fs/btrfs/inode-item.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include "ctree.h"
   7 #include "fs.h"
   8 #include "messages.h"
   9 #include "inode-item.h"
  10 #include "disk-io.h"
  11 #include "transaction.h"
  12 #include "space-info.h"
  13 #include "accessors.h"
  14 #include "extent-tree.h"
  15 #include "file-item.h"
  16
  17 struct btrfs_inode_ref *btrfs_find_name_in_backref(const struct extent_buffer *leaf,
  18                                                    int slot,
  19                                                    const struct fscrypt_str *name)
  20 {
  21         struct btrfs_inode_ref *ref;
  22         unsigned long ptr;
  23         unsigned long name_ptr;
  24         u32 item_size;
  25         u32 cur_offset = 0;
  26         int len;
  27
  28         item_size = btrfs_item_size(leaf, slot);
  29         ptr = btrfs_item_ptr_offset(leaf, slot);
  30         while (cur_offset < item_size) {
  31                 ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
  32                 len = btrfs_inode_ref_name_len(leaf, ref);
  33                 name_ptr = (unsigned long)(ref + 1);
  34                 cur_offset += len + sizeof(*ref);
  35                 if (len != name->len)
  36                         continue;
  37                 if (memcmp_extent_buffer(leaf, name->name, name_ptr,
  38                                          name->len) == 0)
  39                         return ref;
  40         }
  41         return NULL;
  42 }
  43
  44 struct btrfs_inode_extref *btrfs_find_name_in_ext_backref(
  45                 const struct extent_buffer *leaf, int slot, u64 ref_objectid,
  46                 const struct fscrypt_str *name)
  47 {
  48         struct btrfs_inode_extref *extref;
  49         unsigned long ptr;
  50         unsigned long name_ptr;
  51         u32 item_size;
  52         u32 cur_offset = 0;
  53         int ref_name_len;
  54
  55         item_size = btrfs_item_size(leaf, slot);
  56         ptr = btrfs_item_ptr_offset(leaf, slot);
  57
  58         /*
  59          * Search all extended backrefs in this item. We're only
  60          * looking through any collisions so most of the time this is
  61          * just going to compare against one buffer. If all is well,
  62          * we'll return success and the inode ref object.
  63          */
  64         while (cur_offset < item_size) {
  65                 extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
  66                 name_ptr = (unsigned long)(&extref->name);
  67                 ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
  68
  69                 if (ref_name_len == name->len &&
  70                     btrfs_inode_extref_parent(leaf, extref) == ref_objectid &&
  71                     (memcmp_extent_buffer(leaf, name->name, name_ptr,
  72                                           name->len) == 0))
  73                         return extref;
  74
  75                 cur_offset += ref_name_len + sizeof(*extref);
  76         }
  77         return NULL;
  78 }
  79
  80 /* Returns NULL if no extref found */
  81 struct btrfs_inode_extref *
  82 btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
  83                           struct btrfs_root *root,
  84                           struct btrfs_path *path,
  85                           const struct fscrypt_str *name,
  86                           u64 inode_objectid, u64 ref_objectid, int ins_len,
  87                           int cow)
  88 {
  89         int ret;
  90         struct btrfs_key key;
  91
  92         key.objectid = inode_objectid;
  93         key.type = BTRFS_INODE_EXTREF_KEY;
  94         key.offset = btrfs_extref_hash(ref_objectid, name->name, name->len);
  95
  96         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
  97         if (ret < 0)
  98                 return ERR_PTR(ret);
  99         if (ret > 0)
 100                 return NULL;
 101         return btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
 102                                               ref_objectid, name);
 103
 104 }
 105
 106 static int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
 107                                   struct btrfs_root *root,
 108                                   const struct fscrypt_str *name,
 109                                   u64 inode_objectid, u64 ref_objectid,
 110                                   u64 *index)
 111 {
 112         BTRFS_PATH_AUTO_FREE(path);
 113         struct btrfs_key key;
 114         struct btrfs_inode_extref *extref;
 115         struct extent_buffer *leaf;
 116         int ret;
 117         int del_len = name->len + sizeof(*extref);
 118         unsigned long ptr;
 119         unsigned long item_start;
 120         u32 item_size;
 121
 122         key.objectid = inode_objectid;
 123         key.type = BTRFS_INODE_EXTREF_KEY;
 124         key.offset = btrfs_extref_hash(ref_objectid, name->name, name->len);
 125
 126         path = btrfs_alloc_path();
 127         if (!path)
 128                 return -ENOMEM;
 129
 130         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 131         if (ret > 0)
 132                 return -ENOENT;
 133         if (ret < 0)
 134                 return ret;
 135
 136         /*
 137          * Sanity check - did we find the right item for this name?
