Merge branch 'linus' into x86/setup-lzma

Conflicts:
	init/do_mounts_rd.c

1 files changed, 1097 insertions, 0 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
new file mode 100644
index 00000000000..8a08f944334
--- /dev/null
+++ b/fs/btrfs/transaction.c
@@ -0,0 +1,1097 @@
+/*
+ * 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/fs.h>
+#include <linux/sched.h>
+#include <linux/writeback.h>
+#include <linux/pagemap.h>
+#include <linux/blkdev.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "locking.h"
+#include "ref-cache.h"
+#include "tree-log.h"
+
+#define BTRFS_ROOT_TRANS_TAG 0
+
+static noinline void put_transaction(struct btrfs_transaction *transaction)
+{
+	WARN_ON(transaction->use_count == 0);
+	transaction->use_count--;
+	if (transaction->use_count == 0) {
+		list_del_init(&transaction->list);
+		memset(transaction, 0, sizeof(*transaction));
+		kmem_cache_free(btrfs_transaction_cachep, transaction);
+	}
+}
+
+/*
+ * either allocate a new transaction or hop into the existing one
+ */
+static noinline int join_transaction(struct btrfs_root *root)
+{
+	struct btrfs_transaction *cur_trans;
+	cur_trans = root->fs_info->running_transaction;
+	if (!cur_trans) {
+		cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
+					     GFP_NOFS);
+		BUG_ON(!cur_trans);
+		root->fs_info->generation++;
+		root->fs_info->last_alloc = 0;
+		root->fs_info->last_data_alloc = 0;
+		cur_trans->num_writers = 1;
+		cur_trans->num_joined = 0;
+		cur_trans->transid = root->fs_info->generation;
+		init_waitqueue_head(&cur_trans->writer_wait);
+		init_waitqueue_head(&cur_trans->commit_wait);
+		cur_trans->in_commit = 0;
+		cur_trans->blocked = 0;
+		cur_trans->use_count = 1;
+		cur_trans->commit_done = 0;
+		cur_trans->start_time = get_seconds();
+		INIT_LIST_HEAD(&cur_trans->pending_snapshots);
+		list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
+		extent_io_tree_init(&cur_trans->dirty_pages,
+				     root->fs_info->btree_inode->i_mapping,
+				     GFP_NOFS);
+		spin_lock(&root->fs_info->new_trans_lock);
+		root->fs_info->running_transaction = cur_trans;
+		spin_unlock(&root->fs_info->new_trans_lock);
+	} else {
+		cur_trans->num_writers++;
+		cur_trans->num_joined++;
+	}
+
+	return 0;
+}
+
+/*
+ * this does all the record keeping required to make sure that a reference
+ * counted root is properly recorded in a given transaction.  This is required
+ * to make sure the old root from before we joined the transaction is deleted
+ * when the transaction commits
+ */
+noinline int btrfs_record_root_in_trans(struct btrfs_root *root)
+{
+	struct btrfs_dirty_root *dirty;
+	u64 running_trans_id = root->fs_info->running_transaction->transid;
+	if (root->ref_cows && root->last_trans < running_trans_id) {
+		WARN_ON(root == root->fs_info->extent_root);
+		if (root->root_item.refs != 0) {
+			radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+				   (unsigned long)root->root_key.objectid,
+				   BTRFS_ROOT_TRANS_TAG);
+
+			dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+			BUG_ON(!dirty);
+			dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
+			BUG_ON(!dirty->root);
+			dirty->latest_root = root;
+			INIT_LIST_HEAD(&dirty->list);
+
+			root->commit_root = btrfs_root_node(root);
+
+			memcpy(dirty->root, root, sizeof(*root));
+			spin_lock_init(&dirty->root->node_lock);
+			spin_lock_init(&dirty->root->list_lock);
+			mutex_init(&dirty->root->objectid_mutex);
+			mutex_init(&dirty->root->log_mutex);
+			INIT_LIST_HEAD(&dirty->root->dead_list);
+			dirty->root->node = root->commit_root;
+			dirty->root->commit_root = NULL;
+
+			spin_lock(&root->list_lock);
+			list_add(&dirty->root->dead_list, &root->dead_list);
+			spin_unlock(&root->list_lock);
+
+			root->dirty_root = dirty;
+		} else {
+			WARN_ON(1);
+		}
+		root->last_trans = running_trans_id;
+	}
+	return 0;
+}
+
+/* wait for commit against the current transaction to become unblocked
+ * when this is done, it is safe to start a new transaction, but the current
+ * transaction might not be fully on disk.
