Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull more vfs updates from Al Viro:
 "Assorted stuff from this cycle.  The big ones here are multilayer
  overlayfs from Miklos and beginning of sorting ->d_inode accesses out
  from David"

* 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (51 commits)
  autofs4 copy_dev_ioctl(): keep the value of ->size we'd used for allocation
  procfs: fix race between symlink removals and traversals
  debugfs: leave freeing a symlink body until inode eviction
  Documentation/filesystems/Locking: ->get_sb() is long gone
  trylock_super(): replacement for grab_super_passive()
  fanotify: Fix up scripted S_ISDIR/S_ISREG/S_ISLNK conversions
  Cachefiles: Fix up scripted S_ISDIR/S_ISREG/S_ISLNK conversions
  VFS: (Scripted) Convert S_ISLNK/DIR/REG(dentry->d_inode) to d_is_*(dentry)
  SELinux: Use d_is_positive() rather than testing dentry->d_inode
  Smack: Use d_is_positive() rather than testing dentry->d_inode
  TOMOYO: Use d_is_dir() rather than d_inode and S_ISDIR()
  Apparmor: Use d_is_positive/negative() rather than testing dentry->d_inode
  Apparmor: mediated_filesystem() should use dentry->d_sb not inode->i_sb
  VFS: Split DCACHE_FILE_TYPE into regular and special types
  VFS: Add a fallthrough flag for marking virtual dentries
  VFS: Add a whiteout dentry type
  VFS: Introduce inode-getting helpers for layered/unioned fs environments
  Infiniband: Fix potential NULL d_inode dereference
  posix_acl: fix reference leaks in posix_acl_create
  autofs4: Wrong format for printing dentry
  ...

Documentation/filesystems/Locking

@@ -164,8 +164,6 @@ the block device inode.  See there for more details.
 
 --------------------------- file_system_type ---------------------------
 prototypes:
-	int (*get_sb) (struct file_system_type *, int,
-		       const char *, void *, struct vfsmount *);
 	struct dentry *(*mount) (struct file_system_type *, int,
 		       const char *, void *);
 	void (*kill_sb) (struct super_block *);

Documentation/filesystems/overlayfs.txt

@@ -159,6 +159,22 @@ overlay filesystem (though an operation on the name of the file such as
 rename or unlink will of course be noticed and handled).
 
 
+Multiple lower layers
+---------------------
+
+Multiple lower layers can now be given using the the colon (":") as a
+separator character between the directory names.  For example:
+
+  mount -t overlay overlay -olowerdir=/lower1:/lower2:/lower3 /merged
+
+As the example shows, "upperdir=" and "workdir=" may be omitted.  In
+that case the overlay will be read-only.
+
+The specified lower directories will be stacked beginning from the
+rightmost one and going left.  In the above example lower1 will be the
+top, lower2 the middle and lower3 the bottom layer.
+
+
 Non-standard behavior
 ---------------------
 
@@ -196,3 +212,15 @@ Changes to the underlying filesystems while part of a mounted overlay
 filesystem are not allowed.  If the underlying filesystem is changed,
 the behavior of the overlay is undefined, though it will not result in
 a crash or deadlock.
+
+Testsuite
+---------
+
+There's testsuite developed by David Howells at:
+
+  git://git.infradead.org/users/dhowells/unionmount-testsuite.git
+
+Run as root:
+
+  # cd unionmount-testsuite
+  # ./run --ov

arch/s390/hypfs/inode.c

@@ -74,7 +74,7 @@ static void hypfs_remove(struct dentry *dentry)
 	parent = dentry->d_parent;
 	mutex_lock(&parent->d_inode->i_mutex);
 	if (hypfs_positive(dentry)) {
-		if (S_ISDIR(dentry->d_inode->i_mode))
+		if (d_is_dir(dentry))
 			simple_rmdir(parent->d_inode, dentry);
 		else
 			simple_unlink(parent->d_inode, dentry);
@@ -144,36 +144,32 @@ static int hypfs_open(struct inode *inode, struct file *filp)
 	return nonseekable_open(inode, filp);
 }
 
-static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,
-			      unsigned long nr_segs, loff_t offset)
+static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-	char *data;
-	ssize_t ret;
-	struct file *filp = iocb->ki_filp;
-	/* XXX: temporary */
-	char __user *buf = iov[0].iov_base;
-	size_t count = iov[0].iov_len;
-
-	if (nr_segs != 1)
-		return -EINVAL;
-
-	data = filp->private_data;
-	ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
-	if (ret <= 0)
-		return ret;
+	struct file *file = iocb->ki_filp;
+	char *data = file->private_data;
+	size_t available = strlen(data);
+	loff_t pos = iocb->ki_pos;
+	size_t count;
 
-	iocb->ki_pos += ret;
-	file_accessed(filp);
-
-	return ret;
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= available || !iov_iter_count(to))
+		return 0;
+	count = copy_to_iter(data + pos, available - pos, to);
+	if (!count)
+		return -EFAULT;
+	iocb->ki_pos = pos + count;
+	file_accessed(file);
+	return count;
 }
-static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
-			      unsigned long nr_segs, loff_t offset)
+
+static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 	int rc;
 	struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
 	struct hypfs_sb_info *fs_info = sb->s_fs_info;
-	size_t count = iov_length(iov, nr_segs);
+	size_t count = iov_iter_count(from);
 
 	/*
 	 * Currently we only allow one update per second for two reasons:
@@ -202,6 +198,7 @@ static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	}
 	hypfs_update_update(sb);
 	rc = count;
+	iov_iter_advance(from, count);
 out:
 	mutex_unlock(&fs_info->lock);
 	return rc;
@@ -440,10 +437,10 @@ struct dentry *hypfs_create_str(struct dentry *dir,
 static const struct file_operations hypfs_file_ops = {
 	.open		= hypfs_open,
 	.release	= hypfs_release,
-	.read		= do_sync_read,
-	.write		= do_sync_write,
-	.aio_read	= hypfs_aio_read,
-	.aio_write	= hypfs_aio_write,
+	.read		= new_sync_read,
+	.write		= new_sync_write,
+	.read_iter	= hypfs_read_iter,
+	.write_iter	= hypfs_write_iter,
 	.llseek		= no_llseek,
 };
 

drivers/infiniband/hw/ipath/ipath_fs.c

@@ -277,7 +277,7 @@ static int remove_file(struct dentry *parent, char *name)
 	}
 
 	spin_lock(&tmp->d_lock);
-	if (!(d_unhashed(tmp) && tmp->d_inode)) {
+	if (!d_unhashed(tmp) && tmp->d_inode) {
 		dget_dlock(tmp);
 		__d_drop(tmp);
 		spin_unlock(&tmp->d_lock);

drivers/infiniband/hw/qib/qib_fs.c

@@ -455,7 +455,7 @@ static int remove_file(struct dentry *parent, char *name)
 	}
 
 	spin_lock(&tmp->d_lock);
-	if (!(d_unhashed(tmp) && tmp->d_inode)) {
+	if (!d_unhashed(tmp) && tmp->d_inode) {
 		__d_drop(tmp);
 		spin_unlock(&tmp->d_lock);
 		simple_unlink(parent->d_inode, tmp);

drivers/staging/lustre/lustre/llite/dcache.c

@@ -270,7 +270,7 @@ void ll_invalidate_aliases(struct inode *inode)
 
 int ll_revalidate_it_finish(struct ptlrpc_request *request,
 			    struct lookup_intent *it,
-			    struct dentry *de)
+			    struct inode *inode)
 {
 	int rc = 0;
 
@@ -280,19 +280,17 @@ int ll_revalidate_it_finish(struct ptlrpc_request *request,
 	if (it_disposition(it, DISP_LOOKUP_NEG))
 		return -ENOENT;
 
-	rc = ll_prep_inode(&de->d_inode, request, NULL, it);
+	rc = ll_prep_inode(&inode, request, NULL, it);
 
 	return rc;
 }
 
-void ll_lookup_finish_locks(struct lookup_intent *it, struct dentry *dentry)
+void ll_lookup_finish_locks(struct lookup_intent *it, struct inode *inode)
 {
 	LASSERT(it != NULL);
-	LASSERT(dentry != NULL);
 
-	if (it->d.lustre.it_lock_mode && dentry->d_inode != NULL) {
-		struct inode *inode = dentry->d_inode;
-		struct ll_sb_info *sbi = ll_i2sbi(dentry->d_inode);
+	if (it->d.lustre.it_lock_mode && inode != NULL) {
+		struct ll_sb_info *sbi = ll_i2sbi(inode);
 
 		CDEBUG(D_DLMTRACE, "setting l_data to inode %p (%lu/%u)\n",
 		       inode, inode->i_ino, inode->i_generation);

drivers/staging/lustre/lustre/llite/file.c

@@ -2912,8 +2912,8 @@ static int __ll_inode_revalidate(struct dentry *dentry, __u64 ibits)
 			oit.it_op = IT_LOOKUP;
 
 		/* Call getattr by fid, so do not provide name at all. */
-		op_data = ll_prep_md_op_data(NULL, dentry->d_inode,
-					     dentry->d_inode, NULL, 0, 0,
+		op_data = ll_prep_md_op_data(NULL, inode,
+					     inode, NULL, 0, 0,
 					     LUSTRE_OPC_ANY, NULL);
 		if (IS_ERR(op_data))
 			return PTR_ERR(op_data);
@@ -2931,7 +2931,7 @@ static int __ll_inode_revalidate(struct dentry *dentry, __u64 ibits)
 			goto out;
 		}
 
-		rc = ll_revalidate_it_finish(req, &oit, dentry);
+		rc = ll_revalidate_it_finish(req, &oit, inode);
 		if (rc != 0) {
 			ll_intent_release(&oit);
 			goto out;
@@ -2944,7 +2944,7 @@ static int __ll_inode_revalidate(struct dentry *dentry, __u64 ibits)
 		if (!dentry->d_inode->i_nlink)
 			d_lustre_invalidate(dentry, 0);
 
-		ll_lookup_finish_locks(&oit, dentry);
+		ll_lookup_finish_locks(&oit, inode);
 	} else if (!ll_have_md_lock(dentry->d_inode, &ibits, LCK_MINMODE)) {
 		struct ll_sb_info *sbi = ll_i2sbi(dentry->d_inode);
 		u64 valid = OBD_MD_FLGETATTR;

drivers/staging/lustre/lustre/llite/llite_internal.h

@@ -786,9 +786,9 @@ extern const struct dentry_operations ll_d_ops;
 void ll_intent_drop_lock(struct lookup_intent *);
 void ll_intent_release(struct lookup_intent *);
 void ll_invalidate_aliases(struct inode *);
-void ll_lookup_finish_locks(struct lookup_intent *it, struct dentry *dentry);
+void ll_lookup_finish_locks(struct lookup_intent *it, struct inode *inode);
 int ll_revalidate_it_finish(struct ptlrpc_request *request,
-			    struct lookup_intent *it, struct dentry *de);
+			    struct lookup_intent *it, struct inode *inode);
 
 /* llite/llite_lib.c */
 extern struct super_operations lustre_super_operations;

drivers/staging/lustre/lustre/llite/namei.c

@@ -481,6 +481,7 @@ static struct dentry *ll_lookup_it(struct inode *parent, struct dentry *dentry,
 	struct lookup_intent lookup_it = { .it_op = IT_LOOKUP };
 	struct dentry *save = dentry, *retval;
 	struct ptlrpc_request *req = NULL;
+	struct inode *inode;
 	struct md_op_data *op_data;
 	__u32 opc;
 	int rc;
@@ -539,12 +540,13 @@ static struct dentry *ll_lookup_it(struct inode *parent, struct dentry *dentry,
 		goto out;
 	}
 
-	if ((it->it_op & IT_OPEN) && dentry->d_inode &&
-	    !S_ISREG(dentry->d_inode->i_mode) &&
-	    !S_ISDIR(dentry->d_inode->i_mode)) {
-		ll_release_openhandle(dentry->d_inode, it);
+	inode = dentry->d_inode;
+	if ((it->it_op & IT_OPEN) && inode &&
+	    !S_ISREG(inode->i_mode) &&
+	    !S_ISDIR(inode->i_mode)) {
+		ll_release_openhandle(inode, it);
 	}
-	ll_lookup_finish_locks(it, dentry);
+	ll_lookup_finish_locks(it, inode);
 
 	if (dentry == save)
 		retval = NULL;

fs/9p/vfs_inode.c

@@ -1127,7 +1127,7 @@ static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
 	}
 
 	/* Write all dirty data */
-	if (S_ISREG(dentry->d_inode->i_mode))
+	if (d_is_reg(dentry))
 		filemap_write_and_wait(dentry->d_inode->i_mapping);
 
 	retval = p9_client_wstat(fid, &wstat);

fs/aio.c

@@ -1285,7 +1285,7 @@ SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
 
 	ret = -EINVAL;
 	if (unlikely(ctx || nr_events == 0)) {
-		pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
+		pr_debug("EINVAL: ctx %lu nr_events %u\n",
 		         ctx, nr_events);
 		goto out;
 	}
@@ -1333,7 +1333,7 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
 
 		return ret;
 	}
-	pr_debug("EINVAL: io_destroy: invalid context id\n");
+	pr_debug("EINVAL: invalid context id\n");
 	return -EINVAL;
 }
 
@@ -1515,7 +1515,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	    (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
 	    ((ssize_t)iocb->aio_nbytes < 0)
 	   )) {
-		pr_debug("EINVAL: io_submit: overflow check\n");
+		pr_debug("EINVAL: overflow check\n");
 		return -EINVAL;
 	}
 

fs/autofs4/dev-ioctl.c

@@ -95,7 +95,7 @@ static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  */
 static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
 {
-	struct autofs_dev_ioctl tmp;
+	struct autofs_dev_ioctl tmp, *res;
 
 	if (copy_from_user(&tmp, in, sizeof(tmp)))
 		return ERR_PTR(-EFAULT);
@@ -106,7 +106,11 @@ static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *i
 	if (tmp.size > (PATH_MAX + sizeof(tmp)))
 		return ERR_PTR(-ENAMETOOLONG);
 
-	return memdup_user(in, tmp.size);
+	res = memdup_user(in, tmp.size);
+	if (!IS_ERR(res))
+		res->size = tmp.size;
+
+	return res;
 }
 
 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)

fs/autofs4/expire.c

@@ -374,7 +374,7 @@ static struct dentry *should_expire(struct dentry *dentry,
 		return NULL;
 	}
 
