/*
   * 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/blkdev.h>

  #include <linux/module.h>

  #include <linux/buffer_head.h>

  #include <linux/fs.h>
  #include <linux/pagemap.h>
  #include <linux/highmem.h>
  #include <linux/time.h>
  #include <linux/init.h>

  #include <linux/seq_file.h>

  #include <linux/string.h>

  #include <linux/backing-dev.h>

  #include <linux/mount.h>

  #include <linux/mpage.h>

  #include <linux/swap.h>
  #include <linux/writeback.h>

  #include <linux/statfs.h>

  #include <linux/compat.h>

  #include <linux/parser.h>

  #include <linux/ctype.h>

  #include <linux/namei.h>

  #include <linux/miscdevice.h>

  #include <linux/magic.h>

  #include <linux/slab.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 "xattr.h"

  #include "volumes.h"

  #include "version.h"

  #include "export.h"

  #include "compression.h"

  static const struct super_operations btrfs_super_ops;

  static const char *btrfs_decode_error(struct btrfs_fs_info *fs_info, int errno,
  				      char nbuf[16])
  {
  	char *errstr = NULL;
  
  	switch (errno) {
  	case -EIO:
  		errstr = "IO failure";
  		break;
  	case -ENOMEM:
  		errstr = "Out of memory";
  		break;
  	case -EROFS:
  		errstr = "Readonly filesystem";
  		break;
  	default:
  		if (nbuf) {
  			if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
  				errstr = nbuf;
  		}
  		break;
  	}
  
  	return errstr;
  }
  
  static void __save_error_info(struct btrfs_fs_info *fs_info)
  {
  	/*
  	 * today we only save the error info into ram.  Long term we'll
  	 * also send it down to the disk
  	 */
  	fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR;
  }
  
  /* NOTE:
   *	We move write_super stuff at umount in order to avoid deadlock
   *	for umount hold all lock.
   */
  static void save_error_info(struct btrfs_fs_info *fs_info)
  {
  	__save_error_info(fs_info);
  }
  
  /* btrfs handle error by forcing the filesystem readonly */
  static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
  {
  	struct super_block *sb = fs_info->sb;
  
  	if (sb->s_flags & MS_RDONLY)
  		return;
  
  	if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  		sb->s_flags |= MS_RDONLY;
  		printk(KERN_INFO "btrfs is forced readonly
  ");
  	}
  }
  
  /*
   * __btrfs_std_error decodes expected errors from the caller and
   * invokes the approciate error response.
   */
  void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
  		     unsigned int line, int errno)
  {
  	struct super_block *sb = fs_info->sb;
  	char nbuf[16];
  	const char *errstr;
  
  	/*
  	 * Special case: if the error is EROFS, and we're already
  	 * under MS_RDONLY, then it is safe here.
  	 */
  	if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
  		return;
  
  	errstr = btrfs_decode_error(fs_info, errno, nbuf);
  	printk(KERN_CRIT "BTRFS error (device %s) in %s:%d: %s
  ",
  		sb->s_id, function, line, errstr);
  	save_error_info(fs_info);
  
  	btrfs_handle_error(fs_info);
  }

  static void btrfs_put_super(struct super_block *sb)

  {

  	struct btrfs_root *root = btrfs_sb(sb);

  	int ret;

  	ret = close_ctree(root);

  	sb->s_fs_info = NULL;

  
  	(void)ret; /* FIXME: need to fix VFS to return error? */

  }

  enum {

  	Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,

  	Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
  	Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,

  	Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
  	Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
  	Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed, Opt_err,

  };
  
  static match_table_t tokens = {

  	{Opt_degraded, "degraded"},

  	{Opt_subvol, "subvol=%s"},

  	{Opt_subvolid, "subvolid=%d"},

  	{Opt_device, "device=%s"},

  	{Opt_nodatasum, "nodatasum"},

  	{Opt_nodatacow, "nodatacow"},

  	{Opt_nobarrier, "nobarrier"},

  	{Opt_max_inline, "max_inline=%s"},

  	{Opt_alloc_start, "alloc_start=%s"},

  	{Opt_thread_pool, "thread_pool=%d"},

  	{Opt_compress, "compress"},

  	{Opt_compress_type, "compress=%s"},

  	{Opt_compress_force, "compress-force"},

  	{Opt_compress_force_type, "compress-force=%s"},

  	{Opt_ssd, "ssd"},

  	{Opt_ssd_spread, "ssd_spread"},

  	{Opt_nossd, "nossd"},

  	{Opt_noacl, "noacl"},

  	{Opt_notreelog, "notreelog"},

  	{Opt_flushoncommit, "flushoncommit"},

  	{Opt_ratio, "metadata_ratio=%d"},

  	{Opt_discard, "discard"},

  	{Opt_space_cache, "space_cache"},

  	{Opt_clear_cache, "clear_cache"},

  	{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},

  	{Opt_err, NULL},

  };

