Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

1 files changed, 0 insertions, 3289 deletions

diff --git a/ANDROID_3.4.5/fs/buffer.c b/ANDROID_3.4.5/fs/buffer.c
deleted file mode 100644
index 18669e92..00000000
--- a/ANDROID_3.4.5/fs/buffer.c
+++ /dev/null
@@ -1,3289 +0,0 @@
-/*
- *  linux/fs/buffer.c
- *
- *  Copyright (C) 1991, 1992, 2002  Linus Torvalds
- */
-
-/*
- * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
- *
- * Removed a lot of unnecessary code and simplified things now that
- * the buffer cache isn't our primary cache - Andrew Tridgell 12/96
- *
- * Speed up hash, lru, and free list operations.  Use gfp() for allocating
- * hash table, use SLAB cache for buffer heads. SMP threading.  -DaveM
- *
- * Added 32k buffer block sizes - these are required older ARM systems. - RMK
- *
- * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
- */
-
-#include <linux/kernel.h>
-#include <linux/syscalls.h>
-#include <linux/fs.h>
-#include <linux/mm.h>
-#include <linux/percpu.h>
-#include <linux/slab.h>
-#include <linux/capability.h>
-#include <linux/blkdev.h>
-#include <linux/file.h>
-#include <linux/quotaops.h>
-#include <linux/highmem.h>
-#include <linux/export.h>
-#include <linux/writeback.h>
-#include <linux/hash.h>
-#include <linux/suspend.h>
-#include <linux/buffer_head.h>
-#include <linux/task_io_accounting_ops.h>
-#include <linux/bio.h>
-#include <linux/notifier.h>
-#include <linux/cpu.h>
-#include <linux/bitops.h>
-#include <linux/mpage.h>
-#include <linux/bit_spinlock.h>
-
-static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
-
-#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
-
-inline void
-init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
-{
-	bh->b_end_io = handler;
-	bh->b_private = private;
-}
-EXPORT_SYMBOL(init_buffer);
-
-static int sleep_on_buffer(void *word)
-{
-	io_schedule();
-	return 0;
-}
-
-void __lock_buffer(struct buffer_head *bh)
-{
-	wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer,
-							TASK_UNINTERRUPTIBLE);
-}
-EXPORT_SYMBOL(__lock_buffer);
-
-void unlock_buffer(struct buffer_head *bh)
-{
-	clear_bit_unlock(BH_Lock, &bh->b_state);
-	smp_mb__after_clear_bit();
-	wake_up_bit(&bh->b_state, BH_Lock);
-}
-EXPORT_SYMBOL(unlock_buffer);
-
-/*
- * Block until a buffer comes unlocked.  This doesn't stop it
- * from becoming locked again - you have to lock it yourself
- * if you want to preserve its state.
- */
-void __wait_on_buffer(struct buffer_head * bh)
-{
-	wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE);
-}
-EXPORT_SYMBOL(__wait_on_buffer);
-
-static void
-__clear_page_buffers(struct page *page)
-{
-	ClearPagePrivate(page);
-	set_page_private(page, 0);
-	page_cache_release(page);
-}
-
-
-static int quiet_error(struct buffer_head *bh)
-{
-	if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
-		return 0;
-	return 1;
-}
-
-
-static void buffer_io_error(struct buffer_head *bh)
-{
-	char b[BDEVNAME_SIZE];
-	printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
-			bdevname(bh->b_bdev, b),
-			(unsigned long long)bh->b_blocknr);
-}
-
-/*
- * End-of-IO handler helper function which does not touch the bh after
- * unlocking it.
- * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
- * a race there is benign: unlock_buffer() only use the bh's address for
- * hashing after unlocking the buffer, so it doesn't actually touch the bh
- * itself.
- */
-static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
-{
-	if (uptodate) {
-		set_buffer_uptodate(bh);
-	} else {
-		/* This happens, due to failed READA attempts. */
-		clear_buffer_uptodate(bh);
-	}
-	unlock_buffer(bh);
-}
-
-/*
- * Default synchronous end-of-IO handler..  Just mark it up-to-date and
- * unlock the buffer. This is what ll_rw_block uses too.
- */
-void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
-{
-	__end_buffer_read_notouch(bh, uptodate);
-	put_bh(bh);
-}
-EXPORT_SYMBOL(end_buffer_read_sync);
-
-void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
-{
-	char b[BDEVNAME_SIZE];
-
-	if (uptodate) {
-		set_buffer_uptodate(bh);
-	} else {
-		if (!quiet_error(bh)) {
-			buffer_io_error(bh);
-			printk(KERN_WARNING "lost page write due to "
-					"I/O error on %s\n",
-				       bdevname(bh->b_bdev, b));
-		}
-		set_buffer_write_io_error(bh);
-		clear_buffer_uptodate(bh);
-	}
-	unlock_buffer(bh);
-	put_bh(bh);
-}
-EXPORT_SYMBOL(end_buffer_write_sync);
-
-/*
- * Various filesystems appear to want __find_get_block to be non-blocking.
- * But it's the page lock which protects the buffers.  To get around this,
- * we get exclusion from try_to_free_buffers with the blockdev mapping's
- * private_lock.
- *
- * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
- * may be quite high.  This code could TryLock the page, and if that
- * succeeds, there is no need to take private_lock. (But if
- * private_lock is contended then so is mapping->tree_lock).
- */
-static struct buffer_head *
-__find_get_block_slow(struct block_device *bdev, sector_t block)
-{
-	struct inode *bd_inode = bdev->bd_inode;
-	struct address_space *bd_mapping = bd_inode->i_mapping;
-	struct buffer_head *ret = NULL;
-	pgoff_t index;
-	struct buffer_head *bh;
-	struct buffer_head *head;
-	struct page *page;
-	int all_mapped = 1;
-
-	index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
-	page = find_get_page(bd_mapping, index);
-	if (!page)
-		goto out;
-
-	spin_lock(&bd_mapping->private_lock);
-	if (!page_has_buffers(page))
-		goto out_unlock;
-	head = page_buffers(page);
-	bh = head;
-	do {
-		if (!buffer_mapped(bh))
-			all_mapped = 0;
-		else if (bh->b_blocknr == block) {
-			ret = bh;
-			get_bh(bh);
-			goto out_unlock;
-		}
-		bh = bh->b_this_page;
-	} while (bh != head);
-
-	/* we might be here because some of the buffers on this page are
-	 * not mapped.  This is due to various races between
-	 * file io on the block device and getblk.  It gets dealt with
-	 * elsewhere, don't buffer_error if we had some unmapped buffers
-	 */
-	if (all_mapped) {
-		char b[BDEVNAME_SIZE];
-
-		printk("__find_get_block_slow() failed. "
-			"block=%llu, b_blocknr=%llu\n",
-			(unsigned long long)block,
-			(unsigned long long)bh->b_blocknr);
-		printk("b_state=0x%08lx, b_size=%zu\n",
-			bh->b_state, bh->b_size);
-		printk("device %s blocksize: %d\n", bdevname(bdev, b),
-			1 << bd_inode->i_blkbits);
-	}
-out_unlock:
-	spin_unlock(&bd_mapping->private_lock);
-	page_cache_release(page);
-out:
-	return ret;
-}
-
-/*
- * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
- */
-static void free_more_memory(void)
-{
-	struct zone *zone;
-	int nid;
-
-	wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
-	yield();
-
-	for_each_online_node(nid) {
-		(void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
-						gfp_zone(GFP_NOFS), NULL,
-						&zone);
-		if (zone)
-			try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
-						GFP_NOFS, NULL);
-	}
-}
-
-/*
- * I/O completion handler for block_read_full_page() - pages
- * which come unlocked at the end of I/O.
- */
-static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
-{
-	unsigned long flags;
-	struct buffer_head *first;
-	struct buffer_head *tmp;
-	struct page *page;
-	int page_uptodate = 1;
-
-	BUG_ON(!buffer_async_read(bh));
-
-	page = bh->b_page;
-	if (uptodate) {
-		set_buffer_uptodate(bh);
-	} else {
-		clear_buffer_uptodate(bh);
-		if (!quiet_error(bh))
-			buffer_io_error(bh);
-		SetPageError(page);
-	}
-
-	/*
-	 * Be _very_ careful from here on. Bad things can happen if
-	 * two buffer heads end IO at almost the same time and both
-	 * decide that the page is now completely done.
-	 */
-	first = page_buffers(page);
-	local_irq_save(flags);
-	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
-	clear_buffer_async_read(bh);
-	unlock_buffer(bh);
-	tmp = bh;
-	do {
-		if (!buffer_uptodate(tmp))
-			page_uptodate = 0;
-		if (buffer_async_read(tmp)) {
-			BUG_ON(!buffer_locked(tmp));
-			goto still_busy;
-		}
-		tmp = tmp->b_this_page;
-	} while (tmp != bh);
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
-	local_irq_restore(flags);
-
-	/*
-	 * If none of the buffers had errors and they are all
-	 * uptodate then we can set the page uptodate.
-	 */
-	if (page_uptodate && !PageError(page))
-		SetPageUptodate(page);
-	unlock_page(page);
-	return;
-
-still_busy:
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
-	local_irq_restore(flags);
-	return;
-}
-
-/*
- * Completion handler for block_write_full_page() - pages which are unlocked
- * during I/O, and which have PageWriteback cleared upon I/O completion.
- */
-void end_buffer_async_write(struct buffer_head *bh, int uptodate)
-{
-	char b[BDEVNAME_SIZE];
-	unsigned long flags;
-	struct buffer_head *first;
-	struct buffer_head *tmp;
-	struct page *page;
-
-	BUG_ON(!buffer_async_write(bh));
-
-	page = bh->b_page;
-	if (uptodate) {
-		set_buffer_uptodate(bh);
-	} else {
-		if (!quiet_error(bh)) {
-			buffer_io_error(bh);
-			printk(KERN_WARNING "lost page write due to "
-					"I/O error on %s\n",
-			       bdevname(bh->b_bdev, b));
-		}
-		set_bit(AS_EIO, &page->mapping->flags);
-		set_buffer_write_io_error(bh);
-		clear_buffer_uptodate(bh);
-		SetPageError(page);
-	}
-
-	first = page_buffers(page);
-	local_irq_save(flags);
-	bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
-
-	clear_buffer_async_write(bh);
-	unlock_buffer(bh);
-	tmp = bh->b_this_page;
-	while (tmp != bh) {
-		if (buffer_async_write(tmp)) {
-			BUG_ON(!buffer_locked(tmp));
-			goto still_busy;
-		}
-		tmp = tmp->b_this_page;
-	}
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
-	local_irq_restore(flags);
-	end_page_writeback(page);
-	return;
-
-still_busy:
-	bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
-	local_irq_restore(flags);
-	return;
-}
-EXPORT_SYMBOL(end_buffer_async_write);
-
-/*
- * If a page's buffers are under async readin (end_buffer_async_read
- * completion) then there is a possibility that another thread of
- * control could lock one of the buffers after it has completed
- * but while some of the other buffers have not completed.  This
- * locked buffer would confuse end_buffer_async_read() into not unlocking
- * the page.  So the absence of BH_Async_Read tells end_buffer_async_read()
- * that this buffer is not under async I/O.
- *
- * The page comes unlocked when it has no locked buffer_async buffers
- * left.
- *
- * PageLocked prevents anyone starting new async I/O reads any of
- * the buffers.
- *
- * PageWriteback is used to prevent simultaneous writeout of the same
- * page.
- *
- * PageLocked prevents anyone from starting writeback of a page which is
- * under read I/O (PageWriteback is only ever set against a locked page).
- */
-static void mark_buffer_async_read(struct buffer_head *bh)
-{
-	bh->b_end_io = end_buffer_async_read;
-	set_buffer_async_read(bh);
-}
-
-static void mark_buffer_async_write_endio(struct buffer_head *bh,
-					  bh_end_io_t *handler)
-{
-	bh->b_end_io = handler;
-	set_buffer_async_write(bh);
-}
-
-void mark_buffer_async_write(struct buffer_head *bh)
-{
-	mark_buffer_async_write_endio(bh, end_buffer_async_write);
-}
-EXPORT_SYMBOL(mark_buffer_async_write);
-
-
-/*
- * fs/buffer.c contains helper functions for buffer-backed address space's
- * fsync functions.  A common requirement for buffer-based filesystems is
- * that certain data from the backing blockdev needs to be written out for
- * a successful fsync().  For example, ext2 indirect blocks need to be
- * written back and waited upon before fsync() returns.
- *
- * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
- * inode_has_buffers() and invalidate_inode_buffers() are provided for the
- * management of a list of dependent buffers at ->i_mapping->private_list.