-	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
+	if (dentry->d_inode && d_is_symlink(dentry)) {
 		DPRINTK("checking symlink %p %pd", dentry, dentry);
 		/*
 		 * A symlink can't be "busy" in the usual sense so

fs/autofs4/root.c

@@ -108,7 +108,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 	struct dentry *dentry = file->f_path.dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 
-	DPRINTK("file=%p dentry=%p %pD", file, dentry, dentry);
+	DPRINTK("file=%p dentry=%p %pd", file, dentry, dentry);
 
 	if (autofs4_oz_mode(sbi))
 		goto out;
@@ -371,7 +371,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 	 * having d_mountpoint() true, so there's no need to call back
 	 * to the daemon.
 	 */
-	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
+	if (dentry->d_inode && d_is_symlink(dentry)) {
 		spin_unlock(&sbi->fs_lock);
 		goto done;
 	}
@@ -485,7 +485,7 @@ static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
 		 * an incorrect ELOOP error return.
 		 */
 		if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
-		    (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)))
+		    (dentry->d_inode && d_is_symlink(dentry)))
 			status = -EISDIR;
 	}
 	spin_unlock(&sbi->fs_lock);

fs/bad_inode.c

@@ -15,161 +15,14 @@
 #include <linux/namei.h>
 #include <linux/poll.h>
 
-
-static loff_t bad_file_llseek(struct file *file, loff_t offset, int whence)
-{
-	return -EIO;
-}
-
-static ssize_t bad_file_read(struct file *filp, char __user *buf,
-			size_t size, loff_t *ppos)
-{
-        return -EIO;
-}
-
-static ssize_t bad_file_write(struct file *filp, const char __user *buf,
-			size_t siz, loff_t *ppos)
-{
-        return -EIO;
-}
-
-static ssize_t bad_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
-			unsigned long nr_segs, loff_t pos)
-{
-	return -EIO;
-}
-
-static ssize_t bad_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
-			unsigned long nr_segs, loff_t pos)
-{
-	return -EIO;
-}
-
-static int bad_file_readdir(struct file *file, struct dir_context *ctx)
-{
-	return -EIO;
-}
-
-static unsigned int bad_file_poll(struct file *filp, poll_table *wait)
-{
-	return POLLERR;
-}
-
-static long bad_file_unlocked_ioctl(struct file *file, unsigned cmd,
-			unsigned long arg)
-{
-	return -EIO;
-}
-
-static long bad_file_compat_ioctl(struct file *file, unsigned int cmd,
-			unsigned long arg)
-{
-	return -EIO;
-}
-
-static int bad_file_mmap(struct file *file, struct vm_area_struct *vma)
-{
-	return -EIO;
-}
-
 static int bad_file_open(struct inode *inode, struct file *filp)
 {
 	return -EIO;
 }
 
-static int bad_file_flush(struct file *file, fl_owner_t id)
-{
-	return -EIO;
-}
-
-static int bad_file_release(struct inode *inode, struct file *filp)
-{
-	return -EIO;
-}
-
-static int bad_file_fsync(struct file *file, loff_t start, loff_t end,
-			  int datasync)
-{
-	return -EIO;
-}
-
-static int bad_file_aio_fsync(struct kiocb *iocb, int datasync)
-{
-	return -EIO;
-}
-
-static int bad_file_fasync(int fd, struct file *filp, int on)
-{
-	return -EIO;
-}
-
-static int bad_file_lock(struct file *file, int cmd, struct file_lock *fl)
-{
-	return -EIO;
-}
-
-static ssize_t bad_file_sendpage(struct file *file, struct page *page,
-			int off, size_t len, loff_t *pos, int more)
-{
-	return -EIO;
-}
-
-static unsigned long bad_file_get_unmapped_area(struct file *file,
-				unsigned long addr, unsigned long len,
-				unsigned long pgoff, unsigned long flags)
-{
-	return -EIO;
-}
-
-static int bad_file_check_flags(int flags)
-{
-	return -EIO;
-}
-
-static int bad_file_flock(struct file *filp, int cmd, struct file_lock *fl)
-{
-	return -EIO;
-}
-
-static ssize_t bad_file_splice_write(struct pipe_inode_info *pipe,
-			struct file *out, loff_t *ppos, size_t len,
-			unsigned int flags)
-{
-	return -EIO;
-}
-
-static ssize_t bad_file_splice_read(struct file *in, loff_t *ppos,
-			struct pipe_inode_info *pipe, size_t len,
-			unsigned int flags)
-{
-	return -EIO;
-}
-
 static const struct file_operations bad_file_ops =
 {
-	.llseek		= bad_file_llseek,
-	.read		= bad_file_read,
-	.write		= bad_file_write,
-	.aio_read	= bad_file_aio_read,
-	.aio_write	= bad_file_aio_write,
-	.iterate	= bad_file_readdir,
-	.poll		= bad_file_poll,
-	.unlocked_ioctl	= bad_file_unlocked_ioctl,
-	.compat_ioctl	= bad_file_compat_ioctl,
-	.mmap		= bad_file_mmap,
 	.open		= bad_file_open,
-	.flush		= bad_file_flush,
-	.release	= bad_file_release,
-	.fsync		= bad_file_fsync,
-	.aio_fsync	= bad_file_aio_fsync,
-	.fasync		= bad_file_fasync,
-	.lock		= bad_file_lock,
-	.sendpage	= bad_file_sendpage,
-	.get_unmapped_area = bad_file_get_unmapped_area,
-	.check_flags	= bad_file_check_flags,
-	.flock		= bad_file_flock,
-	.splice_write	= bad_file_splice_write,
-	.splice_read	= bad_file_splice_read,
 };
 
 static int bad_inode_create (struct inode *dir, struct dentry *dentry,

fs/btrfs/ioctl.c

@@ -776,11 +776,11 @@ static int btrfs_may_delete(struct inode *dir, struct dentry *victim, int isdir)
 	    IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
 		return -EPERM;
 	if (isdir) {
-		if (!S_ISDIR(victim->d_inode->i_mode))
+		if (!d_is_dir(victim))
 			return -ENOTDIR;
 		if (IS_ROOT(victim))
 			return -EBUSY;
-	} else if (S_ISDIR(victim->d_inode->i_mode))
+	} else if (d_is_dir(victim))
 		return -EISDIR;
 	if (IS_DEADDIR(dir))
 		return -ENOENT;

fs/cachefiles/daemon.c

@@ -574,7 +574,7 @@ static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
 	/* extract the directory dentry from the cwd */
 	get_fs_pwd(current->fs, &path);
 
-	if (!S_ISDIR(path.dentry->d_inode->i_mode))
+	if (!d_can_lookup(path.dentry))
 		goto notdir;
 
 	cachefiles_begin_secure(cache, &saved_cred);
@@ -646,7 +646,7 @@ static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
 	/* extract the directory dentry from the cwd */
 	get_fs_pwd(current->fs, &path);
 
-	if (!S_ISDIR(path.dentry->d_inode->i_mode))
+	if (!d_can_lookup(path.dentry))
 		goto notdir;
 
 	cachefiles_begin_secure(cache, &saved_cred);

fs/cachefiles/interface.c

@@ -437,7 +437,7 @@ static int cachefiles_attr_changed(struct fscache_object *_object)
 	if (!object->backer)
 		return -ENOBUFS;
 
-	ASSERT(S_ISREG(object->backer->d_inode->i_mode));
+	ASSERT(d_is_reg(object->backer));
 
 	fscache_set_store_limit(&object->fscache, ni_size);
 
@@ -501,7 +501,7 @@ static void cachefiles_invalidate_object(struct fscache_operation *op)
 	       op->object->debug_id, (unsigned long long)ni_size);
 
 	if (object->backer) {
-		ASSERT(S_ISREG(object->backer->d_inode->i_mode));
+		ASSERT(d_is_reg(object->backer));
 
 		fscache_set_store_limit(&object->fscache, ni_size);
 

fs/cachefiles/namei.c

@@ -277,7 +277,7 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache,
 	_debug("remove %p from %p", rep, dir);
 
 	/* non-directories can just be unlinked */
-	if (!S_ISDIR(rep->d_inode->i_mode)) {
+	if (!d_is_dir(rep)) {
 		_debug("unlink stale object");
 
 		path.mnt = cache->mnt;
@@ -323,7 +323,7 @@ try_again:
 		return 0;
 	}
 
-	if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
+	if (!d_can_lookup(cache->graveyard)) {
 		unlock_rename(cache->graveyard, dir);
 		cachefiles_io_error(cache, "Graveyard no longer a directory");
 		return -EIO;
@@ -475,7 +475,7 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 	ASSERT(parent->dentry);
 	ASSERT(parent->dentry->d_inode);
 
-	if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
+	if (!(d_is_dir(parent->dentry))) {
 		// TODO: convert file to dir
 		_leave("looking up in none directory");
 		return -ENOBUFS;
@@ -539,7 +539,7 @@ lookup_again:
 			_debug("mkdir -> %p{%p{ino=%lu}}",
 			       next, next->d_inode, next->d_inode->i_ino);
 
-		} else if (!S_ISDIR(next->d_inode->i_mode)) {
+		} else if (!d_can_lookup(next)) {
 			pr_err("inode %lu is not a directory\n",
 			       next->d_inode->i_ino);
 			ret = -ENOBUFS;
@@ -568,8 +568,8 @@ lookup_again:
 			_debug("create -> %p{%p{ino=%lu}}",
 			       next, next->d_inode, next->d_inode->i_ino);
 
-		} else if (!S_ISDIR(next->d_inode->i_mode) &&
-			   !S_ISREG(next->d_inode->i_mode)
+		} else if (!d_can_lookup(next) &&
+			   !d_is_reg(next)
 			   ) {
 			pr_err("inode %lu is not a file or directory\n",
 			       next->d_inode->i_ino);
@@ -642,7 +642,7 @@ lookup_again:
 
 	/* open a file interface onto a data file */
 	if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
-		if (S_ISREG(object->dentry->d_inode->i_mode)) {
+		if (d_is_reg(object->dentry)) {
 			const struct address_space_operations *aops;
 
 			ret = -EPERM;
@@ -763,7 +763,7 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 	/* we need to make sure the subdir is a directory */
 	ASSERT(subdir->d_inode);
 
-	if (!S_ISDIR(subdir->d_inode->i_mode)) {
+	if (!d_can_lookup(subdir)) {
 		pr_err("%s is not a directory\n", dirname);
 		ret = -EIO;
 		goto check_error;

fs/cachefiles/rdwr.c

@@ -900,7 +900,7 @@ int cachefiles_write_page(struct fscache_storage *op, struct page *page)
 		return -ENOBUFS;
 	}
 
-	ASSERT(S_ISREG(object->backer->d_inode->i_mode));
+	ASSERT(d_is_reg(object->backer));
 
 	cache = container_of(object->fscache.cache,
 			     struct cachefiles_cache, cache);

fs/ceph/dir.c

@@ -904,7 +904,7 @@ static int ceph_unlink(struct inode *dir, struct dentry *dentry)
 	} else if (ceph_snap(dir) == CEPH_NOSNAP) {
 		dout("unlink/rmdir dir %p dn %p inode %p\n",
 		     dir, dentry, inode);
-		op = S_ISDIR(dentry->d_inode->i_mode) ?
+		op = d_is_dir(dentry) ?
 			CEPH_MDS_OP_RMDIR : CEPH_MDS_OP_UNLINK;
 	} else
 		goto out;

fs/ceph/file.c

@@ -292,7 +292,7 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 	}
 	if (err)
 		goto out_req;
-	if (dn || dentry->d_inode == NULL || S_ISLNK(dentry->d_inode->i_mode)) {
+	if (dn || dentry->d_inode == NULL || d_is_symlink(dentry)) {
 		/* make vfs retry on splice, ENOENT, or symlink */
 		dout("atomic_open finish_no_open on dn %p\n", dn);
 		err = finish_no_open(file, dn);

fs/coda/dir.c

@@ -304,7 +304,7 @@ static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
 			     (const char *) old_name, (const char *)new_name);
 	if (!error) {
 		if (new_dentry->d_inode) {
-			if (S_ISDIR(new_dentry->d_inode->i_mode)) {
+			if (d_is_dir(new_dentry)) {
 				coda_dir_drop_nlink(old_dir);
 				coda_dir_inc_nlink(new_dir);
 			}

fs/configfs/configfs_internal.h

@@ -69,14 +69,13 @@ extern struct kmem_cache *configfs_dir_cachep;
 extern int configfs_is_root(struct config_item *item);
 
 extern struct inode * configfs_new_inode(umode_t mode, struct configfs_dirent *, struct super_block *);
-extern int configfs_create(struct dentry *, umode_t mode, int (*init)(struct inode *));
+extern int configfs_create(struct dentry *, umode_t mode, void (*init)(struct inode *));
 
 extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
 extern int configfs_make_dirent(struct configfs_dirent *,
 				struct dentry *, void *, umode_t, int);
 extern int configfs_dirent_is_ready(struct configfs_dirent *);
 
-extern int configfs_add_file(struct dentry *, const struct configfs_attribute *, int);
 extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
 
 extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);

fs/configfs/dir.c

@@ -240,60 +240,26 @@ int configfs_make_dirent(struct configfs_dirent * parent_sd,
 	return 0;
 }
 
-static int init_dir(struct inode * inode)
+static void init_dir(struct inode * inode)
 {
 	inode->i_op = &configfs_dir_inode_operations;
 	inode->i_fop = &configfs_dir_operations;
 
 	/* directory inodes start off with i_nlink == 2 (for "." entry) */
 	inc_nlink(inode);
-	return 0;
 }
 
-static int configfs_init_file(struct inode * inode)
+static void configfs_init_file(struct inode * inode)
 {
 	inode->i_size = PAGE_SIZE;
 	inode->i_fop = &configfs_file_operations;
-	return 0;
 }
 
-static int init_symlink(struct inode * inode)
+static void init_symlink(struct inode * inode)
 {
 	inode->i_op = &configfs_symlink_inode_operations;
-	return 0;
-}
-
-static int create_dir(struct config_item *k, struct dentry *d)
-{
-	int error;
-	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
-	struct dentry *p = d->d_parent;
-
-	BUG_ON(!k);
-
-	error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
-	if (!error)
-		error = configfs_make_dirent(p->d_fsdata, d, k, mode,
-					     CONFIGFS_DIR | CONFIGFS_USET_CREATING);
-	if (!error) {
-		configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
-		error = configfs_create(d, mode, init_dir);
-		if (!error) {
-			inc_nlink(p->d_inode);
-		} else {
-			struct configfs_dirent *sd = d->d_fsdata;
-			if (sd) {
-				spin_lock(&configfs_dirent_lock);
-				list_del_init(&sd->s_sibling);
-				spin_unlock(&configfs_dirent_lock);
-				configfs_put(sd);
-			}
-		}
-	}
-	return error;
 }
 
