Initial file dump from open source releaseHEADmaster

1 files changed, 4201 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
new file mode 100644
index 00000000..783906c6
--- /dev/null
+++ b/fs/btrfs/ioctl.c
@@ -0,0 +1,4201 @@
+/*
+ * 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/kernel.h>
+#include <linux/bio.h>
+#include <linux/buffer_head.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/mount.h>
+#include <linux/mpage.h>
+#include <linux/namei.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/statfs.h>
+#include <linux/compat.h>
+#include <linux/bit_spinlock.h>
+#include <linux/security.h>
+#include <linux/xattr.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/uuid.h>
+#include <linux/btrfs.h>
+#include "compat.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "print-tree.h"
+#include "volumes.h"
+#include "locking.h"
+#include "inode-map.h"
+#include "backref.h"
+#include "rcu-string.h"
+#include "send.h"
+#include "dev-replace.h"
+
+/* Mask out flags that are inappropriate for the given type of inode. */
+static inline __u32 btrfs_mask_flags(umode_t mode, __u32 flags)
+{
+	if (S_ISDIR(mode))
+		return flags;
+	else if (S_ISREG(mode))
+		return flags & ~FS_DIRSYNC_FL;
+	else
+		return flags & (FS_NODUMP_FL | FS_NOATIME_FL);
+}
+
+/*
+ * Export inode flags to the format expected by the FS_IOC_GETFLAGS ioctl.
+ */
+static unsigned int btrfs_flags_to_ioctl(unsigned int flags)
+{
+	unsigned int iflags = 0;
+
+	if (flags & BTRFS_INODE_SYNC)
+		iflags |= FS_SYNC_FL;
+	if (flags & BTRFS_INODE_IMMUTABLE)
+		iflags |= FS_IMMUTABLE_FL;
+	if (flags & BTRFS_INODE_APPEND)
+		iflags |= FS_APPEND_FL;
+	if (flags & BTRFS_INODE_NODUMP)
+		iflags |= FS_NODUMP_FL;
+	if (flags & BTRFS_INODE_NOATIME)
+		iflags |= FS_NOATIME_FL;
+	if (flags & BTRFS_INODE_DIRSYNC)
+		iflags |= FS_DIRSYNC_FL;
+	if (flags & BTRFS_INODE_NODATACOW)
+		iflags |= FS_NOCOW_FL;
+
+	if ((flags & BTRFS_INODE_COMPRESS) && !(flags & BTRFS_INODE_NOCOMPRESS))
+		iflags |= FS_COMPR_FL;
+	else if (flags & BTRFS_INODE_NOCOMPRESS)
+		iflags |= FS_NOCOMP_FL;
+
+	return iflags;
+}
+
+/*
+ * Update inode->i_flags based on the btrfs internal flags.
+ */
+void btrfs_update_iflags(struct inode *inode)
+{
+	struct btrfs_inode *ip = BTRFS_I(inode);
+
+	inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
+
+	if (ip->flags & BTRFS_INODE_SYNC)
+		inode->i_flags |= S_SYNC;
+	if (ip->flags & BTRFS_INODE_IMMUTABLE)
+		inode->i_flags |= S_IMMUTABLE;
+	if (ip->flags & BTRFS_INODE_APPEND)
+		inode->i_flags |= S_APPEND;
+	if (ip->flags & BTRFS_INODE_NOATIME)
+		inode->i_flags |= S_NOATIME;
+	if (ip->flags & BTRFS_INODE_DIRSYNC)
+		inode->i_flags |= S_DIRSYNC;
+}
+
+/*
+ * Inherit flags from the parent inode.
+ *
+ * Currently only the compression flags and the cow flags are inherited.
+ */
+void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
+{
+	unsigned int flags;
+
+	if (!dir)
+		return;
+
+	flags = BTRFS_I(dir)->flags;
+
+	if (flags & BTRFS_INODE_NOCOMPRESS) {
+		BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
+		BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
+	} else if (flags & BTRFS_INODE_COMPRESS) {
+		BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
+		BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
+	}
+
+	if (flags & BTRFS_INODE_NODATACOW) {
+		BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
+		if (S_ISREG(inode->i_mode))
+			BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
+	}
+
+	btrfs_update_iflags(inode);
+}
+
+static int btrfs_ioctl_getflags(struct file *file, void __user *arg)
+{
+	struct btrfs_inode *ip = BTRFS_I(file_inode(file));
+	unsigned int flags = btrfs_flags_to_ioctl(ip->flags);
+
+	if (copy_to_user(arg, &flags, sizeof(flags)))
+		return -EFAULT;
+	return 0;
+}
+
+static int check_flags(unsigned int flags)
+{
+	if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
+		      FS_NOATIME_FL | FS_NODUMP_FL | \
+		      FS_SYNC_FL | FS_DIRSYNC_FL | \
+		      FS_NOCOMP_FL | FS_COMPR_FL |
+		      FS_NOCOW_FL))
+		return -EOPNOTSUPP;
+
+	if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_inode *ip = BTRFS_I(inode);
+	struct btrfs_root *root = ip->root;
+	struct btrfs_trans_handle *trans;
+	unsigned int flags, oldflags;
+	int ret;
+	u64 ip_oldflags;
+	unsigned int i_oldflags;
+	umode_t mode;
+
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+
+	if (copy_from_user(&flags, arg, sizeof(flags)))
+		return -EFAULT;
+
+	ret = check_flags(flags);
+	if (ret)
+		return ret;
+
+	if (!inode_owner_or_capable(inode))
+		return -EACCES;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	mutex_lock(&inode->i_mutex);
+
+	ip_oldflags = ip->flags;
+	i_oldflags = inode->i_flags;
+	mode = inode->i_mode;
+
+	flags = btrfs_mask_flags(inode->i_mode, flags);
+	oldflags = btrfs_flags_to_ioctl(ip->flags);
+	if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) {
+		if (!capable(CAP_LINUX_IMMUTABLE)) {
+			ret = -EPERM;
+			goto out_unlock;
+		}
+	}
+
+	if (flags & FS_SYNC_FL)
+		ip->flags |= BTRFS_INODE_SYNC;
+	else
+		ip->flags &= ~BTRFS_INODE_SYNC;
+	if (flags & FS_IMMUTABLE_FL)
+		ip->flags |= BTRFS_INODE_IMMUTABLE;
+	else
+		ip->flags &= ~BTRFS_INODE_IMMUTABLE;
+	if (flags & FS_APPEND_FL)
+		ip->flags |= BTRFS_INODE_APPEND;
+	else
+		ip->flags &= ~BTRFS_INODE_APPEND;
+	if (flags & FS_NODUMP_FL)
+		ip->flags |= BTRFS_INODE_NODUMP;
+	else
+		ip->flags &= ~BTRFS_INODE_NODUMP;
+	if (flags & FS_NOATIME_FL)
+		ip->flags |= BTRFS_INODE_NOATIME;
+	else
+		ip->flags &= ~BTRFS_INODE_NOATIME;
+	if (flags & FS_DIRSYNC_FL)
+		ip->flags |= BTRFS_INODE_DIRSYNC;
+	else
+		ip->flags &= ~BTRFS_INODE_DIRSYNC;
+	if (flags & FS_NOCOW_FL) {
+		if (S_ISREG(mode)) {
+			/*
+			 * It's safe to turn csums off here, no extents exist.
+			 * Otherwise we want the flag to reflect the real COW
+			 * status of the file and will not set it.
+			 */
+			if (inode->i_size == 0)
+				ip->flags |= BTRFS_INODE_NODATACOW
+					   | BTRFS_INODE_NODATASUM;
+		} else {
+			ip->flags |= BTRFS_INODE_NODATACOW;
+		}
+	} else {
+		/*
+		 * Revert back under same assuptions as above
+		 */
+		if (S_ISREG(mode)) {
+			if (inode->i_size == 0)
+				ip->flags &= ~(BTRFS_INODE_NODATACOW
+				             | BTRFS_INODE_NODATASUM);
+		} else {
+			ip->flags &= ~BTRFS_INODE_NODATACOW;
+		}
+	}
+
+	/*
+	 * The COMPRESS flag can only be changed by users, while the NOCOMPRESS
+	 * flag may be changed automatically if compression code won't make
+	 * things smaller.
+	 */
+	if (flags & FS_NOCOMP_FL) {
+		ip->flags &= ~BTRFS_INODE_COMPRESS;
+		ip->flags |= BTRFS_INODE_NOCOMPRESS;
+	} else if (flags & FS_COMPR_FL) {
+		ip->flags |= BTRFS_INODE_COMPRESS;
+		ip->flags &= ~BTRFS_INODE_NOCOMPRESS;
+	} else {
+		ip->flags &= ~(BTRFS_INODE_COMPRESS | BTRFS_INODE_NOCOMPRESS);
+	}
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_drop;
+	}
+
+	btrfs_update_iflags(inode);
+	inode_inc_iversion(inode);
+	inode->i_ctime = CURRENT_TIME;
+	ret = btrfs_update_inode(trans, root, inode);
+
+	btrfs_end_transaction(trans, root);
+ out_drop:
+	if (ret) {
+		ip->flags = ip_oldflags;
+		inode->i_flags = i_oldflags;
+	}
+
+ out_unlock:
+	mutex_unlock(&inode->i_mutex);
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static int btrfs_ioctl_getversion(struct file *file, int __user *arg)
+{
+	struct inode *inode = file_inode(file);
+
+	return put_user(inode->i_generation, arg);
+}
+
+static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
+{
+	struct btrfs_fs_info *fs_info = btrfs_sb(fdentry(file)->d_sb);
+	struct btrfs_device *device;
+	struct request_queue *q;
+	struct fstrim_range range;
+	u64 minlen = ULLONG_MAX;
+	u64 num_devices = 0;
+	u64 total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(device, &fs_info->fs_devices->devices,
+				dev_list) {
+		if (!device->bdev)
+			continue;
+		q = bdev_get_queue(device->bdev);
+		if (blk_queue_discard(q)) {
+			num_devices++;
+			minlen = min((u64)q->limits.discard_granularity,
+				     minlen);
+		}
+	}
+	rcu_read_unlock();
+
+	if (!num_devices)
+		return -EOPNOTSUPP;
+	if (copy_from_user(&range, arg, sizeof(range)))
+		return -EFAULT;
+	if (range.start > total_bytes ||
+	    range.len < fs_info->sb->s_blocksize)
+		return -EINVAL;
+
+	range.len = min(range.len, total_bytes - range.start);
+	range.minlen = max(range.minlen, minlen);
+	ret = btrfs_trim_fs(fs_info->tree_root, &range);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(arg, &range, sizeof(range)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static noinline int create_subvol(struct inode *dir,
+				  struct dentry *dentry,
+				  char *name, int namelen,
+				  u64 *async_transid,
+				  struct btrfs_qgroup_inherit *inherit)
+{
+	struct btrfs_trans_handle *trans;
+	struct btrfs_key key;
+	struct btrfs_root_item root_item;
+	struct btrfs_inode_item *inode_item;
+	struct extent_buffer *leaf;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_root *new_root;
+	struct btrfs_block_rsv block_rsv;
+	struct timespec cur_time = CURRENT_TIME;
+	int ret;
+	int err;
+	u64 objectid;
+	u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
+	u64 index = 0;
+	u64 qgroup_reserved;
+	uuid_le new_uuid;
+
+	ret = btrfs_find_free_objectid(root->fs_info->tree_root, &objectid);
+	if (ret)
+		return ret;
+
+	btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
+	/*
+	 * The same as the snapshot creation, please see the comment
+	 * of create_snapshot().
