Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable: (864 commits)
  Btrfs: explicitly mark the tree log root for writeback
  Btrfs: Drop the hardware crc32c asm code
  Btrfs: Add Documentation/filesystem/btrfs.txt, remove old COPYING
  Btrfs: kmap_atomic(KM_USER0) is safe for btrfs_readpage_end_io_hook
  Btrfs: Don't use kmap_atomic(..., KM_IRQ0) during checksum verifies
  Btrfs: tree logging checksum fixes
  Btrfs: don't change file extent's ram_bytes in btrfs_drop_extents
  Btrfs: Use btrfs_join_transaction to avoid deadlocks during snapshot creation
  Btrfs: drop remaining LINUX_KERNEL_VERSION checks and compat code
  Btrfs: drop EXPORT symbols from extent_io.c
  Btrfs: Fix checkpatch.pl warnings
  Btrfs: Fix free block discard calls down to the block layer
  Btrfs: avoid orphan inode caused by log replay
  Btrfs: avoid potential super block corruption
  Btrfs: do not call kfree if kmalloc failed in btrfs_sysfs_add_super
  Btrfs: fix a memory leak in btrfs_get_sb
  Btrfs: Fix typo in clear_state_cb
  Btrfs: Fix memset length in btrfs_file_write
  Btrfs: update directory's size when creating subvol/snapshot
  Btrfs: add permission checks to the ioctls
  ...

1 files changed, 2343 insertions, 0 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
new file mode 100644
index 000000000000..81a313874ae5
--- /dev/null
+++ b/fs/btrfs/disk-io.c
@@ -0,0 +1,2343 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/version.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/scatterlist.h>
+#include <linux/swap.h>
+#include <linux/radix-tree.h>
+#include <linux/writeback.h>
+#include <linux/buffer_head.h>
+#include <linux/workqueue.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+#include "compat.h"
+#include "crc32c.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "volumes.h"
+#include "print-tree.h"
+#include "async-thread.h"
+#include "locking.h"
+#include "ref-cache.h"
+#include "tree-log.h"
+
+static struct extent_io_ops btree_extent_io_ops;
+static void end_workqueue_fn(struct btrfs_work *work);
+
+/*
+ * end_io_wq structs are used to do processing in task context when an IO is
+ * complete.  This is used during reads to verify checksums, and it is used
+ * by writes to insert metadata for new file extents after IO is complete.
+ */
+struct end_io_wq {
+	struct bio *bio;
+	bio_end_io_t *end_io;
+	void *private;
+	struct btrfs_fs_info *info;
+	int error;
+	int metadata;
+	struct list_head list;
+	struct btrfs_work work;
+};
+
+/*
+ * async submit bios are used to offload expensive checksumming
+ * onto the worker threads.  They checksum file and metadata bios
+ * just before they are sent down the IO stack.
+ */
+struct async_submit_bio {
+	struct inode *inode;
+	struct bio *bio;
+	struct list_head list;
+	extent_submit_bio_hook_t *submit_bio_start;
+	extent_submit_bio_hook_t *submit_bio_done;
+	int rw;
+	int mirror_num;
+	unsigned long bio_flags;
+	struct btrfs_work work;
+};
+
+/*
+ * extents on the btree inode are pretty simple, there's one extent
+ * that covers the entire device
+ */
+static struct extent_map *btree_get_extent(struct inode *inode,
+		struct page *page, size_t page_offset, u64 start, u64 len,
+		int create)
+{
+	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_map *em;
+	int ret;
+
+	spin_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, start, len);
+	if (em) {
+		em->bdev =
+			BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
+		spin_unlock(&em_tree->lock);
+		goto out;
+	}
+	spin_unlock(&em_tree->lock);
+
+	em = alloc_extent_map(GFP_NOFS);
+	if (!em) {
+		em = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+	em->start = 0;
+	em->len = (u64)-1;
+	em->block_len = (u64)-1;
+	em->block_start = 0;
+	em->bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
+
+	spin_lock(&em_tree->lock);
+	ret = add_extent_mapping(em_tree, em);
+	if (ret == -EEXIST) {
+		u64 failed_start = em->start;
+		u64 failed_len = em->len;
+
+		free_extent_map(em);
+		em = lookup_extent_mapping(em_tree, start, len);
+		if (em) {
+			ret = 0;
+		} else {
+			em = lookup_extent_mapping(em_tree, failed_start,
+						   failed_len);
+			ret = -EIO;
+		}
+	} else if (ret) {
+		free_extent_map(em);
+		em = NULL;
+	}
+	spin_unlock(&em_tree->lock);
+
+	if (ret)
+		em = ERR_PTR(ret);
+out:
+	return em;
+}
+
+u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len)
+{
+	return btrfs_crc32c(seed, data, len);
+}
+
+void btrfs_csum_final(u32 crc, char *result)
+{
+	*(__le32 *)result = ~cpu_to_le32(crc);
+}
+
+/*
+ * compute the csum for a btree block, and either verify it or write it
+ * into the csum field of the block.
+ */
+static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
+			   int verify)
+{
+	u16 csum_size =
+		btrfs_super_csum_size(&root->fs_info->super_copy);
+	char *result = NULL;
+	unsigned long len;
+	unsigned long cur_len;
+	unsigned long offset = BTRFS_CSUM_SIZE;
+	char *map_token = NULL;
+	char *kaddr;
+	unsigned long map_start;
+	unsigned long map_len;
+	int err;
+	u32 crc = ~(u32)0;
+	unsigned long inline_result;
+
+	len = buf->len - offset;
+	while (len > 0) {
+		err = map_private_extent_buffer(buf, offset, 32,
+					&map_token, &kaddr,
+					&map_start, &map_len, KM_USER0);
+		if (err)
+			return 1;
+		cur_len = min(len, map_len - (offset - map_start));
+		crc = btrfs_csum_data(root, kaddr + offset - map_start,
+				      crc, cur_len);
+		len -= cur_len;
+		offset += cur_len;
+		unmap_extent_buffer(buf, map_token, KM_USER0);
+	}
+	if (csum_size > sizeof(inline_result)) {
+		result = kzalloc(csum_size * sizeof(char), GFP_NOFS);
+		if (!result)
+			return 1;
+	} else {
+		result = (char *)&inline_result;
+	}
+
+	btrfs_csum_final(crc, result);
+
+	if (verify) {
+		if (memcmp_extent_buffer(buf, result, 0, csum_size)) {
+			u32 val;
+			u32 found = 0;
+			memcpy(&found, result, csum_size);
+
+			read_extent_buffer(buf, &val, 0, csum_size);
+			printk(KERN_INFO "btrfs: %s checksum verify failed "
+			       "on %llu wanted %X found %X level %d\n",
+			       root->fs_info->sb->s_id,
+			       buf->start, val, found, btrfs_header_level(buf));
+			if (result != (char *)&inline_result)
+				kfree(result);
+			return 1;
+		}
+	} else {
+		write_extent_buffer(buf, result, 0, csum_size);
+	}
+	if (result != (char *)&inline_result)
+		kfree(result);
+	return 0;
+}
+
+/*
+ * we can't consider a given block up to date unless the transid of the
+ * block matches the transid in the parent node's pointer.  This is how we
+ * detect blocks that either didn't get written at all or got written
+ * in the wrong place.
+ */
+static int verify_parent_transid(struct extent_io_tree *io_tree,
+				 struct extent_buffer *eb, u64 parent_transid)
+{
+	int ret;
+
+	if (!parent_transid || btrfs_header_generation(eb) == parent_transid)
+		return 0;
+
+	lock_extent(io_tree, eb->start, eb->start + eb->len - 1, GFP_NOFS);
+	if (extent_buffer_uptodate(io_tree, eb) &&
+	    btrfs_header_generation(eb) == parent_transid) {
+		ret = 0;
+		goto out;
+	}
+	printk("parent transid verify failed on %llu wanted %llu found %llu\n",
+	       (unsigned long long)eb->start,
+	       (unsigned long long)parent_transid,
+	       (unsigned long long)btrfs_header_generation(eb));
+	ret = 1;
+	clear_extent_buffer_uptodate(io_tree, eb);
+out:
+	unlock_extent(io_tree, eb->start, eb->start + eb->len - 1,
+		      GFP_NOFS);
+	return ret;
+}
+
+/*
+ * helper to read a given tree block, doing retries as required when
+ * the checksums don't match and we have alternate mirrors to try.
