\n",
+		       current->comm, task_pid_nr(current), inode->i_ino,
+		       name, inode->i_sb->s_id);
+		if (dentry) {
+			spin_unlock(&dentry->d_lock);
+			dput(dentry);
+		}
+	}
+}
+
+/**
+ *	__mark_inode_dirty -	internal function
+ *	@inode: inode to mark
+ *	@flags: what kind of dirty (i.e. I_DIRTY_SYNC)
+ *	Mark an inode as dirty. Callers should use mark_inode_dirty or
+ *  	mark_inode_dirty_sync.
+ *
+ * Put the inode on the super block's dirty list.
+ *
+ * CAREFUL! We mark it dirty unconditionally, but move it onto the
+ * dirty list only if it is hashed or if it refers to a blockdev.
+ * If it was not hashed, it will never be added to the dirty list
+ * even if it is later hashed, as it will have been marked dirty already.
  *
- * Note:
- * We don't need to grab a reference to superblock here. If it has non-empty
- * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed
- * past sync_inodes_sb() until the ->s_dirty/s_io/s_more_io lists are all
- * empty. Since __sync_single_inode() regains inode_lock before it finally moves
- * inode from superblock lists we are OK.
+ * In short, make sure you hash any inodes _before_ you start marking
+ * them dirty.
  *
- * If `older_than_this' is non-zero then only flush inodes which have a
- * flushtime older than *older_than_this.
+ * This function *must* be atomic for the I_DIRTY_PAGES case -
+ * set_page_dirty() is called under spinlock in several places.
  *
- * If `bdi' is non-zero then we will scan the first inode against each
- * superblock until we find the matching ones.  One group will be the dirty
- * inodes against a filesystem.  Then when we hit the dummy blockdev superblock,
- * sync_sb_inodes will seekout the blockdev which matches `bdi'.  Maybe not
- * super-efficient but we're about to do a ton of I/O...
+ * Note that for blockdevs, inode->dirtied_when represents the dirtying time of
+ * the block-special inode (/dev/hda1) itself.  And the ->dirtied_when field of
+ * the kernel-internal blockdev inode represents the dirtying time of the
+ * blockdev's pages.  This is why for I_DIRTY_PAGES we always use
+ * page->mapping->host, so the page-dirtying time is recorded in the internal
+ * blockdev inode.
  */
-void
-writeback_inodes(struct writeback_control *wbc)
+void __mark_inode_dirty(struct inode *inode, int flags)
 {
-	struct super_block *sb;
+	struct super_block *sb = inode->i_sb;
 
