/*
   * Copyright (C) 2005, 2006

   * Avishay Traeger (avishay@gmail.com)

   * Copyright (C) 2008, 2009
   * Boaz Harrosh <bharrosh@panasas.com>
   *
   * Copyrights for code taken from ext2:
   *     Copyright (C) 1992, 1993, 1994, 1995
   *     Remy Card (card@masi.ibp.fr)
   *     Laboratoire MASI - Institut Blaise Pascal
   *     Universite Pierre et Marie Curie (Paris VI)
   *     from
   *     linux/fs/minix/inode.c
   *     Copyright (C) 1991, 1992  Linus Torvalds
   *
   * This file is part of exofs.
   *
   * exofs is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation.  Since it is based on ext2, and the only
   * valid version of GPL for the Linux kernel is version 2, the only valid
   * version of GPL for exofs is version 2.
   *
   * exofs 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 exofs; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  
  #include <linux/string.h>
  #include <linux/parser.h>
  #include <linux/vfs.h>
  #include <linux/random.h>

  #include <linux/exportfs.h>

  #include <linux/slab.h>

  
  #include "exofs.h"
  
  /******************************************************************************
   * MOUNT OPTIONS
   *****************************************************************************/
  
  /*
   * struct to hold what we get from mount options
   */
  struct exofs_mountopt {

  	bool is_osdname;

  	const char *dev_name;
  	uint64_t pid;
  	int timeout;
  };
  
  /*
   * exofs-specific mount-time options.
   */

  enum { Opt_name, Opt_pid, Opt_to, Opt_err };

  
  /*
   * Our mount-time options.  These should ideally be 64-bit unsigned, but the
   * kernel's parsing functions do not currently support that.  32-bit should be
   * sufficient for most applications now.
   */
  static match_table_t tokens = {

  	{Opt_name, "osdname=%s"},

  	{Opt_pid, "pid=%u"},
  	{Opt_to, "to=%u"},
  	{Opt_err, NULL}
  };
  
  /*
   * The main option parsing method.  Also makes sure that all of the mandatory
   * mount options were set.
   */
  static int parse_options(char *options, struct exofs_mountopt *opts)
  {
  	char *p;
  	substring_t args[MAX_OPT_ARGS];
  	int option;
  	bool s_pid = false;
  
  	EXOFS_DBGMSG("parse_options %s
  ", options);
  	/* defaults */
  	memset(opts, 0, sizeof(*opts));
  	opts->timeout = BLK_DEFAULT_SG_TIMEOUT;
  
  	while ((p = strsep(&options, ",")) != NULL) {
  		int token;
  		char str[32];
  
  		if (!*p)
  			continue;
  
  		token = match_token(p, tokens, args);
  		switch (token) {

  		case Opt_name:
  			opts->dev_name = match_strdup(&args[0]);
  			if (unlikely(!opts->dev_name)) {
  				EXOFS_ERR("Error allocating dev_name");
  				return -ENOMEM;
  			}
  			opts->is_osdname = true;
  			break;

  		case Opt_pid:
  			if (0 == match_strlcpy(str, &args[0], sizeof(str)))
  				return -EINVAL;
  			opts->pid = simple_strtoull(str, NULL, 0);
  			if (opts->pid < EXOFS_MIN_PID) {
  				EXOFS_ERR("Partition ID must be >= %u",
  					  EXOFS_MIN_PID);
  				return -EINVAL;
  			}
  			s_pid = 1;
  			break;
  		case Opt_to:
  			if (match_int(&args[0], &option))
  				return -EINVAL;
  			if (option <= 0) {
  				EXOFS_ERR("Timout must be > 0");
  				return -EINVAL;
  			}
  			opts->timeout = option * HZ;
  			break;
  		}
  	}
  
  	if (!s_pid) {
  		EXOFS_ERR("Need to specify the following options:
  ");
  		EXOFS_ERR("    -o pid=pid_no_to_use
  ");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  /******************************************************************************
   * INODE CACHE
   *****************************************************************************/
  
  /*
   * Our inode cache.  Isn't it pretty?
   */
  static struct kmem_cache *exofs_inode_cachep;
  
  /*
   * Allocate an inode in the cache
   */
  static struct inode *exofs_alloc_inode(struct super_block *sb)
  {
  	struct exofs_i_info *oi;
  
  	oi = kmem_cache_alloc(exofs_inode_cachep, GFP_KERNEL);
  	if (!oi)
  		return NULL;
  
  	oi->vfs_inode.i_version = 1;
  	return &oi->vfs_inode;
  }

  static void exofs_i_callback(struct rcu_head *head)
  {
  	struct inode *inode = container_of(head, struct inode, i_rcu);
  	INIT_LIST_HEAD(&inode->i_dentry);
  	kmem_cache_free(exofs_inode_cachep, exofs_i(inode));
  }

