Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1235 insertions, 0 deletions

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
new file mode 100644
index 000000000..2b2106400
--- /dev/null
+++ b/fs/overlayfs/readdir.c
@@ -0,0 +1,1235 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/namei.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include <linux/rbtree.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include <linux/ratelimit.h>
+#include "overlayfs.h"
+
+struct ovl_cache_entry {
+	unsigned int len;
+	unsigned int type;
+	u64 real_ino;
+	u64 ino;
+	struct list_head l_node;
+	struct rb_node node;
+	struct ovl_cache_entry *next_maybe_whiteout;
+	bool is_upper;
+	bool is_whiteout;
+	char name[];
+};
+
+struct ovl_dir_cache {
+	long refcount;
+	u64 version;
+	struct list_head entries;
+	struct rb_root root;
+};
+
+struct ovl_readdir_data {
+	struct dir_context ctx;
+	struct dentry *dentry;
+	bool is_lowest;
+	struct rb_root *root;
+	struct list_head *list;
+	struct list_head middle;
+	struct ovl_cache_entry *first_maybe_whiteout;
+	int count;
+	int err;
+	bool is_upper;
+	bool d_type_supported;
+};
+
+struct ovl_dir_file {
+	bool is_real;
+	bool is_upper;
+	struct ovl_dir_cache *cache;
+	struct list_head *cursor;
+	struct file *realfile;
+	struct file *upperfile;
+};
+
+static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
+{
+	return rb_entry(n, struct ovl_cache_entry, node);
+}
+
+static bool ovl_cache_entry_find_link(const char *name, int len,
+				      struct rb_node ***link,
+				      struct rb_node **parent)
+{
+	bool found = false;
+	struct rb_node **newp = *link;
+
+	while (!found && *newp) {
+		int cmp;
+		struct ovl_cache_entry *tmp;
+
+		*parent = *newp;
+		tmp = ovl_cache_entry_from_node(*newp);
+		cmp = strncmp(name, tmp->name, len);
+		if (cmp > 0)
+			newp = &tmp->node.rb_right;
+		else if (cmp < 0 || len < tmp->len)
+			newp = &tmp->node.rb_left;
+		else
+			found = true;
+	}
+	*link = newp;
+
+	return found;
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
+						    const char *name, int len)
+{
+	struct rb_node *node = root->rb_node;
+	int cmp;
+
+	while (node) {
+		struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
+
+		cmp = strncmp(name, p->name, len);
+		if (cmp > 0)
+			node = p->node.rb_right;
+		else if (cmp < 0 || len < p->len)
+			node = p->node.rb_left;
+		else
+			return p;
+	}
+
+	return NULL;
+}
+
+static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
+			   struct ovl_cache_entry *p)
+{
+	/* Don't care if not doing ovl_iter() */
+	if (!rdd->dentry)
+		return false;
+
+	/* Always recalc d_ino when remapping lower inode numbers */
+	if (ovl_xino_bits(rdd->dentry->d_sb))
+		return true;
+
+	/* Always recalc d_ino for parent */
+	if (strcmp(p->name, "..") == 0)
+		return true;
+
+	/* If this is lower, then native d_ino will do */
+	if (!rdd->is_upper)
+		return false;
+
+	/*
+	 * Recalc d_ino for '.' and for all entries if dir is impure (contains
+	 * copied up entries)
+	 */
+	if ((p->name[0] == '.' && p->len == 1) ||
+	    ovl_test_flag(OVL_IMPURE, d_inode(rdd->dentry)))
+		return true;
+
+	return false;
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
+						   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)
+		return NULL;
+
+	memcpy(p->name, name, len);
+	p->name[len] = '\0';
+	p->len = len;
+	p->type = d_type;
+	p->real_ino = ino;
+	p->ino = ino;
+	/* Defer setting d_ino for upper entry to ovl_iterate() */
+	if (ovl_calc_d_ino(rdd, p))
+		p->ino = 0;
+	p->is_upper = rdd->is_upper;
+	p->is_whiteout = false;
+
+	if (d_type == DT_CHR) {