+ */
+static void wait_current_trans(struct btrfs_root *root)
+{
+	struct btrfs_transaction *cur_trans;
+
+	cur_trans = root->fs_info->running_transaction;
+	if (cur_trans && cur_trans->blocked) {
+		DEFINE_WAIT(wait);
+		cur_trans->use_count++;
+		while (1) {
+			prepare_to_wait(&root->fs_info->transaction_wait, &wait,
+					TASK_UNINTERRUPTIBLE);
+			if (cur_trans->blocked) {
+				mutex_unlock(&root->fs_info->trans_mutex);
+				schedule();
+				mutex_lock(&root->fs_info->trans_mutex);
+				finish_wait(&root->fs_info->transaction_wait,
+					    &wait);
+			} else {
+				finish_wait(&root->fs_info->transaction_wait,
+					    &wait);
+				break;
+			}
+		}
+		put_transaction(cur_trans);
+	}
+}
+
+static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
+					     int num_blocks, int wait)
+{
+	struct btrfs_trans_handle *h =
+		kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
+	int ret;
+
+	mutex_lock(&root->fs_info->trans_mutex);
+	if (!root->fs_info->log_root_recovering &&
+	    ((wait == 1 && !root->fs_info->open_ioctl_trans) || wait == 2))
+		wait_current_trans(root);
+	ret = join_transaction(root);
+	BUG_ON(ret);
+
+	btrfs_record_root_in_trans(root);
+	h->transid = root->fs_info->running_transaction->transid;
+	h->transaction = root->fs_info->running_transaction;
+	h->blocks_reserved = num_blocks;
+	h->blocks_used = 0;
+	h->block_group = 0;
+	h->alloc_exclude_nr = 0;
+	h->alloc_exclude_start = 0;
+	root->fs_info->running_transaction->use_count++;
+	mutex_unlock(&root->fs_info->trans_mutex);
+	return h;
+}
+
+struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
+						   int num_blocks)
+{
+	return start_transaction(root, num_blocks, 1);
+}
+struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
+						   int num_blocks)
+{
+	return start_transaction(root, num_blocks, 0);
+}
+
+struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
+							 int num_blocks)
+{
+	return start_transaction(r, num_blocks, 2);
+}
+
+/* wait for a transaction commit to be fully complete */
+static noinline int wait_for_commit(struct btrfs_root *root,
+				    struct btrfs_transaction *commit)
+{
+	DEFINE_WAIT(wait);
+	mutex_lock(&root->fs_info->trans_mutex);
+	while (!commit->commit_done) {
+		prepare_to_wait(&commit->commit_wait, &wait,
+				TASK_UNINTERRUPTIBLE);
+		if (commit->commit_done)
+			break;
+		mutex_unlock(&root->fs_info->trans_mutex);
+		schedule();
+		mutex_lock(&root->fs_info->trans_mutex);
+	}
+	mutex_unlock(&root->fs_info->trans_mutex);
+	finish_wait(&commit->commit_wait, &wait);
+	return 0;
+}
+
+/*
+ * rate limit against the drop_snapshot code.  This helps to slow down new
+ * operations if the drop_snapshot code isn't able to keep up.
