Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 860 insertions, 0 deletions

diff --git a/fs/super.c b/fs/super.c
new file mode 100644
index 000000000000..3a1b8ca04ba6
--- /dev/null
+++ b/fs/super.c
@@ -0,0 +1,860 @@
+/*
+ *  linux/fs/super.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  super.c contains code to handle: - mount structures
+ *                                   - super-block tables
+ *                                   - filesystem drivers list
+ *                                   - mount system call
+ *                                   - umount system call
+ *                                   - ustat system call
+ *
+ * GK 2/5/95  -  Changed to support mounting the root fs via NFS
+ *
+ *  Added kerneld support: Jacques Gelinas and Bjorn Ekwall
+ *  Added change_root: Werner Almesberger & Hans Lermen, Feb '96
+ *  Added options to /proc/mounts:
+ *    Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
+ *  Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
+ *  Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/smp_lock.h>
+#include <linux/acct.h>
+#include <linux/blkdev.h>
+#include <linux/quotaops.h>
+#include <linux/namei.h>
+#include <linux/buffer_head.h>		/* for fsync_super() */
+#include <linux/mount.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/vfs.h>
+#include <linux/writeback.h>		/* for the emergency remount stuff */
+#include <linux/idr.h>
+#include <linux/kobject.h>
+#include <asm/uaccess.h>
+
+
+void get_filesystem(struct file_system_type *fs);
+void put_filesystem(struct file_system_type *fs);
+struct file_system_type *get_fs_type(const char *name);
+
+LIST_HEAD(super_blocks);
+DEFINE_SPINLOCK(sb_lock);
+
+/**
+ *	alloc_super	-	create new superblock
+ *
+ *	Allocates and initializes a new &struct super_block.  alloc_super()
+ *	returns a pointer new superblock or %NULL if allocation had failed.
+ */
+static struct super_block *alloc_super(void)
+{
+	struct super_block *s = kmalloc(sizeof(struct super_block),  GFP_USER);
+	static struct super_operations default_op;
+
+	if (s) {
+		memset(s, 0, sizeof(struct super_block));
+		if (security_sb_alloc(s)) {
+			kfree(s);
+			s = NULL;
+			goto out;
+		}
+		INIT_LIST_HEAD(&s->s_dirty);
+		INIT_LIST_HEAD(&s->s_io);
+		INIT_LIST_HEAD(&s->s_files);
+		INIT_LIST_HEAD(&s->s_instances);
+		INIT_HLIST_HEAD(&s->s_anon);
+		INIT_LIST_HEAD(&s->s_inodes);
+		init_rwsem(&s->s_umount);
+		sema_init(&s->s_lock, 1);
+		down_write(&s->s_umount);
+		s->s_count = S_BIAS;
+		atomic_set(&s->s_active, 1);
+		sema_init(&s->s_vfs_rename_sem,1);
+		sema_init(&s->s_dquot.dqio_sem, 1);
+		sema_init(&s->s_dquot.dqonoff_sem, 1);
+		init_rwsem(&s->s_dquot.dqptr_sem);
+		init_waitqueue_head(&s->s_wait_unfrozen);
+		s->s_maxbytes = MAX_NON_LFS;
+		s->dq_op = sb_dquot_ops;
+		s->s_qcop = sb_quotactl_ops;
+		s->s_op = &default_op;
+		s->s_time_gran = 1000000000;
+	}
+out:
+	return s;
+}
+
+/**
+ *	destroy_super	-	frees a superblock
+ *	@s: superblock to free
+ *
+ *	Frees a superblock.
+ */
+static inline void destroy_super(struct super_block *s)
+{
+	security_sb_free(s);
+	kfree(s);
+}
+
+/* Superblock refcounting  */
+
+/*
+ * Drop a superblock's refcount.  Returns non-zero if the superblock was
+ * destroyed.  The caller must hold sb_lock.
+ */
+int __put_super(struct super_block *sb)
+{
+	int ret = 0;
+
+	if (!--sb->s_count) {
+		destroy_super(sb);
+		ret = 1;
+	}
+	return ret;
+}
+
+/*
+ * Drop a superblock's refcount.
+ * Returns non-zero if the superblock is about to be destroyed and
+ * at least is already removed from super_blocks list, so if we are
+ * making a loop through super blocks then we need to restart.
+ * The caller must hold sb_lock.