+		p->next_maybe_whiteout = rdd->first_maybe_whiteout;
+		rdd->first_maybe_whiteout = p;
+	}
+	return p;
+}
+
+static bool ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
+				  const char *name, int len, u64 ino,
+				  unsigned int d_type)
+{
+	struct rb_node **newp = &rdd->root->rb_node;
+	struct rb_node *parent = NULL;
+	struct ovl_cache_entry *p;
+
+	if (ovl_cache_entry_find_link(name, len, &newp, &parent))
+		return true;
+
+	p = ovl_cache_entry_new(rdd, name, len, ino, d_type);
+	if (p == NULL) {
+		rdd->err = -ENOMEM;
+		return false;
+	}
+
+	list_add_tail(&p->l_node, rdd->list);
+	rb_link_node(&p->node, parent, newp);
+	rb_insert_color(&p->node, rdd->root);
+
+	return true;
+}
+
+static bool ovl_fill_lowest(struct ovl_readdir_data *rdd,
+			   const char *name, int namelen,
+			   loff_t offset, u64 ino, unsigned int d_type)
+{
+	struct ovl_cache_entry *p;
+
+	p = ovl_cache_entry_find(rdd->root, name, namelen);
+	if (p) {
+		list_move_tail(&p->l_node, &rdd->middle);
+	} else {
+		p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
+		if (p == NULL)
+			rdd->err = -ENOMEM;
+		else
+			list_add_tail(&p->l_node, &rdd->middle);
+	}
+
+	return rdd->err == 0;
+}
+
+void ovl_cache_free(struct list_head *list)
+{
+	struct ovl_cache_entry *p;
+	struct ovl_cache_entry *n;
+
+	list_for_each_entry_safe(p, n, list, l_node)
+		kfree(p);
+
+	INIT_LIST_HEAD(list);
+}
+
+void ovl_dir_cache_free(struct inode *inode)
+{
+	struct ovl_dir_cache *cache = ovl_dir_cache(inode);
+
+	if (cache) {
+		ovl_cache_free(&cache->entries);
+		kfree(cache);
+	}
+}
+
+static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry)
+{
+	struct ovl_dir_cache *cache = od->cache;
+
+	WARN_ON(cache->refcount <= 0);
+	cache->refcount--;
+	if (!cache->refcount) {
+		if (ovl_dir_cache(d_inode(dentry)) == cache)
+			ovl_set_dir_cache(d_inode(dentry), NULL);
+
+		ovl_cache_free(&cache->entries);
+		kfree(cache);
+	}
+}
+
+static bool ovl_fill_merge(struct dir_context *ctx, const char *name,
+			  int namelen, loff_t offset, u64 ino,
+			  unsigned int d_type)
+{
+	struct ovl_readdir_data *rdd =
+		container_of(ctx, struct ovl_readdir_data, ctx);
+
+	rdd->count++;
+	if (!rdd->is_lowest)
+		return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
+	else
+		return ovl_fill_lowest(rdd, name, namelen, offset, ino, d_type);
+}
+
+static int ovl_check_whiteouts(const struct path *path, struct ovl_readdir_data *rdd)
+{
+	int err;
+	struct ovl_cache_entry *p;
+	struct dentry *dentry, *dir = path->dentry;
+	const struct cred *old_cred;
+
+	old_cred = ovl_override_creds(rdd->dentry->d_sb);
+
+	err = down_write_killable(&dir->d_inode->i_rwsem);
+	if (!err) {
+		while (rdd->first_maybe_whiteout) {
+			p = rdd->first_maybe_whiteout;
+			rdd->first_maybe_whiteout = p->next_maybe_whiteout;
+			dentry = lookup_one(mnt_user_ns(path->mnt), p->name, dir, p->len);
+			if (!IS_ERR(dentry)) {
+				p->is_whiteout = ovl_is_whiteout(dentry);
+				dput(dentry);
+			}
+		}
+		inode_unlock(dir->d_inode);
+	}
+	revert_creds(old_cred);
+
+	return err;
+}
+
+static inline int ovl_dir_read(const struct path *realpath,
+			       struct ovl_readdir_data *rdd)
+{
+	struct file *realfile;
+	int err;
+
+	realfile = ovl_path_open(realpath, O_RDONLY | O_LARGEFILE);
+	if (IS_ERR(realfile))
+		return PTR_ERR(realfile);
+
+	rdd->first_maybe_whiteout = NULL;
+	rdd->ctx.pos = 0;
+	do {
+		rdd->count = 0;
+		rdd->err = 0;
+		err = iterate_dir(realfile, &rdd->ctx);
+		if (err >= 0)
+			err = rdd->err;
+	} while (!err && rdd->count);
+
+	if (!err && rdd->first_maybe_whiteout && rdd->dentry)
