fs/hugetlbfs/inode.c - kernel/msm-4.9 - Gitiles

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

 #include <asm/uaccess.h>

 /* some random number */
 #define HUGETLBFS_MAGIC	0x958458f6

 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 = {
 	.ra_pages	= 0,	/* No readahead */
 	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
 };

 int sysctl_hugetlb_shm_group;

 enum {
 	Opt_size, Opt_nr_inodes,
 	Opt_mode, Opt_uid, Opt_gid,
 	Opt_err,
 };

 static 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_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;

 	/*
 	 * 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 & ~(HPAGE_MASK >> 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 (vma->vm_flags & VM_MAYSHARE &&
 	    hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
 				  len >> HPAGE_SHIFT))
 		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;

 	if (len & ~HPAGE_MASK)
 		return -EINVAL;
 	if (len > TASK_SIZE)
 		return -ENOMEM;

 	if (flags & MAP_FIXED) {
 		if (prepare_hugepage_range(addr, len))
 			return -EINVAL;
 		return addr;
 	}

 	if (addr) {
 		addr = ALIGN(addr, HPAGE_SIZE);
 		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, HPAGE_SIZE);

 	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, HPAGE_SIZE);
 	}
 }
 #endif

 /*
  * Read a page. Again trivial. If it didn't already exist
  * in the page cache, it is zero-filled.
  */
 static int hugetlbfs_readpage(struct file *file, struct page * page)
 {
 	unlock_page(page);
 	return -EINVAL;
 }

 static int hugetlbfs_prepare_write(struct file *file,
 			struct page *page, unsigned offset, unsigned to)
 {
 	return -EINVAL;
 }

 static int hugetlbfs_commit_write(struct file *file,
 			struct page *page, unsigned offset, unsigned to)
 {
 	return -EINVAL;
 }

 static void truncate_huge_page(struct page *page)
 {
 	cancel_dirty_page(page, /* No IO accounting for huge pages? */0);
 	ClearPageUptodate(page);
 	remove_from_page_cache(page);
 	put_page(page);
 }

 static void truncate_hugepages(struct inode *inode, loff_t lstart)
 {
 	struct address_space *mapping = &inode->i_data;
 	const pgoff_t start = lstart >> HPAGE_SHIFT;
 	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);
 			hugetlb_put_quota(mapping);
 			freed++;
 		}
 		huge_pagevec_release(&pvec);
 	}
 	BUG_ON(!lstart && mapping->nrpages);
 	hugetlb_unreserve_pages(inode, start, freed);
 }

 static void hugetlbfs_delete_inode(struct inode *inode)
 {
 	truncate_hugepages(inode, 0);
 	clear_inode(inode);
 }

 static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
 {
 	struct super_block *sb = inode->i_sb;

 	if (!hlist_unhashed(&inode->i_hash)) {
 		if (!(inode->i_state & (I_DIRTY|I_LOCK)))
 			list_move(&inode->i_list, &inode_unused);
 		inodes_stat.nr_unused++;
 		if (!sb || (sb->s_flags & MS_ACTIVE)) {
 			spin_unlock(&inode_lock);
 			return;
 		}
 		inode->i_state |= I_WILL_FREE;
 		spin_unlock(&inode_lock);
 		/*
 		 * write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
 		 * in our backing_dev_info.
 		 */
 		write_inode_now(inode, 1);
 		spin_lock(&inode_lock);
 		inode->i_state &= ~I_WILL_FREE;
 		inodes_stat.nr_unused--;
 		hlist_del_init(&inode->i_hash);
 	}
 	list_del_init(&inode->i_list);
 	list_del_init(&inode->i_sb_list);
 	inode->i_state |= I_FREEING;
 	inodes_stat.nr_inodes--;
 	spin_unlock(&inode_lock);
 	truncate_hugepages(inode, 0);
 	clear_inode(inode);
 	destroy_inode(inode);
 }

 static void hugetlbfs_drop_inode(struct inode *inode)
 {
 	if (!inode->i_nlink)
 		generic_delete_inode(inode);
 	else
 		hugetlbfs_forget_inode(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);
 	}
 }

 /*
  * Expanding truncates are not allowed.
  */
 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 {
 	pgoff_t pgoff;
 	struct address_space *mapping = inode->i_mapping;

 	if (offset > inode->i_size)
 		return -EINVAL;

