2 files changed, 860 insertions, 0 deletions

diff --git a/fs/hugetlbfs/Makefile b/fs/hugetlbfs/Makefile
new file mode 100644
index 00000000000..6adf870c63c
--- /dev/null
+++ b/fs/hugetlbfs/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for the linux ramfs routines.
+#
+
+obj-$(CONFIG_HUGETLBFS) += hugetlbfs.o
+
+hugetlbfs-objs := inode.o
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
new file mode 100644
index 00000000000..2af3338f891
--- /dev/null
+++ b/fs/hugetlbfs/inode.c
@@ -0,0 +1,853 @@
+/*
+ * 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/writeback.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/hugetlb.h>
+#include <linux/pagevec.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 struct super_operations hugetlbfs_ops;
+static struct address_space_operations hugetlbfs_aops;
+struct file_operations hugetlbfs_file_operations;
+static struct inode_operations hugetlbfs_dir_inode_operations;
+static 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;
+
+static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct address_space *mapping = inode->i_mapping;
+	loff_t len, vma_len;
+	int ret;
+
+	if ((vma->vm_flags & (VM_MAYSHARE | VM_WRITE)) == VM_WRITE)
+		return -EINVAL;
+
+	if (vma->vm_pgoff & (HPAGE_SIZE / PAGE_SIZE - 1))
+		return -EINVAL;
+
+	if (vma->vm_start & ~HPAGE_MASK)
+		return -EINVAL;
+
+	if (vma->vm_end & ~HPAGE_MASK)
+		return -EINVAL;
+
+	if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
+		return -EINVAL;
+
+	vma_len = (loff_t)(vma->vm_end - vma->vm_start);
+
+	down(&inode->i_sem);
+	file_accessed(file);
+	vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
+	vma->vm_ops = &hugetlb_vm_ops;
+
+	ret = -ENOMEM;
+	len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+	if (!(vma->vm_flags & VM_WRITE) && len > inode->i_size)
+		goto out;
+
+	ret = hugetlb_prefault(mapping, vma);
+	if (ret)
+		goto out;
+
+	if (inode->i_size < len)
+		inode->i_size = len;
+out:
+	up(&inode->i_sem);
+
+	return ret;
+}
+
+/*
+ * Called under down_write(mmap_sem), page_table_lock is not held
+ */
+
+#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
+unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags);
+#else
+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 (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;
+
+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 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 void truncate_huge_page(struct page *page)
+{
+	clear_page_dirty(page);
+	ClearPageUptodate(page);
+	remove_from_page_cache(page);
+	put_page(page);
+}
+
+static void truncate_hugepages(struct address_space *mapping, loff_t lstart)
+{
+	const pgoff_t start = lstart >> HPAGE_SHIFT;
+	struct pagevec pvec;
+	pgoff_t next;
+	int i;
+
+	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);
+		}
+		huge_pagevec_release(&pvec);
+	}
+	BUG_ON(!lstart && mapping->nrpages);
+}
+
+static void hugetlbfs_delete_inode(struct inode *inode)
+{
+	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(inode->i_sb);
+
+	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);
+
+	if (inode->i_data.nrpages)
+		truncate_hugepages(&inode->i_data, 0);
+
+	security_inode_delete(inode);
+
+	if (sbinfo->free_inodes >= 0) {
+		spin_lock(&sbinfo->stat_lock);
+		sbinfo->free_inodes++;
+		spin_unlock(&sbinfo->stat_lock);
+	}
+
+	clear_inode(inode);
+	destroy_inode(inode);
+}
+
+static void hugetlbfs_forget_inode(struct inode *inode)
+{
+	struct super_block *super_block = inode->i_sb;
+	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(super_block);
+
+	if (hlist_unhashed(&inode->i_hash))
+		goto out_truncate;
+
+	if (!(inode->i_state & (I_DIRTY|I_LOCK))) {
+		list_del(&inode->i_list);
+		list_add(&inode->i_list, &inode_unused);
+	}
+	inodes_stat.nr_unused++;
+	if (!super_block || (super_block->s_flags & MS_ACTIVE)) {
+		spin_unlock(&inode_lock);
+		return;
+	}
+
+	/* write_inode_now() ? */
+	inodes_stat.nr_unused--;
+	hlist_del_init(&inode->i_hash);
+out_truncate:
+	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);
+	if (inode->i_data.nrpages)
+		truncate_hugepages(&inode->i_data, 0);
+
+	if (sbinfo->free_inodes >= 0) {
+		spin_lock(&sbinfo->stat_lock);
+		sbinfo->free_inodes++;
+		spin_unlock(&sbinfo->stat_lock);
+	}
+
+	clear_inode(inode);
+	destroy_inode(inode);
+}
+
+static void hugetlbfs_drop_inode(struct inode *inode)
+{
+	if (!inode->i_nlink)
+		hugetlbfs_delete_inode(inode);
+	else
+		hugetlbfs_forget_inode(inode);
+}
+
+/*
+ * h_pgoff is in HPAGE_SIZE units.