  /*
   * Regular mount options parser.  Everything that is needed only when
   * reading in a new superblock is parsed here.
   */
  int btrfs_parse_options(struct btrfs_root *root, char *options)

  {

  	struct btrfs_fs_info *info = root->fs_info;

  	substring_t args[MAX_OPT_ARGS];

  	char *p, *num, *orig;

  	int intarg;

  	int ret = 0;

  	char *compress_type;
  	bool compress_force = false;

  	if (!options)

  		return 0;

  	/*
  	 * strsep changes the string, duplicate it because parse_options
  	 * gets called twice
  	 */
  	options = kstrdup(options, GFP_NOFS);
  	if (!options)
  		return -ENOMEM;

  	orig = options;

  	while ((p = strsep(&options, ",")) != NULL) {

  		int token;
  		if (!*p)
  			continue;
  
  		token = match_token(p, tokens, args);
  		switch (token) {

  		case Opt_degraded:

  			printk(KERN_INFO "btrfs: allowing degraded mounts
  ");
  			btrfs_set_opt(info->mount_opt, DEGRADED);

  			break;

  		case Opt_subvol:

  		case Opt_subvolid:

  		case Opt_device:

  			/*

  			 * These are parsed by btrfs_parse_early_options

  			 * and can be happily ignored here.
  			 */

  			break;
  		case Opt_nodatasum:

  			printk(KERN_INFO "btrfs: setting nodatasum
  ");

  			btrfs_set_opt(info->mount_opt, NODATASUM);

  			break;
  		case Opt_nodatacow:

  			printk(KERN_INFO "btrfs: setting nodatacow
  ");
  			btrfs_set_opt(info->mount_opt, NODATACOW);
  			btrfs_set_opt(info->mount_opt, NODATASUM);

  			break;

  		case Opt_compress_force:

  		case Opt_compress_force_type:
  			compress_force = true;
  		case Opt_compress:
  		case Opt_compress_type:
  			if (token == Opt_compress ||
  			    token == Opt_compress_force ||
  			    strcmp(args[0].from, "zlib") == 0) {
  				compress_type = "zlib";
  				info->compress_type = BTRFS_COMPRESS_ZLIB;

  			} else if (strcmp(args[0].from, "lzo") == 0) {
  				compress_type = "lzo";
  				info->compress_type = BTRFS_COMPRESS_LZO;

  			} else {
  				ret = -EINVAL;
  				goto out;
  			}

  			btrfs_set_opt(info->mount_opt, COMPRESS);

  			if (compress_force) {
  				btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
  				pr_info("btrfs: force %s compression
  ",
  					compress_type);
  			} else
  				pr_info("btrfs: use %s compression
  ",
  					compress_type);

  			break;

  		case Opt_ssd:

  			printk(KERN_INFO "btrfs: use ssd allocation scheme
  ");
  			btrfs_set_opt(info->mount_opt, SSD);

  			break;

  		case Opt_ssd_spread:
  			printk(KERN_INFO "btrfs: use spread ssd "
  			       "allocation scheme
  ");
  			btrfs_set_opt(info->mount_opt, SSD);
  			btrfs_set_opt(info->mount_opt, SSD_SPREAD);
  			break;

  		case Opt_nossd:

  			printk(KERN_INFO "btrfs: not using ssd allocation "
  			       "scheme
  ");

  			btrfs_set_opt(info->mount_opt, NOSSD);

  			btrfs_clear_opt(info->mount_opt, SSD);

  			btrfs_clear_opt(info->mount_opt, SSD_SPREAD);

  			break;

  		case Opt_nobarrier:

  			printk(KERN_INFO "btrfs: turning off barriers
  ");
  			btrfs_set_opt(info->mount_opt, NOBARRIER);

  			break;

  		case Opt_thread_pool:
  			intarg = 0;
  			match_int(&args[0], &intarg);
  			if (intarg) {
  				info->thread_pool_size = intarg;
  				printk(KERN_INFO "btrfs: thread pool %d
  ",
  				       info->thread_pool_size);
  			}
  			break;

  		case Opt_max_inline:

  			num = match_strdup(&args[0]);
  			if (num) {

  				info->max_inline = memparse(num, NULL);

  				kfree(num);

  				if (info->max_inline) {
  					info->max_inline = max_t(u64,
  						info->max_inline,
  						root->sectorsize);
  				}

  				printk(KERN_INFO "btrfs: max_inline at %llu
  ",

  					(unsigned long long)info->max_inline);

