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32 results

inode.c

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  • inode.c 19.44 KiB
    /*
     * 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/capability.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 const struct address_space_operations hugetlbfs_aops;
    const 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 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_dentry->d_inode;
    	loff_t len, vma_len;
    	int ret;
    
    	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);
    
    	mutex_lock(&inode->i_mutex);
    	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_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).
     */
    
    #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;
    
    	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)
    {
    	clear_page_dirty(page);
    	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);
    }
    
    /*
     * 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_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;
    
    		__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)
    {
    	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(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;
    }
    
    /*
     * For direct-IO reads into hugetlb pages
     */
    static int hugetlbfs_set_page_dirty(struct page *page)
    {
    	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 kmem_cache_t *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, SLAB_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, 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);
    }
    
    const 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,
    	.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 *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 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_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];
    	static atomic_t counter;
    
    	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;
    	snprintf(buf, 16, "%u", atomic_inc_return(&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;
    
    	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_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_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, 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");