-
 /**
  *	configfs_create_dir - create a directory for an config_item.
  *	@item:		config_itemwe're creating directory for.
@@ -303,11 +269,37 @@ static int create_dir(struct config_item *k, struct dentry *d)
  *	until it is validated by configfs_dir_set_ready()
  */
 
-static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
+static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
 {
-	int error = create_dir(item, dentry);
-	if (!error)
+	int error;
+	umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
+	struct dentry *p = dentry->d_parent;
+
+	BUG_ON(!item);
+
+	error = configfs_dirent_exists(p->d_fsdata, dentry->d_name.name);
+	if (unlikely(error))
+		return error;
+
+	error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
+				     CONFIGFS_DIR | CONFIGFS_USET_CREATING);
+	if (unlikely(error))
+		return error;
+
+	configfs_set_dir_dirent_depth(p->d_fsdata, dentry->d_fsdata);
+	error = configfs_create(dentry, mode, init_dir);
+	if (!error) {
+		inc_nlink(p->d_inode);
 		item->ci_dentry = dentry;
+	} else {
+		struct configfs_dirent *sd = dentry->d_fsdata;
+		if (sd) {
+			spin_lock(&configfs_dirent_lock);
+			list_del_init(&sd->s_sibling);
+			spin_unlock(&configfs_dirent_lock);
+			configfs_put(sd);
+		}
+	}
 	return error;
 }
 

fs/configfs/file.c

@@ -313,21 +313,6 @@ const struct file_operations configfs_file_operations = {
 	.release	= configfs_release,
 };
 
-
-int configfs_add_file(struct dentry * dir, const struct configfs_attribute * attr, int type)
-{
-	struct configfs_dirent * parent_sd = dir->d_fsdata;
-	umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
-	int error = 0;
-
-	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_NORMAL);
-	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
-	mutex_unlock(&dir->d_inode->i_mutex);
-
-	return error;
-}
-
-
 /**
  *	configfs_create_file - create an attribute file for an item.
  *	@item:	item we're creating for.
@@ -336,9 +321,16 @@ int configfs_add_file(struct dentry * dir, const struct configfs_attribute * att
 
 int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
 {
-	BUG_ON(!item || !item->ci_dentry || !attr);
+	struct dentry *dir = item->ci_dentry;
+	struct configfs_dirent *parent_sd = dir->d_fsdata;
+	umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
+	int error = 0;
 
-	return configfs_add_file(item->ci_dentry, attr,
-				 CONFIGFS_ITEM_ATTR);
+	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_NORMAL);
+	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
+				     CONFIGFS_ITEM_ATTR);
+	mutex_unlock(&dir->d_inode->i_mutex);
+
+	return error;
 }
 

fs/configfs/inode.c

@@ -176,7 +176,7 @@ static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
 
 #endif /* CONFIG_LOCKDEP */
 
-int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct inode *))
+int configfs_create(struct dentry * dentry, umode_t mode, void (*init)(struct inode *))
 {
 	int error = 0;
 	struct inode *inode = NULL;
@@ -198,13 +198,7 @@ int configfs_create(struct dentry * dentry, umode_t mode, int (*init)(struct ino
 	p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
 	configfs_set_inode_lock_class(sd, inode);
 
-	if (init) {
-		error = init(inode);
-		if (error) {
-			iput(inode);
-			return error;
-		}
-	}
+	init(inode);
 	d_instantiate(dentry, inode);
 	if (S_ISDIR(mode) || S_ISLNK(mode))
 		dget(dentry);  /* pin link and directory dentries in core */
@@ -242,7 +236,7 @@ void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 
 	if (dentry) {
 		spin_lock(&dentry->d_lock);
-		if (!(d_unhashed(dentry) && dentry->d_inode)) {
+		if (!d_unhashed(dentry) && dentry->d_inode) {
 			dget_dlock(dentry);
 			__d_drop(dentry);
 			spin_unlock(&dentry->d_lock);

fs/coredump.c

@@ -572,7 +572,7 @@ void do_coredump(const siginfo_t *siginfo)
 			 *
 			 * Normally core limits are irrelevant to pipes, since
 			 * we're not writing to the file system, but we use
-			 * cprm.limit of 1 here as a speacial value, this is a
+			 * cprm.limit of 1 here as a special value, this is a
 			 * consistent way to catch recursive crashes.
 			 * We can still crash if the core_pattern binary sets
 			 * RLIM_CORE = !1, but it runs as root, and can do

fs/dcache.c

@@ -1659,9 +1659,25 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
 }
 EXPORT_SYMBOL(d_set_d_op);
 
+
+/*
+ * d_set_fallthru - Mark a dentry as falling through to a lower layer
+ * @dentry - The dentry to mark
+ *
+ * Mark a dentry as falling through to the lower layer (as set with
+ * d_pin_lower()).  This flag may be recorded on the medium.
+ */
+void d_set_fallthru(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	dentry->d_flags |= DCACHE_FALLTHRU;
+	spin_unlock(&dentry->d_lock);
+}
+EXPORT_SYMBOL(d_set_fallthru);
+
 static unsigned d_flags_for_inode(struct inode *inode)
 {
-	unsigned add_flags = DCACHE_FILE_TYPE;
+	unsigned add_flags = DCACHE_REGULAR_TYPE;
 
 	if (!inode)
 		return DCACHE_MISS_TYPE;
@@ -1674,13 +1690,21 @@ static unsigned d_flags_for_inode(struct inode *inode)
 			else
 				inode->i_opflags |= IOP_LOOKUP;
 		}
-	} else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
-		if (unlikely(inode->i_op->follow_link))
+		goto type_determined;
+	}
+
+	if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
+		if (unlikely(inode->i_op->follow_link)) {
 			add_flags = DCACHE_SYMLINK_TYPE;
-		else
-			inode->i_opflags |= IOP_NOFOLLOW;
+			goto type_determined;
+		}
+		inode->i_opflags |= IOP_NOFOLLOW;
 	}
 
+	if (unlikely(!S_ISREG(inode->i_mode)))
+		add_flags = DCACHE_SPECIAL_TYPE;
+
+type_determined:
 	if (unlikely(IS_AUTOMOUNT(inode)))
 		add_flags |= DCACHE_NEED_AUTOMOUNT;
 	return add_flags;
@@ -1691,7 +1715,8 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 	unsigned add_flags = d_flags_for_inode(inode);
 
 	spin_lock(&dentry->d_lock);
-	__d_set_type(dentry, add_flags);
+	dentry->d_flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
+	dentry->d_flags |= add_flags;
 	if (inode)
 		hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
 	dentry->d_inode = inode;

fs/debugfs/inode.c

@@ -169,10 +169,19 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root)
 	return 0;
 }
 
+static void debugfs_evict_inode(struct inode *inode)
+{
+	truncate_inode_pages_final(&inode->i_data);
+	clear_inode(inode);
+	if (S_ISLNK(inode->i_mode))
+		kfree(inode->i_private);
+}
+
 static const struct super_operations debugfs_super_operations = {
 	.statfs		= simple_statfs,
 	.remount_fs	= debugfs_remount,
 	.show_options	= debugfs_show_options,
+	.evict_inode	= debugfs_evict_inode,
 };
 
 static struct vfsmount *debugfs_automount(struct path *path)
@@ -511,23 +520,14 @@ static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
 	int ret = 0;
 
 	if (debugfs_positive(dentry)) {
-		if (dentry->d_inode) {
-			dget(dentry);
-			switch (dentry->d_inode->i_mode & S_IFMT) {
-			case S_IFDIR:
-				ret = simple_rmdir(parent->d_inode, dentry);
-				break;
-			case S_IFLNK:
-				kfree(dentry->d_inode->i_private);
-				/* fall through */
-			default:
-				simple_unlink(parent->d_inode, dentry);
-				break;
-			}
-			if (!ret)
-				d_delete(dentry);
-			dput(dentry);
-		}
+		dget(dentry);
+		if (S_ISDIR(dentry->d_inode->i_mode))
+			ret = simple_rmdir(parent->d_inode, dentry);
+		else
+			simple_unlink(parent->d_inode, dentry);
+		if (!ret)
+			d_delete(dentry);
+		dput(dentry);
 	}
 	return ret;
 }
@@ -690,7 +690,7 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
 	}
 	d_move(old_dentry, dentry);
 	fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
-		S_ISDIR(old_dentry->d_inode->i_mode),
+		d_is_dir(old_dentry),
 		NULL, old_dentry);
 	fsnotify_oldname_free(old_name);
 	unlock_rename(new_dir, old_dir);

fs/ecryptfs/file.c

@@ -230,7 +230,7 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
 	}
 	ecryptfs_set_file_lower(
 		file, ecryptfs_inode_to_private(inode)->lower_file);
-	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
+	if (d_is_dir(ecryptfs_dentry)) {
 		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 		mutex_lock(&crypt_stat->cs_mutex);
 		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);

fs/ecryptfs/inode.c

@@ -907,9 +907,9 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 	lower_inode = ecryptfs_inode_to_lower(inode);
 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
 	mutex_lock(&crypt_stat->cs_mutex);
-	if (S_ISDIR(dentry->d_inode->i_mode))
+	if (d_is_dir(dentry))
 		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
-	else if (S_ISREG(dentry->d_inode->i_mode)
+	else if (d_is_reg(dentry)
 		 && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
 		     || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
 		struct ecryptfs_mount_crypt_stat *mount_crypt_stat;

fs/exportfs/expfs.c

@@ -429,7 +429,7 @@ struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 	if (IS_ERR(result))
 		return result;
 
-	if (S_ISDIR(result->d_inode->i_mode)) {
+	if (d_is_dir(result)) {
 		/*
 		 * This request is for a directory.
 		 *

fs/fs-writeback.c

@@ -769,9 +769,9 @@ static long __writeback_inodes_wb(struct bdi_writeback *wb,
 		struct inode *inode = wb_inode(wb->b_io.prev);
 		struct super_block *sb = inode->i_sb;
 
-		if (!grab_super_passive(sb)) {
+		if (!trylock_super(sb)) {
 			/*
-			 * grab_super_passive() may fail consistently due to
+			 * trylock_super() may fail consistently due to
 			 * s_umount being grabbed by someone else. Don't use
 			 * requeue_io() to avoid busy retrying the inode/sb.
 			 */
@@ -779,7 +779,7 @@ static long __writeback_inodes_wb(struct bdi_writeback *wb,
 			continue;
 		}
 		wrote += writeback_sb_inodes(sb, wb, work);
-		drop_super(sb);
+		up_read(&sb->s_umount);
 
 		/* refer to the same tests at the end of writeback_sb_inodes */
 		if (wrote) {

fs/fuse/dir.c

@@ -971,7 +971,7 @@ int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
 			err = -EBUSY;
 			goto badentry;
 		}
-		if (S_ISDIR(entry->d_inode->i_mode)) {
+		if (d_is_dir(entry)) {
 			shrink_dcache_parent(entry);
 			if (!simple_empty(entry)) {
 				err = -ENOTEMPTY;

fs/gfs2/dir.c

@@ -1809,7 +1809,7 @@ int gfs2_dir_del(struct gfs2_inode *dip, const struct dentry *dentry)
 		gfs2_consist_inode(dip);
 	dip->i_entries--;
 	dip->i_inode.i_mtime = dip->i_inode.i_ctime = tv;
-	if (S_ISDIR(dentry->d_inode->i_mode))
+	if (d_is_dir(dentry))
 		drop_nlink(&dip->i_inode);
 	mark_inode_dirty(&dip->i_inode);
 

fs/hfsplus/dir.c

@@ -530,7 +530,7 @@ static int hfsplus_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 	/* Unlink destination if it already exists */
 	if (new_dentry->d_inode) {
-		if (S_ISDIR(new_dentry->d_inode->i_mode))
+		if (d_is_dir(new_dentry))
 			res = hfsplus_rmdir(new_dir, new_dentry);
 		else
 			res = hfsplus_unlink(new_dir, new_dentry);

fs/hppfs/hppfs.c

@@ -678,10 +678,10 @@ static struct inode *get_inode(struct super_block *sb, struct dentry *dentry)
 		return NULL;
 	}
 
-	if (S_ISDIR(dentry->d_inode->i_mode)) {
+	if (d_is_dir(dentry)) {
 		inode->i_op = &hppfs_dir_iops;
 		inode->i_fop = &hppfs_dir_fops;
-	} else if (S_ISLNK(dentry->d_inode->i_mode)) {
+	} else if (d_is_symlink(dentry)) {
 		inode->i_op = &hppfs_link_iops;
 		inode->i_fop = &hppfs_file_fops;
 	} else {

fs/internal.h

@@ -84,7 +84,7 @@ extern struct file *get_empty_filp(void);
  * super.c
  */
 extern int do_remount_sb(struct super_block *, int, void *, int);
-extern bool grab_super_passive(struct super_block *sb);
+extern bool trylock_super(struct super_block *sb);
 extern struct dentry *mount_fs(struct file_system_type *,
 			       int, const char *, void *);
 extern struct super_block *user_get_super(dev_t);

fs/jffs2/dir.c

@@ -252,7 +252,7 @@ static int jffs2_link (struct dentry *old_dentry, struct inode *dir_i, struct de
 	if (!f->inocache)
 		return -EIO;
 
-	if (S_ISDIR(old_dentry->d_inode->i_mode))
+	if (d_is_dir(old_dentry))
 		return -EPERM;
 
 	/* XXX: This is ugly */
@@ -772,7 +772,7 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 	 */
 	if (new_dentry->d_inode) {
 		victim_f = JFFS2_INODE_INFO(new_dentry->d_inode);
-		if (S_ISDIR(new_dentry->d_inode->i_mode)) {
+		if (d_is_dir(new_dentry)) {
 			struct jffs2_full_dirent *fd;
 
 			mutex_lock(&victim_f->sem);
@@ -807,7 +807,7 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 
 	if (victim_f) {
 		/* There was a victim. Kill it off nicely */
-		if (S_ISDIR(new_dentry->d_inode->i_mode))
+		if (d_is_dir(new_dentry))
 			clear_nlink(new_dentry->d_inode);
 		else
 			drop_nlink(new_dentry->d_inode);
@@ -815,7 +815,7 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 		   inode which didn't exist. */
 		if (victim_f->inocache) {
 			mutex_lock(&victim_f->sem);
-			if (S_ISDIR(new_dentry->d_inode->i_mode))
+			if (d_is_dir(new_dentry))
 				victim_f->inocache->pino_nlink = 0;
 			else
 				victim_f->inocache->pino_nlink--;
@@ -825,7 +825,7 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 
 	/* If it was a directory we moved, and there was no victim,
 	   increase i_nlink on its new parent */
-	if (S_ISDIR(old_dentry->d_inode->i_mode) && !victim_f)
+	if (d_is_dir(old_dentry) && !victim_f)
 		inc_nlink(new_dir_i);
 