  			}
  			break;

  		case Opt_alloc_start:

  			num = match_strdup(&args[0]);
  			if (num) {

  				info->alloc_start = memparse(num, NULL);

  				kfree(num);
  				printk(KERN_INFO
  					"btrfs: allocations start at %llu
  ",

  					(unsigned long long)info->alloc_start);

  			}
  			break;

  		case Opt_noacl:
  			root->fs_info->sb->s_flags &= ~MS_POSIXACL;
  			break;

  		case Opt_notreelog:
  			printk(KERN_INFO "btrfs: disabling tree log
  ");
  			btrfs_set_opt(info->mount_opt, NOTREELOG);
  			break;

  		case Opt_flushoncommit:
  			printk(KERN_INFO "btrfs: turning on flush-on-commit
  ");
  			btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
  			break;

  		case Opt_ratio:
  			intarg = 0;
  			match_int(&args[0], &intarg);
  			if (intarg) {
  				info->metadata_ratio = intarg;
  				printk(KERN_INFO "btrfs: metadata ratio %d
  ",
  				       info->metadata_ratio);
  			}
  			break;

  		case Opt_discard:
  			btrfs_set_opt(info->mount_opt, DISCARD);
  			break;

  		case Opt_space_cache:
  			printk(KERN_INFO "btrfs: enabling disk space caching
  ");
  			btrfs_set_opt(info->mount_opt, SPACE_CACHE);

  			break;

  		case Opt_clear_cache:
  			printk(KERN_INFO "btrfs: force clearing of disk cache
  ");
  			btrfs_set_opt(info->mount_opt, CLEAR_CACHE);

  			break;

  		case Opt_user_subvol_rm_allowed:
  			btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
  			break;

  		case Opt_err:
  			printk(KERN_INFO "btrfs: unrecognized mount option "
  			       "'%s'
  ", p);
  			ret = -EINVAL;
  			goto out;

  		default:

  			break;

  		}
  	}

  out:

  	kfree(orig);

  	return ret;

  }
  
  /*
   * Parse mount options that are required early in the mount process.
   *
   * All other options will be parsed on much later in the mount process and
   * only when we need to allocate a new super block.
   */

  static int btrfs_parse_early_options(const char *options, fmode_t flags,

  		void *holder, char **subvol_name, u64 *subvol_objectid,

  		struct btrfs_fs_devices **fs_devices)

  {
  	substring_t args[MAX_OPT_ARGS];
  	char *opts, *p;
  	int error = 0;

  	int intarg;

  
  	if (!options)
  		goto out;
  
  	/*
  	 * strsep changes the string, duplicate it because parse_options
  	 * gets called twice
  	 */
  	opts = kstrdup(options, GFP_KERNEL);
  	if (!opts)
  		return -ENOMEM;
  
  	while ((p = strsep(&opts, ",")) != NULL) {
  		int token;
  		if (!*p)
  			continue;
  
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case Opt_subvol:
  			*subvol_name = match_strdup(&args[0]);
  			break;

  		case Opt_subvolid:
  			intarg = 0;

  			error = match_int(&args[0], &intarg);
  			if (!error) {
  				/* we want the original fs_tree */
  				if (!intarg)
  					*subvol_objectid =
  						BTRFS_FS_TREE_OBJECTID;
  				else
  					*subvol_objectid = intarg;
  			}

  			break;

  		case Opt_device:
  			error = btrfs_scan_one_device(match_strdup(&args[0]),
  					flags, holder, fs_devices);
  			if (error)
  				goto out_free_opts;
  			break;

  		default:
  			break;
  		}
  	}

   out_free_opts:

  	kfree(opts);
   out:
  	/*
  	 * If no subvolume name is specified we use the default one.  Allocate

  	 * a copy of the string "." here so that code later in the

  	 * mount path doesn't care if it's the default volume or another one.
  	 */
  	if (!*subvol_name) {

  		*subvol_name = kstrdup(".", GFP_KERNEL);

  		if (!*subvol_name)
  			return -ENOMEM;
  	}
  	return error;

  }

  static struct dentry *get_default_root(struct super_block *sb,
  				       u64 subvol_objectid)
  {
  	struct btrfs_root *root = sb->s_fs_info;
  	struct btrfs_root *new_root;
  	struct btrfs_dir_item *di;
  	struct btrfs_path *path;
  	struct btrfs_key location;
  	struct inode *inode;
  	struct dentry *dentry;
  	u64 dir_id;
  	int new = 0;
  