+ */
+static void throttle_on_drops(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *info = root->fs_info;
+	int harder_count = 0;
+
+harder:
+	if (atomic_read(&info->throttles)) {
+		DEFINE_WAIT(wait);
+		int thr;
+		thr = atomic_read(&info->throttle_gen);
+
+		do {
+			prepare_to_wait(&info->transaction_throttle,
+					&wait, TASK_UNINTERRUPTIBLE);
+			if (!atomic_read(&info->throttles)) {
+				finish_wait(&info->transaction_throttle, &wait);
+				break;
+			}
+			schedule();
+			finish_wait(&info->transaction_throttle, &wait);
+		} while (thr == atomic_read(&info->throttle_gen));
+		harder_count++;
+
+		if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
+		    harder_count < 2)
+			goto harder;
+
+		if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
+		    harder_count < 10)
+			goto harder;
+
+		if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
+		    harder_count < 20)
+			goto harder;
+	}
+}
+
+void btrfs_throttle(struct btrfs_root *root)
+{
+	mutex_lock(&root->fs_info->trans_mutex);
+	if (!root->fs_info->open_ioctl_trans)
+		wait_current_trans(root);
+	mutex_unlock(&root->fs_info->trans_mutex);
+
+	throttle_on_drops(root);
+}
+
+static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root, int throttle)
+{
+	struct btrfs_transaction *cur_trans;
+	struct btrfs_fs_info *info = root->fs_info;
+
+	mutex_lock(&info->trans_mutex);
+	cur_trans = info->running_transaction;
+	WARN_ON(cur_trans != trans->transaction);
+	WARN_ON(cur_trans->num_writers < 1);
+	cur_trans->num_writers--;
+
+	if (waitqueue_active(&cur_trans->writer_wait))
+		wake_up(&cur_trans->writer_wait);
+	put_transaction(cur_trans);
+	mutex_unlock(&info->trans_mutex);
+	memset(trans, 0, sizeof(*trans));
+	kmem_cache_free(btrfs_trans_handle_cachep, trans);
+
+	if (throttle)
+		throttle_on_drops(root);
+
+	return 0;
+}
+
+int btrfs_end_transaction(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root)
+{
+	return __btrfs_end_transaction(trans, root, 0);
+}
+
+int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
+				   struct btrfs_root *root)
+{
+	return __btrfs_end_transaction(trans, root, 1);
+}
+
+/*
+ * when btree blocks are allocated, they have some corresponding bits set for
+ * them in one of two extent_io trees.  This is used to make sure all of
+ * those extents are on disk for transaction or log commit
+ */
+int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
+					struct extent_io_tree *dirty_pages)
+{
+	int ret;
+	int err = 0;
+	int werr = 0;
+	struct page *page;
+	struct inode *btree_inode = root->fs_info->btree_inode;
+	u64 start = 0;
+	u64 end;
+	unsigned long index;
+
+	while (1) {
+		ret = find_first_extent_bit(dirty_pages, start, &start, &end,
+					    EXTENT_DIRTY);
+		if (ret)
+			break;
+		while (start <= end) {
+			cond_resched();
+
+			index = start >> PAGE_CACHE_SHIFT;
+			start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
+			page = find_get_page(btree_inode->i_mapping, index);
+			if (!page)
+				continue;
+
+			btree_lock_page_hook(page);
+			if (!page->mapping) {
+				unlock_page(page);
+				page_cache_release(page);
+				continue;
+			}
+
+			if (PageWriteback(page)) {
+				if (PageDirty(page))
+					wait_on_page_writeback(page);
+				else {
+					unlock_page(page);
+					page_cache_release(page);
+					continue;
+				}
+			}
+			err = write_one_page(page, 0);
+			if (err)
+				werr = err;
+			page_cache_release(page);
+		}
+	}
+	while (1) {
+		ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
+					    EXTENT_DIRTY);
+		if (ret)
+			break;
+
+		clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
+		while (start <= end) {
+			index = start >> PAGE_CACHE_SHIFT;
+			start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
+			page = find_get_page(btree_inode->i_mapping, index);
+			if (!page)
+				continue;
+			if (PageDirty(page)) {
+				btree_lock_page_hook(page);
+				wait_on_page_writeback(page);
+				err = write_one_page(page, 0);
+				if (err)
+					werr = err;
+			}
+			wait_on_page_writeback(page);
+			page_cache_release(page);
+			cond_resched();
+		}
+	}
+	if (err)
+		werr = err;
+	return werr;
+}
+
+int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
+				     struct btrfs_root *root)
+{
+	if (!trans || !trans->transaction) {
+		struct inode *btree_inode;
+		btree_inode = root->fs_info->btree_inode;
+		return filemap_write_and_wait(btree_inode->i_mapping);
+	}
+	return btrfs_write_and_wait_marked_extents(root,
+					   &trans->transaction->dirty_pages);
+}
+
+/*
+ * this is used to update the root pointer in the tree of tree roots.
+ *
+ * But, in the case of the extent allocation tree, updating the root
+ * pointer may allocate blocks which may change the root of the extent
+ * allocation tree.
+ *
+ * So, this loops and repeats and makes sure the cowonly root didn't
+ * change while the root pointer was being updated in the metadata.