+ */
+int __put_super_and_need_restart(struct super_block *sb)
+{
+	/* check for race with generic_shutdown_super() */
+	if (list_empty(&sb->s_list)) {
+		/* super block is removed, need to restart... */
+		__put_super(sb);
+		return 1;
+	}
+	/* can't be the last, since s_list is still in use */
+	sb->s_count--;
+	BUG_ON(sb->s_count == 0);
+	return 0;
+}
+
+/**
+ *	put_super	-	drop a temporary reference to superblock
+ *	@sb: superblock in question
+ *
+ *	Drops a temporary reference, frees superblock if there's no
+ *	references left.
+ */
+static void put_super(struct super_block *sb)
+{
+	spin_lock(&sb_lock);
+	__put_super(sb);
+	spin_unlock(&sb_lock);
+}
+
+
+/**
+ *	deactivate_super	-	drop an active reference to superblock
+ *	@s: superblock to deactivate
+ *
+ *	Drops an active reference to superblock, acquiring a temprory one if
+ *	there is no active references left.  In that case we lock superblock,
+ *	tell fs driver to shut it down and drop the temporary reference we
+ *	had just acquired.
+ */
+void deactivate_super(struct super_block *s)
+{
+	struct file_system_type *fs = s->s_type;
+	if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
+		s->s_count -= S_BIAS-1;
+		spin_unlock(&sb_lock);
+		down_write(&s->s_umount);
+		fs->kill_sb(s);
+		put_filesystem(fs);
+		put_super(s);
+	}
+}
+
+EXPORT_SYMBOL(deactivate_super);
+
+/**
+ *	grab_super - acquire an active reference
+ *	@s: reference we are trying to make active
+ *
+ *	Tries to acquire an active reference.  grab_super() is used when we
+ * 	had just found a superblock in super_blocks or fs_type->fs_supers
+ *	and want to turn it into a full-blown active reference.  grab_super()
+ *	is called with sb_lock held and drops it.  Returns 1 in case of
+ *	success, 0 if we had failed (superblock contents was already dead or
+ *	dying when grab_super() had been called).
+ */
+static int grab_super(struct super_block *s)
+{
+	s->s_count++;
+	spin_unlock(&sb_lock);
+	down_write(&s->s_umount);
+	if (s->s_root) {
+		spin_lock(&sb_lock);
+		if (s->s_count > S_BIAS) {
+			atomic_inc(&s->s_active);
+			s->s_count--;
+			spin_unlock(&sb_lock);
+			return 1;
+		}
+		spin_unlock(&sb_lock);
+	}
+	up_write(&s->s_umount);
+	put_super(s);
+	yield();
+	return 0;
+}
+
+/**
+ *	generic_shutdown_super	-	common helper for ->kill_sb()
+ *	@sb: superblock to kill
+ *
+ *	generic_shutdown_super() does all fs-independent work on superblock
+ *	shutdown.  Typical ->kill_sb() should pick all fs-specific objects
+ *	that need destruction out of superblock, call generic_shutdown_super()
+ *	and release aforementioned objects.  Note: dentries and inodes _are_
+ *	taken care of and do not need specific handling.