- *
- * Locking is a little subtle: try_to_free_buffers() will remove buffers
- * from their controlling inode's queue when they are being freed.  But
- * try_to_free_buffers() will be operating against the *blockdev* mapping
- * at the time, not against the S_ISREG file which depends on those buffers.
- * So the locking for private_list is via the private_lock in the address_space
- * which backs the buffers.  Which is different from the address_space 
- * against which the buffers are listed.  So for a particular address_space,
- * mapping->private_lock does *not* protect mapping->private_list!  In fact,
- * mapping->private_list will always be protected by the backing blockdev's
- * ->private_lock.
- *
- * Which introduces a requirement: all buffers on an address_space's
- * ->private_list must be from the same address_space: the blockdev's.
- *
- * address_spaces which do not place buffers at ->private_list via these
- * utility functions are free to use private_lock and private_list for
- * whatever they want.  The only requirement is that list_empty(private_list)
- * be true at clear_inode() time.
- *
- * FIXME: clear_inode should not call invalidate_inode_buffers().  The
- * filesystems should do that.  invalidate_inode_buffers() should just go
- * BUG_ON(!list_empty).
- *
- * FIXME: mark_buffer_dirty_inode() is a data-plane operation.  It should
- * take an address_space, not an inode.  And it should be called
- * mark_buffer_dirty_fsync() to clearly define why those buffers are being
- * queued up.
- *
- * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
- * list if it is already on a list.  Because if the buffer is on a list,
- * it *must* already be on the right one.  If not, the filesystem is being
- * silly.  This will save a ton of locking.  But first we have to ensure
- * that buffers are taken *off* the old inode's list when they are freed
- * (presumably in truncate).  That requires careful auditing of all
- * filesystems (do it inside bforget()).  It could also be done by bringing
- * b_inode back.
- */
-
-/*
- * The buffer's backing address_space's private_lock must be held
- */
-static void __remove_assoc_queue(struct buffer_head *bh)
-{
-	list_del_init(&bh->b_assoc_buffers);
-	WARN_ON(!bh->b_assoc_map);
-	if (buffer_write_io_error(bh))
-		set_bit(AS_EIO, &bh->b_assoc_map->flags);
-	bh->b_assoc_map = NULL;
-}
-
-int inode_has_buffers(struct inode *inode)
-{
-	return !list_empty(&inode->i_data.private_list);
-}
-
-/*
- * osync is designed to support O_SYNC io.  It waits synchronously for
- * all already-submitted IO to complete, but does not queue any new
- * writes to the disk.
- *
- * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
- * you dirty the buffers, and then use osync_inode_buffers to wait for
- * completion.  Any other dirty buffers which are not yet queued for
- * write will not be flushed to disk by the osync.
- */
-static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
-{
-	struct buffer_head *bh;
-	struct list_head *p;
-	int err = 0;
-
-	spin_lock(lock);
-repeat:
-	list_for_each_prev(p, list) {
-		bh = BH_ENTRY(p);
-		if (buffer_locked(bh)) {
-			get_bh(bh);
-			spin_unlock(lock);
-			wait_on_buffer(bh);
-			if (!buffer_uptodate(bh))
-				err = -EIO;
-			brelse(bh);
-			spin_lock(lock);
-			goto repeat;
-		}
-	}
-	spin_unlock(lock);
-	return err;
-}
-
-static void do_thaw_one(struct super_block *sb, void *unused)
-{
-	char b[BDEVNAME_SIZE];
-	while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
-		printk(KERN_WARNING "Emergency Thaw on %s\n",
-		       bdevname(sb->s_bdev, b));
-}
-
-static void do_thaw_all(struct work_struct *work)
-{
-	iterate_supers(do_thaw_one, NULL);
-	kfree(work);
-	printk(KERN_WARNING "Emergency Thaw complete\n");
-}
-
-/**
- * emergency_thaw_all -- forcibly thaw every frozen filesystem
- *
- * Used for emergency unfreeze of all filesystems via SysRq
- */
-void emergency_thaw_all(void)
-{
-	struct work_struct *work;
-
-	work = kmalloc(sizeof(*work), GFP_ATOMIC);
-	if (work) {
-		INIT_WORK(work, do_thaw_all);
-		schedule_work(work);
-	}
-}
-
-/**
- * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
- * @mapping: the mapping which wants those buffers written
- *
- * Starts I/O against the buffers at mapping->private_list, and waits upon
- * that I/O.
- *
- * Basically, this is a convenience function for fsync().
- * @mapping is a file or directory which needs those buffers to be written for
- * a successful fsync().
- */
-int sync_mapping_buffers(struct address_space *mapping)
-{
-	struct address_space *buffer_mapping = mapping->assoc_mapping;
-
-	if (buffer_mapping == NULL || list_empty(&mapping->private_list))
-		return 0;
-
-	return fsync_buffers_list(&buffer_mapping->private_lock,
-					&mapping->private_list);
-}
-EXPORT_SYMBOL(sync_mapping_buffers);
-
-/*
- * Called when we've recently written block `bblock', and it is known that
- * `bblock' was for a buffer_boundary() buffer.  This means that the block at
- * `bblock + 1' is probably a dirty indirect block.  Hunt it down and, if it's
- * dirty, schedule it for IO.  So that indirects merge nicely with their data.
- */
-void write_boundary_block(struct block_device *bdev,
-			sector_t bblock, unsigned blocksize)
-{
-	struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
-	if (bh) {
-		if (buffer_dirty(bh))
-			ll_rw_block(WRITE, 1, &bh);
-		put_bh(bh);
-	}
-}
-
-void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
-{
-	struct address_space *mapping = inode->i_mapping;
-	struct address_space *buffer_mapping = bh->b_page->mapping;
-
-	mark_buffer_dirty(bh);
-	if (!mapping->assoc_mapping) {
-		mapping->assoc_mapping = buffer_mapping;
-	} else {
-		BUG_ON(mapping->assoc_mapping != buffer_mapping);
-	}
-	if (!bh->b_assoc_map) {
-		spin_lock(&buffer_mapping->private_lock);
-		list_move_tail(&bh->b_assoc_buffers,
-				&mapping->private_list);
-		bh->b_assoc_map = mapping;
-		spin_unlock(&buffer_mapping->private_lock);
-	}
-}
-EXPORT_SYMBOL(mark_buffer_dirty_inode);
-
-/*
- * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
- * dirty.
- *
- * If warn is true, then emit a warning if the page is not uptodate and has
- * not been truncated.
- */
-static void __set_page_dirty(struct page *page,
-		struct address_space *mapping, int warn)
-{
-	spin_lock_irq(&mapping->tree_lock);
-	if (page->mapping) {	/* Race with truncate? */
-		WARN_ON_ONCE(warn && !PageUptodate(page));
-		account_page_dirtied(page, mapping);
-		radix_tree_tag_set(&mapping->page_tree,
-				page_index(page), PAGECACHE_TAG_DIRTY);
-	}
-	spin_unlock_irq(&mapping->tree_lock);
-	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
-}
-
-/*
- * Add a page to the dirty page list.
- *
- * It is a sad fact of life that this function is called from several places
- * deeply under spinlocking.  It may not sleep.
- *
- * If the page has buffers, the uptodate buffers are set dirty, to preserve
- * dirty-state coherency between the page and the buffers.  It the page does
- * not have buffers then when they are later attached they will all be set
- * dirty.
- *
- * The buffers are dirtied before the page is dirtied.  There's a small race
- * window in which a writepage caller may see the page cleanness but not the
- * buffer dirtiness.  That's fine.  If this code were to set the page dirty
- * before the buffers, a concurrent writepage caller could clear the page dirty
- * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
- * page on the dirty page list.
- *
- * We use private_lock to lock against try_to_free_buffers while using the
- * page's buffer list.  Also use this to protect against clean buffers being
- * added to the page after it was set dirty.
- *
- * FIXME: may need to call ->reservepage here as well.  That's rather up to the
- * address_space though.
- */
-int __set_page_dirty_buffers(struct page *page)
-{
-	int newly_dirty;
-	struct address_space *mapping = page_mapping(page);
-
-	if (unlikely(!mapping))
-		return !TestSetPageDirty(page);
-
-	spin_lock(&mapping->private_lock);
-	if (page_has_buffers(page)) {
-		struct buffer_head *head = page_buffers(page);
-		struct buffer_head *bh = head;
-
-		do {
-			set_buffer_dirty(bh);
-			bh = bh->b_this_page;
-		} while (bh != head);
-	}
-	newly_dirty = !TestSetPageDirty(page);
-	spin_unlock(&mapping->private_lock);
-
-	if (newly_dirty)
-		__set_page_dirty(page, mapping, 1);
-	return newly_dirty;
-}
-EXPORT_SYMBOL(__set_page_dirty_buffers);
-
-/*
- * Write out and wait upon a list of buffers.
- *
- * We have conflicting pressures: we want to make sure that all
- * initially dirty buffers get waited on, but that any subsequently
- * dirtied buffers don't.  After all, we don't want fsync to last
- * forever if somebody is actively writing to the file.
- *
- * Do this in two main stages: first we copy dirty buffers to a
- * temporary inode list, queueing the writes as we go.  Then we clean
- * up, waiting for those writes to complete.
- * 
- * During this second stage, any subsequent updates to the file may end
- * up refiling the buffer on the original inode's dirty list again, so
- * there is a chance we will end up with a buffer queued for write but
- * not yet completed on that list.  So, as a final cleanup we go through
- * the osync code to catch these locked, dirty buffers without requeuing
- * any newly dirty buffers for write.
- */
-static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
-{
-	struct buffer_head *bh;
-	struct list_head tmp;
-	struct address_space *mapping;
-	int err = 0, err2;
-	struct blk_plug plug;
-
-	INIT_LIST_HEAD(&tmp);
-	blk_start_plug(&plug);
-
-	spin_lock(lock);
-	while (!list_empty(list)) {
-		bh = BH_ENTRY(list->next);
-		mapping = bh->b_assoc_map;
-		__remove_assoc_queue(bh);
-		/* Avoid race with mark_buffer_dirty_inode() which does
-		 * a lockless check and we rely on seeing the dirty bit */
-		smp_mb();
-		if (buffer_dirty(bh) || buffer_locked(bh)) {
-			list_add(&bh->b_assoc_buffers, &tmp);
-			bh->b_assoc_map = mapping;
-			if (buffer_dirty(bh)) {
-				get_bh(bh);
-				spin_unlock(lock);
-				/*
-				 * Ensure any pending I/O completes so that
-				 * write_dirty_buffer() actually writes the
-				 * current contents - it is a noop if I/O is
-				 * still in flight on potentially older
-				 * contents.
-				 */
-				write_dirty_buffer(bh, WRITE_SYNC);
-
-				/*
-				 * Kick off IO for the previous mapping. Note
-				 * that we will not run the very last mapping,
-				 * wait_on_buffer() will do that for us
-				 * through sync_buffer().
-				 */
-				brelse(bh);
-				spin_lock(lock);
-			}
-		}
-	}
-
-	spin_unlock(lock);
-	blk_finish_plug(&plug);
-	spin_lock(lock);
-
-	while (!list_empty(&tmp)) {
-		bh = BH_ENTRY(tmp.prev);
-		get_bh(bh);
-		mapping = bh->b_assoc_map;
-		__remove_assoc_queue(bh);
-		/* Avoid race with mark_buffer_dirty_inode() which does
-		 * a lockless check and we rely on seeing the dirty bit */
-		smp_mb();
-		if (buffer_dirty(bh)) {
-			list_add(&bh->b_assoc_buffers,
-				 &mapping->private_list);
-			bh->b_assoc_map = mapping;
-		}
-		spin_unlock(lock);
-		wait_on_buffer(bh);
-		if (!buffer_uptodate(bh))
-			err = -EIO;
-		brelse(bh);
-		spin_lock(lock);
-	}
-	
-	spin_unlock(lock);
-	err2 = osync_buffers_list(lock, list);
-	if (err)
-		return err;
-	else
-		return err2;
-}
-
-/*
- * Invalidate any and all dirty buffers on a given inode.  We are
- * probably unmounting the fs, but that doesn't mean we have already
- * done a sync().  Just drop the buffers from the inode list.
- *
- * NOTE: we take the inode's blockdev's mapping's private_lock.  Which
- * assumes that all the buffers are against the blockdev.  Not true
- * for reiserfs.