+ */
+static int update_cowonly_root(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *root)
+{
+	int ret;
+	u64 old_root_bytenr;
+	struct btrfs_root *tree_root = root->fs_info->tree_root;
+
+	btrfs_extent_post_op(trans, root);
+	btrfs_write_dirty_block_groups(trans, root);
+	btrfs_extent_post_op(trans, root);
+
+	while (1) {
+		old_root_bytenr = btrfs_root_bytenr(&root->root_item);
+		if (old_root_bytenr == root->node->start)
+			break;
+		btrfs_set_root_bytenr(&root->root_item,
+				       root->node->start);
+		btrfs_set_root_level(&root->root_item,
+				     btrfs_header_level(root->node));
+		btrfs_set_root_generation(&root->root_item, trans->transid);
+
+		btrfs_extent_post_op(trans, root);
+
+		ret = btrfs_update_root(trans, tree_root,
+					&root->root_key,
+					&root->root_item);
+		BUG_ON(ret);
+		btrfs_write_dirty_block_groups(trans, root);
+		btrfs_extent_post_op(trans, root);
+	}
+	return 0;
+}
+
+/*
+ * update all the cowonly tree roots on disk
+ */
+int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct list_head *next;
+	struct extent_buffer *eb;
+
+	btrfs_extent_post_op(trans, fs_info->tree_root);
+
+	eb = btrfs_lock_root_node(fs_info->tree_root);
+	btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, 0);
+	btrfs_tree_unlock(eb);
+	free_extent_buffer(eb);
+
+	btrfs_extent_post_op(trans, fs_info->tree_root);
+
+	while (!list_empty(&fs_info->dirty_cowonly_roots)) {
+		next = fs_info->dirty_cowonly_roots.next;
+		list_del_init(next);
+		root = list_entry(next, struct btrfs_root, dirty_list);
+
+		update_cowonly_root(trans, root);
+	}
+	return 0;
+}
+
+/*
+ * dead roots are old snapshots that need to be deleted.  This allocates
+ * a dirty root struct and adds it into the list of dead roots that need to
+ * be deleted
+ */
+int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest)
+{
+	struct btrfs_dirty_root *dirty;
+
+	dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+	if (!dirty)
+		return -ENOMEM;
+	dirty->root = root;
+	dirty->latest_root = latest;
+
+	mutex_lock(&root->fs_info->trans_mutex);
+	list_add(&dirty->list, &latest->fs_info->dead_roots);
+	mutex_unlock(&root->fs_info->trans_mutex);
+	return 0;
+}
+
+/*
+ * at transaction commit time we need to schedule the old roots for
+ * deletion via btrfs_drop_snapshot.  This runs through all the
+ * reference counted roots that were modified in the current
+ * transaction and puts them into the drop list
+ */
+static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
+				    struct radix_tree_root *radix,
+				    struct list_head *list)
+{
+	struct btrfs_dirty_root *dirty;
+	struct btrfs_root *gang[8];
+	struct btrfs_root *root;
+	int i;
+	int ret;
+	int err = 0;
+	u32 refs;
+
+	while (1) {
+		ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
+						 ARRAY_SIZE(gang),
+						 BTRFS_ROOT_TRANS_TAG);
+		if (ret == 0)
+			break;
+		for (i = 0; i < ret; i++) {
+			root = gang[i];
+			radix_tree_tag_clear(radix,
+				     (unsigned long)root->root_key.objectid,
+				     BTRFS_ROOT_TRANS_TAG);
+
+			BUG_ON(!root->ref_tree);
+			dirty = root->dirty_root;
+
+			btrfs_free_log(trans, root);
+			btrfs_free_reloc_root(trans, root);
+
+			if (root->commit_root == root->node) {
+				WARN_ON(root->node->start !=
+					btrfs_root_bytenr(&root->root_item));
+
+				free_extent_buffer(root->commit_root);
+				root->commit_root = NULL;
+				root->dirty_root = NULL;
+
+				spin_lock(&root->list_lock);
+				list_del_init(&dirty->root->dead_list);
+				spin_unlock(&root->list_lock);
+
+				kfree(dirty->root);
+				kfree(dirty);
+
+				/* make sure to update the root on disk
+				 * so we get any updates to the block used
+				 * counts
+				 */
+				err = btrfs_update_root(trans,
+						root->fs_info->tree_root,
+						&root->root_key,
+						&root->root_item);
+				continue;
+			}
+
+			memset(&root->root_item.drop_progress, 0,
+			       sizeof(struct btrfs_disk_key));
+			root->root_item.drop_level = 0;
+			root->commit_root = NULL;
+			root->dirty_root = NULL;
+			root->root_key.offset = root->fs_info->generation;
+			btrfs_set_root_bytenr(&root->root_item,
+					      root->node->start);
+			btrfs_set_root_level(&root->root_item,
+					     btrfs_header_level(root->node));
+			btrfs_set_root_generation(&root->root_item,
+						  root->root_key.offset);
+
+			err = btrfs_insert_root(trans, root->fs_info->tree_root,
+						&root->root_key,
+						&root->root_item);
+			if (err)
+				break;
+
+			refs = btrfs_root_refs(&dirty->root->root_item);
+			btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
+			err = btrfs_update_root(trans, root->fs_info->tree_root,
+						&dirty->root->root_key,
+						&dirty->root->root_item);
+
+			BUG_ON(err);
+			if (refs == 1) {
+				list_add(&dirty->list, list);
+			} else {
+				WARN_ON(1);
+				free_extent_buffer(dirty->root->node);
+				kfree(dirty->root);
+				kfree(dirty);
+			}
+		}
+	}
+	return err;
+}
+
+/*
+ * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
+ * otherwise every leaf in the btree is read and defragged.