+	 */
+	ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
+					       7, &qgroup_reserved);
+	if (ret)
+		return ret;
+
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+	trans->block_rsv = &block_rsv;
+	trans->bytes_reserved = block_rsv.size;
+
+	ret = btrfs_qgroup_inherit(trans, root->fs_info, 0, objectid, inherit);
+	if (ret)
+		goto fail;
+
+	leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
+				      0, objectid, NULL, 0, 0, 0);
+	if (IS_ERR(leaf)) {
+		ret = PTR_ERR(leaf);
+		goto fail;
+	}
+
+	memset_extent_buffer(leaf, 0, 0, sizeof(struct btrfs_header));
+	btrfs_set_header_bytenr(leaf, leaf->start);
+	btrfs_set_header_generation(leaf, trans->transid);
+	btrfs_set_header_backref_rev(leaf, BTRFS_MIXED_BACKREF_REV);
+	btrfs_set_header_owner(leaf, objectid);
+
+	write_extent_buffer(leaf, root->fs_info->fsid,
+			    (unsigned long)btrfs_header_fsid(leaf),
+			    BTRFS_FSID_SIZE);
+	write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,
+			    (unsigned long)btrfs_header_chunk_tree_uuid(leaf),
+			    BTRFS_UUID_SIZE);
+	btrfs_mark_buffer_dirty(leaf);
+
+	memset(&root_item, 0, sizeof(root_item));
+
+	inode_item = &root_item.inode;
+	inode_item->generation = cpu_to_le64(1);
+	inode_item->size = cpu_to_le64(3);
+	inode_item->nlink = cpu_to_le32(1);
+	inode_item->nbytes = cpu_to_le64(root->leafsize);
+	inode_item->mode = cpu_to_le32(S_IFDIR | 0755);
+
+	root_item.flags = 0;
+	root_item.byte_limit = 0;
+	inode_item->flags = cpu_to_le64(BTRFS_INODE_ROOT_ITEM_INIT);
+
+	btrfs_set_root_bytenr(&root_item, leaf->start);
+	btrfs_set_root_generation(&root_item, trans->transid);
+	btrfs_set_root_level(&root_item, 0);
+	btrfs_set_root_refs(&root_item, 1);
+	btrfs_set_root_used(&root_item, leaf->len);
+	btrfs_set_root_last_snapshot(&root_item, 0);
+
+	btrfs_set_root_generation_v2(&root_item,
+			btrfs_root_generation(&root_item));
+	uuid_le_gen(&new_uuid);
+	memcpy(root_item.uuid, new_uuid.b, BTRFS_UUID_SIZE);
+	root_item.otime.sec = cpu_to_le64(cur_time.tv_sec);
+	root_item.otime.nsec = cpu_to_le32(cur_time.tv_nsec);
+	root_item.ctime = root_item.otime;
+	btrfs_set_root_ctransid(&root_item, trans->transid);
+	btrfs_set_root_otransid(&root_item, trans->transid);
+
+	btrfs_tree_unlock(leaf);
+	free_extent_buffer(leaf);
+	leaf = NULL;
+
+	btrfs_set_root_dirid(&root_item, new_dirid);
+
+	key.objectid = objectid;
+	key.offset = 0;
+	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+	ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
+				&root_item);
+	if (ret)
+		goto fail;
+
+	key.offset = (u64)-1;
+	new_root = btrfs_read_fs_root_no_name(root->fs_info, &key);
+	if (IS_ERR(new_root)) {
+		btrfs_abort_transaction(trans, root, PTR_ERR(new_root));
+		ret = PTR_ERR(new_root);
+		goto fail;
+	}
+
+	btrfs_record_root_in_trans(trans, new_root);
+
+	ret = btrfs_create_subvol_root(trans, new_root, new_dirid);
+	if (ret) {
+		/* We potentially lose an unused inode item here */
+		btrfs_abort_transaction(trans, root, ret);
+		goto fail;
+	}
+
+	/*
+	 * insert the directory item
+	 */
+	ret = btrfs_set_inode_index(dir, &index);
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		goto fail;
+	}
+
+	ret = btrfs_insert_dir_item(trans, root,
+				    name, namelen, dir, &key,
+				    BTRFS_FT_DIR, index);
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		goto fail;
+	}
+
+	btrfs_i_size_write(dir, dir->i_size + namelen * 2);
+	ret = btrfs_update_inode(trans, root, dir);
+	BUG_ON(ret);
+
+	ret = btrfs_add_root_ref(trans, root->fs_info->tree_root,
+				 objectid, root->root_key.objectid,
+				 btrfs_ino(dir), index, name, namelen);
+
+	BUG_ON(ret);
+
+fail:
+	trans->block_rsv = NULL;
+	trans->bytes_reserved = 0;
+	if (async_transid) {
+		*async_transid = trans->transid;
+		err = btrfs_commit_transaction_async(trans, root, 1);
+		if (err)
+			err = btrfs_commit_transaction(trans, root);
+	} else {
+		err = btrfs_commit_transaction(trans, root);
+	}
+	if (err && !ret)
+		ret = err;
+
+	if (!ret)
+		d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
+out:
+	btrfs_subvolume_release_metadata(root, &block_rsv, qgroup_reserved);
+	return ret;
+}
+
+static int create_snapshot(struct btrfs_root *root, struct inode *dir,
+			   struct dentry *dentry, char *name, int namelen,
+			   u64 *async_transid, bool readonly,
+			   struct btrfs_qgroup_inherit *inherit)
+{
+	struct inode *inode;
+	struct btrfs_pending_snapshot *pending_snapshot;
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	if (!root->ref_cows)
+		return -EINVAL;
+
+	pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_NOFS);
+	if (!pending_snapshot)
+		return -ENOMEM;
+
+	btrfs_init_block_rsv(&pending_snapshot->block_rsv,
+			     BTRFS_BLOCK_RSV_TEMP);
+	/*
+	 * 1 - parent dir inode
+	 * 2 - dir entries
+	 * 1 - root item
+	 * 2 - root ref/backref
+	 * 1 - root of snapshot
+	 */
+	ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
+					&pending_snapshot->block_rsv, 7,
+					&pending_snapshot->qgroup_reserved);
+	if (ret)
+		goto out;
+
+	pending_snapshot->dentry = dentry;
+	pending_snapshot->root = root;
+	pending_snapshot->readonly = readonly;
+	pending_snapshot->dir = dir;
+	pending_snapshot->inherit = inherit;
+
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto fail;
+	}
+
+	spin_lock(&root->fs_info->trans_lock);
+	list_add(&pending_snapshot->list,
+		 &trans->transaction->pending_snapshots);
+	spin_unlock(&root->fs_info->trans_lock);
+	if (async_transid) {
+		*async_transid = trans->transid;
+		ret = btrfs_commit_transaction_async(trans,
+				     root->fs_info->extent_root, 1);
+		if (ret)
+			ret = btrfs_commit_transaction(trans, root);
+	} else {
+		ret = btrfs_commit_transaction(trans,
+					       root->fs_info->extent_root);
+	}
+	if (ret)
+		goto fail;
+
+	ret = pending_snapshot->error;
+	if (ret)
+		goto fail;
+
+	ret = btrfs_orphan_cleanup(pending_snapshot->snap);
+	if (ret)
+		goto fail;
+
+	inode = btrfs_lookup_dentry(dentry->d_parent->d_inode, dentry);
+	if (IS_ERR(inode)) {
+		ret = PTR_ERR(inode);
+		goto fail;
+	}
+	BUG_ON(!inode);
+	d_instantiate(dentry, inode);
+	ret = 0;
+fail:
+	btrfs_subvolume_release_metadata(BTRFS_I(dir)->root,
+					 &pending_snapshot->block_rsv,
+					 pending_snapshot->qgroup_reserved);
+out:
+	kfree(pending_snapshot);
+	return ret;
+}
+
+/*  copy of check_sticky in fs/namei.c()
+* It's inline, so penalty for filesystems that don't use sticky bit is
+* minimal.
+*/
+static inline int btrfs_check_sticky(struct inode *dir, struct inode *inode)
+{
+	kuid_t fsuid = current_fsuid();
+
+	if (!(dir->i_mode & S_ISVTX))
+		return 0;
+	if (uid_eq(inode->i_uid, fsuid))
+		return 0;
+	if (uid_eq(dir->i_uid, fsuid))
+		return 0;
+	return !capable(CAP_FOWNER);
+}
+
+/*  copy of may_delete in fs/namei.c()
+ *	Check whether we can remove a link victim from directory dir, check
+ *  whether the type of victim is right.
+ *  1. We can't do it if dir is read-only (done in permission())
+ *  2. We should have write and exec permissions on dir
+ *  3. We can't remove anything from append-only dir
+ *  4. We can't do anything with immutable dir (done in permission())
+ *  5. If the sticky bit on dir is set we should either
+ *	a. be owner of dir, or
+ *	b. be owner of victim, or
+ *	c. have CAP_FOWNER capability
+ *  6. If the victim is append-only or immutable we can't do antyhing with
+ *     links pointing to it.
+ *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
+ *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
+ *  9. We can't remove a root or mountpoint.
+ * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
+ *     nfs_async_unlink().
+ */
+
+static int btrfs_may_delete(struct inode *dir,struct dentry *victim,int isdir)
+{
+	int error;
+
+	if (!victim->d_inode)
+		return -ENOENT;
+
+	BUG_ON(victim->d_parent->d_inode != dir);
+	audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
+
+	error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
+	if (error)
+		return error;
+	if (IS_APPEND(dir))
+		return -EPERM;
+	if (btrfs_check_sticky(dir, victim->d_inode)||
+		IS_APPEND(victim->d_inode)||
+	    IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
+		return -EPERM;
+	if (isdir) {
+		if (!S_ISDIR(victim->d_inode->i_mode))
+			return -ENOTDIR;
+		if (IS_ROOT(victim))
+			return -EBUSY;
+	} else if (S_ISDIR(victim->d_inode->i_mode))
+		return -EISDIR;
+	if (IS_DEADDIR(dir))
+		return -ENOENT;
+	if (victim->d_flags & DCACHE_NFSFS_RENAMED)
+		return -EBUSY;
+	return 0;
+}
+
+/* copy of may_create in fs/namei.c() */
+static inline int btrfs_may_create(struct inode *dir, struct dentry *child)
+{
+	if (child->d_inode)
+		return -EEXIST;
+	if (IS_DEADDIR(dir))
+		return -ENOENT;
+	return inode_permission(dir, MAY_WRITE | MAY_EXEC);
+}
+
+/*
+ * Create a new subvolume below @parent.  This is largely modeled after
+ * sys_mkdirat and vfs_mkdir, but we only do a single component lookup
+ * inside this filesystem so it's quite a bit simpler.
+ */
+static noinline int btrfs_mksubvol(struct path *parent,
+				   char *name, int namelen,
+				   struct btrfs_root *snap_src,
+				   u64 *async_transid, bool readonly,
+				   struct btrfs_qgroup_inherit *inherit)
+{
+	struct inode *dir  = parent->dentry->d_inode;
+	struct dentry *dentry;
+	int error;
+
+	error = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
+	if (error == -EINTR)
+		return error;
+
+	dentry = lookup_one_len(name, parent->dentry, namelen);
+	error = PTR_ERR(dentry);
+	if (IS_ERR(dentry))
+		goto out_unlock;
+
+	error = -EEXIST;
+	if (dentry->d_inode)
+		goto out_dput;
+
+	error = btrfs_may_create(dir, dentry);
+	if (error)
+		goto out_dput;
+
+	/*
+	 * even if this name doesn't exist, we may get hash collisions.
+	 * check for them now when we can safely fail
+	 */
+	error = btrfs_check_dir_item_collision(BTRFS_I(dir)->root,
+					       dir->i_ino, name,
+					       namelen);
+	if (error)
+		goto out_dput;
+
+	down_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);
+
+	if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
+		goto out_up_read;
+
+	if (snap_src) {
+		error = create_snapshot(snap_src, dir, dentry, name, namelen,
+					async_transid, readonly, inherit);
+	} else {
+		error = create_subvol(dir, dentry, name, namelen,
+				      async_transid, inherit);
+	}
+	if (!error)
+		fsnotify_mkdir(dir, dentry);
+out_up_read:
+	up_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);
+out_dput:
+	dput(dentry);
+out_unlock:
+	mutex_unlock(&dir->i_mutex);
+	return error;
+}
+
+/*
+ * When we're defragging a range, we don't want to kick it off again
+ * if it is really just waiting for delalloc to send it down.
+ * If we find a nice big extent or delalloc range for the bytes in the
+ * file you want to defrag, we return 0 to let you know to skip this
+ * part of the file
+ */
+static int check_defrag_in_cache(struct inode *inode, u64 offset, int thresh)
+{
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_map *em = NULL;
+	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	u64 end;
+
+	read_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, offset, PAGE_CACHE_SIZE);
+	read_unlock(&em_tree->lock);
+
+	if (em) {
+		end = extent_map_end(em);
+		free_extent_map(em);
+		if (end - offset > thresh)
+			return 0;
+	}
+	/* if we already have a nice delalloc here, just stop */
+	thresh /= 2;
+	end = count_range_bits(io_tree, &offset, offset + thresh,
+			       thresh, EXTENT_DELALLOC, 1);
+	if (end >= thresh)
+		return 0;
+	return 1;
+}
+
+/*
+ * helper function to walk through a file and find extents
+ * newer than a specific transid, and smaller than thresh.
+ *
+ * This is used by the defragging code to find new and small
+ * extents
+ */
+static int find_new_extents(struct btrfs_root *root,
+			    struct inode *inode, u64 newer_than,
+			    u64 *off, int thresh)
+{
+	struct btrfs_path *path;
+	struct btrfs_key min_key;
+	struct btrfs_key max_key;
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *extent;
+	int type;
+	int ret;
+	u64 ino = btrfs_ino(inode);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	min_key.objectid = ino;
+	min_key.type = BTRFS_EXTENT_DATA_KEY;
+	min_key.offset = *off;
+
+	max_key.objectid = ino;
+	max_key.type = (u8)-1;
+	max_key.offset = (u64)-1;
+
+	path->keep_locks = 1;
+
+	while(1) {
+		ret = btrfs_search_forward(root, &min_key, &max_key,
+					   path, newer_than);
+		if (ret != 0)
+			goto none;
+		if (min_key.objectid != ino)
+			goto none;
+		if (min_key.type != BTRFS_EXTENT_DATA_KEY)
+			goto none;
+
+		leaf = path->nodes[0];
+		extent = btrfs_item_ptr(leaf, path->slots[0],
+					struct btrfs_file_extent_item);
+
+		type = btrfs_file_extent_type(leaf, extent);
+		if (type == BTRFS_FILE_EXTENT_REG &&
+		    btrfs_file_extent_num_bytes(leaf, extent) < thresh &&
+		    check_defrag_in_cache(inode, min_key.offset, thresh)) {
+			*off = min_key.offset;
+			btrfs_free_path(path);
+			return 0;
+		}
+
+		if (min_key.offset == (u64)-1)
+			goto none;
+
+		min_key.offset++;
+		btrfs_release_path(path);
+	}
+none:
+	btrfs_free_path(path);
+	return -ENOENT;
+}
+
+static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start)
+{
+	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct extent_map *em;
+	u64 len = PAGE_CACHE_SIZE;
+
+	/*
+	 * hopefully we have this extent in the tree already, try without
+	 * the full extent lock
+	 */
+	read_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, start, len);
+	read_unlock(&em_tree->lock);
+
+	if (!em) {
+		/* get the big lock and read metadata off disk */
+		lock_extent(io_tree, start, start + len - 1);
+		em = btrfs_get_extent(inode, NULL, 0, start, len, 0);
+		unlock_extent(io_tree, start, start + len - 1);
+
+		if (IS_ERR(em))
+			return NULL;
+	}
+
+	return em;
+}
+
+static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em)
+{
+	struct extent_map *next;
+	bool ret = true;
+
+	/* this is the last extent */
+	if (em->start + em->len >= i_size_read(inode))
+		return false;
+
+	next = defrag_lookup_extent(inode, em->start + em->len);
+	if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
+		ret = false;
+
+	free_extent_map(next);
+	return ret;
+}
+
+static int should_defrag_range(struct inode *inode, u64 start, int thresh,
+			       u64 *last_len, u64 *skip, u64 *defrag_end,
+			       int compress)
+{
+	struct extent_map *em;
+	int ret = 1;
+	bool next_mergeable = true;
+
+	/*
+	 * make sure that once we start defragging an extent, we keep on
+	 * defragging it
+	 */
+	if (start < *defrag_end)
+		return 1;
+
+	*skip = 0;
+
+	em = defrag_lookup_extent(inode, start);
+	if (!em)
+		return 0;
+
+	/* this will cover holes, and inline extents */
+	if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
+		ret = 0;
+		goto out;
+	}
+
+	next_mergeable = defrag_check_next_extent(inode, em);
+
+	/*
+	 * we hit a real extent, if it is big or the next extent is not a
+	 * real extent, don't bother defragging it
+	 */
+	if (!compress && (*last_len == 0 || *last_len >= thresh) &&
+	    (em->len >= thresh || !next_mergeable))
+		ret = 0;
+out:
+	/*
+	 * last_len ends up being a counter of how many bytes we've defragged.
+	 * every time we choose not to defrag an extent, we reset *last_len
+	 * so that the next tiny extent will force a defrag.
+	 *
+	 * The end result of this is that tiny extents before a single big
+	 * extent will force at least part of that big extent to be defragged.
+	 */
+	if (ret) {
+		*defrag_end = extent_map_end(em);
+	} else {
+		*last_len = 0;
+		*skip = extent_map_end(em);
+		*defrag_end = 0;
+	}
+
+	free_extent_map(em);
+	return ret;
+}
+
+/*
+ * it doesn't do much good to defrag one or two pages
+ * at a time.  This pulls in a nice chunk of pages
+ * to COW and defrag.
+ *
+ * It also makes sure the delalloc code has enough
+ * dirty data to avoid making new small extents as part
+ * of the defrag
+ *
+ * It's a good idea to start RA on this range
+ * before calling this.