 	BUG_ON(offset & ~HPAGE_MASK);
 	pgoff = offset >> PAGE_SHIFT;

 	inode->i_size = offset;
 	spin_lock(&mapping->i_mmap_lock);
 	if (!prio_tree_empty(&mapping->i_mmap))
 		hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
 	spin_unlock(&mapping->i_mmap_lock);
 	truncate_hugepages(inode, offset);
 	return 0;
 }

 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
 	unsigned int ia_valid = attr->ia_valid;

 	BUG_ON(!inode);

 	error = inode_change_ok(inode, attr);
 	if (error)
 		goto out;

 	if (ia_valid & ATTR_SIZE) {
 		error = -EINVAL;
 		if (!(attr->ia_size & ~HPAGE_MASK))
 			error = hugetlb_vmtruncate(inode, attr->ia_size);
 		if (error)
 			goto out;
 		attr->ia_valid &= ~ATTR_SIZE;
 	}
 	error = inode_setattr(inode, attr);
 out:
 	return error;
 }

 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_mode = mode;
 		inode->i_uid = uid;
 		inode->i_gid = gid;
 		inode->i_blocks = 0;
 		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);
 		mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 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;
 		}
 	}
 	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_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);

 	buf->f_type = HUGETLBFS_MAGIC;
 	buf->f_bsize = HPAGE_SIZE;
 	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_destroy_inode(struct inode *inode)
 {
 	hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
 	mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
 	kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
 }

 static const struct address_space_operations hugetlbfs_aops = {
 	.readpage	= hugetlbfs_readpage,
 	.prepare_write	= hugetlbfs_prepare_write,
 	.commit_write	= hugetlbfs_commit_write,
 	.set_page_dirty	= hugetlbfs_set_page_dirty,
 };


 static void init_once(void *foo, struct kmem_cache *cachep, unsigned long flags)
 {
 	struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;

 	inode_init_once(&ei->vfs_inode);
 }

 const struct file_operations hugetlbfs_file_operations = {
 	.mmap			= hugetlbfs_file_mmap,
 	.fsync			= simple_sync_file,
 	.get_unmapped_area	= hugetlb_get_unmapped_area,
 };

 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,
 	.statfs		= hugetlbfs_statfs,
 	.delete_inode	= hugetlbfs_delete_inode,
 	.drop_inode	= hugetlbfs_drop_inode,
 	.put_super	= hugetlbfs_put_super,
 };

 static int
 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
 {
 	char *p, *rest;
 	substring_t args[MAX_OPT_ARGS];
 	int option;

 	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 & 0777U;
 			break;

 		case Opt_size: {
  			unsigned long long 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);
 			if (*rest == '%') {
 				size <<= HPAGE_SHIFT;
 				size *= max_huge_pages;
 				do_div(size, 100);
 			}
 			pconfig->nr_blocks = (size >> HPAGE_SHIFT);
 			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;

 		default:
 			printk(KERN_ERR "hugetlbfs: Bad mount option: \"%s\"\n",
 				 p);
 			return -EINVAL;
 			break;
 		}
 	}
 	return 0;

 bad_val:
  	printk(KERN_ERR "hugetlbfs: Bad value '%s' for mount option '%s'\n",
 	       args[0].from, p);
  	return 1;
 }

 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;

 	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;
 	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;
 	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 = HPAGE_SIZE;
 	sb->s_blocksize_bits = HPAGE_SHIFT;
 	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)
 {
 	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 > 0)
 			sbinfo->free_blocks--;
 		else
 			ret = -ENOMEM;
 		spin_unlock(&sbinfo->stat_lock);
 	}

 	return ret;
 }

 void hugetlb_put_quota(struct address_space *mapping)
 {
 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);

 	if (sbinfo->free_blocks > -1) {
 		spin_lock(&sbinfo->stat_lock);
 		sbinfo->free_blocks++;
 		spin_unlock(&sbinfo->stat_lock);
 	}
 }

 static int hugetlbfs_get_sb(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
 	return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super, mnt);
 }

 static struct file_system_type hugetlbfs_fs_type = {
 	.name		= "hugetlbfs",
 	.get_sb		= hugetlbfs_get_sb,
 	.kill_sb	= kill_litter_super,
 };

 static struct vfsmount *hugetlbfs_vfsmount;

 static int can_do_hugetlb_shm(void)
 {
 	return likely(capable(CAP_IPC_LOCK) ||
 			in_group_p(sysctl_hugetlb_shm_group) ||
 			can_do_mlock());
 }

 struct file *hugetlb_file_setup(const char *name, size_t size)
 {
 	int error = -ENOMEM;
 	struct file *file;
 	struct inode *inode;
 	struct dentry *dentry, *root;
 	struct qstr quick_string;