+ */
+int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
+{
+	struct btrfs_fs_info *info = root->fs_info;
+	int ret;
+	struct btrfs_trans_handle *trans;
+	unsigned long nr;
+
+	smp_mb();
+	if (root->defrag_running)
+		return 0;
+	trans = btrfs_start_transaction(root, 1);
+	while (1) {
+		root->defrag_running = 1;
+		ret = btrfs_defrag_leaves(trans, root, cacheonly);
+		nr = trans->blocks_used;
+		btrfs_end_transaction(trans, root);
+		btrfs_btree_balance_dirty(info->tree_root, nr);
+		cond_resched();
+
+		trans = btrfs_start_transaction(root, 1);
+		if (root->fs_info->closing || ret != -EAGAIN)
+			break;
+	}
+	root->defrag_running = 0;
+	smp_mb();
+	btrfs_end_transaction(trans, root);
+	return 0;
+}
+
+/*
+ * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
+ * all of them
+ */
+static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
+				     struct list_head *list)
+{
+	struct btrfs_dirty_root *dirty;
+	struct btrfs_trans_handle *trans;
+	unsigned long nr;
+	u64 num_bytes;
+	u64 bytes_used;
+	u64 max_useless;
+	int ret = 0;
+	int err;
+
+	while (!list_empty(list)) {
+		struct btrfs_root *root;
+
+		dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
+		list_del_init(&dirty->list);
+
+		num_bytes = btrfs_root_used(&dirty->root->root_item);
+		root = dirty->latest_root;
+		atomic_inc(&root->fs_info->throttles);
+
+		while (1) {
+			trans = btrfs_start_transaction(tree_root, 1);
+			mutex_lock(&root->fs_info->drop_mutex);
+			ret = btrfs_drop_snapshot(trans, dirty->root);
+			if (ret != -EAGAIN)
+				break;
+			mutex_unlock(&root->fs_info->drop_mutex);
+
+			err = btrfs_update_root(trans,
+					tree_root,
+					&dirty->root->root_key,
+					&dirty->root->root_item);
+			if (err)
+				ret = err;
+			nr = trans->blocks_used;
+			ret = btrfs_end_transaction(trans, tree_root);
+			BUG_ON(ret);
+
+			btrfs_btree_balance_dirty(tree_root, nr);
+			cond_resched();
+		}
+		BUG_ON(ret);
+		atomic_dec(&root->fs_info->throttles);
+		wake_up(&root->fs_info->transaction_throttle);
+
+		num_bytes -= btrfs_root_used(&dirty->root->root_item);
+		bytes_used = btrfs_root_used(&root->root_item);
+		if (num_bytes) {
+			btrfs_record_root_in_trans(root);
+			btrfs_set_root_used(&root->root_item,
+					    bytes_used - num_bytes);
+		}
+
+		ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
+		if (ret) {
+			BUG();
+			break;
+		}
+		mutex_unlock(&root->fs_info->drop_mutex);
+
+		spin_lock(&root->list_lock);
+		list_del_init(&dirty->root->dead_list);
+		if (!list_empty(&root->dead_list)) {
+			struct btrfs_root *oldest;
+			oldest = list_entry(root->dead_list.prev,
+					    struct btrfs_root, dead_list);
+			max_useless = oldest->root_key.offset - 1;
+		} else {
+			max_useless = root->root_key.offset - 1;
+		}
+		spin_unlock(&root->list_lock);
+
+		nr = trans->blocks_used;
+		ret = btrfs_end_transaction(trans, tree_root);
+		BUG_ON(ret);
+
+		ret = btrfs_remove_leaf_refs(root, max_useless, 0);
+		BUG_ON(ret);
+
+		free_extent_buffer(dirty->root->node);
+		kfree(dirty->root);
+		kfree(dirty);
+
+		btrfs_btree_balance_dirty(tree_root, nr);
+		cond_resched();
+	}
+	return ret;
+}
+
+/*
+ * new snapshots need to be created at a very specific time in the
+ * transaction commit.  This does the actual creation
+ */
+static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
+				   struct btrfs_fs_info *fs_info,
+				   struct btrfs_pending_snapshot *pending)