 138          * This should always succeed so error here will make the FS
 139          * readonly.
 140          */
 141         extref = btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
 142                                                 ref_objectid, name);
 143         if (!extref) {
 144                 btrfs_abort_transaction(trans, -ENOENT);
 145                 return -ENOENT;
 146         }
 147
 148         leaf = path->nodes[0];
 149         item_size = btrfs_item_size(leaf, path->slots[0]);
 150         if (index)
 151                 *index = btrfs_inode_extref_index(leaf, extref);
 152
 153         if (del_len == item_size) {
 154                 /* Common case only one ref in the item, remove the whole item. */
 155                 return btrfs_del_item(trans, root, path);
 156         }
 157
 158         ptr = (unsigned long)extref;
 159         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 160
 161         memmove_extent_buffer(leaf, ptr, ptr + del_len,
 162                               item_size - (ptr + del_len - item_start));
 163
 164         btrfs_truncate_item(trans, path, item_size - del_len, 1);
 165
 166         return ret;
 167 }
 168
 169 int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
 170                         struct btrfs_root *root, const struct fscrypt_str *name,
 171                         u64 inode_objectid, u64 ref_objectid, u64 *index)
 172 {
 173         struct btrfs_path *path;
 174         struct btrfs_key key;
 175         struct btrfs_inode_ref *ref;
 176         struct extent_buffer *leaf;
 177         unsigned long ptr;
 178         unsigned long item_start;
 179         u32 item_size;
 180         u32 sub_item_len;
 181         int ret;
 182         int search_ext_refs = 0;
 183         int del_len = name->len + sizeof(*ref);
 184
 185         key.objectid = inode_objectid;
 186         key.type = BTRFS_INODE_REF_KEY;
 187         key.offset = ref_objectid;
 188
 189         path = btrfs_alloc_path();
 190         if (!path)
 191                 return -ENOMEM;
 192
 193         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 194         if (ret > 0) {
 195                 ret = -ENOENT;
 196                 search_ext_refs = 1;
 197                 goto out;
 198         } else if (ret < 0) {
 199                 goto out;
 200         }
 201
 202         ref = btrfs_find_name_in_backref(path->nodes[0], path->slots[0], name);
 203         if (!ref) {
 204                 ret = -ENOENT;
 205                 search_ext_refs = 1;
 206                 goto out;
 207         }
 208         leaf = path->nodes[0];
 209         item_size = btrfs_item_size(leaf, path->slots[0]);
 210
 211         if (index)
 212                 *index = btrfs_inode_ref_index(leaf, ref);
 213
 214         if (del_len == item_size) {
 215                 ret = btrfs_del_item(trans, root, path);
 216                 goto out;
 217         }
 218         ptr = (unsigned long)ref;
 219         sub_item_len = name->len + sizeof(*ref);
 220         item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 221         memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 222                               item_size - (ptr + sub_item_len - item_start));
 223         btrfs_truncate_item(trans, path, item_size - sub_item_len, 1);
 224 out:
 225         btrfs_free_path(path);
 226
 227         if (search_ext_refs) {
 228                 /*
 229                  * No refs were found, or we could not find the
 230                  * name in our ref array. Find and remove the extended
 231                  * inode ref then.