+		err = ovl_check_whiteouts(realpath, rdd);
+
+	fput(realfile);
+
+	return err;
+}
+
+static void ovl_dir_reset(struct file *file)
+{
+	struct ovl_dir_file *od = file->private_data;
+	struct ovl_dir_cache *cache = od->cache;
+	struct dentry *dentry = file->f_path.dentry;
+	bool is_real;
+
+	if (cache && ovl_dentry_version_get(dentry) != cache->version) {
+		ovl_cache_put(od, dentry);
+		od->cache = NULL;
+		od->cursor = NULL;
+	}
+	is_real = ovl_dir_is_real(dentry);
+	if (od->is_real != is_real) {
+		/* is_real can only become false when dir is copied up */
+		if (WARN_ON(is_real))
+			return;
+		od->is_real = false;
+	}
+}
+
+static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list,
+	struct rb_root *root)
+{
+	int err;
+	struct path realpath;
+	struct ovl_readdir_data rdd = {
+		.ctx.actor = ovl_fill_merge,
+		.dentry = dentry,
+		.list = list,
+		.root = root,
+		.is_lowest = false,
+	};
+	int idx, next;
+
+	for (idx = 0; idx != -1; idx = next) {
+		next = ovl_path_next(idx, dentry, &realpath);
+		rdd.is_upper = ovl_dentry_upper(dentry) == realpath.dentry;
+
+		if (next != -1) {
+			err = ovl_dir_read(&realpath, &rdd);
+			if (err)
+				break;
+		} else {
+			/*
+			 * Insert lowest layer entries before upper ones, this
+			 * allows offsets to be reasonably constant
+			 */
+			list_add(&rdd.middle, rdd.list);
+			rdd.is_lowest = true;
+			err = ovl_dir_read(&realpath, &rdd);
+			list_del(&rdd.middle);
+		}
+	}
+	return err;
+}
+
+static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
+{
+	struct list_head *p;
+	loff_t off = 0;
+
+	list_for_each(p, &od->cache->entries) {
+		if (off >= pos)
+			break;
+		off++;
+	}
+	/* Cursor is safe since the cache is stable */
+	od->cursor = p;
+}
+
+static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
+{
+	int res;
+	struct ovl_dir_cache *cache;
+
+	cache = ovl_dir_cache(d_inode(dentry));
+	if (cache && ovl_dentry_version_get(dentry) == cache->version) {
+		WARN_ON(!cache->refcount);
+		cache->refcount++;
+		return cache;
+	}
+	ovl_set_dir_cache(d_inode(dentry), NULL);
+
+	cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
+	if (!cache)
+		return ERR_PTR(-ENOMEM);
+
+	cache->refcount = 1;
+	INIT_LIST_HEAD(&cache->entries);
+	cache->root = RB_ROOT;
+
+	res = ovl_dir_read_merged(dentry, &cache->entries, &cache->root);
+	if (res) {
+		ovl_cache_free(&cache->entries);
+		kfree(cache);
+		return ERR_PTR(res);
+	}
+
+	cache->version = ovl_dentry_version_get(dentry);
+	ovl_set_dir_cache(d_inode(dentry), cache);
+
+	return cache;
+}
+
+/* Map inode number to lower fs unique range */
+static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
+			       const char *name, int namelen, bool warn)
+{
+	unsigned int xinoshift = 64 - xinobits;
+
+	if (unlikely(ino >> xinoshift)) {
+		if (warn) {
+			pr_warn_ratelimited("d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
+					    namelen, name, ino, xinobits);
+		}
+		return ino;
+	}
+
+	/*
+	 * The lowest xinobit is reserved for mapping the non-peresistent inode
+	 * numbers range, but this range is only exposed via st_ino, not here.
+	 */
+	return ino | ((u64)fsid) << (xinoshift + 1);
+}
+
+/*
+ * Set d_ino for upper entries. Non-upper entries should always report
+ * the uppermost real inode ino and should not call this function.
+ *
+ * When not all layer are on same fs, report real ino also for upper.
+ *
+ * When all layers are on the same fs, and upper has a reference to
+ * copy up origin, call vfs_getattr() on the overlay entry to make
+ * sure that d_ino will be consistent with st_ino from stat(2).