  /*
   * Remove an inode from the cache
   */
  static void exofs_destroy_inode(struct inode *inode)
  {

  	call_rcu(&inode->i_rcu, exofs_i_callback);

  }
  
  /*
   * Initialize the inode
   */
  static void exofs_init_once(void *foo)
  {
  	struct exofs_i_info *oi = foo;
  
  	inode_init_once(&oi->vfs_inode);
  }
  
  /*
   * Create and initialize the inode cache
   */
  static int init_inodecache(void)
  {
  	exofs_inode_cachep = kmem_cache_create("exofs_inode_cache",
  				sizeof(struct exofs_i_info), 0,
  				SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
  				exofs_init_once);
  	if (exofs_inode_cachep == NULL)
  		return -ENOMEM;
  	return 0;
  }
  
  /*
   * Destroy the inode cache
   */
  static void destroy_inodecache(void)
  {
  	kmem_cache_destroy(exofs_inode_cachep);
  }
  
  /******************************************************************************
   * SUPERBLOCK FUNCTIONS
   *****************************************************************************/
  static const struct super_operations exofs_sops;

  static const struct export_operations exofs_export_ops;

  static const struct osd_attr g_attr_sb_stats = ATTR_DEF(
  	EXOFS_APAGE_SB_DATA,
  	EXOFS_ATTR_SB_STATS,
  	sizeof(struct exofs_sb_stats));
  
  static int __sbi_read_stats(struct exofs_sb_info *sbi)
  {
  	struct osd_attr attrs[] = {
  		[0] = g_attr_sb_stats,
  	};
  	struct exofs_io_state *ios;
  	int ret;
  
  	ret = exofs_get_io_state(&sbi->layout, &ios);
  	if (unlikely(ret)) {
  		EXOFS_ERR("%s: exofs_get_io_state failed.
  ", __func__);
  		return ret;
  	}
  
  	ios->cred = sbi->s_cred;
  
  	ios->in_attr = attrs;
  	ios->in_attr_len = ARRAY_SIZE(attrs);
  
  	ret = exofs_sbi_read(ios);
  	if (unlikely(ret)) {
  		EXOFS_ERR("Error reading super_block stats => %d
  ", ret);
  		goto out;
  	}
  
  	ret = extract_attr_from_ios(ios, &attrs[0]);
  	if (ret) {
  		EXOFS_ERR("%s: extract_attr of sb_stats failed
  ", __func__);
  		goto out;
  	}
  	if (attrs[0].len) {
  		struct exofs_sb_stats *ess;
  
  		if (unlikely(attrs[0].len != sizeof(*ess))) {
  			EXOFS_ERR("%s: Wrong version of exofs_sb_stats "
  				  "size(%d) != expected(%zd)
  ",
  				  __func__, attrs[0].len, sizeof(*ess));
  			goto out;
  		}
  
  		ess = attrs[0].val_ptr;
  		sbi->s_nextid = le64_to_cpu(ess->s_nextid);
  		sbi->s_numfiles = le32_to_cpu(ess->s_numfiles);
  	}
  
  out:
  	exofs_put_io_state(ios);
  	return ret;
  }
  
  static void stats_done(struct exofs_io_state *ios, void *p)
  {
  	exofs_put_io_state(ios);
  	/* Good thanks nothing to do anymore */
  }
  
  /* Asynchronously write the stats attribute */
  int exofs_sbi_write_stats(struct exofs_sb_info *sbi)
  {
  	struct osd_attr attrs[] = {
  		[0] = g_attr_sb_stats,
  	};
  	struct exofs_io_state *ios;
  	int ret;
  
  	ret = exofs_get_io_state(&sbi->layout, &ios);
  	if (unlikely(ret)) {
  		EXOFS_ERR("%s: exofs_get_io_state failed.
  ", __func__);
  		return ret;
  	}
  
  	sbi->s_ess.s_nextid   = cpu_to_le64(sbi->s_nextid);
  	sbi->s_ess.s_numfiles = cpu_to_le64(sbi->s_numfiles);
  	attrs[0].val_ptr = &sbi->s_ess;
  
  	ios->cred = sbi->s_cred;
  	ios->done = stats_done;
  	ios->private = sbi;
  	ios->out_attr = attrs;
  	ios->out_attr_len = ARRAY_SIZE(attrs);
  
  	ret = exofs_sbi_write(ios);
  	if (unlikely(ret)) {
  		EXOFS_ERR("%s: exofs_sbi_write failed.
  ", __func__);
  		exofs_put_io_state(ios);
  	}
  
  	return ret;
  }

  /*
   * Write the superblock to the OSD
   */

  int exofs_sync_fs(struct super_block *sb, int wait)

