/*
   * hugetlbpage-backed filesystem.  Based on ramfs.
   *
   * William Irwin, 2002
   *
   * Copyright (C) 2002 Linus Torvalds.
   */
  
  #include <linux/module.h>
  #include <linux/thread_info.h>
  #include <asm/current.h>
  #include <linux/sched.h>		/* remove ASAP */
  #include <linux/fs.h>
  #include <linux/mount.h>
  #include <linux/file.h>

  #include <linux/kernel.h>

  #include <linux/writeback.h>
  #include <linux/pagemap.h>
  #include <linux/highmem.h>
  #include <linux/init.h>
  #include <linux/string.h>

  #include <linux/capability.h>

  #include <linux/ctype.h>

  #include <linux/backing-dev.h>
  #include <linux/hugetlb.h>
  #include <linux/pagevec.h>

  #include <linux/parser.h>

  #include <linux/mman.h>

  #include <linux/slab.h>
  #include <linux/dnotify.h>
  #include <linux/statfs.h>
  #include <linux/security.h>

  #include <linux/magic.h>

  #include <linux/migrate.h>

  
  #include <asm/uaccess.h>

  static const struct super_operations hugetlbfs_ops;

  static const struct address_space_operations hugetlbfs_aops;

  const struct file_operations hugetlbfs_file_operations;

  static const struct inode_operations hugetlbfs_dir_inode_operations;
  static const struct inode_operations hugetlbfs_inode_operations;

  
  static struct backing_dev_info hugetlbfs_backing_dev_info = {

  	.name		= "hugetlbfs",

  	.ra_pages	= 0,	/* No readahead */

  	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,

  };
  
  int sysctl_hugetlb_shm_group;

  enum {
  	Opt_size, Opt_nr_inodes,
  	Opt_mode, Opt_uid, Opt_gid,

  	Opt_pagesize,

  	Opt_err,
  };

  static const match_table_t tokens = {

  	{Opt_size,	"size=%s"},
  	{Opt_nr_inodes,	"nr_inodes=%s"},
  	{Opt_mode,	"mode=%o"},
  	{Opt_uid,	"uid=%u"},
  	{Opt_gid,	"gid=%u"},

  	{Opt_pagesize,	"pagesize=%s"},

  	{Opt_err,	NULL},
  };

  static void huge_pagevec_release(struct pagevec *pvec)
  {
  	int i;
  
  	for (i = 0; i < pagevec_count(pvec); ++i)
  		put_page(pvec->pages[i]);
  
  	pagevec_reinit(pvec);
  }

  static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
  {

  	struct inode *inode = file->f_path.dentry->d_inode;

  	loff_t len, vma_len;
  	int ret;

  	struct hstate *h = hstate_file(file);

  	/*

  	 * vma address alignment (but not the pgoff alignment) has
  	 * already been checked by prepare_hugepage_range.  If you add
  	 * any error returns here, do so after setting VM_HUGETLB, so
  	 * is_vm_hugetlb_page tests below unmap_region go the right
  	 * way when do_mmap_pgoff unwinds (may be important on powerpc
  	 * and ia64).

  	 */
  	vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
  	vma->vm_ops = &hugetlb_vm_ops;

  	if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))

  		return -EINVAL;

  	vma_len = (loff_t)(vma->vm_end - vma->vm_start);

  	mutex_lock(&inode->i_mutex);

  	file_accessed(file);

  
  	ret = -ENOMEM;
  	len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);

  	if (hugetlb_reserve_pages(inode,

  				vma->vm_pgoff >> huge_page_order(h),

  				len >> huge_page_shift(h), vma,
  				vma->vm_flags))

  		goto out;

  	ret = 0;
  	hugetlb_prefault_arch_hook(vma->vm_mm);

  	if (vma->vm_flags & VM_WRITE && inode->i_size < len)

  		inode->i_size = len;
  out:

  	mutex_unlock(&inode->i_mutex);

  
  	return ret;
  }
  
  /*

   * Called under down_write(mmap_sem).

   */

  #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA

  static unsigned long
  hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
  		unsigned long len, unsigned long pgoff, unsigned long flags)
  {
  	struct mm_struct *mm = current->mm;
  	struct vm_area_struct *vma;
  	unsigned long start_addr;

  	struct hstate *h = hstate_file(file);

  	if (len & ~huge_page_mask(h))

  		return -EINVAL;
  	if (len > TASK_SIZE)
  		return -ENOMEM;

  	if (flags & MAP_FIXED) {

  		if (prepare_hugepage_range(file, addr, len))

  			return -EINVAL;
  		return addr;
  	}

  	if (addr) {

  		addr = ALIGN(addr, huge_page_size(h));

  		vma = find_vma(mm, addr);
  		if (TASK_SIZE - len >= addr &&
  		    (!vma || addr + len <= vma->vm_start))
  			return addr;
  	}
  
  	start_addr = mm->free_area_cache;

  	if (len <= mm->cached_hole_size)
  		start_addr = TASK_UNMAPPED_BASE;

  full_search:

  	addr = ALIGN(start_addr, huge_page_size(h));

  
  	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
  		/* At this point:  (!vma || addr < vma->vm_end). */
  		if (TASK_SIZE - len < addr) {
  			/*
  			 * Start a new search - just in case we missed
  			 * some holes.
  			 */
  			if (start_addr != TASK_UNMAPPED_BASE) {
  				start_addr = TASK_UNMAPPED_BASE;
  				goto full_search;
  			}
  			return -ENOMEM;
  		}
  
  		if (!vma || addr + len <= vma->vm_start)
  			return addr;

  		addr = ALIGN(vma->vm_end, huge_page_size(h));

  	}
  }
  #endif

  static int
  hugetlbfs_read_actor(struct page *page, unsigned long offset,
  			char __user *buf, unsigned long count,
  			unsigned long size)
  {
  	char *kaddr;
  	unsigned long left, copied = 0;
  	int i, chunksize;
  
  	if (size > count)
  		size = count;
  
  	/* Find which 4k chunk and offset with in that chunk */
  	i = offset >> PAGE_CACHE_SHIFT;
  	offset = offset & ~PAGE_CACHE_MASK;
  
  	while (size) {
  		chunksize = PAGE_CACHE_SIZE;
  		if (offset)
  			chunksize -= offset;
  		if (chunksize > size)
  			chunksize = size;
  		kaddr = kmap(&page[i]);
  		left = __copy_to_user(buf, kaddr + offset, chunksize);
  		kunmap(&page[i]);
  		if (left) {
  			copied += (chunksize - left);
  			break;
  		}
  		offset = 0;
  		size -= chunksize;
  		buf += chunksize;
  		copied += chunksize;
  		i++;
  	}
  	return copied ? copied : -EFAULT;
  }
  
  /*
   * Support for read() - Find the page attached to f_mapping and copy out the
   * data. Its *very* similar to do_generic_mapping_read(), we can't use that
   * since it has PAGE_CACHE_SIZE assumptions.
   */
  static ssize_t hugetlbfs_read(struct file *filp, char __user *buf,
  			      size_t len, loff_t *ppos)
  {

  	struct hstate *h = hstate_file(filp);

  	struct address_space *mapping = filp->f_mapping;
  	struct inode *inode = mapping->host;

  	unsigned long index = *ppos >> huge_page_shift(h);
  	unsigned long offset = *ppos & ~huge_page_mask(h);

  	unsigned long end_index;
  	loff_t isize;
  	ssize_t retval = 0;
  
  	mutex_lock(&inode->i_mutex);
  
  	/* validate length */
  	if (len == 0)
  		goto out;
  
  	isize = i_size_read(inode);
  	if (!isize)
  		goto out;

  	end_index = (isize - 1) >> huge_page_shift(h);

  	for (;;) {
  		struct page *page;

  		unsigned long nr, ret;

  		int ra;

  
  		/* nr is the maximum number of bytes to copy from this page */

  		nr = huge_page_size(h);

  		if (index >= end_index) {
  			if (index > end_index)
  				goto out;

  			nr = ((isize - 1) & ~huge_page_mask(h)) + 1;

  			if (nr <= offset) {
  				goto out;
  			}
  		}
  		nr = nr - offset;
  
  		/* Find the page */
  		page = find_get_page(mapping, index);
  		if (unlikely(page == NULL)) {
  			/*
  			 * We have a HOLE, zero out the user-buffer for the
  			 * length of the hole or request.
  			 */
  			ret = len < nr ? len : nr;
  			if (clear_user(buf, ret))

  				ra = -EFAULT;
  			else
  				ra = 0;

  		} else {
  			/*
  			 * We have the page, copy it to user space buffer.
  			 */

  			ra = hugetlbfs_read_actor(page, offset, buf, len, nr);
  			ret = ra;

  		}

  		if (ra < 0) {

  			if (retval == 0)

  				retval = ra;

  			if (page)
  				page_cache_release(page);
  			goto out;
  		}
  
  		offset += ret;
  		retval += ret;
  		len -= ret;

  		index += offset >> huge_page_shift(h);
  		offset &= ~huge_page_mask(h);

  
  		if (page)
  			page_cache_release(page);
  
  		/* short read or no more work */
  		if ((ret != nr) || (len == 0))
  			break;
  	}
  out:

  	*ppos = ((loff_t)index << huge_page_shift(h)) + offset;

  	mutex_unlock(&inode->i_mutex);
  	return retval;
  }

  static int hugetlbfs_write_begin(struct file *file,
  			struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata)

  {
  	return -EINVAL;
  }

  static int hugetlbfs_write_end(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *page, void *fsdata)

  {

  	BUG();

  	return -EINVAL;
  }

  static void truncate_huge_page(struct page *page)
  {

  	cancel_dirty_page(page, /* No IO accounting for huge pages? */0);

  	ClearPageUptodate(page);

  	delete_from_page_cache(page);

  }

  static void truncate_hugepages(struct inode *inode, loff_t lstart)

  {

  	struct hstate *h = hstate_inode(inode);

  	struct address_space *mapping = &inode->i_data;

  	const pgoff_t start = lstart >> huge_page_shift(h);

  	struct pagevec pvec;
  	pgoff_t next;

  	int i, freed = 0;

  
  	pagevec_init(&pvec, 0);
  	next = start;
  	while (1) {
  		if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
  			if (next == start)
  				break;
  			next = start;
  			continue;
  		}
  
  		for (i = 0; i < pagevec_count(&pvec); ++i) {
  			struct page *page = pvec.pages[i];
  
  			lock_page(page);
  			if (page->index > next)
  				next = page->index;
  			++next;
  			truncate_huge_page(page);
  			unlock_page(page);

  			freed++;

  		}
  		huge_pagevec_release(&pvec);
  	}
  	BUG_ON(!lstart && mapping->nrpages);

  	hugetlb_unreserve_pages(inode, start, freed);

  }

  static void hugetlbfs_evict_inode(struct inode *inode)

  {

  	truncate_hugepages(inode, 0);

  	end_writeback(inode);

  }

  static inline void

  hugetlb_vmtruncate_list(struct prio_tree_root *root, pgoff_t pgoff)

  {
  	struct vm_area_struct *vma;
  	struct prio_tree_iter iter;

  	vma_prio_tree_foreach(vma, &iter, root, pgoff, ULONG_MAX) {

  		unsigned long v_offset;

  		/*

  		 * Can the expression below overflow on 32-bit arches?
  		 * No, because the prio_tree returns us only those vmas
  		 * which overlap the truncated area starting at pgoff,
  		 * and no vma on a 32-bit arch can span beyond the 4GB.

  		 */

  		if (vma->vm_pgoff < pgoff)
  			v_offset = (pgoff - vma->vm_pgoff) << PAGE_SHIFT;
  		else

  			v_offset = 0;

  		__unmap_hugepage_range(vma,

  				vma->vm_start + v_offset, vma->vm_end, NULL);

  	}
  }

  static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
  {

  	pgoff_t pgoff;

  	struct address_space *mapping = inode->i_mapping;

  	struct hstate *h = hstate_inode(inode);

  	BUG_ON(offset & ~huge_page_mask(h));

  	pgoff = offset >> PAGE_SHIFT;

  	i_size_write(inode, offset);

  	mutex_lock(&mapping->i_mmap_mutex);

  	if (!prio_tree_empty(&mapping->i_mmap))
  		hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);

  	mutex_unlock(&mapping->i_mmap_mutex);

  	truncate_hugepages(inode, offset);

  	return 0;
  }
  
  static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	struct inode *inode = dentry->d_inode;

  	struct hstate *h = hstate_inode(inode);

  	int error;
  	unsigned int ia_valid = attr->ia_valid;
  
  	BUG_ON(!inode);
  
  	error = inode_change_ok(inode, attr);
  	if (error)

  		return error;

  
  	if (ia_valid & ATTR_SIZE) {
  		error = -EINVAL;

  		if (attr->ia_size & ~huge_page_mask(h))
  			return -EINVAL;
  		error = hugetlb_vmtruncate(inode, attr->ia_size);

  		if (error)

  			return error;

  	}

  
  	setattr_copy(inode, attr);
  	mark_inode_dirty(inode);
  	return 0;

  }
  
  static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid, 
  					gid_t gid, int mode, dev_t dev)
  {
  	struct inode *inode;

  
  	inode = new_inode(sb);
  	if (inode) {
  		struct hugetlbfs_inode_info *info;

  		inode->i_ino = get_next_ino();

  		inode->i_mode = mode;
  		inode->i_uid = uid;
  		inode->i_gid = gid;

  		inode->i_mapping->a_ops = &hugetlbfs_aops;
  		inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
  		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;

  		INIT_LIST_HEAD(&inode->i_mapping->private_list);

  		info = HUGETLBFS_I(inode);

  		/*
  		 * The policy is initialized here even if we are creating a
  		 * private inode because initialization simply creates an
  		 * an empty rb tree and calls spin_lock_init(), later when we
  		 * call mpol_free_shared_policy() it will just return because
  		 * the rb tree will still be empty.
  		 */

  		mpol_shared_policy_init(&info->policy, NULL);

  		switch (mode & S_IFMT) {
  		default:
  			init_special_inode(inode, mode, dev);
  			break;
  		case S_IFREG:
  			inode->i_op = &hugetlbfs_inode_operations;
  			inode->i_fop = &hugetlbfs_file_operations;
  			break;
  		case S_IFDIR:
  			inode->i_op = &hugetlbfs_dir_inode_operations;
  			inode->i_fop = &simple_dir_operations;
  
  			/* directory inodes start off with i_nlink == 2 (for "." entry) */

  			inc_nlink(inode);

  			break;
  		case S_IFLNK:
  			inode->i_op = &page_symlink_inode_operations;
  			break;
  		}

  		lockdep_annotate_inode_mutex_key(inode);

  	}
  	return inode;
  }
  
  /*
   * File creation. Allocate an inode, and we're done..
   */
  static int hugetlbfs_mknod(struct inode *dir,
  			struct dentry *dentry, int mode, dev_t dev)
  {
  	struct inode *inode;
  	int error = -ENOSPC;
  	gid_t gid;
  
  	if (dir->i_mode & S_ISGID) {
  		gid = dir->i_gid;
  		if (S_ISDIR(mode))
  			mode |= S_ISGID;
  	} else {

  		gid = current_fsgid();

  	}

  	inode = hugetlbfs_get_inode(dir->i_sb, current_fsuid(), gid, mode, dev);

  	if (inode) {
  		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
  		d_instantiate(dentry, inode);
  		dget(dentry);	/* Extra count - pin the dentry in core */
  		error = 0;
  	}
  	return error;
  }
  
  static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
  {
  	int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
  	if (!retval)

  		inc_nlink(dir);

  	return retval;
  }
  
  static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
  {
  	return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
  }
  
  static int hugetlbfs_symlink(struct inode *dir,
  			struct dentry *dentry, const char *symname)
  {
  	struct inode *inode;
  	int error = -ENOSPC;
  	gid_t gid;
  
  	if (dir->i_mode & S_ISGID)
  		gid = dir->i_gid;
  	else

  		gid = current_fsgid();

  	inode = hugetlbfs_get_inode(dir->i_sb, current_fsuid(),

  					gid, S_IFLNK|S_IRWXUGO, 0);
  	if (inode) {
  		int l = strlen(symname)+1;
  		error = page_symlink(inode, symname, l);
  		if (!error) {
  			d_instantiate(dentry, inode);
  			dget(dentry);
  		} else
  			iput(inode);
  	}
  	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
  
  	return error;
  }
  
  /*

   * mark the head page dirty

   */
  static int hugetlbfs_set_page_dirty(struct page *page)
  {

  	struct page *head = compound_head(page);

  
  	SetPageDirty(head);

  	return 0;
  }

  static int hugetlbfs_migrate_page(struct address_space *mapping,
  				struct page *newpage, struct page *page)
  {
  	int rc;
  
  	rc = migrate_huge_page_move_mapping(mapping, newpage, page);
  	if (rc)
  		return rc;
  	migrate_page_copy(newpage, page);
  
  	return 0;
  }

  static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)

  {

  	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);

  	struct hstate *h = hstate_inode(dentry->d_inode);

  
  	buf->f_type = HUGETLBFS_MAGIC;

  	buf->f_bsize = huge_page_size(h);

  	if (sbinfo) {
  		spin_lock(&sbinfo->stat_lock);

  		/* If no limits set, just report 0 for max/free/used
  		 * blocks, like simple_statfs() */
  		if (sbinfo->max_blocks >= 0) {
  			buf->f_blocks = sbinfo->max_blocks;
  			buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
  			buf->f_files = sbinfo->max_inodes;
  			buf->f_ffree = sbinfo->free_inodes;
  		}

  		spin_unlock(&sbinfo->stat_lock);
  	}
  	buf->f_namelen = NAME_MAX;
  	return 0;
  }
  
  static void hugetlbfs_put_super(struct super_block *sb)
  {
  	struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
  
  	if (sbi) {
  		sb->s_fs_info = NULL;
  		kfree(sbi);
  	}
  }

  static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
  {
  	if (sbinfo->free_inodes >= 0) {
  		spin_lock(&sbinfo->stat_lock);
  		if (unlikely(!sbinfo->free_inodes)) {
  			spin_unlock(&sbinfo->stat_lock);
  			return 0;
  		}
  		sbinfo->free_inodes--;
  		spin_unlock(&sbinfo->stat_lock);
  	}
  
  	return 1;
  }
  
  static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
  {
  	if (sbinfo->free_inodes >= 0) {
  		spin_lock(&sbinfo->stat_lock);
  		sbinfo->free_inodes++;
  		spin_unlock(&sbinfo->stat_lock);
  	}
  }

  static struct kmem_cache *hugetlbfs_inode_cachep;

  
  static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
  {

  	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);

  	struct hugetlbfs_inode_info *p;

  	if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
  		return NULL;

  	p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);

  	if (unlikely(!p)) {
  		hugetlbfs_inc_free_inodes(sbinfo);

  		return NULL;

