/*
   * 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 <linux/uaccess.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"

  #include "props.h"

  #include "sysfs.h"

  #include "qgroup.h"

  #include "tree-log.h"

  #include "compression.h"

  #ifdef CONFIG_64BIT
  /* If we have a 32-bit userspace and 64-bit kernel, then the UAPI
   * structures are incorrect, as the timespec structure from userspace
   * is 4 bytes too small. We define these alternatives here to teach
   * the kernel about the 32-bit struct packing.
   */
  struct btrfs_ioctl_timespec_32 {
  	__u64 sec;
  	__u32 nsec;
  } __attribute__ ((__packed__));
  
  struct btrfs_ioctl_received_subvol_args_32 {
  	char	uuid[BTRFS_UUID_SIZE];	/* in */
  	__u64	stransid;		/* in */
  	__u64	rtransid;		/* out */
  	struct btrfs_ioctl_timespec_32 stime; /* in */
  	struct btrfs_ioctl_timespec_32 rtime; /* out */
  	__u64	flags;			/* in */
  	__u64	reserved[16];		/* in */
  } __attribute__ ((__packed__));
  
  #define BTRFS_IOC_SET_RECEIVED_SUBVOL_32 _IOWR(BTRFS_IOCTL_MAGIC, 37, \
  				struct btrfs_ioctl_received_subvol_args_32)
  #endif

  static int btrfs_clone(struct inode *src, struct inode *inode,

  		       u64 off, u64 olen, u64 olen_aligned, u64 destoff,
  		       int no_time_update);

  /* 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_NOCOMPRESS)

  		iflags |= FS_NOCOMP_FL;

  	else if (flags & BTRFS_INODE_COMPRESS)
  		iflags |= FS_COMPR_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);

  	unsigned int new_fl = 0;

  
  	if (ip->flags & BTRFS_INODE_SYNC)

  		new_fl |= S_SYNC;

  	if (ip->flags & BTRFS_INODE_IMMUTABLE)

  		new_fl |= S_IMMUTABLE;

  	if (ip->flags & BTRFS_INODE_APPEND)

  		new_fl |= S_APPEND;

  	if (ip->flags & BTRFS_INODE_NOATIME)

  		new_fl |= S_NOATIME;

  	if (ip->flags & BTRFS_INODE_DIRSYNC)

  		new_fl |= S_DIRSYNC;
  
  	set_mask_bits(&inode->i_flags,
  		      S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC,
  		      new_fl);

  }
  
  /*
   * 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 (!inode_owner_or_capable(inode))
  		return -EPERM;

  	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;

  	ret = mnt_want_write_file(file);
  	if (ret)
  		return ret;

  	inode_lock(inode);

  	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 assumptions 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;

  
  		ret = btrfs_set_prop(inode, "btrfs.compression", NULL, 0, 0);
  		if (ret && ret != -ENODATA)
  			goto out_drop;

  	} else if (flags & FS_COMPR_FL) {

  		const char *comp;

  		ip->flags |= BTRFS_INODE_COMPRESS;
  		ip->flags &= ~BTRFS_INODE_NOCOMPRESS;

  
  		if (root->fs_info->compress_type == BTRFS_COMPRESS_LZO)
  			comp = "lzo";
  		else
  			comp = "zlib";
  		ret = btrfs_set_prop(inode, "btrfs.compression",
  				     comp, strlen(comp), 0);
  		if (ret)
  			goto out_drop;

  	} else {

  		ret = btrfs_set_prop(inode, "btrfs.compression", NULL, 0, 0);
  		if (ret && ret != -ENODATA)
  			goto out_drop;

  		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(inode);

  	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:

  	inode_unlock(inode);

  	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(file_inode(file)->i_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;
  }

  int btrfs_is_empty_uuid(u8 *uuid)
  {

  	int i;
  
  	for (i = 0; i < BTRFS_UUID_SIZE; i++) {
  		if (uuid[i])
  			return 0;
  	}
  	return 1;

  }

  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(dir);

  	struct inode *inode;

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

  	u64 index = 0;

  	u64 qgroup_reserved;

  	uuid_le new_uuid;

  	root_item = kzalloc(sizeof(*root_item), GFP_KERNEL);
  	if (!root_item)
  		return -ENOMEM;

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

  	if (ret)

  		goto fail_free;

  	/*
  	 * Don't create subvolume whose level is not zero. Or qgroup will be

  	 * screwed up since it assumes subvolume qgroup's level to be 0.