 	/* Unlink the original */
@@ -839,7 +839,7 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 		struct jffs2_inode_info *f = JFFS2_INODE_INFO(old_dentry->d_inode);
 		mutex_lock(&f->sem);
 		inc_nlink(old_dentry->d_inode);
-		if (f->inocache && !S_ISDIR(old_dentry->d_inode->i_mode))
+		if (f->inocache && !d_is_dir(old_dentry))
 			f->inocache->pino_nlink++;
 		mutex_unlock(&f->sem);
 
@@ -852,7 +852,7 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 		return ret;
 	}
 
-	if (S_ISDIR(old_dentry->d_inode->i_mode))
+	if (d_is_dir(old_dentry))
 		drop_nlink(old_dir_i);
 
 	new_dir_i->i_mtime = new_dir_i->i_ctime = old_dir_i->i_mtime = old_dir_i->i_ctime = ITIME(now);

fs/jffs2/super.c

@@ -138,7 +138,7 @@ static struct dentry *jffs2_get_parent(struct dentry *child)
 	struct jffs2_inode_info *f;
 	uint32_t pino;
 
-	BUG_ON(!S_ISDIR(child->d_inode->i_mode));
+	BUG_ON(!d_is_dir(child));
 
 	f = JFFS2_INODE_INFO(child->d_inode);
 

fs/libfs.c

@@ -329,7 +329,7 @@ int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
 		struct inode *new_dir, struct dentry *new_dentry)
 {
 	struct inode *inode = old_dentry->d_inode;
-	int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
+	int they_are_dirs = d_is_dir(old_dentry);
 
 	if (!simple_empty(new_dentry))
 		return -ENOTEMPTY;

fs/namei.c

@@ -2814,7 +2814,7 @@ no_open:
 			} else if (!dentry->d_inode) {
 				goto out;
 			} else if ((open_flag & O_TRUNC) &&
-				   S_ISREG(dentry->d_inode->i_mode)) {
+				   d_is_reg(dentry)) {
 				goto out;
 			}
 			/* will fail later, go on to get the right error */

fs/namespace.c

@@ -1907,8 +1907,8 @@ static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)
 	if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER)
 		return -EINVAL;
 
-	if (S_ISDIR(mp->m_dentry->d_inode->i_mode) !=
-	      S_ISDIR(mnt->mnt.mnt_root->d_inode->i_mode))
+	if (d_is_dir(mp->m_dentry) !=
+	      d_is_dir(mnt->mnt.mnt_root))
 		return -ENOTDIR;
 
 	return attach_recursive_mnt(mnt, p, mp, NULL);
@@ -2180,8 +2180,8 @@ static int do_move_mount(struct path *path, const char *old_name)
 	if (!mnt_has_parent(old))
 		goto out1;
 
-	if (S_ISDIR(path->dentry->d_inode->i_mode) !=
-	      S_ISDIR(old_path.dentry->d_inode->i_mode))
+	if (d_is_dir(path->dentry) !=
+	      d_is_dir(old_path.dentry))
 		goto out1;
 	/*
 	 * Don't move a mount residing in a shared parent.
@@ -2271,7 +2271,7 @@ static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
 		goto unlock;
 
 	err = -EINVAL;
-	if (S_ISLNK(newmnt->mnt.mnt_root->d_inode->i_mode))
+	if (d_is_symlink(newmnt->mnt.mnt_root))
 		goto unlock;
 
 	newmnt->mnt.mnt_flags = mnt_flags;

fs/nfsd/nfs4recover.c

@@ -583,7 +583,7 @@ nfs4_reset_recoverydir(char *recdir)
 	if (status)
 		return status;
 	status = -ENOTDIR;
-	if (S_ISDIR(path.dentry->d_inode->i_mode)) {
+	if (d_is_dir(path.dentry)) {
 		strcpy(user_recovery_dirname, recdir);
 		status = 0;
 	}
@@ -1426,7 +1426,7 @@ nfsd4_client_tracking_init(struct net *net)
 	nn->client_tracking_ops = &nfsd4_legacy_tracking_ops;
 	status = kern_path(nfs4_recoverydir(), LOOKUP_FOLLOW, &path);
 	if (!status) {
-		status = S_ISDIR(path.dentry->d_inode->i_mode);
+		status = d_is_dir(path.dentry);
 		path_put(&path);
 		if (status)
 			goto do_init;

fs/nfsd/nfsfh.c

@@ -114,8 +114,8 @@ static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
 	 * We're exposing only the directories and symlinks that have to be
 	 * traversed on the way to real exports:
 	 */
-	if (unlikely(!S_ISDIR(dentry->d_inode->i_mode) &&
-		     !S_ISLNK(dentry->d_inode->i_mode)))
+	if (unlikely(!d_is_dir(dentry) &&
+		     !d_is_symlink(dentry)))
 		return nfserr_stale;
 	/*
 	 * A pseudoroot export gives permission to access only one
@@ -259,7 +259,7 @@ static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
 		goto out;
 	}
 
-	if (S_ISDIR(dentry->d_inode->i_mode) &&
+	if (d_is_dir(dentry) &&
 			(dentry->d_flags & DCACHE_DISCONNECTED)) {
 		printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
 				dentry);
@@ -414,7 +414,7 @@ static inline void _fh_update_old(struct dentry *dentry,
 {
 	fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
 	fh->ofh_generation = dentry->d_inode->i_generation;
-	if (S_ISDIR(dentry->d_inode->i_mode) ||
+	if (d_is_dir(dentry) ||
 	    (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
 		fh->ofh_dirino = 0;
 }

fs/nfsd/vfs.c

@@ -615,9 +615,9 @@ nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *suppor
 	export = fhp->fh_export;
 	dentry = fhp->fh_dentry;
 
-	if (S_ISREG(dentry->d_inode->i_mode))
+	if (d_is_reg(dentry))
 		map = nfs3_regaccess;
-	else if (S_ISDIR(dentry->d_inode->i_mode))
+	else if (d_is_dir(dentry))
 		map = nfs3_diraccess;
 	else
 		map = nfs3_anyaccess;
@@ -1402,7 +1402,7 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
 		switch (createmode) {
 		case NFS3_CREATE_UNCHECKED:
-			if (! S_ISREG(dchild->d_inode->i_mode))
+			if (! d_is_reg(dchild))
 				goto out;
 			else if (truncp) {
 				/* in nfsv4, we need to treat this case a little
@@ -1615,7 +1615,7 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 	if (err)
 		goto out;
 	err = nfserr_isdir;
-	if (S_ISDIR(tfhp->fh_dentry->d_inode->i_mode))
+	if (d_is_dir(tfhp->fh_dentry))
 		goto out;
 	err = nfserr_perm;
 	if (!len)

fs/notify/fanotify/fanotify.c

@@ -115,8 +115,8 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
 		return false;
 
 	/* sorry, fanotify only gives a damn about files and dirs */
-	if (!S_ISREG(path->dentry->d_inode->i_mode) &&
-	    !S_ISDIR(path->dentry->d_inode->i_mode))
+	if (!d_is_reg(path->dentry) &&
+	    !d_can_lookup(path->dentry))
 		return false;
 
 	if (inode_mark && vfsmnt_mark) {
@@ -139,7 +139,7 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
 		BUG();
 	}
 
-	if (S_ISDIR(path->dentry->d_inode->i_mode) &&
+	if (d_is_dir(path->dentry) &&
 	    !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
 		return false;
 

fs/overlayfs/copy_up.c

@@ -191,7 +191,6 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 		ovl_set_timestamps(upperdentry, stat);
 
 	return err;
-
 }
 
 static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
@@ -385,7 +384,7 @@ int ovl_copy_up(struct dentry *dentry)
 		struct kstat stat;
 		enum ovl_path_type type = ovl_path_type(dentry);
 
-		if (type != OVL_PATH_LOWER)
+		if (OVL_TYPE_UPPER(type))
 			break;
 
 		next = dget(dentry);
@@ -394,7 +393,7 @@ int ovl_copy_up(struct dentry *dentry)
 			parent = dget_parent(next);
 
 			type = ovl_path_type(parent);
-			if (type != OVL_PATH_LOWER)
+			if (OVL_TYPE_UPPER(type))
 				break;
 
 			dput(next);

fs/overlayfs/dir.c

@@ -19,7 +19,7 @@ void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
 	int err;
 
 	dget(wdentry);
-	if (S_ISDIR(wdentry->d_inode->i_mode))
+	if (d_is_dir(wdentry))
 		err = ovl_do_rmdir(wdir, wdentry);
 	else
 		err = ovl_do_unlink(wdir, wdentry);
@@ -118,14 +118,14 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
 
 static int ovl_set_opaque(struct dentry *upperdentry)
 {
-	return ovl_do_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
+	return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
 }
 
 static void ovl_remove_opaque(struct dentry *upperdentry)
 {
 	int err;
 
-	err = ovl_do_removexattr(upperdentry, ovl_opaque_xattr);
+	err = ovl_do_removexattr(upperdentry, OVL_XATTR_OPAQUE);
 	if (err) {
 		pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
 			upperdentry->d_name.name, err);
@@ -152,7 +152,7 @@ static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
 	 * correct link count.  nlink=1 seems to pacify 'find' and
 	 * other utilities.
 	 */
-	if (type == OVL_PATH_MERGE)
+	if (OVL_TYPE_MERGE(type))
 		stat->nlink = 1;
 
 	return 0;
@@ -506,7 +506,7 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
 	struct dentry *opaquedir = NULL;
 	int err;
 
-	if (is_dir) {
+	if (is_dir && OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
 		opaquedir = ovl_check_empty_and_clear(dentry);
 		err = PTR_ERR(opaquedir);
 		if (IS_ERR(opaquedir))
@@ -630,7 +630,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 		goto out_drop_write;
 
 	type = ovl_path_type(dentry);
-	if (type == OVL_PATH_PURE_UPPER) {
+	if (OVL_TYPE_PURE_UPPER(type)) {
 		err = ovl_remove_upper(dentry, is_dir);
 	} else {
 		const struct cred *old_cred;
@@ -693,7 +693,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
 	bool new_create = false;
 	bool cleanup_whiteout = false;
 	bool overwrite = !(flags & RENAME_EXCHANGE);
-	bool is_dir = S_ISDIR(old->d_inode->i_mode);
+	bool is_dir = d_is_dir(old);
 	bool new_is_dir = false;
 	struct dentry *opaquedir = NULL;
 	const struct cred *old_cred = NULL;
@@ -712,7 +712,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
 	/* Don't copy up directory trees */
 	old_type = ovl_path_type(old);
 	err = -EXDEV;
-	if ((old_type == OVL_PATH_LOWER || old_type == OVL_PATH_MERGE) && is_dir)
+	if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
 		goto out;
 
 	if (new->d_inode) {
@@ -720,30 +720,30 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
 		if (err)
 			goto out;
 
-		if (S_ISDIR(new->d_inode->i_mode))
+		if (d_is_dir(new))
 			new_is_dir = true;
 
 		new_type = ovl_path_type(new);
 		err = -EXDEV;
-		if (!overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir)
+		if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
 			goto out;
 
 		err = 0;
-		if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
+		if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
 			if (ovl_dentry_lower(old)->d_inode ==
 			    ovl_dentry_lower(new)->d_inode)
 				goto out;
 		}
-		if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
+		if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
 			if (ovl_dentry_upper(old)->d_inode ==
 			    ovl_dentry_upper(new)->d_inode)
 				goto out;
 		}
 	} else {
 		if (ovl_dentry_is_opaque(new))
-			new_type = OVL_PATH_UPPER;
+			new_type = __OVL_PATH_UPPER;
 		else
-			new_type = OVL_PATH_PURE_UPPER;
+			new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
 	}
 
 	err = ovl_want_write(old);
@@ -763,8 +763,8 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
 			goto out_drop_write;
 	}
 
-	old_opaque = old_type != OVL_PATH_PURE_UPPER;
-	new_opaque = new_type != OVL_PATH_PURE_UPPER;
+	old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
+	new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
 
 	if (old_opaque || new_opaque) {
 		err = -ENOMEM;
@@ -787,7 +787,7 @@ static int ovl_rename2(struct inode *olddir, struct dentry *old,
 		old_cred = override_creds(override_cred);
 	}
 
-	if (overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir) {
+	if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
 		opaquedir = ovl_check_empty_and_clear(new);
 		err = PTR_ERR(opaquedir);
 		if (IS_ERR(opaquedir)) {

fs/overlayfs/inode.c

@@ -205,7 +205,7 @@ static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
 
 static bool ovl_is_private_xattr(const char *name)
 {
-	return strncmp(name, "trusted.overlay.", 14) == 0;
+	return strncmp(name, OVL_XATTR_PRE_NAME, OVL_XATTR_PRE_LEN) == 0;
 }
 
 int ovl_setxattr(struct dentry *dentry, const char *name,
@@ -238,7 +238,10 @@ out:
 static bool ovl_need_xattr_filter(struct dentry *dentry,
 				  enum ovl_path_type type)
 {
-	return type == OVL_PATH_UPPER && S_ISDIR(dentry->d_inode->i_mode);
+	if ((type & (__OVL_PATH_PURE | __OVL_PATH_UPPER)) == __OVL_PATH_UPPER)
+		return S_ISDIR(dentry->d_inode->i_mode);
+	else
+		return false;
 }
 
 ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
@@ -299,7 +302,7 @@ int ovl_removexattr(struct dentry *dentry, const char *name)
 	if (ovl_need_xattr_filter(dentry, type) && ovl_is_private_xattr(name))
 		goto out_drop_write;
 
-	if (type == OVL_PATH_LOWER) {
+	if (!OVL_TYPE_UPPER(type)) {
 		err = vfs_getxattr(realpath.dentry, name, NULL, 0);
 		if (err < 0)
 			goto out_drop_write;
@@ -321,7 +324,7 @@ out:
 static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
 				  struct dentry *realdentry)
 {
-	if (type != OVL_PATH_LOWER)
+	if (OVL_TYPE_UPPER(type))
 		return false;
 
 	if (special_file(realdentry->d_inode->i_mode))
@@ -430,5 +433,4 @@ struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
 	}
 
 	return inode;
-
 }

fs/overlayfs/overlayfs.h

@@ -12,13 +12,20 @@
 struct ovl_entry;
 
 enum ovl_path_type {
-	OVL_PATH_PURE_UPPER,
-	OVL_PATH_UPPER,
-	OVL_PATH_MERGE,
-	OVL_PATH_LOWER,
+	__OVL_PATH_PURE		= (1 << 0),
+	__OVL_PATH_UPPER	= (1 << 1),
+	__OVL_PATH_MERGE	= (1 << 2),
 };
 
