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 #include "compression.h"
  26
  27 #define BTRFS_PROP_HANDLERS_HT_BITS 8
  28 static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
  29
  30 struct prop_handler {
  31         struct hlist_node node;
  32         const char *xattr_name;
  33         int (*validate)(const char *value, size_t len);
  34         int (*apply)(struct inode *inode, const char *value, size_t len);
  35         const char *(*extract)(struct inode *inode);
  36         int inheritable;
  37 };
  38
  39 static int prop_compression_validate(const char *value, size_t len);
  40 static int prop_compression_apply(struct inode *inode,
  41                                   const char *value,
  42                                   size_t len);
  43 static const char *prop_compression_extract(struct inode *inode);
  44
  45 static struct prop_handler prop_handlers[] = {
  46         {
  47                 .xattr_name = XATTR_BTRFS_PREFIX "compression",
  48                 .validate = prop_compression_validate,
  49                 .apply = prop_compression_apply,
  50                 .extract = prop_compression_extract,
  51                 .inheritable = 1
  52         },
  53 };
  54
  55 void __init btrfs_props_init(void)
  56 {
  57         int i;
  58
  59         hash_init(prop_handlers_ht);
  60
  61         for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
  62                 struct prop_handler *p = &prop_handlers[i];
  63                 u64 h = btrfs_name_hash(p->xattr_name, strlen(p->xattr_name));
  64
  65                 hash_add(prop_handlers_ht, &p->node, h);
  66         }
  67 }
  68
  69 static const struct hlist_head *find_prop_handlers_by_hash(const u64 hash)
  70 {
  71         struct hlist_head *h;
  72
  73         h = &prop_handlers_ht[hash_min(hash, BTRFS_PROP_HANDLERS_HT_BITS)];
  74         if (hlist_empty(h))
  75                 return NULL;
  76
  77         return h;
  78 }
  79
  80 static const struct prop_handler *
  81 find_prop_handler(const char *name,
  82                   const struct hlist_head *handlers)
  83 {
  84         struct prop_handler *h;
  85
  86         if (!handlers) {
  87                 u64 hash = btrfs_name_hash(name, strlen(name));
  88
  89                 handlers = find_prop_handlers_by_hash(hash);
  90                 if (!handlers)
  91                         return NULL;
  92         }
  93
  94         hlist_for_each_entry(h, handlers, node)
  95                 if (!strcmp(h->xattr_name, name))
  96                         return h;
  97
  98         return NULL;
  99 }
 100
 101 static int __btrfs_set_prop(struct btrfs_trans_handle *trans,
 102                             struct inode *inode,
 103                             const char *name,
 104                             const char *value,
 105                             size_t value_len,
 106                             int flags)
 107 {
 108         const struct prop_handler *handler;
 109         int ret;
 110
 111         if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
 112                 return -EINVAL;
 113
 114         handler = find_prop_handler(name, NULL);
 115         if (!handler)
 116                 return -EINVAL;
 117
 118         if (value_len == 0) {
 119                 ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
 120                                        NULL, 0, flags);
 121                 if (ret)
 122                         return ret;
 123
 124                 ret = handler->apply(inode, NULL, 0);
 125                 ASSERT(ret == 0);
 126
 127                 return ret;
 128         }
 129
 130         ret = handler->validate(value, value_len);
 131         if (ret)
 132                 return ret;
 133         ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
 134                                value, value_len, flags);
 135         if (ret)
 136                 return ret;
 137         ret = handler->apply(inode, value, value_len);
 138         if (ret) {
 139                 __btrfs_setxattr(trans, inode, handler->xattr_name,
 140                                  NULL, 0, flags);
 141                 return ret;
 142         }
 143
 144         set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
 145
 146         return 0;
 147 }
 148
 149 int btrfs_set_prop(struct inode *inode,
 150                    const char *name,
 151                    const char *value,
 152                    size_t value_len,
 153                    int flags)
 154 {
 155         return __btrfs_set_prop(NULL, inode, name, value, value_len, flags);
 156 }
 157
 158 static int iterate_object_props(struct btrfs_root *root,
 159                                 struct btrfs_path *path,
 160                                 u64 objectid,
 161                                 void (*iterator)(void *,
 162                                                  const struct prop_handler *,
 163                                                  const char *,
 164                                                  size_t),