  {
  	struct exofs_sb_info *sbi;
  	struct exofs_fscb *fscb;

  	struct exofs_io_state *ios;

  	int ret = -ENOMEM;

  	fscb = kmalloc(sizeof(*fscb), GFP_KERNEL);
  	if (unlikely(!fscb))
  		return -ENOMEM;

  	sbi = sb->s_fs_info;

  	/* NOTE: We no longer dirty the super_block anywhere in exofs. The
  	 * reason we write the fscb here on unmount is so we can stay backwards
  	 * compatible with fscb->s_version == 1. (What we are not compatible
  	 * with is if a new version FS crashed and then we try to mount an old
  	 * version). Otherwise the exofs_fscb is read-only from mkfs time. All
  	 * the writeable info is set in exofs_sbi_write_stats() above.
  	 */

  	ret = exofs_get_io_state(&sbi->layout, &ios);

  	if (unlikely(ret))

  		goto out;

  	lock_super(sb);

  	ios->length = offsetof(struct exofs_fscb, s_dev_table_oid);

  	memset(fscb, 0, ios->length);

  	fscb->s_nextid = cpu_to_le64(sbi->s_nextid);
  	fscb->s_numfiles = cpu_to_le32(sbi->s_numfiles);
  	fscb->s_magic = cpu_to_le16(sb->s_magic);
  	fscb->s_newfs = 0;

  	fscb->s_version = EXOFS_FSCB_VER;

  	ios->obj.id = EXOFS_SUPER_ID;
  	ios->offset = 0;
  	ios->kern_buff = fscb;
  	ios->cred = sbi->s_cred;

  	ret = exofs_sbi_write(ios);

  	if (unlikely(ret))

  		EXOFS_ERR("%s: exofs_sbi_write failed.
  ", __func__);

  	else
  		sb->s_dirt = 0;

  	unlock_super(sb);

  out:

  	EXOFS_DBGMSG("s_nextid=0x%llx ret=%d
  ", _LLU(sbi->s_nextid), ret);
  	exofs_put_io_state(ios);

  	kfree(fscb);

  	return ret;
  }
  
  static void exofs_write_super(struct super_block *sb)
  {
  	if (!(sb->s_flags & MS_RDONLY))
  		exofs_sync_fs(sb, 1);
  	else
  		sb->s_dirt = 0;

  }

  static void _exofs_print_device(const char *msg, const char *dev_path,
  				struct osd_dev *od, u64 pid)
  {
  	const struct osd_dev_info *odi = osduld_device_info(od);
  
  	printk(KERN_NOTICE "exofs: %s %s osd_name-%s pid-0x%llx
  ",
  		msg, dev_path ?: "", odi->osdname, _LLU(pid));
  }

  void exofs_free_sbi(struct exofs_sb_info *sbi)
  {

  	while (sbi->layout.s_numdevs) {
  		int i = --sbi->layout.s_numdevs;
  		struct osd_dev *od = sbi->layout.s_ods[i];

  
  		if (od) {

  			sbi->layout.s_ods[i] = NULL;

  			osduld_put_device(od);
  		}
  	}
  	kfree(sbi);
  }

  /*
   * This function is called when the vfs is freeing the superblock.  We just
   * need to free our own part.
   */
  static void exofs_put_super(struct super_block *sb)
  {
  	int num_pend;
  	struct exofs_sb_info *sbi = sb->s_fs_info;
  
  	/* make sure there are no pending commands */
  	for (num_pend = atomic_read(&sbi->s_curr_pending); num_pend > 0;
  	     num_pend = atomic_read(&sbi->s_curr_pending)) {
  		wait_queue_head_t wq;

  
  		printk(KERN_NOTICE "%s: !!Pending operations in flight. "
  		       "This is a BUG. please report to osd-dev@open-osd.org
  ",
  		       __func__);

  		init_waitqueue_head(&wq);
  		wait_event_timeout(wq,
  				  (atomic_read(&sbi->s_curr_pending) == 0),
  				  msecs_to_jiffies(100));
  	}