+ */
+static int btree_read_extent_buffer_pages(struct btrfs_root *root,
+					  struct extent_buffer *eb,
+					  u64 start, u64 parent_transid)
+{
+	struct extent_io_tree *io_tree;
+	int ret;
+	int num_copies = 0;
+	int mirror_num = 0;
+
+	io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
+	while (1) {
+		ret = read_extent_buffer_pages(io_tree, eb, start, 1,
+					       btree_get_extent, mirror_num);
+		if (!ret &&
+		    !verify_parent_transid(io_tree, eb, parent_transid))
+			return ret;
+
+		num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
+					      eb->start, eb->len);
+		if (num_copies == 1)
+			return ret;
+
+		mirror_num++;
+		if (mirror_num > num_copies)
+			return ret;
+	}
+	return -EIO;
+}
+
+/*
+ * checksum a dirty tree block before IO.  This has extra checks to make sure
+ * we only fill in the checksum field in the first page of a multi-page block
+ */
+
+static int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
+{
+	struct extent_io_tree *tree;
+	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 found_start;
+	int found_level;
+	unsigned long len;
+	struct extent_buffer *eb;
+	int ret;
+
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+
+	if (page->private == EXTENT_PAGE_PRIVATE)
+		goto out;
+	if (!page->private)
+		goto out;
+	len = page->private >> 2;
+	WARN_ON(len == 0);
+
+	eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
+	ret = btree_read_extent_buffer_pages(root, eb, start + PAGE_CACHE_SIZE,
+					     btrfs_header_generation(eb));
+	BUG_ON(ret);
+	found_start = btrfs_header_bytenr(eb);
+	if (found_start != start) {
+		WARN_ON(1);
+		goto err;
+	}
+	if (eb->first_page != page) {
+		WARN_ON(1);
+		goto err;
+	}
+	if (!PageUptodate(page)) {
+		WARN_ON(1);
+		goto err;
+	}
+	found_level = btrfs_header_level(eb);
+
+	csum_tree_block(root, eb, 0);
+err:
+	free_extent_buffer(eb);
+out:
+	return 0;
+}
+
+static int check_tree_block_fsid(struct btrfs_root *root,
+				 struct extent_buffer *eb)
+{
+	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+	u8 fsid[BTRFS_UUID_SIZE];
+	int ret = 1;
+
+	read_extent_buffer(eb, fsid, (unsigned long)btrfs_header_fsid(eb),
+			   BTRFS_FSID_SIZE);
+	while (fs_devices) {
+		if (!memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE)) {
+			ret = 0;
+			break;
+		}
+		fs_devices = fs_devices->seed;
+	}
+	return ret;
+}
+
+static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
+			       struct extent_state *state)
+{
+	struct extent_io_tree *tree;
+	u64 found_start;
+	int found_level;
+	unsigned long len;
+	struct extent_buffer *eb;
+	struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
+	int ret = 0;
+
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+	if (page->private == EXTENT_PAGE_PRIVATE)
+		goto out;
+	if (!page->private)
+		goto out;
+
+	len = page->private >> 2;
+	WARN_ON(len == 0);
+
+	eb = alloc_extent_buffer(tree, start, len, page, GFP_NOFS);
+
+	found_start = btrfs_header_bytenr(eb);
+	if (found_start != start) {
+		printk(KERN_INFO "btrfs bad tree block start %llu %llu\n",
+		       (unsigned long long)found_start,
+		       (unsigned long long)eb->start);
+		ret = -EIO;
+		goto err;
+	}
+	if (eb->first_page != page) {
+		printk(KERN_INFO "btrfs bad first page %lu %lu\n",
+		       eb->first_page->index, page->index);
+		WARN_ON(1);
+		ret = -EIO;
+		goto err;
+	}
+	if (check_tree_block_fsid(root, eb)) {
+		printk(KERN_INFO "btrfs bad fsid on block %llu\n",
+		       (unsigned long long)eb->start);
+		ret = -EIO;
+		goto err;
+	}
+	found_level = btrfs_header_level(eb);
+
+	ret = csum_tree_block(root, eb, 1);
+	if (ret)
+		ret = -EIO;
+
+	end = min_t(u64, eb->len, PAGE_CACHE_SIZE);
+	end = eb->start + end - 1;
+err:
+	free_extent_buffer(eb);
+out:
+	return ret;
+}
+
+static void end_workqueue_bio(struct bio *bio, int err)
+{
+	struct end_io_wq *end_io_wq = bio->bi_private;
+	struct btrfs_fs_info *fs_info;
+
+	fs_info = end_io_wq->info;
+	end_io_wq->error = err;
+	end_io_wq->work.func = end_workqueue_fn;
+	end_io_wq->work.flags = 0;
+
+	if (bio->bi_rw & (1 << BIO_RW)) {
+		if (end_io_wq->metadata)
+			btrfs_queue_worker(&fs_info->endio_meta_write_workers,
+					   &end_io_wq->work);
+		else
+			btrfs_queue_worker(&fs_info->endio_write_workers,
+					   &end_io_wq->work);
+	} else {
+		if (end_io_wq->metadata)
+			btrfs_queue_worker(&fs_info->endio_meta_workers,
+					   &end_io_wq->work);
+		else
+			btrfs_queue_worker(&fs_info->endio_workers,
+					   &end_io_wq->work);
+	}
+}
+
+int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
+			int metadata)
+{
+	struct end_io_wq *end_io_wq;
+	end_io_wq = kmalloc(sizeof(*end_io_wq), GFP_NOFS);
+	if (!end_io_wq)
+		return -ENOMEM;
+
+	end_io_wq->private = bio->bi_private;
+	end_io_wq->end_io = bio->bi_end_io;
+	end_io_wq->info = info;
+	end_io_wq->error = 0;
+	end_io_wq->bio = bio;
+	end_io_wq->metadata = metadata;
+
+	bio->bi_private = end_io_wq;
+	bio->bi_end_io = end_workqueue_bio;
+	return 0;
+}
+
+unsigned long btrfs_async_submit_limit(struct btrfs_fs_info *info)
+{
+	unsigned long limit = min_t(unsigned long,
+				    info->workers.max_workers,
+				    info->fs_devices->open_devices);
+	return 256 * limit;
+}
+
+int btrfs_congested_async(struct btrfs_fs_info *info, int iodone)
+{
+	return atomic_read(&info->nr_async_bios) >
+		btrfs_async_submit_limit(info);
+}
+
+static void run_one_async_start(struct btrfs_work *work)
+{
+	struct btrfs_fs_info *fs_info;
+	struct async_submit_bio *async;
+
+	async = container_of(work, struct  async_submit_bio, work);
+	fs_info = BTRFS_I(async->inode)->root->fs_info;
+	async->submit_bio_start(async->inode, async->rw, async->bio,
+			       async->mirror_num, async->bio_flags);
+}
+
+static void run_one_async_done(struct btrfs_work *work)
+{
+	struct btrfs_fs_info *fs_info;
+	struct async_submit_bio *async;
+	int limit;
+
+	async = container_of(work, struct  async_submit_bio, work);
+	fs_info = BTRFS_I(async->inode)->root->fs_info;
+
+	limit = btrfs_async_submit_limit(fs_info);
+	limit = limit * 2 / 3;
+
+	atomic_dec(&fs_info->nr_async_submits);
+
+	if (atomic_read(&fs_info->nr_async_submits) < limit &&
+	    waitqueue_active(&fs_info->async_submit_wait))
+		wake_up(&fs_info->async_submit_wait);
+
+	async->submit_bio_done(async->inode, async->rw, async->bio,
+			       async->mirror_num, async->bio_flags);
+}
+
+static void run_one_async_free(struct btrfs_work *work)
+{
+	struct async_submit_bio *async;
+
+	async = container_of(work, struct  async_submit_bio, work);
+	kfree(async);
+}
+
+int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
+			int rw, struct bio *bio, int mirror_num,
+			unsigned long bio_flags,
+			extent_submit_bio_hook_t *submit_bio_start,
+			extent_submit_bio_hook_t *submit_bio_done)
+{
+	struct async_submit_bio *async;
+
+	async = kmalloc(sizeof(*async), GFP_NOFS);
+	if (!async)
+		return -ENOMEM;
+
+	async->inode = inode;
+	async->rw = rw;
+	async->bio = bio;
+	async->mirror_num = mirror_num;
+	async->submit_bio_start = submit_bio_start;
+	async->submit_bio_done = submit_bio_done;
+
+	async->work.func = run_one_async_start;
+	async->work.ordered_func = run_one_async_done;
+	async->work.ordered_free = run_one_async_free;
+
+	async->work.flags = 0;
+	async->bio_flags = bio_flags;
+
+	atomic_inc(&fs_info->nr_async_submits);
+	btrfs_queue_worker(&fs_info->workers, &async->work);
+#if 0
+	int limit = btrfs_async_submit_limit(fs_info);
+	if (atomic_read(&fs_info->nr_async_submits) > limit) {
+		wait_event_timeout(fs_info->async_submit_wait,
+			   (atomic_read(&fs_info->nr_async_submits) < limit),
+			   HZ/10);
+
+		wait_event_timeout(fs_info->async_submit_wait,
+			   (atomic_read(&fs_info->nr_async_bios) < limit),
+			   HZ/10);
+	}
+#endif
+	while (atomic_read(&fs_info->async_submit_draining) &&
+	      atomic_read(&fs_info->nr_async_submits)) {
+		wait_event(fs_info->async_submit_wait,
+			   (atomic_read(&fs_info->nr_async_submits) == 0));
+	}
+
+	return 0;
+}
+
+static int btree_csum_one_bio(struct bio *bio)
+{
+	struct bio_vec *bvec = bio->bi_io_vec;
+	int bio_index = 0;
+	struct btrfs_root *root;
+
+	WARN_ON(bio->bi_vcnt <= 0);
+	while (bio_index < bio->bi_vcnt) {
+		root = BTRFS_I(bvec->bv_page->mapping->host)->root;
+		csum_dirty_buffer(root, bvec->bv_page);
+		bio_index++;