+ */
+static int cluster_pages_for_defrag(struct inode *inode,
+				    struct page **pages,
+				    unsigned long start_index,
+				    int num_pages)
+{
+	unsigned long file_end;
+	u64 isize = i_size_read(inode);
+	u64 page_start;
+	u64 page_end;
+	u64 page_cnt;
+	int ret;
+	int i;
+	int i_done;
+	struct btrfs_ordered_extent *ordered;
+	struct extent_state *cached_state = NULL;
+	struct extent_io_tree *tree;
+	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
+
+	file_end = (isize - 1) >> PAGE_CACHE_SHIFT;
+	if (!isize || start_index > file_end)
+		return 0;
+
+	page_cnt = min_t(u64, (u64)num_pages, (u64)file_end - start_index + 1);
+
+	ret = btrfs_delalloc_reserve_space(inode,
+					   page_cnt << PAGE_CACHE_SHIFT);
+	if (ret)
+		return ret;
+	i_done = 0;
+	tree = &BTRFS_I(inode)->io_tree;
+
+	/* step one, lock all the pages */
+	for (i = 0; i < page_cnt; i++) {
+		struct page *page;
+again:
+		page = find_or_create_page(inode->i_mapping,
+					   start_index + i, mask);
+		if (!page)
+			break;
+
+		page_start = page_offset(page);
+		page_end = page_start + PAGE_CACHE_SIZE - 1;
+		while (1) {
+			lock_extent(tree, page_start, page_end);
+			ordered = btrfs_lookup_ordered_extent(inode,
+							      page_start);
+			unlock_extent(tree, page_start, page_end);
+			if (!ordered)
+				break;
+
+			unlock_page(page);
+			btrfs_start_ordered_extent(inode, ordered, 1);
+			btrfs_put_ordered_extent(ordered);
+			lock_page(page);
+			/*
+			 * we unlocked the page above, so we need check if
+			 * it was released or not.
+			 */
+			if (page->mapping != inode->i_mapping) {
+				unlock_page(page);
+				page_cache_release(page);
+				goto again;
+			}
+		}
+
+		if (!PageUptodate(page)) {
+			btrfs_readpage(NULL, page);
+			lock_page(page);
+			if (!PageUptodate(page)) {
+				unlock_page(page);
+				page_cache_release(page);
+				ret = -EIO;
+				break;
+			}
+		}
+
+		if (page->mapping != inode->i_mapping) {
+			unlock_page(page);
+			page_cache_release(page);
+			goto again;
+		}
+
+		pages[i] = page;
+		i_done++;
+	}
+	if (!i_done || ret)
+		goto out;
+
+	if (!(inode->i_sb->s_flags & MS_ACTIVE))
+		goto out;
+
+	/*
+	 * so now we have a nice long stream of locked
+	 * and up to date pages, lets wait on them
+	 */
+	for (i = 0; i < i_done; i++)
+		wait_on_page_writeback(pages[i]);
+
+	page_start = page_offset(pages[0]);
+	page_end = page_offset(pages[i_done - 1]) + PAGE_CACHE_SIZE;
+
+	lock_extent_bits(&BTRFS_I(inode)->io_tree,
+			 page_start, page_end - 1, 0, &cached_state);
+	clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start,
+			  page_end - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
+			  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0,
+			  &cached_state, GFP_NOFS);
+
+	if (i_done != page_cnt) {
+		spin_lock(&BTRFS_I(inode)->lock);
+		BTRFS_I(inode)->outstanding_extents++;
+		spin_unlock(&BTRFS_I(inode)->lock);
+		btrfs_delalloc_release_space(inode,
+				     (page_cnt - i_done) << PAGE_CACHE_SHIFT);
+	}
+
+
+	set_extent_defrag(&BTRFS_I(inode)->io_tree, page_start, page_end - 1,
+			  &cached_state, GFP_NOFS);
+
+	unlock_extent_cached(&BTRFS_I(inode)->io_tree,
+			     page_start, page_end - 1, &cached_state,
+			     GFP_NOFS);
+
+	for (i = 0; i < i_done; i++) {
+		clear_page_dirty_for_io(pages[i]);
+		ClearPageChecked(pages[i]);
+		set_page_extent_mapped(pages[i]);
+		set_page_dirty(pages[i]);
+		unlock_page(pages[i]);
+		page_cache_release(pages[i]);
+	}
+	return i_done;
+out:
+	for (i = 0; i < i_done; i++) {
+		unlock_page(pages[i]);
+		page_cache_release(pages[i]);
+	}
+	btrfs_delalloc_release_space(inode, page_cnt << PAGE_CACHE_SHIFT);
+	return ret;
+
+}
+
+int btrfs_defrag_file(struct inode *inode, struct file *file,
+		      struct btrfs_ioctl_defrag_range_args *range,
+		      u64 newer_than, unsigned long max_to_defrag)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct file_ra_state *ra = NULL;
+	unsigned long last_index;
+	u64 isize = i_size_read(inode);
+	u64 last_len = 0;
+	u64 skip = 0;
+	u64 defrag_end = 0;
+	u64 newer_off = range->start;
+	unsigned long i;
+	unsigned long ra_index = 0;
+	int ret;
+	int defrag_count = 0;
+	int compress_type = BTRFS_COMPRESS_ZLIB;
+	int extent_thresh = range->extent_thresh;
+	int max_cluster = (256 * 1024) >> PAGE_CACHE_SHIFT;
+	int cluster = max_cluster;
+	u64 new_align = ~((u64)128 * 1024 - 1);
+	struct page **pages = NULL;
+
+	if (isize == 0)
+		return 0;
+
+	if (range->start >= isize)
+		return -EINVAL;
+
+	if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS) {
+		if (range->compress_type > BTRFS_COMPRESS_TYPES)
+			return -EINVAL;
+		if (range->compress_type)
+			compress_type = range->compress_type;
+	}
+
+	if (extent_thresh == 0)
+		extent_thresh = 256 * 1024;
+
+	/*
+	 * if we were not given a file, allocate a readahead
+	 * context
+	 */
+	if (!file) {
+		ra = kzalloc(sizeof(*ra), GFP_NOFS);
+		if (!ra)
+			return -ENOMEM;
+		file_ra_state_init(ra, inode->i_mapping);
+	} else {
+		ra = &file->f_ra;
+	}
+
+	pages = kmalloc(sizeof(struct page *) * max_cluster,
+			GFP_NOFS);
+	if (!pages) {
+		ret = -ENOMEM;
+		goto out_ra;
+	}
+
+	/* find the last page to defrag */
+	if (range->start + range->len > range->start) {
+		last_index = min_t(u64, isize - 1,
+			 range->start + range->len - 1) >> PAGE_CACHE_SHIFT;
+	} else {
+		last_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+	}
+
+	if (newer_than) {
+		ret = find_new_extents(root, inode, newer_than,
+				       &newer_off, 64 * 1024);
+		if (!ret) {
+			range->start = newer_off;
+			/*
+			 * we always align our defrag to help keep
+			 * the extents in the file evenly spaced
+			 */
+			i = (newer_off & new_align) >> PAGE_CACHE_SHIFT;
+		} else
+			goto out_ra;
+	} else {
+		i = range->start >> PAGE_CACHE_SHIFT;
+	}
+	if (!max_to_defrag)
+		max_to_defrag = last_index + 1;
+
+	/*
+	 * make writeback starts from i, so the defrag range can be
+	 * written sequentially.
+	 */
+	if (i < inode->i_mapping->writeback_index)
+		inode->i_mapping->writeback_index = i;
+
+	while (i <= last_index && defrag_count < max_to_defrag &&
+	       (i < (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+		PAGE_CACHE_SHIFT)) {
+		/*
+		 * make sure we stop running if someone unmounts
+		 * the FS
+		 */
+		if (!(inode->i_sb->s_flags & MS_ACTIVE))
+			break;
+
+		if (btrfs_defrag_cancelled(root->fs_info)) {
+			printk(KERN_DEBUG "btrfs: defrag_file cancelled\n");
+			ret = -EAGAIN;
+			break;
+		}
+
+		if (!should_defrag_range(inode, (u64)i << PAGE_CACHE_SHIFT,
+					 extent_thresh, &last_len, &skip,
+					 &defrag_end, range->flags &
+					 BTRFS_DEFRAG_RANGE_COMPRESS)) {
+			unsigned long next;
+			/*
+			 * the should_defrag function tells us how much to skip
+			 * bump our counter by the suggested amount
+			 */
+			next = (skip + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+			i = max(i + 1, next);
+			continue;
+		}
+
+		if (!newer_than) {
+			cluster = (PAGE_CACHE_ALIGN(defrag_end) >>
+				   PAGE_CACHE_SHIFT) - i;
+			cluster = min(cluster, max_cluster);
+		} else {
+			cluster = max_cluster;
+		}
+
+		if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)
+			BTRFS_I(inode)->force_compress = compress_type;
+
+		if (i + cluster > ra_index) {
+			ra_index = max(i, ra_index);
+			btrfs_force_ra(inode->i_mapping, ra, file, ra_index,
+				       cluster);
+			ra_index += max_cluster;
+		}
+
+		mutex_lock(&inode->i_mutex);
+		ret = cluster_pages_for_defrag(inode, pages, i, cluster);
+		if (ret < 0) {
+			mutex_unlock(&inode->i_mutex);
+			goto out_ra;
+		}
+
+		defrag_count += ret;
+		balance_dirty_pages_ratelimited(inode->i_mapping);
+		mutex_unlock(&inode->i_mutex);
+
+		if (newer_than) {
+			if (newer_off == (u64)-1)
+				break;
+
+			if (ret > 0)
+				i += ret;
+
+			newer_off = max(newer_off + 1,
+					(u64)i << PAGE_CACHE_SHIFT);
+
+			ret = find_new_extents(root, inode,
+					       newer_than, &newer_off,
+					       64 * 1024);
+			if (!ret) {
+				range->start = newer_off;
+				i = (newer_off & new_align) >> PAGE_CACHE_SHIFT;
+			} else {
+				break;
+			}
+		} else {
+			if (ret > 0) {
+				i += ret;
+				last_len += ret << PAGE_CACHE_SHIFT;
+			} else {
+				i++;
+				last_len = 0;
+			}
+		}
+	}
+
+	if ((range->flags & BTRFS_DEFRAG_RANGE_START_IO))
+		filemap_flush(inode->i_mapping);
+
+	if ((range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
+		/* the filemap_flush will queue IO into the worker threads, but
+		 * we have to make sure the IO is actually started and that
+		 * ordered extents get created before we return
+		 */
+		atomic_inc(&root->fs_info->async_submit_draining);
+		while (atomic_read(&root->fs_info->nr_async_submits) ||
+		      atomic_read(&root->fs_info->async_delalloc_pages)) {
+			wait_event(root->fs_info->async_submit_wait,
+			   (atomic_read(&root->fs_info->nr_async_submits) == 0 &&
+			    atomic_read(&root->fs_info->async_delalloc_pages) == 0));
+		}
+		atomic_dec(&root->fs_info->async_submit_draining);
+
+		mutex_lock(&inode->i_mutex);
+		BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_NONE;
+		mutex_unlock(&inode->i_mutex);
+	}
+
+	if (range->compress_type == BTRFS_COMPRESS_LZO) {
+		btrfs_set_fs_incompat(root->fs_info, COMPRESS_LZO);
+	}
+
+	ret = defrag_count;
+
+out_ra:
+	if (!file)
+		kfree(ra);
+	kfree(pages);
+	return ret;
+}
+
+static noinline int btrfs_ioctl_resize(struct file *file,
+					void __user *arg)
+{
+	u64 new_size;
+	u64 old_size;
+	u64 devid = 1;
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_ioctl_vol_args *vol_args;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_device *device = NULL;
+	char *sizestr;
+	char *devstr = NULL;
+	int ret = 0;
+	int mod = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+			1)) {
+		pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+		mnt_drop_write_file(file);
+		return -EINVAL;
+	}
+
+	mutex_lock(&root->fs_info->volume_mutex);
+	vol_args = memdup_user(arg, sizeof(*vol_args));
+	if (IS_ERR(vol_args)) {
+		ret = PTR_ERR(vol_args);
+		goto out;
+	}
+
+	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+
+	sizestr = vol_args->name;
+	devstr = strchr(sizestr, ':');
+	if (devstr) {
+		char *end;
+		sizestr = devstr + 1;
+		*devstr = '\0';
+		devstr = vol_args->name;
+		devid = simple_strtoull(devstr, &end, 10);
+		if (!devid) {
+			ret = -EINVAL;
+			goto out_free;
+		}
+		printk(KERN_INFO "btrfs: resizing devid %llu\n",
+		       (unsigned long long)devid);
+	}
+
+	device = btrfs_find_device(root->fs_info, devid, NULL, NULL);
+	if (!device) {
+		printk(KERN_INFO "btrfs: resizer unable to find device %llu\n",
+		       (unsigned long long)devid);
+		ret = -ENODEV;
+		goto out_free;
+	}
+
+	if (!device->writeable) {
+		printk(KERN_INFO "btrfs: resizer unable to apply on "
+		       "readonly device %llu\n",
+		       (unsigned long long)devid);
+		ret = -EPERM;
+		goto out_free;
+	}
+
+	if (!strcmp(sizestr, "max"))
+		new_size = device->bdev->bd_inode->i_size;
+	else {
+		if (sizestr[0] == '-') {
+			mod = -1;
+			sizestr++;
+		} else if (sizestr[0] == '+') {
+			mod = 1;
+			sizestr++;
+		}
+		new_size = memparse(sizestr, NULL);
+		if (new_size == 0) {
+			ret = -EINVAL;
+			goto out_free;
+		}
+	}
+
+	if (device->is_tgtdev_for_dev_replace) {
+		ret = -EPERM;
+		goto out_free;
+	}
+
+	old_size = device->total_bytes;
+
+	if (mod < 0) {
+		if (new_size > old_size) {
+			ret = -EINVAL;
+			goto out_free;
+		}
+		new_size = old_size - new_size;
+	} else if (mod > 0) {
+		new_size = old_size + new_size;