  	_exofs_print_device("Unmounting", NULL, sbi->layout.s_ods[0],
  			    sbi->layout.s_pid);

  	bdi_destroy(&sbi->bdi);

  	exofs_free_sbi(sbi);

  	sb->s_fs_info = NULL;
  }

  static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
  				    struct exofs_device_table *dt)
  {

  	u64 stripe_length;

  	sbi->data_map.odm_num_comps   =
  				le32_to_cpu(dt->dt_data_map.cb_num_comps);
  	sbi->data_map.odm_stripe_unit =
  				le64_to_cpu(dt->dt_data_map.cb_stripe_unit);
  	sbi->data_map.odm_group_width =
  				le32_to_cpu(dt->dt_data_map.cb_group_width);
  	sbi->data_map.odm_group_depth =
  				le32_to_cpu(dt->dt_data_map.cb_group_depth);
  	sbi->data_map.odm_mirror_cnt  =
  				le32_to_cpu(dt->dt_data_map.cb_mirror_cnt);
  	sbi->data_map.odm_raid_algorithm  =
  				le32_to_cpu(dt->dt_data_map.cb_raid_algorithm);

  /* FIXME: Only raid0 for now. if not so, do not mount */

  	if (sbi->data_map.odm_num_comps != numdevs) {
  		EXOFS_ERR("odm_num_comps(%u) != numdevs(%u)
  ",
  			  sbi->data_map.odm_num_comps, numdevs);
  		return -EINVAL;
  	}
  	if (sbi->data_map.odm_raid_algorithm != PNFS_OSD_RAID_0) {
  		EXOFS_ERR("Only RAID_0 for now
  ");
  		return -EINVAL;
  	}
  	if (0 != (numdevs % (sbi->data_map.odm_mirror_cnt + 1))) {
  		EXOFS_ERR("Data Map wrong, numdevs=%d mirrors=%d
  ",
  			  numdevs, sbi->data_map.odm_mirror_cnt);
  		return -EINVAL;
  	}

  	if (0 != (sbi->data_map.odm_stripe_unit & ~PAGE_MASK)) {
  		EXOFS_ERR("Stripe Unit(0x%llx)"
  			  " must be Multples of PAGE_SIZE(0x%lx)
  ",
  			  _LLU(sbi->data_map.odm_stripe_unit), PAGE_SIZE);
  		return -EINVAL;
  	}
  
  	sbi->layout.stripe_unit = sbi->data_map.odm_stripe_unit;
  	sbi->layout.mirrors_p1 = sbi->data_map.odm_mirror_cnt + 1;

  
  	if (sbi->data_map.odm_group_width) {
  		sbi->layout.group_width = sbi->data_map.odm_group_width;
  		sbi->layout.group_depth = sbi->data_map.odm_group_depth;
  		if (!sbi->layout.group_depth) {
  			EXOFS_ERR("group_depth == 0 && group_width != 0
  ");
  			return -EINVAL;
  		}
  		sbi->layout.group_count = sbi->data_map.odm_num_comps /
  						sbi->layout.mirrors_p1 /
  						sbi->data_map.odm_group_width;
  	} else {
  		if (sbi->data_map.odm_group_depth) {
  			printk(KERN_NOTICE "Warning: group_depth ignored "
  				"group_width == 0 && group_depth == %d
  ",
  				sbi->data_map.odm_group_depth);
  			sbi->data_map.odm_group_depth = 0;
  		}
  		sbi->layout.group_width = sbi->data_map.odm_num_comps /

  							sbi->layout.mirrors_p1;

  		sbi->layout.group_depth = -1;
  		sbi->layout.group_count = 1;
  	}
  
  	stripe_length = (u64)sbi->layout.group_width * sbi->layout.stripe_unit;
  	if (stripe_length >= (1ULL << 32)) {
  		EXOFS_ERR("Total Stripe length(0x%llx)"
  			  " >= 32bit is not supported
  ", _LLU(stripe_length));
  		return -EINVAL;
  	}

  
  	return 0;