+ */
+static int ovl_cache_update_ino(const struct path *path, struct ovl_cache_entry *p)
+
+{
+	struct dentry *dir = path->dentry;
+	struct dentry *this = NULL;
+	enum ovl_path_type type;
+	u64 ino = p->real_ino;
+	int xinobits = ovl_xino_bits(dir->d_sb);
+	int err = 0;
+
+	if (!ovl_same_dev(dir->d_sb))
+		goto out;
+
+	if (p->name[0] == '.') {
+		if (p->len == 1) {
+			this = dget(dir);
+			goto get;
+		}
+		if (p->len == 2 && p->name[1] == '.') {
+			/* we shall not be moved */
+			this = dget(dir->d_parent);
+			goto get;
+		}
+	}
+	this = lookup_one(mnt_user_ns(path->mnt), p->name, dir, p->len);
+	if (IS_ERR_OR_NULL(this) || !this->d_inode) {
+		/* Mark a stale entry */
+		p->is_whiteout = true;
+		if (IS_ERR(this)) {
+			err = PTR_ERR(this);
+			this = NULL;
+			goto fail;
+		}
+		goto out;
+	}
+
+get:
+	type = ovl_path_type(this);
+	if (OVL_TYPE_ORIGIN(type)) {
+		struct kstat stat;
+		struct path statpath = *path;
+
+		statpath.dentry = this;
+		err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
+		if (err)
+			goto fail;
+
+		/*
+		 * Directory inode is always on overlay st_dev.
+		 * Non-dir with ovl_same_dev() could be on pseudo st_dev in case
+		 * of xino bits overflow.
+		 */
+		WARN_ON_ONCE(S_ISDIR(stat.mode) &&
+			     dir->d_sb->s_dev != stat.dev);
+		ino = stat.ino;
+	} else if (xinobits && !OVL_TYPE_UPPER(type)) {
+		ino = ovl_remap_lower_ino(ino, xinobits,
+					  ovl_layer_lower(this)->fsid,
+					  p->name, p->len,
+					  ovl_xino_warn(dir->d_sb));
+	}
+
+out:
+	p->ino = ino;
+	dput(this);
+	return err;
+
+fail:
+	pr_warn_ratelimited("failed to look up (%s) for ino (%i)\n",
+			    p->name, err);
+	goto out;
+}
+
+static bool ovl_fill_plain(struct dir_context *ctx, const char *name,
+			  int namelen, loff_t offset, u64 ino,
+			  unsigned int d_type)
+{
+	struct ovl_cache_entry *p;
+	struct ovl_readdir_data *rdd =
+		container_of(ctx, struct ovl_readdir_data, ctx);
+
+	rdd->count++;
+	p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
+	if (p == NULL) {
+		rdd->err = -ENOMEM;
+		return false;
+	}
+	list_add_tail(&p->l_node, rdd->list);
+
+	return true;
+}
+
+static int ovl_dir_read_impure(const struct path *path,  struct list_head *list,
+			       struct rb_root *root)
+{
+	int err;
+	struct path realpath;
+	struct ovl_cache_entry *p, *n;
+	struct ovl_readdir_data rdd = {
+		.ctx.actor = ovl_fill_plain,
+		.list = list,
+		.root = root,
+	};
+
+	INIT_LIST_HEAD(list);
+	*root = RB_ROOT;
+	ovl_path_upper(path->dentry, &realpath);
+
+	err = ovl_dir_read(&realpath, &rdd);
+	if (err)
+		return err;
+
+	list_for_each_entry_safe(p, n, list, l_node) {
+		if (strcmp(p->name, ".") != 0 &&
+		    strcmp(p->name, "..") != 0) {
+			err = ovl_cache_update_ino(path, p);
+			if (err)
+				return err;
+		}
+		if (p->ino == p->real_ino) {
+			list_del(&p->l_node);
+			kfree(p);
+		} else {
+			struct rb_node **newp = &root->rb_node;
+			struct rb_node *parent = NULL;
+
+			if (WARN_ON(ovl_cache_entry_find_link(p->name, p->len,
+							      &newp, &parent)))
+				return -EIO;
+
+			rb_link_node(&p->node, parent, newp);
+			rb_insert_color(&p->node, root);
+		}
+	}
+	return 0;
+}
+
+static struct ovl_dir_cache *ovl_cache_get_impure(const struct path *path)
+{
+	int res;
+	struct dentry *dentry = path->dentry;
+	struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
+	struct ovl_dir_cache *cache;
+
+	cache = ovl_dir_cache(d_inode(dentry));
+	if (cache && ovl_dentry_version_get(dentry) == cache->version)
+		return cache;
+
+	/* Impure cache is not refcounted, free it here */
+	ovl_dir_cache_free(d_inode(dentry));
+	ovl_set_dir_cache(d_inode(dentry), NULL);
+
+	cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
+	if (!cache)
+		return ERR_PTR(-ENOMEM);
+
+	res = ovl_dir_read_impure(path, &cache->entries, &cache->root);
+	if (res) {
+		ovl_cache_free(&cache->entries);
+		kfree(cache);
+		return ERR_PTR(res);
+	}
+	if (list_empty(&cache->entries)) {
+		/*
+		 * A good opportunity to get rid of an unneeded "impure" flag.
+		 * Removing the "impure" xattr is best effort.
