/*
   * 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 "compat.h"

  #include "ctree.h"
  #include "disk-io.h"
  #include "transaction.h"
  #include "btrfs_inode.h"
  #include "ioctl.h"
  #include "print-tree.h"
  #include "volumes.h"

  #include "locking.h"

  #include "inode-map.h"

  #include "backref.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;

  	btrfs_update_iflags(inode);
  }
  
  static int btrfs_ioctl_getflags(struct file *file, void __user *arg)
  {
  	struct btrfs_inode *ip = BTRFS_I(file->f_path.dentry->d_inode);
  	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->f_path.dentry->d_inode;
  	struct btrfs_inode *ip = BTRFS_I(inode);
  	struct btrfs_root *root = ip->root;
  	struct btrfs_trans_handle *trans;
  	unsigned int flags, oldflags;
  	int ret;

  	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;
  
  	mutex_lock(&inode->i_mutex);
  
  	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;
  		}
  	}

  	ret = mnt_want_write_file(file);

  	if (ret)
  		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)
  		ip->flags |= BTRFS_INODE_NODATACOW;
  	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_join_transaction(root);

  	BUG_ON(IS_ERR(trans));

  	btrfs_update_iflags(inode);
  	inode->i_ctime = CURRENT_TIME;

  	ret = btrfs_update_inode(trans, root, inode);
  	BUG_ON(ret);

  	btrfs_end_transaction(trans, root);

  	mnt_drop_write_file(file);

  
  	ret = 0;

   out_unlock:
  	mutex_unlock(&inode->i_mutex);

  	return ret;

  }
  
  static int btrfs_ioctl_getversion(struct file *file, int __user *arg)
  {
  	struct inode *inode = file->f_path.dentry->d_inode;
  
  	return put_user(inode->i_generation, arg);
  }

  static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
  {
  	struct btrfs_root *root = fdentry(file)->d_sb->s_fs_info;
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	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(root->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)
  		return -EINVAL;

  	range.len = min(range.len, total_bytes - range.start);

  	range.minlen = max(range.minlen, minlen);
  	ret = btrfs_trim_fs(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 btrfs_root *root,
  				  struct dentry *dentry,

  				  char *name, int namelen,
  				  u64 *async_transid)

  {
  	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 *new_root;

  	struct dentry *parent = dentry->d_parent;

  	struct inode *dir;

  	int ret;
  	int err;
  	u64 objectid;
  	u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;

  	u64 index = 0;

  	ret = btrfs_find_free_objectid(root->fs_info->tree_root, &objectid);

  	if (ret)

  		return ret;

  
  	dir = parent->d_inode;

  	/*
  	 * 1 - inode item
  	 * 2 - refs
  	 * 1 - root item
  	 * 2 - dir items
  	 */

  	trans = btrfs_start_transaction(root, 6);

  	if (IS_ERR(trans))

  		return PTR_ERR(trans);

  	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);
  
  	inode_item = &root_item.inode;
  	memset(inode_item, 0, sizeof(*inode_item));
  	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);

  
  	memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
  	root_item.drop_level = 0;

  	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);
  	BUG_ON(IS_ERR(new_root));
  
  	btrfs_record_root_in_trans(trans, new_root);

  	ret = btrfs_create_subvol_root(trans, new_root, new_dirid);

  	/*
  	 * insert the directory item
  	 */

  	ret = btrfs_set_inode_index(dir, &index);
  	BUG_ON(ret);
  
  	ret = btrfs_insert_dir_item(trans, root,

  				    name, namelen, dir, &key,

  				    BTRFS_FT_DIR, index);

  	if (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);

  	d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));

  fail:

  	if (async_transid) {
  		*async_transid = trans->transid;
  		err = btrfs_commit_transaction_async(trans, root, 1);
  	} else {
  		err = btrfs_commit_transaction(trans, root);
  	}

  	if (err && !ret)
  		ret = err;

  	return ret;
  }

  static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,

  			   char *name, int namelen, u64 *async_transid,
  			   bool readonly)

