1/*
  2 * Copyright (C) 2011 Novell Inc.
  3 * Copyright (C) 2016 Red Hat, 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/mount.h>
 12#include <linux/slab.h>
 13#include <linux/xattr.h>
 14#include "overlayfs.h"
 15#include "ovl_entry.h"
 16
 17int ovl_want_write(struct dentry *dentry)
 18{
 19	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 20	return mnt_want_write(ofs->upper_mnt);
 21}
 22
 23void ovl_drop_write(struct dentry *dentry)
 24{
 25	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 26	mnt_drop_write(ofs->upper_mnt);
 27}
 28
 29struct dentry *ovl_workdir(struct dentry *dentry)
 30{
 31	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 32	return ofs->workdir;
 33}
 34
 35const struct cred *ovl_override_creds(struct super_block *sb)
 36{
 37	struct ovl_fs *ofs = sb->s_fs_info;
 38
 39	return override_creds(ofs->creator_cred);
 40}
 41
 42struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 43{
 44	size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
 45	struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
 46
 47	if (oe)
 48		oe->numlower = numlower;
 49
 50	return oe;
 51}
 52
 53bool ovl_dentry_remote(struct dentry *dentry)
 54{
 55	return dentry->d_flags &
 56		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
 57		 DCACHE_OP_REAL);
 58}
 59
 60bool ovl_dentry_weird(struct dentry *dentry)
 61{
 62	return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
 63				  DCACHE_MANAGE_TRANSIT |
 64				  DCACHE_OP_HASH |
 65				  DCACHE_OP_COMPARE);
 66}
 67
 68enum ovl_path_type ovl_path_type(struct dentry *dentry)
 69{
 70	struct ovl_entry *oe = dentry->d_fsdata;
 71	enum ovl_path_type type = 0;
 72
 73	if (oe->__upperdentry) {
 74		type = __OVL_PATH_UPPER;
 75
 76		/*
 77		 * Non-dir dentry can hold lower dentry from previous
 78		 * location.
 79		 */
 80		if (oe->numlower && d_is_dir(dentry))
 81			type |= __OVL_PATH_MERGE;
 82	} else {
 83		if (oe->numlower > 1)
 84			type |= __OVL_PATH_MERGE;
 85	}
 86	return type;
 87}
 88
 89void ovl_path_upper(struct dentry *dentry, struct path *path)
 90{
 91	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 92	struct ovl_entry *oe = dentry->d_fsdata;
 93
 94	path->mnt = ofs->upper_mnt;
 95	path->dentry = ovl_upperdentry_dereference(oe);
 96}
 97
 98void ovl_path_lower(struct dentry *dentry, struct path *path)
 99{
100	struct ovl_entry *oe = dentry->d_fsdata;
101
102	*path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
103}
104
105enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
106{
107	enum ovl_path_type type = ovl_path_type(dentry);
108
109	if (!OVL_TYPE_UPPER(type))
110		ovl_path_lower(dentry, path);
111	else
112		ovl_path_upper(dentry, path);
113
114	return type;
115}
116
117struct dentry *ovl_dentry_upper(struct dentry *dentry)
118{
119	struct ovl_entry *oe = dentry->d_fsdata;
120
121	return ovl_upperdentry_dereference(oe);
122}
123
124static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
125{
126	return oe->numlower ? oe->lowerstack[0].dentry : NULL;
127}
128
129struct dentry *ovl_dentry_lower(struct dentry *dentry)
130{
131	struct ovl_entry *oe = dentry->d_fsdata;
132
133	return __ovl_dentry_lower(oe);
134}
135
136struct dentry *ovl_dentry_real(struct dentry *dentry)
137{
138	struct ovl_entry *oe = dentry->d_fsdata;
139	struct dentry *realdentry;
140
141	realdentry = ovl_upperdentry_dereference(oe);
142	if (!realdentry)
143		realdentry = __ovl_dentry_lower(oe);
144
145	return realdentry;
146}
147
148struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
149{
150	struct ovl_entry *oe = dentry->d_fsdata;
151
152	return oe->cache;
153}
154
155void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
156{
157	struct ovl_entry *oe = dentry->d_fsdata;
158
159	oe->cache = cache;
160}
161
162bool ovl_dentry_is_opaque(struct dentry *dentry)
163{
164	struct ovl_entry *oe = dentry->d_fsdata;
165	return oe->opaque;
166}
167
168bool ovl_dentry_is_whiteout(struct dentry *dentry)
169{
170	return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
171}
172
173void ovl_dentry_set_opaque(struct dentry *dentry)
174{
175	struct ovl_entry *oe = dentry->d_fsdata;
176
177	oe->opaque = true;
178}
179
180bool ovl_redirect_dir(struct super_block *sb)
181{
182	struct ovl_fs *ofs = sb->s_fs_info;
183
184	return ofs->config.redirect_dir;
185}
186
187void ovl_clear_redirect_dir(struct super_block *sb)
188{
189	struct ovl_fs *ofs = sb->s_fs_info;
190
191	ofs->config.redirect_dir = false;
192}
193
194const char *ovl_dentry_get_redirect(struct dentry *dentry)
195{
196	struct ovl_entry *oe = dentry->d_fsdata;
197
198	return oe->redirect;
199}
200
201void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
202{
203	struct ovl_entry *oe = dentry->d_fsdata;
204
205	kfree(oe->redirect);
206	oe->redirect = redirect;
207}
208
209void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
210{
211	struct ovl_entry *oe = dentry->d_fsdata;
212
213	WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
214	WARN_ON(oe->__upperdentry);
215	/*
216	 * Make sure upperdentry is consistent before making it visible to
217	 * ovl_upperdentry_dereference().
218	 */
219	smp_wmb();
220	oe->__upperdentry = upperdentry;
221}
222
223void ovl_inode_init(struct inode *inode, struct inode *realinode, bool is_upper)
224{
225	WRITE_ONCE(inode->i_private, (unsigned long) realinode |
226		   (is_upper ? OVL_ISUPPER_MASK : 0));
227}
228
229void ovl_inode_update(struct inode *inode, struct inode *upperinode)
230{
231	WARN_ON(!upperinode);
232	WARN_ON(!inode_unhashed(inode));
233	WRITE_ONCE(inode->i_private,
234		   (unsigned long) upperinode | OVL_ISUPPER_MASK);
235	if (!S_ISDIR(upperinode->i_mode))
236		__insert_inode_hash(inode, (unsigned long) upperinode);
237}
238
239void ovl_dentry_version_inc(struct dentry *dentry)
240{
241	struct ovl_entry *oe = dentry->d_fsdata;
242
243	WARN_ON(!inode_is_locked(dentry->d_inode));
244	oe->version++;
245}
246
247u64 ovl_dentry_version_get(struct dentry *dentry)
248{
249	struct ovl_entry *oe = dentry->d_fsdata;
250
251	WARN_ON(!inode_is_locked(dentry->d_inode));
252	return oe->version;
253}
254
255bool ovl_is_whiteout(struct dentry *dentry)
256{
257	struct inode *inode = dentry->d_inode;
258
259	return inode && IS_WHITEOUT(inode);
260}
261
262struct file *ovl_path_open(struct path *path, int flags)
263{
264	return dentry_open(path, flags | O_NOATIME, current_cred());
265}