+{
+	struct btrfs_key key;
+	struct btrfs_root_item *new_root_item;
+	struct btrfs_root *tree_root = fs_info->tree_root;
+	struct btrfs_root *root = pending->root;
+	struct extent_buffer *tmp;
+	struct extent_buffer *old;
+	int ret;
+	u64 objectid;
+
+	new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
+	if (!new_root_item) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+	ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
+	if (ret)
+		goto fail;
+
+	btrfs_record_root_in_trans(root);
+	btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
+	memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
+
+	key.objectid = objectid;
+	key.offset = trans->transid;
+	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+
+	old = btrfs_lock_root_node(root);
+	btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
+
+	btrfs_copy_root(trans, root, old, &tmp, objectid);
+	btrfs_tree_unlock(old);
+	free_extent_buffer(old);
+
+	btrfs_set_root_bytenr(new_root_item, tmp->start);
+	btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
+	btrfs_set_root_generation(new_root_item, trans->transid);
+	ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
+				new_root_item);
+	btrfs_tree_unlock(tmp);
+	free_extent_buffer(tmp);
+	if (ret)
+		goto fail;
+
+	key.offset = (u64)-1;
+	memcpy(&pending->root_key, &key, sizeof(key));
+fail:
+	kfree(new_root_item);
+	return ret;
+}
+
+static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info,
+				   struct btrfs_pending_snapshot *pending)
+{
+	int ret;
+	int namelen;
+	u64 index = 0;
+	struct btrfs_trans_handle *trans;
+	struct inode *parent_inode;
+	struct inode *inode;
+	struct btrfs_root *parent_root;
+
+	parent_inode = pending->dentry->d_parent->d_inode;
+	parent_root = BTRFS_I(parent_inode)->root;
+	trans = btrfs_join_transaction(parent_root, 1);
+
+	/*
+	 * insert the directory item
+	 */
+	namelen = strlen(pending->name);
+	ret = btrfs_set_inode_index(parent_inode, &index);
+	ret = btrfs_insert_dir_item(trans, parent_root,
+			    pending->name, namelen,
+			    parent_inode->i_ino,
+			    &pending->root_key, BTRFS_FT_DIR, index);
+
+	if (ret)
+		goto fail;
+
+	btrfs_i_size_write(parent_inode, parent_inode->i_size + namelen * 2);
+	ret = btrfs_update_inode(trans, parent_root, parent_inode);
+	BUG_ON(ret);
+
+	/* add the backref first */
+	ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
+				 pending->root_key.objectid,
+				 BTRFS_ROOT_BACKREF_KEY,
+				 parent_root->root_key.objectid,
+				 parent_inode->i_ino, index, pending->name,
+				 namelen);
+
+	BUG_ON(ret);
+
+	/* now add the forward ref */
+	ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
+				 parent_root->root_key.objectid,
+				 BTRFS_ROOT_REF_KEY,
+				 pending->root_key.objectid,
+				 parent_inode->i_ino, index, pending->name,
+				 namelen);
+
+	inode = btrfs_lookup_dentry(parent_inode, pending->dentry);
+	d_instantiate(pending->dentry, inode);
+fail:
+	btrfs_end_transaction(trans, fs_info->fs_root);
+	return ret;
+}
+
+/*
+ * create all the snapshots we've scheduled for creation
+ */
+static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
+					     struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_pending_snapshot *pending;
+	struct list_head *head = &trans->transaction->pending_snapshots;
+	struct list_head *cur;
+	int ret;
+
+	list_for_each(cur, head) {