  }

  static unsigned __ra_pages(struct exofs_layout *layout)
  {
  	const unsigned _MIN_RA = 32; /* min 128K read-ahead */
  	unsigned ra_pages = layout->group_width * layout->stripe_unit /
  				PAGE_SIZE;
  	unsigned max_io_pages = exofs_max_io_pages(layout, ~0);
  
  	ra_pages *= 2; /* two stripes */
  	if (ra_pages < _MIN_RA)
  		ra_pages = roundup(_MIN_RA, ra_pages / 2);
  
  	if (ra_pages > max_io_pages)
  		ra_pages = max_io_pages;
  
  	return ra_pages;
  }

  /* @odi is valid only as long as @fscb_dev is valid */
  static int exofs_devs_2_odi(struct exofs_dt_device_info *dt_dev,
  			     struct osd_dev_info *odi)
  {
  	odi->systemid_len = le32_to_cpu(dt_dev->systemid_len);
  	memcpy(odi->systemid, dt_dev->systemid, odi->systemid_len);
  
  	odi->osdname_len = le32_to_cpu(dt_dev->osdname_len);
  	odi->osdname = dt_dev->osdname;
  
  	/* FIXME support long names. Will need a _put function */
  	if (dt_dev->long_name_offset)
  		return -EINVAL;
  
  	/* Make sure osdname is printable!
  	 * mkexofs should give us space for a null-terminator else the
  	 * device-table is invalid.
  	 */
  	if (unlikely(odi->osdname_len >= sizeof(dt_dev->osdname)))
  		odi->osdname_len = sizeof(dt_dev->osdname) - 1;
  	dt_dev->osdname[odi->osdname_len] = 0;
  
  	/* If it's all zeros something is bad we read past end-of-obj */
  	return !(odi->systemid_len || odi->osdname_len);
  }
  
  static int exofs_read_lookup_dev_table(struct exofs_sb_info **psbi,
  				       unsigned table_count)
  {
  	struct exofs_sb_info *sbi = *psbi;
  	struct osd_dev *fscb_od;

  	struct osd_obj_id obj = {.partition = sbi->layout.s_pid,

  				 .id = EXOFS_DEVTABLE_ID};
  	struct exofs_device_table *dt;
  	unsigned table_bytes = table_count * sizeof(dt->dt_dev_table[0]) +
  					     sizeof(*dt);
  	unsigned numdevs, i;
  	int ret;
  
  	dt = kmalloc(table_bytes, GFP_KERNEL);
  	if (unlikely(!dt)) {
  		EXOFS_ERR("ERROR: allocating %x bytes for device table
  ",
  			  table_bytes);
  		return -ENOMEM;
  	}

  	fscb_od = sbi->layout.s_ods[0];
  	sbi->layout.s_ods[0] = NULL;
  	sbi->layout.s_numdevs = 0;

  	ret = exofs_read_kern(fscb_od, sbi->s_cred, &obj, 0, dt, table_bytes);
  	if (unlikely(ret)) {
  		EXOFS_ERR("ERROR: reading device table
  ");
  		goto out;
  	}
  
  	numdevs = le64_to_cpu(dt->dt_num_devices);
  	if (unlikely(!numdevs)) {
  		ret = -EINVAL;
  		goto out;
  	}
  	WARN_ON(table_count != numdevs);
  
  	ret = _read_and_match_data_map(sbi, numdevs, dt);
  	if (unlikely(ret))
  		goto out;
  
  	if (likely(numdevs > 1)) {

  		unsigned size = numdevs * sizeof(sbi->layout.s_ods[0]);

  
  		sbi = krealloc(sbi, sizeof(*sbi) + size, GFP_KERNEL);
  		if (unlikely(!sbi)) {
  			ret = -ENOMEM;
  			goto out;
  		}

  		memset(&sbi->layout.s_ods[1], 0,
  		       size - sizeof(sbi->layout.s_ods[0]));

  		*psbi = sbi;
  	}
  
  	for (i = 0; i < numdevs; i++) {
  		struct exofs_fscb fscb;
  		struct osd_dev_info odi;
  		struct osd_dev *od;
  
  		if (exofs_devs_2_odi(&dt->dt_dev_table[i], &odi)) {
  			EXOFS_ERR("ERROR: Read all-zeros device entry
  ");
  			ret = -EINVAL;
  			goto out;
  		}
  
  		printk(KERN_NOTICE "Add device[%d]: osd_name-%s
  ",
  		       i, odi.osdname);
  
  		/* On all devices the device table is identical. The user can
  		 * specify any one of the participating devices on the command
  		 * line. We always keep them in device-table order.
  		 */
  		if (fscb_od && osduld_device_same(fscb_od, &odi)) {

  			sbi->layout.s_ods[i] = fscb_od;
  			++sbi->layout.s_numdevs;

  			fscb_od = NULL;
  			continue;
  		}
  
  		od = osduld_info_lookup(&odi);

  		if (IS_ERR(od)) {

  			ret = PTR_ERR(od);
  			EXOFS_ERR("ERROR: device requested is not found "
  				  "osd_name-%s =>%d
  ", odi.osdname, ret);
  			goto out;
  		}

  		sbi->layout.s_ods[i] = od;
  		++sbi->layout.s_numdevs;

