kernel/fs/btrfs/props.c

   1 /*
   2  * Copyright (C) 2014 Filipe David Borba Manana <fdmanana@gmail.com>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/hashtable.h>
  20 #include "props.h"
  21 #include "btrfs_inode.h"
  22 #include "hash.h"
  23 #include "transaction.h"
  24 #include "xattr.h"
  25
  26 #define BTRFS_PROP_HANDLERS_HT_BITS 8
  27 static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
  28
  29 struct prop_handler {
  30         struct hlist_node node;
  31         const char *xattr_name;
  32         int (*validate)(const char *value, size_t len);
  33         int (*apply)(struct inode *inode, const char *value, size_t len);
  34         const char *(*extract)(struct inode *inode);
  35         int inheritable;
  36 };
  37
  38 static int prop_compression_validate(const char *value, size_t len);
  39 static int prop_compression_apply(struct inode *inode,
  40                                   const char *value,
  41                                   size_t len);
  42 static const char *prop_compression_extract(struct inode *inode);
  43
  44 static struct prop_handler prop_handlers[] = {
  45         {
  46                 .xattr_name = XATTR_BTRFS_PREFIX "compression",
  47                 .validate = prop_compression_validate,
  48                 .apply = prop_compression_apply,
  49                 .extract = prop_compression_extract,
  50                 .inheritable = 1
  51         },
  52         {
  53                 .xattr_name = NULL
  54         }
  55 };
  56
  57 void __init btrfs_props_init(void)
  58 {
  59         struct prop_handler *p;
  60
  61         hash_init(prop_handlers_ht);
  62
  63         for (p = &prop_handlers[0]; p->xattr_name; p++) {
  64                 u64 h = btrfs_name_hash(p->xattr_name, strlen(p->xattr_name));
  65
  66                 hash_add(prop_handlers_ht, &p->node, h);
  67         }
  68 }
  69
  70 static const struct hlist_head *find_prop_handlers_by_hash(const u64 hash)
  71 {
  72         struct hlist_head *h;
  73
  74         h = &prop_handlers_ht[hash_min(hash, BTRFS_PROP_HANDLERS_HT_BITS)];
  75         if (hlist_empty(h))
  76                 return NULL;
  77
  78         return h;
  79 }
  80
  81 static const struct prop_handler *
  82 find_prop_handler(const char *name,
  83                   const struct hlist_head *handlers)
  84 {
  85         struct prop_handler *h;
  86
  87         if (!handlers) {
  88                 u64 hash = btrfs_name_hash(name, strlen(name));
  89
  90                 handlers = find_prop_handlers_by_hash(hash);
  91                 if (!handlers)
  92                         return NULL;
  93         }
  94
  95         hlist_for_each_entry(h, handlers, node)
  96                 if (!strcmp(h->xattr_name, name))
  97                         return h;
  98
  99         return NULL;
 100 }
 101
 102 static int __btrfs_set_prop(struct btrfs_trans_handle *trans,
 103                             struct inode *inode,
 104                             const char *name,
 105                             const char *value,
 106                             size_t value_len,
 107                             int flags)
 108 {
 109         const struct prop_handler *handler;
 110         int ret;
 111
 112         if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
 113                 return -EINVAL;
 114
 115         handler = find_prop_handler(name, NULL);
 116         if (!handler)
 117                 return -EINVAL;
 118
 119         if (value_len == 0) {
 120                 ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
 121                                        NULL, 0, flags);
 122                 if (ret)
 123                         return ret;
 124
 125                 ret = handler->apply(inode, NULL, 0);
 126                 ASSERT(ret == 0);
 127
 128                 return ret;
 129         }
 130
 131         ret = handler->validate(value, value_len);
 132         if (ret)
 133                 return ret;
 134         ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
 135                                value, value_len, flags);
 136         if (ret)
 137                 return ret;
 138         ret = handler->apply(inode, value, value_len);
 139         if (ret) {
 140                 __btrfs_setxattr(trans, inode, handler->xattr_name,
 141                                  NULL, 0, flags);
 142                 return ret;
 143         }
 144
 145         set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
 146
 147         return 0;
 148 }
 149
 150 int btrfs_set_prop(struct inode *inode,
 151                    const char *name,
 152                    const char *value,
 153                    size_t value_len,
 154                    int flags)
 155 {
 156         return __btrfs_set_prop(NULL, inode, name, value, value_len, flags);
 157 }
 158
 159 static int iterate_object_props(struct btrfs_root *root,
 160                                 struct btrfs_path *path,
 161                                 u64 objectid,
 162                                 void (*iterator)(void *,