+		 */
+		if (!ovl_want_write(dentry)) {
+			ovl_removexattr(ofs, ovl_dentry_upper(dentry),
+					OVL_XATTR_IMPURE);
+			ovl_drop_write(dentry);
+		}
+		ovl_clear_flag(OVL_IMPURE, d_inode(dentry));
+		kfree(cache);
+		return NULL;
+	}
+
+	cache->version = ovl_dentry_version_get(dentry);
+	ovl_set_dir_cache(d_inode(dentry), cache);
+
+	return cache;
+}
+
+struct ovl_readdir_translate {
+	struct dir_context *orig_ctx;
+	struct ovl_dir_cache *cache;
+	struct dir_context ctx;
+	u64 parent_ino;
+	int fsid;
+	int xinobits;
+	bool xinowarn;
+};
+
+static bool ovl_fill_real(struct dir_context *ctx, const char *name,
+			   int namelen, loff_t offset, u64 ino,
+			   unsigned int d_type)
+{
+	struct ovl_readdir_translate *rdt =
+		container_of(ctx, struct ovl_readdir_translate, ctx);
+	struct dir_context *orig_ctx = rdt->orig_ctx;
+
+	if (rdt->parent_ino && strcmp(name, "..") == 0) {
+		ino = rdt->parent_ino;
+	} else if (rdt->cache) {
+		struct ovl_cache_entry *p;
+
+		p = ovl_cache_entry_find(&rdt->cache->root, name, namelen);
+		if (p)
+			ino = p->ino;
+	} else if (rdt->xinobits) {
+		ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,
+					  name, namelen, rdt->xinowarn);
+	}
+
+	return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
+}
+
+static bool ovl_is_impure_dir(struct file *file)
+{
+	struct ovl_dir_file *od = file->private_data;
+	struct inode *dir = d_inode(file->f_path.dentry);
+
+	/*
+	 * Only upper dir can be impure, but if we are in the middle of
+	 * iterating a lower real dir, dir could be copied up and marked
+	 * impure. We only want the impure cache if we started iterating
+	 * a real upper dir to begin with.
+	 */
+	return od->is_upper && ovl_test_flag(OVL_IMPURE, dir);
+
+}
+
+static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
+{
+	int err;
+	struct ovl_dir_file *od = file->private_data;
+	struct dentry *dir = file->f_path.dentry;
+	const struct ovl_layer *lower_layer = ovl_layer_lower(dir);
+	struct ovl_readdir_translate rdt = {
+		.ctx.actor = ovl_fill_real,
+		.orig_ctx = ctx,
+		.xinobits = ovl_xino_bits(dir->d_sb),
+		.xinowarn = ovl_xino_warn(dir->d_sb),
+	};
+
+	if (rdt.xinobits && lower_layer)
+		rdt.fsid = lower_layer->fsid;
+
+	if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
+		struct kstat stat;
+		struct path statpath = file->f_path;
+
+		statpath.dentry = dir->d_parent;
+		err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
+		if (err)
+			return err;
+
+		WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
+		rdt.parent_ino = stat.ino;
+	}
+
+	if (ovl_is_impure_dir(file)) {
+		rdt.cache = ovl_cache_get_impure(&file->f_path);
+		if (IS_ERR(rdt.cache))
+			return PTR_ERR(rdt.cache);
+	}
+
+	err = iterate_dir(od->realfile, &rdt.ctx);
+	ctx->pos = rdt.ctx.pos;
+
+	return err;
+}
+
+
+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;
+	const struct cred *old_cred;
+	int err;
+
+	old_cred = ovl_override_creds(dentry->d_sb);
+	if (!ctx->pos)
+		ovl_dir_reset(file);
+
+	if (od->is_real) {
+		/*
+		 * If parent is merge, then need to adjust d_ino for '..', if
+		 * dir is impure then need to adjust d_ino for copied up
+		 * entries.