+		bvec++;
+	}
+	return 0;
+}
+
+static int __btree_submit_bio_start(struct inode *inode, int rw,
+				    struct bio *bio, int mirror_num,
+				    unsigned long bio_flags)
+{
+	/*
+	 * when we're called for a write, we're already in the async
+	 * submission context.  Just jump into btrfs_map_bio
+	 */
+	btree_csum_one_bio(bio);
+	return 0;
+}
+
+static int __btree_submit_bio_done(struct inode *inode, int rw, struct bio *bio,
+				 int mirror_num, unsigned long bio_flags)
+{
+	/*
+	 * when we're called for a write, we're already in the async
+	 * submission context.  Just jump into btrfs_map_bio
+	 */
+	return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 1);
+}
+
+static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
+				 int mirror_num, unsigned long bio_flags)
+{
+	int ret;
+
+	ret = btrfs_bio_wq_end_io(BTRFS_I(inode)->root->fs_info,
+					  bio, 1);
+	BUG_ON(ret);
+
+	if (!(rw & (1 << BIO_RW))) {
+		/*
+		 * called for a read, do the setup so that checksum validation
+		 * can happen in the async kernel threads
+		 */
+		return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio,
+				     mirror_num, 0);
+	}
+	/*
+	 * kthread helpers are used to submit writes so that checksumming
+	 * can happen in parallel across all CPUs
+	 */
+	return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info,
+				   inode, rw, bio, mirror_num, 0,
+				   __btree_submit_bio_start,
+				   __btree_submit_bio_done);
+}
+
+static int btree_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+
+	if (current->flags & PF_MEMALLOC) {
+		redirty_page_for_writepage(wbc, page);
+		unlock_page(page);
+		return 0;
+	}
+	return extent_write_full_page(tree, page, btree_get_extent, wbc);
+}
+
+static int btree_writepages(struct address_space *mapping,
+			    struct writeback_control *wbc)
+{
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(mapping->host)->io_tree;
+	if (wbc->sync_mode == WB_SYNC_NONE) {
+		u64 num_dirty;
+		u64 start = 0;
+		unsigned long thresh = 32 * 1024 * 1024;
+
+		if (wbc->for_kupdate)
+			return 0;
+
+		num_dirty = count_range_bits(tree, &start, (u64)-1,
+					     thresh, EXTENT_DIRTY);
+		if (num_dirty < thresh)
+			return 0;
+	}
+	return extent_writepages(tree, mapping, btree_get_extent, wbc);
+}
+
+static int btree_readpage(struct file *file, struct page *page)
+{
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+	return extent_read_full_page(tree, page, btree_get_extent);
+}
+
+static int btree_releasepage(struct page *page, gfp_t gfp_flags)
+{
+	struct extent_io_tree *tree;
+	struct extent_map_tree *map;
+	int ret;
+
+	if (PageWriteback(page) || PageDirty(page))
+		return 0;
+
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+	map = &BTRFS_I(page->mapping->host)->extent_tree;
+
+	ret = try_release_extent_state(map, tree, page, gfp_flags);
+	if (!ret)
+		return 0;
+
+	ret = try_release_extent_buffer(tree, page);
+	if (ret == 1) {
+		ClearPagePrivate(page);
+		set_page_private(page, 0);
+		page_cache_release(page);
+	}
+
+	return ret;
+}
+
+static void btree_invalidatepage(struct page *page, unsigned long offset)
+{
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+	extent_invalidatepage(tree, page, offset);
+	btree_releasepage(page, GFP_NOFS);
+	if (PagePrivate(page)) {
+		printk(KERN_WARNING "btrfs warning page private not zero "
+		       "on page %llu\n", (unsigned long long)page_offset(page));
+		ClearPagePrivate(page);
+		set_page_private(page, 0);
+		page_cache_release(page);
+	}
+}
+
+#if 0
+static int btree_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct buffer_head *bh;
+	struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
+	struct buffer_head *head;
+	if (!page_has_buffers(page)) {
+		create_empty_buffers(page, root->fs_info->sb->s_blocksize,
+					(1 << BH_Dirty)|(1 << BH_Uptodate));
+	}
+	head = page_buffers(page);
+	bh = head;
+	do {
+		if (buffer_dirty(bh))
+			csum_tree_block(root, bh, 0);
+		bh = bh->b_this_page;
+	} while (bh != head);
+	return block_write_full_page(page, btree_get_block, wbc);
+}
+#endif
+
+static struct address_space_operations btree_aops = {
+	.readpage	= btree_readpage,
+	.writepage	= btree_writepage,
+	.writepages	= btree_writepages,
+	.releasepage	= btree_releasepage,
+	.invalidatepage = btree_invalidatepage,
+	.sync_page	= block_sync_page,
+};
+
+int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
+			 u64 parent_transid)
+{
+	struct extent_buffer *buf = NULL;
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	int ret = 0;
+
+	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
+	if (!buf)
+		return 0;
+	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
+				 buf, 0, 0, btree_get_extent, 0);
+	free_extent_buffer(buf);
+	return ret;
+}
+
+struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
+					    u64 bytenr, u32 blocksize)
+{
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	struct extent_buffer *eb;
+	eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
+				bytenr, blocksize, GFP_NOFS);
+	return eb;
+}
+
+struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
+						 u64 bytenr, u32 blocksize)
+{
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	struct extent_buffer *eb;
+
+	eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
+				 bytenr, blocksize, NULL, GFP_NOFS);
+	return eb;
+}
+
+
+int btrfs_write_tree_block(struct extent_buffer *buf)
+{
+	return btrfs_fdatawrite_range(buf->first_page->mapping, buf->start,
+				      buf->start + buf->len - 1, WB_SYNC_ALL);
+}
+
+int btrfs_wait_tree_block_writeback(struct extent_buffer *buf)
+{
+	return btrfs_wait_on_page_writeback_range(buf->first_page->mapping,
+				  buf->start, buf->start + buf->len - 1);
+}
+
+struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
+				      u32 blocksize, u64 parent_transid)
+{
+	struct extent_buffer *buf = NULL;
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	struct extent_io_tree *io_tree;
+	int ret;
+
+	io_tree = &BTRFS_I(btree_inode)->io_tree;
+
+	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
+	if (!buf)
+		return NULL;
+
+	ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
+
+	if (ret == 0)
+		buf->flags |= EXTENT_UPTODATE;
+	else
+		WARN_ON(1);
+	return buf;
+
+}
+
+int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		     struct extent_buffer *buf)
+{
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	if (btrfs_header_generation(buf) ==
+	    root->fs_info->running_transaction->transid) {
+		WARN_ON(!btrfs_tree_locked(buf));
+		clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
+					  buf);
+	}
+	return 0;
+}
+
+static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
+			u32 stripesize, struct btrfs_root *root,
+			struct btrfs_fs_info *fs_info,
+			u64 objectid)
+{
+	root->node = NULL;
+	root->commit_root = NULL;
+	root->ref_tree = NULL;
+	root->sectorsize = sectorsize;
+	root->nodesize = nodesize;
+	root->leafsize = leafsize;
+	root->stripesize = stripesize;
+	root->ref_cows = 0;
+	root->track_dirty = 0;
+
+	root->fs_info = fs_info;
+	root->objectid = objectid;
+	root->last_trans = 0;
+	root->highest_inode = 0;
+	root->last_inode_alloc = 0;
+	root->name = NULL;
+	root->in_sysfs = 0;
+
+	INIT_LIST_HEAD(&root->dirty_list);
+	INIT_LIST_HEAD(&root->orphan_list);
+	INIT_LIST_HEAD(&root->dead_list);
+	spin_lock_init(&root->node_lock);
+	spin_lock_init(&root->list_lock);
+	mutex_init(&root->objectid_mutex);
+	mutex_init(&root->log_mutex);
+	extent_io_tree_init(&root->dirty_log_pages,
+			     fs_info->btree_inode->i_mapping, GFP_NOFS);
+
+	btrfs_leaf_ref_tree_init(&root->ref_tree_struct);
+	root->ref_tree = &root->ref_tree_struct;
+
+	memset(&root->root_key, 0, sizeof(root->root_key));
+	memset(&root->root_item, 0, sizeof(root->root_item));
+	memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
+	memset(&root->root_kobj, 0, sizeof(root->root_kobj));
+	root->defrag_trans_start = fs_info->generation;
+	init_completion(&root->kobj_unregister);
+	root->defrag_running = 0;
+	root->defrag_level = 0;
+	root->root_key.objectid = objectid;
+	root->anon_super.s_root = NULL;
+	root->anon_super.s_dev = 0;
+	INIT_LIST_HEAD(&root->anon_super.s_list);
+	INIT_LIST_HEAD(&root->anon_super.s_instances);
+	init_rwsem(&root->anon_super.s_umount);
+
+	return 0;
+}
+