-	might_sleep();
-	spin_lock(&sb_lock);
-restart:
-	list_for_each_entry_reverse(sb, &super_blocks, s_list) {
-		if (sb_has_dirty_inodes(sb)) {
-			/* we're making our own get_super here */
-			sb->s_count++;
-			spin_unlock(&sb_lock);
-			/*
-			 * If we can't get the readlock, there's no sense in
-			 * waiting around, most of the time the FS is going to
-			 * be unmounted by the time it is released.
-			 */
-			if (down_read_trylock(&sb->s_umount)) {
-				if (sb->s_root)
-					sync_sb_inodes(sb, wbc);
-				up_read(&sb->s_umount);
+	/*
+	 * Don't do this for I_DIRTY_PAGES - that doesn't actually
+	 * dirty the inode itself
+	 */
+	if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
+		if (sb->s_op->dirty_inode)
+			sb->s_op->dirty_inode(inode);
+	}
+
+	/*
+	 * make sure that changes are seen by all cpus before we test i_state
+	 * -- mikulas
+	 */
+	smp_mb();
+
+	/* avoid the locking if we can */
+	if ((inode->i_state & flags) == flags)
+		return;
+
+	if (unlikely(block_dump))
+		block_dump___mark_inode_dirty(inode);
+
+	spin_lock(&inode_lock);
+	if ((inode->i_state & flags) != flags) {
+		const int was_dirty = inode->i_state & I_DIRTY;
+
+		inode->i_state |= flags;
+
+		/*
+		 * If the inode is being synced, just update its dirty state.
+		 * The unlocker will place the inode on the appropriate
+		 * superblock list, based upon its state.
+		 */
+		if (inode->i_state & I_SYNC)
+			goto out;
+
+		/*
+		 * Only add valid (hashed) inodes to the superblock's
+		 * dirty list.  Add blockdev inodes as well.
+		 */
+		if (!S_ISBLK(inode->i_mode)) {
+			if (hlist_unhashed(&inode->i_hash))
+				goto out;
+		}
+		if (inode->i_state & (I_FREEING|I_CLEAR))
+			goto out;
+
+		/*
+		 * If the inode was already on b_dirty/b_io/b_more_io, don't
+		 * reposition it (that would break b_dirty time-ordering).
+		 */
+		if (!was_dirty) {
+			struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
+			struct backing_dev_info *bdi = wb->bdi;
+
+			if (bdi_cap_writeback_dirty(bdi) &&
+			    !test_bit(BDI_registered, &bdi->state)) {
+				WARN_ON(1);
+				printk(KERN_ERR "bdi-%s not registered\n",
+								bdi->name);
 			}
-			spin_lock(&sb_lock);
-			if (__put_super_and_need_restart(sb))
-				goto restart;
+
+			inode->dirtied_when = jiffies;
+			list_move(&inode->i_list, &wb->b_dirty);
 		}
-		if (wbc->nr_to_write <= 0)
-			break;
 	}
-	spin_unlock(&sb_lock);
+out:
+	spin_unlock(&inode_lock);
 }
+EXPORT_SYMBOL(__mark_inode_dirty);
 
 /*
- * writeback and wait upon the filesystem's dirty inodes.  The caller will
- * do this in two passes - one to write, and one to wait.
+ * Write out a superblock's list of dirty inodes.  A wait will be performed
+ * upon no inodes, all inodes or the final one, depending upon sync_mode.
+ *
+ * If older_than_this is non-NULL, then only write out inodes which
+ * had their first dirtying at a time earlier than *older_than_this.
  *
- * A finite limit is set on the number of pages which will be written.
- * To prevent infinite livelock of sys_sync().
+ * If `bdi' is non-zero then we're being asked to writeback a specific queue.
+ * This function assumes that the blockdev superblock's inodes are backed by
+ * a variety of queues, so all inodes are searched.  For other superblocks,
+ * assume that all inodes are backed by the same queue.
  *
- * We add in the number of potentially dirty inodes, because each inode write
- * can dirty pagecache in the underlying blockdev.
+ * The inodes to be written are parked on bdi->b_io.  They are moved back onto
+ * bdi->b_dirty as they are selected for writing.  This way, none can be missed
+ * on the writer throttling path, and we get decent balancing between many
+ * throttled threads: we don't want them all piling up on inode_sync_wait.
  */
-void sync_inodes_sb(struct super_block *sb, int wait)
+static void wait_sb_inodes(struct super_block *sb)
 {
-	struct writeback_control wbc = {
-		.sync_mode	= wait ? WB_SYNC_ALL : WB_SYNC_NONE,
-		.range_start	= 0,
-		.range_end	= LLONG_MAX,
-	};
+	struct inode *inode, *old_inode = NULL;
+
+	/*
+	 * We need to be protected against the filesystem going from
+	 * r/o to r/w or vice versa.
+	 */
+	WARN_ON(!rwsem_is_locked(&sb->s_umount));
+
+	spin_lock(&inode_lock);
 
-	if (!wait) {
-		unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
-		unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
+	/*
+	 * Data integrity sync. Must wait for all pages under writeback,
+	 * because there may have been pages dirtied before our sync
+	 * call, but which had writeout started before we write it out.
+	 * In which case, the inode may not be on the dirty list, but
+	 * we still have to wait for that writeout.
+	 */
+	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+		struct address_space *mapping;
 
