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