 165                                 void *ctx)
 166 {
 167         int ret;
 168         char *name_buf = NULL;
 169         char *value_buf = NULL;
 170         int name_buf_len = 0;
 171         int value_buf_len = 0;
 172
 173         while (1) {
 174                 struct btrfs_key key;
 175                 struct btrfs_dir_item *di;
 176                 struct extent_buffer *leaf;
 177                 u32 total_len, cur, this_len;
 178                 int slot;
 179                 const struct hlist_head *handlers;
 180
 181                 slot = path->slots[0];
 182                 leaf = path->nodes[0];
 183
 184                 if (slot >= btrfs_header_nritems(leaf)) {
 185                         ret = btrfs_next_leaf(root, path);
 186                         if (ret < 0)
 187                                 goto out;
 188                         else if (ret > 0)
 189                                 break;
 190                         continue;
 191                 }
 192
 193                 btrfs_item_key_to_cpu(leaf, &key, slot);
 194                 if (key.objectid != objectid)
 195                         break;
 196                 if (key.type != BTRFS_XATTR_ITEM_KEY)
 197                         break;
 198
 199                 handlers = find_prop_handlers_by_hash(key.offset);
 200                 if (!handlers)
 201                         goto next_slot;
 202
 203                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
 204                 cur = 0;
 205                 total_len = btrfs_item_size_nr(leaf, slot);
 206
 207                 while (cur < total_len) {
 208                         u32 name_len = btrfs_dir_name_len(leaf, di);
 209                         u32 data_len = btrfs_dir_data_len(leaf, di);
 210                         unsigned long name_ptr, data_ptr;
 211                         const struct prop_handler *handler;
 212
 213                         this_len = sizeof(*di) + name_len + data_len;
 214                         name_ptr = (unsigned long)(di + 1);
 215                         data_ptr = name_ptr + name_len;
 216
 217                         if (name_len <= XATTR_BTRFS_PREFIX_LEN ||
 218                             memcmp_extent_buffer(leaf, XATTR_BTRFS_PREFIX,
 219                                                  name_ptr,
 220                                                  XATTR_BTRFS_PREFIX_LEN))
 221                                 goto next_dir_item;
 222
 223                         if (name_len >= name_buf_len) {
 224                                 kfree(name_buf);
 225                                 name_buf_len = name_len + 1;
 226                                 name_buf = kmalloc(name_buf_len, GFP_NOFS);
 227                                 if (!name_buf) {
 228                                         ret = -ENOMEM;
 229                                         goto out;
 230                                 }
 231                         }
 232                         read_extent_buffer(leaf, name_buf, name_ptr, name_len);
 233                         name_buf[name_len] = '\0';
 234
 235                         handler = find_prop_handler(name_buf, handlers);
 236                         if (!handler)
 237                                 goto next_dir_item;
 238
 239                         if (data_len > value_buf_len) {
 240                                 kfree(value_buf);
 241                                 value_buf_len = data_len;
 242                                 value_buf = kmalloc(data_len, GFP_NOFS);
 243                                 if (!value_buf) {
 244                                         ret = -ENOMEM;
 245                                         goto out;
 246                                 }
 247                         }
 248                         read_extent_buffer(leaf, value_buf, data_ptr, data_len);
 249
 250                         iterator(ctx, handler, value_buf, data_len);
 251 next_dir_item:
 252                         cur += this_len;
 253                         di = (struct btrfs_dir_item *)((char *) di + this_len);
 254                 }
 255
 256 next_slot:
 257                 path->slots[0]++;
 258         }
 259
 260         ret = 0;
 261 out:
 262         btrfs_release_path(path);
 263         kfree(name_buf);
 264         kfree(value_buf);
 265
 266         return ret;
 267 }
 268
 269 static void inode_prop_iterator(void *ctx,
 270                                 const struct prop_handler *handler,
 271                                 const char *value,
 272                                 size_t len)
 273 {
 274         struct inode *inode = ctx;
 275         struct btrfs_root *root = BTRFS_I(inode)->root;
 276         int ret;
 277
 278         ret = handler->apply(inode, value, len);
 279         if (unlikely(ret))
 280                 btrfs_warn(root->fs_info,
 281                            "error applying prop %s to ino %llu (root %llu): %d",
 282                            handler->xattr_name, btrfs_ino(BTRFS_I(inode)),
 283                            root->root_key.objectid, ret);