-extern const char *ovl_opaque_xattr;
+#define OVL_TYPE_UPPER(type)	((type) & __OVL_PATH_UPPER)
+#define OVL_TYPE_MERGE(type)	((type) & __OVL_PATH_MERGE)
+#define OVL_TYPE_PURE_UPPER(type) ((type) & __OVL_PATH_PURE)
+#define OVL_TYPE_MERGE_OR_LOWER(type) \
+	(OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type))
+
+#define OVL_XATTR_PRE_NAME "trusted.overlay."
+#define OVL_XATTR_PRE_LEN  16
+#define OVL_XATTR_OPAQUE   OVL_XATTR_PRE_NAME"opaque"
 
 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
 {
@@ -130,6 +137,7 @@ void ovl_dentry_version_inc(struct dentry *dentry);
 void ovl_path_upper(struct dentry *dentry, struct path *path);
 void ovl_path_lower(struct dentry *dentry, struct path *path);
 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
+int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
 struct dentry *ovl_dentry_upper(struct dentry *dentry);
 struct dentry *ovl_dentry_lower(struct dentry *dentry);
 struct dentry *ovl_dentry_real(struct dentry *dentry);

fs/overlayfs/readdir.c

@@ -24,7 +24,6 @@ struct ovl_cache_entry {
 	struct list_head l_node;
 	struct rb_node node;
 	bool is_whiteout;
-	bool is_cursor;
 	char name[];
 };
 
@@ -40,6 +39,7 @@ struct ovl_readdir_data {
 	struct rb_root root;
 	struct list_head *list;
 	struct list_head middle;
+	struct dentry *dir;
 	int count;
 	int err;
 };
@@ -48,7 +48,7 @@ struct ovl_dir_file {
 	bool is_real;
 	bool is_upper;
 	struct ovl_dir_cache *cache;
-	struct ovl_cache_entry cursor;
+	struct list_head *cursor;
 	struct file *realfile;
 	struct file *upperfile;
 };
@@ -79,23 +79,49 @@ static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
 	return NULL;
 }
 
-static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
+static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir,
+						   const char *name, int len,
 						   u64 ino, unsigned int d_type)
 {
 	struct ovl_cache_entry *p;
 	size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
 
 	p = kmalloc(size, GFP_KERNEL);
-	if (p) {
-		memcpy(p->name, name, len);
-		p->name[len] = '\0';
-		p->len = len;
-		p->type = d_type;
-		p->ino = ino;
-		p->is_whiteout = false;
-		p->is_cursor = false;
-	}
+	if (!p)
+		return NULL;
+
+	memcpy(p->name, name, len);
+	p->name[len] = '\0';
+	p->len = len;
+	p->type = d_type;
+	p->ino = ino;
+	p->is_whiteout = false;
+
+	if (d_type == DT_CHR) {
+		struct dentry *dentry;
+		const struct cred *old_cred;
+		struct cred *override_cred;
+
+		override_cred = prepare_creds();
+		if (!override_cred) {
+			kfree(p);
+			return NULL;
+		}
+
+		/*
+		 * CAP_DAC_OVERRIDE for lookup
+		 */
+		cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+		old_cred = override_creds(override_cred);
 
+		dentry = lookup_one_len(name, dir, len);
+		if (!IS_ERR(dentry)) {
+			p->is_whiteout = ovl_is_whiteout(dentry);
+			dput(dentry);
+		}
+		revert_creds(old_cred);
+		put_cred(override_cred);
+	}
 	return p;
 }
 
@@ -122,7 +148,7 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
 			return 0;
 	}
 
-	p = ovl_cache_entry_new(name, len, ino, d_type);
+	p = ovl_cache_entry_new(rdd->dir, name, len, ino, d_type);
 	if (p == NULL)
 		return -ENOMEM;
 
@@ -143,7 +169,7 @@ static int ovl_fill_lower(struct ovl_readdir_data *rdd,
 	if (p) {
 		list_move_tail(&p->l_node, &rdd->middle);
 	} else {
-		p = ovl_cache_entry_new(name, namelen, ino, d_type);
+		p = ovl_cache_entry_new(rdd->dir, name, namelen, ino, d_type);
 		if (p == NULL)
 			rdd->err = -ENOMEM;
 		else
@@ -168,7 +194,6 @@ static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry)
 {
 	struct ovl_dir_cache *cache = od->cache;
 
-	list_del_init(&od->cursor.l_node);
 	WARN_ON(cache->refcount <= 0);
 	cache->refcount--;
 	if (!cache->refcount) {
@@ -204,6 +229,7 @@ static inline int ovl_dir_read(struct path *realpath,
 	if (IS_ERR(realfile))
 		return PTR_ERR(realfile);
 
+	rdd->dir = realpath->dentry;
 	rdd->ctx.pos = 0;
 	do {
 		rdd->count = 0;
@@ -227,108 +253,58 @@ static void ovl_dir_reset(struct file *file)
 	if (cache && ovl_dentry_version_get(dentry) != cache->version) {
 		ovl_cache_put(od, dentry);
 		od->cache = NULL;
+		od->cursor = NULL;
 	}
-	WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
-	if (od->is_real && type == OVL_PATH_MERGE)
+	WARN_ON(!od->is_real && !OVL_TYPE_MERGE(type));
+	if (od->is_real && OVL_TYPE_MERGE(type))
 		od->is_real = false;
 }
 
-static int ovl_dir_mark_whiteouts(struct dentry *dir,
-				  struct ovl_readdir_data *rdd)
-{
-	struct ovl_cache_entry *p;
-	struct dentry *dentry;
-	const struct cred *old_cred;
-	struct cred *override_cred;
-
-	override_cred = prepare_creds();
-	if (!override_cred) {
-		ovl_cache_free(rdd->list);
-		return -ENOMEM;
-	}
-
-	/*
-	 * CAP_DAC_OVERRIDE for lookup
-	 */
-	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
-	old_cred = override_creds(override_cred);
-
-	mutex_lock(&dir->d_inode->i_mutex);
-	list_for_each_entry(p, rdd->list, l_node) {
-		if (p->is_cursor)
-			continue;
-
-		if (p->type != DT_CHR)
-			continue;
-
-		dentry = lookup_one_len(p->name, dir, p->len);
-		if (IS_ERR(dentry))
-			continue;
-
-		p->is_whiteout = ovl_is_whiteout(dentry);
-		dput(dentry);
-	}
-	mutex_unlock(&dir->d_inode->i_mutex);
-
-	revert_creds(old_cred);
-	put_cred(override_cred);
-
-	return 0;
-}
-
 static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list)
 {
 	int err;
-	struct path lowerpath;
-	struct path upperpath;
+	struct path realpath;
 	struct ovl_readdir_data rdd = {
 		.ctx.actor = ovl_fill_merge,
 		.list = list,
 		.root = RB_ROOT,
 		.is_merge = false,
 	};
+	int idx, next;
 
-	ovl_path_lower(dentry, &lowerpath);
-	ovl_path_upper(dentry, &upperpath);
+	for (idx = 0; idx != -1; idx = next) {
+		next = ovl_path_next(idx, dentry, &realpath);
 
-	if (upperpath.dentry) {
-		err = ovl_dir_read(&upperpath, &rdd);
-		if (err)
-			goto out;
-
-		if (lowerpath.dentry) {
-			err = ovl_dir_mark_whiteouts(upperpath.dentry, &rdd);
+		if (next != -1) {
+			err = ovl_dir_read(&realpath, &rdd);
 			if (err)
-				goto out;
+				break;
+		} else {
+			/*
+			 * Insert lowest layer entries before upper ones, this
+			 * allows offsets to be reasonably constant
+			 */
+			list_add(&rdd.middle, rdd.list);
+			rdd.is_merge = true;
+			err = ovl_dir_read(&realpath, &rdd);
+			list_del(&rdd.middle);
 		}
 	}
-	if (lowerpath.dentry) {
-		/*
-		 * Insert lowerpath entries before upperpath ones, this allows
-		 * offsets to be reasonably constant
-		 */
-		list_add(&rdd.middle, rdd.list);
-		rdd.is_merge = true;
-		err = ovl_dir_read(&lowerpath, &rdd);
-		list_del(&rdd.middle);
-	}
-out:
 	return err;
 }
 
 static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
 {
-	struct ovl_cache_entry *p;
+	struct list_head *p;
 	loff_t off = 0;
 
-	list_for_each_entry(p, &od->cache->entries, l_node) {
-		if (p->is_cursor)
-			continue;
+	list_for_each(p, &od->cache->entries) {
 		if (off >= pos)
 			break;
 		off++;
 	}
-	list_move_tail(&od->cursor.l_node, &p->l_node);
+	/* Cursor is safe since the cache is stable */
+	od->cursor = p;
 }
 
 static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
@@ -367,6 +343,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
 {
 	struct ovl_dir_file *od = file->private_data;
 	struct dentry *dentry = file->f_path.dentry;
+	struct ovl_cache_entry *p;
 
 	if (!ctx->pos)
 		ovl_dir_reset(file);
@@ -385,19 +362,13 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
 		ovl_seek_cursor(od, ctx->pos);
 	}
 
-	while (od->cursor.l_node.next != &od->cache->entries) {
-		struct ovl_cache_entry *p;
-
-		p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node);
-		/* Skip cursors */
-		if (!p->is_cursor) {
-			if (!p->is_whiteout) {
-				if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
-					break;
-			}
-			ctx->pos++;
-		}
-		list_move(&od->cursor.l_node, &p->l_node);
+	while (od->cursor != &od->cache->entries) {
+		p = list_entry(od->cursor, struct ovl_cache_entry, l_node);
+		if (!p->is_whiteout)
+			if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
+				break;
+		od->cursor = p->l_node.next;
+		ctx->pos++;
 	}
 	return 0;
 }
@@ -452,7 +423,7 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
 	/*
 	 * Need to check if we started out being a lower dir, but got copied up
 	 */
-	if (!od->is_upper && ovl_path_type(dentry) != OVL_PATH_LOWER) {
+	if (!od->is_upper && OVL_TYPE_UPPER(ovl_path_type(dentry))) {
 		struct inode *inode = file_inode(file);
 
 		realfile = lockless_dereference(od->upperfile);
@@ -516,11 +487,9 @@ static int ovl_dir_open(struct inode *inode, struct file *file)
 		kfree(od);
 		return PTR_ERR(realfile);
 	}
-	INIT_LIST_HEAD(&od->cursor.l_node);
 	od->realfile = realfile;
-	od->is_real = (type != OVL_PATH_MERGE);
-	od->is_upper = (type != OVL_PATH_LOWER);
-	od->cursor.is_cursor = true;
+	od->is_real = !OVL_TYPE_MERGE(type);
+	od->is_upper = OVL_TYPE_UPPER(type);
 	file->private_data = od;
 
 	return 0;

fs/overlayfs/super.c

@@ -35,7 +35,8 @@ struct ovl_config {
 /* private information held for overlayfs's superblock */
 struct ovl_fs {
 	struct vfsmount *upper_mnt;
-	struct vfsmount *lower_mnt;
+	unsigned numlower;
+	struct vfsmount **lower_mnt;
 	struct dentry *workdir;
 	long lower_namelen;
 	/* pathnames of lower and upper dirs, for show_options */
@@ -47,7 +48,6 @@ struct ovl_dir_cache;
 /* private information held for every overlayfs dentry */
 struct ovl_entry {
 	struct dentry *__upperdentry;
-	struct dentry *lowerdentry;
 	struct ovl_dir_cache *cache;
 	union {
 		struct {
@@ -56,30 +56,36 @@ struct ovl_entry {
 		};
 		struct rcu_head rcu;
 	};
+	unsigned numlower;
+	struct path lowerstack[];
 };
 
-const char *ovl_opaque_xattr = "trusted.overlay.opaque";
+#define OVL_MAX_STACK 500
 
+static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
+{
+	return oe->numlower ? oe->lowerstack[0].dentry : NULL;
+}
 
 enum ovl_path_type ovl_path_type(struct dentry *dentry)
 {
 	struct ovl_entry *oe = dentry->d_fsdata;
+	enum ovl_path_type type = 0;
 
 	if (oe->__upperdentry) {
-		if (oe->lowerdentry) {
+		type = __OVL_PATH_UPPER;
+
+		if (oe->numlower) {
 			if (S_ISDIR(dentry->d_inode->i_mode))
-				return OVL_PATH_MERGE;
-			else
-				return OVL_PATH_UPPER;
-		} else {
-			if (oe->opaque)
-				return OVL_PATH_UPPER;
-			else
-				return OVL_PATH_PURE_UPPER;
+				type |= __OVL_PATH_MERGE;
+		} else if (!oe->opaque) {
+			type |= __OVL_PATH_PURE;
 		}
 	} else {
-		return OVL_PATH_LOWER;
+		if (oe->numlower > 1)
+			type |= __OVL_PATH_MERGE;
 	}
+	return type;
 }
 
 static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
@@ -98,10 +104,9 @@ void ovl_path_upper(struct dentry *dentry, struct path *path)
 
 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
 {
-
 	enum ovl_path_type type = ovl_path_type(dentry);
 
-	if (type == OVL_PATH_LOWER)
+	if (!OVL_TYPE_UPPER(type))
 		ovl_path_lower(dentry, path);
 	else
 		ovl_path_upper(dentry, path);
@@ -120,7 +125,7 @@ struct dentry *ovl_dentry_lower(struct dentry *dentry)
 {
 	struct ovl_entry *oe = dentry->d_fsdata;
 
-	return oe->lowerdentry;
+	return __ovl_dentry_lower(oe);
 }
 
 struct dentry *ovl_dentry_real(struct dentry *dentry)
@@ -130,7 +135,7 @@ struct dentry *ovl_dentry_real(struct dentry *dentry)
 
 	realdentry = ovl_upperdentry_dereference(oe);
 	if (!realdentry)
-		realdentry = oe->lowerdentry;
+		realdentry = __ovl_dentry_lower(oe);
 
 	return realdentry;
 }
@@ -143,7 +148,7 @@ struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
 	if (realdentry) {
 		*is_upper = true;
 	} else {
-		realdentry = oe->lowerdentry;
+		realdentry = __ovl_dentry_lower(oe);
 		*is_upper = false;
 	}
 	return realdentry;
@@ -165,11 +170,9 @@ void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
 
 void ovl_path_lower(struct dentry *dentry, struct path *path)
 {
-	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 	struct ovl_entry *oe = dentry->d_fsdata;
 
-	path->mnt = ofs->lower_mnt;
-	path->dentry = oe->lowerdentry;
+	*path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
 }
 
 int ovl_want_write(struct dentry *dentry)
@@ -249,7 +252,7 @@ static bool ovl_is_opaquedir(struct dentry *dentry)
 	if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr)
 		return false;
 