+ */
+void generic_shutdown_super(struct super_block *sb)
+{
+	struct dentry *root = sb->s_root;
+	struct super_operations *sop = sb->s_op;
+
+	if (root) {
+		sb->s_root = NULL;
+		shrink_dcache_parent(root);
+		shrink_dcache_anon(&sb->s_anon);
+		dput(root);
+		fsync_super(sb);
+		lock_super(sb);
+		sb->s_flags &= ~MS_ACTIVE;
+		/* bad name - it should be evict_inodes() */
+		invalidate_inodes(sb);
+		lock_kernel();
+
+		if (sop->write_super && sb->s_dirt)
+			sop->write_super(sb);
+		if (sop->put_super)
+			sop->put_super(sb);
+
+		/* Forget any remaining inodes */
+		if (invalidate_inodes(sb)) {
+			printk("VFS: Busy inodes after unmount. "
+			   "Self-destruct in 5 seconds.  Have a nice day...\n");
+		}
+
+		unlock_kernel();
+		unlock_super(sb);
+	}
+	spin_lock(&sb_lock);
+	/* should be initialized for __put_super_and_need_restart() */
+	list_del_init(&sb->s_list);
+	list_del(&sb->s_instances);
+	spin_unlock(&sb_lock);
+	up_write(&sb->s_umount);
+}
+
+EXPORT_SYMBOL(generic_shutdown_super);
+
+/**
+ *	sget	-	find or create a superblock
+ *	@type:	filesystem type superblock should belong to
+ *	@test:	comparison callback
+ *	@set:	setup callback
+ *	@data:	argument to each of them
+ */
+struct super_block *sget(struct file_system_type *type,
+			int (*test)(struct super_block *,void *),
+			int (*set)(struct super_block *,void *),
+			void *data)
+{
+	struct super_block *s = NULL;
+	struct list_head *p;
+	int err;
+
+retry:
+	spin_lock(&sb_lock);
+	if (test) list_for_each(p, &type->fs_supers) {
+		struct super_block *old;
+		old = list_entry(p, struct super_block, s_instances);
+		if (!test(old, data))
+			continue;
+		if (!grab_super(old))
+			goto retry;
+		if (s)
+			destroy_super(s);
+		return old;
+	}
+	if (!s) {
+		spin_unlock(&sb_lock);
+		s = alloc_super();
+		if (!s)
+			return ERR_PTR(-ENOMEM);
+		goto retry;
+	}
+		
+	err = set(s, data);
+	if (err) {
+		spin_unlock(&sb_lock);
+		destroy_super(s);
+		return ERR_PTR(err);
+	}
+	s->s_type = type;
+	strlcpy(s->s_id, type->name, sizeof(s->s_id));
+	list_add_tail(&s->s_list, &super_blocks);
+	list_add(&s->s_instances, &type->fs_supers);
+	spin_unlock(&sb_lock);
+	get_filesystem(type);
+	return s;
+}
+
+EXPORT_SYMBOL(sget);
+
+void drop_super(struct super_block *sb)
+{
+	up_read(&sb->s_umount);
+	put_super(sb);
+}
+
+EXPORT_SYMBOL(drop_super);
+
+static inline void write_super(struct super_block *sb)
+{
+	lock_super(sb);
+	if (sb->s_root && sb->s_dirt)
+		if (sb->s_op->write_super)
+			sb->s_op->write_super(sb);
+	unlock_super(sb);
+}
+
+/*
+ * Note: check the dirty flag before waiting, so we don't
+ * hold up the sync while mounting a device. (The newly
+ * mounted device won't need syncing.)
+ */
+void sync_supers(void)
+{
+	struct super_block * sb;
+restart:
+	spin_lock(&sb_lock);
+	sb = sb_entry(super_blocks.next);
+	while (sb != sb_entry(&super_blocks))
+		if (sb->s_dirt) {
+			sb->s_count++;
+			spin_unlock(&sb_lock);
+			down_read(&sb->s_umount);
+			write_super(sb);
+			drop_super(sb);
+			goto restart;
+		} else
+			sb = sb_entry(sb->s_list.next);
+	spin_unlock(&sb_lock);
+}
+
+/*
+ * Call the ->sync_fs super_op against all filesytems which are r/w and
+ * which implement it.
+ *
+ * This operation is careful to avoid the livelock which could easily happen
+ * if two or more filesystems are being continuously dirtied.  s_need_sync_fs
+ * is used only here.  We set it against all filesystems and then clear it as
+ * we sync them.  So redirtied filesystems are skipped.
+ *
+ * But if process A is currently running sync_filesytems and then process B
+ * calls sync_filesystems as well, process B will set all the s_need_sync_fs
+ * flags again, which will cause process A to resync everything.  Fix that with
+ * a local mutex.
+ *
+ * (Fabian) Avoid sync_fs with clean fs & wait mode 0
+ */
+void sync_filesystems(int wait)
+{
+	struct super_block *sb;
+	static DECLARE_MUTEX(mutex);
+
+	down(&mutex);		/* Could be down_interruptible */
+	spin_lock(&sb_lock);
+	for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks);
+			sb = sb_entry(sb->s_list.next)) {
+		if (!sb->s_op->sync_fs)
+			continue;
+		if (sb->s_flags & MS_RDONLY)
+			continue;
+		sb->s_need_sync_fs = 1;
+	}
+	spin_unlock(&sb_lock);
+
+restart:
+	spin_lock(&sb_lock);
+	for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks);
+			sb = sb_entry(sb->s_list.next)) {
+		if (!sb->s_need_sync_fs)
+			continue;
+		sb->s_need_sync_fs = 0;
+		if (sb->s_flags & MS_RDONLY)
+			continue;	/* hm.  Was remounted r/o meanwhile */
+		sb->s_count++;
+		spin_unlock(&sb_lock);
+		down_read(&sb->s_umount);
+		if (sb->s_root && (wait || sb->s_dirt))
+			sb->s_op->sync_fs(sb, wait);
+		drop_super(sb);
+		goto restart;
+	}
+	spin_unlock(&sb_lock);
+	up(&mutex);
+}
+
+/**
+ *	get_super - get the superblock of a device
+ *	@bdev: device to get the superblock for
+ *	
+ *	Scans the superblock list and finds the superblock of the file system
+ *	mounted on the device given. %NULL is returned if no match is found.