+ * vma->vm_pgoff is in PAGE_SIZE units.
+ */
+static inline void
+hugetlb_vmtruncate_list(struct prio_tree_root *root, unsigned long h_pgoff)
+{
+	struct vm_area_struct *vma;
+	struct prio_tree_iter iter;
+
+	vma_prio_tree_foreach(vma, &iter, root, h_pgoff, ULONG_MAX) {
+		unsigned long h_vm_pgoff;
+		unsigned long v_length;
+		unsigned long v_offset;
+
+		h_vm_pgoff = vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT);
+		v_offset = (h_pgoff - h_vm_pgoff) << HPAGE_SHIFT;
+		/*
+		 * Is this VMA fully outside the truncation point?
+		 */
+		if (h_vm_pgoff >= h_pgoff)
+			v_offset = 0;
+
+		v_length = vma->vm_end - vma->vm_start;
+
+		zap_hugepage_range(vma,
+				vma->vm_start + v_offset,
+				v_length - v_offset);
+	}
+}
+
+/*
+ * Expanding truncates are not allowed.
+ */
+static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
+{
+	unsigned long pgoff;
+	struct address_space *mapping = inode->i_mapping;
+
+	if (offset > inode->i_size)
+		return -EINVAL;
+
+	BUG_ON(offset & ~HPAGE_MASK);
+	pgoff = offset >> HPAGE_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(mapping, 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;
+	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
+
+	if (sbinfo->free_inodes >= 0) {
+		spin_lock(&sbinfo->stat_lock);
+		if (!sbinfo->free_inodes) {
+			spin_unlock(&sbinfo->stat_lock);
+			return NULL;
+		}
+		sbinfo->free_inodes--;
+		spin_unlock(&sbinfo->stat_lock);
+	}
+
+	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_blksize = HPAGE_SIZE;
+		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;
+		info = HUGETLBFS_I(inode);
+		mpol_shared_policy_init(&info->policy);
+		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) */
+			inode->i_nlink++;
+			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)
+		dir->i_nlink++;
+	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;
+}
+
+/*
+ * For direct-IO reads into hugetlb pages
+ */
+static int hugetlbfs_set_page_dirty(struct page *page)
+{
+	return 0;
+}
+
+static int hugetlbfs_statfs(struct super_block *sb, struct kstatfs *buf)
+{
+	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
+
+	buf->f_type = HUGETLBFS_MAGIC;
+	buf->f_bsize = HPAGE_SIZE;
+	if (sbinfo) {
+		spin_lock(&sbinfo->stat_lock);
+		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 kmem_cache_t *hugetlbfs_inode_cachep;
+
+static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
+{
+	struct hugetlbfs_inode_info *p;
+
+	p = kmem_cache_alloc(hugetlbfs_inode_cachep, SLAB_KERNEL);
+	if (!p)
+		return NULL;
+	return &p->vfs_inode;
+}
+
+static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
+{
+	struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
+
+	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+	    SLAB_CTOR_CONSTRUCTOR)
+		inode_init_once(&ei->vfs_inode);
+}
+
+static void hugetlbfs_destroy_inode(struct inode *inode)
+{
+	mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
+	kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
+}
+
+static 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,
+};
+
+struct file_operations hugetlbfs_file_operations = {