-	res = inode->i_op->getxattr(dentry, ovl_opaque_xattr, &val, 1);
+	res = inode->i_op->getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
 	if (res == 1 && val == 'y')
 		return true;
 
@@ -261,8 +264,11 @@ static void ovl_dentry_release(struct dentry *dentry)
 	struct ovl_entry *oe = dentry->d_fsdata;
 
 	if (oe) {
+		unsigned int i;
+
 		dput(oe->__upperdentry);
-		dput(oe->lowerdentry);
+		for (i = 0; i < oe->numlower; i++)
+			dput(oe->lowerstack[i].dentry);
 		kfree_rcu(oe, rcu);
 	}
 }
@@ -271,9 +277,15 @@ static const struct dentry_operations ovl_dentry_operations = {
 	.d_release = ovl_dentry_release,
 };
 
-static struct ovl_entry *ovl_alloc_entry(void)
+static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
-	return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
+	size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
+	struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
+
+	if (oe)
+		oe->numlower = numlower;
+
+	return oe;
 }
 
 static inline struct dentry *ovl_lookup_real(struct dentry *dir,
@@ -295,82 +307,154 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir,
 	return dentry;
 }
 
+/*
+ * Returns next layer in stack starting from top.
+ * Returns -1 if this is the last layer.
+ */
+int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
+{
+	struct ovl_entry *oe = dentry->d_fsdata;
+
+	BUG_ON(idx < 0);
+	if (idx == 0) {
+		ovl_path_upper(dentry, path);
+		if (path->dentry)
+			return oe->numlower ? 1 : -1;
+		idx++;
+	}
+	BUG_ON(idx > oe->numlower);
+	*path = oe->lowerstack[idx - 1];
+
+	return (idx < oe->numlower) ? idx + 1 : -1;
+}
+
 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			  unsigned int flags)
 {
 	struct ovl_entry *oe;
-	struct dentry *upperdir;
-	struct dentry *lowerdir;
-	struct dentry *upperdentry = NULL;
-	struct dentry *lowerdentry = NULL;
+	struct ovl_entry *poe = dentry->d_parent->d_fsdata;
+	struct path *stack = NULL;
+	struct dentry *upperdir, *upperdentry = NULL;
+	unsigned int ctr = 0;
 	struct inode *inode = NULL;
+	bool upperopaque = false;
+	struct dentry *this, *prev = NULL;
+	unsigned int i;
 	int err;
 
-	err = -ENOMEM;
-	oe = ovl_alloc_entry();
-	if (!oe)
-		goto out;
-
-	upperdir = ovl_dentry_upper(dentry->d_parent);
-	lowerdir = ovl_dentry_lower(dentry->d_parent);
-
+	upperdir = ovl_upperdentry_dereference(poe);
 	if (upperdir) {
-		upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
-		err = PTR_ERR(upperdentry);
-		if (IS_ERR(upperdentry))
-			goto out_put_dir;
-
-		if (lowerdir && upperdentry) {
-			if (ovl_is_whiteout(upperdentry)) {
-				dput(upperdentry);
-				upperdentry = NULL;
-				oe->opaque = true;
-			} else if (ovl_is_opaquedir(upperdentry)) {
-				oe->opaque = true;
+		this = ovl_lookup_real(upperdir, &dentry->d_name);
+		err = PTR_ERR(this);
+		if (IS_ERR(this))
+			goto out;
+
+		if (this) {
+			if (ovl_is_whiteout(this)) {
+				dput(this);
+				this = NULL;
+				upperopaque = true;
+			} else if (poe->numlower && ovl_is_opaquedir(this)) {
+				upperopaque = true;
 			}
 		}
+		upperdentry = prev = this;
 	}
-	if (lowerdir && !oe->opaque) {
-		lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
-		err = PTR_ERR(lowerdentry);
-		if (IS_ERR(lowerdentry))
-			goto out_dput_upper;
+
+	if (!upperopaque && poe->numlower) {
+		err = -ENOMEM;
+		stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
+		if (!stack)
+			goto out_put_upper;
 	}
 
-	if (lowerdentry && upperdentry &&
-	    (!S_ISDIR(upperdentry->d_inode->i_mode) ||
-	     !S_ISDIR(lowerdentry->d_inode->i_mode))) {
-		dput(lowerdentry);
-		lowerdentry = NULL;
-		oe->opaque = true;
+	for (i = 0; !upperopaque && i < poe->numlower; i++) {
+		bool opaque = false;
+		struct path lowerpath = poe->lowerstack[i];
+
+		this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
+		err = PTR_ERR(this);
+		if (IS_ERR(this)) {
+			/*
+			 * If it's positive, then treat ENAMETOOLONG as ENOENT.
+			 */
+			if (err == -ENAMETOOLONG && (upperdentry || ctr))
+				continue;
+			goto out_put;
+		}
+		if (!this)
+			continue;
+		if (ovl_is_whiteout(this)) {
+			dput(this);
+			break;
+		}
+		/*
+		 * Only makes sense to check opaque dir if this is not the
+		 * lowermost layer.
+		 */
+		if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
+			opaque = true;
+
+		if (prev && (!S_ISDIR(prev->d_inode->i_mode) ||
+			     !S_ISDIR(this->d_inode->i_mode))) {
+			/*
+			 * FIXME: check for upper-opaqueness maybe better done
+			 * in remove code.
+			 */
+			if (prev == upperdentry)
+				upperopaque = true;
+			dput(this);
+			break;
+		}
+		/*
+		 * If this is a non-directory then stop here.
+		 */
+		if (!S_ISDIR(this->d_inode->i_mode))
+			opaque = true;
+
+		stack[ctr].dentry = this;
+		stack[ctr].mnt = lowerpath.mnt;
+		ctr++;
+		prev = this;
+		if (opaque)
+			break;
 	}
 
-	if (lowerdentry || upperdentry) {
+	oe = ovl_alloc_entry(ctr);
+	err = -ENOMEM;
+	if (!oe)
+		goto out_put;
+
+	if (upperdentry || ctr) {
 		struct dentry *realdentry;
 
-		realdentry = upperdentry ? upperdentry : lowerdentry;
+		realdentry = upperdentry ? upperdentry : stack[0].dentry;
+
 		err = -ENOMEM;
 		inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
 				      oe);
 		if (!inode)
-			goto out_dput;
+			goto out_free_oe;
 		ovl_copyattr(realdentry->d_inode, inode);
 	}
 
+	oe->opaque = upperopaque;
 	oe->__upperdentry = upperdentry;
-	oe->lowerdentry = lowerdentry;
-
+	memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
+	kfree(stack);
 	dentry->d_fsdata = oe;
 	d_add(dentry, inode);
 
 	return NULL;
 
-out_dput:
-	dput(lowerdentry);
-out_dput_upper:
-	dput(upperdentry);
-out_put_dir:
+out_free_oe:
 	kfree(oe);
+out_put:
+	for (i = 0; i < ctr; i++)
+		dput(stack[i].dentry);
+	kfree(stack);
+out_put_upper:
+	dput(upperdentry);
 out:
 	return ERR_PTR(err);
 }
@@ -383,10 +467,12 @@ struct file *ovl_path_open(struct path *path, int flags)
 static void ovl_put_super(struct super_block *sb)
 {
 	struct ovl_fs *ufs = sb->s_fs_info;
+	unsigned i;
 
 	dput(ufs->workdir);
 	mntput(ufs->upper_mnt);
-	mntput(ufs->lower_mnt);
+	for (i = 0; i < ufs->numlower; i++)
+		mntput(ufs->lower_mnt[i]);
 
 	kfree(ufs->config.lowerdir);
 	kfree(ufs->config.upperdir);
@@ -400,7 +486,7 @@ static void ovl_put_super(struct super_block *sb)
  * @buf: The struct kstatfs to fill in with stats
  *
  * Get the filesystem statistics.  As writes always target the upper layer
- * filesystem pass the statfs to the same filesystem.
+ * filesystem pass the statfs to the upper filesystem (if it exists)
  */
 static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
@@ -409,7 +495,7 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
 	struct path path;
 	int err;
 
-	ovl_path_upper(root_dentry, &path);
+	ovl_path_real(root_dentry, &path);
 
 	err = vfs_statfs(&path, buf);
 	if (!err) {
@@ -432,8 +518,21 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
 	struct ovl_fs *ufs = sb->s_fs_info;
 
 	seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
-	seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
-	seq_printf(m, ",workdir=%s", ufs->config.workdir);
+	if (ufs->config.upperdir) {
+		seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
+		seq_printf(m, ",workdir=%s", ufs->config.workdir);
+	}
+	return 0;
+}
+
+static int ovl_remount(struct super_block *sb, int *flags, char *data)
+{
+	struct ovl_fs *ufs = sb->s_fs_info;
+
+	if (!(*flags & MS_RDONLY) &&
+	    (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)))
+		return -EROFS;
+
 	return 0;
 }
 
@@ -441,6 +540,7 @@ static const struct super_operations ovl_super_operations = {
 	.put_super	= ovl_put_super,
 	.statfs		= ovl_statfs,
 	.show_options	= ovl_show_options,
+	.remount_fs	= ovl_remount,
 };
 
 enum {
@@ -585,24 +685,6 @@ static void ovl_unescape(char *s)
 	}
 }
 
-static int ovl_mount_dir(const char *name, struct path *path)
-{
-	int err;
-	char *tmp = kstrdup(name, GFP_KERNEL);
-
-	if (!tmp)
-		return -ENOMEM;
-
-	ovl_unescape(tmp);
-	err = kern_path(tmp, LOOKUP_FOLLOW, path);
-	if (err) {
-		pr_err("overlayfs: failed to resolve '%s': %i\n", tmp, err);
-		err = -EINVAL;
-	}
-	kfree(tmp);
-	return err;
-}
-
 static bool ovl_is_allowed_fs_type(struct dentry *root)
 {
 	const struct dentry_operations *dop = root->d_op;
@@ -622,6 +704,75 @@ static bool ovl_is_allowed_fs_type(struct dentry *root)
 	return true;
 }
 
+static int ovl_mount_dir_noesc(const char *name, struct path *path)
+{
+	int err = -EINVAL;
+
+	if (!*name) {
+		pr_err("overlayfs: empty lowerdir\n");
+		goto out;
+	}
+	err = kern_path(name, LOOKUP_FOLLOW, path);
+	if (err) {
+		pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
+		goto out;
+	}
+	err = -EINVAL;
+	if (!ovl_is_allowed_fs_type(path->dentry)) {
+		pr_err("overlayfs: filesystem on '%s' not supported\n", name);
+		goto out_put;
+	}
+	if (!S_ISDIR(path->dentry->d_inode->i_mode)) {
+		pr_err("overlayfs: '%s' not a directory\n", name);
+		goto out_put;
+	}
+	return 0;
+
+out_put:
+	path_put(path);
+out:
+	return err;
+}
+
+static int ovl_mount_dir(const char *name, struct path *path)
+{
+	int err = -ENOMEM;
+	char *tmp = kstrdup(name, GFP_KERNEL);
+
+	if (tmp) {
+		ovl_unescape(tmp);
+		err = ovl_mount_dir_noesc(tmp, path);
+		kfree(tmp);
+	}
+	return err;
+}
+
+static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
+			 int *stack_depth)
+{
+	int err;
+	struct kstatfs statfs;
+
+	err = ovl_mount_dir_noesc(name, path);
+	if (err)
+		goto out;
+
+	err = vfs_statfs(path, &statfs);
+	if (err) {
+		pr_err("overlayfs: statfs failed on '%s'\n", name);
+		goto out_put;
+	}
+	*namelen = max(*namelen, statfs.f_namelen);
+	*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
+
+	return 0;
+
+out_put:
+	path_put(path);
+out:
+	return err;
+}
+
 /* Workdir should not be subdir of upperdir and vice versa */
 static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
 {
@@ -634,16 +785,39 @@ static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
 	return ok;
 }
 
+static unsigned int ovl_split_lowerdirs(char *str)
+{
+	unsigned int ctr = 1;
+	char *s, *d;
+
+	for (s = d = str;; s++, d++) {
+		if (*s == '\\') {
+			s++;
+		} else if (*s == ':') {
+			*d = '\0';
+			ctr++;
+			continue;
+		}
+		*d = *s;
+		if (!*s)
+			break;
+	}
+	return ctr;
+}
+
 static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 {
-	struct path lowerpath;
-	struct path upperpath;
-	struct path workpath;
-	struct inode *root_inode;
+	struct path upperpath = { NULL, NULL };
+	struct path workpath = { NULL, NULL };
 	struct dentry *root_dentry;
 	struct ovl_entry *oe;
 	struct ovl_fs *ufs;
-	struct kstatfs statfs;
+	struct path *stack = NULL;
+	char *lowertmp;
+	char *lower;
+	unsigned int numlower;
+	unsigned int stacklen = 0;
+	unsigned int i;
 	int err;
 
 	err = -ENOMEM;
@@ -655,123 +829,135 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	if (err)
 		goto out_free_config;
 
-	/* FIXME: workdir is not needed for a R/O mount */
 	err = -EINVAL;
-	if (!ufs->config.upperdir || !ufs->config.lowerdir ||
-	    !ufs->config.workdir) {
-		pr_err("overlayfs: missing upperdir or lowerdir or workdir\n");
+	if (!ufs->config.lowerdir) {
+		pr_err("overlayfs: missing 'lowerdir'\n");
 		goto out_free_config;
 	}
 
-	err = -ENOMEM;
-	oe = ovl_alloc_entry();
-	if (oe == NULL)
-		goto out_free_config;
-
-	err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
-	if (err)
-		goto out_free_oe;
-
-	err = ovl_mount_dir(ufs->config.lowerdir, &lowerpath);
-	if (err)
-		goto out_put_upperpath;
+	sb->s_stack_depth = 0;
+	if (ufs->config.upperdir) {
+		/* FIXME: workdir is not needed for a R/O mount */
+		if (!ufs->config.workdir) {
+			pr_err("overlayfs: missing 'workdir'\n");
+			goto out_free_config;
+		}
 
-	err = ovl_mount_dir(ufs->config.workdir, &workpath);
-	if (err)
-		goto out_put_lowerpath;
+		err = ovl_mount_dir(ufs->config.upperdir, &upperpath);
+		if (err)
+			goto out_free_config;
 
-	err = -EINVAL;
-	if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
-	    !S_ISDIR(lowerpath.dentry->d_inode->i_mode) ||
-	    !S_ISDIR(workpath.dentry->d_inode->i_mode)) {
-		pr_err("overlayfs: upperdir or lowerdir or workdir not a directory\n");
-		goto out_put_workpath;
-	}
+		err = ovl_mount_dir(ufs->config.workdir, &workpath);
+		if (err)
+			goto out_put_upperpath;
 