+static int find_and_setup_root(struct btrfs_root *tree_root,
+			       struct btrfs_fs_info *fs_info,
+			       u64 objectid,
+			       struct btrfs_root *root)
+{
+	int ret;
+	u32 blocksize;
+	u64 generation;
+
+	__setup_root(tree_root->nodesize, tree_root->leafsize,
+		     tree_root->sectorsize, tree_root->stripesize,
+		     root, fs_info, objectid);
+	ret = btrfs_find_last_root(tree_root, objectid,
+				   &root->root_item, &root->root_key);
+	BUG_ON(ret);
+
+	generation = btrfs_root_generation(&root->root_item);
+	blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
+	root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
+				     blocksize, generation);
+	BUG_ON(!root->node);
+	return 0;
+}
+
+int btrfs_free_log_root_tree(struct btrfs_trans_handle *trans,
+			     struct btrfs_fs_info *fs_info)
+{
+	struct extent_buffer *eb;
+	struct btrfs_root *log_root_tree = fs_info->log_root_tree;
+	u64 start = 0;
+	u64 end = 0;
+	int ret;
+
+	if (!log_root_tree)
+		return 0;
+
+	while (1) {
+		ret = find_first_extent_bit(&log_root_tree->dirty_log_pages,
+				    0, &start, &end, EXTENT_DIRTY);
+		if (ret)
+			break;
+
+		clear_extent_dirty(&log_root_tree->dirty_log_pages,
+				   start, end, GFP_NOFS);
+	}
+	eb = fs_info->log_root_tree->node;
+
+	WARN_ON(btrfs_header_level(eb) != 0);
+	WARN_ON(btrfs_header_nritems(eb) != 0);
+
+	ret = btrfs_free_reserved_extent(fs_info->tree_root,
+				eb->start, eb->len);
+	BUG_ON(ret);
+
+	free_extent_buffer(eb);
+	kfree(fs_info->log_root_tree);
+	fs_info->log_root_tree = NULL;
+	return 0;
+}
+
+int btrfs_init_log_root_tree(struct btrfs_trans_handle *trans,
+			     struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_root *root;
+	struct btrfs_root *tree_root = fs_info->tree_root;
+
+	root = kzalloc(sizeof(*root), GFP_NOFS);
+	if (!root)
+		return -ENOMEM;
+
+	__setup_root(tree_root->nodesize, tree_root->leafsize,
+		     tree_root->sectorsize, tree_root->stripesize,
+		     root, fs_info, BTRFS_TREE_LOG_OBJECTID);
+
+	root->root_key.objectid = BTRFS_TREE_LOG_OBJECTID;
+	root->root_key.type = BTRFS_ROOT_ITEM_KEY;
+	root->root_key.offset = BTRFS_TREE_LOG_OBJECTID;
+	root->ref_cows = 0;
+
+	root->node = btrfs_alloc_free_block(trans, root, root->leafsize,
+					    0, BTRFS_TREE_LOG_OBJECTID,
+					    trans->transid, 0, 0, 0);
+
+	btrfs_set_header_nritems(root->node, 0);
+	btrfs_set_header_level(root->node, 0);
+	btrfs_set_header_bytenr(root->node, root->node->start);
+	btrfs_set_header_generation(root->node, trans->transid);
+	btrfs_set_header_owner(root->node, BTRFS_TREE_LOG_OBJECTID);
+
+	write_extent_buffer(root->node, root->fs_info->fsid,
+			    (unsigned long)btrfs_header_fsid(root->node),
+			    BTRFS_FSID_SIZE);
+	btrfs_mark_buffer_dirty(root->node);
+	btrfs_tree_unlock(root->node);
+	fs_info->log_root_tree = root;
+	return 0;
+}
+
+struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_root *tree_root,
+					       struct btrfs_key *location)
+{
+	struct btrfs_root *root;
+	struct btrfs_fs_info *fs_info = tree_root->fs_info;
+	struct btrfs_path *path;
+	struct extent_buffer *l;
+	u64 highest_inode;
+	u64 generation;
+	u32 blocksize;
+	int ret = 0;
+
+	root = kzalloc(sizeof(*root), GFP_NOFS);
+	if (!root)
+		return ERR_PTR(-ENOMEM);
+	if (location->offset == (u64)-1) {
+		ret = find_and_setup_root(tree_root, fs_info,
+					  location->objectid, root);
+		if (ret) {
+			kfree(root);
+			return ERR_PTR(ret);
+		}
+		goto insert;
+	}
+
+	__setup_root(tree_root->nodesize, tree_root->leafsize,
+		     tree_root->sectorsize, tree_root->stripesize,
+		     root, fs_info, location->objectid);
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+	ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
+	if (ret != 0) {
+		if (ret > 0)
+			ret = -ENOENT;
+		goto out;
+	}
+	l = path->nodes[0];
+	read_extent_buffer(l, &root->root_item,
+	       btrfs_item_ptr_offset(l, path->slots[0]),
+	       sizeof(root->root_item));
+	memcpy(&root->root_key, location, sizeof(*location));
+	ret = 0;
+out:
+	btrfs_release_path(root, path);
+	btrfs_free_path(path);
+	if (ret) {
+		kfree(root);
+		return ERR_PTR(ret);
+	}
+	generation = btrfs_root_generation(&root->root_item);
+	blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
+	root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
+				     blocksize, generation);
+	BUG_ON(!root->node);
+insert:
+	if (location->objectid != BTRFS_TREE_LOG_OBJECTID) {
+		root->ref_cows = 1;
+		ret = btrfs_find_highest_inode(root, &highest_inode);
+		if (ret == 0) {
+			root->highest_inode = highest_inode;
+			root->last_inode_alloc = highest_inode;
+		}
+	}
+	return root;
+}
+
+struct btrfs_root *btrfs_lookup_fs_root(struct btrfs_fs_info *fs_info,
+					u64 root_objectid)
+{
+	struct btrfs_root *root;
+
+	if (root_objectid == BTRFS_ROOT_TREE_OBJECTID)
+		return fs_info->tree_root;
+	if (root_objectid == BTRFS_EXTENT_TREE_OBJECTID)
+		return fs_info->extent_root;
+
+	root = radix_tree_lookup(&fs_info->fs_roots_radix,
+				 (unsigned long)root_objectid);
+	return root;
+}
+
+struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
+					      struct btrfs_key *location)
+{
+	struct btrfs_root *root;
+	int ret;
+
+	if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
+		return fs_info->tree_root;
+	if (location->objectid == BTRFS_EXTENT_TREE_OBJECTID)
+		return fs_info->extent_root;
+	if (location->objectid == BTRFS_CHUNK_TREE_OBJECTID)
+		return fs_info->chunk_root;
+	if (location->objectid == BTRFS_DEV_TREE_OBJECTID)
+		return fs_info->dev_root;
+	if (location->objectid == BTRFS_CSUM_TREE_OBJECTID)
+		return fs_info->csum_root;
+
+	root = radix_tree_lookup(&fs_info->fs_roots_radix,
+				 (unsigned long)location->objectid);
+	if (root)
+		return root;
+
+	root = btrfs_read_fs_root_no_radix(fs_info->tree_root, location);
+	if (IS_ERR(root))
+		return root;
+
+	set_anon_super(&root->anon_super, NULL);
+
+	ret = radix_tree_insert(&fs_info->fs_roots_radix,
+				(unsigned long)root->root_key.objectid,
+				root);
+	if (ret) {
+		free_extent_buffer(root->node);
+		kfree(root);
+		return ERR_PTR(ret);
+	}
+	if (!(fs_info->sb->s_flags & MS_RDONLY)) {
+		ret = btrfs_find_dead_roots(fs_info->tree_root,
+					    root->root_key.objectid, root);
+		BUG_ON(ret);
+		btrfs_orphan_cleanup(root);
+	}
+	return root;
+}
+
+struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
+				      struct btrfs_key *location,
+				      const char *name, int namelen)
+{
+	struct btrfs_root *root;
+	int ret;
+
+	root = btrfs_read_fs_root_no_name(fs_info, location);
+	if (!root)
+		return NULL;
+
+	if (root->in_sysfs)
+		return root;
+
+	ret = btrfs_set_root_name(root, name, namelen);
+	if (ret) {
+		free_extent_buffer(root->node);
+		kfree(root);
+		return ERR_PTR(ret);
+	}
+#if 0
+	ret = btrfs_sysfs_add_root(root);
+	if (ret) {
+		free_extent_buffer(root->node);
+		kfree(root->name);
+		kfree(root);
+		return ERR_PTR(ret);
+	}
+#endif
+	root->in_sysfs = 1;
+	return root;
+}
+
+static int btrfs_congested_fn(void *congested_data, int bdi_bits)
+{
+	struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;
+	int ret = 0;
+	struct list_head *cur;
+	struct btrfs_device *device;
+	struct backing_dev_info *bdi;
+#if 0
+	if ((bdi_bits & (1 << BDI_write_congested)) &&
+	    btrfs_congested_async(info, 0))
+		return 1;
+#endif
+	list_for_each(cur, &info->fs_devices->devices) {
+		device = list_entry(cur, struct btrfs_device, dev_list);
+		if (!device->bdev)
+			continue;
+		bdi = blk_get_backing_dev_info(device->bdev);
+		if (bdi && bdi_congested(bdi, bdi_bits)) {
+			ret = 1;
+			break;
+		}
+	}
+	return ret;
+}
+
+/*
+ * this unplugs every device on the box, and it is only used when page
+ * is null
+ */
+static void __unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
+{
+	struct list_head *cur;
+	struct btrfs_device *device;
+	struct btrfs_fs_info *info;
+
+	info = (struct btrfs_fs_info *)bdi->unplug_io_data;
+	list_for_each(cur, &info->fs_devices->devices) {
+		device = list_entry(cur, struct btrfs_device, dev_list);
+		if (!device->bdev)
+			continue;
+
+		bdi = blk_get_backing_dev_info(device->bdev);
+		if (bdi->unplug_io_fn)
+			bdi->unplug_io_fn(bdi, page);
+	}
+}
+
+static void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
+{
+	struct inode *inode;