+	}
+
+	if (new_size < 256 * 1024 * 1024) {
+		ret = -EINVAL;
+		goto out_free;
+	}
+	if (new_size > device->bdev->bd_inode->i_size) {
+		ret = -EFBIG;
+		goto out_free;
+	}
+
+	do_div(new_size, root->sectorsize);
+	new_size *= root->sectorsize;
+
+	printk_in_rcu(KERN_INFO "btrfs: new size for %s is %llu\n",
+		      rcu_str_deref(device->name),
+		      (unsigned long long)new_size);
+
+	if (new_size > old_size) {
+		trans = btrfs_start_transaction(root, 0);
+		if (IS_ERR(trans)) {
+			ret = PTR_ERR(trans);
+			goto out_free;
+		}
+		ret = btrfs_grow_device(trans, device, new_size);
+		btrfs_commit_transaction(trans, root);
+	} else if (new_size < old_size) {
+		ret = btrfs_shrink_device(device, new_size);
+	} /* equal, nothing need to do */
+
+out_free:
+	kfree(vol_args);
+out:
+	mutex_unlock(&root->fs_info->volume_mutex);
+	atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
+				char *name, unsigned long fd, int subvol,
+				u64 *transid, bool readonly,
+				struct btrfs_qgroup_inherit *inherit)
+{
+	int namelen;
+	int ret = 0;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		goto out;
+
+	namelen = strlen(name);
+	if (strchr(name, '/')) {
+		ret = -EINVAL;
+		goto out_drop_write;
+	}
+
+	if (name[0] == '.' &&
+	   (namelen == 1 || (name[1] == '.' && namelen == 2))) {
+		ret = -EEXIST;
+		goto out_drop_write;
+	}
+
+	if (subvol) {
+		ret = btrfs_mksubvol(&file->f_path, name, namelen,
+				     NULL, transid, readonly, inherit);
+	} else {
+		struct fd src = fdget(fd);
+		struct inode *src_inode;
+		if (!src.file) {
+			ret = -EINVAL;
+			goto out_drop_write;
+		}
+
+		src_inode = file_inode(src.file);
+		if (src_inode->i_sb != file_inode(file)->i_sb) {
+			printk(KERN_INFO "btrfs: Snapshot src from "
+			       "another FS\n");
+			ret = -EINVAL;
+		} else if (!inode_owner_or_capable(src_inode)) {
+			/*
+			 * Subvolume creation is not restricted, but snapshots
+			 * are limited to own subvolumes only
+			 */
+			ret = -EPERM;
+		} else {
+			ret = btrfs_mksubvol(&file->f_path, name, namelen,
+					     BTRFS_I(src_inode)->root,
+					     transid, readonly, inherit);
+		}
+		fdput(src);
+	}
+out_drop_write:
+	mnt_drop_write_file(file);
+out:
+	return ret;
+}
+
+static noinline int btrfs_ioctl_snap_create(struct file *file,
+					    void __user *arg, int subvol)
+{
+	struct btrfs_ioctl_vol_args *vol_args;
+	int ret;
+
+	vol_args = memdup_user(arg, sizeof(*vol_args));
+	if (IS_ERR(vol_args))
+		return PTR_ERR(vol_args);
+	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+
+	ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,
+					      vol_args->fd, subvol,
+					      NULL, false, NULL);
+
+	kfree(vol_args);
+	return ret;
+}
+
+static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
+					       void __user *arg, int subvol)
+{
+	struct btrfs_ioctl_vol_args_v2 *vol_args;
+	int ret;
+	u64 transid = 0;
+	u64 *ptr = NULL;
+	bool readonly = false;
+	struct btrfs_qgroup_inherit *inherit = NULL;
+
+	vol_args = memdup_user(arg, sizeof(*vol_args));
+	if (IS_ERR(vol_args))
+		return PTR_ERR(vol_args);
+	vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
+
+	if (vol_args->flags &
+	    ~(BTRFS_SUBVOL_CREATE_ASYNC | BTRFS_SUBVOL_RDONLY |
+	      BTRFS_SUBVOL_QGROUP_INHERIT)) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (vol_args->flags & BTRFS_SUBVOL_CREATE_ASYNC)
+		ptr = &transid;
+	if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
+		readonly = true;
+	if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
+		if (vol_args->size > PAGE_CACHE_SIZE) {
+			ret = -EINVAL;
+			goto out;
+		}
+		inherit = memdup_user(vol_args->qgroup_inherit, vol_args->size);
+		if (IS_ERR(inherit)) {
+			ret = PTR_ERR(inherit);
+			goto out;
+		}
+	}
+
+	ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,
+					      vol_args->fd, subvol, ptr,
+					      readonly, inherit);
+
+	if (ret == 0 && ptr &&
+	    copy_to_user(arg +
+			 offsetof(struct btrfs_ioctl_vol_args_v2,
+				  transid), ptr, sizeof(*ptr)))
+		ret = -EFAULT;
+out:
+	kfree(vol_args);
+	kfree(inherit);
+	return ret;
+}
+
+static noinline int btrfs_ioctl_subvol_getflags(struct file *file,
+						void __user *arg)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	int ret = 0;
+	u64 flags = 0;
+
+	if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID)
+		return -EINVAL;
+
+	down_read(&root->fs_info->subvol_sem);
+	if (btrfs_root_readonly(root))
+		flags |= BTRFS_SUBVOL_RDONLY;
+	up_read(&root->fs_info->subvol_sem);
+
+	if (copy_to_user(arg, &flags, sizeof(flags)))
+		ret = -EFAULT;
+
+	return ret;
+}
+
+static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
+					      void __user *arg)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+	u64 root_flags;
+	u64 flags;
+	int ret = 0;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		goto out;
+
+	if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) {
+		ret = -EINVAL;
+		goto out_drop_write;
+	}
+
+	if (copy_from_user(&flags, arg, sizeof(flags))) {
+		ret = -EFAULT;
+		goto out_drop_write;
+	}
+
+	if (flags & BTRFS_SUBVOL_CREATE_ASYNC) {
+		ret = -EINVAL;
+		goto out_drop_write;
+	}
+
+	if (flags & ~BTRFS_SUBVOL_RDONLY) {
+		ret = -EOPNOTSUPP;
+		goto out_drop_write;
+	}
+
+	if (!inode_owner_or_capable(inode)) {
+		ret = -EACCES;
+		goto out_drop_write;
+	}
+
+	down_write(&root->fs_info->subvol_sem);
+
+	/* nothing to do */
+	if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root))
+		goto out_drop_sem;
+
+	root_flags = btrfs_root_flags(&root->root_item);
+	if (flags & BTRFS_SUBVOL_RDONLY)
+		btrfs_set_root_flags(&root->root_item,
+				     root_flags | BTRFS_ROOT_SUBVOL_RDONLY);
+	else
+		btrfs_set_root_flags(&root->root_item,
+				     root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY);
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_reset;
+	}
+
+	ret = btrfs_update_root(trans, root->fs_info->tree_root,
+				&root->root_key, &root->root_item);
+
+	btrfs_commit_transaction(trans, root);
+out_reset:
+	if (ret)
+		btrfs_set_root_flags(&root->root_item, root_flags);
+out_drop_sem:
+	up_write(&root->fs_info->subvol_sem);
+out_drop_write:
+	mnt_drop_write_file(file);
+out:
+	return ret;
+}
+
+/*
+ * helper to check if the subvolume references other subvolumes
+ */
+static noinline int may_destroy_subvol(struct btrfs_root *root)
+{
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	key.objectid = root->root_key.objectid;
+	key.type = BTRFS_ROOT_REF_KEY;
+	key.offset = (u64)-1;
+
+	ret = btrfs_search_slot(NULL, root->fs_info->tree_root,
+				&key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+	BUG_ON(ret == 0);
+
+	ret = 0;
+	if (path->slots[0] > 0) {
+		path->slots[0]--;
+		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+		if (key.objectid == root->root_key.objectid &&
+		    key.type == BTRFS_ROOT_REF_KEY)
+			ret = -ENOTEMPTY;
+	}
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static noinline int key_in_sk(struct btrfs_key *key,
+			      struct btrfs_ioctl_search_key *sk)
+{
+	struct btrfs_key test;
+	int ret;
+
+	test.objectid = sk->min_objectid;
+	test.type = sk->min_type;
+	test.offset = sk->min_offset;
+
+	ret = btrfs_comp_cpu_keys(key, &test);
+	if (ret < 0)
+		return 0;
+
+	test.objectid = sk->max_objectid;
+	test.type = sk->max_type;
+	test.offset = sk->max_offset;
+
+	ret = btrfs_comp_cpu_keys(key, &test);
+	if (ret > 0)
+		return 0;
+	return 1;
+}
+
+static noinline int copy_to_sk(struct btrfs_root *root,
+			       struct btrfs_path *path,
+			       struct btrfs_key *key,
+			       struct btrfs_ioctl_search_key *sk,
+			       char *buf,
+			       unsigned long *sk_offset,
+			       int *num_found)
+{
+	u64 found_transid;
+	struct extent_buffer *leaf;
+	struct btrfs_ioctl_search_header sh;
+	unsigned long item_off;
+	unsigned long item_len;
+	int nritems;
+	int i;
+	int slot;
+	int ret = 0;
+
+	leaf = path->nodes[0];
+	slot = path->slots[0];
+	nritems = btrfs_header_nritems(leaf);
+
+	if (btrfs_header_generation(leaf) > sk->max_transid) {
+		i = nritems;
+		goto advance_key;
+	}
+	found_transid = btrfs_header_generation(leaf);
+
+	for (i = slot; i < nritems; i++) {
+		item_off = btrfs_item_ptr_offset(leaf, i);
+		item_len = btrfs_item_size_nr(leaf, i);
+
+		btrfs_item_key_to_cpu(leaf, key, i);
+		if (!key_in_sk(key, sk))
+			continue;
+
+		if (sizeof(sh) + item_len > BTRFS_SEARCH_ARGS_BUFSIZE)
+			item_len = 0;
+
+		if (sizeof(sh) + item_len + *sk_offset >
+		    BTRFS_SEARCH_ARGS_BUFSIZE) {
+			ret = 1;
+			goto overflow;
+		}
+
+		sh.objectid = key->objectid;
+		sh.offset = key->offset;
+		sh.type = key->type;
+		sh.len = item_len;
+		sh.transid = found_transid;
+
+		/* copy search result header */
+		memcpy(buf + *sk_offset, &sh, sizeof(sh));
+		*sk_offset += sizeof(sh);
+
+		if (item_len) {
+			char *p = buf + *sk_offset;
+			/* copy the item */
+			read_extent_buffer(leaf, p,
+					   item_off, item_len);
+			*sk_offset += item_len;
+		}
+		(*num_found)++;
+
+		if (*num_found >= sk->nr_items)
+			break;
+	}
+advance_key:
+	ret = 0;
+	if (key->offset < (u64)-1 && key->offset < sk->max_offset)
+		key->offset++;
+	else if (key->type < (u8)-1 && key->type < sk->max_type) {
+		key->offset = 0;
+		key->type++;
+	} else if (key->objectid < (u64)-1 && key->objectid < sk->max_objectid) {
+		key->offset = 0;
+		key->type = 0;
+		key->objectid++;
+	} else
+		ret = 1;
+overflow:
+	return ret;
+}
+
+static noinline int search_ioctl(struct inode *inode,
+				 struct btrfs_ioctl_search_args *args)
+{
+	struct btrfs_root *root;
+	struct btrfs_key key;
+	struct btrfs_key max_key;
+	struct btrfs_path *path;
+	struct btrfs_ioctl_search_key *sk = &args->key;
+	struct btrfs_fs_info *info = BTRFS_I(inode)->root->fs_info;
+	int ret;
+	int num_found = 0;
+	unsigned long sk_offset = 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	if (sk->tree_id == 0) {
+		/* search the root of the inode that was passed */
+		root = BTRFS_I(inode)->root;
+	} else {
+		key.objectid = sk->tree_id;
+		key.type = BTRFS_ROOT_ITEM_KEY;
+		key.offset = (u64)-1;
+		root = btrfs_read_fs_root_no_name(info, &key);
+		if (IS_ERR(root)) {
+			printk(KERN_ERR "could not find root %llu\n",
+			       sk->tree_id);
+			btrfs_free_path(path);
+			return -ENOENT;
+		}
+	}
+
+	key.objectid = sk->min_objectid;
+	key.type = sk->min_type;
+	key.offset = sk->min_offset;
+
+	max_key.objectid = sk->max_objectid;
+	max_key.type = sk->max_type;
+	max_key.offset = sk->max_offset;
+
+	path->keep_locks = 1;
+
+	while(1) {
+		ret = btrfs_search_forward(root, &key, &max_key, path,
+					   sk->min_transid);
+		if (ret != 0) {
+			if (ret > 0)
+				ret = 0;
+			goto err;
+		}
+		ret = copy_to_sk(root, path, &key, sk, args->buf,
+				 &sk_offset, &num_found);
+		btrfs_release_path(path);
+		if (ret || num_found >= sk->nr_items)
+			break;
+
+	}
+	ret = 0;
+err:
+	sk->nr_items = num_found;
+	btrfs_free_path(path);
+	return ret;
+}
+
+static noinline int btrfs_ioctl_tree_search(struct file *file,
+					   void __user *argp)
+{
+	 struct btrfs_ioctl_search_args *args;
+	 struct inode *inode;
+	 int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	args = memdup_user(argp, sizeof(*args));
+	if (IS_ERR(args))
+		return PTR_ERR(args);
+
+	inode = file_inode(file);
+	ret = search_ioctl(inode, args);
+	if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
+		ret = -EFAULT;
+	kfree(args);
+	return ret;
+}
+
+/*
+ * Search INODE_REFs to identify path name of 'dirid' directory
+ * in a 'tree_id' tree. and sets path name to 'name'.