  	/*
  	 * We have a specific subvol we want to mount, just setup location and
  	 * go look up the root.
  	 */
  	if (subvol_objectid) {
  		location.objectid = subvol_objectid;
  		location.type = BTRFS_ROOT_ITEM_KEY;
  		location.offset = (u64)-1;
  		goto find_root;
  	}
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return ERR_PTR(-ENOMEM);
  	path->leave_spinning = 1;
  
  	/*
  	 * Find the "default" dir item which points to the root item that we
  	 * will mount by default if we haven't been given a specific subvolume
  	 * to mount.
  	 */
  	dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
  	di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);

  	if (IS_ERR(di))
  		return ERR_CAST(di);

  	if (!di) {
  		/*
  		 * Ok the default dir item isn't there.  This is weird since
  		 * it's always been there, but don't freak out, just try and
  		 * mount to root most subvolume.
  		 */
  		btrfs_free_path(path);
  		dir_id = BTRFS_FIRST_FREE_OBJECTID;
  		new_root = root->fs_info->fs_root;
  		goto setup_root;
  	}
  
  	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
  	btrfs_free_path(path);
  
  find_root:
  	new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
  	if (IS_ERR(new_root))

  		return ERR_CAST(new_root);

  
  	if (btrfs_root_refs(&new_root->root_item) == 0)
  		return ERR_PTR(-ENOENT);
  
  	dir_id = btrfs_root_dirid(&new_root->root_item);
  setup_root:
  	location.objectid = dir_id;
  	location.type = BTRFS_INODE_ITEM_KEY;
  	location.offset = 0;
  
  	inode = btrfs_iget(sb, &location, new_root, &new);

  	if (IS_ERR(inode))
  		return ERR_CAST(inode);

  
  	/*
  	 * If we're just mounting the root most subvol put the inode and return
  	 * a reference to the dentry.  We will have already gotten a reference
  	 * to the inode in btrfs_fill_super so we're good to go.
  	 */
  	if (!new && sb->s_root->d_inode == inode) {
  		iput(inode);
  		return dget(sb->s_root);
  	}
  
  	if (new) {
  		const struct qstr name = { .name = "/", .len = 1 };
  
  		/*
  		 * New inode, we need to make the dentry a sibling of s_root so
  		 * everything gets cleaned up properly on unmount.
  		 */
  		dentry = d_alloc(sb->s_root, &name);
  		if (!dentry) {
  			iput(inode);
  			return ERR_PTR(-ENOMEM);
  		}
  		d_splice_alias(inode, dentry);
  	} else {
  		/*
  		 * We found the inode in cache, just find a dentry for it and
  		 * put the reference to the inode we just got.
  		 */
  		dentry = d_find_alias(inode);
  		iput(inode);
  	}
  
  	return dentry;
  }

  static int btrfs_fill_super(struct super_block *sb,

  			    struct btrfs_fs_devices *fs_devices,

  			    void *data, int silent)

  {

  	struct inode *inode;
  	struct dentry *root_dentry;

  	struct btrfs_root *tree_root;

  	struct btrfs_key key;

  	int err;

  	sb->s_maxbytes = MAX_LFS_FILESIZE;
  	sb->s_magic = BTRFS_SUPER_MAGIC;
  	sb->s_op = &btrfs_super_ops;

  	sb->s_d_op = &btrfs_dentry_operations;

  	sb->s_export_op = &btrfs_export_ops;

  	sb->s_xattr = btrfs_xattr_handlers;

  	sb->s_time_gran = 1;

  #ifdef CONFIG_BTRFS_FS_POSIX_ACL

  	sb->s_flags |= MS_POSIXACL;

  #endif

  	tree_root = open_ctree(sb, fs_devices, (char *)data);

  	if (IS_ERR(tree_root)) {

  		printk("btrfs: open_ctree failed
  ");

  		return PTR_ERR(tree_root);

  	}

  	sb->s_fs_info = tree_root;

  	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
  	key.type = BTRFS_INODE_ITEM_KEY;
  	key.offset = 0;

  	inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);

  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);

  		goto fail_close;

  	}

  	root_dentry = d_alloc_root(inode);
  	if (!root_dentry) {
  		iput(inode);
  		err = -ENOMEM;
  		goto fail_close;

  	}

  	sb->s_root = root_dentry;

  	save_mount_options(sb, data);

  	return 0;

  
  fail_close:
  	close_ctree(tree_root);
  	return err;

  }

  int btrfs_sync_fs(struct super_block *sb, int wait)