- */
-void invalidate_inode_buffers(struct inode *inode)
-{
-	if (inode_has_buffers(inode)) {
-		struct address_space *mapping = &inode->i_data;
-		struct list_head *list = &mapping->private_list;
-		struct address_space *buffer_mapping = mapping->assoc_mapping;
-
-		spin_lock(&buffer_mapping->private_lock);
-		while (!list_empty(list))
-			__remove_assoc_queue(BH_ENTRY(list->next));
-		spin_unlock(&buffer_mapping->private_lock);
-	}
-}
-EXPORT_SYMBOL(invalidate_inode_buffers);
-
-/*
- * Remove any clean buffers from the inode's buffer list.  This is called
- * when we're trying to free the inode itself.  Those buffers can pin it.
- *
- * Returns true if all buffers were removed.
- */
-int remove_inode_buffers(struct inode *inode)
-{
-	int ret = 1;
-
-	if (inode_has_buffers(inode)) {
-		struct address_space *mapping = &inode->i_data;
-		struct list_head *list = &mapping->private_list;
-		struct address_space *buffer_mapping = mapping->assoc_mapping;
-
-		spin_lock(&buffer_mapping->private_lock);
-		while (!list_empty(list)) {
-			struct buffer_head *bh = BH_ENTRY(list->next);
-			if (buffer_dirty(bh)) {
-				ret = 0;
-				break;
-			}
-			__remove_assoc_queue(bh);
-		}
-		spin_unlock(&buffer_mapping->private_lock);
-	}
-	return ret;
-}
-
-/*
- * Create the appropriate buffers when given a page for data area and
- * the size of each buffer.. Use the bh->b_this_page linked list to
- * follow the buffers created.  Return NULL if unable to create more
- * buffers.
- *
- * The retry flag is used to differentiate async IO (paging, swapping)
- * which may not fail from ordinary buffer allocations.
- */
-struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
-		int retry)
-{
-	struct buffer_head *bh, *head;
-	long offset;
-
-try_again:
-	head = NULL;
-	offset = PAGE_SIZE;
-	while ((offset -= size) >= 0) {
-		bh = alloc_buffer_head(GFP_NOFS);
-		if (!bh)
-			goto no_grow;
-
-		bh->b_bdev = NULL;
-		bh->b_this_page = head;
-		bh->b_blocknr = -1;
-		head = bh;
-
-		bh->b_state = 0;
-		atomic_set(&bh->b_count, 0);
-		bh->b_size = size;
-
-		/* Link the buffer to its page */
-		set_bh_page(bh, page, offset);
-
-		init_buffer(bh, NULL, NULL);
-	}
-	return head;
-/*
- * In case anything failed, we just free everything we got.
- */
-no_grow:
-	if (head) {
-		do {
-			bh = head;
-			head = head->b_this_page;
-			free_buffer_head(bh);
-		} while (head);
-	}
-
-	/*
-	 * Return failure for non-async IO requests.  Async IO requests
-	 * are not allowed to fail, so we have to wait until buffer heads
-	 * become available.  But we don't want tasks sleeping with 
-	 * partially complete buffers, so all were released above.
-	 */
-	if (!retry)
-		return NULL;
-
-	/* We're _really_ low on memory. Now we just
-	 * wait for old buffer heads to become free due to
-	 * finishing IO.  Since this is an async request and
-	 * the reserve list is empty, we're sure there are 
-	 * async buffer heads in use.
-	 */
-	free_more_memory();
-	goto try_again;
-}
-EXPORT_SYMBOL_GPL(alloc_page_buffers);
-
-static inline void
-link_dev_buffers(struct page *page, struct buffer_head *head)
-{
-	struct buffer_head *bh, *tail;
-
-	bh = head;
-	do {
-		tail = bh;
-		bh = bh->b_this_page;
-	} while (bh);
-	tail->b_this_page = head;
-	attach_page_buffers(page, head);
-}
-
-/*
- * Initialise the state of a blockdev page's buffers.
- */ 
-static sector_t
-init_page_buffers(struct page *page, struct block_device *bdev,
-			sector_t block, int size)
-{
-	struct buffer_head *head = page_buffers(page);
-	struct buffer_head *bh = head;
-	int uptodate = PageUptodate(page);
-	sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode));
-
-	do {
-		if (!buffer_mapped(bh)) {
-			init_buffer(bh, NULL, NULL);
-			bh->b_bdev = bdev;
-			bh->b_blocknr = block;
-			if (uptodate)
-				set_buffer_uptodate(bh);
-			if (block < end_block)
-				set_buffer_mapped(bh);
-		}
-		block++;
-		bh = bh->b_this_page;
-	} while (bh != head);
-
-	/*
-	 * Caller needs to validate requested block against end of device.
-	 */
-	return end_block;
-}
-
-/*
- * Create the page-cache page that contains the requested block.
- *
- * This is used purely for blockdev mappings.
- */
-static int
-grow_dev_page(struct block_device *bdev, sector_t block,
-		pgoff_t index, int size, int sizebits)
-{
-	struct inode *inode = bdev->bd_inode;
-	struct page *page;
-	struct buffer_head *bh;
-	sector_t end_block;
-	int ret = 0;		/* Will call free_more_memory() */
-
-	page = find_or_create_page(inode->i_mapping, index,
-		(mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
-	if (!page)
-		return ret;
-
-	BUG_ON(!PageLocked(page));
-
-	if (page_has_buffers(page)) {
-		bh = page_buffers(page);
-		if (bh->b_size == size) {
-			end_block = init_page_buffers(page, bdev,
-						index << sizebits, size);
-			goto done;
-		}
-		if (!try_to_free_buffers(page))
-			goto failed;
-	}
-
-	/*
-	 * Allocate some buffers for this page
-	 */
-	bh = alloc_page_buffers(page, size, 0);
-	if (!bh)
-		goto failed;
-
-	/*
-	 * Link the page to the buffers and initialise them.  Take the
-	 * lock to be atomic wrt __find_get_block(), which does not
-	 * run under the page lock.
-	 */
-	spin_lock(&inode->i_mapping->private_lock);
-	link_dev_buffers(page, bh);
-	end_block = init_page_buffers(page, bdev, index << sizebits, size);
-	spin_unlock(&inode->i_mapping->private_lock);
-done:
-	ret = (block < end_block) ? 1 : -ENXIO;
-failed:
-	unlock_page(page);
-	page_cache_release(page);
-	return ret;
-}
-
-/*
- * Create buffers for the specified block device block's page.  If
- * that page was dirty, the buffers are set dirty also.
- */
-static int
-grow_buffers(struct block_device *bdev, sector_t block, int size)
-{
-	pgoff_t index;
-	int sizebits;
-
-	sizebits = -1;
-	do {
-		sizebits++;
-	} while ((size << sizebits) < PAGE_SIZE);
-
-	index = block >> sizebits;
-
-	/*
-	 * Check for a block which wants to lie outside our maximum possible
-	 * pagecache index.  (this comparison is done using sector_t types).
-	 */
-	if (unlikely(index != block >> sizebits)) {
-		char b[BDEVNAME_SIZE];
-
-		printk(KERN_ERR "%s: requested out-of-range block %llu for "
-			"device %s\n",
-			__func__, (unsigned long long)block,
-			bdevname(bdev, b));
-		return -EIO;
-	}
-
-	/* Create a page with the proper size buffers.. */
-	return grow_dev_page(bdev, block, index, size, sizebits);
-}
-
-static struct buffer_head *
-__getblk_slow(struct block_device *bdev, sector_t block, int size)
-{
-	/* Size must be multiple of hard sectorsize */
-	if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
-			(size < 512 || size > PAGE_SIZE))) {
-		printk(KERN_ERR "getblk(): invalid block size %d requested\n",
-					size);
-		printk(KERN_ERR "logical block size: %d\n",
-					bdev_logical_block_size(bdev));
-
-		dump_stack();
-		return NULL;
-	}
-
-	for (;;) {
-		struct buffer_head *bh;
-		int ret;
-
-		bh = __find_get_block(bdev, block, size);
-		if (bh)
-			return bh;
-
-		ret = grow_buffers(bdev, block, size);
-		if (ret < 0)
-			return NULL;
-		if (ret == 0)
-			free_more_memory();
-	}
-}
-
-/*
- * The relationship between dirty buffers and dirty pages:
- *
- * Whenever a page has any dirty buffers, the page's dirty bit is set, and
- * the page is tagged dirty in its radix tree.
- *
- * At all times, the dirtiness of the buffers represents the dirtiness of
- * subsections of the page.  If the page has buffers, the page dirty bit is
- * merely a hint about the true dirty state.
- *
- * When a page is set dirty in its entirety, all its buffers are marked dirty
- * (if the page has buffers).
- *
- * When a buffer is marked dirty, its page is dirtied, but the page's other
- * buffers are not.
- *
- * Also.  When blockdev buffers are explicitly read with bread(), they
- * individually become uptodate.  But their backing page remains not
- * uptodate - even if all of its buffers are uptodate.  A subsequent
- * block_read_full_page() against that page will discover all the uptodate
- * buffers, will set the page uptodate and will perform no I/O.
- */
-
-/**
- * mark_buffer_dirty - mark a buffer_head as needing writeout
- * @bh: the buffer_head to mark dirty
- *
- * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
- * backing page dirty, then tag the page as dirty in its address_space's radix
- * tree and then attach the address_space's inode to its superblock's dirty
- * inode list.
- *
- * mark_buffer_dirty() is atomic.  It takes bh->b_page->mapping->private_lock,
- * mapping->tree_lock and mapping->host->i_lock.
- */
-void mark_buffer_dirty(struct buffer_head *bh)
-{
-	WARN_ON_ONCE(!buffer_uptodate(bh));
-
-	/*
-	 * Very *carefully* optimize the it-is-already-dirty case.
-	 *
-	 * Don't let the final "is it dirty" escape to before we
-	 * perhaps modified the buffer.
-	 */
-	if (buffer_dirty(bh)) {
-		smp_mb();
-		if (buffer_dirty(bh))
-			return;
-	}
-
-	if (!test_set_buffer_dirty(bh)) {
-		struct page *page = bh->b_page;
-		if (!TestSetPageDirty(page)) {
-			struct address_space *mapping = page_mapping(page);
-			if (mapping)
-				__set_page_dirty(page, mapping, 0);
-		}
-	}
-}
-EXPORT_SYMBOL(mark_buffer_dirty);
-
-/*
- * Decrement a buffer_head's reference count.  If all buffers against a page
- * have zero reference count, are clean and unlocked, and if the page is clean
- * and unlocked then try_to_free_buffers() may strip the buffers from the page
- * in preparation for freeing it (sometimes, rarely, buffers are removed from
- * a page but it ends up not being freed, and buffers may later be reattached).
- */
-void __brelse(struct buffer_head * buf)
-{
-	if (atomic_read(&buf->b_count)) {
-		put_bh(buf);
-		return;
-	}
-	WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
-}
-EXPORT_SYMBOL(__brelse);
-
-/*
- * bforget() is like brelse(), except it discards any
- * potentially dirty data.
- */
-void __bforget(struct buffer_head *bh)
-{
-	clear_buffer_dirty(bh);
-	if (bh->b_assoc_map) {
-		struct address_space *buffer_mapping = bh->b_page->mapping;
-
-		spin_lock(&buffer_mapping->private_lock);
-		list_del_init(&bh->b_assoc_buffers);
-		bh->b_assoc_map = NULL;
-		spin_unlock(&buffer_mapping->private_lock);
-	}
-	__brelse(bh);
-}
-EXPORT_SYMBOL(__bforget);
-
-static struct buffer_head *__bread_slow(struct buffer_head *bh)
-{
-	lock_buffer(bh);
-	if (buffer_uptodate(bh)) {
-		unlock_buffer(bh);
-		return bh;
-	} else {
-		get_bh(bh);
-		bh->b_end_io = end_buffer_read_sync;
-		submit_bh(READ, bh);
-		wait_on_buffer(bh);
-		if (buffer_uptodate(bh))
-			return bh;
-	}
-	brelse(bh);
-	return NULL;
-}
-
-/*
- * Per-cpu buffer LRU implementation.  To reduce the cost of __find_get_block().
- * The bhs[] array is sorted - newest buffer is at bhs[0].  Buffers have their
- * refcount elevated by one when they're in an LRU.  A buffer can only appear
- * once in a particular CPU's LRU.  A single buffer can be present in multiple
- * CPU's LRUs at the same time.
- *
- * This is a transparent caching front-end to sb_bread(), sb_getblk() and
- * sb_find_get_block().
- *
- * The LRUs themselves only need locking against invalidate_bh_lrus.  We use
- * a local interrupt disable for that.