  {

  	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);

  	pending_snapshot->dentry = dentry;

  	pending_snapshot->root = root;

  	pending_snapshot->readonly = readonly;

  
  	trans = btrfs_start_transaction(root->fs_info->extent_root, 5);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto fail;
  	}
  
  	ret = btrfs_snap_reserve_metadata(trans, pending_snapshot);
  	BUG_ON(ret);

  	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);
  	} else {
  		ret = btrfs_commit_transaction(trans,
  					       root->fs_info->extent_root);
  	}

  	BUG_ON(ret);

  
  	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:

  	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)
  {
  	uid_t fsuid = current_fsuid();
  
  	if (!(dir->i_mode & S_ISVTX))
  		return 0;
  	if (inode->i_uid == fsuid)
  		return 0;
  	if (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(victim, dir);
  
  	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 inode *dir  = parent->dentry->d_inode;

  	struct dentry *dentry;
  	int error;

  	mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);

  
  	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 = mnt_want_write(parent->mnt);
  	if (error)
  		goto out_dput;

  	error = btrfs_may_create(dir, dentry);

  	if (error)
  		goto out_drop_write;

  	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, dentry,

  					name, namelen, async_transid, readonly);

  	} else {

  		error = create_subvol(BTRFS_I(dir)->root, dentry,

  				      name, namelen, async_transid);

  	}

  	if (!error)
  		fsnotify_mkdir(dir, dentry);
  out_up_read:
  	up_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);

  out_drop_write:
  	mnt_drop_write(parent->mnt);
  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, 0, 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 int should_defrag_range(struct inode *inode, u64 start, u64 len,

  			       int thresh, u64 *last_len, u64 *skip,
  			       u64 *defrag_end)

  {
  	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;
  	int ret = 1;
  
  	/*

  	 * make sure that once we start defragging an extent, we keep on

  	 * defragging it
  	 */
  	if (start < *defrag_end)
  		return 1;
  
  	*skip = 0;
  
  	/*
  	 * 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, GFP_NOFS);
  		em = btrfs_get_extent(inode, NULL, 0, start, len, 0);
  		unlock_extent(io_tree, start, start + len - 1, GFP_NOFS);

  		if (IS_ERR(em))

  			return 0;
  	}
  
  	/* this will cover holes, and inline extents */
  	if (em->block_start >= EXTENT_MAP_LAST_BYTE)
  		ret = 0;
  
  	/*
  	 * we hit a real extent, if it is big don't bother defragging it again
  	 */

  	if ((*last_len == 0 || *last_len >= thresh) && em->len >= thresh)

  		ret = 0;
  
  	/*
  	 * 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;
  	int ret;
  	int i;
  	int i_done;

  	struct btrfs_ordered_extent *ordered;

  	struct extent_state *cached_state = NULL;

  	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);

  
  	if (isize == 0)
  		return 0;
  	file_end = (isize - 1) >> PAGE_CACHE_SHIFT;

  	mutex_lock(&inode->i_mutex);

  	ret = btrfs_delalloc_reserve_space(inode,
  					   num_pages << PAGE_CACHE_SHIFT);

  	mutex_unlock(&inode->i_mutex);

  	if (ret)
  		return ret;
  again:
  	ret = 0;
  	i_done = 0;
  
  	/* step one, lock all the pages */
  	for (i = 0; i < num_pages; i++) {
  		struct page *page;

  		page = find_or_create_page(inode->i_mapping,

  					    start_index + i, mask);

  		if (!page)
  			break;
  