  {
  	struct btrfs_trans_handle *trans;

  	struct btrfs_root *root = btrfs_sb(sb);

  	int ret;

  	if (!wait) {
  		filemap_flush(root->fs_info->btree_inode->i_mapping);
  		return 0;
  	}

  	btrfs_start_delalloc_inodes(root, 0);
  	btrfs_wait_ordered_extents(root, 0, 0);

  	trans = btrfs_start_transaction(root, 0);

  	ret = btrfs_commit_transaction(trans, root);

  	return ret;

  }

  static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
  {
  	struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
  	struct btrfs_fs_info *info = root->fs_info;
  
  	if (btrfs_test_opt(root, DEGRADED))
  		seq_puts(seq, ",degraded");
  	if (btrfs_test_opt(root, NODATASUM))
  		seq_puts(seq, ",nodatasum");
  	if (btrfs_test_opt(root, NODATACOW))
  		seq_puts(seq, ",nodatacow");
  	if (btrfs_test_opt(root, NOBARRIER))
  		seq_puts(seq, ",nobarrier");

  	if (info->max_inline != 8192 * 1024)

  		seq_printf(seq, ",max_inline=%llu",
  			   (unsigned long long)info->max_inline);

  	if (info->alloc_start != 0)

  		seq_printf(seq, ",alloc_start=%llu",
  			   (unsigned long long)info->alloc_start);

  	if (info->thread_pool_size !=  min_t(unsigned long,
  					     num_online_cpus() + 2, 8))
  		seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
  	if (btrfs_test_opt(root, COMPRESS))
  		seq_puts(seq, ",compress");

  	if (btrfs_test_opt(root, NOSSD))
  		seq_puts(seq, ",nossd");

  	if (btrfs_test_opt(root, SSD_SPREAD))
  		seq_puts(seq, ",ssd_spread");
  	else if (btrfs_test_opt(root, SSD))

  		seq_puts(seq, ",ssd");

  	if (btrfs_test_opt(root, NOTREELOG))

  		seq_puts(seq, ",notreelog");

  	if (btrfs_test_opt(root, FLUSHONCOMMIT))

  		seq_puts(seq, ",flushoncommit");

  	if (btrfs_test_opt(root, DISCARD))
  		seq_puts(seq, ",discard");

  	if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
  		seq_puts(seq, ",noacl");
  	return 0;
  }

  static int btrfs_test_super(struct super_block *s, void *data)

  {

  	struct btrfs_root *test_root = data;

  	struct btrfs_root *root = btrfs_sb(s);

  	/*
  	 * If this super block is going away, return false as it
  	 * can't match as an existing super block.
  	 */
  	if (!atomic_read(&s->s_active))
  		return 0;

  	return root->fs_info->fs_devices == test_root->fs_info->fs_devices;

  }

  static int btrfs_set_super(struct super_block *s, void *data)
  {
  	s->s_fs_info = data;
  
  	return set_anon_super(s, data);

  }

  /*
   * Find a superblock for the given device / mount point.
   *
   * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
   *	  for multiple device setup.  Make sure to keep it in sync.
   */

  static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
  		const char *dev_name, void *data)

  {
  	struct block_device *bdev = NULL;
  	struct super_block *s;
  	struct dentry *root;

  	struct btrfs_fs_devices *fs_devices = NULL;

  	struct btrfs_root *tree_root = NULL;
  	struct btrfs_fs_info *fs_info = NULL;

  	fmode_t mode = FMODE_READ;

  	char *subvol_name = NULL;
  	u64 subvol_objectid = 0;

  	int error = 0;

  	if (!(flags & MS_RDONLY))
  		mode |= FMODE_WRITE;
  
  	error = btrfs_parse_early_options(data, mode, fs_type,

  					  &subvol_name, &subvol_objectid,
  					  &fs_devices);

  	if (error)

  		return ERR_PTR(error);

  	error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);

  	if (error)

  		goto error_free_subvol_name;

  	error = btrfs_open_devices(fs_devices, mode, fs_type);

  	if (error)

  		goto error_free_subvol_name;

  	if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
  		error = -EACCES;
  		goto error_close_devices;
  	}

  	/*
  	 * Setup a dummy root and fs_info for test/set super.  This is because
  	 * we don't actually fill this stuff out until open_ctree, but we need
  	 * it for searching for existing supers, so this lets us do that and
  	 * then open_ctree will properly initialize everything later.
  	 */
  	fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
  	tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
  	if (!fs_info || !tree_root) {
  		error = -ENOMEM;
  		goto error_close_devices;
  	}
  	fs_info->tree_root = tree_root;
  	fs_info->fs_devices = fs_devices;
  	tree_root->fs_info = fs_info;

  	bdev = fs_devices->latest_bdev;

  	s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);

  	if (IS_ERR(s))
  		goto error_s;
  
  	if (s->s_root) {
  		if ((flags ^ s->s_flags) & MS_RDONLY) {

  			deactivate_locked_super(s);

  			error = -EBUSY;

  			goto error_close_devices;