- */
-
-#define BH_LRU_SIZE	8
-
-struct bh_lru {
-	struct buffer_head *bhs[BH_LRU_SIZE];
-};
-
-static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
-
-#ifdef CONFIG_SMP
-#define bh_lru_lock()	local_irq_disable()
-#define bh_lru_unlock()	local_irq_enable()
-#else
-#define bh_lru_lock()	preempt_disable()
-#define bh_lru_unlock()	preempt_enable()
-#endif
-
-static inline void check_irqs_on(void)
-{
-#ifdef irqs_disabled
-	BUG_ON(irqs_disabled());
-#endif
-}
-
-/*
- * The LRU management algorithm is dopey-but-simple.  Sorry.
- */
-static void bh_lru_install(struct buffer_head *bh)
-{
-	struct buffer_head *evictee = NULL;
-
-	check_irqs_on();
-	bh_lru_lock();
-	if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
-		struct buffer_head *bhs[BH_LRU_SIZE];
-		int in;
-		int out = 0;
-
-		get_bh(bh);
-		bhs[out++] = bh;
-		for (in = 0; in < BH_LRU_SIZE; in++) {
-			struct buffer_head *bh2 =
-				__this_cpu_read(bh_lrus.bhs[in]);
-
-			if (bh2 == bh) {
-				__brelse(bh2);
-			} else {
-				if (out >= BH_LRU_SIZE) {
-					BUG_ON(evictee != NULL);
-					evictee = bh2;
-				} else {
-					bhs[out++] = bh2;
-				}
-			}
-		}
-		while (out < BH_LRU_SIZE)
-			bhs[out++] = NULL;
-		memcpy(__this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
-	}
-	bh_lru_unlock();
-
-	if (evictee)
-		__brelse(evictee);
-}
-
-/*
- * Look up the bh in this cpu's LRU.  If it's there, move it to the head.
- */
-static struct buffer_head *
-lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
-{
-	struct buffer_head *ret = NULL;
-	unsigned int i;
-
-	check_irqs_on();
-	bh_lru_lock();
-	for (i = 0; i < BH_LRU_SIZE; i++) {
-		struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
-
-		if (bh && bh->b_bdev == bdev &&
-				bh->b_blocknr == block && bh->b_size == size) {
-			if (i) {
-				while (i) {
-					__this_cpu_write(bh_lrus.bhs[i],
-						__this_cpu_read(bh_lrus.bhs[i - 1]));
-					i--;
-				}
-				__this_cpu_write(bh_lrus.bhs[0], bh);
-			}
-			get_bh(bh);
-			ret = bh;
-			break;
-		}
-	}
-	bh_lru_unlock();
-	return ret;
-}
-
-/*
- * Perform a pagecache lookup for the matching buffer.  If it's there, refresh
- * it in the LRU and mark it as accessed.  If it is not present then return
- * NULL
- */
-struct buffer_head *
-__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
-{
-	struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
-
-	if (bh == NULL) {
-		bh = __find_get_block_slow(bdev, block);
-		if (bh)
-			bh_lru_install(bh);
-	}
-	if (bh)
-		touch_buffer(bh);
-	return bh;
-}
-EXPORT_SYMBOL(__find_get_block);
-
-/*
- * __getblk will locate (and, if necessary, create) the buffer_head
- * which corresponds to the passed block_device, block and size. The
- * returned buffer has its reference count incremented.
- *
- * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
- * attempt is failing.  FIXME, perhaps?
- */
-struct buffer_head *
-__getblk(struct block_device *bdev, sector_t block, unsigned size)
-{
-	struct buffer_head *bh = __find_get_block(bdev, block, size);
-
-	might_sleep();
-	if (bh == NULL)
-		bh = __getblk_slow(bdev, block, size);
-	return bh;
-}
-EXPORT_SYMBOL(__getblk);
-
-/*
- * Do async read-ahead on a buffer..
- */
-void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
-{
-	struct buffer_head *bh = __getblk(bdev, block, size);
-	if (likely(bh)) {
-		ll_rw_block(READA, 1, &bh);
-		brelse(bh);
-	}
-}
-EXPORT_SYMBOL(__breadahead);
-
-/**
- *  __bread() - reads a specified block and returns the bh
- *  @bdev: the block_device to read from
- *  @block: number of block
- *  @size: size (in bytes) to read
- * 
- *  Reads a specified block, and returns buffer head that contains it.
- *  It returns NULL if the block was unreadable.
- */
-struct buffer_head *
-__bread(struct block_device *bdev, sector_t block, unsigned size)
-{
-	struct buffer_head *bh = __getblk(bdev, block, size);
-
-	if (likely(bh) && !buffer_uptodate(bh))
-		bh = __bread_slow(bh);
-	return bh;
-}
-EXPORT_SYMBOL(__bread);
-
-/*
- * invalidate_bh_lrus() is called rarely - but not only at unmount.
- * This doesn't race because it runs in each cpu either in irq
- * or with preempt disabled.
- */
-static void invalidate_bh_lru(void *arg)
-{
-	struct bh_lru *b = &get_cpu_var(bh_lrus);
-	int i;
-
-	for (i = 0; i < BH_LRU_SIZE; i++) {
-		brelse(b->bhs[i]);
-		b->bhs[i] = NULL;
-	}
-	put_cpu_var(bh_lrus);
-}
-
-static bool has_bh_in_lru(int cpu, void *dummy)
-{
-	struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
-	int i;
-	
-	for (i = 0; i < BH_LRU_SIZE; i++) {
-		if (b->bhs[i])
-			return 1;
-	}
-
-	return 0;
-}
-
-void invalidate_bh_lrus(void)
-{
-	on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL);
-}
-EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
-
-void set_bh_page(struct buffer_head *bh,
-		struct page *page, unsigned long offset)
-{
-	bh->b_page = page;
-	BUG_ON(offset >= PAGE_SIZE);
-	if (PageHighMem(page))
-		/*
-		 * This catches illegal uses and preserves the offset:
-		 */
-		bh->b_data = (char *)(0 + offset);
-	else
-		bh->b_data = page_address(page) + offset;
-}
-EXPORT_SYMBOL(set_bh_page);
-
-/*
- * Called when truncating a buffer on a page completely.
- */
-static void discard_buffer(struct buffer_head * bh)
-{
-	lock_buffer(bh);
-	clear_buffer_dirty(bh);
-	bh->b_bdev = NULL;
-	clear_buffer_mapped(bh);
-	clear_buffer_req(bh);
-	clear_buffer_new(bh);
-	clear_buffer_delay(bh);
-	clear_buffer_unwritten(bh);
-	unlock_buffer(bh);
-}
-
-/**
- * block_invalidatepage - invalidate part or all of a buffer-backed page
- *
- * @page: the page which is affected
- * @offset: the index of the truncation point
- *
- * block_invalidatepage() is called when all or part of the page has become
- * invalidated by a truncate operation.
- *
- * block_invalidatepage() does not have to release all buffers, but it must
- * ensure that no dirty buffer is left outside @offset and that no I/O
- * is underway against any of the blocks which are outside the truncation
- * point.  Because the caller is about to free (and possibly reuse) those
- * blocks on-disk.
- */
-void block_invalidatepage(struct page *page, unsigned long offset)
-{
-	struct buffer_head *head, *bh, *next;
-	unsigned int curr_off = 0;
-
-	BUG_ON(!PageLocked(page));
-	if (!page_has_buffers(page))
-		goto out;
-
-	head = page_buffers(page);
-	bh = head;
-	do {
-		unsigned int next_off = curr_off + bh->b_size;
-		next = bh->b_this_page;
-
-		/*
-		 * is this block fully invalidated?
-		 */
-		if (offset <= curr_off)
-			discard_buffer(bh);
-		curr_off = next_off;
-		bh = next;
-	} while (bh != head);
-
-	/*
-	 * We release buffers only if the entire page is being invalidated.
-	 * The get_block cached value has been unconditionally invalidated,
-	 * so real IO is not possible anymore.
-	 */
-	if (offset == 0)
-		try_to_release_page(page, 0);
-out:
-	return;
-}
-EXPORT_SYMBOL(block_invalidatepage);
-
-/*
- * We attach and possibly dirty the buffers atomically wrt
- * __set_page_dirty_buffers() via private_lock.  try_to_free_buffers
- * is already excluded via the page lock.
- */
-void create_empty_buffers(struct page *page,
-			unsigned long blocksize, unsigned long b_state)
-{
-	struct buffer_head *bh, *head, *tail;
-
-	head = alloc_page_buffers(page, blocksize, 1);
-	bh = head;
-	do {
-		bh->b_state |= b_state;
-		tail = bh;
-		bh = bh->b_this_page;
-	} while (bh);
-	tail->b_this_page = head;
-
-	spin_lock(&page->mapping->private_lock);
-	if (PageUptodate(page) || PageDirty(page)) {
-		bh = head;
-		do {
-			if (PageDirty(page))
-				set_buffer_dirty(bh);
-			if (PageUptodate(page))
-				set_buffer_uptodate(bh);
-			bh = bh->b_this_page;
-		} while (bh != head);
-	}
-	attach_page_buffers(page, head);
-	spin_unlock(&page->mapping->private_lock);
-}
-EXPORT_SYMBOL(create_empty_buffers);
-
-/*
- * We are taking a block for data and we don't want any output from any
- * buffer-cache aliases starting from return from that function and
- * until the moment when something will explicitly mark the buffer
- * dirty (hopefully that will not happen until we will free that block ;-)
- * We don't even need to mark it not-uptodate - nobody can expect
- * anything from a newly allocated buffer anyway. We used to used
- * unmap_buffer() for such invalidation, but that was wrong. We definitely
- * don't want to mark the alias unmapped, for example - it would confuse
- * anyone who might pick it with bread() afterwards...
- *
- * Also..  Note that bforget() doesn't lock the buffer.  So there can
- * be writeout I/O going on against recently-freed buffers.  We don't
- * wait on that I/O in bforget() - it's more efficient to wait on the I/O
- * only if we really need to.  That happens here.
- */
-void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
-{
-	struct buffer_head *old_bh;
-
-	might_sleep();
-
-	old_bh = __find_get_block_slow(bdev, block);
-	if (old_bh) {
-		clear_buffer_dirty(old_bh);
-		wait_on_buffer(old_bh);
-		clear_buffer_req(old_bh);
-		__brelse(old_bh);
-	}
-}
-EXPORT_SYMBOL(unmap_underlying_metadata);
-
-/*
- * NOTE! All mapped/uptodate combinations are valid:
- *
- *	Mapped	Uptodate	Meaning
- *
- *	No	No		"unknown" - must do get_block()
- *	No	Yes		"hole" - zero-filled
- *	Yes	No		"allocated" - allocated on disk, not read in
- *	Yes	Yes		"valid" - allocated and up-to-date in memory.
- *
- * "Dirty" is valid only with the last case (mapped+uptodate).
- */
-
-/*
- * While block_write_full_page is writing back the dirty buffers under
- * the page lock, whoever dirtied the buffers may decide to clean them
- * again at any time.  We handle that by only looking at the buffer
- * state inside lock_buffer().
- *
- * If block_write_full_page() is called for regular writeback
- * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
- * locked buffer.   This only can happen if someone has written the buffer
- * directly, with submit_bh().  At the address_space level PageWriteback
- * prevents this contention from occurring.
- *
- * If block_write_full_page() is called with wbc->sync_mode ==
- * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this
- * causes the writes to be flagged as synchronous writes.
- */
-static int __block_write_full_page(struct inode *inode, struct page *page,
-			get_block_t *get_block, struct writeback_control *wbc,
-			bh_end_io_t *handler)
-{
-	int err;
-	sector_t block;
-	sector_t last_block;
-	struct buffer_head *bh, *head;
-	const unsigned blocksize = 1 << inode->i_blkbits;
-	int nr_underway = 0;
-	int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
-			WRITE_SYNC : WRITE);
-
-	BUG_ON(!PageLocked(page));
-
-	last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
-
-	if (!page_has_buffers(page)) {
-		create_empty_buffers(page, blocksize,
-					(1 << BH_Dirty)|(1 << BH_Uptodate));
-	}
-
-	/*
-	 * Be very careful.  We have no exclusion from __set_page_dirty_buffers
-	 * here, and the (potentially unmapped) buffers may become dirty at
-	 * any time.  If a buffer becomes dirty here after we've inspected it
-	 * then we just miss that fact, and the page stays dirty.
-	 *
-	 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
-	 * handle that here by just cleaning them.
-	 */
-
-	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-	head = page_buffers(page);
-	bh = head;
-
-	/*
-	 * Get all the dirty buffers mapped to disk addresses and
-	 * handle any aliases from the underlying blockdev's mapping.
-	 */
-	do {
-		if (block > last_block) {
-			/*
-			 * mapped buffers outside i_size will occur, because
-			 * this page can be outside i_size when there is a
-			 * truncate in progress.