+	struct extent_map_tree *em_tree;
+	struct extent_map *em;
+	struct address_space *mapping;
+	u64 offset;
+
+	/* the generic O_DIRECT read code does this */
+	if (1 || !page) {
+		__unplug_io_fn(bdi, page);
+		return;
+	}
+
+	/*
+	 * page->mapping may change at any time.  Get a consistent copy
+	 * and use that for everything below
+	 */
+	smp_mb();
+	mapping = page->mapping;
+	if (!mapping)
+		return;
+
+	inode = mapping->host;
+
+	/*
+	 * don't do the expensive searching for a small number of
+	 * devices
+	 */
+	if (BTRFS_I(inode)->root->fs_info->fs_devices->open_devices <= 2) {
+		__unplug_io_fn(bdi, page);
+		return;
+	}
+
+	offset = page_offset(page);
+
+	em_tree = &BTRFS_I(inode)->extent_tree;
+	spin_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, offset, PAGE_CACHE_SIZE);
+	spin_unlock(&em_tree->lock);
+	if (!em) {
+		__unplug_io_fn(bdi, page);
+		return;
+	}
+
+	if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
+		free_extent_map(em);
+		__unplug_io_fn(bdi, page);
+		return;
+	}
+	offset = offset - em->start;
+	btrfs_unplug_page(&BTRFS_I(inode)->root->fs_info->mapping_tree,
+			  em->block_start + offset, page);
+	free_extent_map(em);
+}
+
+static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
+{
+	bdi_init(bdi);
+	bdi->ra_pages	= default_backing_dev_info.ra_pages;
+	bdi->state		= 0;
+	bdi->capabilities	= default_backing_dev_info.capabilities;
+	bdi->unplug_io_fn	= btrfs_unplug_io_fn;
+	bdi->unplug_io_data	= info;
+	bdi->congested_fn	= btrfs_congested_fn;
+	bdi->congested_data	= info;
+	return 0;
+}
+
+static int bio_ready_for_csum(struct bio *bio)
+{
+	u64 length = 0;
+	u64 buf_len = 0;
+	u64 start = 0;
+	struct page *page;
+	struct extent_io_tree *io_tree = NULL;
+	struct btrfs_fs_info *info = NULL;
+	struct bio_vec *bvec;
+	int i;
+	int ret;
+
+	bio_for_each_segment(bvec, bio, i) {
+		page = bvec->bv_page;
+		if (page->private == EXTENT_PAGE_PRIVATE) {
+			length += bvec->bv_len;
+			continue;
+		}
+		if (!page->private) {
+			length += bvec->bv_len;
+			continue;
+		}
+		length = bvec->bv_len;
+		buf_len = page->private >> 2;
+		start = page_offset(page) + bvec->bv_offset;
+		io_tree = &BTRFS_I(page->mapping->host)->io_tree;
+		info = BTRFS_I(page->mapping->host)->root->fs_info;
+	}
+	/* are we fully contained in this bio? */
+	if (buf_len <= length)
+		return 1;
+
+	ret = extent_range_uptodate(io_tree, start + length,
+				    start + buf_len - 1);
+	if (ret == 1)
+		return ret;
+	return ret;
+}
+
+/*
+ * called by the kthread helper functions to finally call the bio end_io
+ * functions.  This is where read checksum verification actually happens
+ */
+static void end_workqueue_fn(struct btrfs_work *work)
+{
+	struct bio *bio;
+	struct end_io_wq *end_io_wq;
+	struct btrfs_fs_info *fs_info;
+	int error;
+
+	end_io_wq = container_of(work, struct end_io_wq, work);
+	bio = end_io_wq->bio;
+	fs_info = end_io_wq->info;
+
+	/* metadata bio reads are special because the whole tree block must
+	 * be checksummed at once.  This makes sure the entire block is in
+	 * ram and up to date before trying to verify things.  For
+	 * blocksize <= pagesize, it is basically a noop
+	 */
+	if (!(bio->bi_rw & (1 << BIO_RW)) && end_io_wq->metadata &&
+	    !bio_ready_for_csum(bio)) {
+		btrfs_queue_worker(&fs_info->endio_meta_workers,
+				   &end_io_wq->work);
+		return;
+	}
+	error = end_io_wq->error;
+	bio->bi_private = end_io_wq->private;
+	bio->bi_end_io = end_io_wq->end_io;
+	kfree(end_io_wq);
+	bio_endio(bio, error);
+}
+
+static int cleaner_kthread(void *arg)
+{
+	struct btrfs_root *root = arg;
+
+	do {
+		smp_mb();
+		if (root->fs_info->closing)
+			break;
+
+		vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
+		mutex_lock(&root->fs_info->cleaner_mutex);
+		btrfs_clean_old_snapshots(root);
+		mutex_unlock(&root->fs_info->cleaner_mutex);
+
+		if (freezing(current)) {
+			refrigerator();
+		} else {
+			smp_mb();
+			if (root->fs_info->closing)
+				break;
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule();
+			__set_current_state(TASK_RUNNING);
+		}
+	} while (!kthread_should_stop());
+	return 0;
+}
+
+static int transaction_kthread(void *arg)
+{
+	struct btrfs_root *root = arg;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_transaction *cur;
+	unsigned long now;
+	unsigned long delay;
+	int ret;
+
+	do {
+		smp_mb();
+		if (root->fs_info->closing)
+			break;
+
+		delay = HZ * 30;
+		vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
+		mutex_lock(&root->fs_info->transaction_kthread_mutex);
+
+		if (root->fs_info->total_ref_cache_size > 20 * 1024 * 1024) {
+			printk(KERN_INFO "btrfs: total reference cache "
+			       "size %llu\n",
+			       root->fs_info->total_ref_cache_size);
+		}
+
+		mutex_lock(&root->fs_info->trans_mutex);
+		cur = root->fs_info->running_transaction;
+		if (!cur) {
+			mutex_unlock(&root->fs_info->trans_mutex);
+			goto sleep;
+		}
+
+		now = get_seconds();
+		if (now < cur->start_time || now - cur->start_time < 30) {
+			mutex_unlock(&root->fs_info->trans_mutex);
+			delay = HZ * 5;
+			goto sleep;
+		}
+		mutex_unlock(&root->fs_info->trans_mutex);
+		trans = btrfs_start_transaction(root, 1);
+		ret = btrfs_commit_transaction(trans, root);
+sleep:
+		wake_up_process(root->fs_info->cleaner_kthread);
+		mutex_unlock(&root->fs_info->transaction_kthread_mutex);
+
+		if (freezing(current)) {
+			refrigerator();
+		} else {
+			if (root->fs_info->closing)
+				break;
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(delay);
+			__set_current_state(TASK_RUNNING);
+		}
+	} while (!kthread_should_stop());
+	return 0;
+}
+
+struct btrfs_root *open_ctree(struct super_block *sb,
+			      struct btrfs_fs_devices *fs_devices,
+			      char *options)
+{
+	u32 sectorsize;
+	u32 nodesize;
+	u32 leafsize;
+	u32 blocksize;
+	u32 stripesize;
+	u64 generation;
+	u64 features;
+	struct btrfs_key location;
+	struct buffer_head *bh;
+	struct btrfs_root *extent_root = kzalloc(sizeof(struct btrfs_root),
+						 GFP_NOFS);
+	struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),
+						 GFP_NOFS);
+	struct btrfs_root *tree_root = kzalloc(sizeof(struct btrfs_root),
+					       GFP_NOFS);
+	struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
+						GFP_NOFS);
+	struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root),
+						GFP_NOFS);
+	struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root),
+					      GFP_NOFS);
+	struct btrfs_root *log_tree_root;
+
+	int ret;
+	int err = -EINVAL;
+
+	struct btrfs_super_block *disk_super;
+
+	if (!extent_root || !tree_root || !fs_info ||
+	    !chunk_root || !dev_root || !csum_root) {
+		err = -ENOMEM;
+		goto fail;
+	}
+	INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
+	INIT_LIST_HEAD(&fs_info->trans_list);
+	INIT_LIST_HEAD(&fs_info->dead_roots);
+	INIT_LIST_HEAD(&fs_info->hashers);
+	INIT_LIST_HEAD(&fs_info->delalloc_inodes);
+	spin_lock_init(&fs_info->hash_lock);
+	spin_lock_init(&fs_info->delalloc_lock);
+	spin_lock_init(&fs_info->new_trans_lock);
+	spin_lock_init(&fs_info->ref_cache_lock);
+
+	init_completion(&fs_info->kobj_unregister);
+	fs_info->tree_root = tree_root;
+	fs_info->extent_root = extent_root;
+	fs_info->csum_root = csum_root;
+	fs_info->chunk_root = chunk_root;
+	fs_info->dev_root = dev_root;
+	fs_info->fs_devices = fs_devices;
+	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
+	INIT_LIST_HEAD(&fs_info->space_info);
+	btrfs_mapping_init(&fs_info->mapping_tree);
+	atomic_set(&fs_info->nr_async_submits, 0);
+	atomic_set(&fs_info->async_delalloc_pages, 0);
+	atomic_set(&fs_info->async_submit_draining, 0);
+	atomic_set(&fs_info->nr_async_bios, 0);
+	atomic_set(&fs_info->throttles, 0);
+	atomic_set(&fs_info->throttle_gen, 0);
+	fs_info->sb = sb;
+	fs_info->max_extent = (u64)-1;
+	fs_info->max_inline = 8192 * 1024;
+	setup_bdi(fs_info, &fs_info->bdi);
+	fs_info->btree_inode = new_inode(sb);
+	fs_info->btree_inode->i_ino = 1;
+	fs_info->btree_inode->i_nlink = 1;
+
+	fs_info->thread_pool_size = min_t(unsigned long,
+					  num_online_cpus() + 2, 8);
+
+	INIT_LIST_HEAD(&fs_info->ordered_extents);
+	spin_lock_init(&fs_info->ordered_extent_lock);
+
+	sb->s_blocksize = 4096;
+	sb->s_blocksize_bits = blksize_bits(4096);
+
+	/*
+	 * we set the i_size on the btree inode to the max possible int.