+		 */
+		if (ovl_xino_bits(dentry->d_sb) ||
+		    (ovl_same_fs(dentry->d_sb) &&
+		     (ovl_is_impure_dir(file) ||
+		      OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
+			err = ovl_iterate_real(file, ctx);
+		} else {
+			err = iterate_dir(od->realfile, ctx);
+		}
+		goto out;
+	}
+
+	if (!od->cache) {
+		struct ovl_dir_cache *cache;
+
+		cache = ovl_cache_get(dentry);
+		err = PTR_ERR(cache);
+		if (IS_ERR(cache))
+			goto out;
+
+		od->cache = cache;
+		ovl_seek_cursor(od, ctx->pos);
+	}
+
+	while (od->cursor != &od->cache->entries) {
+		p = list_entry(od->cursor, struct ovl_cache_entry, l_node);
+		if (!p->is_whiteout) {
+			if (!p->ino) {
+				err = ovl_cache_update_ino(&file->f_path, p);
+				if (err)
+					goto out;
+			}
+		}
+		/* ovl_cache_update_ino() sets is_whiteout on stale entry */
+		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++;
+	}
+	err = 0;
+out:
+	revert_creds(old_cred);
+	return err;
+}
+
+static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
+{
+	loff_t res;
+	struct ovl_dir_file *od = file->private_data;
+
+	inode_lock(file_inode(file));
+	if (!file->f_pos)
+		ovl_dir_reset(file);
+
+	if (od->is_real) {
+		res = vfs_llseek(od->realfile, offset, origin);
+		file->f_pos = od->realfile->f_pos;
+	} else {
+		res = -EINVAL;
+
+		switch (origin) {
+		case SEEK_CUR:
+			offset += file->f_pos;
+			break;
+		case SEEK_SET:
+			break;
+		default:
+			goto out_unlock;
+		}
+		if (offset < 0)
+			goto out_unlock;
+
+		if (offset != file->f_pos) {
+			file->f_pos = offset;
+			if (od->cache)
+				ovl_seek_cursor(od, offset);
+		}
+		res = offset;
+	}
+out_unlock:
+	inode_unlock(file_inode(file));
+
+	return res;
+}
+
+static struct file *ovl_dir_open_realfile(const struct file *file,
+					  const struct path *realpath)
+{
+	struct file *res;
+	const struct cred *old_cred;
+
+	old_cred = ovl_override_creds(file_inode(file)->i_sb);
+	res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));
+	revert_creds(old_cred);
+
+	return res;
+}
+
+/*
+ * Like ovl_real_fdget(), returns upperfile if dir was copied up since open.
+ * Unlike ovl_real_fdget(), this caches upperfile in file->private_data.
+ *
+ * TODO: use same abstract type for file->private_data of dir and file so
+ * upperfile could also be cached for files as well.
+ */
+struct file *ovl_dir_real_file(const struct file *file, bool want_upper)
+{
+
+	struct ovl_dir_file *od = file->private_data;
+	struct dentry *dentry = file->f_path.dentry;
+	struct file *old, *realfile = od->realfile;
+
+	if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
+		return want_upper ? NULL : realfile;
+
+	/*
+	 * Need to check if we started out being a lower dir, but got copied up
+	 */
+	if (!od->is_upper) {
+		realfile = READ_ONCE(od->upperfile);
+		if (!realfile) {
+			struct path upperpath;
+
+			ovl_path_upper(dentry, &upperpath);
+			realfile = ovl_dir_open_realfile(file, &upperpath);
+			if (IS_ERR(realfile))
+				return realfile;
+
+			old = cmpxchg_release(&od->upperfile, NULL, realfile);
+			if (old) {
+				fput(realfile);
+				realfile = old;
+			}
+		}
+	}
+
+	return realfile;
+}
+
+static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
+			 int datasync)
+{
+	struct file *realfile;
+	int err;
+
+	err = ovl_sync_status(OVL_FS(file->f_path.dentry->d_sb));
+	if (err <= 0)
+		return err;
+
+	realfile = ovl_dir_real_file(file, true);
+	err = PTR_ERR_OR_ZERO(realfile);
+
+	/* Nothing to sync for lower */
+	if (!realfile || err)
+		return err;
+
+	return vfs_fsync_range(realfile, start, end, datasync);
+}
+
+static int ovl_dir_release(struct inode *inode, struct file *file)
+{
+	struct ovl_dir_file *od = file->private_data;
+
+	if (od->cache) {
+		inode_lock(inode);
+		ovl_cache_put(od, file->f_path.dentry);
+		inode_unlock(inode);
+	}
+	fput(od->realfile);
+	if (od->upperfile)
+		fput(od->upperfile);
+	kfree(od);
+
+	return 0;
+}
+
+static int ovl_dir_open(struct inode *inode, struct file *file)
+{
+	struct path realpath;
+	struct file *realfile;
+	struct ovl_dir_file *od;
+	enum ovl_path_type type;
+
+	od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
+	if (!od)
+		return -ENOMEM;
+
+	type = ovl_path_real(file->f_path.dentry, &realpath);
+	realfile = ovl_dir_open_realfile(file, &realpath);
+	if (IS_ERR(realfile)) {
+		kfree(od);
+		return PTR_ERR(realfile);
+	}
+	od->realfile = realfile;
+	od->is_real = ovl_dir_is_real(file->f_path.dentry);
+	od->is_upper = OVL_TYPE_UPPER(type);
+	file->private_data = od;
+
+	return 0;
+}
+
+const struct file_operations ovl_dir_operations = {
+	.read		= generic_read_dir,
+	.open		= ovl_dir_open,
+	.iterate	= ovl_iterate,
+	.llseek		= ovl_dir_llseek,
+	.fsync		= ovl_dir_fsync,
+	.release	= ovl_dir_release,
+};
+
+int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
+{
+	int err;
+	struct ovl_cache_entry *p, *n;
+	struct rb_root root = RB_ROOT;
+	const struct cred *old_cred;
+
+	old_cred = ovl_override_creds(dentry->d_sb);
+	err = ovl_dir_read_merged(dentry, list, &root);
+	revert_creds(old_cred);
+	if (err)
+		return err;
+
+	err = 0;
+
+	list_for_each_entry_safe(p, n, list, l_node) {
+		/*
+		 * Select whiteouts in upperdir, they should
+		 * be cleared when deleting this directory.