+	.mmap			= hugetlbfs_file_mmap,
+	.fsync			= simple_sync_file,
+	.get_unmapped_area	= hugetlb_get_unmapped_area,
+};
+
+static 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 struct inode_operations hugetlbfs_inode_operations = {
+	.setattr	= hugetlbfs_setattr,
+};
+
+static struct super_operations hugetlbfs_ops = {
+	.alloc_inode    = hugetlbfs_alloc_inode,
+	.destroy_inode  = hugetlbfs_destroy_inode,
+	.statfs		= hugetlbfs_statfs,
+	.drop_inode	= hugetlbfs_drop_inode,
+	.put_super	= hugetlbfs_put_super,
+};
+
+static int
+hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
+{
+	char *opt, *value, *rest;
+
+	if (!options)
+		return 0;
+	while ((opt = strsep(&options, ",")) != NULL) {
+		if (!*opt)
+			continue;
+
+		value = strchr(opt, '=');
+		if (!value || !*value)
+			return -EINVAL;
+		else
+			*value++ = '\0';
+
+		if (!strcmp(opt, "uid"))
+			pconfig->uid = simple_strtoul(value, &value, 0);
+		else if (!strcmp(opt, "gid"))
+			pconfig->gid = simple_strtoul(value, &value, 0);
+		else if (!strcmp(opt, "mode"))
+			pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
+		else if (!strcmp(opt, "size")) {
+			unsigned long long size = memparse(value, &rest);
+			if (*rest == '%') {
+				size <<= HPAGE_SHIFT;
+				size *= max_huge_pages;
+				do_div(size, 100);
+				rest++;
+			}
+			size &= HPAGE_MASK;
+			pconfig->nr_blocks = (size >> HPAGE_SHIFT);
+			value = rest;
+		} else if (!strcmp(opt,"nr_inodes")) {
+			pconfig->nr_inodes = memparse(value, &rest);
+			value = rest;
+		} else
+			return -EINVAL;
+
+		if (*value)
+			return -EINVAL;
+	}
+	return 0;
+}
+
+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 struct super_block *hugetlbfs_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super);
+}
+
+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;
+
+/*
+ * Return the next identifier for a shm file
+ */
+static unsigned long hugetlbfs_counter(void)
+{
+	static DEFINE_SPINLOCK(lock);
+	static unsigned long counter;
+	unsigned long ret;
+
+	spin_lock(&lock);
+	ret = ++counter;
+	spin_unlock(&lock);
+	return ret;
+}
+
+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_zero_setup(size_t size)
+{
+	int error = -ENOMEM;
+	struct file *file;
+	struct inode *inode;
+	struct dentry *dentry, *root;
+	struct qstr quick_string;
+	char buf[16];
+
+	if (!can_do_hugetlb_shm())
+		return ERR_PTR(-EPERM);
+
+	if (!is_hugepage_mem_enough(size))
+		return ERR_PTR(-ENOMEM);
+
+	if (!user_shm_lock(size, current->user))
+		return ERR_PTR(-ENOMEM);
+
+	root = hugetlbfs_vfsmount->mnt_root;
+	snprintf(buf, 16, "%lu", hugetlbfs_counter());
+	quick_string.name = buf;
+	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;
+
+	d_instantiate(dentry, inode);
+	inode->i_size = size;
+	inode->i_nlink = 0;
+	file->f_vfsmnt = mntget(hugetlbfs_vfsmount);
+	file->f_dentry = dentry;
+	file->f_mapping = inode->i_mapping;
+	file->f_op = &hugetlbfs_file_operations;
+	file->f_mode = FMODE_WRITE | FMODE_READ;
+	return file;
+
+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, NULL);
+	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");