  		if (!PageUptodate(page)) {
  			btrfs_readpage(NULL, page);
  			lock_page(page);
  			if (!PageUptodate(page)) {
  				unlock_page(page);
  				page_cache_release(page);
  				ret = -EIO;
  				break;
  			}
  		}
  		isize = i_size_read(inode);
  		file_end = (isize - 1) >> PAGE_CACHE_SHIFT;
  		if (!isize || page->index > file_end ||
  		    page->mapping != inode->i_mapping) {
  			/* whoops, we blew past eof, skip this page */
  			unlock_page(page);
  			page_cache_release(page);
  			break;
  		}
  		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,
  			 GFP_NOFS);
  	ordered = btrfs_lookup_first_ordered_extent(inode, page_end - 1);
  	if (ordered &&
  	    ordered->file_offset + ordered->len > page_start &&
  	    ordered->file_offset < page_end) {
  		btrfs_put_ordered_extent(ordered);
  		unlock_extent_cached(&BTRFS_I(inode)->io_tree,
  				     page_start, page_end - 1,
  				     &cached_state, GFP_NOFS);
  		for (i = 0; i < i_done; i++) {
  			unlock_page(pages[i]);
  			page_cache_release(pages[i]);
  		}
  		btrfs_wait_ordered_range(inode, page_start,
  					 page_end - page_start);
  		goto again;
  	}
  	if (ordered)
  		btrfs_put_ordered_extent(ordered);
  
  	clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start,
  			  page_end - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
  			  EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
  			  GFP_NOFS);
  
  	if (i_done != num_pages) {

  		spin_lock(&BTRFS_I(inode)->lock);
  		BTRFS_I(inode)->outstanding_extents++;
  		spin_unlock(&BTRFS_I(inode)->lock);

  		btrfs_delalloc_release_space(inode,
  				     (num_pages - i_done) << PAGE_CACHE_SHIFT);
  	}
  
  
  	btrfs_set_extent_delalloc(inode, page_start, page_end - 1,
  				  &cached_state);
  
  	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, num_pages << 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 btrfs_super_block *disk_super;

  	struct file_ra_state *ra = NULL;

  	unsigned long last_index;

  	u64 isize = i_size_read(inode);

  	u64 features;

  	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 (extent_thresh == 0)
  		extent_thresh = 256 * 1024;

  
  	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 (isize == 0)

  		return 0;

  	/*
  	 * 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;

  	/*
  	 * 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 (!newer_than &&
  		    !should_defrag_range(inode, (u64)i << PAGE_CACHE_SHIFT,

  					PAGE_CACHE_SIZE,

  					extent_thresh,

  					&last_len, &skip,

  					&defrag_end)) {
  			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;
  		}

  		ret = cluster_pages_for_defrag(inode, pages, i, cluster);

  		if (ret < 0)
  			goto out_ra;
  
  		defrag_count += ret;
  		balance_dirty_pages_ratelimited_nr(inode->i_mapping, ret);

  
  		if (newer_than) {
  			if (newer_off == (u64)-1)
  				break;
  
  			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);
  	}

  	disk_super = root->fs_info->super_copy;

  	features = btrfs_super_incompat_flags(disk_super);
  	if (range->compress_type == BTRFS_COMPRESS_LZO) {
  		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
  		btrfs_set_super_incompat_flags(disk_super, features);
  	}

  	ret = defrag_count;

  out_ra:
  	if (!file)
  		kfree(ra);
  	kfree(pages);

  	return ret;

  }

  static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
  					void __user *arg)

  {
  	u64 new_size;
  	u64 old_size;
  	u64 devid = 1;
  	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 (root->fs_info->sb->s_flags & MS_RDONLY)
  		return -EROFS;

  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;

  	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';

  	mutex_lock(&root->fs_info->volume_mutex);

  	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);

  		printk(KERN_INFO "btrfs: resizing devid %llu
  ",

  		       (unsigned long long)devid);