 232                  */
 233                 return btrfs_del_inode_extref(trans, root, name,
 234                                               inode_objectid, ref_objectid, index);
 235         }
 236
 237         return ret;
 238 }
 239
 240 /*
 241  * Insert an extended inode ref into a tree.
 242  *
 243  * The caller must have checked against BTRFS_LINK_MAX already.
 244  */
 245 static int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
 246                                      struct btrfs_root *root,
 247                                      const struct fscrypt_str *name,
 248                                      u64 inode_objectid, u64 ref_objectid,
 249                                      u64 index)
 250 {
 251         struct btrfs_inode_extref *extref;
 252         int ret;
 253         int ins_len = name->len + sizeof(*extref);
 254         unsigned long ptr;
 255         BTRFS_PATH_AUTO_FREE(path);
 256         struct btrfs_key key;
 257         struct extent_buffer *leaf;
 258
 259         key.objectid = inode_objectid;
 260         key.type = BTRFS_INODE_EXTREF_KEY;
 261         key.offset = btrfs_extref_hash(ref_objectid, name->name, name->len);
 262
 263         path = btrfs_alloc_path();
 264         if (!path)
 265                 return -ENOMEM;
 266
 267         ret = btrfs_insert_empty_item(trans, root, path, &key,
 268                                       ins_len);
 269         if (ret == -EEXIST) {
 270                 if (btrfs_find_name_in_ext_backref(path->nodes[0],
 271                                                    path->slots[0],
 272                                                    ref_objectid,
 273                                                    name))
 274                         return ret;
 275
 276                 btrfs_extend_item(trans, path, ins_len);
 277                 ret = 0;
 278         }
 279         if (ret < 0)
 280                 return ret;
 281
 282         leaf = path->nodes[0];
 283         ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
 284         ptr += btrfs_item_size(leaf, path->slots[0]) - ins_len;
 285         extref = (struct btrfs_inode_extref *)ptr;
 286
 287         btrfs_set_inode_extref_name_len(path->nodes[0], extref, name->len);
 288         btrfs_set_inode_extref_index(path->nodes[0], extref, index);
 289         btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);
 290
 291         ptr = (unsigned long)&extref->name;
 292         write_extent_buffer(path->nodes[0], name->name, ptr, name->len);
 293
 294         return 0;
 295 }
 296
 297 /* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
 298 int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
 299                            struct btrfs_root *root, const struct fscrypt_str *name,
 300                            u64 inode_objectid, u64 ref_objectid, u64 index)
 301 {
 302         struct btrfs_fs_info *fs_info = root->fs_info;
 303         struct btrfs_path *path;
 304         struct btrfs_key key;
 305         struct btrfs_inode_ref *ref;
 306         unsigned long ptr;
 307         int ret;
 308         int ins_len = name->len + sizeof(*ref);
 309
 310         key.objectid = inode_objectid;
 311         key.type = BTRFS_INODE_REF_KEY;
 312         key.offset = ref_objectid;
 313
 314         path = btrfs_alloc_path();
 315         if (!path)
 316                 return -ENOMEM;
 317
 318         path->skip_release_on_error = 1;
 319         ret = btrfs_insert_empty_item(trans, root, path, &key,
 320                                       ins_len);
 321         if (ret == -EEXIST) {
 322                 u32 old_size;
 323                 ref = btrfs_find_name_in_backref(path->nodes[0], path->slots[0],
 324                                                  name);
 325                 if (ref)
 326                         goto out;
 327
 328                 old_size = btrfs_item_size(path->nodes[0], path->slots[0]);
 329                 btrfs_extend_item(trans, path, ins_len);
 330                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 331                                      struct btrfs_inode_ref);
 332                 ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
 333                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name->len);
 334                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 335                 ptr = (unsigned long)(ref + 1);
 336                 ret = 0;
 337         } else if (ret < 0) {
 338                 if (ret == -EOVERFLOW) {
 339                         if (btrfs_find_name_in_backref(path->nodes[0],
 340                                                        path->slots[0],