+	 * the real end of the address space is determined by all of
+	 * the devices in the system
+	 */
+	fs_info->btree_inode->i_size = OFFSET_MAX;
+	fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
+	fs_info->btree_inode->i_mapping->backing_dev_info = &fs_info->bdi;
+
+	extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
+			     fs_info->btree_inode->i_mapping,
+			     GFP_NOFS);
+	extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree,
+			     GFP_NOFS);
+
+	BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
+
+	spin_lock_init(&fs_info->block_group_cache_lock);
+	fs_info->block_group_cache_tree.rb_node = NULL;
+
+	extent_io_tree_init(&fs_info->pinned_extents,
+			     fs_info->btree_inode->i_mapping, GFP_NOFS);
+	extent_io_tree_init(&fs_info->pending_del,
+			     fs_info->btree_inode->i_mapping, GFP_NOFS);
+	extent_io_tree_init(&fs_info->extent_ins,
+			     fs_info->btree_inode->i_mapping, GFP_NOFS);
+	fs_info->do_barriers = 1;
+
+	INIT_LIST_HEAD(&fs_info->dead_reloc_roots);
+	btrfs_leaf_ref_tree_init(&fs_info->reloc_ref_tree);
+	btrfs_leaf_ref_tree_init(&fs_info->shared_ref_tree);
+
+	BTRFS_I(fs_info->btree_inode)->root = tree_root;
+	memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
+	       sizeof(struct btrfs_key));
+	insert_inode_hash(fs_info->btree_inode);
+
+	mutex_init(&fs_info->trans_mutex);
+	mutex_init(&fs_info->tree_log_mutex);
+	mutex_init(&fs_info->drop_mutex);
+	mutex_init(&fs_info->extent_ins_mutex);
+	mutex_init(&fs_info->pinned_mutex);
+	mutex_init(&fs_info->chunk_mutex);
+	mutex_init(&fs_info->transaction_kthread_mutex);
+	mutex_init(&fs_info->cleaner_mutex);
+	mutex_init(&fs_info->volume_mutex);
+	mutex_init(&fs_info->tree_reloc_mutex);
+	init_waitqueue_head(&fs_info->transaction_throttle);
+	init_waitqueue_head(&fs_info->transaction_wait);
+	init_waitqueue_head(&fs_info->async_submit_wait);
+	init_waitqueue_head(&fs_info->tree_log_wait);
+	atomic_set(&fs_info->tree_log_commit, 0);
+	atomic_set(&fs_info->tree_log_writers, 0);
+	fs_info->tree_log_transid = 0;
+
+	__setup_root(4096, 4096, 4096, 4096, tree_root,
+		     fs_info, BTRFS_ROOT_TREE_OBJECTID);
+
+
+	bh = btrfs_read_dev_super(fs_devices->latest_bdev);
+	if (!bh)
+		goto fail_iput;
+
+	memcpy(&fs_info->super_copy, bh->b_data, sizeof(fs_info->super_copy));
+	memcpy(&fs_info->super_for_commit, &fs_info->super_copy,
+	       sizeof(fs_info->super_for_commit));
+	brelse(bh);
+
+	memcpy(fs_info->fsid, fs_info->super_copy.fsid, BTRFS_FSID_SIZE);
+
+	disk_super = &fs_info->super_copy;
+	if (!btrfs_super_root(disk_super))
+		goto fail_iput;
+
+	ret = btrfs_parse_options(tree_root, options);
+	if (ret) {
+		err = ret;
+		goto fail_iput;
+	}
+
+	features = btrfs_super_incompat_flags(disk_super) &
+		~BTRFS_FEATURE_INCOMPAT_SUPP;
+	if (features) {
+		printk(KERN_ERR "BTRFS: couldn't mount because of "
+		       "unsupported optional features (%Lx).\n",
+		       features);
+		err = -EINVAL;
+		goto fail_iput;
+	}
+
+	features = btrfs_super_compat_ro_flags(disk_super) &
+		~BTRFS_FEATURE_COMPAT_RO_SUPP;
+	if (!(sb->s_flags & MS_RDONLY) && features) {
+		printk(KERN_ERR "BTRFS: couldn't mount RDWR because of "
+		       "unsupported option features (%Lx).\n",
+		       features);
+		err = -EINVAL;
+		goto fail_iput;
+	}
+
+	/*
+	 * we need to start all the end_io workers up front because the
+	 * queue work function gets called at interrupt time, and so it
+	 * cannot dynamically grow.
+	 */
+	btrfs_init_workers(&fs_info->workers, "worker",
+			   fs_info->thread_pool_size);
+
+	btrfs_init_workers(&fs_info->delalloc_workers, "delalloc",
+			   fs_info->thread_pool_size);
+
+	btrfs_init_workers(&fs_info->submit_workers, "submit",
+			   min_t(u64, fs_devices->num_devices,
+			   fs_info->thread_pool_size));
+
+	/* a higher idle thresh on the submit workers makes it much more
+	 * likely that bios will be send down in a sane order to the
+	 * devices
+	 */
+	fs_info->submit_workers.idle_thresh = 64;
+
+	fs_info->workers.idle_thresh = 16;
+	fs_info->workers.ordered = 1;
+
+	fs_info->delalloc_workers.idle_thresh = 2;
+	fs_info->delalloc_workers.ordered = 1;
+
+	btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);
+	btrfs_init_workers(&fs_info->endio_workers, "endio",
+			   fs_info->thread_pool_size);
+	btrfs_init_workers(&fs_info->endio_meta_workers, "endio-meta",
+			   fs_info->thread_pool_size);
+	btrfs_init_workers(&fs_info->endio_meta_write_workers,
+			   "endio-meta-write", fs_info->thread_pool_size);
+	btrfs_init_workers(&fs_info->endio_write_workers, "endio-write",
+			   fs_info->thread_pool_size);
+
+	/*
+	 * endios are largely parallel and should have a very
+	 * low idle thresh
+	 */
+	fs_info->endio_workers.idle_thresh = 4;
+	fs_info->endio_write_workers.idle_thresh = 64;
+	fs_info->endio_meta_write_workers.idle_thresh = 64;
+
+	btrfs_start_workers(&fs_info->workers, 1);
+	btrfs_start_workers(&fs_info->submit_workers, 1);
+	btrfs_start_workers(&fs_info->delalloc_workers, 1);
+	btrfs_start_workers(&fs_info->fixup_workers, 1);
+	btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
+	btrfs_start_workers(&fs_info->endio_meta_workers,
+			    fs_info->thread_pool_size);
+	btrfs_start_workers(&fs_info->endio_meta_write_workers,
+			    fs_info->thread_pool_size);
+	btrfs_start_workers(&fs_info->endio_write_workers,
+			    fs_info->thread_pool_size);
+
+	fs_info->bdi.ra_pages *= btrfs_super_num_devices(disk_super);
+	fs_info->bdi.ra_pages = max(fs_info->bdi.ra_pages,
+				    4 * 1024 * 1024 / PAGE_CACHE_SIZE);
+
+	nodesize = btrfs_super_nodesize(disk_super);
+	leafsize = btrfs_super_leafsize(disk_super);
+	sectorsize = btrfs_super_sectorsize(disk_super);
+	stripesize = btrfs_super_stripesize(disk_super);
+	tree_root->nodesize = nodesize;
+	tree_root->leafsize = leafsize;
+	tree_root->sectorsize = sectorsize;
+	tree_root->stripesize = stripesize;
+
+	sb->s_blocksize = sectorsize;
+	sb->s_blocksize_bits = blksize_bits(sectorsize);
+
+	if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
+		    sizeof(disk_super->magic))) {
+		printk(KERN_INFO "btrfs: valid FS not found on %s\n", sb->s_id);
+		goto fail_sb_buffer;
+	}
+
+	mutex_lock(&fs_info->chunk_mutex);
+	ret = btrfs_read_sys_array(tree_root);
+	mutex_unlock(&fs_info->chunk_mutex);
+	if (ret) {
+		printk(KERN_WARNING "btrfs: failed to read the system "
+		       "array on %s\n", sb->s_id);
+		goto fail_sys_array;
+	}
+
+	blocksize = btrfs_level_size(tree_root,
+				     btrfs_super_chunk_root_level(disk_super));
+	generation = btrfs_super_chunk_root_generation(disk_super);
+
+	__setup_root(nodesize, leafsize, sectorsize, stripesize,
+		     chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
+
+	chunk_root->node = read_tree_block(chunk_root,
+					   btrfs_super_chunk_root(disk_super),
+					   blocksize, generation);
+	BUG_ON(!chunk_root->node);
+
+	read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
+	   (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
+	   BTRFS_UUID_SIZE);
+
+	mutex_lock(&fs_info->chunk_mutex);
+	ret = btrfs_read_chunk_tree(chunk_root);
+	mutex_unlock(&fs_info->chunk_mutex);
+	if (ret) {
+		printk(KERN_WARNING "btrfs: failed to read chunk tree on %s\n",
+		       sb->s_id);
+		goto fail_chunk_root;
+	}
+
+	btrfs_close_extra_devices(fs_devices);
+
+	blocksize = btrfs_level_size(tree_root,
+				     btrfs_super_root_level(disk_super));
+	generation = btrfs_super_generation(disk_super);
+
+	tree_root->node = read_tree_block(tree_root,
+					  btrfs_super_root(disk_super),
+					  blocksize, generation);
+	if (!tree_root->node)
+		goto fail_chunk_root;
+
+
+	ret = find_and_setup_root(tree_root, fs_info,
+				  BTRFS_EXTENT_TREE_OBJECTID, extent_root);
+	if (ret)
+		goto fail_tree_root;
+	extent_root->track_dirty = 1;
+
+	ret = find_and_setup_root(tree_root, fs_info,
+				  BTRFS_DEV_TREE_OBJECTID, dev_root);
+	dev_root->track_dirty = 1;
+
+	if (ret)
+		goto fail_extent_root;
+
+	ret = find_and_setup_root(tree_root, fs_info,
+				  BTRFS_CSUM_TREE_OBJECTID, csum_root);
+	if (ret)
+		goto fail_extent_root;
+
+	csum_root->track_dirty = 1;
+
+	btrfs_read_block_groups(extent_root);
+
+	fs_info->generation = generation;