+ */
+static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
+				u64 tree_id, u64 dirid, char *name)
+{
+	struct btrfs_root *root;
+	struct btrfs_key key;
+	char *ptr;
+	int ret = -1;
+	int slot;
+	int len;
+	int total_len = 0;
+	struct btrfs_inode_ref *iref;
+	struct extent_buffer *l;
+	struct btrfs_path *path;
+
+	if (dirid == BTRFS_FIRST_FREE_OBJECTID) {
+		name[0]='\0';
+		return 0;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ptr = &name[BTRFS_INO_LOOKUP_PATH_MAX];
+
+	key.objectid = tree_id;
+	key.type = BTRFS_ROOT_ITEM_KEY;
+	key.offset = (u64)-1;
+	root = btrfs_read_fs_root_no_name(info, &key);
+	if (IS_ERR(root)) {
+		printk(KERN_ERR "could not find root %llu\n", tree_id);
+		ret = -ENOENT;
+		goto out;
+	}
+
+	key.objectid = dirid;
+	key.type = BTRFS_INODE_REF_KEY;
+	key.offset = (u64)-1;
+
+	while(1) {
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		l = path->nodes[0];
+		slot = path->slots[0];
+		if (ret > 0 && slot > 0)
+			slot--;
+		btrfs_item_key_to_cpu(l, &key, slot);
+
+		if (ret > 0 && (key.objectid != dirid ||
+				key.type != BTRFS_INODE_REF_KEY)) {
+			ret = -ENOENT;
+			goto out;
+		}
+
+		iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);
+		len = btrfs_inode_ref_name_len(l, iref);
+		ptr -= len + 1;
+		total_len += len + 1;
+		if (ptr < name)
+			goto out;
+
+		*(ptr + len) = '/';
+		read_extent_buffer(l, ptr,(unsigned long)(iref + 1), len);
+
+		if (key.offset == BTRFS_FIRST_FREE_OBJECTID)
+			break;
+
+		btrfs_release_path(path);
+		key.objectid = key.offset;
+		key.offset = (u64)-1;
+		dirid = key.objectid;
+	}
+	if (ptr < name)
+		goto out;
+	memmove(name, ptr, total_len);
+	name[total_len]='\0';
+	ret = 0;
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static noinline int btrfs_ioctl_ino_lookup(struct file *file,
+					   void __user *argp)
+{
+	 struct btrfs_ioctl_ino_lookup_args *args;
+	 struct inode *inode;
+	 int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	args = memdup_user(argp, sizeof(*args));
+	if (IS_ERR(args))
+		return PTR_ERR(args);
+
+	inode = file_inode(file);
+
+	if (args->treeid == 0)
+		args->treeid = BTRFS_I(inode)->root->root_key.objectid;
+
+	ret = btrfs_search_path_in_tree(BTRFS_I(inode)->root->fs_info,
+					args->treeid, args->objectid,
+					args->name);
+
+	if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
+		ret = -EFAULT;
+
+	kfree(args);
+	return ret;
+}
+
+static noinline int btrfs_ioctl_snap_destroy(struct file *file,
+					     void __user *arg)
+{
+	struct dentry *parent = fdentry(file);
+	struct dentry *dentry;
+	struct inode *dir = parent->d_inode;
+	struct inode *inode;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_root *dest = NULL;
+	struct btrfs_ioctl_vol_args *vol_args;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_block_rsv block_rsv;
+	u64 qgroup_reserved;
+	int namelen;
+	int ret;
+	int err = 0;
+
+	vol_args = memdup_user(arg, sizeof(*vol_args));
+	if (IS_ERR(vol_args))
+		return PTR_ERR(vol_args);
+
+	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+	namelen = strlen(vol_args->name);
+	if (strchr(vol_args->name, '/') ||
+	    strncmp(vol_args->name, "..", namelen) == 0) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	err = mnt_want_write_file(file);
+	if (err)
+		goto out;
+
+	err = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
+	if (err == -EINTR)
+		goto out_drop_write;
+	dentry = lookup_one_len(vol_args->name, parent, namelen);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto out_unlock_dir;
+	}
+
+	if (!dentry->d_inode) {
+		err = -ENOENT;
+		goto out_dput;
+	}
+
+	inode = dentry->d_inode;
+	dest = BTRFS_I(inode)->root;
+	if (!capable(CAP_SYS_ADMIN)){
+		/*
+		 * Regular user.  Only allow this with a special mount
+		 * option, when the user has write+exec access to the
+		 * subvol root, and when rmdir(2) would have been
+		 * allowed.
+		 *
+		 * Note that this is _not_ check that the subvol is
+		 * empty or doesn't contain data that we wouldn't
+		 * otherwise be able to delete.
+		 *
+		 * Users who want to delete empty subvols should try
+		 * rmdir(2).
+		 */
+		err = -EPERM;
+		if (!btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
+			goto out_dput;
+
+		/*
+		 * Do not allow deletion if the parent dir is the same
+		 * as the dir to be deleted.  That means the ioctl
+		 * must be called on the dentry referencing the root
+		 * of the subvol, not a random directory contained
+		 * within it.
+		 */
+		err = -EINVAL;
+		if (root == dest)
+			goto out_dput;
+
+		err = inode_permission(inode, MAY_WRITE | MAY_EXEC);
+		if (err)
+			goto out_dput;
+	}
+
+	/* check if subvolume may be deleted by a user */
+	err = btrfs_may_delete(dir, dentry, 1);
+	if (err)
+		goto out_dput;
+
+	if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) {
+		err = -EINVAL;
+		goto out_dput;
+	}
+
+	mutex_lock(&inode->i_mutex);
+	err = d_invalidate(dentry);
+	if (err)
+		goto out_unlock;
+
+	down_write(&root->fs_info->subvol_sem);
+
+	err = may_destroy_subvol(dest);
+	if (err)
+		goto out_up_write;
+
+	btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
+	/*
+	 * One for dir inode, two for dir entries, two for root
+	 * ref/backref.
+	 */
+	err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
+					       5, &qgroup_reserved);
+	if (err)
+		goto out_up_write;
+
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		err = PTR_ERR(trans);
+		goto out_release;
+	}
+	trans->block_rsv = &block_rsv;
+	trans->bytes_reserved = block_rsv.size;
+
+	ret = btrfs_unlink_subvol(trans, root, dir,
+				dest->root_key.objectid,
+				dentry->d_name.name,
+				dentry->d_name.len);
+	if (ret) {
+		err = ret;
+		btrfs_abort_transaction(trans, root, ret);
+		goto out_end_trans;
+	}
+
+	btrfs_record_root_in_trans(trans, dest);
+
+	memset(&dest->root_item.drop_progress, 0,
+		sizeof(dest->root_item.drop_progress));
+	dest->root_item.drop_level = 0;
+	btrfs_set_root_refs(&dest->root_item, 0);
+
+	if (!xchg(&dest->orphan_item_inserted, 1)) {
+		ret = btrfs_insert_orphan_item(trans,
+					root->fs_info->tree_root,
+					dest->root_key.objectid);
+		if (ret) {
+			btrfs_abort_transaction(trans, root, ret);
+			err = ret;
+			goto out_end_trans;
+		}
+	}
+out_end_trans:
+	trans->block_rsv = NULL;
+	trans->bytes_reserved = 0;
+	ret = btrfs_end_transaction(trans, root);
+	if (ret && !err)
+		err = ret;
+	inode->i_flags |= S_DEAD;
+out_release:
+	btrfs_subvolume_release_metadata(root, &block_rsv, qgroup_reserved);
+out_up_write:
+	up_write(&root->fs_info->subvol_sem);
+out_unlock:
+	mutex_unlock(&inode->i_mutex);
+	if (!err) {
+		shrink_dcache_sb(root->fs_info->sb);
+		btrfs_invalidate_inodes(dest);
+		d_delete(dentry);
+
+		/* the last ref */
+		if (dest->cache_inode) {
+			iput(dest->cache_inode);
+			dest->cache_inode = NULL;
+		}
+	}
+out_dput:
+	dput(dentry);
+out_unlock_dir:
+	mutex_unlock(&dir->i_mutex);
+out_drop_write:
+	mnt_drop_write_file(file);
+out:
+	kfree(vol_args);
+	return err;
+}
+
+static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_ioctl_defrag_range_args *range;
+	int ret;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	if (btrfs_root_readonly(root)) {
+		ret = -EROFS;
+		goto out;
+	}
+
+	switch (inode->i_mode & S_IFMT) {
+	case S_IFDIR:
+		if (!capable(CAP_SYS_ADMIN)) {
+			ret = -EPERM;
+			goto out;
+		}
+		ret = btrfs_defrag_root(root);
+		if (ret)
+			goto out;
+		ret = btrfs_defrag_root(root->fs_info->extent_root);
+		break;
+	case S_IFREG:
+		if (!(file->f_mode & FMODE_WRITE)) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		range = kzalloc(sizeof(*range), GFP_KERNEL);
+		if (!range) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		if (argp) {
+			if (copy_from_user(range, argp,
+					   sizeof(*range))) {
+				ret = -EFAULT;
+				kfree(range);
+				goto out;
+			}
+			/* compression requires us to start the IO */
+			if ((range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
+				range->flags |= BTRFS_DEFRAG_RANGE_START_IO;
+				range->extent_thresh = (u32)-1;
+			}
+		} else {
+			/* the rest are all set to zero by kzalloc */
+			range->len = (u64)-1;
+		}
+		ret = btrfs_defrag_file(file_inode(file), file,
+					range, 0, 0);
+		if (ret > 0)
+			ret = 0;
+		kfree(range);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+out:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
+{
+	struct btrfs_ioctl_vol_args *vol_args;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+			1)) {
+		pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+		return -EINVAL;
+	}
+
+	mutex_lock(&root->fs_info->volume_mutex);
+	vol_args = memdup_user(arg, sizeof(*vol_args));
+	if (IS_ERR(vol_args)) {
+		ret = PTR_ERR(vol_args);
+		goto out;
+	}
+
+	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+	ret = btrfs_init_new_device(root, vol_args->name);
+
+	kfree(vol_args);
+out:
+	mutex_unlock(&root->fs_info->volume_mutex);
+	atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
+	return ret;
+}
+
+static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_ioctl_vol_args *vol_args;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
+			1)) {
+		pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+		mnt_drop_write_file(file);
+		return -EINVAL;
+	}
+
+	mutex_lock(&root->fs_info->volume_mutex);
+	vol_args = memdup_user(arg, sizeof(*vol_args));
+	if (IS_ERR(vol_args)) {
+		ret = PTR_ERR(vol_args);
+		goto out;
+	}
+
+	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+	ret = btrfs_rm_device(root, vol_args->name);
+
+	kfree(vol_args);
+out:
+	mutex_unlock(&root->fs_info->volume_mutex);
+	atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_fs_info(struct btrfs_root *root, void __user *arg)
+{
+	struct btrfs_ioctl_fs_info_args *fi_args;
+	struct btrfs_device *device;
+	struct btrfs_device *next;
+	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+	int ret = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	fi_args = kzalloc(sizeof(*fi_args), GFP_KERNEL);
+	if (!fi_args)
+		return -ENOMEM;
+
+	fi_args->num_devices = fs_devices->num_devices;
+	memcpy(&fi_args->fsid, root->fs_info->fsid, sizeof(fi_args->fsid));
+
+	mutex_lock(&fs_devices->device_list_mutex);
+	list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
+		if (device->devid > fi_args->max_id)
+			fi_args->max_id = device->devid;
+	}
+	mutex_unlock(&fs_devices->device_list_mutex);
+
+	if (copy_to_user(arg, fi_args, sizeof(*fi_args)))
+		ret = -EFAULT;
+
+	kfree(fi_args);
+	return ret;
+}
+
+static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
+{
+	struct btrfs_ioctl_dev_info_args *di_args;
+	struct btrfs_device *dev;
+	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+	int ret = 0;
+	char *s_uuid = NULL;
+	char empty_uuid[BTRFS_UUID_SIZE] = {0};
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	di_args = memdup_user(arg, sizeof(*di_args));
+	if (IS_ERR(di_args))
+		return PTR_ERR(di_args);
+
+	if (memcmp(empty_uuid, di_args->uuid, BTRFS_UUID_SIZE) != 0)
+		s_uuid = di_args->uuid;
+
+	mutex_lock(&fs_devices->device_list_mutex);
+	dev = btrfs_find_device(root->fs_info, di_args->devid, s_uuid, NULL);
+
+	if (!dev) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	di_args->devid = dev->devid;
+	di_args->bytes_used = dev->bytes_used;
+	di_args->total_bytes = dev->total_bytes;
+	memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
+	if (dev->name) {
+		struct rcu_string *name;
+
+		rcu_read_lock();
+		name = rcu_dereference(dev->name);
+		strncpy(di_args->path, name->str, sizeof(di_args->path));
+		rcu_read_unlock();
+		di_args->path[sizeof(di_args->path) - 1] = 0;
+	} else {
+		di_args->path[0] = '\0';
+	}
+
+out:
+	mutex_unlock(&fs_devices->device_list_mutex);
+	if (ret == 0 && copy_to_user(arg, di_args, sizeof(*di_args)))
+		ret = -EFAULT;
+
+	kfree(di_args);
+	return ret;
+}
+
+static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
+				       u64 off, u64 olen, u64 destoff)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct fd src_file;
+	struct inode *src;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	char *buf;
+	struct btrfs_key key;
+	u32 nritems;
+	int slot;
+	int ret;
+	u64 len = olen;
+	u64 bs = root->fs_info->sb->s_blocksize;
+
+	/*
+	 * TODO:
+	 * - split compressed inline extents.  annoying: we need to
+	 *   decompress into destination's address_space (the file offset
+	 *   may change, so source mapping won't do), then recompress (or
+	 *   otherwise reinsert) a subrange.
+	 * - allow ranges within the same file to be cloned (provided
+	 *   they don't overlap)?
+	 */
+
+	/* the destination must be opened for writing */
+	if (!(file->f_mode & FMODE_WRITE) || (file->f_flags & O_APPEND))
+		return -EINVAL;
+
+	if (btrfs_root_readonly(root))
+		return -EROFS;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	src_file = fdget(srcfd);
+	if (!src_file.file) {
+		ret = -EBADF;
+		goto out_drop_write;
+	}
+
+	ret = -EXDEV;
+	if (src_file.file->f_path.mnt != file->f_path.mnt)
+		goto out_fput;
+
+	src = file_inode(src_file.file);
+
+	ret = -EINVAL;
+	if (src == inode)
+		goto out_fput;
+
+	/* the src must be open for reading */
+	if (!(src_file.file->f_mode & FMODE_READ))
+		goto out_fput;
+
+	/* don't make the dst file partly checksummed */
+	if ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) !=
+	    (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM))
+		goto out_fput;
+
+	ret = -EISDIR;
+	if (S_ISDIR(src->i_mode) || S_ISDIR(inode->i_mode))
+		goto out_fput;
+
+	ret = -EXDEV;
+	if (src->i_sb != inode->i_sb)
+		goto out_fput;
+
+	ret = -ENOMEM;
+	buf = vmalloc(btrfs_level_size(root, 0));
+	if (!buf)
+		goto out_fput;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		vfree(buf);
+		goto out_fput;
+	}
+	path->reada = 2;
+
+	if (inode < src) {
+		mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
+		mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD);
+	} else {
+		mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT);
+		mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+	}
+
+	/* determine range to clone */
+	ret = -EINVAL;
+	if (off + len > src->i_size || off + len < off)
+		goto out_unlock;
+	if (len == 0)
+		olen = len = src->i_size - off;
+	/* if we extend to eof, continue to block boundary */
+	if (off + len == src->i_size)
+		len = ALIGN(src->i_size, bs) - off;
+
+	/* verify the end result is block aligned */
+	if (!IS_ALIGNED(off, bs) || !IS_ALIGNED(off + len, bs) ||
+	    !IS_ALIGNED(destoff, bs))
+		goto out_unlock;
+
+	if (destoff > inode->i_size) {
+		ret = btrfs_cont_expand(inode, inode->i_size, destoff);
+		if (ret)
+			goto out_unlock;
+	}
+
+	/* truncate page cache pages from target inode range */
+	truncate_inode_pages_range(&inode->i_data, destoff,
+				   PAGE_CACHE_ALIGN(destoff + len) - 1);
+
+	/* do any pending delalloc/csum calc on src, one way or
+	   another, and lock file content */
+	while (1) {
+		struct btrfs_ordered_extent *ordered;
+		lock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);
+		ordered = btrfs_lookup_first_ordered_extent(src, off + len - 1);
+		if (!ordered &&
+		    !test_range_bit(&BTRFS_I(src)->io_tree, off, off + len - 1,
+				    EXTENT_DELALLOC, 0, NULL))
+			break;
+		unlock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);
+		if (ordered)
+			btrfs_put_ordered_extent(ordered);
+		btrfs_wait_ordered_range(src, off, len);
+	}
+
+	/* clone data */
+	key.objectid = btrfs_ino(src);
+	key.type = BTRFS_EXTENT_DATA_KEY;
+	key.offset = 0;
+
+	while (1) {
+		/*
+		 * note the key will change type as we walk through the
+		 * tree.