 341                                                        name))
 342                                 ret = -EEXIST;
 343                         else
 344                                 ret = -EMLINK;
 345                 }
 346                 goto out;
 347         } else {
 348                 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 349                                      struct btrfs_inode_ref);
 350                 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name->len);
 351                 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
 352                 ptr = (unsigned long)(ref + 1);
 353         }
 354         write_extent_buffer(path->nodes[0], name->name, ptr, name->len);
 355 out:
 356         btrfs_free_path(path);
 357
 358         if (ret == -EMLINK) {
 359                 struct btrfs_super_block *disk_super = fs_info->super_copy;
 360                 /* We ran out of space in the ref array. Need to
 361                  * add an extended ref. */
 362                 if (btrfs_super_incompat_flags(disk_super)
 363                     & BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
 364                         ret = btrfs_insert_inode_extref(trans, root, name,
 365                                                         inode_objectid,
 366                                                         ref_objectid, index);
 367         }
 368
 369         return ret;
 370 }
 371
 372 int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
 373                              struct btrfs_root *root,
 374                              struct btrfs_path *path, u64 objectid)
 375 {
 376         struct btrfs_key key;
 377         int ret;
 378         key.objectid = objectid;
 379         key.type = BTRFS_INODE_ITEM_KEY;
 380         key.offset = 0;
 381
 382         ret = btrfs_insert_empty_item(trans, root, path, &key,
 383                                       sizeof(struct btrfs_inode_item));
 384         return ret;
 385 }
 386
 387 int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
 388                        *root, struct btrfs_path *path,
 389                        struct btrfs_key *location, int mod)
 390 {
 391         int ins_len = mod < 0 ? -1 : 0;
 392         int cow = mod != 0;
 393         int ret;
 394         int slot;
 395         struct extent_buffer *leaf;
 396         struct btrfs_key found_key;
 397
 398         ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
 399         if (ret > 0 && location->type == BTRFS_ROOT_ITEM_KEY &&
 400             location->offset == (u64)-1 && path->slots[0] != 0) {
 401                 slot = path->slots[0] - 1;
 402                 leaf = path->nodes[0];
 403                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 404                 if (found_key.objectid == location->objectid &&
 405                     found_key.type == location->type) {
 406                         path->slots[0]--;
 407                         return 0;
 408                 }
 409         }
 410         return ret;
 411 }
 412
 413 static inline void btrfs_trace_truncate(const struct btrfs_inode *inode,
 414                                         const struct extent_buffer *leaf,
 415                                         const struct btrfs_file_extent_item *fi,
 416                                         u64 offset, int extent_type, int slot)
 417 {
 418         if (!inode)
 419                 return;
 420         if (extent_type == BTRFS_FILE_EXTENT_INLINE)
 421                 trace_btrfs_truncate_show_fi_inline(inode, leaf, fi, slot,
 422                                                     offset);
 423         else
 424                 trace_btrfs_truncate_show_fi_regular(inode, leaf, fi, offset);
 425 }
 426
 427 /*
 428  * Remove inode items from a given root.
 429  *
 430  * @trans:              A transaction handle.
 431  * @root:               The root from which to remove items.
 432  * @inode:              The inode whose items we want to remove.
 433  * @control:            The btrfs_truncate_control to control how and what we
 434  *                      are truncating.
 435  *
 436  * Remove all keys associated with the inode from the given root that have a key
 437  * with a type greater than or equals to @min_type. When @min_type has a value of
 438  * BTRFS_EXTENT_DATA_KEY, only remove file extent items that have an offset value
 439  * greater than or equals to @new_size. If a file extent item that starts before
 440  * @new_size and ends after it is found, its length is adjusted.
 441  *
 442  * Returns: 0 on success, < 0 on error and NEED_TRUNCATE_BLOCK when @min_type is
 443  * BTRFS_EXTENT_DATA_KEY and the caller must truncate the last block.