+		pending = list_entry(cur, struct btrfs_pending_snapshot, list);
+		ret = create_pending_snapshot(trans, fs_info, pending);
+		BUG_ON(ret);
+	}
+	return 0;
+}
+
+static noinline int finish_pending_snapshots(struct btrfs_trans_handle *trans,
+					     struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_pending_snapshot *pending;
+	struct list_head *head = &trans->transaction->pending_snapshots;
+	int ret;
+
+	while (!list_empty(head)) {
+		pending = list_entry(head->next,
+				     struct btrfs_pending_snapshot, list);
+		ret = finish_pending_snapshot(fs_info, pending);
+		BUG_ON(ret);
+		list_del(&pending->list);
+		kfree(pending->name);
+		kfree(pending);
+	}
+	return 0;
+}
+
+int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root)
+{
+	unsigned long joined = 0;
+	unsigned long timeout = 1;
+	struct btrfs_transaction *cur_trans;
+	struct btrfs_transaction *prev_trans = NULL;
+	struct btrfs_root *chunk_root = root->fs_info->chunk_root;
+	struct list_head dirty_fs_roots;
+	struct extent_io_tree *pinned_copy;
+	DEFINE_WAIT(wait);
+	int ret;
+
+	INIT_LIST_HEAD(&dirty_fs_roots);
+	mutex_lock(&root->fs_info->trans_mutex);
+	if (trans->transaction->in_commit) {
+		cur_trans = trans->transaction;
+		trans->transaction->use_count++;
+		mutex_unlock(&root->fs_info->trans_mutex);
+		btrfs_end_transaction(trans, root);
+
+		ret = wait_for_commit(root, cur_trans);
+		BUG_ON(ret);
+
+		mutex_lock(&root->fs_info->trans_mutex);
+		put_transaction(cur_trans);
+		mutex_unlock(&root->fs_info->trans_mutex);
+
+		return 0;
+	}
+
+	pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
+	if (!pinned_copy)
+		return -ENOMEM;
+
+	extent_io_tree_init(pinned_copy,
+			     root->fs_info->btree_inode->i_mapping, GFP_NOFS);
+
+	trans->transaction->in_commit = 1;
+	trans->transaction->blocked = 1;
+	cur_trans = trans->transaction;
+	if (cur_trans->list.prev != &root->fs_info->trans_list) {
+		prev_trans = list_entry(cur_trans->list.prev,
+					struct btrfs_transaction, list);
+		if (!prev_trans->commit_done) {
+			prev_trans->use_count++;
+			mutex_unlock(&root->fs_info->trans_mutex);
+
+			wait_for_commit(root, prev_trans);
+
+			mutex_lock(&root->fs_info->trans_mutex);
+			put_transaction(prev_trans);
+		}
+	}
+
+	do {
+		int snap_pending = 0;
+		joined = cur_trans->num_joined;
+		if (!list_empty(&trans->transaction->pending_snapshots))
+			snap_pending = 1;
+
+		WARN_ON(cur_trans != trans->transaction);
+		prepare_to_wait(&cur_trans->writer_wait, &wait,
+				TASK_UNINTERRUPTIBLE);
+
+		if (cur_trans->num_writers > 1)
+			timeout = MAX_SCHEDULE_TIMEOUT;
+		else
+			timeout = 1;
+
+		mutex_unlock(&root->fs_info->trans_mutex);
+
+		if (snap_pending) {
+			ret = btrfs_wait_ordered_extents(root, 1);
+			BUG_ON(ret);
+		}
+
+		schedule_timeout(timeout);
+
+		mutex_lock(&root->fs_info->trans_mutex);
+		finish_wait(&cur_trans->writer_wait, &wait);
+	} while (cur_trans->num_writers > 1 ||
+		 (cur_trans->num_joined != joined));
+
+	ret = create_pending_snapshots(trans, root->fs_info);
+	BUG_ON(ret);
+
+	WARN_ON(cur_trans != trans->transaction);
+
+	/* btrfs_commit_tree_roots is responsible for getting the
+	 * various roots consistent with each other.  Every pointer
+	 * in the tree of tree roots has to point to the most up to date
+	 * root for every subvolume and other tree.  So, we have to keep
+	 * the tree logging code from jumping in and changing any
+	 * of the trees.