-			 */
-			/*
-			 * The buffer was zeroed by block_write_full_page()
-			 */
-			clear_buffer_dirty(bh);
-			set_buffer_uptodate(bh);
-		} else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
-			   buffer_dirty(bh)) {
-			WARN_ON(bh->b_size != blocksize);
-			err = get_block(inode, block, bh, 1);
-			if (err)
-				goto recover;
-			clear_buffer_delay(bh);
-			if (buffer_new(bh)) {
-				/* blockdev mappings never come here */
-				clear_buffer_new(bh);
-				unmap_underlying_metadata(bh->b_bdev,
-							bh->b_blocknr);
-			}
-		}
-		bh = bh->b_this_page;
-		block++;
-	} while (bh != head);
-
-	do {
-		if (!buffer_mapped(bh))
-			continue;
-		/*
-		 * If it's a fully non-blocking write attempt and we cannot
-		 * lock the buffer then redirty the page.  Note that this can
-		 * potentially cause a busy-wait loop from writeback threads
-		 * and kswapd activity, but those code paths have their own
-		 * higher-level throttling.
-		 */
-		if (wbc->sync_mode != WB_SYNC_NONE) {
-			lock_buffer(bh);
-		} else if (!trylock_buffer(bh)) {
-			redirty_page_for_writepage(wbc, page);
-			continue;
-		}
-		if (test_clear_buffer_dirty(bh)) {
-			mark_buffer_async_write_endio(bh, handler);
-		} else {
-			unlock_buffer(bh);
-		}
-	} while ((bh = bh->b_this_page) != head);
-
-	/*
-	 * The page and its buffers are protected by PageWriteback(), so we can
-	 * drop the bh refcounts early.
-	 */
-	BUG_ON(PageWriteback(page));
-	set_page_writeback(page);
-
-	do {
-		struct buffer_head *next = bh->b_this_page;
-		if (buffer_async_write(bh)) {
-			submit_bh(write_op, bh);
-			nr_underway++;
-		}
-		bh = next;
-	} while (bh != head);
-	unlock_page(page);
-
-	err = 0;
-done:
-	if (nr_underway == 0) {
-		/*
-		 * The page was marked dirty, but the buffers were
-		 * clean.  Someone wrote them back by hand with
-		 * ll_rw_block/submit_bh.  A rare case.
-		 */
-		end_page_writeback(page);
-
-		/*
-		 * The page and buffer_heads can be released at any time from
-		 * here on.
-		 */
-	}
-	return err;
-
-recover:
-	/*
-	 * ENOSPC, or some other error.  We may already have added some
-	 * blocks to the file, so we need to write these out to avoid
-	 * exposing stale data.
-	 * The page is currently locked and not marked for writeback
-	 */
-	bh = head;
-	/* Recovery: lock and submit the mapped buffers */
-	do {
-		if (buffer_mapped(bh) && buffer_dirty(bh) &&
-		    !buffer_delay(bh)) {
-			lock_buffer(bh);
-			mark_buffer_async_write_endio(bh, handler);
-		} else {
-			/*
-			 * The buffer may have been set dirty during
-			 * attachment to a dirty page.
-			 */
-			clear_buffer_dirty(bh);
-		}
-	} while ((bh = bh->b_this_page) != head);
-	SetPageError(page);
-	BUG_ON(PageWriteback(page));
-	mapping_set_error(page->mapping, err);
-	set_page_writeback(page);
-	do {
-		struct buffer_head *next = bh->b_this_page;
-		if (buffer_async_write(bh)) {
-			clear_buffer_dirty(bh);
-			submit_bh(write_op, bh);
-			nr_underway++;
-		}
-		bh = next;
-	} while (bh != head);
-	unlock_page(page);
-	goto done;
-}
-
-/*
- * If a page has any new buffers, zero them out here, and mark them uptodate
- * and dirty so they'll be written out (in order to prevent uninitialised
- * block data from leaking). And clear the new bit.
- */
-void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
-{
-	unsigned int block_start, block_end;
-	struct buffer_head *head, *bh;
-
-	BUG_ON(!PageLocked(page));
-	if (!page_has_buffers(page))
-		return;
-
-	bh = head = page_buffers(page);
-	block_start = 0;
-	do {
-		block_end = block_start + bh->b_size;
-
-		if (buffer_new(bh)) {
-			if (block_end > from && block_start < to) {
-				if (!PageUptodate(page)) {
-					unsigned start, size;
-
-					start = max(from, block_start);
-					size = min(to, block_end) - start;
-
-					zero_user(page, start, size);
-					set_buffer_uptodate(bh);
-				}
-
-				clear_buffer_new(bh);
-				mark_buffer_dirty(bh);
-			}
-		}
-
-		block_start = block_end;
-		bh = bh->b_this_page;
-	} while (bh != head);
-}
-EXPORT_SYMBOL(page_zero_new_buffers);
-
-int __block_write_begin(struct page *page, loff_t pos, unsigned len,
-		get_block_t *get_block)
-{
-	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
-	unsigned to = from + len;
-	struct inode *inode = page->mapping->host;
-	unsigned block_start, block_end;
-	sector_t block;
-	int err = 0;
-	unsigned blocksize, bbits;
-	struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
-
-	BUG_ON(!PageLocked(page));
-	BUG_ON(from > PAGE_CACHE_SIZE);
-	BUG_ON(to > PAGE_CACHE_SIZE);
-	BUG_ON(from > to);
-
-	blocksize = 1 << inode->i_blkbits;
-	if (!page_has_buffers(page))
-		create_empty_buffers(page, blocksize, 0);
-	head = page_buffers(page);
-
-	bbits = inode->i_blkbits;
-	block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
-
-	for(bh = head, block_start = 0; bh != head || !block_start;
-	    block++, block_start=block_end, bh = bh->b_this_page) {
-		block_end = block_start + blocksize;
-		if (block_end <= from || block_start >= to) {
-			if (PageUptodate(page)) {
-				if (!buffer_uptodate(bh))
-					set_buffer_uptodate(bh);
-			}
-			continue;
-		}
-		if (buffer_new(bh))
-			clear_buffer_new(bh);
-		if (!buffer_mapped(bh)) {
-			WARN_ON(bh->b_size != blocksize);
-			err = get_block(inode, block, bh, 1);
-			if (err)
-				break;
-			if (buffer_new(bh)) {
-				unmap_underlying_metadata(bh->b_bdev,
-							bh->b_blocknr);
-				if (PageUptodate(page)) {
-					clear_buffer_new(bh);
-					set_buffer_uptodate(bh);
-					mark_buffer_dirty(bh);
-					continue;
-				}
-				if (block_end > to || block_start < from)
-					zero_user_segments(page,
-						to, block_end,
-						block_start, from);
-				continue;
-			}
-		}
-		if (PageUptodate(page)) {
-			if (!buffer_uptodate(bh))
-				set_buffer_uptodate(bh);
-			continue; 
-		}
-		if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
-		    !buffer_unwritten(bh) &&
-		     (block_start < from || block_end > to)) {
-			ll_rw_block(READ, 1, &bh);
-			*wait_bh++=bh;
-		}
-	}
-	/*
-	 * If we issued read requests - let them complete.
-	 */
-	while(wait_bh > wait) {
-		wait_on_buffer(*--wait_bh);
-		if (!buffer_uptodate(*wait_bh))
-			err = -EIO;
-	}
-	if (unlikely(err))
-		page_zero_new_buffers(page, from, to);
-	return err;
-}
-EXPORT_SYMBOL(__block_write_begin);
-
-static int __block_commit_write(struct inode *inode, struct page *page,
-		unsigned from, unsigned to)
-{
-	unsigned block_start, block_end;
-	int partial = 0;
-	unsigned blocksize;
-	struct buffer_head *bh, *head;
-
-	blocksize = 1 << inode->i_blkbits;
-
-	for(bh = head = page_buffers(page), block_start = 0;
-	    bh != head || !block_start;
-	    block_start=block_end, bh = bh->b_this_page) {
-		block_end = block_start + blocksize;
-		if (block_end <= from || block_start >= to) {
-			if (!buffer_uptodate(bh))
-				partial = 1;
-		} else {
-			set_buffer_uptodate(bh);
-			mark_buffer_dirty(bh);
-		}
-		clear_buffer_new(bh);
-	}
-
-	/*
-	 * If this is a partial write which happened to make all buffers
-	 * uptodate then we can optimize away a bogus readpage() for
-	 * the next read(). Here we 'discover' whether the page went
-	 * uptodate as a result of this (potentially partial) write.
-	 */
-	if (!partial)
-		SetPageUptodate(page);
-	return 0;
-}
-
-/*
- * block_write_begin takes care of the basic task of block allocation and
- * bringing partial write blocks uptodate first.
- *
- * The filesystem needs to handle block truncation upon failure.
- */
-int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
-		unsigned flags, struct page **pagep, get_block_t *get_block)
-{
-	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
-	struct page *page;
-	int status;
-
-	page = grab_cache_page_write_begin(mapping, index, flags);
-	if (!page)
-		return -ENOMEM;
-
-	status = __block_write_begin(page, pos, len, get_block);
-	if (unlikely(status)) {
-		unlock_page(page);
-		page_cache_release(page);
-		page = NULL;
-	}
-
-	*pagep = page;
-	return status;
-}
-EXPORT_SYMBOL(block_write_begin);
-
-int block_write_end(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned copied,
-			struct page *page, void *fsdata)
-{
-	struct inode *inode = mapping->host;
-	unsigned start;
-
-	start = pos & (PAGE_CACHE_SIZE - 1);
-
-	if (unlikely(copied < len)) {
-		/*
-		 * The buffers that were written will now be uptodate, so we
-		 * don't have to worry about a readpage reading them and
-		 * overwriting a partial write. However if we have encountered
-		 * a short write and only partially written into a buffer, it
-		 * will not be marked uptodate, so a readpage might come in and
-		 * destroy our partial write.
-		 *
-		 * Do the simplest thing, and just treat any short write to a
-		 * non uptodate page as a zero-length write, and force the
-		 * caller to redo the whole thing.
-		 */
-		if (!PageUptodate(page))
-			copied = 0;
-
-		page_zero_new_buffers(page, start+copied, start+len);
-	}
-	flush_dcache_page(page);
-
-	/* This could be a short (even 0-length) commit */
-	__block_commit_write(inode, page, start, start+copied);
-
-	return copied;
-}
-EXPORT_SYMBOL(block_write_end);
-
-int generic_write_end(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned copied,
-			struct page *page, void *fsdata)
-{
-	struct inode *inode = mapping->host;
-	int i_size_changed = 0;
-
-	copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
-
-	/*
-	 * No need to use i_size_read() here, the i_size
-	 * cannot change under us because we hold i_mutex.
-	 *
-	 * But it's important to update i_size while still holding page lock:
-	 * page writeout could otherwise come in and zero beyond i_size.
-	 */
-	if (pos+copied > inode->i_size) {
-		i_size_write(inode, pos+copied);
-		i_size_changed = 1;
-	}
-
-	unlock_page(page);
-	page_cache_release(page);
-
-	/*
-	 * Don't mark the inode dirty under page lock. First, it unnecessarily
-	 * makes the holding time of page lock longer. Second, it forces lock
-	 * ordering of page lock and transaction start for journaling
-	 * filesystems.
-	 */
-	if (i_size_changed)
-		mark_inode_dirty(inode);
-
-	return copied;
-}
-EXPORT_SYMBOL(generic_write_end);
-
-/*
- * block_is_partially_uptodate checks whether buffers within a page are
- * uptodate or not.
- *
- * Returns true if all buffers which correspond to a file portion
- * we want to read are uptodate.
- */
-int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
-					unsigned long from)
-{
-	struct inode *inode = page->mapping->host;
-	unsigned block_start, block_end, blocksize;
-	unsigned to;
-	struct buffer_head *bh, *head;
-	int ret = 1;
-
-	if (!page_has_buffers(page))
-		return 0;
-
-	blocksize = 1 << inode->i_blkbits;
-	to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
-	to = from + to;
-	if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
-		return 0;
-
-	head = page_buffers(page);
-	bh = head;
-	block_start = 0;
-	do {
-		block_end = block_start + blocksize;
-		if (block_end > from && block_start < to) {
-			if (!buffer_uptodate(bh)) {
-				ret = 0;
-				break;
-			}
-			if (block_end >= to)
-				break;
-		}
-		block_start = block_end;
-		bh = bh->b_this_page;
-	} while (bh != head);
-
-	return ret;
-}
-EXPORT_SYMBOL(block_is_partially_uptodate);
-
-/*
- * Generic "read page" function for block devices that have the normal
- * get_block functionality. This is most of the block device filesystems.