+		 */
+		ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path,
+				0, 0);
+		if (ret < 0)
+			goto out;
+
+		nritems = btrfs_header_nritems(path->nodes[0]);
+		if (path->slots[0] >= nritems) {
+			ret = btrfs_next_leaf(BTRFS_I(src)->root, path);
+			if (ret < 0)
+				goto out;
+			if (ret > 0)
+				break;
+			nritems = btrfs_header_nritems(path->nodes[0]);
+		}
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
+		    key.objectid != btrfs_ino(src))
+			break;
+
+		if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
+			struct btrfs_file_extent_item *extent;
+			int type;
+			u32 size;
+			struct btrfs_key new_key;
+			u64 disko = 0, diskl = 0;
+			u64 datao = 0, datal = 0;
+			u8 comp;
+			u64 endoff;
+
+			size = btrfs_item_size_nr(leaf, slot);
+			read_extent_buffer(leaf, buf,
+					   btrfs_item_ptr_offset(leaf, slot),
+					   size);
+
+			extent = btrfs_item_ptr(leaf, slot,
+						struct btrfs_file_extent_item);
+			comp = btrfs_file_extent_compression(leaf, extent);
+			type = btrfs_file_extent_type(leaf, extent);
+			if (type == BTRFS_FILE_EXTENT_REG ||
+			    type == BTRFS_FILE_EXTENT_PREALLOC) {
+				disko = btrfs_file_extent_disk_bytenr(leaf,
+								      extent);
+				diskl = btrfs_file_extent_disk_num_bytes(leaf,
+								 extent);
+				datao = btrfs_file_extent_offset(leaf, extent);
+				datal = btrfs_file_extent_num_bytes(leaf,
+								    extent);
+			} else if (type == BTRFS_FILE_EXTENT_INLINE) {
+				/* take upper bound, may be compressed */
+				datal = btrfs_file_extent_ram_bytes(leaf,
+								    extent);
+			}
+			btrfs_release_path(path);
+
+			if (key.offset + datal <= off ||
+			    key.offset >= off + len - 1)
+				goto next;
+
+			memcpy(&new_key, &key, sizeof(new_key));
+			new_key.objectid = btrfs_ino(inode);
+			if (off <= key.offset)
+				new_key.offset = key.offset + destoff - off;
+			else
+				new_key.offset = destoff;
+
+			/*
+			 * 1 - adjusting old extent (we may have to split it)
+			 * 1 - add new extent
+			 * 1 - inode update
+			 */
+			trans = btrfs_start_transaction(root, 3);
+			if (IS_ERR(trans)) {
+				ret = PTR_ERR(trans);
+				goto out;
+			}
+
+			if (type == BTRFS_FILE_EXTENT_REG ||
+			    type == BTRFS_FILE_EXTENT_PREALLOC) {
+				/*
+				 *    a  | --- range to clone ---|  b
+				 * | ------------- extent ------------- |
+				 */
+
+				/* substract range b */
+				if (key.offset + datal > off + len)
+					datal = off + len - key.offset;
+
+				/* substract range a */
+				if (off > key.offset) {
+					datao += off - key.offset;
+					datal -= off - key.offset;
+				}
+
+				ret = btrfs_drop_extents(trans, root, inode,
+							 new_key.offset,
+							 new_key.offset + datal,
+							 1);
+				if (ret) {
+					btrfs_abort_transaction(trans, root,
+								ret);
+					btrfs_end_transaction(trans, root);
+					goto out;
+				}
+
+				ret = btrfs_insert_empty_item(trans, root, path,
+							      &new_key, size);
+				if (ret) {
+					btrfs_abort_transaction(trans, root,
+								ret);
+					btrfs_end_transaction(trans, root);
+					goto out;
+				}
+
+				leaf = path->nodes[0];
+				slot = path->slots[0];
+				write_extent_buffer(leaf, buf,
+					    btrfs_item_ptr_offset(leaf, slot),
+					    size);
+
+				extent = btrfs_item_ptr(leaf, slot,
+						struct btrfs_file_extent_item);
+
+				/* disko == 0 means it's a hole */
+				if (!disko)
+					datao = 0;
+
+				btrfs_set_file_extent_offset(leaf, extent,
+							     datao);
+				btrfs_set_file_extent_num_bytes(leaf, extent,
+								datal);
+				if (disko) {
+					inode_add_bytes(inode, datal);
+					ret = btrfs_inc_extent_ref(trans, root,
+							disko, diskl, 0,
+							root->root_key.objectid,
+							btrfs_ino(inode),
+							new_key.offset - datao,
+							0);
+					if (ret) {
+						btrfs_abort_transaction(trans,
+									root,
+									ret);
+						btrfs_end_transaction(trans,
+								      root);
+						goto out;
+
+					}
+				}
+			} else if (type == BTRFS_FILE_EXTENT_INLINE) {
+				u64 skip = 0;
+				u64 trim = 0;
+				if (off > key.offset) {
+					skip = off - key.offset;
+					new_key.offset += skip;
+				}
+
+				if (key.offset + datal > off + len)
+					trim = key.offset + datal - (off + len);
+
+				if (comp && (skip || trim)) {
+					ret = -EINVAL;
+					btrfs_end_transaction(trans, root);
+					goto out;
+				}
+				size -= skip + trim;
+				datal -= skip + trim;
+
+				ret = btrfs_drop_extents(trans, root, inode,
+							 new_key.offset,
+							 new_key.offset + datal,
+							 1);
+				if (ret) {
+					btrfs_abort_transaction(trans, root,
+								ret);
+					btrfs_end_transaction(trans, root);
+					goto out;
+				}
+
+				ret = btrfs_insert_empty_item(trans, root, path,
+							      &new_key, size);
+				if (ret) {
+					btrfs_abort_transaction(trans, root,
+								ret);
+					btrfs_end_transaction(trans, root);
+					goto out;
+				}
+
+				if (skip) {
+					u32 start =
+					  btrfs_file_extent_calc_inline_size(0);
+					memmove(buf+start, buf+start+skip,
+						datal);
+				}
+
+				leaf = path->nodes[0];
+				slot = path->slots[0];
+				write_extent_buffer(leaf, buf,
+					    btrfs_item_ptr_offset(leaf, slot),
+					    size);
+				inode_add_bytes(inode, datal);
+			}
+
+			btrfs_mark_buffer_dirty(leaf);
+			btrfs_release_path(path);
+
+			inode_inc_iversion(inode);
+			inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+
+			/*
+			 * we round up to the block size at eof when
+			 * determining which extents to clone above,
+			 * but shouldn't round up the file size
+			 */
+			endoff = new_key.offset + datal;
+			if (endoff > destoff+olen)
+				endoff = destoff+olen;
+			if (endoff > inode->i_size)
+				btrfs_i_size_write(inode, endoff);
+
+			ret = btrfs_update_inode(trans, root, inode);
+			if (ret) {
+				btrfs_abort_transaction(trans, root, ret);
+				btrfs_end_transaction(trans, root);
+				goto out;
+			}
+			ret = btrfs_end_transaction(trans, root);
+		}
+next:
+		btrfs_release_path(path);
+		key.offset++;
+	}
+	ret = 0;
+out:
+	btrfs_release_path(path);
+	unlock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);
+out_unlock:
+	mutex_unlock(&src->i_mutex);
+	mutex_unlock(&inode->i_mutex);
+	vfree(buf);
+	btrfs_free_path(path);
+out_fput:
+	fdput(src_file);
+out_drop_write:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_clone_range(struct file *file, void __user *argp)
+{
+	struct btrfs_ioctl_clone_range_args args;
+
+	if (copy_from_user(&args, argp, sizeof(args)))
+		return -EFAULT;
+	return btrfs_ioctl_clone(file, args.src_fd, args.src_offset,
+				 args.src_length, args.dest_offset);
+}
+
+/*
+ * there are many ways the trans_start and trans_end ioctls can lead
+ * to deadlocks.  They should only be used by applications that
+ * basically own the machine, and have a very in depth understanding
+ * of all the possible deadlocks and enospc problems.
+ */
+static long btrfs_ioctl_trans_start(struct file *file)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	ret = -EPERM;
+	if (!capable(CAP_SYS_ADMIN))
+		goto out;
+
+	ret = -EINPROGRESS;
+	if (file->private_data)
+		goto out;
+
+	ret = -EROFS;
+	if (btrfs_root_readonly(root))
+		goto out;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		goto out;
+
+	atomic_inc(&root->fs_info->open_ioctl_trans);
+
+	ret = -ENOMEM;
+	trans = btrfs_start_ioctl_transaction(root);
+	if (IS_ERR(trans))
+		goto out_drop;
+
+	file->private_data = trans;
+	return 0;
+
+out_drop:
+	atomic_dec(&root->fs_info->open_ioctl_trans);
+	mnt_drop_write_file(file);
+out:
+	return ret;
+}
+
+static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_root *new_root;
+	struct btrfs_dir_item *di;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_path *path;
+	struct btrfs_key location;
+	struct btrfs_disk_key disk_key;
+	u64 objectid = 0;
+	u64 dir_id;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	if (copy_from_user(&objectid, argp, sizeof(objectid))) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	if (!objectid)
+		objectid = root->root_key.objectid;
+
+	location.objectid = objectid;
+	location.type = BTRFS_ROOT_ITEM_KEY;
+	location.offset = (u64)-1;
+
+	new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
+	if (IS_ERR(new_root)) {
+		ret = PTR_ERR(new_root);
+		goto out;
+	}
+
+	if (btrfs_root_refs(&new_root->root_item) == 0) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	path->leave_spinning = 1;
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans)) {
+		btrfs_free_path(path);
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	dir_id = btrfs_super_root_dir(root->fs_info->super_copy);
+	di = btrfs_lookup_dir_item(trans, root->fs_info->tree_root, path,
+				   dir_id, "default", 7, 1);
+	if (IS_ERR_OR_NULL(di)) {
+		btrfs_free_path(path);
+		btrfs_end_transaction(trans, root);
+		printk(KERN_ERR "Umm, you don't have the default dir item, "
+		       "this isn't going to work\n");
+		ret = -ENOENT;
+		goto out;
+	}
+
+	btrfs_cpu_key_to_disk(&disk_key, &new_root->root_key);
+	btrfs_set_dir_item_key(path->nodes[0], di, &disk_key);
+	btrfs_mark_buffer_dirty(path->nodes[0]);
+	btrfs_free_path(path);
+
+	btrfs_set_fs_incompat(root->fs_info, DEFAULT_SUBVOL);
+	btrfs_end_transaction(trans, root);
+out:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+void btrfs_get_block_group_info(struct list_head *groups_list,
+				struct btrfs_ioctl_space_info *space)
+{
+	struct btrfs_block_group_cache *block_group;
+
+	space->total_bytes = 0;
+	space->used_bytes = 0;
+	space->flags = 0;
+	list_for_each_entry(block_group, groups_list, list) {
+		space->flags = block_group->flags;
+		space->total_bytes += block_group->key.offset;
+		space->used_bytes +=
+			btrfs_block_group_used(&block_group->item);
+	}
+}
+
+static long btrfs_ioctl_space_info(struct btrfs_root *root, void __user *arg)
+{
+	struct btrfs_ioctl_space_args space_args;
+	struct btrfs_ioctl_space_info space;
+	struct btrfs_ioctl_space_info *dest;
+	struct btrfs_ioctl_space_info *dest_orig;
+	struct btrfs_ioctl_space_info __user *user_dest;
+	struct btrfs_space_info *info;
+	u64 types[] = {BTRFS_BLOCK_GROUP_DATA,
+		       BTRFS_BLOCK_GROUP_SYSTEM,
+		       BTRFS_BLOCK_GROUP_METADATA,
+		       BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA};
+	int num_types = 4;
+	int alloc_size;
+	int ret = 0;
+	u64 slot_count = 0;
+	int i, c;
+
+	if (copy_from_user(&space_args,
+			   (struct btrfs_ioctl_space_args __user *)arg,
+			   sizeof(space_args)))
+		return -EFAULT;
+
+	for (i = 0; i < num_types; i++) {
+		struct btrfs_space_info *tmp;
+
+		info = NULL;
+		rcu_read_lock();
+		list_for_each_entry_rcu(tmp, &root->fs_info->space_info,
+					list) {
+			if (tmp->flags == types[i]) {
+				info = tmp;
+				break;
+			}
+		}
+		rcu_read_unlock();
+
+		if (!info)
+			continue;
+
+		down_read(&info->groups_sem);
+		for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
+			if (!list_empty(&info->block_groups[c]))
+				slot_count++;
+		}
+		up_read(&info->groups_sem);
+	}
+
+	/* space_slots == 0 means they are asking for a count */
+	if (space_args.space_slots == 0) {
+		space_args.total_spaces = slot_count;
+		goto out;
+	}
+
+	slot_count = min_t(u64, space_args.space_slots, slot_count);
+
+	alloc_size = sizeof(*dest) * slot_count;
+
+	/* we generally have at most 6 or so space infos, one for each raid
+	 * level.  So, a whole page should be more than enough for everyone
+	 */
+	if (alloc_size > PAGE_CACHE_SIZE)
+		return -ENOMEM;
+
+	space_args.total_spaces = 0;
+	dest = kmalloc(alloc_size, GFP_NOFS);
+	if (!dest)
+		return -ENOMEM;
+	dest_orig = dest;
+
+	/* now we have a buffer to copy into */
+	for (i = 0; i < num_types; i++) {
+		struct btrfs_space_info *tmp;
+
+		if (!slot_count)
+			break;
+
+		info = NULL;
+		rcu_read_lock();
+		list_for_each_entry_rcu(tmp, &root->fs_info->space_info,
+					list) {
+			if (tmp->flags == types[i]) {
+				info = tmp;
+				break;
+			}
+		}
+		rcu_read_unlock();
+
+		if (!info)
+			continue;
+		down_read(&info->groups_sem);
+		for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
+			if (!list_empty(&info->block_groups[c])) {
+				btrfs_get_block_group_info(
+					&info->block_groups[c], &space);
+				memcpy(dest, &space, sizeof(space));
+				dest++;
+				space_args.total_spaces++;
+				slot_count--;
+			}
+			if (!slot_count)
+				break;
+		}
+		up_read(&info->groups_sem);
+	}
+
+	user_dest = (struct btrfs_ioctl_space_info __user *)
+		(arg + sizeof(struct btrfs_ioctl_space_args));
+
+	if (copy_to_user(user_dest, dest_orig, alloc_size))
+		ret = -EFAULT;
+
+	kfree(dest_orig);
+out:
+	if (ret == 0 && copy_to_user(arg, &space_args, sizeof(space_args)))
+		ret = -EFAULT;
+
+	return ret;
+}
+
+/*
+ * there are many ways the trans_start and trans_end ioctls can lead
+ * to deadlocks.  They should only be used by applications that
+ * basically own the machine, and have a very in depth understanding
+ * of all the possible deadlocks and enospc problems.