+		 */
+		if (p->is_whiteout) {
+			if (p->is_upper)
+				continue;
+			goto del_entry;
+		}
+
+		if (p->name[0] == '.') {
+			if (p->len == 1)
+				goto del_entry;
+			if (p->len == 2 && p->name[1] == '.')
+				goto del_entry;
+		}
+		err = -ENOTEMPTY;
+		break;
+
+del_entry:
+		list_del(&p->l_node);
+		kfree(p);
+	}
+
+	return err;
+}
+
+void ovl_cleanup_whiteouts(struct ovl_fs *ofs, struct dentry *upper,
+			   struct list_head *list)
+{
+	struct ovl_cache_entry *p;
+
+	inode_lock_nested(upper->d_inode, I_MUTEX_CHILD);
+	list_for_each_entry(p, list, l_node) {
+		struct dentry *dentry;
+
+		if (WARN_ON(!p->is_whiteout || !p->is_upper))
+			continue;
+
+		dentry = ovl_lookup_upper(ofs, p->name, upper, p->len);
+		if (IS_ERR(dentry)) {
+			pr_err("lookup '%s/%.*s' failed (%i)\n",
+			       upper->d_name.name, p->len, p->name,
+			       (int) PTR_ERR(dentry));
+			continue;
+		}
+		if (dentry->d_inode)
+			ovl_cleanup(ofs, upper->d_inode, dentry);
+		dput(dentry);
+	}
+	inode_unlock(upper->d_inode);
+}
+
+static bool ovl_check_d_type(struct dir_context *ctx, const char *name,
+			  int namelen, loff_t offset, u64 ino,
+			  unsigned int d_type)
+{
+	struct ovl_readdir_data *rdd =
+		container_of(ctx, struct ovl_readdir_data, ctx);
+
+	/* Even if d_type is not supported, DT_DIR is returned for . and .. */
+	if (!strncmp(name, ".", namelen) || !strncmp(name, "..", namelen))
+		return true;
+
+	if (d_type != DT_UNKNOWN)
+		rdd->d_type_supported = true;
+
+	return true;
+}
+
+/*
+ * Returns 1 if d_type is supported, 0 not supported/unknown. Negative values
+ * if error is encountered.
+ */
+int ovl_check_d_type_supported(const struct path *realpath)
+{
+	int err;
+	struct ovl_readdir_data rdd = {
+		.ctx.actor = ovl_check_d_type,
+		.d_type_supported = false,
+	};
+
+	err = ovl_dir_read(realpath, &rdd);
+	if (err)
+		return err;
+
+	return rdd.d_type_supported;
+}
+
+#define OVL_INCOMPATDIR_NAME "incompat"
+
+static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, const struct path *path,
+				       int level)
+{
+	int err;
+	struct inode *dir = path->dentry->d_inode;
+	LIST_HEAD(list);
+	struct rb_root root = RB_ROOT;
+	struct ovl_cache_entry *p;
+	struct ovl_readdir_data rdd = {
+		.ctx.actor = ovl_fill_merge,
+		.dentry = NULL,
+		.list = &list,
+		.root = &root,
+		.is_lowest = false,
+	};
+	bool incompat = false;
+
+	/*
+	 * The "work/incompat" directory is treated specially - if it is not
+	 * empty, instead of printing a generic error and mounting read-only,
+	 * we will error about incompat features and fail the mount.
+	 *
+	 * When called from ovl_indexdir_cleanup(), path->dentry->d_name.name
+	 * starts with '#'.