  	}

  	return &p->vfs_inode;
  }

  static void hugetlbfs_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(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
  }

  static void hugetlbfs_destroy_inode(struct inode *inode)
  {

  	hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));

  	mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);

  	call_rcu(&inode->i_rcu, hugetlbfs_i_callback);

  }

  static const struct address_space_operations hugetlbfs_aops = {

  	.write_begin	= hugetlbfs_write_begin,
  	.write_end	= hugetlbfs_write_end,

  	.set_page_dirty	= hugetlbfs_set_page_dirty,

  	.migratepage    = hugetlbfs_migrate_page,

  };

  static void init_once(void *foo)

  {
  	struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;

  	inode_init_once(&ei->vfs_inode);

  }

  const struct file_operations hugetlbfs_file_operations = {

  	.read			= hugetlbfs_read,

  	.mmap			= hugetlbfs_file_mmap,

  	.fsync			= noop_fsync,

  	.get_unmapped_area	= hugetlb_get_unmapped_area,

  	.llseek		= default_llseek,

  };

  static const struct inode_operations hugetlbfs_dir_inode_operations = {

  	.create		= hugetlbfs_create,
  	.lookup		= simple_lookup,
  	.link		= simple_link,
  	.unlink		= simple_unlink,
  	.symlink	= hugetlbfs_symlink,
  	.mkdir		= hugetlbfs_mkdir,
  	.rmdir		= simple_rmdir,
  	.mknod		= hugetlbfs_mknod,
  	.rename		= simple_rename,
  	.setattr	= hugetlbfs_setattr,
  };

  static const struct inode_operations hugetlbfs_inode_operations = {

  	.setattr	= hugetlbfs_setattr,
  };

  static const struct super_operations hugetlbfs_ops = {

  	.alloc_inode    = hugetlbfs_alloc_inode,
  	.destroy_inode  = hugetlbfs_destroy_inode,

  	.evict_inode	= hugetlbfs_evict_inode,

  	.statfs		= hugetlbfs_statfs,

  	.put_super	= hugetlbfs_put_super,

  	.show_options	= generic_show_options,

  };
  
  static int
  hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
  {

  	char *p, *rest;
  	substring_t args[MAX_OPT_ARGS];
  	int option;

  	unsigned long long size = 0;
  	enum { NO_SIZE, SIZE_STD, SIZE_PERCENT } setsize = NO_SIZE;

  
  	if (!options)
  		return 0;

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

  		if (!*p)
  			continue;

  
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case Opt_uid:
  			if (match_int(&args[0], &option))
   				goto bad_val;
  			pconfig->uid = option;
  			break;
  
  		case Opt_gid:
  			if (match_int(&args[0], &option))
   				goto bad_val;
  			pconfig->gid = option;
  			break;
  
  		case Opt_mode:
  			if (match_octal(&args[0], &option))
   				goto bad_val;

  			pconfig->mode = option & 01777U;

  			break;
  
  		case Opt_size: {

  			/* memparse() will accept a K/M/G without a digit */
  			if (!isdigit(*args[0].from))
  				goto bad_val;
  			size = memparse(args[0].from, &rest);

  			setsize = SIZE_STD;
  			if (*rest == '%')
  				setsize = SIZE_PERCENT;

  			break;
  		}

  		case Opt_nr_inodes:
  			/* memparse() will accept a K/M/G without a digit */
  			if (!isdigit(*args[0].from))
  				goto bad_val;
  			pconfig->nr_inodes = memparse(args[0].from, &rest);
  			break;

  		case Opt_pagesize: {
  			unsigned long ps;
  			ps = memparse(args[0].from, &rest);
  			pconfig->hstate = size_to_hstate(ps);
  			if (!pconfig->hstate) {
  				printk(KERN_ERR
  				"hugetlbfs: Unsupported page size %lu MB
  ",
  					ps >> 20);
  				return -EINVAL;
  			}
  			break;
  		}