+ */
+long btrfs_ioctl_trans_end(struct file *file)
+{
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_trans_handle *trans;
+
+	trans = file->private_data;
+	if (!trans)
+		return -EINVAL;
+	file->private_data = NULL;
+
+	btrfs_end_transaction(trans, root);
+
+	atomic_dec(&root->fs_info->open_ioctl_trans);
+
+	mnt_drop_write_file(file);
+	return 0;
+}
+
+static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
+					    void __user *argp)
+{
+	struct btrfs_trans_handle *trans;
+	u64 transid;
+	int ret;
+
+	trans = btrfs_attach_transaction_barrier(root);
+	if (IS_ERR(trans)) {
+		if (PTR_ERR(trans) != -ENOENT)
+			return PTR_ERR(trans);
+
+		/* No running transaction, don't bother */
+		transid = root->fs_info->last_trans_committed;
+		goto out;
+	}
+	transid = trans->transid;
+	ret = btrfs_commit_transaction_async(trans, root, 0);
+	if (ret) {
+		btrfs_end_transaction(trans, root);
+		return ret;
+	}
+out:
+	if (argp)
+		if (copy_to_user(argp, &transid, sizeof(transid)))
+			return -EFAULT;
+	return 0;
+}
+
+static noinline long btrfs_ioctl_wait_sync(struct btrfs_root *root,
+					   void __user *argp)
+{
+	u64 transid;
+
+	if (argp) {
+		if (copy_from_user(&transid, argp, sizeof(transid)))
+			return -EFAULT;
+	} else {
+		transid = 0;  /* current trans */
+	}
+	return btrfs_wait_for_commit(root, transid);
+}
+
+static long btrfs_ioctl_scrub(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_ioctl_scrub_args *sa;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa))
+		return PTR_ERR(sa);
+
+	if (!(sa->flags & BTRFS_SCRUB_READONLY)) {
+		ret = mnt_want_write_file(file);
+		if (ret)
+			goto out;
+	}
+
+	ret = btrfs_scrub_dev(root->fs_info, sa->devid, sa->start, sa->end,
+			      &sa->progress, sa->flags & BTRFS_SCRUB_READONLY,
+			      0);
+
+	if (copy_to_user(arg, sa, sizeof(*sa)))
+		ret = -EFAULT;
+
+	if (!(sa->flags & BTRFS_SCRUB_READONLY))
+		mnt_drop_write_file(file);
+out:
+	kfree(sa);
+	return ret;
+}
+
+static long btrfs_ioctl_scrub_cancel(struct btrfs_root *root, void __user *arg)
+{
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	return btrfs_scrub_cancel(root->fs_info);
+}
+
+static long btrfs_ioctl_scrub_progress(struct btrfs_root *root,
+				       void __user *arg)
+{
+	struct btrfs_ioctl_scrub_args *sa;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa))
+		return PTR_ERR(sa);
+
+	ret = btrfs_scrub_progress(root, sa->devid, &sa->progress);
+
+	if (copy_to_user(arg, sa, sizeof(*sa)))
+		ret = -EFAULT;
+
+	kfree(sa);
+	return ret;
+}
+
+static long btrfs_ioctl_get_dev_stats(struct btrfs_root *root,
+				      void __user *arg)
+{
+	struct btrfs_ioctl_get_dev_stats *sa;
+	int ret;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa))
+		return PTR_ERR(sa);
+
+	if ((sa->flags & BTRFS_DEV_STATS_RESET) && !capable(CAP_SYS_ADMIN)) {
+		kfree(sa);
+		return -EPERM;
+	}
+
+	ret = btrfs_get_dev_stats(root, sa);
+
+	if (copy_to_user(arg, sa, sizeof(*sa)))
+		ret = -EFAULT;
+
+	kfree(sa);
+	return ret;
+}
+
+static long btrfs_ioctl_dev_replace(struct btrfs_root *root, void __user *arg)
+{
+	struct btrfs_ioctl_dev_replace_args *p;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	p = memdup_user(arg, sizeof(*p));
+	if (IS_ERR(p))
+		return PTR_ERR(p);
+
+	switch (p->cmd) {
+	case BTRFS_IOCTL_DEV_REPLACE_CMD_START:
+		if (root->fs_info->sb->s_flags & MS_RDONLY)
+			return -EROFS;
+
+		if (atomic_xchg(
+			&root->fs_info->mutually_exclusive_operation_running,
+			1)) {
+			pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+			ret = -EINPROGRESS;
+		} else {
+			ret = btrfs_dev_replace_start(root, p);
+			atomic_set(
+			 &root->fs_info->mutually_exclusive_operation_running,
+			 0);
+		}
+		break;
+	case BTRFS_IOCTL_DEV_REPLACE_CMD_STATUS:
+		btrfs_dev_replace_status(root->fs_info, p);
+		ret = 0;
+		break;
+	case BTRFS_IOCTL_DEV_REPLACE_CMD_CANCEL:
+		ret = btrfs_dev_replace_cancel(root->fs_info, p);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	if (copy_to_user(arg, p, sizeof(*p)))
+		ret = -EFAULT;
+
+	kfree(p);
+	return ret;
+}
+
+static long btrfs_ioctl_ino_to_path(struct btrfs_root *root, void __user *arg)
+{
+	int ret = 0;
+	int i;
+	u64 rel_ptr;
+	int size;
+	struct btrfs_ioctl_ino_path_args *ipa = NULL;
+	struct inode_fs_paths *ipath = NULL;
+	struct btrfs_path *path;
+
+	if (!capable(CAP_DAC_READ_SEARCH))
+		return -EPERM;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ipa = memdup_user(arg, sizeof(*ipa));
+	if (IS_ERR(ipa)) {
+		ret = PTR_ERR(ipa);
+		ipa = NULL;
+		goto out;
+	}
+
+	size = min_t(u32, ipa->size, 4096);
+	ipath = init_ipath(size, root, path);
+	if (IS_ERR(ipath)) {
+		ret = PTR_ERR(ipath);
+		ipath = NULL;
+		goto out;
+	}
+
+	ret = paths_from_inode(ipa->inum, ipath);
+	if (ret < 0)
+		goto out;
+
+	for (i = 0; i < ipath->fspath->elem_cnt; ++i) {
+		rel_ptr = ipath->fspath->val[i] -
+			  (u64)(unsigned long)ipath->fspath->val;
+		ipath->fspath->val[i] = rel_ptr;
+	}
+
+	ret = copy_to_user((void *)(unsigned long)ipa->fspath,
+			   (void *)(unsigned long)ipath->fspath, size);
+	if (ret) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+out:
+	btrfs_free_path(path);
+	free_ipath(ipath);
+	kfree(ipa);
+
+	return ret;
+}
+
+static int build_ino_list(u64 inum, u64 offset, u64 root, void *ctx)
+{
+	struct btrfs_data_container *inodes = ctx;
+	const size_t c = 3 * sizeof(u64);
+
+	if (inodes->bytes_left >= c) {
+		inodes->bytes_left -= c;
+		inodes->val[inodes->elem_cnt] = inum;
+		inodes->val[inodes->elem_cnt + 1] = offset;
+		inodes->val[inodes->elem_cnt + 2] = root;
+		inodes->elem_cnt += 3;
+	} else {
+		inodes->bytes_missing += c - inodes->bytes_left;
+		inodes->bytes_left = 0;
+		inodes->elem_missed += 3;
+	}
+
+	return 0;
+}
+
+static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
+					void __user *arg)
+{
+	int ret = 0;
+	int size;
+	struct btrfs_ioctl_logical_ino_args *loi;
+	struct btrfs_data_container *inodes = NULL;
+	struct btrfs_path *path = NULL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	loi = memdup_user(arg, sizeof(*loi));
+	if (IS_ERR(loi)) {
+		ret = PTR_ERR(loi);
+		loi = NULL;
+		goto out;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	size = min_t(u32, loi->size, 64 * 1024);
+	inodes = init_data_container(size);
+	if (IS_ERR(inodes)) {
+		ret = PTR_ERR(inodes);
+		inodes = NULL;
+		goto out;
+	}
+
+	ret = iterate_inodes_from_logical(loi->logical, root->fs_info, path,
+					  build_ino_list, inodes);
+	if (ret == -EINVAL)
+		ret = -ENOENT;
+	if (ret < 0)
+		goto out;
+
+	ret = copy_to_user((void *)(unsigned long)loi->inodes,
+			   (void *)(unsigned long)inodes, size);
+	if (ret)
+		ret = -EFAULT;
+
+out:
+	btrfs_free_path(path);
+	vfree(inodes);
+	kfree(loi);
+
+	return ret;
+}
+
+void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
+			       struct btrfs_ioctl_balance_args *bargs)
+{
+	struct btrfs_balance_control *bctl = fs_info->balance_ctl;
+
+	bargs->flags = bctl->flags;
+
+	if (atomic_read(&fs_info->balance_running))
+		bargs->state |= BTRFS_BALANCE_STATE_RUNNING;
+	if (atomic_read(&fs_info->balance_pause_req))
+		bargs->state |= BTRFS_BALANCE_STATE_PAUSE_REQ;
+	if (atomic_read(&fs_info->balance_cancel_req))
+		bargs->state |= BTRFS_BALANCE_STATE_CANCEL_REQ;
+
+	memcpy(&bargs->data, &bctl->data, sizeof(bargs->data));
+	memcpy(&bargs->meta, &bctl->meta, sizeof(bargs->meta));
+	memcpy(&bargs->sys, &bctl->sys, sizeof(bargs->sys));
+
+	if (lock) {
+		spin_lock(&fs_info->balance_lock);
+		memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
+		spin_unlock(&fs_info->balance_lock);
+	} else {
+		memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
+	}
+}
+
+static long btrfs_ioctl_balance(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_ioctl_balance_args *bargs;
+	struct btrfs_balance_control *bctl;
+	bool need_unlock; /* for mut. excl. ops lock */
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+again:
+	if (!atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {
+		mutex_lock(&fs_info->volume_mutex);
+		mutex_lock(&fs_info->balance_mutex);
+		need_unlock = true;
+		goto locked;
+	}
+
+	/*
+	 * mut. excl. ops lock is locked.  Three possibilites:
+	 *   (1) some other op is running
+	 *   (2) balance is running
+	 *   (3) balance is paused -- special case (think resume)
+	 */
+	mutex_lock(&fs_info->balance_mutex);
+	if (fs_info->balance_ctl) {
+		/* this is either (2) or (3) */
+		if (!atomic_read(&fs_info->balance_running)) {
+			mutex_unlock(&fs_info->balance_mutex);
+			if (!mutex_trylock(&fs_info->volume_mutex))
+				goto again;
+			mutex_lock(&fs_info->balance_mutex);
+
+			if (fs_info->balance_ctl &&
+			    !atomic_read(&fs_info->balance_running)) {
+				/* this is (3) */
+				need_unlock = false;
+				goto locked;
+			}
+
+			mutex_unlock(&fs_info->balance_mutex);
+			mutex_unlock(&fs_info->volume_mutex);
+			goto again;
+		} else {
+			/* this is (2) */
+			mutex_unlock(&fs_info->balance_mutex);
+			ret = -EINPROGRESS;
+			goto out;
+		}
+	} else {
+		/* this is (1) */
+		mutex_unlock(&fs_info->balance_mutex);
+		pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+locked:
+	BUG_ON(!atomic_read(&fs_info->mutually_exclusive_operation_running));
+
+	if (arg) {
+		bargs = memdup_user(arg, sizeof(*bargs));
+		if (IS_ERR(bargs)) {
+			ret = PTR_ERR(bargs);
+			goto out_unlock;
+		}
+
+		if (bargs->flags & BTRFS_BALANCE_RESUME) {
+			if (!fs_info->balance_ctl) {
+				ret = -ENOTCONN;
+				goto out_bargs;
+			}
+
+			bctl = fs_info->balance_ctl;
+			spin_lock(&fs_info->balance_lock);
+			bctl->flags |= BTRFS_BALANCE_RESUME;
+			spin_unlock(&fs_info->balance_lock);
+
+			goto do_balance;
+		}
+	} else {
+		bargs = NULL;
+	}
+
+	if (fs_info->balance_ctl) {
+		ret = -EINPROGRESS;
+		goto out_bargs;
+	}
+
+	bctl = kzalloc(sizeof(*bctl), GFP_NOFS);
+	if (!bctl) {
+		ret = -ENOMEM;
+		goto out_bargs;
+	}
+
+	bctl->fs_info = fs_info;
+	if (arg) {
+		memcpy(&bctl->data, &bargs->data, sizeof(bctl->data));
+		memcpy(&bctl->meta, &bargs->meta, sizeof(bctl->meta));
+		memcpy(&bctl->sys, &bargs->sys, sizeof(bctl->sys));
+
+		bctl->flags = bargs->flags;
+	} else {
+		/* balance everything - no filters */
+		bctl->flags |= BTRFS_BALANCE_TYPE_MASK;
+	}
+
+do_balance:
+	/*
+	 * Ownership of bctl and mutually_exclusive_operation_running
+	 * goes to to btrfs_balance.  bctl is freed in __cancel_balance,
+	 * or, if restriper was paused all the way until unmount, in
+	 * free_fs_info.  mutually_exclusive_operation_running is
+	 * cleared in __cancel_balance.