+	 */
+	if (level == 2 &&
+	    !strcmp(path->dentry->d_name.name, OVL_INCOMPATDIR_NAME))
+		incompat = true;
+
+	err = ovl_dir_read(path, &rdd);
+	if (err)
+		goto out;
+
+	inode_lock_nested(dir, I_MUTEX_PARENT);
+	list_for_each_entry(p, &list, l_node) {
+		struct dentry *dentry;
+
+		if (p->name[0] == '.') {
+			if (p->len == 1)
+				continue;
+			if (p->len == 2 && p->name[1] == '.')
+				continue;
+		} else if (incompat) {
+			pr_err("overlay with incompat feature '%s' cannot be mounted\n",
+				p->name);
+			err = -EINVAL;
+			break;
+		}
+		dentry = ovl_lookup_upper(ofs, p->name, path->dentry, p->len);
+		if (IS_ERR(dentry))
+			continue;
+		if (dentry->d_inode)
+			err = ovl_workdir_cleanup(ofs, dir, path->mnt, dentry, level);
+		dput(dentry);
+		if (err)
+			break;
+	}
+	inode_unlock(dir);
+out:
+	ovl_cache_free(&list);
+	return err;
+}
+
+int ovl_workdir_cleanup(struct ovl_fs *ofs, struct inode *dir,
+			struct vfsmount *mnt, struct dentry *dentry, int level)
+{
+	int err;
+
+	if (!d_is_dir(dentry) || level > 1) {
+		return ovl_cleanup(ofs, dir, dentry);
+	}
+
+	err = ovl_do_rmdir(ofs, dir, dentry);
+	if (err) {
+		struct path path = { .mnt = mnt, .dentry = dentry };
+
+		inode_unlock(dir);
+		err = ovl_workdir_cleanup_recurse(ofs, &path, level + 1);
+		inode_lock_nested(dir, I_MUTEX_PARENT);
+		if (!err)
+			err = ovl_cleanup(ofs, dir, dentry);
+	}
+
+	return err;
+}
+
+int ovl_indexdir_cleanup(struct ovl_fs *ofs)
+{
+	int err;
+	struct dentry *indexdir = ofs->indexdir;
+	struct dentry *index = NULL;
+	struct inode *dir = indexdir->d_inode;
+	struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = indexdir };
+	LIST_HEAD(list);
+	struct rb_root root = RB_ROOT;
+	struct ovl_cache_entry *p;
+	struct ovl_readdir_data rdd = {
+		.ctx.actor = ovl_fill_merge,
+		.dentry = NULL,
+		.list = &list,
+		.root = &root,
+		.is_lowest = false,
+	};
+
+	err = ovl_dir_read(&path, &rdd);
+	if (err)
+		goto out;
+
+	inode_lock_nested(dir, I_MUTEX_PARENT);
+	list_for_each_entry(p, &list, l_node) {
+		if (p->name[0] == '.') {
+			if (p->len == 1)
+				continue;
+			if (p->len == 2 && p->name[1] == '.')
+				continue;
+		}
+		index = ovl_lookup_upper(ofs, p->name, indexdir, p->len);
+		if (IS_ERR(index)) {
+			err = PTR_ERR(index);
+			index = NULL;
+			break;
+		}
+		/* Cleanup leftover from index create/cleanup attempt */
+		if (index->d_name.name[0] == '#') {
+			err = ovl_workdir_cleanup(ofs, dir, path.mnt, index, 1);
+			if (err)
+				break;
+			goto next;
+		}
+		err = ovl_verify_index(ofs, index);
+		if (!err) {
+			goto next;
+		} else if (err == -ESTALE) {
+			/* Cleanup stale index entries */
+			err = ovl_cleanup(ofs, dir, index);
+		} else if (err != -ENOENT) {
+			/*
+			 * Abort mount to avoid corrupting the index if
+			 * an incompatible index entry was found or on out
+			 * of memory.
+			 */
+			break;
+		} else if (ofs->config.nfs_export) {
+			/*
+			 * Whiteout orphan index to block future open by
+			 * handle after overlay nlink dropped to zero.
+			 */
+			err = ovl_cleanup_and_whiteout(ofs, dir, index);
+		} else {
+			/* Cleanup orphan index entries */
+			err = ovl_cleanup(ofs, dir, index);
+		}
+
+		if (err)
+			break;
+
+next:
+		dput(index);
+		index = NULL;
+	}
+	dput(index);
+	inode_unlock(dir);
+out:
+	ovl_cache_free(&list);
+	if (err)
+		pr_err("failed index dir cleanup (%i)\n", err);
+	return err;
+}