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

 	if (!can_do_hugetlb_shm())
 		return ERR_PTR(-EPERM);

 	if (!user_shm_lock(size, current->user))
 		return ERR_PTR(-ENOMEM);

 	root = hugetlbfs_vfsmount->mnt_root;
 	quick_string.name = name;
 	quick_string.len = strlen(quick_string.name);
 	quick_string.hash = 0;
 	dentry = d_alloc(root, &quick_string);
 	if (!dentry)
 		goto out_shm_unlock;

 	error = -ENFILE;
 	file = get_empty_filp();
 	if (!file)
 		goto out_dentry;

 	error = -ENOSPC;
 	inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
 				current->fsgid, S_IFREG | S_IRWXUGO, 0);
 	if (!inode)
 		goto out_file;

 	error = -ENOMEM;
 	if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
 		goto out_inode;

 	d_instantiate(dentry, inode);
 	inode->i_size = size;
 	inode->i_nlink = 0;
 	file->f_path.mnt = mntget(hugetlbfs_vfsmount);
 	file->f_path.dentry = dentry;
 	file->f_mapping = inode->i_mapping;
 	file->f_op = &hugetlbfs_file_operations;
 	file->f_mode = FMODE_WRITE | FMODE_READ;
 	return file;

 out_inode:
 	iput(inode);
 out_file:
 	put_filp(file);
 out_dentry:
 	dput(dentry);
 out_shm_unlock:
 	user_shm_unlock(size, current->user);
 	return ERR_PTR(error);
 }

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

 	hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
 					sizeof(struct hugetlbfs_inode_info),
 					0, 0, init_once);
 	if (hugetlbfs_inode_cachep == NULL)
 		return -ENOMEM;

 	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);
 	return error;
 }

 static void __exit exit_hugetlbfs_fs(void)
 {
 	kmem_cache_destroy(hugetlbfs_inode_cachep);
 	unregister_filesystem(&hugetlbfs_fs_type);
 }

 module_init(init_hugetlbfs_fs)
 module_exit(exit_hugetlbfs_fs)

 MODULE_LICENSE("GPL");
	/*
	* 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/quotaops.h>
	#include <linux/slab.h>
	#include <linux/dnotify.h>
	#include <linux/statfs.h>
	#include <linux/security.h>

	#include <asm/uaccess.h>

	/* some random number */
	#define HUGETLBFS_MAGIC 0x958458f6

	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 = {
	.ra_pages = 0, /* No readahead */
	.capabilities = BDI_CAP_NO_ACCT_DIRTY \| BDI_CAP_NO_WRITEBACK,
	};

	int sysctl_hugetlb_shm_group;

	enum {
	Opt_size, Opt_nr_inodes,
	Opt_mode, Opt_uid, Opt_gid,
	Opt_err,
	};

	static 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_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;

	/*
	* 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 & ~(HPAGE_MASK >> 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 (vma->vm_flags & VM_MAYSHARE &&
	hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
	len >> HPAGE_SHIFT))
	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;

	if (len & ~HPAGE_MASK)
	return -EINVAL;
	if (len > TASK_SIZE)
	return -ENOMEM;

	if (flags & MAP_FIXED) {
	if (prepare_hugepage_range(addr, len))
	return -EINVAL;
	return addr;
	}

	if (addr) {
	addr = ALIGN(addr, HPAGE_SIZE);
	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, HPAGE_SIZE);

	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, HPAGE_SIZE);
	}
	}
	#endif

	/*
	* Read a page. Again trivial. If it didn't already exist
	* in the page cache, it is zero-filled.
	*/
	static int hugetlbfs_readpage(struct file file, struct page page)
	{
	unlock_page(page);
	return -EINVAL;
	}

	static int hugetlbfs_prepare_write(struct file *file,
	struct page *page, unsigned offset, unsigned to)
	{
	return -EINVAL;
	}

	static int hugetlbfs_commit_write(struct file *file,
	struct page *page, unsigned offset, unsigned to)
	{
	return -EINVAL;
	}

	static void truncate_huge_page(struct page *page)
	{
	cancel_dirty_page(page, /* No IO accounting for huge pages? */0);
	ClearPageUptodate(page);
	remove_from_page_cache(page);
	put_page(page);
	}