+	 */
+	need_unlock = false;
+
+	ret = btrfs_balance(bctl, bargs);
+
+	if (arg) {
+		if (copy_to_user(arg, bargs, sizeof(*bargs)))
+			ret = -EFAULT;
+	}
+
+out_bargs:
+	kfree(bargs);
+out_unlock:
+	mutex_unlock(&fs_info->balance_mutex);
+	mutex_unlock(&fs_info->volume_mutex);
+	if (need_unlock)
+		atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+out:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_balance_ctl(struct btrfs_root *root, int cmd)
+{
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	switch (cmd) {
+	case BTRFS_BALANCE_CTL_PAUSE:
+		return btrfs_pause_balance(root->fs_info);
+	case BTRFS_BALANCE_CTL_CANCEL:
+		return btrfs_cancel_balance(root->fs_info);
+	}
+
+	return -EINVAL;
+}
+
+static long btrfs_ioctl_balance_progress(struct btrfs_root *root,
+					 void __user *arg)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_ioctl_balance_args *bargs;
+	int ret = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	mutex_lock(&fs_info->balance_mutex);
+	if (!fs_info->balance_ctl) {
+		ret = -ENOTCONN;
+		goto out;
+	}
+
+	bargs = kzalloc(sizeof(*bargs), GFP_NOFS);
+	if (!bargs) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	update_ioctl_balance_args(fs_info, 1, bargs);
+
+	if (copy_to_user(arg, bargs, sizeof(*bargs)))
+		ret = -EFAULT;
+
+	kfree(bargs);
+out:
+	mutex_unlock(&fs_info->balance_mutex);
+	return ret;
+}
+
+static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_ioctl_quota_ctl_args *sa;
+	struct btrfs_trans_handle *trans = NULL;
+	int ret;
+	int err;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa)) {
+		ret = PTR_ERR(sa);
+		goto drop_write;
+	}
+
+	down_write(&root->fs_info->subvol_sem);
+	trans = btrfs_start_transaction(root->fs_info->tree_root, 2);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	switch (sa->cmd) {
+	case BTRFS_QUOTA_CTL_ENABLE:
+		ret = btrfs_quota_enable(trans, root->fs_info);
+		break;
+	case BTRFS_QUOTA_CTL_DISABLE:
+		ret = btrfs_quota_disable(trans, root->fs_info);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	if (copy_to_user(arg, sa, sizeof(*sa)))
+		ret = -EFAULT;
+
+	err = btrfs_commit_transaction(trans, root->fs_info->tree_root);
+	if (err && !ret)
+		ret = err;
+out:
+	kfree(sa);
+	up_write(&root->fs_info->subvol_sem);
+drop_write:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_ioctl_qgroup_assign_args *sa;
+	struct btrfs_trans_handle *trans;
+	int ret;
+	int err;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa)) {
+		ret = PTR_ERR(sa);
+		goto drop_write;
+	}
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	/* FIXME: check if the IDs really exist */
+	if (sa->assign) {
+		ret = btrfs_add_qgroup_relation(trans, root->fs_info,
+						sa->src, sa->dst);
+	} else {
+		ret = btrfs_del_qgroup_relation(trans, root->fs_info,
+						sa->src, sa->dst);
+	}
+
+	err = btrfs_end_transaction(trans, root);
+	if (err && !ret)
+		ret = err;
+
+out:
+	kfree(sa);
+drop_write:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_ioctl_qgroup_create_args *sa;
+	struct btrfs_trans_handle *trans;
+	int ret;
+	int err;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa)) {
+		ret = PTR_ERR(sa);
+		goto drop_write;
+	}
+
+	if (!sa->qgroupid) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	/* FIXME: check if the IDs really exist */
+	if (sa->create) {
+		ret = btrfs_create_qgroup(trans, root->fs_info, sa->qgroupid,
+					  NULL);
+	} else {
+		ret = btrfs_remove_qgroup(trans, root->fs_info, sa->qgroupid);
+	}
+
+	err = btrfs_end_transaction(trans, root);
+	if (err && !ret)
+		ret = err;
+
+out:
+	kfree(sa);
+drop_write:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	struct btrfs_ioctl_qgroup_limit_args *sa;
+	struct btrfs_trans_handle *trans;
+	int ret;
+	int err;
+	u64 qgroupid;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa)) {
+		ret = PTR_ERR(sa);
+		goto drop_write;
+	}
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
+
+	qgroupid = sa->qgroupid;
+	if (!qgroupid) {
+		/* take the current subvol as qgroup */
+		qgroupid = root->root_key.objectid;
+	}
+
+	/* FIXME: check if the IDs really exist */
+	ret = btrfs_limit_qgroup(trans, root->fs_info, qgroupid, &sa->lim);
+
+	err = btrfs_end_transaction(trans, root);
+	if (err && !ret)
+		ret = err;
+
+out:
+	kfree(sa);
+drop_write:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_quota_rescan(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+	struct btrfs_ioctl_quota_rescan_args *qsa;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	qsa = memdup_user(arg, sizeof(*qsa));
+	if (IS_ERR(qsa)) {
+		ret = PTR_ERR(qsa);
+		goto drop_write;
+	}
+
+	if (qsa->flags) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = btrfs_qgroup_rescan(root->fs_info);
+
+out:
+	kfree(qsa);
+drop_write:
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static long btrfs_ioctl_quota_rescan_status(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+	struct btrfs_ioctl_quota_rescan_args *qsa;
+	int ret = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	qsa = kzalloc(sizeof(*qsa), GFP_NOFS);
+	if (!qsa)
+		return -ENOMEM;
+
+	if (root->fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
+		qsa->flags = 1;
+		qsa->progress = root->fs_info->qgroup_rescan_progress.objectid;
+	}
+
+	if (copy_to_user(arg, qsa, sizeof(*qsa)))
+		ret = -EFAULT;
+
+	kfree(qsa);
+	return ret;
+}
+
+static long btrfs_ioctl_set_received_subvol(struct file *file,
+					    void __user *arg)
+{
+	struct btrfs_ioctl_received_subvol_args *sa = NULL;
+	struct inode *inode = file_inode(file);
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_root_item *root_item = &root->root_item;
+	struct btrfs_trans_handle *trans;
+	struct timespec ct = CURRENT_TIME;
+	int ret = 0;
+
+	ret = mnt_want_write_file(file);
+	if (ret < 0)
+		return ret;
+
+	down_write(&root->fs_info->subvol_sem);
+
+	if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (btrfs_root_readonly(root)) {
+		ret = -EROFS;
+		goto out;
+	}
+
+	if (!inode_owner_or_capable(inode)) {
+		ret = -EACCES;
+		goto out;
+	}
+
+	sa = memdup_user(arg, sizeof(*sa));
+	if (IS_ERR(sa)) {
+		ret = PTR_ERR(sa);
+		sa = NULL;
+		goto out;
+	}
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		trans = NULL;
+		goto out;
+	}
+
+	sa->rtransid = trans->transid;
+	sa->rtime.sec = ct.tv_sec;
+	sa->rtime.nsec = ct.tv_nsec;
+
+	memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
+	btrfs_set_root_stransid(root_item, sa->stransid);
+	btrfs_set_root_rtransid(root_item, sa->rtransid);
+	root_item->stime.sec = cpu_to_le64(sa->stime.sec);
+	root_item->stime.nsec = cpu_to_le32(sa->stime.nsec);
+	root_item->rtime.sec = cpu_to_le64(sa->rtime.sec);
+	root_item->rtime.nsec = cpu_to_le32(sa->rtime.nsec);
+
+	ret = btrfs_update_root(trans, root->fs_info->tree_root,
+				&root->root_key, &root->root_item);
+	if (ret < 0) {
+		btrfs_end_transaction(trans, root);
+		trans = NULL;
+		goto out;
+	} else {
+		ret = btrfs_commit_transaction(trans, root);
+		if (ret < 0)
+			goto out;
+	}
+
+	ret = copy_to_user(arg, sa, sizeof(*sa));
+	if (ret)
+		ret = -EFAULT;
+
+out:
+	kfree(sa);
+	up_write(&root->fs_info->subvol_sem);
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+static int btrfs_ioctl_get_fslabel(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+	const char *label = root->fs_info->super_copy->label;
+	size_t len = strnlen(label, BTRFS_LABEL_SIZE);
+	int ret;
+
+	if (len == BTRFS_LABEL_SIZE) {
+		pr_warn("btrfs: label is too long, return the first %zu bytes\n",
+			--len);
+	}
+
+	mutex_lock(&root->fs_info->volume_mutex);
+	ret = copy_to_user(arg, label, len);
+	mutex_unlock(&root->fs_info->volume_mutex);
+
+	return ret ? -EFAULT : 0;
+}
+
+static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+	struct btrfs_super_block *super_block = root->fs_info->super_copy;
+	struct btrfs_trans_handle *trans;
+	char label[BTRFS_LABEL_SIZE];
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (copy_from_user(label, arg, sizeof(label)))
+		return -EFAULT;
+
+	if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE) {
+		pr_err("btrfs: unable to set label with more than %d bytes\n",
+		       BTRFS_LABEL_SIZE - 1);
+		return -EINVAL;
+	}
+
+	ret = mnt_want_write_file(file);
+	if (ret)
+		return ret;
+
+	mutex_lock(&root->fs_info->volume_mutex);
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out_unlock;
+	}
+
+	strcpy(super_block->label, label);
+	ret = btrfs_end_transaction(trans, root);
+
+out_unlock:
+	mutex_unlock(&root->fs_info->volume_mutex);
+	mnt_drop_write_file(file);
+	return ret;
+}
+
+long btrfs_ioctl(struct file *file, unsigned int
+		cmd, unsigned long arg)
+{
+	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
+	void __user *argp = (void __user *)arg;
+
+	switch (cmd) {
+	case FS_IOC_GETFLAGS:
+		return btrfs_ioctl_getflags(file, argp);
+	case FS_IOC_SETFLAGS:
+		return btrfs_ioctl_setflags(file, argp);
+	case FS_IOC_GETVERSION:
+		return btrfs_ioctl_getversion(file, argp);
+	case FITRIM:
+		return btrfs_ioctl_fitrim(file, argp);
+	case BTRFS_IOC_SNAP_CREATE:
+		return btrfs_ioctl_snap_create(file, argp, 0);
+	case BTRFS_IOC_SNAP_CREATE_V2:
+		return btrfs_ioctl_snap_create_v2(file, argp, 0);
+	case BTRFS_IOC_SUBVOL_CREATE:
+		return btrfs_ioctl_snap_create(file, argp, 1);
+	case BTRFS_IOC_SUBVOL_CREATE_V2:
+		return btrfs_ioctl_snap_create_v2(file, argp, 1);
+	case BTRFS_IOC_SNAP_DESTROY:
+		return btrfs_ioctl_snap_destroy(file, argp);
+	case BTRFS_IOC_SUBVOL_GETFLAGS:
+		return btrfs_ioctl_subvol_getflags(file, argp);
+	case BTRFS_IOC_SUBVOL_SETFLAGS:
+		return btrfs_ioctl_subvol_setflags(file, argp);
+	case BTRFS_IOC_DEFAULT_SUBVOL:
+		return btrfs_ioctl_default_subvol(file, argp);
+	case BTRFS_IOC_DEFRAG:
+		return btrfs_ioctl_defrag(file, NULL);
+	case BTRFS_IOC_DEFRAG_RANGE:
+		return btrfs_ioctl_defrag(file, argp);
+	case BTRFS_IOC_RESIZE:
+		return btrfs_ioctl_resize(file, argp);
+	case BTRFS_IOC_ADD_DEV:
+		return btrfs_ioctl_add_dev(root, argp);
+	case BTRFS_IOC_RM_DEV:
+		return btrfs_ioctl_rm_dev(file, argp);
+	case BTRFS_IOC_FS_INFO:
+		return btrfs_ioctl_fs_info(root, argp);
+	case BTRFS_IOC_DEV_INFO:
+		return btrfs_ioctl_dev_info(root, argp);
+	case BTRFS_IOC_BALANCE:
+		return btrfs_ioctl_balance(file, NULL);
+	case BTRFS_IOC_CLONE:
+		return btrfs_ioctl_clone(file, arg, 0, 0, 0);
+	case BTRFS_IOC_CLONE_RANGE:
+		return btrfs_ioctl_clone_range(file, argp);
+	case BTRFS_IOC_TRANS_START:
+		return btrfs_ioctl_trans_start(file);
+	case BTRFS_IOC_TRANS_END:
+		return btrfs_ioctl_trans_end(file);
+	case BTRFS_IOC_TREE_SEARCH:
+		return btrfs_ioctl_tree_search(file, argp);
+	case BTRFS_IOC_INO_LOOKUP:
+		return btrfs_ioctl_ino_lookup(file, argp);
+	case BTRFS_IOC_INO_PATHS:
+		return btrfs_ioctl_ino_to_path(root, argp);
+	case BTRFS_IOC_LOGICAL_INO:
+		return btrfs_ioctl_logical_to_ino(root, argp);
+	case BTRFS_IOC_SPACE_INFO:
+		return btrfs_ioctl_space_info(root, argp);
+	case BTRFS_IOC_SYNC:
+		btrfs_sync_fs(file->f_dentry->d_sb, 1);
+		return 0;
+	case BTRFS_IOC_START_SYNC:
+		return btrfs_ioctl_start_sync(root, argp);
+	case BTRFS_IOC_WAIT_SYNC:
+		return btrfs_ioctl_wait_sync(root, argp);
+	case BTRFS_IOC_SCRUB:
+		return btrfs_ioctl_scrub(file, argp);
+	case BTRFS_IOC_SCRUB_CANCEL:
+		return btrfs_ioctl_scrub_cancel(root, argp);
+	case BTRFS_IOC_SCRUB_PROGRESS:
+		return btrfs_ioctl_scrub_progress(root, argp);
+	case BTRFS_IOC_BALANCE_V2:
+		return btrfs_ioctl_balance(file, argp);
+	case BTRFS_IOC_BALANCE_CTL:
+		return btrfs_ioctl_balance_ctl(root, arg);
+	case BTRFS_IOC_BALANCE_PROGRESS:
+		return btrfs_ioctl_balance_progress(root, argp);
+	case BTRFS_IOC_SET_RECEIVED_SUBVOL:
+		return btrfs_ioctl_set_received_subvol(file, argp);
+	case BTRFS_IOC_SEND:
+		return btrfs_ioctl_send(file, argp);
+	case BTRFS_IOC_GET_DEV_STATS:
+		return btrfs_ioctl_get_dev_stats(root, argp);
+	case BTRFS_IOC_QUOTA_CTL:
+		return btrfs_ioctl_quota_ctl(file, argp);
+	case BTRFS_IOC_QGROUP_ASSIGN:
+		return btrfs_ioctl_qgroup_assign(file, argp);
+	case BTRFS_IOC_QGROUP_CREATE:
+		return btrfs_ioctl_qgroup_create(file, argp);
+	case BTRFS_IOC_QGROUP_LIMIT:
+		return btrfs_ioctl_qgroup_limit(file, argp);
+	case BTRFS_IOC_QUOTA_RESCAN:
+		return btrfs_ioctl_quota_rescan(file, argp);
+	case BTRFS_IOC_QUOTA_RESCAN_STATUS:
+		return btrfs_ioctl_quota_rescan_status(file, argp);
+	case BTRFS_IOC_DEV_REPLACE:
+		return btrfs_ioctl_dev_replace(root, argp);
+	case BTRFS_IOC_GET_FSLABEL:
+		return btrfs_ioctl_get_fslabel(file, argp);
+	case BTRFS_IOC_SET_FSLABEL:
+		return btrfs_ioctl_set_fslabel(file, argp);
+	}
+
+	return -ENOTTY;
+}