+	fs_info->last_trans_committed = generation;
+	fs_info->data_alloc_profile = (u64)-1;
+	fs_info->metadata_alloc_profile = (u64)-1;
+	fs_info->system_alloc_profile = fs_info->metadata_alloc_profile;
+	fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
+					       "btrfs-cleaner");
+	if (!fs_info->cleaner_kthread)
+		goto fail_csum_root;
+
+	fs_info->transaction_kthread = kthread_run(transaction_kthread,
+						   tree_root,
+						   "btrfs-transaction");
+	if (!fs_info->transaction_kthread)
+		goto fail_cleaner;
+
+	if (btrfs_super_log_root(disk_super) != 0) {
+		u64 bytenr = btrfs_super_log_root(disk_super);
+
+		if (fs_devices->rw_devices == 0) {
+			printk(KERN_WARNING "Btrfs log replay required "
+			       "on RO media\n");
+			err = -EIO;
+			goto fail_trans_kthread;
+		}
+		blocksize =
+		     btrfs_level_size(tree_root,
+				      btrfs_super_log_root_level(disk_super));
+
+		log_tree_root = kzalloc(sizeof(struct btrfs_root),
+						      GFP_NOFS);
+
+		__setup_root(nodesize, leafsize, sectorsize, stripesize,
+			     log_tree_root, fs_info, BTRFS_TREE_LOG_OBJECTID);
+
+		log_tree_root->node = read_tree_block(tree_root, bytenr,
+						      blocksize,
+						      generation + 1);
+		ret = btrfs_recover_log_trees(log_tree_root);
+		BUG_ON(ret);
+
+		if (sb->s_flags & MS_RDONLY) {
+			ret =  btrfs_commit_super(tree_root);
+			BUG_ON(ret);
+		}
+	}
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		ret = btrfs_cleanup_reloc_trees(tree_root);
+		BUG_ON(ret);
+	}
+
+	location.objectid = BTRFS_FS_TREE_OBJECTID;
+	location.type = BTRFS_ROOT_ITEM_KEY;
+	location.offset = (u64)-1;
+
+	fs_info->fs_root = btrfs_read_fs_root_no_name(fs_info, &location);
+	if (!fs_info->fs_root)
+		goto fail_trans_kthread;
+	return tree_root;
+
+fail_trans_kthread:
+	kthread_stop(fs_info->transaction_kthread);
+fail_cleaner:
+	kthread_stop(fs_info->cleaner_kthread);
+
+	/*
+	 * make sure we're done with the btree inode before we stop our
+	 * kthreads
+	 */
+	filemap_write_and_wait(fs_info->btree_inode->i_mapping);
+	invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
+
+fail_csum_root:
+	free_extent_buffer(csum_root->node);
+fail_extent_root:
+	free_extent_buffer(extent_root->node);
+fail_tree_root:
+	free_extent_buffer(tree_root->node);
+fail_chunk_root:
+	free_extent_buffer(chunk_root->node);
+fail_sys_array:
+	free_extent_buffer(dev_root->node);
+fail_sb_buffer:
+	btrfs_stop_workers(&fs_info->fixup_workers);
+	btrfs_stop_workers(&fs_info->delalloc_workers);
+	btrfs_stop_workers(&fs_info->workers);
+	btrfs_stop_workers(&fs_info->endio_workers);
+	btrfs_stop_workers(&fs_info->endio_meta_workers);
+	btrfs_stop_workers(&fs_info->endio_meta_write_workers);
+	btrfs_stop_workers(&fs_info->endio_write_workers);
+	btrfs_stop_workers(&fs_info->submit_workers);
+fail_iput:
+	invalidate_inode_pages2(fs_info->btree_inode->i_mapping);
+	iput(fs_info->btree_inode);
+fail:
+	btrfs_close_devices(fs_info->fs_devices);
+	btrfs_mapping_tree_free(&fs_info->mapping_tree);
+
+	kfree(extent_root);
+	kfree(tree_root);
+	bdi_destroy(&fs_info->bdi);
+	kfree(fs_info);
+	kfree(chunk_root);
+	kfree(dev_root);
+	kfree(csum_root);
+	return ERR_PTR(err);
+}
+
+static void btrfs_end_buffer_write_sync(struct buffer_head *bh, int uptodate)
+{
+	char b[BDEVNAME_SIZE];
+
+	if (uptodate) {
+		set_buffer_uptodate(bh);
+	} else {
+		if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
+			printk(KERN_WARNING "lost page write due to "
+					"I/O error on %s\n",
+				       bdevname(bh->b_bdev, b));
+		}
+		/* note, we dont' set_buffer_write_io_error because we have
+		 * our own ways of dealing with the IO errors
+		 */
+		clear_buffer_uptodate(bh);
+	}
+	unlock_buffer(bh);
+	put_bh(bh);
+}
+
+struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
+{
+	struct buffer_head *bh;
+	struct buffer_head *latest = NULL;
+	struct btrfs_super_block *super;
+	int i;
+	u64 transid = 0;
+	u64 bytenr;
+
+	/* we would like to check all the supers, but that would make
+	 * a btrfs mount succeed after a mkfs from a different FS.
+	 * So, we need to add a special mount option to scan for
+	 * later supers, using BTRFS_SUPER_MIRROR_MAX instead
+	 */
+	for (i = 0; i < 1; i++) {
+		bytenr = btrfs_sb_offset(i);
+		if (bytenr + 4096 >= i_size_read(bdev->bd_inode))
+			break;
+		bh = __bread(bdev, bytenr / 4096, 4096);
+		if (!bh)
+			continue;
+
+		super = (struct btrfs_super_block *)bh->b_data;
+		if (btrfs_super_bytenr(super) != bytenr ||
+		    strncmp((char *)(&super->magic), BTRFS_MAGIC,
+			    sizeof(super->magic))) {
+			brelse(bh);
+			continue;
+		}
+
+		if (!latest || btrfs_super_generation(super) > transid) {
+			brelse(latest);
+			latest = bh;
+			transid = btrfs_super_generation(super);
+		} else {
+			brelse(bh);
+		}
+	}
+	return latest;
+}
+
+static int write_dev_supers(struct btrfs_device *device,
+			    struct btrfs_super_block *sb,
+			    int do_barriers, int wait, int max_mirrors)
+{
+	struct buffer_head *bh;
+	int i;
+	int ret;
+	int errors = 0;
+	u32 crc;
+	u64 bytenr;
+	int last_barrier = 0;
+
+	if (max_mirrors == 0)
+		max_mirrors = BTRFS_SUPER_MIRROR_MAX;
+
+	/* make sure only the last submit_bh does a barrier */
+	if (do_barriers) {
+		for (i = 0; i < max_mirrors; i++) {
+			bytenr = btrfs_sb_offset(i);
+			if (bytenr + BTRFS_SUPER_INFO_SIZE >=
+			    device->total_bytes)
+				break;
+			last_barrier = i;
+		}
+	}
+
+	for (i = 0; i < max_mirrors; i++) {
+		bytenr = btrfs_sb_offset(i);
+		if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
+			break;
+
+		if (wait) {
+			bh = __find_get_block(device->bdev, bytenr / 4096,
+					      BTRFS_SUPER_INFO_SIZE);
+			BUG_ON(!bh);
+			brelse(bh);
+			wait_on_buffer(bh);
+			if (buffer_uptodate(bh)) {
+				brelse(bh);
+				continue;
+			}
+		} else {
+			btrfs_set_super_bytenr(sb, bytenr);
+
+			crc = ~(u32)0;
+			crc = btrfs_csum_data(NULL, (char *)sb +
+					      BTRFS_CSUM_SIZE, crc,
+					      BTRFS_SUPER_INFO_SIZE -
+					      BTRFS_CSUM_SIZE);
+			btrfs_csum_final(crc, sb->csum);
+
+			bh = __getblk(device->bdev, bytenr / 4096,
+				      BTRFS_SUPER_INFO_SIZE);
+			memcpy(bh->b_data, sb, BTRFS_SUPER_INFO_SIZE);
+
+			set_buffer_uptodate(bh);
+			get_bh(bh);
+			lock_buffer(bh);
+			bh->b_end_io = btrfs_end_buffer_write_sync;
+		}
+
+		if (i == last_barrier && do_barriers && device->barriers) {
+			ret = submit_bh(WRITE_BARRIER, bh);
+			if (ret == -EOPNOTSUPP) {
+				printk("btrfs: disabling barriers on dev %s\n",
+				       device->name);
+				set_buffer_uptodate(bh);
+				device->barriers = 0;
+				get_bh(bh);
+				lock_buffer(bh);
+				ret = submit_bh(WRITE, bh);
+			}
+		} else {
+			ret = submit_bh(WRITE, bh);
+		}
+
+		if (!ret && wait) {
+			wait_on_buffer(bh);
+			if (!buffer_uptodate(bh))
+				errors++;
+		} else if (ret) {
+			errors++;
+		}
+		if (wait)
+			brelse(bh);
+	}
+	return errors < i ? 0 : -1;
+}
+
+int write_all_supers(struct btrfs_root *root, int max_mirrors)
+{
+	struct list_head *cur;
+	struct list_head *head = &root->fs_info->fs_devices->devices;
+	struct btrfs_device *dev;
+	struct btrfs_super_block *sb;
+	struct btrfs_dev_item *dev_item;
+	int ret;
+	int do_barriers;
+	int max_errors;
+	int total_errors = 0;
+	u64 flags;
+
+	max_errors = btrfs_super_num_devices(&root->fs_info->super_copy) - 1;
+	do_barriers = !btrfs_test_opt(root, NOBARRIER);
+
+	sb = &root->fs_info->super_for_commit;
+	dev_item = &sb->dev_item;
+	list_for_each(cur, head) {
+		dev = list_entry(cur, struct btrfs_device, dev_list);
+		if (!dev->bdev) {
+			total_errors++;
+			continue;
+		}
+		if (!dev->in_fs_metadata || !dev->writeable)
+			continue;
+
+		btrfs_set_stack_device_generation(dev_item, 0);
+		btrfs_set_stack_device_type(dev_item, dev->type);
+		btrfs_set_stack_device_id(dev_item, dev->devid);
+		btrfs_set_stack_device_total_bytes(dev_item, dev->total_bytes);
+		btrfs_set_stack_device_bytes_used(dev_item, dev->bytes_used);
+		btrfs_set_stack_device_io_align(dev_item, dev->io_align);
+		btrfs_set_stack_device_io_width(dev_item, dev->io_width);
+		btrfs_set_stack_device_sector_size(dev_item, dev->sector_size);
+		memcpy(dev_item->uuid, dev->uuid, BTRFS_UUID_SIZE);
+		memcpy(dev_item->fsid, dev->fs_devices->fsid, BTRFS_UUID_SIZE);