  		}

  		btrfs_close_devices(fs_devices);

  	} else {
  		char b[BDEVNAME_SIZE];
  
  		s->s_flags = flags;
  		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));

  		error = btrfs_fill_super(s, fs_devices, data,
  					 flags & MS_SILENT ? 1 : 0);

  		if (error) {

  			deactivate_locked_super(s);

  			goto error_free_subvol_name;

  		}

  		btrfs_sb(s)->fs_info->bdev_holder = fs_type;

  		s->s_flags |= MS_ACTIVE;
  	}

  	root = get_default_root(s, subvol_objectid);
  	if (IS_ERR(root)) {
  		error = PTR_ERR(root);
  		deactivate_locked_super(s);

  		goto error_free_subvol_name;

  	}
  	/* if they gave us a subvolume name bind mount into that */
  	if (strcmp(subvol_name, ".")) {
  		struct dentry *new_root;
  		mutex_lock(&root->d_inode->i_mutex);
  		new_root = lookup_one_len(subvol_name, root,

  				      strlen(subvol_name));

  		mutex_unlock(&root->d_inode->i_mutex);

  		if (IS_ERR(new_root)) {

  			dput(root);

  			deactivate_locked_super(s);

  			error = PTR_ERR(new_root);

  			goto error_free_subvol_name;

  		}

  		if (!new_root->d_inode) {

  			dput(root);

  			dput(new_root);

  			deactivate_locked_super(s);

  			error = -ENXIO;

  			goto error_free_subvol_name;

  		}

  		dput(root);
  		root = new_root;

  	}

  	kfree(subvol_name);

  	return root;

  
  error_s:
  	error = PTR_ERR(s);

  error_close_devices:

  	btrfs_close_devices(fs_devices);

  	kfree(fs_info);
  	kfree(tree_root);

  error_free_subvol_name:
  	kfree(subvol_name);

  	return ERR_PTR(error);

  }

  static int btrfs_remount(struct super_block *sb, int *flags, char *data)
  {
  	struct btrfs_root *root = btrfs_sb(sb);
  	int ret;

  	ret = btrfs_parse_options(root, data);
  	if (ret)
  		return -EINVAL;

  	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
  		return 0;
  
  	if (*flags & MS_RDONLY) {
  		sb->s_flags |= MS_RDONLY;
  
  		ret =  btrfs_commit_super(root);
  		WARN_ON(ret);
  	} else {

  		if (root->fs_info->fs_devices->rw_devices == 0)
  			return -EACCES;

  		if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
  			return -EINVAL;

  		ret = btrfs_cleanup_fs_roots(root->fs_info);

  		WARN_ON(ret);

  		/* recover relocation */
  		ret = btrfs_recover_relocation(root);

  		WARN_ON(ret);
  
  		sb->s_flags &= ~MS_RDONLY;
  	}
  
  	return 0;
  }

  /*
   * The helper to calc the free space on the devices that can be used to store
   * file data.
   */
  static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
  {
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	struct btrfs_device_info *devices_info;
  	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
  	struct btrfs_device *device;
  	u64 skip_space;
  	u64 type;
  	u64 avail_space;
  	u64 used_space;
  	u64 min_stripe_size;
  	int min_stripes = 1;
  	int i = 0, nr_devices;
  	int ret;
  
  	nr_devices = fs_info->fs_devices->rw_devices;
  	BUG_ON(!nr_devices);
  
  	devices_info = kmalloc(sizeof(*devices_info) * nr_devices,
  			       GFP_NOFS);
  	if (!devices_info)
  		return -ENOMEM;
  
  	/* calc min stripe number for data space alloction */
  	type = btrfs_get_alloc_profile(root, 1);
  	if (type & BTRFS_BLOCK_GROUP_RAID0)
  		min_stripes = 2;
  	else if (type & BTRFS_BLOCK_GROUP_RAID1)
  		min_stripes = 2;
  	else if (type & BTRFS_BLOCK_GROUP_RAID10)
  		min_stripes = 4;
  
  	if (type & BTRFS_BLOCK_GROUP_DUP)
  		min_stripe_size = 2 * BTRFS_STRIPE_LEN;
  	else
  		min_stripe_size = BTRFS_STRIPE_LEN;
  
  	list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
  		if (!device->in_fs_metadata)
  			continue;
  
  		avail_space = device->total_bytes - device->bytes_used;
  