-	if (upperpath.mnt != workpath.mnt) {
-		pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
-		goto out_put_workpath;
-	}
-	if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
-		pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
-		goto out_put_workpath;
+		err = -EINVAL;
+		if (upperpath.mnt != workpath.mnt) {
+			pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
+			goto out_put_workpath;
+		}
+		if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
+			pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
+			goto out_put_workpath;
+		}
+		sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
 	}
-
-	if (!ovl_is_allowed_fs_type(upperpath.dentry)) {
-		pr_err("overlayfs: filesystem of upperdir is not supported\n");
+	err = -ENOMEM;
+	lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL);
+	if (!lowertmp)
 		goto out_put_workpath;
-	}
 
-	if (!ovl_is_allowed_fs_type(lowerpath.dentry)) {
-		pr_err("overlayfs: filesystem of lowerdir is not supported\n");
-		goto out_put_workpath;
-	}
+	err = -EINVAL;
+	stacklen = ovl_split_lowerdirs(lowertmp);
+	if (stacklen > OVL_MAX_STACK)
+		goto out_free_lowertmp;
+
+	stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
+	if (!stack)
+		goto out_free_lowertmp;
+
+	lower = lowertmp;
+	for (numlower = 0; numlower < stacklen; numlower++) {
+		err = ovl_lower_dir(lower, &stack[numlower],
+				    &ufs->lower_namelen, &sb->s_stack_depth);
+		if (err)
+			goto out_put_lowerpath;
 
-	err = vfs_statfs(&lowerpath, &statfs);
-	if (err) {
-		pr_err("overlayfs: statfs failed on lowerpath\n");
-		goto out_put_workpath;
+		lower = strchr(lower, '\0') + 1;
 	}
-	ufs->lower_namelen = statfs.f_namelen;
-
-	sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
-				lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
 
 	err = -EINVAL;
+	sb->s_stack_depth++;
 	if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
 		pr_err("overlayfs: maximum fs stacking depth exceeded\n");
-		goto out_put_workpath;
+		goto out_put_lowerpath;
 	}
 
-	ufs->upper_mnt = clone_private_mount(&upperpath);
-	err = PTR_ERR(ufs->upper_mnt);
-	if (IS_ERR(ufs->upper_mnt)) {
-		pr_err("overlayfs: failed to clone upperpath\n");
-		goto out_put_workpath;
-	}
+	if (ufs->config.upperdir) {
+		ufs->upper_mnt = clone_private_mount(&upperpath);
+		err = PTR_ERR(ufs->upper_mnt);
+		if (IS_ERR(ufs->upper_mnt)) {
+			pr_err("overlayfs: failed to clone upperpath\n");
+			goto out_put_lowerpath;
+		}
 
-	ufs->lower_mnt = clone_private_mount(&lowerpath);
-	err = PTR_ERR(ufs->lower_mnt);
-	if (IS_ERR(ufs->lower_mnt)) {
-		pr_err("overlayfs: failed to clone lowerpath\n");
-		goto out_put_upper_mnt;
+		ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
+		err = PTR_ERR(ufs->workdir);
+		if (IS_ERR(ufs->workdir)) {
+			pr_err("overlayfs: failed to create directory %s/%s\n",
+			       ufs->config.workdir, OVL_WORKDIR_NAME);
+			goto out_put_upper_mnt;
+		}
 	}
 
-	ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
-	err = PTR_ERR(ufs->workdir);
-	if (IS_ERR(ufs->workdir)) {
-		pr_err("overlayfs: failed to create directory %s/%s\n",
-		       ufs->config.workdir, OVL_WORKDIR_NAME);
-		goto out_put_lower_mnt;
-	}
+	err = -ENOMEM;
+	ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);
+	if (ufs->lower_mnt == NULL)
+		goto out_put_workdir;
+	for (i = 0; i < numlower; i++) {
+		struct vfsmount *mnt = clone_private_mount(&stack[i]);
 
-	/*
-	 * Make lower_mnt R/O.  That way fchmod/fchown on lower file
-	 * will fail instead of modifying lower fs.
-	 */
-	ufs->lower_mnt->mnt_flags |= MNT_READONLY;
+		err = PTR_ERR(mnt);
+		if (IS_ERR(mnt)) {
+			pr_err("overlayfs: failed to clone lowerpath\n");
+			goto out_put_lower_mnt;
+		}
+		/*
+		 * Make lower_mnt R/O.  That way fchmod/fchown on lower file
+		 * will fail instead of modifying lower fs.
+		 */
+		mnt->mnt_flags |= MNT_READONLY;
+
+		ufs->lower_mnt[ufs->numlower] = mnt;
+		ufs->numlower++;
+	}
 
-	/* If the upper fs is r/o, we mark overlayfs r/o too */
-	if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
+	/* If the upper fs is r/o or nonexistent, we mark overlayfs r/o too */
+	if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))
 		sb->s_flags |= MS_RDONLY;
 
 	sb->s_d_op = &ovl_dentry_operations;
 
 	err = -ENOMEM;
-	root_inode = ovl_new_inode(sb, S_IFDIR, oe);
-	if (!root_inode)
-		goto out_put_workdir;
+	oe = ovl_alloc_entry(numlower);
+	if (!oe)
+		goto out_put_lower_mnt;
 
-	root_dentry = d_make_root(root_inode);
+	root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, oe));
 	if (!root_dentry)
-		goto out_put_workdir;
+		goto out_free_oe;
 
 	mntput(upperpath.mnt);
-	mntput(lowerpath.mnt);
+	for (i = 0; i < numlower; i++)
+		mntput(stack[i].mnt);
 	path_put(&workpath);
+	kfree(lowertmp);
 
 	oe->__upperdentry = upperpath.dentry;
-	oe->lowerdentry = lowerpath.dentry;
+	for (i = 0; i < numlower; i++) {
+		oe->lowerstack[i].dentry = stack[i].dentry;
+		oe->lowerstack[i].mnt = ufs->lower_mnt[i];
+	}
 
 	root_dentry->d_fsdata = oe;
 
@@ -782,20 +968,26 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 
 	return 0;
 
+out_free_oe:
+	kfree(oe);
+out_put_lower_mnt:
+	for (i = 0; i < ufs->numlower; i++)
+		mntput(ufs->lower_mnt[i]);
+	kfree(ufs->lower_mnt);
 out_put_workdir:
 	dput(ufs->workdir);
-out_put_lower_mnt:
-	mntput(ufs->lower_mnt);
 out_put_upper_mnt:
 	mntput(ufs->upper_mnt);
+out_put_lowerpath:
+	for (i = 0; i < numlower; i++)
+		path_put(&stack[i]);
+	kfree(stack);
+out_free_lowertmp:
+	kfree(lowertmp);
 out_put_workpath:
 	path_put(&workpath);
-out_put_lowerpath:
-	path_put(&lowerpath);
 out_put_upperpath:
 	path_put(&upperpath);
-out_free_oe:
-	kfree(oe);
 out_free_config:
 	kfree(ufs->config.lowerdir);
 	kfree(ufs->config.upperdir);

fs/posix_acl.c

@@ -564,13 +564,11 @@ posix_acl_create(struct inode *dir, umode_t *mode,
 
 	*acl = posix_acl_clone(p, GFP_NOFS);
 	if (!*acl)
-		return -ENOMEM;
+		goto no_mem;
 
 	ret = posix_acl_create_masq(*acl, mode);
-	if (ret < 0) {
-		posix_acl_release(*acl);
-		return -ENOMEM;
-	}
+	if (ret < 0)
+		goto no_mem_clone;
 
 	if (ret == 0) {
 		posix_acl_release(*acl);
@@ -591,6 +589,12 @@ no_acl:
 	*default_acl = NULL;
 	*acl = NULL;
 	return 0;
+
+no_mem_clone:
+	posix_acl_release(*acl);
+no_mem:
+	posix_acl_release(p);
+	return -ENOMEM;
 }
 EXPORT_SYMBOL_GPL(posix_acl_create);
 
@@ -772,7 +776,7 @@ posix_acl_xattr_get(struct dentry *dentry, const char *name,
 
 	if (!IS_POSIXACL(dentry->d_inode))
 		return -EOPNOTSUPP;
-	if (S_ISLNK(dentry->d_inode->i_mode))
+	if (d_is_symlink(dentry))
 		return -EOPNOTSUPP;
 
 	acl = get_acl(dentry->d_inode, type);
@@ -832,7 +836,7 @@ posix_acl_xattr_list(struct dentry *dentry, char *list, size_t list_size,
 
 	if (!IS_POSIXACL(dentry->d_inode))
 		return -EOPNOTSUPP;
-	if (S_ISLNK(dentry->d_inode->i_mode))
+	if (d_is_symlink(dentry))
 		return -EOPNOTSUPP;
 
 	if (type == ACL_TYPE_ACCESS)

fs/proc/generic.c

@@ -19,7 +19,6 @@
 #include <linux/mount.h>
 #include <linux/init.h>
 #include <linux/idr.h>
-#include <linux/namei.h>
 #include <linux/bitops.h>
 #include <linux/spinlock.h>
 #include <linux/completion.h>
@@ -223,17 +222,6 @@ void proc_free_inum(unsigned int inum)
 	spin_unlock_irqrestore(&proc_inum_lock, flags);
 }
 
-static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
-	nd_set_link(nd, __PDE_DATA(dentry->d_inode));
-	return NULL;
-}
-
-static const struct inode_operations proc_link_inode_operations = {
-	.readlink	= generic_readlink,
-	.follow_link	= proc_follow_link,
-};
-
 /*
  * Don't create negative dentries here, return -ENOENT by hand
  * instead.

fs/proc/inode.c

@@ -23,6 +23,7 @@
 #include <linux/slab.h>
 #include <linux/mount.h>
 #include <linux/magic.h>
+#include <linux/namei.h>
 
 #include <asm/uaccess.h>
 
@@ -393,6 +394,26 @@ static const struct file_operations proc_reg_file_ops_no_compat = {
 };
 #endif
 
+static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	struct proc_dir_entry *pde = PDE(dentry->d_inode);
+	if (unlikely(!use_pde(pde)))
+		return ERR_PTR(-EINVAL);
+	nd_set_link(nd, pde->data);
+	return pde;
+}
+
+static void proc_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
+{
+	unuse_pde(p);
+}
+
+const struct inode_operations proc_link_inode_operations = {
+	.readlink	= generic_readlink,
+	.follow_link	= proc_follow_link,
+	.put_link	= proc_put_link,
+};
+
 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
 {
 	struct inode *inode = new_inode_pseudo(sb);

fs/proc/internal.h

@@ -200,6 +200,7 @@ struct pde_opener {
 	int closing;
 	struct completion *c;
 };
+extern const struct inode_operations proc_link_inode_operations;
 
 extern const struct inode_operations proc_pid_link_inode_operations;
 

fs/reiserfs/xattr.c

@@ -266,7 +266,7 @@ static int reiserfs_for_each_xattr(struct inode *inode,
 		for (i = 0; !err && i < buf.count && buf.dentries[i]; i++) {
 			struct dentry *dentry = buf.dentries[i];
 
-			if (!S_ISDIR(dentry->d_inode->i_mode))
+			if (!d_is_dir(dentry))
 				err = action(dentry, data);
 
 			dput(dentry);
@@ -322,7 +322,7 @@ static int delete_one_xattr(struct dentry *dentry, void *data)
 	struct inode *dir = dentry->d_parent->d_inode;
 
 	/* This is the xattr dir, handle specially. */
-	if (S_ISDIR(dentry->d_inode->i_mode))
+	if (d_is_dir(dentry))
 		return xattr_rmdir(dir, dentry);
 
 	return xattr_unlink(dir, dentry);

fs/super.c

@@ -71,7 +71,7 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
 	if (!(sc->gfp_mask & __GFP_FS))
 		return SHRINK_STOP;
 
-	if (!grab_super_passive(sb))
+	if (!trylock_super(sb))
 		return SHRINK_STOP;
 
 	if (sb->s_op->nr_cached_objects)
@@ -105,7 +105,7 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
 		freed += sb->s_op->free_cached_objects(sb, sc);
 	}
 
-	drop_super(sb);
+	up_read(&sb->s_umount);
 	return freed;
 }
 
@@ -118,7 +118,7 @@ static unsigned long super_cache_count(struct shrinker *shrink,
 	sb = container_of(shrink, struct super_block, s_shrink);
 
 	/*
-	 * Don't call grab_super_passive as it is a potential
+	 * Don't call trylock_super as it is a potential
 	 * scalability bottleneck. The counts could get updated
 	 * between super_cache_count and super_cache_scan anyway.
 	 * Call to super_cache_count with shrinker_rwsem held
@@ -348,35 +348,31 @@ static int grab_super(struct super_block *s) __releases(sb_lock)
 }
 
 /*
- *	grab_super_passive - acquire a passive reference
+ *	trylock_super - try to grab ->s_umount shared
  *	@sb: reference we are trying to grab
  *
- *	Tries to acquire a passive reference. This is used in places where we
+ *	Try to prevent fs shutdown.  This is used in places where we
  *	cannot take an active reference but we need to ensure that the
- *	superblock does not go away while we are working on it. It returns
- *	false if a reference was not gained, and returns true with the s_umount
- *	lock held in read mode if a reference is gained. On successful return,
- *	the caller must drop the s_umount lock and the passive reference when
- *	done.
+ *	filesystem is not shut down while we are working on it. It returns
+ *	false if we cannot acquire s_umount or if we lose the race and
+ *	filesystem already got into shutdown, and returns true with the s_umount
+ *	lock held in read mode in case of success. On successful return,
+ *	the caller must drop the s_umount lock when done.
+ *
+ *	Note that unlike get_super() et.al. this one does *not* bump ->s_count.
+ *	The reason why it's safe is that we are OK with doing trylock instead
+ *	of down_read().  There's a couple of places that are OK with that, but
+ *	it's very much not a general-purpose interface.
  */
-bool grab_super_passive(struct super_block *sb)
+bool trylock_super(struct super_block *sb)
 {
-	spin_lock(&sb_lock);
-	if (hlist_unhashed(&sb->s_instances)) {
-		spin_unlock(&sb_lock);
-		return false;
-	}
-
-	sb->s_count++;
-	spin_unlock(&sb_lock);
-
 	if (down_read_trylock(&sb->s_umount)) {
-		if (sb->s_root && (sb->s_flags & MS_BORN))
+		if (!hlist_unhashed(&sb->s_instances) &&
+		    sb->s_root && (sb->s_flags & MS_BORN))
 			return true;
 		up_read(&sb->s_umount);
 	}
 