  	 */

  	if (btrfs_qgroup_level(objectid)) {
  		ret = -ENOSPC;
  		goto fail_free;
  	}

  	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,

  					       8, &qgroup_reserved, false);

  	if (ret)

  		goto fail_free;

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

  		btrfs_subvolume_release_metadata(root, &block_rsv,
  						 qgroup_reserved);

  		goto fail_free;

  	}
  	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_tree_block(trans, root, 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, btrfs_header_fsid(),

  			    BTRFS_FSID_SIZE);

  	write_extent_buffer(leaf, root->fs_info->chunk_tree_uuid,

  			    btrfs_header_chunk_tree_uuid(leaf),

  			    BTRFS_UUID_SIZE);

  	btrfs_mark_buffer_dirty(leaf);

  	inode_item = &root_item->inode;

  	btrfs_set_stack_inode_generation(inode_item, 1);
  	btrfs_set_stack_inode_size(inode_item, 3);
  	btrfs_set_stack_inode_nlink(inode_item, 1);

  	btrfs_set_stack_inode_nbytes(inode_item, root->nodesize);

  	btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);

  	btrfs_set_root_flags(root_item, 0);
  	btrfs_set_root_limit(root_item, 0);

  	btrfs_set_stack_inode_flags(inode_item, 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);
  	btrfs_set_stack_timespec_sec(&root_item->otime, cur_time.tv_sec);
  	btrfs_set_stack_timespec_nsec(&root_item->otime, 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;

  	key.type = 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)) {

  		ret = PTR_ERR(new_root);

  		btrfs_abort_transaction(trans, ret);

  		goto fail;
  	}

  
  	btrfs_record_root_in_trans(trans, new_root);

  	ret = btrfs_create_subvol_root(trans, new_root, root, new_dirid);

  	if (ret) {
  		/* We potentially lose an unused inode item here */

  		btrfs_abort_transaction(trans, ret);

  		goto fail;
  	}

  	mutex_lock(&new_root->objectid_mutex);
  	new_root->highest_objectid = new_dirid;
  	mutex_unlock(&new_root->objectid_mutex);

  	/*
  	 * insert the directory item
  	 */

  	ret = btrfs_set_inode_index(dir, &index);

  	if (ret) {

  		btrfs_abort_transaction(trans, ret);

  		goto fail;
  	}

  
  	ret = btrfs_insert_dir_item(trans, root,

  				    name, namelen, dir, &key,

  				    BTRFS_FT_DIR, index);

  	if (ret) {

  		btrfs_abort_transaction(trans, 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);

  	ret = btrfs_uuid_tree_add(trans, root->fs_info->uuid_root,

  				  root_item->uuid, BTRFS_UUID_KEY_SUBVOL,

  				  objectid);
  	if (ret)

  		btrfs_abort_transaction(trans, ret);

  fail:

  	kfree(root_item);

  	trans->block_rsv = NULL;
  	trans->bytes_reserved = 0;

  	btrfs_subvolume_release_metadata(root, &block_rsv, qgroup_reserved);

  	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) {
  		inode = btrfs_lookup_dentry(dir, dentry);

  		if (IS_ERR(inode))
  			return PTR_ERR(inode);

  		d_instantiate(dentry, inode);
  	}

  	return ret;

  
  fail_free:
  	kfree(root_item);
  	return ret;

  }

  static void btrfs_wait_for_no_snapshoting_writes(struct btrfs_root *root)

  {
  	s64 writers;
  	DEFINE_WAIT(wait);
  
  	do {
  		prepare_to_wait(&root->subv_writers->wait, &wait,
  				TASK_UNINTERRUPTIBLE);
  
  		writers = percpu_counter_sum(&root->subv_writers->counter);
  		if (writers)
  			schedule();
  
  		finish_wait(&root->subv_writers->wait, &wait);
  	} while (writers);
  }

  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 (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))

  		return -EINVAL;

  	pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_NOFS);
  	if (!pending_snapshot)
  		return -ENOMEM;

  	pending_snapshot->root_item = kzalloc(sizeof(struct btrfs_root_item),
  			GFP_NOFS);

  	pending_snapshot->path = btrfs_alloc_path();
  	if (!pending_snapshot->root_item || !pending_snapshot->path) {

  		ret = -ENOMEM;
  		goto free_pending;
  	}

  	atomic_inc(&root->will_be_snapshoted);

  	smp_mb__after_atomic();

  	btrfs_wait_for_no_snapshoting_writes(root);

  	ret = btrfs_start_delalloc_inodes(root, 0);
  	if (ret)

  		goto dec_and_free;

  	btrfs_wait_ordered_extents(root, -1, 0, (u64)-1);