  		/* align with stripe_len */
  		do_div(avail_space, BTRFS_STRIPE_LEN);
  		avail_space *= BTRFS_STRIPE_LEN;
  
  		/*
  		 * In order to avoid overwritting the superblock on the drive,
  		 * btrfs starts at an offset of at least 1MB when doing chunk
  		 * allocation.
  		 */
  		skip_space = 1024 * 1024;
  
  		/* user can set the offset in fs_info->alloc_start. */
  		if (fs_info->alloc_start + BTRFS_STRIPE_LEN <=
  		    device->total_bytes)
  			skip_space = max(fs_info->alloc_start, skip_space);
  
  		/*
  		 * btrfs can not use the free space in [0, skip_space - 1],
  		 * we must subtract it from the total. In order to implement
  		 * it, we account the used space in this range first.
  		 */
  		ret = btrfs_account_dev_extents_size(device, 0, skip_space - 1,
  						     &used_space);
  		if (ret) {
  			kfree(devices_info);
  			return ret;
  		}
  
  		/* calc the free space in [0, skip_space - 1] */
  		skip_space -= used_space;
  
  		/*
  		 * we can use the free space in [0, skip_space - 1], subtract
  		 * it from the total.
  		 */
  		if (avail_space && avail_space >= skip_space)
  			avail_space -= skip_space;
  		else
  			avail_space = 0;
  
  		if (avail_space < min_stripe_size)
  			continue;
  
  		devices_info[i].dev = device;
  		devices_info[i].max_avail = avail_space;
  
  		i++;
  	}
  
  	nr_devices = i;
  
  	btrfs_descending_sort_devices(devices_info, nr_devices);
  
  	i = nr_devices - 1;
  	avail_space = 0;
  	while (nr_devices >= min_stripes) {
  		if (devices_info[i].max_avail >= min_stripe_size) {
  			int j;
  			u64 alloc_size;
  
  			avail_space += devices_info[i].max_avail * min_stripes;
  			alloc_size = devices_info[i].max_avail;
  			for (j = i + 1 - min_stripes; j <= i; j++)
  				devices_info[j].max_avail -= alloc_size;
  		}
  		i--;
  		nr_devices--;
  	}
  
  	kfree(devices_info);
  	*free_bytes = avail_space;
  	return 0;
  }

  static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  {
  	struct btrfs_root *root = btrfs_sb(dentry->d_sb);

  	struct btrfs_super_block *disk_super = &root->fs_info->super_copy;

  	struct list_head *head = &root->fs_info->space_info;
  	struct btrfs_space_info *found;
  	u64 total_used = 0;

  	u64 total_free_data = 0;

  	int bits = dentry->d_sb->s_blocksize_bits;

  	__be32 *fsid = (__be32 *)root->fs_info->fsid;

  	int ret;

  	/* holding chunk_muext to avoid allocating new chunks */
  	mutex_lock(&root->fs_info->chunk_mutex);

  	rcu_read_lock();

  	list_for_each_entry_rcu(found, head, list) {

  		if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
  			total_free_data += found->disk_total - found->disk_used;
  			total_free_data -=
  				btrfs_account_ro_block_groups_free_space(found);
  		}

  		total_used += found->disk_used;

  	}

  	rcu_read_unlock();

  	buf->f_namelen = BTRFS_NAME_LEN;

  	buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;

  	buf->f_bfree = buf->f_blocks - (total_used >> bits);

  	buf->f_bsize = dentry->d_sb->s_blocksize;
  	buf->f_type = BTRFS_SUPER_MAGIC;

  	buf->f_bavail = total_free_data;
  	ret = btrfs_calc_avail_data_space(root, &total_free_data);
  	if (ret) {
  		mutex_unlock(&root->fs_info->chunk_mutex);
  		return ret;
  	}
  	buf->f_bavail += total_free_data;
  	buf->f_bavail = buf->f_bavail >> bits;
  	mutex_unlock(&root->fs_info->chunk_mutex);

  	/* We treat it as constant endianness (it doesn't matter _which_)

  	   because we want the fsid to come out the same whether mounted

  	   on a big-endian or little-endian host */
  	buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
  	buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);

  	/* Mask in the root object ID too, to disambiguate subvols */
  	buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
  	buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;

  	return 0;
  }

  static struct file_system_type btrfs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "btrfs",

  	.mount		= btrfs_mount,

  	.kill_sb	= kill_anon_super,

  	.fs_flags	= FS_REQUIRES_DEV,
  };