	static void truncate_hugepages(struct inode *inode, loff_t lstart)
	{
	struct address_space *mapping = &inode->i_data;
	const pgoff_t start = lstart >> HPAGE_SHIFT;
	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);
	hugetlb_put_quota(mapping);
	freed++;
	}
	huge_pagevec_release(&pvec);
	}
	BUG_ON(!lstart && mapping->nrpages);
	hugetlb_unreserve_pages(inode, start, freed);
	}

	static void hugetlbfs_delete_inode(struct inode *inode)
	{
	truncate_hugepages(inode, 0);
	clear_inode(inode);
	}

	static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
	{
	struct super_block *sb = inode->i_sb;

	if (!hlist_unhashed(&inode->i_hash)) {
	if (!(inode->i_state & (I_DIRTY\|I_LOCK)))
	list_move(&inode->i_list, &inode_unused);
	inodes_stat.nr_unused++;
	if (!sb \|\| (sb->s_flags & MS_ACTIVE)) {
	spin_unlock(&inode_lock);
	return;
	}
	inode->i_state \|= I_WILL_FREE;
	spin_unlock(&inode_lock);
	/*
	* write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
	* in our backing_dev_info.
	*/
	write_inode_now(inode, 1);
	spin_lock(&inode_lock);
	inode->i_state &= ~I_WILL_FREE;
	inodes_stat.nr_unused--;
	hlist_del_init(&inode->i_hash);
	}
	list_del_init(&inode->i_list);
	list_del_init(&inode->i_sb_list);
	inode->i_state \|= I_FREEING;
	inodes_stat.nr_inodes--;
	spin_unlock(&inode_lock);
	truncate_hugepages(inode, 0);
	clear_inode(inode);
	destroy_inode(inode);
	}

	static void hugetlbfs_drop_inode(struct inode *inode)
	{
	if (!inode->i_nlink)
	generic_delete_inode(inode);
	else
	hugetlbfs_forget_inode(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);
	}
	}

	/*
	* Expanding truncates are not allowed.
	*/
	static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
	{
	pgoff_t pgoff;
	struct address_space *mapping = inode->i_mapping;

	if (offset > inode->i_size)
	return -EINVAL;

	BUG_ON(offset & ~HPAGE_MASK);
	pgoff = offset >> PAGE_SHIFT;

	inode->i_size = offset;
	spin_lock(&mapping->i_mmap_lock);
	if (!prio_tree_empty(&mapping->i_mmap))
	hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
	spin_unlock(&mapping->i_mmap_lock);
	truncate_hugepages(inode, offset);
	return 0;
	}

	static int hugetlbfs_setattr(struct dentry dentry, struct iattr attr)
	{
	struct inode *inode = dentry->d_inode;
	int error;
	unsigned int ia_valid = attr->ia_valid;

	BUG_ON(!inode);

	error = inode_change_ok(inode, attr);
	if (error)
	goto out;

	if (ia_valid & ATTR_SIZE) {
	error = -EINVAL;
	if (!(attr->ia_size & ~HPAGE_MASK))
	error = hugetlb_vmtruncate(inode, attr->ia_size);
	if (error)
	goto out;
	attr->ia_valid &= ~ATTR_SIZE;
	}
	error = inode_setattr(inode, attr);
	out:
	return error;
	}

	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_mode = mode;
	inode->i_uid = uid;
	inode->i_gid = gid;
	inode->i_blocks = 0;
	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);
	mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 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;
	}
	}
	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_statfs(struct dentry dentry, struct kstatfs buf)
	{
	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);

	buf->f_type = HUGETLBFS_MAGIC;
	buf->f_bsize = HPAGE_SIZE;
	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_destroy_inode(struct inode *inode)
	{
	hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
	mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
	kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
	}

	static const struct address_space_operations hugetlbfs_aops = {
	.readpage = hugetlbfs_readpage,
	.prepare_write = hugetlbfs_prepare_write,
	.commit_write = hugetlbfs_commit_write,
	.set_page_dirty = hugetlbfs_set_page_dirty,
	};


	static void init_once(void foo, struct kmem_cache cachep, unsigned long flags)
	{
	struct hugetlbfs_inode_info ei = (struct hugetlbfs_inode_info )foo;

	inode_init_once(&ei->vfs_inode);
	}

	const struct file_operations hugetlbfs_file_operations = {
	.mmap = hugetlbfs_file_mmap,
	.fsync = simple_sync_file,
	.get_unmapped_area = hugetlb_get_unmapped_area,
	};