  	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

  	 * 1 - UUID item

  	 */
  	ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,

  					&pending_snapshot->block_rsv, 8,

  					&pending_snapshot->qgroup_reserved,
  					false);

  	if (ret)

  		goto dec_and_free;

  	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(d_inode(dentry->d_parent), dentry);

  	if (IS_ERR(inode)) {
  		ret = PTR_ERR(inode);
  		goto fail;
  	}

  	d_instantiate(dentry, inode);
  	ret = 0;
  fail:

  	btrfs_subvolume_release_metadata(BTRFS_I(dir)->root,
  					 &pending_snapshot->block_rsv,
  					 pending_snapshot->qgroup_reserved);

  dec_and_free:

  	if (atomic_dec_and_test(&root->will_be_snapshoted))
  		wake_up_atomic_t(&root->will_be_snapshoted);

  free_pending:
  	kfree(pending_snapshot->root_item);

  	btrfs_free_path(pending_snapshot->path);

  	kfree(pending_snapshot);

  	return ret;
  }

  /*  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 anything 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 (d_really_is_negative(victim))

  		return -ENOENT;

  	BUG_ON(d_inode(victim->d_parent) != 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 (check_sticky(dir, d_inode(victim)) || IS_APPEND(d_inode(victim)) ||
  	    IS_IMMUTABLE(d_inode(victim)) || IS_SWAPFILE(d_inode(victim)))

  		return -EPERM;
  	if (isdir) {

  		if (!d_is_dir(victim))

  			return -ENOTDIR;
  		if (IS_ROOT(victim))
  			return -EBUSY;

  	} else if (d_is_dir(victim))

  		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 (d_really_is_positive(child))

  		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  = d_inode(parent->dentry);

  	struct dentry *dentry;
  	int error;

  	error = down_write_killable_nested(&dir->i_rwsem, 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 = 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:

  	inode_unlock(dir);

  	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, u32 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_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, u32 thresh)

  {
  	struct btrfs_path *path;
  	struct btrfs_key min_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;

  	while (1) {

  		ret = btrfs_search_forward(root, &min_key, path, newer_than);

  		if (ret != 0)
  			goto none;

  process_slot:

  		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;
  		}

  		path->slots[0]++;
  		if (path->slots[0] < btrfs_header_nritems(leaf)) {
  			btrfs_item_key_to_cpu(leaf, &min_key, path->slots[0]);
  			goto process_slot;
  		}

  		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_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) {

  		struct extent_state *cached = NULL;
  		u64 end = start + len - 1;

  		/* get the big lock and read metadata off disk */

  		lock_extent_bits(io_tree, start, end, &cached);

  		em = btrfs_get_extent(inode, NULL, 0, start, len, 0);

  		unlock_extent_cached(io_tree, start, end, &cached, GFP_NOFS);

  
  		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;
  	else if ((em->block_start + em->block_len == next->block_start) &&

  		 (em->block_len > SZ_128K && next->block_len > SZ_128K))

  		ret = false;
  
  	free_extent_map(next);

  	return ret;
  }

  static int should_defrag_range(struct inode *inode, u64 start, u32 thresh,

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

  {

  	struct extent_map *em;

  	int ret = 1;

  	bool next_mergeable = true;

  	bool prev_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;
  	}

  	if (!*defrag_end)
  		prev_mergeable = false;

  	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 && !prev_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,

  				    unsigned long 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_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,

  			start_index << PAGE_SHIFT,
  			page_cnt << PAGE_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_SIZE - 1;

  		while (1) {

  			lock_extent_bits(tree, page_start, page_end,

  					 &cached_state);

  			ordered = btrfs_lookup_ordered_extent(inode,
  							      page_start);

  			unlock_extent_cached(tree, page_start, page_end,
  					     &cached_state, GFP_NOFS);

  			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);

  				put_page(page);

  				goto again;
  			}

  		}

  		if (!PageUptodate(page)) {
  			btrfs_readpage(NULL, page);
  			lock_page(page);
  			if (!PageUptodate(page)) {
  				unlock_page(page);

  				put_page(page);

  				ret = -EIO;
  				break;
  			}
  		}

  		if (page->mapping != inode->i_mapping) {
  			unlock_page(page);

  			put_page(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_SIZE;

  
  	lock_extent_bits(&BTRFS_I(inode)->io_tree,

  			 page_start, page_end - 1, &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,

  				start_index << PAGE_SHIFT,
  				(page_cnt - i_done) << PAGE_SHIFT);

  	}

  	set_extent_defrag(&BTRFS_I(inode)->io_tree, 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]);

  		put_page(pages[i]);

  	}
  	return i_done;
  out:
  	for (i = 0; i < i_done; i++) {
  		unlock_page(pages[i]);

  		put_page(pages[i]);