 284         else
 285                 set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
 286 }
 287
 288 int btrfs_load_inode_props(struct inode *inode, struct btrfs_path *path)
 289 {
 290         struct btrfs_root *root = BTRFS_I(inode)->root;
 291         u64 ino = btrfs_ino(BTRFS_I(inode));
 292         int ret;
 293
 294         ret = iterate_object_props(root, path, ino, inode_prop_iterator, inode);
 295
 296         return ret;
 297 }
 298
 299 static int inherit_props(struct btrfs_trans_handle *trans,
 300                          struct inode *inode,
 301                          struct inode *parent)
 302 {
 303         struct btrfs_root *root = BTRFS_I(inode)->root;
 304         struct btrfs_fs_info *fs_info = root->fs_info;
 305         int ret;
 306         int i;
 307
 308         if (!test_bit(BTRFS_INODE_HAS_PROPS,
 309                       &BTRFS_I(parent)->runtime_flags))
 310                 return 0;
 311
 312         for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
 313                 const struct prop_handler *h = &prop_handlers[i];
 314                 const char *value;
 315                 u64 num_bytes;
 316
 317                 if (!h->inheritable)
 318                         continue;
 319
 320                 value = h->extract(parent);
 321                 if (!value)
 322                         continue;
 323
 324                 num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
 325                 ret = btrfs_block_rsv_add(root, trans->block_rsv,
 326                                           num_bytes, BTRFS_RESERVE_NO_FLUSH);
 327                 if (ret)
 328                         goto out;
 329                 ret = __btrfs_set_prop(trans, inode, h->xattr_name,
 330                                        value, strlen(value), 0);
 331                 btrfs_block_rsv_release(fs_info, trans->block_rsv, num_bytes);
 332                 if (ret)
 333                         goto out;
 334         }
 335         ret = 0;
 336 out:
 337         return ret;
 338 }
 339
 340 int btrfs_inode_inherit_props(struct btrfs_trans_handle *trans,
 341                               struct inode *inode,
 342                               struct inode *dir)
 343 {
 344         if (!dir)
 345                 return 0;
 346
 347         return inherit_props(trans, inode, dir);
 348 }
 349
 350 int btrfs_subvol_inherit_props(struct btrfs_trans_handle *trans,
 351                                struct btrfs_root *root,
 352                                struct btrfs_root *parent_root)
 353 {
 354         struct super_block *sb = root->fs_info->sb;
 355         struct btrfs_key key;
 356         struct inode *parent_inode, *child_inode;
 357         int ret;
 358
 359         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 360         key.type = BTRFS_INODE_ITEM_KEY;
 361         key.offset = 0;
 362
 363         parent_inode = btrfs_iget(sb, &key, parent_root, NULL);
 364         if (IS_ERR(parent_inode))
 365                 return PTR_ERR(parent_inode);
 366
 367         child_inode = btrfs_iget(sb, &key, root, NULL);
 368         if (IS_ERR(child_inode)) {
 369                 iput(parent_inode);
 370                 return PTR_ERR(child_inode);
 371         }
 372
 373         ret = inherit_props(trans, child_inode, parent_inode);
 374         iput(child_inode);
 375         iput(parent_inode);
 376
 377         return ret;
 378 }
 379
 380 static int prop_compression_validate(const char *value, size_t len)
 381 {
 382         if (!strncmp("lzo", value, len))
 383                 return 0;
 384         else if (!strncmp("zlib", value, len))
 385                 return 0;
 386
 387         return -EINVAL;
 388 }
 389
 390 static int prop_compression_apply(struct inode *inode,
 391                                   const char *value,
 392                                   size_t len)
 393 {
 394         int type;
 395
 396         if (len == 0) {
 397                 BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
 398                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
 399                 BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_NONE;
 400
 401                 return 0;
 402         }
 403
 404         if (!strncmp("lzo", value, len))
 405                 type = BTRFS_COMPRESS_LZO;
 406         else if (!strncmp("zlib", value, len))
 407                 type = BTRFS_COMPRESS_ZLIB;
 408         else
 409                 return -EINVAL;
 410
 411         BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
 412         BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
 413         BTRFS_I(inode)->force_compress = type;
 414
 415         return 0;
 416 }
 417
 418 static const char *prop_compression_extract(struct inode *inode)
 419 {
 420         switch (BTRFS_I(inode)->force_compress) {
 421         case BTRFS_COMPRESS_ZLIB:
 422                 return "zlib";
 423         case BTRFS_COMPRESS_LZO:
 424                 return "lzo";
 425         }
 426
 427         return NULL;
 428 }
 429
 430