  	}

  	device = btrfs_find_device(root, devid, NULL, NULL);

  	if (!device) {

  		printk(KERN_INFO "btrfs: resizer unable to find device %llu
  ",

  		       (unsigned long long)devid);

  		ret = -EINVAL;
  		goto out_unlock;
  	}
  	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_unlock;
  		}
  	}
  
  	old_size = device->total_bytes;
  
  	if (mod < 0) {
  		if (new_size > old_size) {
  			ret = -EINVAL;
  			goto out_unlock;
  		}
  		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_unlock;
  	}
  	if (new_size > device->bdev->bd_inode->i_size) {
  		ret = -EFBIG;
  		goto out_unlock;
  	}
  
  	do_div(new_size, root->sectorsize);
  	new_size *= root->sectorsize;

  	printk(KERN_INFO "btrfs: new size for %s is %llu
  ",

  		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_unlock;
  		}

  		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);
  	}
  
  out_unlock:

  	mutex_unlock(&root->fs_info->volume_mutex);

  	kfree(vol_args);
  	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_root *root = BTRFS_I(fdentry(file)->d_inode)->root;

  	struct file *src_file;

  	int namelen;

  	int ret = 0;

  	if (root->fs_info->sb->s_flags & MS_RDONLY)
  		return -EROFS;

  	namelen = strlen(name);
  	if (strchr(name, '/')) {

  		ret = -EINVAL;
  		goto out;
  	}

  	if (subvol) {

  		ret = btrfs_mksubvol(&file->f_path, name, namelen,

  				     NULL, transid, readonly);

  	} else {

  		struct inode *src_inode;

  		src_file = fget(fd);

  		if (!src_file) {
  			ret = -EINVAL;
  			goto out;
  		}
  
  		src_inode = src_file->f_path.dentry->d_inode;
  		if (src_inode->i_sb != file->f_path.dentry->d_inode->i_sb) {

  			printk(KERN_INFO "btrfs: Snapshot src from "
  			       "another FS
  ");

  			ret = -EINVAL;
  			fput(src_file);
  			goto out;
  		}

  		ret = btrfs_mksubvol(&file->f_path, name, namelen,
  				     BTRFS_I(src_inode)->root,

  				     transid, readonly);

  		fput(src_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);

  	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;

  	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)) {
  		ret = -EOPNOTSUPP;

  		goto out;

  	}

  
  	if (vol_args->flags & BTRFS_SUBVOL_CREATE_ASYNC)
  		ptr = &transid;

  	if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
  		readonly = true;

  
  	ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,

  					      vol_args->fd, subvol,
  					      ptr, readonly);

  
  	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);
  	return ret;
  }

  static noinline int btrfs_ioctl_subvol_getflags(struct file *file,
  						void __user *arg)
  {
  	struct inode *inode = fdentry(file)->d_inode;
  	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 = fdentry(file)->d_inode;
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_trans_handle *trans;
  	u64 root_flags;
  	u64 flags;
  	int ret = 0;
  
  	if (root->fs_info->sb->s_flags & MS_RDONLY)
  		return -EROFS;

  	if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID)

  		return -EINVAL;
  
  	if (copy_from_user(&flags, arg, sizeof(flags)))
  		return -EFAULT;

  	if (flags & BTRFS_SUBVOL_CREATE_ASYNC)

  		return -EINVAL;
  
  	if (flags & ~BTRFS_SUBVOL_RDONLY)
  		return -EOPNOTSUPP;

  	if (!inode_owner_or_capable(inode))

  		return -EACCES;

  	down_write(&root->fs_info->subvol_sem);
  
  	/* nothing to do */
  	if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root))
  		goto out;
  
  	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:
  	up_write(&root->fs_info->subvol_sem);
  	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);
  
  		if (item_len > BTRFS_SEARCH_ARGS_BUFSIZE)
  			item_len = 0;
  
  		if (sizeof(sh) + item_len + *sk_offset >
  		    BTRFS_SEARCH_ARGS_BUFSIZE) {
  			ret = 1;
  			goto overflow;
  		}
  
  		btrfs_item_key_to_cpu(leaf, key, i);
  		if (!key_in_sk(key, sk))
  			continue;
  
  		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
  ",
  			       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, 0,
  					   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 = fdentry(file)->d_inode;
  	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
  ", 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 = fdentry(file)->d_inode;

  	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;
  	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;
  
  	mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
  	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 non-root 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;

  	trans = btrfs_start_transaction(root, 0);
  	if (IS_ERR(trans)) {
  		err = PTR_ERR(trans);

  		goto out_up_write;