  	}

  	btrfs_delalloc_release_space(inode,

  			start_index << PAGE_SHIFT,
  			page_cnt << PAGE_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;

  	u32 extent_thresh = range->extent_thresh;

  	unsigned long max_cluster = SZ_256K >> PAGE_SHIFT;

  	unsigned long cluster = max_cluster;

  	u64 new_align = ~((u64)SZ_128K - 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 = SZ_256K;

  	/*
  	 * 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_array(max_cluster, sizeof(struct page *),

  			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_SHIFT;

  	} else {

  		last_index = (isize - 1) >> PAGE_SHIFT;

  	}

  	if (newer_than) {
  		ret = find_new_extents(root, inode, newer_than,

  				       &newer_off, SZ_64K);

  		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_SHIFT;

  		} else
  			goto out_ra;
  	} else {

  		i = range->start >> PAGE_SHIFT;

  	}
  	if (!max_to_defrag)

  		max_to_defrag = last_index - i + 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 < DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE))) {

  		/*
  		 * 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)) {

  			btrfs_debug(root->fs_info, "defrag_file cancelled");

  			ret = -EAGAIN;
  			break;
  		}

  		if (!should_defrag_range(inode, (u64)i << PAGE_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 = DIV_ROUND_UP(skip, PAGE_SIZE);

  			i = max(i + 1, next);
  			continue;
  		}

  
  		if (!newer_than) {

  			cluster = (PAGE_ALIGN(defrag_end) >>
  				   PAGE_SHIFT) - i;

  			cluster = min(cluster, max_cluster);
  		} else {
  			cluster = max_cluster;
  		}

  		if (i + cluster > ra_index) {
  			ra_index = max(i, ra_index);
  			btrfs_force_ra(inode->i_mapping, ra, file, ra_index,
  				       cluster);

  			ra_index += cluster;

  		}

  		inode_lock(inode);

  		if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS)
  			BTRFS_I(inode)->force_compress = compress_type;

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

  		if (ret < 0) {

  			inode_unlock(inode);

  			goto out_ra;

  		}

  
  		defrag_count += ret;

  		balance_dirty_pages_ratelimited(inode->i_mapping);

  		inode_unlock(inode);

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

  			if (ret > 0)
  				i += ret;

  			newer_off = max(newer_off + 1,

  					(u64)i << PAGE_SHIFT);

  			ret = find_new_extents(root, inode, newer_than,
  					       &newer_off, SZ_64K);

  			if (!ret) {
  				range->start = newer_off;

  				i = (newer_off & new_align) >> PAGE_SHIFT;

  			} else {
  				break;

  			}

  		} else {

  			if (ret > 0) {

  				i += ret;

  				last_len += ret << PAGE_SHIFT;

  			} else {

  				i++;

  				last_len = 0;
  			}

  		}

  	}

  	if ((range->flags & BTRFS_DEFRAG_RANGE_START_IO)) {

  		filemap_flush(inode->i_mapping);

  		if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
  			     &BTRFS_I(inode)->runtime_flags))
  			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);

  	}

  	if (range->compress_type == BTRFS_COMPRESS_LZO) {

  		btrfs_set_fs_incompat(root->fs_info, COMPRESS_LZO);

  	}

  	ret = defrag_count;

  out_ra:

  	if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS) {

  		inode_lock(inode);

  		BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_NONE;

  		inode_unlock(inode);

  	}

  	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 *retptr;

  	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)) {

  		mnt_drop_write_file(file);

  		return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;

  	}

  	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) {

  		sizestr = devstr + 1;
  		*devstr = '\0';
  		devstr = vol_args->name;

  		ret = kstrtoull(devstr, 10, &devid);
  		if (ret)
  			goto out_free;

  		if (!devid) {
  			ret = -EINVAL;
  			goto out_free;
  		}

  		btrfs_info(root->fs_info, "resizing devid %llu", devid);

  	}

  	device = btrfs_find_device(root->fs_info, devid, NULL, NULL);

  	if (!device) {

  		btrfs_info(root->fs_info, "resizer unable to find device %llu",

  		       devid);

  		ret = -ENODEV;

  		goto out_free;

  	}

  
  	if (!device->writeable) {

  		btrfs_info(root->fs_info,
  			   "resizer unable to apply on readonly device %llu",

  		       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, &retptr);
  		if (*retptr != '\0' || new_size == 0) {

  			ret = -EINVAL;

  			goto out_free;

  		}
  	}

  	if (device->is_tgtdev_for_dev_replace) {

  		ret = -EPERM;

  		goto out_free;
  	}