  
  		/* Read the fscb of the other devices to make sure the FS
  		 * partition is there.
  		 */
  		ret = exofs_read_kern(od, sbi->s_cred, &obj, 0, &fscb,
  				      sizeof(fscb));
  		if (unlikely(ret)) {
  			EXOFS_ERR("ERROR: Malformed participating device "
  				  "error reading fscb osd_name-%s
  ",
  				  odi.osdname);
  			goto out;
  		}
  
  		/* TODO: verify other information is correct and FS-uuid
  		 *	 matches. Benny what did you say about device table
  		 *	 generation and old devices?
  		 */
  	}
  
  out:
  	kfree(dt);
  	if (unlikely(!ret && fscb_od)) {
  		EXOFS_ERR(
  		      "ERROR: Bad device-table container device not present
  ");
  		osduld_put_device(fscb_od);
  		ret = -EINVAL;
  	}
  
  	return ret;
  }

  /*
   * Read the superblock from the OSD and fill in the fields
   */
  static int exofs_fill_super(struct super_block *sb, void *data, int silent)
  {
  	struct inode *root;
  	struct exofs_mountopt *opts = data;
  	struct exofs_sb_info *sbi;	/*extended info                  */

  	struct osd_dev *od;		/* Master device                 */

  	struct exofs_fscb fscb;		/*on-disk superblock info        */

  	struct osd_obj_id obj;

  	unsigned table_count;

  	int ret;
  
  	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
  	if (!sbi)
  		return -ENOMEM;

  	ret = bdi_setup_and_register(&sbi->bdi, "exofs", BDI_CAP_MAP_COPY);
  	if (ret)
  		goto free_bdi;

  	/* use mount options to fill superblock */

  	if (opts->is_osdname) {
  		struct osd_dev_info odi = {.systemid_len = 0};
  
  		odi.osdname_len = strlen(opts->dev_name);
  		odi.osdname = (u8 *)opts->dev_name;
  		od = osduld_info_lookup(&odi);
  	} else {
  		od = osduld_path_lookup(opts->dev_name);
  	}

  	if (IS_ERR(od)) {

  		ret = -EINVAL;

  		goto free_sbi;
  	}

  	/* Default layout in case we do not have a device-table */

  	sbi->layout.stripe_unit = PAGE_SIZE;
  	sbi->layout.mirrors_p1 = 1;
  	sbi->layout.group_width = 1;

  	sbi->layout.group_depth = -1;
  	sbi->layout.group_count = 1;

  	sbi->layout.s_ods[0] = od;
  	sbi->layout.s_numdevs = 1;
  	sbi->layout.s_pid = opts->pid;

  	sbi->s_timeout = opts->timeout;
  
  	/* fill in some other data by hand */
  	memset(sb->s_id, 0, sizeof(sb->s_id));
  	strcpy(sb->s_id, "exofs");
  	sb->s_blocksize = EXOFS_BLKSIZE;
  	sb->s_blocksize_bits = EXOFS_BLKSHIFT;
  	sb->s_maxbytes = MAX_LFS_FILESIZE;
  	atomic_set(&sbi->s_curr_pending, 0);
  	sb->s_bdev = NULL;
  	sb->s_dev = 0;

  	obj.partition = sbi->layout.s_pid;

  	obj.id = EXOFS_SUPER_ID;
  	exofs_make_credential(sbi->s_cred, &obj);

  	ret = exofs_read_kern(od, sbi->s_cred, &obj, 0, &fscb, sizeof(fscb));
  	if (unlikely(ret))

  		goto free_sbi;

  
  	sb->s_magic = le16_to_cpu(fscb.s_magic);

  	/* NOTE: we read below to be backward compatible with old versions */

  	sbi->s_nextid = le64_to_cpu(fscb.s_nextid);
  	sbi->s_numfiles = le32_to_cpu(fscb.s_numfiles);
  