+	 *
+	 * At this point in the commit, there can't be any tree-log
+	 * writers, but a little lower down we drop the trans mutex
+	 * and let new people in.  By holding the tree_log_mutex
+	 * from now until after the super is written, we avoid races
+	 * with the tree-log code.
+	 */
+	mutex_lock(&root->fs_info->tree_log_mutex);
+	/*
+	 * keep tree reloc code from adding new reloc trees
+	 */
+	mutex_lock(&root->fs_info->tree_reloc_mutex);
+
+
+	ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
+			      &dirty_fs_roots);
+	BUG_ON(ret);
+
+	/* add_dirty_roots gets rid of all the tree log roots, it is now
+	 * safe to free the root of tree log roots
+	 */
+	btrfs_free_log_root_tree(trans, root->fs_info);
+
+	ret = btrfs_commit_tree_roots(trans, root);
+	BUG_ON(ret);
+
+	cur_trans = root->fs_info->running_transaction;
+	spin_lock(&root->fs_info->new_trans_lock);
+	root->fs_info->running_transaction = NULL;
+	spin_unlock(&root->fs_info->new_trans_lock);
+	btrfs_set_super_generation(&root->fs_info->super_copy,
+				   cur_trans->transid);
+	btrfs_set_super_root(&root->fs_info->super_copy,
+			     root->fs_info->tree_root->node->start);
+	btrfs_set_super_root_level(&root->fs_info->super_copy,
+			   btrfs_header_level(root->fs_info->tree_root->node));
+
+	btrfs_set_super_chunk_root(&root->fs_info->super_copy,
+				   chunk_root->node->start);
+	btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
+					 btrfs_header_level(chunk_root->node));
+	btrfs_set_super_chunk_root_generation(&root->fs_info->super_copy,
+				btrfs_header_generation(chunk_root->node));
+
+	if (!root->fs_info->log_root_recovering) {
+		btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
+		btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
+	}
+
+	memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
+	       sizeof(root->fs_info->super_copy));
+
+	btrfs_copy_pinned(root, pinned_copy);
+
+	trans->transaction->blocked = 0;
+	wake_up(&root->fs_info->transaction_throttle);
+	wake_up(&root->fs_info->transaction_wait);
+
+	mutex_unlock(&root->fs_info->trans_mutex);
+	ret = btrfs_write_and_wait_transaction(trans, root);
+	BUG_ON(ret);
+	write_ctree_super(trans, root, 0);
+
+	/*
+	 * the super is written, we can safely allow the tree-loggers
+	 * to go about their business
+	 */
+	mutex_unlock(&root->fs_info->tree_log_mutex);
+
+	btrfs_finish_extent_commit(trans, root, pinned_copy);
+	kfree(pinned_copy);
+
+	btrfs_drop_dead_reloc_roots(root);
+	mutex_unlock(&root->fs_info->tree_reloc_mutex);
+
+	/* do the directory inserts of any pending snapshot creations */
+	finish_pending_snapshots(trans, root->fs_info);
+
+	mutex_lock(&root->fs_info->trans_mutex);
+
+	cur_trans->commit_done = 1;
+	root->fs_info->last_trans_committed = cur_trans->transid;
+	wake_up(&cur_trans->commit_wait);
+
+	put_transaction(cur_trans);
+	put_transaction(cur_trans);
+
+	list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
+	if (root->fs_info->closing)
+		list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
+
+	mutex_unlock(&root->fs_info->trans_mutex);
+
+	kmem_cache_free(btrfs_trans_handle_cachep, trans);
+
+	if (root->fs_info->closing)
+		drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
+	return ret;
+}
+
+/*
+ * interface function to delete all the snapshots we have scheduled for deletion
+ */
+int btrfs_clean_old_snapshots(struct btrfs_root *root)
+{
+	struct list_head dirty_roots;
+	INIT_LIST_HEAD(&dirty_roots);
+again:
+	mutex_lock(&root->fs_info->trans_mutex);
+	list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
+	mutex_unlock(&root->fs_info->trans_mutex);
+
+	if (!list_empty(&dirty_roots)) {
+		drop_dirty_roots(root, &dirty_roots);
+		goto again;
+	}
+	return 0;
+}