  /*
   * used by btrfsctl to scan devices when no FS is mounted
   */

  static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
  				unsigned long arg)
  {
  	struct btrfs_ioctl_vol_args *vol;
  	struct btrfs_fs_devices *fs_devices;

  	int ret = -ENOTTY;

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

  	vol = memdup_user((void __user *)arg, sizeof(*vol));
  	if (IS_ERR(vol))
  		return PTR_ERR(vol);

  	switch (cmd) {
  	case BTRFS_IOC_SCAN_DEV:

  		ret = btrfs_scan_one_device(vol->name, FMODE_READ,

  					    &btrfs_fs_type, &fs_devices);
  		break;
  	}

  	kfree(vol);

  	return ret;

  }

  static int btrfs_freeze(struct super_block *sb)

  {
  	struct btrfs_root *root = btrfs_sb(sb);

  	mutex_lock(&root->fs_info->transaction_kthread_mutex);
  	mutex_lock(&root->fs_info->cleaner_mutex);

  	return 0;

  }

  static int btrfs_unfreeze(struct super_block *sb)

  {
  	struct btrfs_root *root = btrfs_sb(sb);

  	mutex_unlock(&root->fs_info->cleaner_mutex);
  	mutex_unlock(&root->fs_info->transaction_kthread_mutex);

  	return 0;

  }

  static const struct super_operations btrfs_super_ops = {

  	.drop_inode	= btrfs_drop_inode,

  	.evict_inode	= btrfs_evict_inode,

  	.put_super	= btrfs_put_super,

  	.sync_fs	= btrfs_sync_fs,

  	.show_options	= btrfs_show_options,

  	.write_inode	= btrfs_write_inode,

  	.dirty_inode	= btrfs_dirty_inode,

  	.alloc_inode	= btrfs_alloc_inode,
  	.destroy_inode	= btrfs_destroy_inode,

  	.statfs		= btrfs_statfs,

  	.remount_fs	= btrfs_remount,

  	.freeze_fs	= btrfs_freeze,
  	.unfreeze_fs	= btrfs_unfreeze,

  };

  
  static const struct file_operations btrfs_ctl_fops = {
  	.unlocked_ioctl	 = btrfs_control_ioctl,
  	.compat_ioctl = btrfs_control_ioctl,
  	.owner	 = THIS_MODULE,

  	.llseek = noop_llseek,

  };
  
  static struct miscdevice btrfs_misc = {

  	.minor		= BTRFS_MINOR,

  	.name		= "btrfs-control",
  	.fops		= &btrfs_ctl_fops
  };

  MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
  MODULE_ALIAS("devname:btrfs-control");

  static int btrfs_interface_init(void)
  {
  	return misc_register(&btrfs_misc);
  }

  static void btrfs_interface_exit(void)

  {
  	if (misc_deregister(&btrfs_misc) < 0)

  		printk(KERN_INFO "misc_deregister failed for control device");

  }

  static int __init init_btrfs_fs(void)
  {

  	int err;

  
  	err = btrfs_init_sysfs();
  	if (err)
  		return err;

  	err = btrfs_init_compress();

  	if (err)

  		goto free_sysfs;

  	err = btrfs_init_cachep();
  	if (err)
  		goto free_compress;

  	err = extent_io_init();

  	if (err)
  		goto free_cachep;

  	err = extent_map_init();
  	if (err)
  		goto free_extent_io;

  	err = btrfs_interface_init();

  	if (err)
  		goto free_extent_map;

  	err = register_filesystem(&btrfs_fs_type);
  	if (err)
  		goto unregister_ioctl;

  
  	printk(KERN_INFO "%s loaded
  ", BTRFS_BUILD_VERSION);

  	return 0;

  unregister_ioctl:
  	btrfs_interface_exit();

  free_extent_map:
  	extent_map_exit();

  free_extent_io:
  	extent_io_exit();

  free_cachep:
  	btrfs_destroy_cachep();

  free_compress:
  	btrfs_exit_compress();

  free_sysfs:

  	btrfs_exit_sysfs();
  	return err;

  }
  
  static void __exit exit_btrfs_fs(void)
  {

  	btrfs_destroy_cachep();

  	extent_map_exit();

  	extent_io_exit();

  	btrfs_interface_exit();

  	unregister_filesystem(&btrfs_fs_type);

  	btrfs_exit_sysfs();

  	btrfs_cleanup_fs_uuids();

  	btrfs_exit_compress();

  }
  
  module_init(init_btrfs_fs)
  module_exit(exit_btrfs_fs)
  
  MODULE_LICENSE("GPL");