  	/* make sure what we read from the object store is correct */
  	if (sb->s_magic != EXOFS_SUPER_MAGIC) {
  		if (!silent)
  			EXOFS_ERR("ERROR: Bad magic value
  ");
  		ret = -EINVAL;
  		goto free_sbi;
  	}

  	if (le32_to_cpu(fscb.s_version) > EXOFS_FSCB_VER) {

  		EXOFS_ERR("ERROR: Bad FSCB version expected-%d got-%d
  ",
  			  EXOFS_FSCB_VER, le32_to_cpu(fscb.s_version));
  		ret = -EINVAL;
  		goto free_sbi;
  	}

  
  	/* start generation numbers from a random point */
  	get_random_bytes(&sbi->s_next_generation, sizeof(u32));
  	spin_lock_init(&sbi->s_next_gen_lock);

  	table_count = le64_to_cpu(fscb.s_dev_table_count);
  	if (table_count) {
  		ret = exofs_read_lookup_dev_table(&sbi, table_count);
  		if (unlikely(ret))
  			goto free_sbi;
  	}

  	__sbi_read_stats(sbi);

  	/* set up operation vectors */

  	sbi->bdi.ra_pages = __ra_pages(&sbi->layout);

  	sb->s_bdi = &sbi->bdi;

  	sb->s_fs_info = sbi;

  	sb->s_op = &exofs_sops;

  	sb->s_export_op = &exofs_export_ops;

  	root = exofs_iget(sb, EXOFS_ROOT_ID - EXOFS_OBJ_OFF);
  	if (IS_ERR(root)) {
  		EXOFS_ERR("ERROR: exofs_iget failed
  ");
  		ret = PTR_ERR(root);
  		goto free_sbi;
  	}
  	sb->s_root = d_alloc_root(root);
  	if (!sb->s_root) {
  		iput(root);
  		EXOFS_ERR("ERROR: get root inode failed
  ");
  		ret = -ENOMEM;
  		goto free_sbi;
  	}
  
  	if (!S_ISDIR(root->i_mode)) {
  		dput(sb->s_root);
  		sb->s_root = NULL;
  		EXOFS_ERR("ERROR: corrupt root inode (mode = %hd)
  ",
  		       root->i_mode);
  		ret = -EINVAL;
  		goto free_sbi;
  	}

  	_exofs_print_device("Mounting", opts->dev_name, sbi->layout.s_ods[0],
  			    sbi->layout.s_pid);

  	if (opts->is_osdname)
  		kfree(opts->dev_name);

  	return 0;

  
  free_sbi:

  	bdi_destroy(&sbi->bdi);
  free_bdi:

  	EXOFS_ERR("Unable to mount exofs on %s pid=0x%llx err=%d
  ",

  		  opts->dev_name, sbi->layout.s_pid, ret);

  	exofs_free_sbi(sbi);

  	if (opts->is_osdname)
  		kfree(opts->dev_name);

  	return ret;

  }
  
  /*
   * Set up the superblock (calls exofs_fill_super eventually)
   */

  static struct dentry *exofs_mount(struct file_system_type *type,

  			  int flags, const char *dev_name,

  			  void *data)

  {
  	struct exofs_mountopt opts;
  	int ret;
  
  	ret = parse_options(data, &opts);
  	if (ret)

  		return ERR_PTR(ret);

  	if (!opts.dev_name)
  		opts.dev_name = dev_name;

  	return mount_nodev(type, flags, &opts, exofs_fill_super);

  }
  
  /*
   * Return information about the file system state in the buffer.  This is used
   * by the 'df' command, for example.
   */
  static int exofs_statfs(struct dentry *dentry, struct kstatfs *buf)
  {
  	struct super_block *sb = dentry->d_sb;
  	struct exofs_sb_info *sbi = sb->s_fs_info;

  	struct exofs_io_state *ios;

  	struct osd_attr attrs[] = {
  		ATTR_DEF(OSD_APAGE_PARTITION_QUOTAS,
  			OSD_ATTR_PQ_CAPACITY_QUOTA, sizeof(__be64)),
  		ATTR_DEF(OSD_APAGE_PARTITION_INFORMATION,
  			OSD_ATTR_PI_USED_CAPACITY, sizeof(__be64)),
  	};
  	uint64_t capacity = ULLONG_MAX;
  	uint64_t used = ULLONG_MAX;

  	uint8_t cred_a[OSD_CAP_LEN];
  	int ret;

  	ret = exofs_get_io_state(&sbi->layout, &ios);

  	if (ret) {
  		EXOFS_DBGMSG("exofs_get_io_state failed.
  ");
  		return ret;