 163                                                  const struct prop_handler *,
 164                                                  const char *,
 165                                                  size_t),
 166                                 void *ctx)
 167 {
 168         int ret;
 169         char *name_buf = NULL;
 170         char *value_buf = NULL;
 171         int name_buf_len = 0;
 172         int value_buf_len = 0;
 173
 174         while (1) {
 175                 struct btrfs_key key;
 176                 struct btrfs_dir_item *di;
 177                 struct extent_buffer *leaf;
 178                 u32 total_len, cur, this_len;
 179                 int slot;
 180                 const struct hlist_head *handlers;
 181
 182                 slot = path->slots[0];
 183                 leaf = path->nodes[0];
 184
 185                 if (slot >= btrfs_header_nritems(leaf)) {
 186                         ret = btrfs_next_leaf(root, path);
 187                         if (ret < 0)
 188                                 goto out;
 189                         else if (ret > 0)
 190                                 break;
 191                         continue;
 192                 }
 193
 194                 btrfs_item_key_to_cpu(leaf, &key, slot);
 195                 if (key.objectid != objectid)
 196                         break;
 197                 if (key.type != BTRFS_XATTR_ITEM_KEY)
 198                         break;
 199
 200                 handlers = find_prop_handlers_by_hash(key.offset);
 201                 if (!handlers)
 202                         goto next_slot;
 203
 204                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
 205                 cur = 0;
 206                 total_len = btrfs_item_size_nr(leaf, slot);
 207
 208                 while (cur < total_len) {
 209                         u32 name_len = btrfs_dir_name_len(leaf, di);
 210                         u32 data_len = btrfs_dir_data_len(leaf, di);
 211                         unsigned long name_ptr, data_ptr;
 212                         const struct prop_handler *handler;
 213
 214                         this_len = sizeof(*di) + name_len + data_len;
 215                         name_ptr = (unsigned long)(di + 1);
 216                         data_ptr = name_ptr + name_len;
 217
 218                         if (name_len <= XATTR_BTRFS_PREFIX_LEN ||
 219                             memcmp_extent_buffer(leaf, XATTR_BTRFS_PREFIX,
 220                                                  name_ptr,
 221                                                  XATTR_BTRFS_PREFIX_LEN))
 222                                 goto next_dir_item;
 223
 224                         if (name_len >= name_buf_len) {
 225                                 kfree(name_buf);
 226                                 name_buf_len = name_len + 1;
 227                                 name_buf = kmalloc(name_buf_len, GFP_NOFS);
 228                                 if (!name_buf) {
 229                                         ret = -ENOMEM;
 230                                         goto out;
 231                                 }
 232                         }
 233                         read_extent_buffer(leaf, name_buf, name_ptr, name_len);
 234                         name_buf[name_len] = '\0';
 235
 236                         handler = find_prop_handler(name_buf, handlers);
 237                         if (!handler)
 238                                 goto next_dir_item;
 239
 240                         if (data_len > value_buf_len) {
 241                                 kfree(value_buf);
 242                                 value_buf_len = data_len;
 243                                 value_buf = kmalloc(data_len, GFP_NOFS);
 244                                 if (!value_buf) {
 245                                         ret = -ENOMEM;
 246                                         goto out;
 247                                 }
 248                         }
 249                         read_extent_buffer(leaf, value_buf, data_ptr, data_len);
 250
 251                         iterator(ctx, handler, value_buf, data_len);
 252 next_dir_item:
 253                         cur += this_len;
 254                         di = (struct btrfs_dir_item *)((char *) di + this_len);
 255                 }
 256
 257 next_slot:
 258                 path->slots[0]++;
 259         }
 260
 261         ret = 0;
 262 out:
 263         btrfs_release_path(path);
 264         kfree(name_buf);
 265         kfree(value_buf);
 266
 267         return ret;
 268 }
 269
 270 static void inode_prop_iterator(void *ctx,
 271                                 const struct prop_handler *handler,
 272                                 const char *value,
 273                                 size_t len)
 274 {
 275         struct inode *inode = ctx;
 276         struct btrfs_root *root = BTRFS_I(inode)->root;
 277         int ret;
 278
 279         ret = handler->apply(inode, value, len);
 280         if (unlikely(ret))
 281                 btrfs_warn(root->fs_info,
 282                            "error applying prop %s to ino %llu (root %llu): %d",