- * Reads the page asynchronously --- the unlock_buffer() and
- * set/clear_buffer_uptodate() functions propagate buffer state into the
- * page struct once IO has completed.
- */
-int block_read_full_page(struct page *page, get_block_t *get_block)
-{
-	struct inode *inode = page->mapping->host;
-	sector_t iblock, lblock;
-	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
-	unsigned int blocksize;
-	int nr, i;
-	int fully_mapped = 1;
-
-	BUG_ON(!PageLocked(page));
-	blocksize = 1 << inode->i_blkbits;
-	if (!page_has_buffers(page))
-		create_empty_buffers(page, blocksize, 0);
-	head = page_buffers(page);
-
-	iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-	lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
-	bh = head;
-	nr = 0;
-	i = 0;
-
-	do {
-		if (buffer_uptodate(bh))
-			continue;
-
-		if (!buffer_mapped(bh)) {
-			int err = 0;
-
-			fully_mapped = 0;
-			if (iblock < lblock) {
-				WARN_ON(bh->b_size != blocksize);
-				err = get_block(inode, iblock, bh, 0);
-				if (err)
-					SetPageError(page);
-			}
-			if (!buffer_mapped(bh)) {
-				zero_user(page, i * blocksize, blocksize);
-				if (!err)
-					set_buffer_uptodate(bh);
-				continue;
-			}
-			/*
-			 * get_block() might have updated the buffer
-			 * synchronously
-			 */
-			if (buffer_uptodate(bh))
-				continue;
-		}
-		arr[nr++] = bh;
-	} while (i++, iblock++, (bh = bh->b_this_page) != head);
-
-	if (fully_mapped)
-		SetPageMappedToDisk(page);
-
-	if (!nr) {
-		/*
-		 * All buffers are uptodate - we can set the page uptodate
-		 * as well. But not if get_block() returned an error.
-		 */
-		if (!PageError(page))
-			SetPageUptodate(page);
-		unlock_page(page);
-		return 0;
-	}
-
-	/* Stage two: lock the buffers */
-	for (i = 0; i < nr; i++) {
-		bh = arr[i];
-		lock_buffer(bh);
-		mark_buffer_async_read(bh);
-	}
-
-	/*
-	 * Stage 3: start the IO.  Check for uptodateness
-	 * inside the buffer lock in case another process reading
-	 * the underlying blockdev brought it uptodate (the sct fix).
-	 */
-	for (i = 0; i < nr; i++) {
-		bh = arr[i];
-		if (buffer_uptodate(bh))
-			end_buffer_async_read(bh, 1);
-		else
-			submit_bh(READ, bh);
-	}
-	return 0;
-}
-EXPORT_SYMBOL(block_read_full_page);
-
-/* utility function for filesystems that need to do work on expanding
- * truncates.  Uses filesystem pagecache writes to allow the filesystem to
- * deal with the hole.  
- */
-int generic_cont_expand_simple(struct inode *inode, loff_t size)
-{
-	struct address_space *mapping = inode->i_mapping;
-	struct page *page;
-	void *fsdata;
-	int err;
-
-	err = inode_newsize_ok(inode, size);
-	if (err)
-		goto out;
-
-	err = pagecache_write_begin(NULL, mapping, size, 0,
-				AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
-				&page, &fsdata);
-	if (err)
-		goto out;
-
-	err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
-	BUG_ON(err > 0);
-
-out:
-	return err;
-}
-EXPORT_SYMBOL(generic_cont_expand_simple);
-
-static int cont_expand_zero(struct file *file, struct address_space *mapping,
-			    loff_t pos, loff_t *bytes)
-{
-	struct inode *inode = mapping->host;
-	unsigned blocksize = 1 << inode->i_blkbits;
-	struct page *page;
-	void *fsdata;
-	pgoff_t index, curidx;
-	loff_t curpos;
-	unsigned zerofrom, offset, len;
-	int err = 0;
-
-	index = pos >> PAGE_CACHE_SHIFT;
-	offset = pos & ~PAGE_CACHE_MASK;
-
-	while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
-		zerofrom = curpos & ~PAGE_CACHE_MASK;
-		if (zerofrom & (blocksize-1)) {
-			*bytes |= (blocksize-1);
-			(*bytes)++;
-		}
-		len = PAGE_CACHE_SIZE - zerofrom;
-
-		err = pagecache_write_begin(file, mapping, curpos, len,
-						AOP_FLAG_UNINTERRUPTIBLE,
-						&page, &fsdata);
-		if (err)
-			goto out;
-		zero_user(page, zerofrom, len);
-		err = pagecache_write_end(file, mapping, curpos, len, len,
-						page, fsdata);
-		if (err < 0)
-			goto out;
-		BUG_ON(err != len);
-		err = 0;
-
-		balance_dirty_pages_ratelimited(mapping);
-	}
-
-	/* page covers the boundary, find the boundary offset */
-	if (index == curidx) {
-		zerofrom = curpos & ~PAGE_CACHE_MASK;
-		/* if we will expand the thing last block will be filled */
-		if (offset <= zerofrom) {
-			goto out;
-		}
-		if (zerofrom & (blocksize-1)) {
-			*bytes |= (blocksize-1);
-			(*bytes)++;
-		}
-		len = offset - zerofrom;
-
-		err = pagecache_write_begin(file, mapping, curpos, len,
-						AOP_FLAG_UNINTERRUPTIBLE,
-						&page, &fsdata);
-		if (err)
-			goto out;
-		zero_user(page, zerofrom, len);
-		err = pagecache_write_end(file, mapping, curpos, len, len,
-						page, fsdata);
-		if (err < 0)
-			goto out;
-		BUG_ON(err != len);
-		err = 0;
-	}
-out:
-	return err;
-}
-
-/*
- * For moronic filesystems that do not allow holes in file.
- * We may have to extend the file.
- */
-int cont_write_begin(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned flags,
-			struct page **pagep, void **fsdata,
-			get_block_t *get_block, loff_t *bytes)
-{
-	struct inode *inode = mapping->host;
-	unsigned blocksize = 1 << inode->i_blkbits;
-	unsigned zerofrom;
-	int err;
-
-	err = cont_expand_zero(file, mapping, pos, bytes);
-	if (err)
-		return err;
-
-	zerofrom = *bytes & ~PAGE_CACHE_MASK;
-	if (pos+len > *bytes && zerofrom & (blocksize-1)) {
-		*bytes |= (blocksize-1);
-		(*bytes)++;
-	}
-
-	return block_write_begin(mapping, pos, len, flags, pagep, get_block);
-}
-EXPORT_SYMBOL(cont_write_begin);
-
-int block_commit_write(struct page *page, unsigned from, unsigned to)
-{
-	struct inode *inode = page->mapping->host;
-	__block_commit_write(inode,page,from,to);
-	return 0;
-}
-EXPORT_SYMBOL(block_commit_write);
-
-/*
- * block_page_mkwrite() is not allowed to change the file size as it gets
- * called from a page fault handler when a page is first dirtied. Hence we must
- * be careful to check for EOF conditions here. We set the page up correctly
- * for a written page which means we get ENOSPC checking when writing into
- * holes and correct delalloc and unwritten extent mapping on filesystems that
- * support these features.
- *
- * We are not allowed to take the i_mutex here so we have to play games to
- * protect against truncate races as the page could now be beyond EOF.  Because
- * truncate writes the inode size before removing pages, once we have the
- * page lock we can determine safely if the page is beyond EOF. If it is not
- * beyond EOF, then the page is guaranteed safe against truncation until we
- * unlock the page.
- *
- * Direct callers of this function should call vfs_check_frozen() so that page
- * fault does not busyloop until the fs is thawed.
- */
-int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
-			 get_block_t get_block)
-{
-	struct page *page = vmf->page;
-	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
-	unsigned long end;
-	loff_t size;
-	int ret;
-
-	lock_page(page);
-	size = i_size_read(inode);
-	if ((page->mapping != inode->i_mapping) ||
-	    (page_offset(page) > size)) {
-		/* We overload EFAULT to mean page got truncated */
-		ret = -EFAULT;
-		goto out_unlock;
-	}
-
-	/* page is wholly or partially inside EOF */
-	if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
-		end = size & ~PAGE_CACHE_MASK;
-	else
-		end = PAGE_CACHE_SIZE;
-
-	ret = __block_write_begin(page, 0, end, get_block);
-	if (!ret)
-		ret = block_commit_write(page, 0, end);
-
-	if (unlikely(ret < 0))
-		goto out_unlock;
-	/*
-	 * Freezing in progress? We check after the page is marked dirty and
-	 * with page lock held so if the test here fails, we are sure freezing
-	 * code will wait during syncing until the page fault is done - at that
-	 * point page will be dirty and unlocked so freezing code will write it
-	 * and writeprotect it again.
-	 */
-	set_page_dirty(page);
-	if (inode->i_sb->s_frozen != SB_UNFROZEN) {
-		ret = -EAGAIN;
-		goto out_unlock;
-	}
-	wait_on_page_writeback(page);
-	return 0;
-out_unlock:
-	unlock_page(page);
-	return ret;
-}
-EXPORT_SYMBOL(__block_page_mkwrite);
-
-int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
-		   get_block_t get_block)
-{
-	int ret;
-	struct super_block *sb = vma->vm_file->f_path.dentry->d_inode->i_sb;
-
-	/*
-	 * This check is racy but catches the common case. The check in
-	 * __block_page_mkwrite() is reliable.
-	 */
-	vfs_check_frozen(sb, SB_FREEZE_WRITE);
-	ret = __block_page_mkwrite(vma, vmf, get_block);
-	return block_page_mkwrite_return(ret);
-}
-EXPORT_SYMBOL(block_page_mkwrite);
-
-/*
- * nobh_write_begin()'s prereads are special: the buffer_heads are freed
- * immediately, while under the page lock.  So it needs a special end_io
- * handler which does not touch the bh after unlocking it.
- */
-static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
-{
-	__end_buffer_read_notouch(bh, uptodate);
-}
-
-/*
- * Attach the singly-linked list of buffers created by nobh_write_begin, to
- * the page (converting it to circular linked list and taking care of page
- * dirty races).
- */
-static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
-{
-	struct buffer_head *bh;
-
-	BUG_ON(!PageLocked(page));
-
-	spin_lock(&page->mapping->private_lock);
-	bh = head;
-	do {
-		if (PageDirty(page))
-			set_buffer_dirty(bh);
-		if (!bh->b_this_page)
-			bh->b_this_page = head;
-		bh = bh->b_this_page;
-	} while (bh != head);
-	attach_page_buffers(page, head);
-	spin_unlock(&page->mapping->private_lock);
-}
-
-/*
- * On entry, the page is fully not uptodate.
- * On exit the page is fully uptodate in the areas outside (from,to)
- * The filesystem needs to handle block truncation upon failure.
- */
-int nobh_write_begin(struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned flags,
-			struct page **pagep, void **fsdata,
-			get_block_t *get_block)
-{
-	struct inode *inode = mapping->host;
-	const unsigned blkbits = inode->i_blkbits;
-	const unsigned blocksize = 1 << blkbits;
-	struct buffer_head *head, *bh;
-	struct page *page;
-	pgoff_t index;
-	unsigned from, to;
-	unsigned block_in_page;
-	unsigned block_start, block_end;
-	sector_t block_in_file;
-	int nr_reads = 0;
-	int ret = 0;
-	int is_mapped_to_disk = 1;
-
-	index = pos >> PAGE_CACHE_SHIFT;
-	from = pos & (PAGE_CACHE_SIZE - 1);
-	to = from + len;
-
-	page = grab_cache_page_write_begin(mapping, index, flags);
-	if (!page)
-		return -ENOMEM;
-	*pagep = page;
-	*fsdata = NULL;
-
-	if (page_has_buffers(page)) {
-		ret = __block_write_begin(page, pos, len, get_block);
-		if (unlikely(ret))
-			goto out_release;
-		return ret;
-	}
-
-	if (PageMappedToDisk(page))
-		return 0;
-
-	/*
-	 * Allocate buffers so that we can keep track of state, and potentially
-	 * attach them to the page if an error occurs. In the common case of
-	 * no error, they will just be freed again without ever being attached
-	 * to the page (which is all OK, because we're under the page lock).
-	 *
-	 * Be careful: the buffer linked list is a NULL terminated one, rather
-	 * than the circular one we're used to.
-	 */
-	head = alloc_page_buffers(page, blocksize, 0);
-	if (!head) {
-		ret = -ENOMEM;
-		goto out_release;
-	}
-
-	block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
-
-	/*
-	 * We loop across all blocks in the page, whether or not they are
-	 * part of the affected region.  This is so we can discover if the
-	 * page is fully mapped-to-disk.