+ */
+
+struct super_block * get_super(struct block_device *bdev)
+{
+	struct list_head *p;
+	if (!bdev)
+		return NULL;
+rescan:
+	spin_lock(&sb_lock);
+	list_for_each(p, &super_blocks) {
+		struct super_block *s = sb_entry(p);
+		if (s->s_bdev == bdev) {
+			s->s_count++;
+			spin_unlock(&sb_lock);
+			down_read(&s->s_umount);
+			if (s->s_root)
+				return s;
+			drop_super(s);
+			goto rescan;
+		}
+	}
+	spin_unlock(&sb_lock);
+	return NULL;
+}
+
+EXPORT_SYMBOL(get_super);
+ 
+struct super_block * user_get_super(dev_t dev)
+{
+	struct list_head *p;
+
+rescan:
+	spin_lock(&sb_lock);
+	list_for_each(p, &super_blocks) {
+		struct super_block *s = sb_entry(p);
+		if (s->s_dev ==  dev) {
+			s->s_count++;
+			spin_unlock(&sb_lock);
+			down_read(&s->s_umount);
+			if (s->s_root)
+				return s;
+			drop_super(s);
+			goto rescan;
+		}
+	}
+	spin_unlock(&sb_lock);
+	return NULL;
+}
+
+EXPORT_SYMBOL(user_get_super);
+
+asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf)
+{
+        struct super_block *s;
+        struct ustat tmp;
+        struct kstatfs sbuf;
+	int err = -EINVAL;
+
+        s = user_get_super(new_decode_dev(dev));
+        if (s == NULL)
+                goto out;
+	err = vfs_statfs(s, &sbuf);
+	drop_super(s);
+	if (err)
+		goto out;
+
+        memset(&tmp,0,sizeof(struct ustat));
+        tmp.f_tfree = sbuf.f_bfree;
+        tmp.f_tinode = sbuf.f_ffree;
+
+        err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
+out:
+	return err;
+}
+
+/**
+ *	mark_files_ro
+ *	@sb: superblock in question
+ *
+ *	All files are marked read/only.  We don't care about pending
+ *	delete files so this should be used in 'force' mode only
+ */
+
+static void mark_files_ro(struct super_block *sb)
+{
+	struct file *f;
+
+	file_list_lock();
+	list_for_each_entry(f, &sb->s_files, f_list) {
+		if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
+			f->f_mode &= ~FMODE_WRITE;
+	}
+	file_list_unlock();
+}
+
+/**
+ *	do_remount_sb - asks filesystem to change mount options.
+ *	@sb:	superblock in question
+ *	@flags:	numeric part of options
+ *	@data:	the rest of options
+ *      @force: whether or not to force the change
+ *
+ *	Alters the mount options of a mounted file system.
+ */
+int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
+{
+	int retval;
+	
+	if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
+		return -EACCES;
+	if (flags & MS_RDONLY)
+		acct_auto_close(sb);
+	shrink_dcache_sb(sb);
+	fsync_super(sb);
+
+	/* If we are remounting RDONLY and current sb is read/write,
+	   make sure there are no rw files opened */
+	if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
+		if (force)
+			mark_files_ro(sb);
+		else if (!fs_may_remount_ro(sb))
+			return -EBUSY;
+	}
+
+	if (sb->s_op->remount_fs) {
+		lock_super(sb);
+		retval = sb->s_op->remount_fs(sb, &flags, data);
+		unlock_super(sb);
+		if (retval)
+			return retval;
+	}
+	sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
+	return 0;
+}
+
+static void do_emergency_remount(unsigned long foo)
+{
+	struct super_block *sb;
+
+	spin_lock(&sb_lock);
+	list_for_each_entry(sb, &super_blocks, s_list) {
+		sb->s_count++;
+		spin_unlock(&sb_lock);
+		down_read(&sb->s_umount);
+		if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
+			/*
+			 * ->remount_fs needs lock_kernel().