 283                            handler->xattr_name, btrfs_ino(inode),
 284                            root->root_key.objectid, ret);
 285         else
 286                 set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
 287 }
 288
 289 int btrfs_load_inode_props(struct inode *inode, struct btrfs_path *path)
 290 {
 291         struct btrfs_root *root = BTRFS_I(inode)->root;
 292         u64 ino = btrfs_ino(inode);
 293         int ret;
 294
 295         ret = iterate_object_props(root, path, ino, inode_prop_iterator, inode);
 296
 297         return ret;
 298 }
 299
 300 static int inherit_props(struct btrfs_trans_handle *trans,
 301                          struct inode *inode,
 302                          struct inode *parent)
 303 {
 304         const struct prop_handler *h;
 305         struct btrfs_root *root = BTRFS_I(inode)->root;
 306         int ret;
 307
 308         if (!test_bit(BTRFS_INODE_HAS_PROPS,
 309                       &BTRFS_I(parent)->runtime_flags))
 310                 return 0;
 311
 312         for (h = &prop_handlers[0]; h->xattr_name; h++) {
 313                 const char *value;
 314                 u64 num_bytes;
 315
 316                 if (!h->inheritable)
 317                         continue;
 318
 319                 value = h->extract(parent);
 320                 if (!value)
 321                         continue;
 322
 323                 num_bytes = btrfs_calc_trans_metadata_size(root, 1);
 324                 ret = btrfs_block_rsv_add(root, trans->block_rsv,
 325                                           num_bytes, BTRFS_RESERVE_NO_FLUSH);
 326                 if (ret)
 327                         goto out;
 328                 ret = __btrfs_set_prop(trans, inode, h->xattr_name,
 329                                        value, strlen(value), 0);
 330                 btrfs_block_rsv_release(root, trans->block_rsv, num_bytes);
 331                 if (ret)
 332                         goto out;
 333         }
 334         ret = 0;
 335 out:
 336         return ret;
 337 }
 338
 339 int btrfs_inode_inherit_props(struct btrfs_trans_handle *trans,
 340                               struct inode *inode,
 341                               struct inode *dir)
 342 {
 343         if (!dir)
 344                 return 0;
 345
 346         return inherit_props(trans, inode, dir);
 347 }
 348
 349 int btrfs_subvol_inherit_props(struct btrfs_trans_handle *trans,
 350                                struct btrfs_root *root,
 351                                struct btrfs_root *parent_root)
 352 {
 353         struct btrfs_key key;
 354         struct inode *parent_inode, *child_inode;
 355         int ret;
 356
 357         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 358         key.type = BTRFS_INODE_ITEM_KEY;
 359         key.offset = 0;
 360
 361         parent_inode = btrfs_iget(parent_root->fs_info->sb, &key,
 362                                   parent_root, NULL);
 363         if (IS_ERR(parent_inode))
 364                 return PTR_ERR(parent_inode);
 365
 366         child_inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
 367         if (IS_ERR(child_inode)) {
 368                 iput(parent_inode);
 369                 return PTR_ERR(child_inode);
 370         }
 371
 372         ret = inherit_props(trans, child_inode, parent_inode);
 373         iput(child_inode);
 374         iput(parent_inode);
 375
 376         return ret;
 377 }
 378
 379 static int prop_compression_validate(const char *value, size_t len)
 380 {
 381         if (!strncmp("lzo", value, len))
 382                 return 0;
 383         else if (!strncmp("zlib", value, len))
 384                 return 0;
 385
 386         return -EINVAL;
 387 }
 388
 389 static int prop_compression_apply(struct inode *inode,
 390                                   const char *value,
 391                                   size_t len)
 392 {
 393         int type;
 394
 395         if (len == 0) {
 396                 BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
 397                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
 398                 BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_NONE;
 399
 400                 return 0;
 401         }
 402
 403         if (!strncmp("lzo", value, len))
 404                 type = BTRFS_COMPRESS_LZO;
 405         else if (!strncmp("zlib", value, len))
 406                 type = BTRFS_COMPRESS_ZLIB;
 407         else
 408                 return -EINVAL;
 409
 410         BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
 411         BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
 412         BTRFS_I(inode)->force_compress = type;
 413
 414         return 0;
 415 }
 416
 417 static const char *prop_compression_extract(struct inode *inode)
 418 {
 419         switch (BTRFS_I(inode)->force_compress) {
 420         case BTRFS_COMPRESS_ZLIB:
 421                 return "zlib";
 422         case BTRFS_COMPRESS_LZO:
 423                 return "lzo";
 424         }
 425
 426         return NULL;
 427 }
 428
 429