-	put_super(sb);
 	return false;
 }
 

fs/xfs/xfs_ioctl.c

@@ -287,7 +287,7 @@ xfs_readlink_by_handle(
 		return PTR_ERR(dentry);
 
 	/* Restrict this handle operation to symlinks only. */
-	if (!S_ISLNK(dentry->d_inode->i_mode)) {
+	if (!d_is_symlink(dentry)) {
 		error = -EINVAL;
 		goto out_dput;
 	}

include/linux/dcache.h

@@ -215,13 +215,16 @@ struct dentry_operations {
 #define DCACHE_LRU_LIST			0x00080000
 
 #define DCACHE_ENTRY_TYPE		0x00700000
-#define DCACHE_MISS_TYPE		0x00000000 /* Negative dentry */
-#define DCACHE_DIRECTORY_TYPE		0x00100000 /* Normal directory */
-#define DCACHE_AUTODIR_TYPE		0x00200000 /* Lookupless directory (presumed automount) */
-#define DCACHE_SYMLINK_TYPE		0x00300000 /* Symlink */
-#define DCACHE_FILE_TYPE		0x00400000 /* Other file type */
+#define DCACHE_MISS_TYPE		0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
+#define DCACHE_WHITEOUT_TYPE		0x00100000 /* Whiteout dentry (stop pathwalk) */
+#define DCACHE_DIRECTORY_TYPE		0x00200000 /* Normal directory */
+#define DCACHE_AUTODIR_TYPE		0x00300000 /* Lookupless directory (presumed automount) */
+#define DCACHE_REGULAR_TYPE		0x00400000 /* Regular file type (or fallthru to such) */
+#define DCACHE_SPECIAL_TYPE		0x00500000 /* Other file type (or fallthru to such) */
+#define DCACHE_SYMLINK_TYPE		0x00600000 /* Symlink (or fallthru to such) */
 
 #define DCACHE_MAY_FREE			0x00800000
+#define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
 
 extern seqlock_t rename_lock;
 
@@ -423,6 +426,16 @@ static inline unsigned __d_entry_type(const struct dentry *dentry)
 	return dentry->d_flags & DCACHE_ENTRY_TYPE;
 }
 
+static inline bool d_is_miss(const struct dentry *dentry)
+{
+	return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
+}
+
+static inline bool d_is_whiteout(const struct dentry *dentry)
+{
+	return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
+}
+
 static inline bool d_can_lookup(const struct dentry *dentry)
 {
 	return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
@@ -443,14 +456,25 @@ static inline bool d_is_symlink(const struct dentry *dentry)
 	return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
 }
 
+static inline bool d_is_reg(const struct dentry *dentry)
+{
+	return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
+}
+
+static inline bool d_is_special(const struct dentry *dentry)
+{
+	return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
+}
+
 static inline bool d_is_file(const struct dentry *dentry)
 {
-	return __d_entry_type(dentry) == DCACHE_FILE_TYPE;
+	return d_is_reg(dentry) || d_is_special(dentry);
 }
 
 static inline bool d_is_negative(const struct dentry *dentry)
 {
-	return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
+	// TODO: check d_is_whiteout(dentry) also.
+	return d_is_miss(dentry);
 }
 
 static inline bool d_is_positive(const struct dentry *dentry)
@@ -458,10 +482,75 @@ static inline bool d_is_positive(const struct dentry *dentry)
 	return !d_is_negative(dentry);
 }
 
+extern void d_set_fallthru(struct dentry *dentry);
+
+static inline bool d_is_fallthru(const struct dentry *dentry)
+{
+	return dentry->d_flags & DCACHE_FALLTHRU;
+}
+
+
 extern int sysctl_vfs_cache_pressure;
 
 static inline unsigned long vfs_pressure_ratio(unsigned long val)
 {
 	return mult_frac(val, sysctl_vfs_cache_pressure, 100);
 }
+
+/**
+ * d_inode - Get the actual inode of this dentry
+ * @dentry: The dentry to query
+ *
+ * This is the helper normal filesystems should use to get at their own inodes
+ * in their own dentries and ignore the layering superimposed upon them.
+ */
+static inline struct inode *d_inode(const struct dentry *dentry)
+{
+	return dentry->d_inode;
+}
+
+/**
+ * d_inode_rcu - Get the actual inode of this dentry with ACCESS_ONCE()
+ * @dentry: The dentry to query
+ *
+ * This is the helper normal filesystems should use to get at their own inodes
+ * in their own dentries and ignore the layering superimposed upon them.
+ */
+static inline struct inode *d_inode_rcu(const struct dentry *dentry)
+{
+	return ACCESS_ONCE(dentry->d_inode);
+}
+
+/**
+ * d_backing_inode - Get upper or lower inode we should be using
+ * @upper: The upper layer
+ *
+ * This is the helper that should be used to get at the inode that will be used
+ * if this dentry were to be opened as a file.  The inode may be on the upper
+ * dentry or it may be on a lower dentry pinned by the upper.
+ *
+ * Normal filesystems should not use this to access their own inodes.
+ */
+static inline struct inode *d_backing_inode(const struct dentry *upper)
+{
+	struct inode *inode = upper->d_inode;
+
+	return inode;
+}
+
+/**
+ * d_backing_dentry - Get upper or lower dentry we should be using
+ * @upper: The upper layer
+ *
+ * This is the helper that should be used to get the dentry of the inode that
+ * will be used if this dentry were opened as a file.  It may be the upper
+ * dentry or it may be a lower dentry pinned by the upper.
+ *
+ * Normal filesystems should not use this to access their own dentries.
+ */
+static inline struct dentry *d_backing_dentry(struct dentry *upper)
+{
+	return upper;
+}
+
 #endif	/* __LINUX_DCACHE_H */

mm/shmem.c

@@ -2319,8 +2319,8 @@ static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
 
 static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
 {
-	bool old_is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
-	bool new_is_dir = S_ISDIR(new_dentry->d_inode->i_mode);
+	bool old_is_dir = d_is_dir(old_dentry);
+	bool new_is_dir = d_is_dir(new_dentry);
 
 	if (old_dir != new_dir && old_is_dir != new_is_dir) {
 		if (old_is_dir) {

security/apparmor/include/apparmor.h

@@ -112,9 +112,9 @@ static inline unsigned int aa_dfa_null_transition(struct aa_dfa *dfa,
 	return aa_dfa_next(dfa, start, 0);
 }
 
-static inline bool mediated_filesystem(struct inode *inode)
+static inline bool mediated_filesystem(struct dentry *dentry)
 {
-	return !(inode->i_sb->s_flags & MS_NOUSER);
+	return !(dentry->d_sb->s_flags & MS_NOUSER);
 }
 
 #endif /* __APPARMOR_H */

security/apparmor/lsm.c

@@ -226,7 +226,7 @@ static int common_perm_rm(int op, struct path *dir,
 	struct inode *inode = dentry->d_inode;
 	struct path_cond cond = { };
 
-	if (!inode || !dir->mnt || !mediated_filesystem(inode))
+	if (!inode || !dir->mnt || !mediated_filesystem(dentry))
 		return 0;
 
 	cond.uid = inode->i_uid;
@@ -250,7 +250,7 @@ static int common_perm_create(int op, struct path *dir, struct dentry *dentry,
 {
 	struct path_cond cond = { current_fsuid(), mode };
 
-	if (!dir->mnt || !mediated_filesystem(dir->dentry->d_inode))
+	if (!dir->mnt || !mediated_filesystem(dir->dentry))
 		return 0;
 
 	return common_perm_dir_dentry(op, dir, dentry, mask, &cond);
@@ -285,7 +285,7 @@ static int apparmor_path_truncate(struct path *path)
 				  path->dentry->d_inode->i_mode
 	};
 
-	if (!path->mnt || !mediated_filesystem(path->dentry->d_inode))
+	if (!path->mnt || !mediated_filesystem(path->dentry))
 		return 0;
 
 	return common_perm(OP_TRUNC, path, MAY_WRITE | AA_MAY_META_WRITE,
@@ -305,7 +305,7 @@ static int apparmor_path_link(struct dentry *old_dentry, struct path *new_dir,
 	struct aa_profile *profile;
 	int error = 0;
 
-	if (!mediated_filesystem(old_dentry->d_inode))
+	if (!mediated_filesystem(old_dentry))
 		return 0;
 
 	profile = aa_current_profile();
@@ -320,7 +320,7 @@ static int apparmor_path_rename(struct path *old_dir, struct dentry *old_dentry,
 	struct aa_profile *profile;
 	int error = 0;
 
-	if (!mediated_filesystem(old_dentry->d_inode))
+	if (!mediated_filesystem(old_dentry))
 		return 0;
 
 	profile = aa_current_profile();
@@ -346,7 +346,7 @@ static int apparmor_path_rename(struct path *old_dir, struct dentry *old_dentry,
 
 static int apparmor_path_chmod(struct path *path, umode_t mode)
 {
-	if (!mediated_filesystem(path->dentry->d_inode))
+	if (!mediated_filesystem(path->dentry))
 		return 0;
 
 	return common_perm_mnt_dentry(OP_CHMOD, path->mnt, path->dentry, AA_MAY_CHMOD);
@@ -358,7 +358,7 @@ static int apparmor_path_chown(struct path *path, kuid_t uid, kgid_t gid)
 				   path->dentry->d_inode->i_mode
 	};
 
-	if (!mediated_filesystem(path->dentry->d_inode))
+	if (!mediated_filesystem(path->dentry))
 		return 0;
 
 	return common_perm(OP_CHOWN, path, AA_MAY_CHOWN, &cond);
@@ -366,7 +366,7 @@ static int apparmor_path_chown(struct path *path, kuid_t uid, kgid_t gid)
 
 static int apparmor_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
 {
-	if (!mediated_filesystem(dentry->d_inode))
+	if (!mediated_filesystem(dentry))
 		return 0;
 
 	return common_perm_mnt_dentry(OP_GETATTR, mnt, dentry,
@@ -379,7 +379,7 @@ static int apparmor_file_open(struct file *file, const struct cred *cred)
 	struct aa_profile *profile;
 	int error = 0;
 
-	if (!mediated_filesystem(file_inode(file)))
+	if (!mediated_filesystem(file->f_path.dentry))
 		return 0;
 
 	/* If in exec, permission is handled by bprm hooks.
@@ -432,7 +432,7 @@ static int common_file_perm(int op, struct file *file, u32 mask)
 	BUG_ON(!fprofile);
 
 	if (!file->f_path.mnt ||
-	    !mediated_filesystem(file_inode(file)))
+	    !mediated_filesystem(file->f_path.dentry))
 		return 0;
 
 	profile = __aa_current_profile();

security/apparmor/path.c

@@ -114,7 +114,7 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
 	 *    security_path hooks as a deleted dentry except without an inode
 	 *    allocated.
 	 */
-	if (d_unlinked(path->dentry) && path->dentry->d_inode &&
+	if (d_unlinked(path->dentry) && d_is_positive(path->dentry) &&
 	    !(flags & PATH_MEDIATE_DELETED)) {
 			error = -ENOENT;
 			goto out;

security/inode.c

@@ -203,7 +203,7 @@ void securityfs_remove(struct dentry *dentry)
 	mutex_lock(&parent->d_inode->i_mutex);
 	if (positive(dentry)) {
 		if (dentry->d_inode) {
-			if (S_ISDIR(dentry->d_inode->i_mode))
+			if (d_is_dir(dentry))
 				simple_rmdir(parent->d_inode, dentry);
 			else
 				simple_unlink(parent->d_inode, dentry);

security/selinux/hooks.c

@@ -1799,7 +1799,7 @@ static inline int may_rename(struct inode *old_dir,
 
 	old_dsec = old_dir->i_security;
 	old_isec = old_dentry->d_inode->i_security;
-	old_is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
+	old_is_dir = d_is_dir(old_dentry);
 	new_dsec = new_dir->i_security;
 
 	ad.type = LSM_AUDIT_DATA_DENTRY;
@@ -1822,14 +1822,14 @@ static inline int may_rename(struct inode *old_dir,
 
 	ad.u.dentry = new_dentry;
 	av = DIR__ADD_NAME | DIR__SEARCH;
-	if (new_dentry->d_inode)
+	if (d_is_positive(new_dentry))
 		av |= DIR__REMOVE_NAME;
 	rc = avc_has_perm(sid, new_dsec->sid, SECCLASS_DIR, av, &ad);
 	if (rc)
 		return rc;
-	if (new_dentry->d_inode) {
+	if (d_is_positive(new_dentry)) {
 		new_isec = new_dentry->d_inode->i_security;
-		new_is_dir = S_ISDIR(new_dentry->d_inode->i_mode);
+		new_is_dir = d_is_dir(new_dentry);
 		rc = avc_has_perm(sid, new_isec->sid,
 				  new_isec->sclass,
 				  (new_is_dir ? DIR__RMDIR : FILE__UNLINK), &ad);

security/smack/smack_lsm.c

@@ -855,7 +855,7 @@ static int smack_inode_link(struct dentry *old_dentry, struct inode *dir,
 	rc = smk_curacc(isp, MAY_WRITE, &ad);
 	rc = smk_bu_inode(old_dentry->d_inode, MAY_WRITE, rc);
 
-	if (rc == 0 && new_dentry->d_inode != NULL) {
+	if (rc == 0 && d_is_positive(new_dentry)) {
 		isp = smk_of_inode(new_dentry->d_inode);
 		smk_ad_setfield_u_fs_path_dentry(&ad, new_dentry);
 		rc = smk_curacc(isp, MAY_WRITE, &ad);
@@ -961,7 +961,7 @@ static int smack_inode_rename(struct inode *old_inode,
 	rc = smk_curacc(isp, MAY_READWRITE, &ad);
 	rc = smk_bu_inode(old_dentry->d_inode, MAY_READWRITE, rc);
 
-	if (rc == 0 && new_dentry->d_inode != NULL) {
+	if (rc == 0 && d_is_positive(new_dentry)) {
 		isp = smk_of_inode(new_dentry->d_inode);
 		smk_ad_setfield_u_fs_path_dentry(&ad, new_dentry);
 		rc = smk_curacc(isp, MAY_READWRITE, &ad);

security/tomoyo/file.c

@@ -905,11 +905,9 @@ int tomoyo_path2_perm(const u8 operation, struct path *path1,
 	    !tomoyo_get_realpath(&buf2, path2))
 		goto out;
 	switch (operation) {
-		struct dentry *dentry;
 	case TOMOYO_TYPE_RENAME:
 	case TOMOYO_TYPE_LINK:
-		dentry = path1->dentry;
-		if (!dentry->d_inode || !S_ISDIR(dentry->d_inode->i_mode))
+		if (!d_is_dir(path1->dentry))
 			break;
 		/* fall through */
 	case TOMOYO_TYPE_PIVOT_ROOT: