[deliverable/linux.git] / fs / overlayfs / readdir.c

/*
 *
 * Copyright (C) 2011 Novell Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#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 "overlayfs.h"

struct ovl_cache_entry {
	unsigned int len;
	unsigned int type;
	u64 ino;
	struct list_head l_node;
	struct rb_node node;
	bool is_whiteout;
	bool is_cursor;
	char name[];
};

struct ovl_dir_cache {
	long refcount;
	u64 version;
	struct list_head entries;
};

struct ovl_readdir_data {
	struct dir_context ctx;
	bool is_merge;
	struct rb_root root;
	struct list_head *list;
	struct list_head middle;
	int count;
	int err;
};

struct ovl_dir_file {
	bool is_real;
	bool is_upper;
	struct ovl_dir_cache *cache;
	struct ovl_cache_entry cursor;
	struct file *realfile;
	struct file *upperfile;
};

static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
{
	return container_of(n, struct ovl_cache_entry, node);
}

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 struct ovl_cache_entry *ovl_cache_entry_new(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;
	}

	return p;
}

static int 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;

	while (*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
			return 0;
	}

	p = ovl_cache_entry_new(name, len, ino, d_type);
	if (p == NULL)
		return -ENOMEM;

	list_add_tail(&p->l_node, rdd->list);
	rb_link_node(&p->node, parent, newp);
	rb_insert_color(&p->node, &rdd->root);

	return 0;
}

static int ovl_fill_lower(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(name, namelen, ino, d_type);
		if (p == NULL)
			rdd->err = -ENOMEM;
		else
			list_add_tail(&p->l_node, &rdd->middle);
	}

	return rdd->err;
}

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);
}

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) {
		if (ovl_dir_cache(dentry) == cache)
			ovl_set_dir_cache(dentry, NULL);

		ovl_cache_free(&cache->entries);
		kfree(cache);
	}
}

static int ovl_fill_merge(void *buf, const char *name, int namelen,
			  loff_t offset, u64 ino, unsigned int d_type)
{
	struct ovl_readdir_data *rdd = buf;

	rdd->count++;
	if (!rdd->is_merge)
		return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
	else
		return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type);
}

static inline int ovl_dir_read(struct path *realpath,
			       struct ovl_readdir_data *rdd)
{
	struct file *realfile;
	int err;

	realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
	if (IS_ERR(realfile))
		return PTR_ERR(realfile);

	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);
	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;
	enum ovl_path_type type = ovl_path_type(dentry);

	if (cache && ovl_dentry_version_get(dentry) != cache->version) {
		ovl_cache_put(od, dentry);
		od->cache = NULL;
	}
	WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
	if (od->is_real && type == OVL_PATH_MERGE)
		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 ovl_readdir_data rdd = {
		.ctx.actor = ovl_fill_merge,
		.list = list,
		.root = RB_ROOT,
		.is_merge = false,
	};

	ovl_path_lower(dentry, &lowerpath);
	ovl_path_upper(dentry, &upperpath);

	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 (err)
				goto out;
		}
	}
	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;
	loff_t off = 0;

	list_for_each_entry(p, &od->cache->entries, l_node) {
		if (p->is_cursor)
			continue;
		if (off >= pos)
			break;
		off++;
	}
	list_move_tail(&od->cursor.l_node, &p->l_node);
}

static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
{
	int res;
	struct ovl_dir_cache *cache;

	cache = ovl_dir_cache(dentry);
	if (cache && ovl_dentry_version_get(dentry) == cache->version) {
		cache->refcount++;
		return cache;
	}
	ovl_set_dir_cache(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);

	res = ovl_dir_read_merged(dentry, &cache->entries);
	if (res) {
		ovl_cache_free(&cache->entries);
		kfree(cache);
		return ERR_PTR(res);
	}

	cache->version = ovl_dentry_version_get(dentry);
	ovl_set_dir_cache(dentry, cache);

	return cache;
}

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;

	if (!ctx->pos)
		ovl_dir_reset(file);

	if (od->is_real)
		return iterate_dir(od->realfile, ctx);

	if (!od->cache) {
		struct ovl_dir_cache *cache;

		cache = ovl_cache_get(dentry);
		if (IS_ERR(cache))
			return PTR_ERR(cache);

		od->cache = cache;
		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);
	}
	return 0;
}

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;

	mutex_lock(&file_inode(file)->i_mutex);
	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:
	mutex_unlock(&file_inode(file)->i_mutex);

	return res;
}

static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
			 int datasync)
{
	struct ovl_dir_file *od = file->private_data;
	struct dentry *dentry = file->f_path.dentry;
	struct file *realfile = od->realfile;

	/*
	 * 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_MERGE) {
		struct inode *inode = file_inode(file);

		realfile =lockless_dereference(od->upperfile);
		if (!realfile) {
			struct path upperpath;

			ovl_path_upper(dentry, &upperpath);
			realfile = ovl_path_open(&upperpath, O_RDONLY);
			smp_mb__before_spinlock();
			mutex_lock(&inode->i_mutex);
			if (!od->upperfile) {
				if (IS_ERR(realfile)) {
					mutex_unlock(&inode->i_mutex);
					return PTR_ERR(realfile);
				}
				od->upperfile = realfile;
			} else {
				/* somebody has beaten us to it */
				if (!IS_ERR(realfile))
					fput(realfile);
				realfile = od->upperfile;
			}
			mutex_unlock(&inode->i_mutex);
		}
	}

	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) {
		mutex_lock(&inode->i_mutex);
		ovl_cache_put(od, file->f_path.dentry);
		mutex_unlock(&inode->i_mutex);
	}
	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_path_open(&realpath, file->f_flags);
	if (IS_ERR(realfile)) {
		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;
	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;

	err = ovl_dir_read_merged(dentry, list);
	if (err)
		return err;

	err = 0;

	list_for_each_entry(p, list, l_node) {
		if (p->is_whiteout)
			continue;

		if (p->name[0] == '.') {
			if (p->len == 1)
				continue;
			if (p->len == 2 && p->name[1] == '.')
				continue;
		}
		err = -ENOTEMPTY;
		break;
	}

	return err;
}

void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
{
	struct ovl_cache_entry *p;

	mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD);
	list_for_each_entry(p, list, l_node) {
		struct dentry *dentry;

		if (!p->is_whiteout)
			continue;

		dentry = lookup_one_len(p->name, upper, p->len);
		if (IS_ERR(dentry)) {
			pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n",
			       upper->d_name.name, p->len, p->name,
			       (int) PTR_ERR(dentry));
			continue;
		}
		ovl_cleanup(upper->d_inode, dentry);
		dput(dentry);
	}
	mutex_unlock(&upper->d_inode->i_mutex);
}
Commit	Line	Data
e9be9d5e MS	1	/*
	2	*
	3	* Copyright (C) 2011 Novell Inc.
	4	*
	5	* This program is free software; you can redistribute it and/or modify it
	6	* under the terms of the GNU General Public License version 2 as published by
	7	* the Free Software Foundation.
	8	*/
	9
	10	#include <linux/fs.h>
	11	#include <linux/slab.h>
	12	#include <linux/namei.h>
	13	#include <linux/file.h>
	14	#include <linux/xattr.h>
	15	#include <linux/rbtree.h>
	16	#include <linux/security.h>
	17	#include <linux/cred.h>
	18	#include "overlayfs.h"
	19
	20	struct ovl_cache_entry {
e9be9d5e MS	21	unsigned int len;
	22	unsigned int type;
	23	u64 ino;
e9be9d5e MS	24	struct list_head l_node;
e9be9d5e MS	25	struct rb_node node;
c2096537 MS	26	bool is_whiteout;
c2096537 MS	27	bool is_cursor;
68bf8611	28	char name[];
e9be9d5e MS	29	};
	30
	31	struct ovl_dir_cache {
	32	long refcount;
	33	u64 version;
	34	struct list_head entries;
	35	};
	36
	37	struct ovl_readdir_data {
	38	struct dir_context ctx;
	39	bool is_merge;
49be4fb9	40	struct rb_root root;
e9be9d5e	41	struct list_head *list;
db6ec212	42	struct list_head middle;
e9be9d5e MS	43	int count;
	44	int err;
	45	};
	46
	47	struct ovl_dir_file {
	48	bool is_real;
	49	bool is_upper;
	50	struct ovl_dir_cache *cache;
	51	struct ovl_cache_entry cursor;
	52	struct file *realfile;
	53	struct file *upperfile;
	54	};
	55
	56	static struct ovl_cache_entry ovl_cache_entry_from_node(struct rb_node n)
	57	{
	58	return container_of(n, struct ovl_cache_entry, node);
	59	}
	60
	61	static struct ovl_cache_entry ovl_cache_entry_find(struct rb_root root,
	62	const char *name, int len)
	63	{
	64	struct rb_node *node = root->rb_node;
	65	int cmp;
	66
	67	while (node) {
	68	struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
	69
	70	cmp = strncmp(name, p->name, len);
	71	if (cmp > 0)
	72	node = p->node.rb_right;
	73	else if (cmp < 0 \|\| len < p->len)
	74	node = p->node.rb_left;
	75	else
	76	return p;
	77	}
	78
	79	return NULL;
	80	}
	81
	82	static struct ovl_cache_entry ovl_cache_entry_new(const char name, int len,
	83	u64 ino, unsigned int d_type)
	84	{
	85	struct ovl_cache_entry *p;
68bf8611	86	size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
e9be9d5e	87
68bf8611	88	p = kmalloc(size, GFP_KERNEL);
e9be9d5e	89	if (p) {
68bf8611 AV	90	memcpy(p->name, name, len);
68bf8611 AV	91	p->name[len] = '\0';
e9be9d5e MS	92	p->len = len;
	93	p->type = d_type;
	94	p->ino = ino;
	95	p->is_whiteout = false;
9f2f7d4c	96	p->is_cursor = false;
e9be9d5e MS	97	}
	98
	99	return p;
	100	}
	101
	102	static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
	103	const char *name, int len, u64 ino,
	104	unsigned int d_type)
	105	{
49be4fb9	106	struct rb_node **newp = &rdd->root.rb_node;
e9be9d5e MS	107	struct rb_node *parent = NULL;
	108	struct ovl_cache_entry *p;
	109
	110	while (*newp) {
	111	int cmp;
	112	struct ovl_cache_entry *tmp;
	113
	114	parent = *newp;
	115	tmp = ovl_cache_entry_from_node(*newp);
	116	cmp = strncmp(name, tmp->name, len);
	117	if (cmp > 0)
	118	newp = &tmp->node.rb_right;
	119	else if (cmp < 0 \|\| len < tmp->len)
	120	newp = &tmp->node.rb_left;
	121	else
	122	return 0;
	123	}
	124
	125	p = ovl_cache_entry_new(name, len, ino, d_type);
	126	if (p == NULL)
	127	return -ENOMEM;
	128
	129	list_add_tail(&p->l_node, rdd->list);
	130	rb_link_node(&p->node, parent, newp);
49be4fb9	131	rb_insert_color(&p->node, &rdd->root);
e9be9d5e MS	132
	133	return 0;
	134	}
	135
	136	static int ovl_fill_lower(struct ovl_readdir_data *rdd,
	137	const char *name, int namelen,
	138	loff_t offset, u64 ino, unsigned int d_type)
	139	{
	140	struct ovl_cache_entry *p;
	141
49be4fb9	142	p = ovl_cache_entry_find(&rdd->root, name, namelen);
e9be9d5e	143	if (p) {
db6ec212	144	list_move_tail(&p->l_node, &rdd->middle);
e9be9d5e MS	145	} else {
	146	p = ovl_cache_entry_new(name, namelen, ino, d_type);
	147	if (p == NULL)
	148	rdd->err = -ENOMEM;
	149	else
db6ec212	150	list_add_tail(&p->l_node, &rdd->middle);
e9be9d5e MS	151	}
	152
	153	return rdd->err;
	154	}
	155
	156	void ovl_cache_free(struct list_head *list)
	157	{
	158	struct ovl_cache_entry *p;
	159	struct ovl_cache_entry *n;
	160
	161	list_for_each_entry_safe(p, n, list, l_node)
	162	kfree(p);
	163
	164	INIT_LIST_HEAD(list);
	165	}
	166
	167	static void ovl_cache_put(struct ovl_dir_file od, struct dentry dentry)
	168	{
	169	struct ovl_dir_cache *cache = od->cache;
	170
3f822c62	171	list_del_init(&od->cursor.l_node);
e9be9d5e MS	172	WARN_ON(cache->refcount <= 0);
	173	cache->refcount--;
	174	if (!cache->refcount) {
	175	if (ovl_dir_cache(dentry) == cache)
	176	ovl_set_dir_cache(dentry, NULL);
	177
	178	ovl_cache_free(&cache->entries);
	179	kfree(cache);
	180	}
	181	}
	182
	183	static int ovl_fill_merge(void buf, const char name, int namelen,
	184	loff_t offset, u64 ino, unsigned int d_type)
	185	{
	186	struct ovl_readdir_data *rdd = buf;
	187
	188	rdd->count++;
	189	if (!rdd->is_merge)
	190	return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
	191	else
	192	return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type);
	193	}
	194
	195	static inline int ovl_dir_read(struct path *realpath,
	196	struct ovl_readdir_data *rdd)
	197	{
	198	struct file *realfile;
	199	int err;
	200
	201	realfile = ovl_path_open(realpath, O_RDONLY \| O_DIRECTORY);
	202	if (IS_ERR(realfile))
	203	return PTR_ERR(realfile);
	204
	205	rdd->ctx.pos = 0;
	206	do {
	207	rdd->count = 0;
	208	rdd->err = 0;
	209	err = iterate_dir(realfile, &rdd->ctx);
	210	if (err >= 0)
	211	err = rdd->err;
	212	} while (!err && rdd->count);
	213	fput(realfile);
	214
	215	return err;
	216	}
	217
	218	static void ovl_dir_reset(struct file *file)
	219	{
	220	struct ovl_dir_file *od = file->private_data;
	221	struct ovl_dir_cache *cache = od->cache;
	222	struct dentry *dentry = file->f_path.dentry;
	223	enum ovl_path_type type = ovl_path_type(dentry);
	224
	225	if (cache && ovl_dentry_version_get(dentry) != cache->version) {
	226	ovl_cache_put(od, dentry);
	227	od->cache = NULL;
	228	}
	229	WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
	230	if (od->is_real && type == OVL_PATH_MERGE)
	231	od->is_real = false;
	232	}
	233
	234	static int ovl_dir_mark_whiteouts(struct dentry *dir,
	235	struct ovl_readdir_data *rdd)
236	{
237	struct ovl_cache_entry *p;
238	struct dentry *dentry;
239	const struct cred *old_cred;
240	struct cred *override_cred;
241
242	override_cred = prepare_creds();
243	if (!override_cred) {
244	ovl_cache_free(rdd->list);
245	return -ENOMEM;
246	}
247
248	/*
249	* CAP_DAC_OVERRIDE for lookup
250	*/
251	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
252	old_cred = override_creds(override_cred);
253
254	mutex_lock(&dir->d_inode->i_mutex);
255	list_for_each_entry(p, rdd->list, l_node) {
c2096537	256	if (p->is_cursor)
e9be9d5e MS	257	continue;
	258
	259	if (p->type != DT_CHR)
	260	continue;
	261
	262	dentry = lookup_one_len(p->name, dir, p->len);
	263	if (IS_ERR(dentry))
	264	continue;
	265
	266	p->is_whiteout = ovl_is_whiteout(dentry);
	267	dput(dentry);
	268	}
	269	mutex_unlock(&dir->d_inode->i_mutex);
	270
	271	revert_creds(old_cred);
	272	put_cred(override_cred);
	273
	274	return 0;
	275	}
	276
c9f00fdb	277	static int ovl_dir_read_merged(struct dentry dentry, struct list_head list)
e9be9d5e MS	278	{
e9be9d5e MS	279	int err;
c9f00fdb MS	280	struct path lowerpath;
c9f00fdb MS	281	struct path upperpath;
e9be9d5e MS	282	struct ovl_readdir_data rdd = {
	283	.ctx.actor = ovl_fill_merge,
	284	.list = list,
49be4fb9	285	.root = RB_ROOT,
e9be9d5e MS	286	.is_merge = false,
	287	};
	288
c9f00fdb MS	289	ovl_path_lower(dentry, &lowerpath);
	290	ovl_path_upper(dentry, &upperpath);
	291
	292	if (upperpath.dentry) {
	293	err = ovl_dir_read(&upperpath, &rdd);
e9be9d5e MS	294	if (err)
	295	goto out;
	296
c9f00fdb MS	297	if (lowerpath.dentry) {
c9f00fdb MS	298	err = ovl_dir_mark_whiteouts(upperpath.dentry, &rdd);
e9be9d5e MS	299	if (err)
	300	goto out;
	301	}
	302	}
c9f00fdb	303	if (lowerpath.dentry) {
e9be9d5e MS	304	/*
	305	* Insert lowerpath entries before upperpath ones, this allows
	306	* offsets to be reasonably constant
	307	*/
db6ec212	308	list_add(&rdd.middle, rdd.list);
e9be9d5e	309	rdd.is_merge = true;
c9f00fdb	310	err = ovl_dir_read(&lowerpath, &rdd);
db6ec212	311	list_del(&rdd.middle);
e9be9d5e MS	312	}
	313	out:
	314	return err;
e9be9d5e MS	315	}
	316
	317	static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
	318	{
	319	struct ovl_cache_entry *p;
	320	loff_t off = 0;
	321
	322	list_for_each_entry(p, &od->cache->entries, l_node) {
c2096537	323	if (p->is_cursor)
e9be9d5e MS	324	continue;
	325	if (off >= pos)
	326	break;
	327	off++;
	328	}
	329	list_move_tail(&od->cursor.l_node, &p->l_node);
	330	}
	331
	332	static struct ovl_dir_cache ovl_cache_get(struct dentry dentry)
	333	{
	334	int res;
e9be9d5e MS	335	struct ovl_dir_cache *cache;
	336
	337	cache = ovl_dir_cache(dentry);
	338	if (cache && ovl_dentry_version_get(dentry) == cache->version) {
	339	cache->refcount++;
	340	return cache;
	341	}
	342	ovl_set_dir_cache(dentry, NULL);
	343
	344	cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
	345	if (!cache)
	346	return ERR_PTR(-ENOMEM);
	347
	348	cache->refcount = 1;
	349	INIT_LIST_HEAD(&cache->entries);
	350
c9f00fdb	351	res = ovl_dir_read_merged(dentry, &cache->entries);
e9be9d5e MS	352	if (res) {
	353	ovl_cache_free(&cache->entries);
	354	kfree(cache);
	355	return ERR_PTR(res);
	356	}
	357
	358	cache->version = ovl_dentry_version_get(dentry);
	359	ovl_set_dir_cache(dentry, cache);
	360
	361	return cache;
	362	}
	363
	364	static int ovl_iterate(struct file file, struct dir_context ctx)
	365	{
	366	struct ovl_dir_file *od = file->private_data;
	367	struct dentry *dentry = file->f_path.dentry;
	368
	369	if (!ctx->pos)
	370	ovl_dir_reset(file);
	371
	372	if (od->is_real)
	373	return iterate_dir(od->realfile, ctx);
	374
	375	if (!od->cache) {
	376	struct ovl_dir_cache *cache;
	377
	378	cache = ovl_cache_get(dentry);
	379	if (IS_ERR(cache))
	380	return PTR_ERR(cache);
	381
	382	od->cache = cache;
	383	ovl_seek_cursor(od, ctx->pos);
	384	}
	385
	386	while (od->cursor.l_node.next != &od->cache->entries) {
	387	struct ovl_cache_entry *p;
	388
	389	p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node);
	390	/* Skip cursors */
c2096537	391	if (!p->is_cursor) {
e9be9d5e MS	392	if (!p->is_whiteout) {
	393	if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
	394	break;
	395	}
	396	ctx->pos++;
	397	}
	398	list_move(&od->cursor.l_node, &p->l_node);
	399	}
	400	return 0;
	401	}
	402
	403	static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
	404	{
	405	loff_t res;
	406	struct ovl_dir_file *od = file->private_data;
	407
	408	mutex_lock(&file_inode(file)->i_mutex);
	409	if (!file->f_pos)
	410	ovl_dir_reset(file);
	411
	412	if (od->is_real) {
	413	res = vfs_llseek(od->realfile, offset, origin);
	414	file->f_pos = od->realfile->f_pos;
	415	} else {
	416	res = -EINVAL;
	417
	418	switch (origin) {
	419	case SEEK_CUR:
	420	offset += file->f_pos;
	421	break;
	422	case SEEK_SET:
	423	break;
	424	default:
	425	goto out_unlock;
	426	}
	427	if (offset < 0)
	428	goto out_unlock;
	429
	430	if (offset != file->f_pos) {
	431	file->f_pos = offset;
	432	if (od->cache)
	433	ovl_seek_cursor(od, offset);
	434	}
	435	res = offset;
	436	}
	437	out_unlock:
	438	mutex_unlock(&file_inode(file)->i_mutex);
	439
	440	return res;
	441	}
	442
	443	static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
	444	int datasync)
	445	{
	446	struct ovl_dir_file *od = file->private_data;
	447	struct dentry *dentry = file->f_path.dentry;
	448	struct file *realfile = od->realfile;
	449
	450	/*
	451	* Need to check if we started out being a lower dir, but got copied up
	452	*/
	453	if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) {
	454	struct inode *inode = file_inode(file);
	455
d45f00ae	456	realfile =lockless_dereference(od->upperfile);
e9be9d5e MS	457	if (!realfile) {
	458	struct path upperpath;
	459
	460	ovl_path_upper(dentry, &upperpath);
	461	realfile = ovl_path_open(&upperpath, O_RDONLY);
d45f00ae	462	smp_mb__before_spinlock();
3d268c9b AV	463	mutex_lock(&inode->i_mutex);
	464	if (!od->upperfile) {
	465	if (IS_ERR(realfile)) {
	466	mutex_unlock(&inode->i_mutex);
	467	return PTR_ERR(realfile);
	468	}
	469	od->upperfile = realfile;
	470	} else {
	471	/* somebody has beaten us to it */
	472	if (!IS_ERR(realfile))
	473	fput(realfile);
	474	realfile = od->upperfile;
e9be9d5e	475	}
3d268c9b	476	mutex_unlock(&inode->i_mutex);
e9be9d5e	477	}
e9be9d5e MS	478	}
	479
	480	return vfs_fsync_range(realfile, start, end, datasync);
	481	}
	482
	483	static int ovl_dir_release(struct inode inode, struct file file)
	484	{
	485	struct ovl_dir_file *od = file->private_data;
	486
	487	if (od->cache) {
	488	mutex_lock(&inode->i_mutex);
	489	ovl_cache_put(od, file->f_path.dentry);
	490	mutex_unlock(&inode->i_mutex);
	491	}
	492	fput(od->realfile);
	493	if (od->upperfile)
	494	fput(od->upperfile);
	495	kfree(od);
	496
	497	return 0;
	498	}
	499
	500	static int ovl_dir_open(struct inode inode, struct file file)
	501	{
	502	struct path realpath;
	503	struct file *realfile;
	504	struct ovl_dir_file *od;
	505	enum ovl_path_type type;
	506
	507	od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
	508	if (!od)
	509	return -ENOMEM;
	510
	511	type = ovl_path_real(file->f_path.dentry, &realpath);
	512	realfile = ovl_path_open(&realpath, file->f_flags);
	513	if (IS_ERR(realfile)) {
	514	kfree(od);
	515	return PTR_ERR(realfile);
	516	}
	517	INIT_LIST_HEAD(&od->cursor.l_node);
	518	od->realfile = realfile;
	519	od->is_real = (type != OVL_PATH_MERGE);
	520	od->is_upper = (type != OVL_PATH_LOWER);
c2096537	521	od->cursor.is_cursor = true;
e9be9d5e MS	522	file->private_data = od;
	523
	524	return 0;
	525	}
	526
	527	const struct file_operations ovl_dir_operations = {
	528	.read = generic_read_dir,
	529	.open = ovl_dir_open,
	530	.iterate = ovl_iterate,
	531	.llseek = ovl_dir_llseek,
	532	.fsync = ovl_dir_fsync,
	533	.release = ovl_dir_release,
	534	};
	535
	536	int ovl_check_empty_dir(struct dentry dentry, struct list_head list)
	537	{
	538	int err;
e9be9d5e MS	539	struct ovl_cache_entry *p;
e9be9d5e MS	540
c9f00fdb	541	err = ovl_dir_read_merged(dentry, list);
e9be9d5e MS	542	if (err)
	543	return err;
	544
	545	err = 0;
	546
	547	list_for_each_entry(p, list, l_node) {
	548	if (p->is_whiteout)
	549	continue;
	550
	551	if (p->name[0] == '.') {
	552	if (p->len == 1)
	553	continue;
	554	if (p->len == 2 && p->name[1] == '.')
	555	continue;
	556	}
	557	err = -ENOTEMPTY;
	558	break;
	559	}
	560
	561	return err;
	562	}
	563
	564	void ovl_cleanup_whiteouts(struct dentry upper, struct list_head list)
	565	{
	566	struct ovl_cache_entry *p;
	567
d1b72cc6	568	mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD);
e9be9d5e MS	569	list_for_each_entry(p, list, l_node) {
	570	struct dentry *dentry;
	571
	572	if (!p->is_whiteout)
	573	continue;
	574
	575	dentry = lookup_one_len(p->name, upper, p->len);
	576	if (IS_ERR(dentry)) {
	577	pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n",
	578	upper->d_name.name, p->len, p->name,
	579	(int) PTR_ERR(dentry));
	580	continue;
	581	}
	582	ovl_cleanup(upper->d_inode, dentry);
	583	dput(dentry);
	584	}
	585	mutex_unlock(&upper->d_inode->i_mutex);
	586	}