2 files changed, 860 insertions, 0 deletions

diff --git a/fs/hugetlbfs/Makefile b/fs/hugetlbfs/Makefile
new file mode 100644
index 000000000000..6adf870c63c6
--- /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 000000000000..2af3338f891b
--- /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");