	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,
	.statfs = hugetlbfs_statfs,
	.delete_inode = hugetlbfs_delete_inode,
	.drop_inode = hugetlbfs_drop_inode,
	.put_super = hugetlbfs_put_super,
	};

	static int
	hugetlbfs_parse_options(char options, struct hugetlbfs_config pconfig)
	{
	char p, rest;
	substring_t args[MAX_OPT_ARGS];
	int option;

	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 & 0777U;
	break;

	case Opt_size: {
	unsigned long long 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);
	if (*rest == '%') {
	size <<= HPAGE_SHIFT;
	size *= max_huge_pages;
	do_div(size, 100);
	}
	pconfig->nr_blocks = (size >> HPAGE_SHIFT);
	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;

	default:
	printk(KERN_ERR "hugetlbfs: Bad mount option: \"%s\"\n",
	p);
	return -EINVAL;
	break;
	}
	}
	return 0;

	bad_val:
	printk(KERN_ERR "hugetlbfs: Bad value '%s' for mount option '%s'\n",
	args[0].from, p);
	return 1;
	}

	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;

	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;
	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;
	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 = HPAGE_SIZE;
	sb->s_blocksize_bits = HPAGE_SHIFT;
	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)
	{
	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 > 0)
	sbinfo->free_blocks--;
	else
	ret = -ENOMEM;
	spin_unlock(&sbinfo->stat_lock);
	}

	return ret;
	}

	void hugetlb_put_quota(struct address_space *mapping)
	{
	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);

	if (sbinfo->free_blocks > -1) {
	spin_lock(&sbinfo->stat_lock);
	sbinfo->free_blocks++;
	spin_unlock(&sbinfo->stat_lock);
	}
	}

	static int hugetlbfs_get_sb(struct file_system_type *fs_type,
	int flags, const char dev_name, void data, struct vfsmount *mnt)
	{
	return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super, mnt);
	}

	static struct file_system_type hugetlbfs_fs_type = {
	.name = "hugetlbfs",
	.get_sb = hugetlbfs_get_sb,
	.kill_sb = kill_litter_super,
	};

	static struct vfsmount *hugetlbfs_vfsmount;

	static int can_do_hugetlb_shm(void)
	{
	return likely(capable(CAP_IPC_LOCK) \|\|
	in_group_p(sysctl_hugetlb_shm_group) \|\|
	can_do_mlock());
	}

	struct file hugetlb_file_setup(const char name, size_t size)
	{
	int error = -ENOMEM;
	struct file *file;
	struct inode *inode;
	struct dentry dentry, root;
	struct qstr quick_string;

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

	if (!can_do_hugetlb_shm())
	return ERR_PTR(-EPERM);

	if (!user_shm_lock(size, current->user))
	return ERR_PTR(-ENOMEM);

	root = hugetlbfs_vfsmount->mnt_root;
	quick_string.name = name;
	quick_string.len = strlen(quick_string.name);
	quick_string.hash = 0;
	dentry = d_alloc(root, &quick_string);
	if (!dentry)
	goto out_shm_unlock;

	error = -ENFILE;
	file = get_empty_filp();
	if (!file)
	goto out_dentry;

	error = -ENOSPC;
	inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
	current->fsgid, S_IFREG \| S_IRWXUGO, 0);
	if (!inode)
	goto out_file;

	error = -ENOMEM;
	if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
	goto out_inode;

	d_instantiate(dentry, inode);
	inode->i_size = size;
	inode->i_nlink = 0;
	file->f_path.mnt = mntget(hugetlbfs_vfsmount);
	file->f_path.dentry = dentry;
	file->f_mapping = inode->i_mapping;
	file->f_op = &hugetlbfs_file_operations;
	file->f_mode = FMODE_WRITE \| FMODE_READ;
	return file;

	out_inode:
	iput(inode);
	out_file:
	put_filp(file);
	out_dentry:
	dput(dentry);
	out_shm_unlock:
	user_shm_unlock(size, current->user);
	return ERR_PTR(error);
	}

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

	hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
	sizeof(struct hugetlbfs_inode_info),
	0, 0, init_once);
	if (hugetlbfs_inode_cachep == NULL)
	return -ENOMEM;

	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);
	return error;
	}

	static void __exit exit_hugetlbfs_fs(void)
	{
	kmem_cache_destroy(hugetlbfs_inode_cachep);
	unregister_filesystem(&hugetlbfs_fs_type);
	}

	module_init(init_hugetlbfs_fs)
	module_exit(exit_hugetlbfs_fs)

	MODULE_LICENSE("GPL");