  		default:

  			printk(KERN_ERR "hugetlbfs: Bad mount option: \"%s\"
  ",
  				 p);
  			return -EINVAL;

  			break;
  		}

  	}

  
  	/* Do size after hstate is set up */
  	if (setsize > NO_SIZE) {
  		struct hstate *h = pconfig->hstate;
  		if (setsize == SIZE_PERCENT) {
  			size <<= huge_page_shift(h);
  			size *= h->max_huge_pages;
  			do_div(size, 100);
  		}
  		pconfig->nr_blocks = (size >> huge_page_shift(h));
  	}

  	return 0;

  
  bad_val:
   	printk(KERN_ERR "hugetlbfs: Bad value '%s' for mount option '%s'
  ",
  	       args[0].from, p);

   	return -EINVAL;

  }
  
  static int
  hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
  {
  	struct inode * inode;
  	struct dentry * root;
  	int ret;
  	struct hugetlbfs_config config;
  	struct hugetlbfs_sb_info *sbinfo;

  	save_mount_options(sb, data);

  	config.nr_blocks = -1; /* No limit on size by default */
  	config.nr_inodes = -1; /* No limit on number of inodes by default */

  	config.uid = current_fsuid();
  	config.gid = current_fsgid();

  	config.mode = 0755;

  	config.hstate = &default_hstate;

  	ret = hugetlbfs_parse_options(data, &config);

  	if (ret)
  		return ret;
  
  	sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
  	if (!sbinfo)
  		return -ENOMEM;
  	sb->s_fs_info = sbinfo;

  	sbinfo->hstate = config.hstate;

  	spin_lock_init(&sbinfo->stat_lock);
  	sbinfo->max_blocks = config.nr_blocks;
  	sbinfo->free_blocks = config.nr_blocks;
  	sbinfo->max_inodes = config.nr_inodes;
  	sbinfo->free_inodes = config.nr_inodes;
  	sb->s_maxbytes = MAX_LFS_FILESIZE;

  	sb->s_blocksize = huge_page_size(config.hstate);
  	sb->s_blocksize_bits = huge_page_shift(config.hstate);

  	sb->s_magic = HUGETLBFS_MAGIC;
  	sb->s_op = &hugetlbfs_ops;
  	sb->s_time_gran = 1;
  	inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
  					S_IFDIR | config.mode, 0);
  	if (!inode)
  		goto out_free;
  
  	root = d_alloc_root(inode);
  	if (!root) {
  		iput(inode);
  		goto out_free;
  	}
  	sb->s_root = root;
  	return 0;
  out_free:
  	kfree(sbinfo);
  	return -ENOMEM;
  }

  int hugetlb_get_quota(struct address_space *mapping, long delta)

  {
  	int ret = 0;
  	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
  
  	if (sbinfo->free_blocks > -1) {
  		spin_lock(&sbinfo->stat_lock);

  		if (sbinfo->free_blocks - delta >= 0)
  			sbinfo->free_blocks -= delta;

  		else
  			ret = -ENOMEM;
  		spin_unlock(&sbinfo->stat_lock);
  	}
  
  	return ret;
  }

  void hugetlb_put_quota(struct address_space *mapping, long delta)

  {
  	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
  
  	if (sbinfo->free_blocks > -1) {
  		spin_lock(&sbinfo->stat_lock);

  		sbinfo->free_blocks += delta;

  		spin_unlock(&sbinfo->stat_lock);
  	}
  }

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

  {

  	return mount_nodev(fs_type, flags, data, hugetlbfs_fill_super);

  }
  
  static struct file_system_type hugetlbfs_fs_type = {
  	.name		= "hugetlbfs",

  	.mount		= hugetlbfs_mount,

  	.kill_sb	= kill_litter_super,
  };
  
  static struct vfsmount *hugetlbfs_vfsmount;

  static int can_do_hugetlb_shm(void)

