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 17 int 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 23 void 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 29 struct dentry *ovl_workdir(struct dentry *dentry) 30 { 31 struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 32 return ofs->workdir; 33 } 34 35 const 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 42 struct 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 53 bool 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 60 bool 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 68 enum 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 89 void 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 98 void 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 } 104 105 enum 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 } 116 117 struct dentry *ovl_dentry_upper(struct dentry *dentry) 118 { 119 struct ovl_entry *oe = dentry->d_fsdata; 120 121 return ovl_upperdentry_dereference(oe); 122 } 123 124 static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe) 125 { 126 return oe->numlower ? oe->lowerstack[0].dentry : NULL; 127 } 128 129 struct dentry *ovl_dentry_lower(struct dentry *dentry) 130 { 131 struct ovl_entry *oe = dentry->d_fsdata; 132 133 return __ovl_dentry_lower(oe); 134 } 135 136 struct 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 } 147 148 struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) 149 { 150 struct ovl_entry *oe = dentry->d_fsdata; 151 152 return oe->cache; 153 } 154 155 void 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 } 161 162 bool ovl_dentry_is_opaque(struct dentry *dentry) 163 { 164 struct ovl_entry *oe = dentry->d_fsdata; 165 return oe->opaque; 166 } 167 168 bool ovl_dentry_is_whiteout(struct dentry *dentry) 169 { 170 return !dentry->d_inode && ovl_dentry_is_opaque(dentry); 171 } 172 173 void ovl_dentry_set_opaque(struct dentry *dentry) 174 { 175 struct ovl_entry *oe = dentry->d_fsdata; 176 177 oe->opaque = true; 178 } 179 180 bool 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 } 186 187 void 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 } 193 194 const char *ovl_dentry_get_redirect(struct dentry *dentry) 195 { 196 struct ovl_entry *oe = dentry->d_fsdata; 197 198 return oe->redirect; 199 } 200 201 void 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 } 208 209 void 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 } 222 223 void 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 } 228 229 void 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 } 238 239 void 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 } 246 247 u64 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 } 254 255 bool ovl_is_whiteout(struct dentry *dentry) 256 { 257 struct inode *inode = dentry->d_inode; 258 259 return inode && IS_WHITEOUT(inode); 260 } 261 262 struct file *ovl_path_open(struct path *path, int flags) 263 { 264 return dentry_open(path, flags | O_NOATIME, current_cred()); 265 } 266