+			 *
+			 * What lock protects sb->s_flags??
+			 */
+			lock_kernel();
+			do_remount_sb(sb, MS_RDONLY, NULL, 1);
+			unlock_kernel();
+		}
+		drop_super(sb);
+		spin_lock(&sb_lock);
+	}
+	spin_unlock(&sb_lock);
+	printk("Emergency Remount complete\n");
+}
+
+void emergency_remount(void)
+{
+	pdflush_operation(do_emergency_remount, 0);
+}
+
+/*
+ * Unnamed block devices are dummy devices used by virtual
+ * filesystems which don't use real block-devices.  -- jrs
+ */
+
+static struct idr unnamed_dev_idr;
+static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
+
+int set_anon_super(struct super_block *s, void *data)
+{
+	int dev;
+	int error;
+
+ retry:
+	if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
+		return -ENOMEM;
+	spin_lock(&unnamed_dev_lock);
+	error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
+	spin_unlock(&unnamed_dev_lock);
+	if (error == -EAGAIN)
+		/* We raced and lost with another CPU. */
+		goto retry;
+	else if (error)
+		return -EAGAIN;
+
+	if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
+		spin_lock(&unnamed_dev_lock);
+		idr_remove(&unnamed_dev_idr, dev);
+		spin_unlock(&unnamed_dev_lock);
+		return -EMFILE;
+	}
+	s->s_dev = MKDEV(0, dev & MINORMASK);
+	return 0;
+}
+
+EXPORT_SYMBOL(set_anon_super);
+
+void kill_anon_super(struct super_block *sb)
+{
+	int slot = MINOR(sb->s_dev);
+
+	generic_shutdown_super(sb);
+	spin_lock(&unnamed_dev_lock);
+	idr_remove(&unnamed_dev_idr, slot);
+	spin_unlock(&unnamed_dev_lock);
+}
+
+EXPORT_SYMBOL(kill_anon_super);
+
+void __init unnamed_dev_init(void)
+{
+	idr_init(&unnamed_dev_idr);
+}
+
+void kill_litter_super(struct super_block *sb)
+{
+	if (sb->s_root)
+		d_genocide(sb->s_root);
+	kill_anon_super(sb);
+}
+
+EXPORT_SYMBOL(kill_litter_super);
+
+static int set_bdev_super(struct super_block *s, void *data)
+{
+	s->s_bdev = data;
+	s->s_dev = s->s_bdev->bd_dev;
+	return 0;
+}
+
+static int test_bdev_super(struct super_block *s, void *data)
+{
+	return (void *)s->s_bdev == data;
+}
+
+static void bdev_uevent(struct block_device *bdev, enum kobject_action action)
+{
+	if (bdev->bd_disk) {
+		if (bdev->bd_part)
+			kobject_uevent(&bdev->bd_part->kobj, action, NULL);
+		else
+			kobject_uevent(&bdev->bd_disk->kobj, action, NULL);
+	}
+}
+
+struct super_block *get_sb_bdev(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data,
+	int (*fill_super)(struct super_block *, void *, int))
+{
+	struct block_device *bdev;
+	struct super_block *s;
+	int error = 0;
+
+	bdev = open_bdev_excl(dev_name, flags, fs_type);
+	if (IS_ERR(bdev))
+		return (struct super_block *)bdev;
+
+	/*
+	 * once the super is inserted into the list by sget, s_umount
+	 * will protect the lockfs code from trying to start a snapshot
+	 * while we are mounting
+	 */
+	down(&bdev->bd_mount_sem);
+	s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
+	up(&bdev->bd_mount_sem);
+	if (IS_ERR(s))
+		goto out;
+
+	if (s->s_root) {
+		if ((flags ^ s->s_flags) & MS_RDONLY) {
+			up_write(&s->s_umount);
+			deactivate_super(s);
+			s = ERR_PTR(-EBUSY);
+		}
+		goto out;
+	} else {
+		char b[BDEVNAME_SIZE];
+
+		s->s_flags = flags;
+		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
+		s->s_old_blocksize = block_size(bdev);