  	}

  	exofs_make_credential(cred_a, &ios->obj);
  	ios->cred = sbi->s_cred;
  	ios->in_attr = attrs;
  	ios->in_attr_len = ARRAY_SIZE(attrs);
  
  	ret = exofs_sbi_read(ios);

  	if (unlikely(ret))
  		goto out;

  	ret = extract_attr_from_ios(ios, &attrs[0]);

  	if (likely(!ret)) {

  		capacity = get_unaligned_be64(attrs[0].val_ptr);

  		if (unlikely(!capacity))
  			capacity = ULLONG_MAX;
  	} else

  		EXOFS_DBGMSG("exofs_statfs: get capacity failed.
  ");

  	ret = extract_attr_from_ios(ios, &attrs[1]);

  	if (likely(!ret))
  		used = get_unaligned_be64(attrs[1].val_ptr);
  	else
  		EXOFS_DBGMSG("exofs_statfs: get used-space failed.
  ");
  
  	/* fill in the stats buffer */
  	buf->f_type = EXOFS_SUPER_MAGIC;
  	buf->f_bsize = EXOFS_BLKSIZE;

  	buf->f_blocks = capacity >> 9;
  	buf->f_bfree = (capacity - used) >> 9;

  	buf->f_bavail = buf->f_bfree;
  	buf->f_files = sbi->s_numfiles;
  	buf->f_ffree = EXOFS_MAX_ID - sbi->s_numfiles;
  	buf->f_namelen = EXOFS_NAME_LEN;
  
  out:

  	exofs_put_io_state(ios);

  	return ret;
  }
  
  static const struct super_operations exofs_sops = {
  	.alloc_inode    = exofs_alloc_inode,
  	.destroy_inode  = exofs_destroy_inode,
  	.write_inode    = exofs_write_inode,

  	.evict_inode    = exofs_evict_inode,

  	.put_super      = exofs_put_super,
  	.write_super    = exofs_write_super,

  	.sync_fs	= exofs_sync_fs,

  	.statfs         = exofs_statfs,
  };
  
  /******************************************************************************

   * EXPORT OPERATIONS
   *****************************************************************************/
  
  struct dentry *exofs_get_parent(struct dentry *child)
  {
  	unsigned long ino = exofs_parent_ino(child);
  
  	if (!ino)
  		return NULL;
  
  	return d_obtain_alias(exofs_iget(child->d_inode->i_sb, ino));
  }
  
  static struct inode *exofs_nfs_get_inode(struct super_block *sb,
  		u64 ino, u32 generation)
  {
  	struct inode *inode;
  
  	inode = exofs_iget(sb, ino);
  	if (IS_ERR(inode))
  		return ERR_CAST(inode);
  	if (generation && inode->i_generation != generation) {
  		/* we didn't find the right inode.. */
  		iput(inode);
  		return ERR_PTR(-ESTALE);
  	}
  	return inode;
  }
  
  static struct dentry *exofs_fh_to_dentry(struct super_block *sb,
  				struct fid *fid, int fh_len, int fh_type)
  {
  	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
  				    exofs_nfs_get_inode);
  }
  
  static struct dentry *exofs_fh_to_parent(struct super_block *sb,
  				struct fid *fid, int fh_len, int fh_type)
  {
  	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
  				    exofs_nfs_get_inode);
  }
  
  static const struct export_operations exofs_export_ops = {
  	.fh_to_dentry = exofs_fh_to_dentry,
  	.fh_to_parent = exofs_fh_to_parent,
  	.get_parent = exofs_get_parent,
  };
  
  /******************************************************************************

   * INSMOD/RMMOD
   *****************************************************************************/
  
  /*
   * struct that describes this file system
   */
  static struct file_system_type exofs_type = {
  	.owner          = THIS_MODULE,
  	.name           = "exofs",

  	.mount          = exofs_mount,

  	.kill_sb        = generic_shutdown_super,
  };
  
  static int __init init_exofs(void)
  {
  	int err;
  
  	err = init_inodecache();
  	if (err)
  		goto out;
  
  	err = register_filesystem(&exofs_type);
  	if (err)
  		goto out_d;
  
  	return 0;
  out_d:
  	destroy_inodecache();
  out:
  	return err;
  }
  
  static void __exit exit_exofs(void)
  {
  	unregister_filesystem(&exofs_type);
  	destroy_inodecache();
  }
  
  MODULE_AUTHOR("Avishay Traeger <avishay@gmail.com>");
  MODULE_DESCRIPTION("exofs");
  MODULE_LICENSE("GPL");
  
  module_init(init_exofs)
  module_exit(exit_exofs)