  {

  	return capable(CAP_IPC_LOCK) || in_group_p(sysctl_hugetlb_shm_group);

  }

  struct file *hugetlb_file_setup(const char *name, size_t size,
  				vm_flags_t acctflag,

  				struct user_struct **user, int creat_flags)

  {
  	int error = -ENOMEM;
  	struct file *file;
  	struct inode *inode;

  	struct path path;
  	struct dentry *root;

  	struct qstr quick_string;

  	*user = NULL;

  	if (!hugetlbfs_vfsmount)
  		return ERR_PTR(-ENOENT);

  	if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {

  		*user = current_user();
  		if (user_shm_lock(size, *user)) {

  			printk_once(KERN_WARNING "Using mlock ulimits for SHM_HUGETLB is deprecated
  ");

  		} else {
  			*user = NULL;

  			return ERR_PTR(-EPERM);

  		}

  	}

  	root = hugetlbfs_vfsmount->mnt_root;

  	quick_string.name = name;

  	quick_string.len = strlen(quick_string.name);
  	quick_string.hash = 0;

  	path.dentry = d_alloc(root, &quick_string);
  	if (!path.dentry)

  		goto out_shm_unlock;

  	path.mnt = mntget(hugetlbfs_vfsmount);

  	error = -ENOSPC;

  	inode = hugetlbfs_get_inode(root->d_sb, current_fsuid(),
  				current_fsgid(), S_IFREG | S_IRWXUGO, 0);

  	if (!inode)

  		goto out_dentry;

  	error = -ENOMEM;

  	if (hugetlb_reserve_pages(inode, 0,

  			size >> huge_page_shift(hstate_inode(inode)), NULL,
  			acctflag))

  		goto out_inode;

  	d_instantiate(path.dentry, inode);

  	inode->i_size = size;

  	clear_nlink(inode);

  
  	error = -ENFILE;

  	file = alloc_file(&path, FMODE_WRITE | FMODE_READ,

  			&hugetlbfs_file_operations);
  	if (!file)

  		goto out_dentry; /* inode is already attached */

  	return file;

  out_inode:
  	iput(inode);

  out_dentry:

  	path_put(&path);

  out_shm_unlock:

  	if (*user) {
  		user_shm_unlock(size, *user);
  		*user = NULL;
  	}

  	return ERR_PTR(error);
  }
  
  static int __init init_hugetlbfs_fs(void)
  {
  	int error;
  	struct vfsmount *vfsmount;

  	error = bdi_init(&hugetlbfs_backing_dev_info);
  	if (error)
  		return error;

  	hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
  					sizeof(struct hugetlbfs_inode_info),

  					0, 0, init_once);

  	if (hugetlbfs_inode_cachep == NULL)

  		goto out2;

  
  	error = register_filesystem(&hugetlbfs_fs_type);
  	if (error)
  		goto out;
  
  	vfsmount = kern_mount(&hugetlbfs_fs_type);
  
  	if (!IS_ERR(vfsmount)) {
  		hugetlbfs_vfsmount = vfsmount;
  		return 0;
  	}
  
  	error = PTR_ERR(vfsmount);
  
   out:
  	if (error)
  		kmem_cache_destroy(hugetlbfs_inode_cachep);

   out2:
  	bdi_destroy(&hugetlbfs_backing_dev_info);

  	return error;
  }
  
  static void __exit exit_hugetlbfs_fs(void)
  {
  	kmem_cache_destroy(hugetlbfs_inode_cachep);

  	kern_unmount(hugetlbfs_vfsmount);

  	unregister_filesystem(&hugetlbfs_fs_type);

  	bdi_destroy(&hugetlbfs_backing_dev_info);

  }
  
  module_init(init_hugetlbfs_fs)
  module_exit(exit_hugetlbfs_fs)
  
  MODULE_LICENSE("GPL");