+		sb_set_blocksize(s, s->s_old_blocksize);
+		error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
+		if (error) {
+			up_write(&s->s_umount);
+			deactivate_super(s);
+			s = ERR_PTR(error);
+		} else {
+			s->s_flags |= MS_ACTIVE;
+			bdev_uevent(bdev, KOBJ_MOUNT);
+		}
+	}
+
+	return s;
+
+out:
+	close_bdev_excl(bdev);
+	return s;
+}
+
+EXPORT_SYMBOL(get_sb_bdev);
+
+void kill_block_super(struct super_block *sb)
+{
+	struct block_device *bdev = sb->s_bdev;
+
+	bdev_uevent(bdev, KOBJ_UMOUNT);
+	generic_shutdown_super(sb);
+	sync_blockdev(bdev);
+	close_bdev_excl(bdev);
+}
+
+EXPORT_SYMBOL(kill_block_super);
+
+struct super_block *get_sb_nodev(struct file_system_type *fs_type,
+	int flags, void *data,
+	int (*fill_super)(struct super_block *, void *, int))
+{
+	int error;
+	struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
+
+	if (IS_ERR(s))
+		return s;
+
+	s->s_flags = flags;
+
+	error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
+	if (error) {
+		up_write(&s->s_umount);
+		deactivate_super(s);
+		return ERR_PTR(error);
+	}
+	s->s_flags |= MS_ACTIVE;
+	return s;
+}
+
+EXPORT_SYMBOL(get_sb_nodev);
+
+static int compare_single(struct super_block *s, void *p)
+{
+	return 1;
+}
+
+struct super_block *get_sb_single(struct file_system_type *fs_type,
+	int flags, void *data,
+	int (*fill_super)(struct super_block *, void *, int))
+{
+	struct super_block *s;
+	int error;
+
+	s = sget(fs_type, compare_single, set_anon_super, NULL);
+	if (IS_ERR(s))
+		return s;
+	if (!s->s_root) {
+		s->s_flags = flags;
+		error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
+		if (error) {
+			up_write(&s->s_umount);
+			deactivate_super(s);
+			return ERR_PTR(error);
+		}
+		s->s_flags |= MS_ACTIVE;
+	}
+	do_remount_sb(s, flags, data, 0);
+	return s;
+}
+
+EXPORT_SYMBOL(get_sb_single);
+
+struct vfsmount *
+do_kern_mount(const char *fstype, int flags, const char *name, void *data)
+{
+	struct file_system_type *type = get_fs_type(fstype);
+	struct super_block *sb = ERR_PTR(-ENOMEM);
+	struct vfsmount *mnt;
+	int error;
+	char *secdata = NULL;
+
+	if (!type)
+		return ERR_PTR(-ENODEV);
+
+	mnt = alloc_vfsmnt(name);
+	if (!mnt)
+		goto out;
+
+	if (data) {
+		secdata = alloc_secdata();
+		if (!secdata) {
+			sb = ERR_PTR(-ENOMEM);
+			goto out_mnt;
+		}
+
+		error = security_sb_copy_data(type, data, secdata);
+		if (error) {
+			sb = ERR_PTR(error);
+			goto out_free_secdata;
+		}
+	}
+
+	sb = type->get_sb(type, flags, name, data);
+	if (IS_ERR(sb))
+		goto out_free_secdata;
+ 	error = security_sb_kern_mount(sb, secdata);
+ 	if (error)
+ 		goto out_sb;
+	mnt->mnt_sb = sb;
+	mnt->mnt_root = dget(sb->s_root);
+	mnt->mnt_mountpoint = sb->s_root;
+	mnt->mnt_parent = mnt;
+	mnt->mnt_namespace = current->namespace;
+	up_write(&sb->s_umount);
+	put_filesystem(type);
+	return mnt;
+out_sb:
+	up_write(&sb->s_umount);
+	deactivate_super(sb);
+	sb = ERR_PTR(error);
+out_free_secdata:
+	free_secdata(secdata);
+out_mnt:
+	free_vfsmnt(mnt);
+out:
+	put_filesystem(type);
+	return (struct vfsmount *)sb;
+}
+
+EXPORT_SYMBOL_GPL(do_kern_mount);
+
+struct vfsmount *kern_mount(struct file_system_type *type)
+{
+	return do_kern_mount(type->name, 0, type->name, NULL);
+}
+
+EXPORT_SYMBOL(kern_mount);