-	 */
-	for (block_start = 0, block_in_page = 0, bh = head;
-		  block_start < PAGE_CACHE_SIZE;
-		  block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
-		int create;
-
-		block_end = block_start + blocksize;
-		bh->b_state = 0;
-		create = 1;
-		if (block_start >= to)
-			create = 0;
-		ret = get_block(inode, block_in_file + block_in_page,
-					bh, create);
-		if (ret)
-			goto failed;
-		if (!buffer_mapped(bh))
-			is_mapped_to_disk = 0;
-		if (buffer_new(bh))
-			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
-		if (PageUptodate(page)) {
-			set_buffer_uptodate(bh);
-			continue;
-		}
-		if (buffer_new(bh) || !buffer_mapped(bh)) {
-			zero_user_segments(page, block_start, from,
-							to, block_end);
-			continue;
-		}
-		if (buffer_uptodate(bh))
-			continue;	/* reiserfs does this */
-		if (block_start < from || block_end > to) {
-			lock_buffer(bh);
-			bh->b_end_io = end_buffer_read_nobh;
-			submit_bh(READ, bh);
-			nr_reads++;
-		}
-	}
-
-	if (nr_reads) {
-		/*
-		 * The page is locked, so these buffers are protected from
-		 * any VM or truncate activity.  Hence we don't need to care
-		 * for the buffer_head refcounts.
-		 */
-		for (bh = head; bh; bh = bh->b_this_page) {
-			wait_on_buffer(bh);
-			if (!buffer_uptodate(bh))
-				ret = -EIO;
-		}
-		if (ret)
-			goto failed;
-	}
-
-	if (is_mapped_to_disk)
-		SetPageMappedToDisk(page);
-
-	*fsdata = head; /* to be released by nobh_write_end */
-
-	return 0;
-
-failed:
-	BUG_ON(!ret);
-	/*
-	 * Error recovery is a bit difficult. We need to zero out blocks that
-	 * were newly allocated, and dirty them to ensure they get written out.
-	 * Buffers need to be attached to the page at this point, otherwise
-	 * the handling of potential IO errors during writeout would be hard
-	 * (could try doing synchronous writeout, but what if that fails too?)
-	 */
-	attach_nobh_buffers(page, head);
-	page_zero_new_buffers(page, from, to);
-
-out_release:
-	unlock_page(page);
-	page_cache_release(page);
-	*pagep = NULL;
-
-	return ret;
-}
-EXPORT_SYMBOL(nobh_write_begin);
-
-int nobh_write_end(struct file *file, struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned copied,
-			struct page *page, void *fsdata)
-{
-	struct inode *inode = page->mapping->host;
-	struct buffer_head *head = fsdata;
-	struct buffer_head *bh;
-	BUG_ON(fsdata != NULL && page_has_buffers(page));
-
-	if (unlikely(copied < len) && head)
-		attach_nobh_buffers(page, head);
-	if (page_has_buffers(page))
-		return generic_write_end(file, mapping, pos, len,
-					copied, page, fsdata);
-
-	SetPageUptodate(page);
-	set_page_dirty(page);
-	if (pos+copied > inode->i_size) {
-		i_size_write(inode, pos+copied);
-		mark_inode_dirty(inode);
-	}
-
-	unlock_page(page);
-	page_cache_release(page);
-
-	while (head) {
-		bh = head;
-		head = head->b_this_page;
-		free_buffer_head(bh);
-	}
-
-	return copied;
-}
-EXPORT_SYMBOL(nobh_write_end);
-
-/*
- * nobh_writepage() - based on block_full_write_page() except
- * that it tries to operate without attaching bufferheads to
- * the page.
- */
-int nobh_writepage(struct page *page, get_block_t *get_block,
-			struct writeback_control *wbc)
-{
-	struct inode * const inode = page->mapping->host;
-	loff_t i_size = i_size_read(inode);
-	const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
-	unsigned offset;
-	int ret;
-
-	/* Is the page fully inside i_size? */
-	if (page->index < end_index)
-		goto out;
-
-	/* Is the page fully outside i_size? (truncate in progress) */
-	offset = i_size & (PAGE_CACHE_SIZE-1);
-	if (page->index >= end_index+1 || !offset) {
-		/*
-		 * The page may have dirty, unmapped buffers.  For example,
-		 * they may have been added in ext3_writepage().  Make them
-		 * freeable here, so the page does not leak.
-		 */
-#if 0
-		/* Not really sure about this  - do we need this ? */
-		if (page->mapping->a_ops->invalidatepage)
-			page->mapping->a_ops->invalidatepage(page, offset);
-#endif
-		unlock_page(page);
-		return 0; /* don't care */
-	}
-
-	/*
-	 * The page straddles i_size.  It must be zeroed out on each and every
-	 * writepage invocation because it may be mmapped.  "A file is mapped
-	 * in multiples of the page size.  For a file that is not a multiple of
-	 * the  page size, the remaining memory is zeroed when mapped, and
-	 * writes to that region are not written out to the file."
-	 */
-	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
-out:
-	ret = mpage_writepage(page, get_block, wbc);
-	if (ret == -EAGAIN)
-		ret = __block_write_full_page(inode, page, get_block, wbc,
-					      end_buffer_async_write);
-	return ret;
-}
-EXPORT_SYMBOL(nobh_writepage);
-
-int nobh_truncate_page(struct address_space *mapping,
-			loff_t from, get_block_t *get_block)
-{
-	pgoff_t index = from >> PAGE_CACHE_SHIFT;
-	unsigned offset = from & (PAGE_CACHE_SIZE-1);
-	unsigned blocksize;
-	sector_t iblock;
-	unsigned length, pos;
-	struct inode *inode = mapping->host;
-	struct page *page;
-	struct buffer_head map_bh;
-	int err;
-
-	blocksize = 1 << inode->i_blkbits;
-	length = offset & (blocksize - 1);
-
-	/* Block boundary? Nothing to do */
-	if (!length)
-		return 0;
-
-	length = blocksize - length;
-	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-
-	page = grab_cache_page(mapping, index);
-	err = -ENOMEM;
-	if (!page)
-		goto out;
-
-	if (page_has_buffers(page)) {
-has_buffers:
-		unlock_page(page);
-		page_cache_release(page);
-		return block_truncate_page(mapping, from, get_block);
-	}
-
-	/* Find the buffer that contains "offset" */
-	pos = blocksize;
-	while (offset >= pos) {
-		iblock++;
-		pos += blocksize;
-	}
-
-	map_bh.b_size = blocksize;
-	map_bh.b_state = 0;
-	err = get_block(inode, iblock, &map_bh, 0);
-	if (err)
-		goto unlock;
-	/* unmapped? It's a hole - nothing to do */
-	if (!buffer_mapped(&map_bh))
-		goto unlock;
-
-	/* Ok, it's mapped. Make sure it's up-to-date */
-	if (!PageUptodate(page)) {
-		err = mapping->a_ops->readpage(NULL, page);
-		if (err) {
-			page_cache_release(page);
-			goto out;
-		}
-		lock_page(page);
-		if (!PageUptodate(page)) {
-			err = -EIO;
-			goto unlock;
-		}
-		if (page_has_buffers(page))
-			goto has_buffers;
-	}
-	zero_user(page, offset, length);
-	set_page_dirty(page);
-	err = 0;
-
-unlock:
-	unlock_page(page);
-	page_cache_release(page);
-out:
-	return err;
-}
-EXPORT_SYMBOL(nobh_truncate_page);
-
-int block_truncate_page(struct address_space *mapping,
-			loff_t from, get_block_t *get_block)
-{
-	pgoff_t index = from >> PAGE_CACHE_SHIFT;
-	unsigned offset = from & (PAGE_CACHE_SIZE-1);
-	unsigned blocksize;
-	sector_t iblock;
-	unsigned length, pos;
-	struct inode *inode = mapping->host;
-	struct page *page;
-	struct buffer_head *bh;
-	int err;
-
-	blocksize = 1 << inode->i_blkbits;
-	length = offset & (blocksize - 1);
-
-	/* Block boundary? Nothing to do */
-	if (!length)
-		return 0;
-
-	length = blocksize - length;
-	iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-	
-	page = grab_cache_page(mapping, index);
-	err = -ENOMEM;
-	if (!page)
-		goto out;
-
-	if (!page_has_buffers(page))
-		create_empty_buffers(page, blocksize, 0);
-
-	/* Find the buffer that contains "offset" */
-	bh = page_buffers(page);
-	pos = blocksize;
-	while (offset >= pos) {
-		bh = bh->b_this_page;
-		iblock++;
-		pos += blocksize;
-	}
-
-	err = 0;
-	if (!buffer_mapped(bh)) {
-		WARN_ON(bh->b_size != blocksize);
-		err = get_block(inode, iblock, bh, 0);
-		if (err)
-			goto unlock;
-		/* unmapped? It's a hole - nothing to do */
-		if (!buffer_mapped(bh))
-			goto unlock;
-	}
-
-	/* Ok, it's mapped. Make sure it's up-to-date */
-	if (PageUptodate(page))
-		set_buffer_uptodate(bh);
-
-	if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
-		err = -EIO;
-		ll_rw_block(READ, 1, &bh);
-		wait_on_buffer(bh);
-		/* Uhhuh. Read error. Complain and punt. */
-		if (!buffer_uptodate(bh))
-			goto unlock;
-	}
-
-	zero_user(page, offset, length);
-	mark_buffer_dirty(bh);
-	err = 0;
-
-unlock:
-	unlock_page(page);
-	page_cache_release(page);
-out:
-	return err;
-}
-EXPORT_SYMBOL(block_truncate_page);
-
-/*
- * The generic ->writepage function for buffer-backed address_spaces
- * this form passes in the end_io handler used to finish the IO.
- */
-int block_write_full_page_endio(struct page *page, get_block_t *get_block,
-			struct writeback_control *wbc, bh_end_io_t *handler)
-{
-	struct inode * const inode = page->mapping->host;
-	loff_t i_size = i_size_read(inode);
-	const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
-	unsigned offset;
-
-	/* Is the page fully inside i_size? */
-	if (page->index < end_index)
-		return __block_write_full_page(inode, page, get_block, wbc,
-					       handler);
-
-	/* Is the page fully outside i_size? (truncate in progress) */
-	offset = i_size & (PAGE_CACHE_SIZE-1);
-	if (page->index >= end_index+1 || !offset) {
-		/*
-		 * The page may have dirty, unmapped buffers.  For example,
-		 * they may have been added in ext3_writepage().  Make them
-		 * freeable here, so the page does not leak.
-		 */
-		do_invalidatepage(page, 0);
-		unlock_page(page);
-		return 0; /* don't care */
-	}
-
-	/*
-	 * The page straddles i_size.  It must be zeroed out on each and every
-	 * writepage invocation because it may be mmapped.  "A file is mapped
-	 * in multiples of the page size.  For a file that is not a multiple of
-	 * the  page size, the remaining memory is zeroed when mapped, and
-	 * writes to that region are not written out to the file."