  	}
  	trans->block_rsv = &root->fs_info->global_block_rsv;

  	ret = btrfs_unlink_subvol(trans, root, dir,
  				dest->root_key.objectid,
  				dentry->d_name.name,
  				dentry->d_name.len);
  	BUG_ON(ret);
  
  	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);
  		BUG_ON(ret);
  	}

  	ret = btrfs_end_transaction(trans, root);

  	BUG_ON(ret);
  	inode->i_flags |= S_DEAD;
  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);
  	}
  out_dput:
  	dput(dentry);
  out_unlock_dir:
  	mutex_unlock(&dir->i_mutex);

  	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 = fdentry(file)->d_inode;
  	struct btrfs_root *root = BTRFS_I(inode)->root;

  	struct btrfs_ioctl_defrag_range_args *range;

  	int ret;

  	if (btrfs_root_readonly(root))
  		return -EROFS;

  	ret = mnt_want_write_file(file);

  	if (ret)
  		return ret;

  
  	switch (inode->i_mode & S_IFMT) {
  	case S_IFDIR:

  		if (!capable(CAP_SYS_ADMIN)) {
  			ret = -EPERM;
  			goto out;
  		}

  		ret = btrfs_defrag_root(root, 0);
  		if (ret)
  			goto out;
  		ret = btrfs_defrag_root(root->fs_info->extent_root, 0);

  		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(fdentry(file)->d_inode, 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;

  	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_init_new_device(root, vol_args->name);

  	kfree(vol_args);
  	return ret;
  }

  static long btrfs_ioctl_rm_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 (root->fs_info->sb->s_flags & MS_RDONLY)
  		return -EROFS;

  	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_rm_device(root, vol_args->name);

  	kfree(vol_args);
  	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, di_args->devid, s_uuid, NULL);
  	mutex_unlock(&fs_devices->device_list_mutex);
  
  	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));
  	strncpy(di_args->path, dev->name, sizeof(di_args->path));
  
  out:
  	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 = fdentry(file)->d_inode;
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct file *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;
  	u64 hint_byte;

  	/*
  	 * 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 = fget(srcfd);

  	if (!src_file) {
  		ret = -EBADF;
  		goto out_drop_write;
  	}

  	src = src_file->f_dentry->d_inode;

  	ret = -EINVAL;
  	if (src == inode)
  		goto out_fput;

  	/* the src must be open for reading */
  	if (!(src_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 || BTRFS_I(src)->root != root)
  		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, GFP_NOFS);

  		ordered = btrfs_lookup_first_ordered_extent(src, off+len);
  		if (!ordered &&
  		    !test_range_bit(&BTRFS_I(src)->io_tree, off, off+len,
  				   EXTENT_DELALLOC, 0, NULL))

  			break;

  		unlock_extent(&BTRFS_I(src)->io_tree, off, off+len, GFP_NOFS);

  		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, 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(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)
  				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, inode,
  							 new_key.offset,
  							 new_key.offset + datal,
  							 &hint_byte, 1);
  				BUG_ON(ret);

  				ret = btrfs_insert_empty_item(trans, root, path,
  							      &new_key, size);

  				BUG_ON(ret);

  
  				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);

  					BUG_ON(ret);

  				}

  			} 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, inode,
  							 new_key.offset,
  							 new_key.offset + datal,
  							 &hint_byte, 1);
  				BUG_ON(ret);

  				ret = btrfs_insert_empty_item(trans, root, path,
  							      &new_key, size);

  				BUG_ON(ret);

  
  				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->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);
  			BUG_ON(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, GFP_NOFS);

  out_unlock:
  	mutex_unlock(&src->i_mutex);
  	mutex_unlock(&inode->i_mutex);

  	vfree(buf);
  	btrfs_free_path(path);

  out_fput:
  	fput(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 = fdentry(file)->d_inode;
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_trans_handle *trans;

  	int ret;