+
+		flags = btrfs_super_flags(sb);
+		btrfs_set_super_flags(sb, flags | BTRFS_HEADER_FLAG_WRITTEN);
+
+		ret = write_dev_supers(dev, sb, do_barriers, 0, max_mirrors);
+		if (ret)
+			total_errors++;
+	}
+	if (total_errors > max_errors) {
+		printk(KERN_ERR "btrfs: %d errors while writing supers\n",
+		       total_errors);
+		BUG();
+	}
+
+	total_errors = 0;
+	list_for_each(cur, head) {
+		dev = list_entry(cur, struct btrfs_device, dev_list);
+		if (!dev->bdev)
+			continue;
+		if (!dev->in_fs_metadata || !dev->writeable)
+			continue;
+
+		ret = write_dev_supers(dev, sb, do_barriers, 1, max_mirrors);
+		if (ret)
+			total_errors++;
+	}
+	if (total_errors > max_errors) {
+		printk(KERN_ERR "btrfs: %d errors while writing supers\n",
+		       total_errors);
+		BUG();
+	}
+	return 0;
+}
+
+int write_ctree_super(struct btrfs_trans_handle *trans,
+		      struct btrfs_root *root, int max_mirrors)
+{
+	int ret;
+
+	ret = write_all_supers(root, max_mirrors);
+	return ret;
+}
+
+int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
+{
+	radix_tree_delete(&fs_info->fs_roots_radix,
+			  (unsigned long)root->root_key.objectid);
+	if (root->anon_super.s_dev) {
+		down_write(&root->anon_super.s_umount);
+		kill_anon_super(&root->anon_super);
+	}
+	if (root->node)
+		free_extent_buffer(root->node);
+	if (root->commit_root)
+		free_extent_buffer(root->commit_root);
+	kfree(root->name);
+	kfree(root);
+	return 0;
+}
+
+static int del_fs_roots(struct btrfs_fs_info *fs_info)
+{
+	int ret;
+	struct btrfs_root *gang[8];
+	int i;
+
+	while (1) {
+		ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
+					     (void **)gang, 0,
+					     ARRAY_SIZE(gang));
+		if (!ret)
+			break;
+		for (i = 0; i < ret; i++)
+			btrfs_free_fs_root(fs_info, gang[i]);
+	}
+	return 0;
+}
+
+int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info)
+{
+	u64 root_objectid = 0;
+	struct btrfs_root *gang[8];
+	int i;
+	int ret;
+
+	while (1) {
+		ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
+					     (void **)gang, root_objectid,
+					     ARRAY_SIZE(gang));
+		if (!ret)
+			break;
+		for (i = 0; i < ret; i++) {
+			root_objectid = gang[i]->root_key.objectid;
+			ret = btrfs_find_dead_roots(fs_info->tree_root,
+						    root_objectid, gang[i]);
+			BUG_ON(ret);
+			btrfs_orphan_cleanup(gang[i]);
+		}
+		root_objectid++;
+	}
+	return 0;
+}
+
+int btrfs_commit_super(struct btrfs_root *root)
+{
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	mutex_lock(&root->fs_info->cleaner_mutex);
+	btrfs_clean_old_snapshots(root);
+	mutex_unlock(&root->fs_info->cleaner_mutex);
+	trans = btrfs_start_transaction(root, 1);
+	ret = btrfs_commit_transaction(trans, root);
+	BUG_ON(ret);
+	/* run commit again to drop the original snapshot */
+	trans = btrfs_start_transaction(root, 1);
+	btrfs_commit_transaction(trans, root);
+	ret = btrfs_write_and_wait_transaction(NULL, root);
+	BUG_ON(ret);
+
+	ret = write_ctree_super(NULL, root, 0);
+	return ret;
+}
+
+int close_ctree(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	int ret;
+
+	fs_info->closing = 1;
+	smp_mb();
+
+	kthread_stop(root->fs_info->transaction_kthread);
+	kthread_stop(root->fs_info->cleaner_kthread);
+
+	if (!(fs_info->sb->s_flags & MS_RDONLY)) {
+		ret =  btrfs_commit_super(root);
+		if (ret)
+			printk(KERN_ERR "btrfs: commit super ret %d\n", ret);
+	}
+
+	if (fs_info->delalloc_bytes) {
+		printk(KERN_INFO "btrfs: at unmount delalloc count %llu\n",
+		       fs_info->delalloc_bytes);
+	}
+	if (fs_info->total_ref_cache_size) {
+		printk(KERN_INFO "btrfs: at umount reference cache size %llu\n",
+		       (unsigned long long)fs_info->total_ref_cache_size);
+	}
+
+	if (fs_info->extent_root->node)
+		free_extent_buffer(fs_info->extent_root->node);
+
+	if (fs_info->tree_root->node)
+		free_extent_buffer(fs_info->tree_root->node);
+
+	if (root->fs_info->chunk_root->node)
+		free_extent_buffer(root->fs_info->chunk_root->node);
+
+	if (root->fs_info->dev_root->node)
+		free_extent_buffer(root->fs_info->dev_root->node);
+
+	if (root->fs_info->csum_root->node)
+		free_extent_buffer(root->fs_info->csum_root->node);
+
+	btrfs_free_block_groups(root->fs_info);
+
+	del_fs_roots(fs_info);
+
+	iput(fs_info->btree_inode);
+
+	btrfs_stop_workers(&fs_info->fixup_workers);
+	btrfs_stop_workers(&fs_info->delalloc_workers);
+	btrfs_stop_workers(&fs_info->workers);
+	btrfs_stop_workers(&fs_info->endio_workers);
+	btrfs_stop_workers(&fs_info->endio_meta_workers);
+	btrfs_stop_workers(&fs_info->endio_meta_write_workers);
+	btrfs_stop_workers(&fs_info->endio_write_workers);
+	btrfs_stop_workers(&fs_info->submit_workers);
+
+#if 0
+	while (!list_empty(&fs_info->hashers)) {
+		struct btrfs_hasher *hasher;
+		hasher = list_entry(fs_info->hashers.next, struct btrfs_hasher,
+				    hashers);
+		list_del(&hasher->hashers);
+		crypto_free_hash(&fs_info->hash_tfm);
+		kfree(hasher);
+	}
+#endif
+	btrfs_close_devices(fs_info->fs_devices);
+	btrfs_mapping_tree_free(&fs_info->mapping_tree);
+
+	bdi_destroy(&fs_info->bdi);
+
+	kfree(fs_info->extent_root);
+	kfree(fs_info->tree_root);
+	kfree(fs_info->chunk_root);
+	kfree(fs_info->dev_root);
+	kfree(fs_info->csum_root);
+	return 0;
+}
+
+int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
+{
+	int ret;
+	struct inode *btree_inode = buf->first_page->mapping->host;
+
+	ret = extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree, buf);
+	if (!ret)
+		return ret;
+
+	ret = verify_parent_transid(&BTRFS_I(btree_inode)->io_tree, buf,
+				    parent_transid);
+	return !ret;
+}
+
+int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
+{
+	struct inode *btree_inode = buf->first_page->mapping->host;
+	return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree,
+					  buf);
+}
+
+void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
+{
+	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
+	u64 transid = btrfs_header_generation(buf);
+	struct inode *btree_inode = root->fs_info->btree_inode;
+
+	WARN_ON(!btrfs_tree_locked(buf));
+	if (transid != root->fs_info->generation) {
+		printk(KERN_CRIT "btrfs transid mismatch buffer %llu, "
+		       "found %llu running %llu\n",
+			(unsigned long long)buf->start,
+			(unsigned long long)transid,
+			(unsigned long long)root->fs_info->generation);
+		WARN_ON(1);
+	}
+	set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf);
+}
+
+void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
+{
+	/*
+	 * looks as though older kernels can get into trouble with
+	 * this code, they end up stuck in balance_dirty_pages forever
+	 */
+	struct extent_io_tree *tree;
+	u64 num_dirty;
+	u64 start = 0;
+	unsigned long thresh = 32 * 1024 * 1024;
+	tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
+
+	if (current_is_pdflush() || current->flags & PF_MEMALLOC)
+		return;
+
+	num_dirty = count_range_bits(tree, &start, (u64)-1,
+				     thresh, EXTENT_DIRTY);
+	if (num_dirty > thresh) {
+		balance_dirty_pages_ratelimited_nr(
+				   root->fs_info->btree_inode->i_mapping, 1);
+	}
+	return;
+}
+
+int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
+{
+	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
+	int ret;
+	ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
+	if (ret == 0)
+		buf->flags |= EXTENT_UPTODATE;
+	return ret;
+}
+
+int btree_lock_page_hook(struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_buffer *eb;
+	unsigned long len;
+	u64 bytenr = page_offset(page);
+
+	if (page->private == EXTENT_PAGE_PRIVATE)
+		goto out;
+
+	len = page->private >> 2;
+	eb = find_extent_buffer(io_tree, bytenr, len, GFP_NOFS);
+	if (!eb)
+		goto out;
+
+	btrfs_tree_lock(eb);
+	spin_lock(&root->fs_info->hash_lock);
+	btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
+	spin_unlock(&root->fs_info->hash_lock);
+	btrfs_tree_unlock(eb);
+	free_extent_buffer(eb);
+out:
+	lock_page(page);
+	return 0;
+}
+
+static struct extent_io_ops btree_extent_io_ops = {
+	.write_cache_pages_lock_hook = btree_lock_page_hook,
+	.readpage_end_io_hook = btree_readpage_end_io_hook,
+	.submit_bio_hook = btree_submit_bio_hook,
+	/* note we're sharing with inode.c for the merge bio hook */
+	.merge_bio_hook = btrfs_merge_bio_hook,
+};