-	 */
-	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
-	return __block_write_full_page(inode, page, get_block, wbc, handler);
-}
-EXPORT_SYMBOL(block_write_full_page_endio);
-
-/*
- * The generic ->writepage function for buffer-backed address_spaces
- */
-int block_write_full_page(struct page *page, get_block_t *get_block,
-			struct writeback_control *wbc)
-{
-	return block_write_full_page_endio(page, get_block, wbc,
-					   end_buffer_async_write);
-}
-EXPORT_SYMBOL(block_write_full_page);
-
-sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
-			    get_block_t *get_block)
-{
-	struct buffer_head tmp;
-	struct inode *inode = mapping->host;
-	tmp.b_state = 0;
-	tmp.b_blocknr = 0;
-	tmp.b_size = 1 << inode->i_blkbits;
-	get_block(inode, block, &tmp, 0);
-	return tmp.b_blocknr;
-}
-EXPORT_SYMBOL(generic_block_bmap);
-
-static void end_bio_bh_io_sync(struct bio *bio, int err)
-{
-	struct buffer_head *bh = bio->bi_private;
-
-	if (err == -EOPNOTSUPP) {
-		set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
-	}
-
-	if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
-		set_bit(BH_Quiet, &bh->b_state);
-
-	bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
-	bio_put(bio);
-}
-
-int submit_bh(int rw, struct buffer_head * bh)
-{
-	struct bio *bio;
-	int ret = 0;
-
-	BUG_ON(!buffer_locked(bh));
-	BUG_ON(!buffer_mapped(bh));
-	BUG_ON(!bh->b_end_io);
-	BUG_ON(buffer_delay(bh));
-	BUG_ON(buffer_unwritten(bh));
-
-	/*
-	 * Only clear out a write error when rewriting
-	 */
-	if (test_set_buffer_req(bh) && (rw & WRITE))
-		clear_buffer_write_io_error(bh);
-
-	/*
-	 * from here on down, it's all bio -- do the initial mapping,
-	 * submit_bio -> generic_make_request may further map this bio around
-	 */
-	bio = bio_alloc(GFP_NOIO, 1);
-
-	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
-	bio->bi_bdev = bh->b_bdev;
-	bio->bi_io_vec[0].bv_page = bh->b_page;
-	bio->bi_io_vec[0].bv_len = bh->b_size;
-	bio->bi_io_vec[0].bv_offset = bh_offset(bh);
-
-	bio->bi_vcnt = 1;
-	bio->bi_idx = 0;
-	bio->bi_size = bh->b_size;
-
-	bio->bi_end_io = end_bio_bh_io_sync;
-	bio->bi_private = bh;
-
-	bio_get(bio);
-	submit_bio(rw, bio);
-
-	if (bio_flagged(bio, BIO_EOPNOTSUPP))
-		ret = -EOPNOTSUPP;
-
-	bio_put(bio);
-	return ret;
-}
-EXPORT_SYMBOL(submit_bh);
-
-/**
- * ll_rw_block: low-level access to block devices (DEPRECATED)
- * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
- * @nr: number of &struct buffer_heads in the array
- * @bhs: array of pointers to &struct buffer_head
- *
- * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
- * requests an I/O operation on them, either a %READ or a %WRITE.  The third
- * %READA option is described in the documentation for generic_make_request()
- * which ll_rw_block() calls.
- *
- * This function drops any buffer that it cannot get a lock on (with the
- * BH_Lock state bit), any buffer that appears to be clean when doing a write
- * request, and any buffer that appears to be up-to-date when doing read
- * request.  Further it marks as clean buffers that are processed for
- * writing (the buffer cache won't assume that they are actually clean
- * until the buffer gets unlocked).
- *
- * ll_rw_block sets b_end_io to simple completion handler that marks
- * the buffer up-to-date (if approriate), unlocks the buffer and wakes
- * any waiters. 
- *
- * All of the buffers must be for the same device, and must also be a
- * multiple of the current approved size for the device.
- */
-void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
-{
-	int i;
-
-	for (i = 0; i < nr; i++) {
-		struct buffer_head *bh = bhs[i];
-
-		if (!trylock_buffer(bh))
-			continue;
-		if (rw == WRITE) {
-			if (test_clear_buffer_dirty(bh)) {
-				bh->b_end_io = end_buffer_write_sync;
-				get_bh(bh);
-				submit_bh(WRITE, bh);
-				continue;
-			}
-		} else {
-			if (!buffer_uptodate(bh)) {
-				bh->b_end_io = end_buffer_read_sync;
-				get_bh(bh);
-				submit_bh(rw, bh);
-				continue;
-			}
-		}
-		unlock_buffer(bh);
-	}
-}
-EXPORT_SYMBOL(ll_rw_block);
-
-void write_dirty_buffer(struct buffer_head *bh, int rw)
-{
-	lock_buffer(bh);
-	if (!test_clear_buffer_dirty(bh)) {
-		unlock_buffer(bh);
-		return;
-	}
-	bh->b_end_io = end_buffer_write_sync;
-	get_bh(bh);
-	submit_bh(rw, bh);
-}
-EXPORT_SYMBOL(write_dirty_buffer);
-
-/*
- * For a data-integrity writeout, we need to wait upon any in-progress I/O
- * and then start new I/O and then wait upon it.  The caller must have a ref on
- * the buffer_head.
- */
-int __sync_dirty_buffer(struct buffer_head *bh, int rw)
-{
-	int ret = 0;
-
-	WARN_ON(atomic_read(&bh->b_count) < 1);
-	lock_buffer(bh);
-	if (test_clear_buffer_dirty(bh)) {
-		get_bh(bh);
-		bh->b_end_io = end_buffer_write_sync;
-		ret = submit_bh(rw, bh);
-		wait_on_buffer(bh);
-		if (!ret && !buffer_uptodate(bh))
-			ret = -EIO;
-	} else {
-		unlock_buffer(bh);
-	}
-	return ret;
-}
-EXPORT_SYMBOL(__sync_dirty_buffer);
-
-int sync_dirty_buffer(struct buffer_head *bh)
-{
-	return __sync_dirty_buffer(bh, WRITE_SYNC);
-}
-EXPORT_SYMBOL(sync_dirty_buffer);
-
-/*
- * try_to_free_buffers() checks if all the buffers on this particular page
- * are unused, and releases them if so.
- *
- * Exclusion against try_to_free_buffers may be obtained by either
- * locking the page or by holding its mapping's private_lock.
- *
- * If the page is dirty but all the buffers are clean then we need to
- * be sure to mark the page clean as well.  This is because the page
- * may be against a block device, and a later reattachment of buffers
- * to a dirty page will set *all* buffers dirty.  Which would corrupt
- * filesystem data on the same device.
- *
- * The same applies to regular filesystem pages: if all the buffers are
- * clean then we set the page clean and proceed.  To do that, we require
- * total exclusion from __set_page_dirty_buffers().  That is obtained with
- * private_lock.
- *
- * try_to_free_buffers() is non-blocking.
- */
-static inline int buffer_busy(struct buffer_head *bh)
-{
-	return atomic_read(&bh->b_count) |
-		(bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
-}
-
-static int
-drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
-{
-	struct buffer_head *head = page_buffers(page);
-	struct buffer_head *bh;
-
-	bh = head;
-	do {
-		if (buffer_write_io_error(bh) && page->mapping)
-			set_bit(AS_EIO, &page->mapping->flags);
-		if (buffer_busy(bh))
-			goto failed;
-		bh = bh->b_this_page;
-	} while (bh != head);
-
-	do {
-		struct buffer_head *next = bh->b_this_page;
-
-		if (bh->b_assoc_map)
-			__remove_assoc_queue(bh);
-		bh = next;
-	} while (bh != head);
-	*buffers_to_free = head;
-	__clear_page_buffers(page);
-	return 1;
-failed:
-	return 0;
-}
-
-int try_to_free_buffers(struct page *page)
-{
-	struct address_space * const mapping = page->mapping;
-	struct buffer_head *buffers_to_free = NULL;
-	int ret = 0;
-
-	BUG_ON(!PageLocked(page));
-	if (PageWriteback(page))
-		return 0;
-
-	if (mapping == NULL) {		/* can this still happen? */
-		ret = drop_buffers(page, &buffers_to_free);
-		goto out;
-	}
-
-	spin_lock(&mapping->private_lock);
-	ret = drop_buffers(page, &buffers_to_free);
-
-	/*
-	 * If the filesystem writes its buffers by hand (eg ext3)
-	 * then we can have clean buffers against a dirty page.  We
-	 * clean the page here; otherwise the VM will never notice
-	 * that the filesystem did any IO at all.
-	 *
-	 * Also, during truncate, discard_buffer will have marked all
-	 * the page's buffers clean.  We discover that here and clean
-	 * the page also.
-	 *
-	 * private_lock must be held over this entire operation in order
-	 * to synchronise against __set_page_dirty_buffers and prevent the
-	 * dirty bit from being lost.
-	 */
-	if (ret)
-		cancel_dirty_page(page, PAGE_CACHE_SIZE);
-	spin_unlock(&mapping->private_lock);
-out:
-	if (buffers_to_free) {
-		struct buffer_head *bh = buffers_to_free;
-
-		do {
-			struct buffer_head *next = bh->b_this_page;
-			free_buffer_head(bh);
-			bh = next;
-		} while (bh != buffers_to_free);
-	}
-	return ret;
-}
-EXPORT_SYMBOL(try_to_free_buffers);
-
-/*
- * There are no bdflush tunables left.  But distributions are
- * still running obsolete flush daemons, so we terminate them here.
- *
- * Use of bdflush() is deprecated and will be removed in a future kernel.
- * The `flush-X' kernel threads fully replace bdflush daemons and this call.
- */
-SYSCALL_DEFINE2(bdflush, int, func, long, data)
-{
-	static int msg_count;
-
-	if (!capable(CAP_SYS_ADMIN))
-		return -EPERM;
-
-	if (msg_count < 5) {
-		msg_count++;
-		printk(KERN_INFO
-			"warning: process `%s' used the obsolete bdflush"
-			" system call\n", current->comm);
-		printk(KERN_INFO "Fix your initscripts?\n");
-	}
-
-	if (func == 1)
-		do_exit(0);
-	return 0;
-}
-
-/*
- * Buffer-head allocation
- */
-static struct kmem_cache *bh_cachep;
-
-/*
- * Once the number of bh's in the machine exceeds this level, we start
- * stripping them in writeback.
- */
-static int max_buffer_heads;
-
-int buffer_heads_over_limit;
-
-struct bh_accounting {
-	int nr;			/* Number of live bh's */
-	int ratelimit;		/* Limit cacheline bouncing */
-};
-
-static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
-
-static void recalc_bh_state(void)
-{
-	int i;
-	int tot = 0;
-
-	if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
-		return;
-	__this_cpu_write(bh_accounting.ratelimit, 0);
-	for_each_online_cpu(i)
-		tot += per_cpu(bh_accounting, i).nr;
-	buffer_heads_over_limit = (tot > max_buffer_heads);
-}
-
-struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
-{
-	struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
-	if (ret) {
-		INIT_LIST_HEAD(&ret->b_assoc_buffers);
-		preempt_disable();
-		__this_cpu_inc(bh_accounting.nr);
-		recalc_bh_state();
-		preempt_enable();
-	}
-	return ret;
-}
-EXPORT_SYMBOL(alloc_buffer_head);
-
-void free_buffer_head(struct buffer_head *bh)
-{
-	BUG_ON(!list_empty(&bh->b_assoc_buffers));
-	kmem_cache_free(bh_cachep, bh);
-	preempt_disable();
-	__this_cpu_dec(bh_accounting.nr);
-	recalc_bh_state();
-	preempt_enable();
-}
-EXPORT_SYMBOL(free_buffer_head);
-
-static void buffer_exit_cpu(int cpu)
-{
-	int i;
-	struct bh_lru *b = &per_cpu(bh_lrus, cpu);
-
-	for (i = 0; i < BH_LRU_SIZE; i++) {
-		brelse(b->bhs[i]);
-		b->bhs[i] = NULL;
-	}
-	this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
-	per_cpu(bh_accounting, cpu).nr = 0;
-}
-
-static int buffer_cpu_notify(struct notifier_block *self,
-			      unsigned long action, void *hcpu)
-{
-	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
-		buffer_exit_cpu((unsigned long)hcpu);
-	return NOTIFY_OK;
-}
-
-/**
- * bh_uptodate_or_lock - Test whether the buffer is uptodate
- * @bh: struct buffer_head
- *
- * Return true if the buffer is up-to-date and false,
- * with the buffer locked, if not.
- */
-int bh_uptodate_or_lock(struct buffer_head *bh)
-{
-	if (!buffer_uptodate(bh)) {
-		lock_buffer(bh);
-		if (!buffer_uptodate(bh))
-			return 0;
-		unlock_buffer(bh);
-	}
-	return 1;
-}
-EXPORT_SYMBOL(bh_uptodate_or_lock);
-
-/**
- * bh_submit_read - Submit a locked buffer for reading
- * @bh: struct buffer_head
- *
- * Returns zero on success and -EIO on error.
- */
-int bh_submit_read(struct buffer_head *bh)
-{
-	BUG_ON(!buffer_locked(bh));
-
-	if (buffer_uptodate(bh)) {
-		unlock_buffer(bh);
-		return 0;
-	}
-
-	get_bh(bh);
-	bh->b_end_io = end_buffer_read_sync;
-	submit_bh(READ, bh);
-	wait_on_buffer(bh);
-	if (buffer_uptodate(bh))
-		return 0;
-	return -EIO;
-}
-EXPORT_SYMBOL(bh_submit_read);
-
-void __init buffer_init(void)
-{
-	int nrpages;
-
-	bh_cachep = kmem_cache_create("buffer_head",
-			sizeof(struct buffer_head), 0,
-				(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
-				SLAB_MEM_SPREAD),
-				NULL);
-
-	/*
-	 * Limit the bh occupancy to 10% of ZONE_NORMAL
-	 */
-	nrpages = (nr_free_buffer_pages() * 10) / 100;
-	max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
-	hotcpu_notifier(buffer_cpu_notify, 0);
-}