-		wbc.nr_to_write = nr_dirty + nr_unstable +
+		if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW))
+			continue;
+		mapping = inode->i_mapping;
+		if (mapping->nrpages == 0)
+			continue;
+		__iget(inode);
+		spin_unlock(&inode_lock);
+		/*
+		 * We hold a reference to 'inode' so it couldn't have
+		 * been removed from s_inodes list while we dropped the
+		 * inode_lock.  We cannot iput the inode now as we can
+		 * be holding the last reference and we cannot iput it
+		 * under inode_lock. So we keep the reference and iput
+		 * it later.
+		 */
+		iput(old_inode);
+		old_inode = inode;
+
+		filemap_fdatawait(mapping);
+
+		cond_resched();
+
+		spin_lock(&inode_lock);
+	}
+	spin_unlock(&inode_lock);
+	iput(old_inode);
+}
+
+/**
+ * writeback_inodes_sb	-	writeback dirty inodes from given super_block
+ * @sb: the superblock
+ *
+ * Start writeback on some inodes on this super_block. No guarantees are made
+ * on how many (if any) will be written, and this function does not wait
+ * for IO completion of submitted IO. The number of pages submitted is
+ * returned.
+ */
+void writeback_inodes_sb(struct super_block *sb)
+{
+	unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
+	unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
+	long nr_to_write;
+
+	nr_to_write = nr_dirty + nr_unstable +
 			(inodes_stat.nr_inodes - inodes_stat.nr_unused);
-	} else
-		wbc.nr_to_write = LONG_MAX; /* doesn't actually matter */
 
-	sync_sb_inodes(sb, &wbc);
+	bdi_start_writeback(sb->s_bdi, sb, nr_to_write);
 }
+EXPORT_SYMBOL(writeback_inodes_sb);
+
+/**
+ * sync_inodes_sb	-	sync sb inode pages
+ * @sb: the superblock
+ *
+ * This function writes and waits on any dirty inode belonging to this
+ * super_block. The number of pages synced is returned.
+ */
+void sync_inodes_sb(struct super_block *sb)
+{
+	bdi_sync_writeback(sb->s_bdi, sb);
+	wait_sb_inodes(sb);
+}
+EXPORT_SYMBOL(sync_inodes_sb);
 
 /**
  * write_inode_now	-	write an inode to disk
@@ -737,57 +1280,3 @@ int sync_inode(struct inode *inode, struct writeback_control *wbc)
 	return ret;
 }
 EXPORT_SYMBOL(sync_inode);
-
-/**
- * generic_osync_inode - flush all dirty data for a given inode to disk
- * @inode: inode to write
- * @mapping: the address_space that should be flushed
- * @what:  what to write and wait upon
- *
- * This can be called by file_write functions for files which have the
- * O_SYNC flag set, to flush dirty writes to disk.
- *
- * @what is a bitmask, specifying which part of the inode's data should be
- * written and waited upon.
- *
- *    OSYNC_DATA:     i_mapping's dirty data
- *    OSYNC_METADATA: the buffers at i_mapping->private_list
- *    OSYNC_INODE:    the inode itself
- */
-
-int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what)
-{
-	int err = 0;
-	int need_write_inode_now = 0;
-	int err2;
-
-	if (what & OSYNC_DATA)
-		err = filemap_fdatawrite(mapping);
-	if (what & (OSYNC_METADATA|OSYNC_DATA)) {
-		err2 = sync_mapping_buffers(mapping);
-		if (!err)
-			err = err2;
-	}
-	if (what & OSYNC_DATA) {
-		err2 = filemap_fdatawait(mapping);
-		if (!err)
-			err = err2;
-	}
-
-	spin_lock(&inode_lock);
-	if ((inode->i_state & I_DIRTY) &&
-	    ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC)))
-		need_write_inode_now = 1;
-	spin_unlock(&inode_lock);
-
-	if (need_write_inode_now) {
-		err2 = write_inode_now(inode, 1);
-		if (!err)
-			err = err2;
-	}
-	else
-		inode_sync_wait(inode);
-
-	return err;
-}
-EXPORT_SYMBOL(generic_osync_inode);