 444  */
 445 int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 446                                struct btrfs_root *root,
 447                                struct btrfs_truncate_control *control)
 448 {
 449         struct btrfs_fs_info *fs_info = root->fs_info;
 450         struct btrfs_path *path;
 451         struct extent_buffer *leaf;
 452         struct btrfs_file_extent_item *fi;
 453         struct btrfs_key key;
 454         struct btrfs_key found_key;
 455         u64 new_size = control->new_size;
 456         u64 extent_num_bytes = 0;
 457         u64 extent_offset = 0;
 458         u64 item_end = 0;
 459         u32 found_type = (u8)-1;
 460         int del_item;
 461         int pending_del_nr = 0;
 462         int pending_del_slot = 0;
 463         int extent_type = -1;
 464         int ret;
 465         u64 bytes_deleted = 0;
 466         bool be_nice = false;
 467
 468         ASSERT(control->inode || !control->clear_extent_range);
 469         ASSERT(new_size == 0 || control->min_type == BTRFS_EXTENT_DATA_KEY);
 470
 471         control->last_size = new_size;
 472         control->sub_bytes = 0;
 473
 474         /*
 475          * For shareable roots we want to back off from time to time, this turns
 476          * out to be subvolume roots, reloc roots, and data reloc roots.
 477          */
 478         if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
 479                 be_nice = true;
 480
 481         path = btrfs_alloc_path();
 482         if (!path)
 483                 return -ENOMEM;
 484         path->reada = READA_BACK;
 485
 486         key.objectid = control->ino;
 487         key.type = (u8)-1;
 488         key.offset = (u64)-1;
 489
 490 search_again:
 491         /*
 492          * With a 16K leaf size and 128MiB extents, you can actually queue up a
 493          * huge file in a single leaf.  Most of the time that bytes_deleted is
 494          * > 0, it will be huge by the time we get here
 495          */
 496         if (be_nice && bytes_deleted > SZ_32M &&
 497             btrfs_should_end_transaction(trans)) {
 498                 ret = -EAGAIN;
 499                 goto out;
 500         }
 501
 502         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 503         if (ret < 0)
 504                 goto out;
 505
 506         if (ret > 0) {
 507                 ret = 0;
 508                 /* There are no items in the tree for us to truncate, we're done */
 509                 if (path->slots[0] == 0)
 510                         goto out;
 511                 path->slots[0]--;
 512         }
 513
 514         while (1) {
 515                 u64 clear_start = 0, clear_len = 0, extent_start = 0;
 516                 bool refill_delayed_refs_rsv = false;
 517
 518                 fi = NULL;
 519                 leaf = path->nodes[0];
 520                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 521                 found_type = found_key.type;
 522
 523                 if (found_key.objectid != control->ino)
 524                         break;
 525
 526                 if (found_type < control->min_type)
 527                         break;
 528
 529                 item_end = found_key.offset;
 530                 if (found_type == BTRFS_EXTENT_DATA_KEY) {
 531                         fi = btrfs_item_ptr(leaf, path->slots[0],
 532                                             struct btrfs_file_extent_item);
 533                         extent_type = btrfs_file_extent_type(leaf, fi);
 534                         if (extent_type != BTRFS_FILE_EXTENT_INLINE)
 535                                 item_end +=
 536                                     btrfs_file_extent_num_bytes(leaf, fi);
 537                         else if (extent_type == BTRFS_FILE_EXTENT_INLINE)
 538                                 item_end += btrfs_file_extent_ram_bytes(leaf, fi);
 539
 540                         btrfs_trace_truncate(control->inode, leaf, fi,
 541                                              found_key.offset, extent_type,
 542                                              path->slots[0]);
 543                         item_end--;
 544                 }
 545                 if (found_type > control->min_type) {
 546                         del_item = 1;
 547                 } else {
 548                         if (item_end < new_size)
 549                                 break;
 550                         if (found_key.offset >= new_size)
 551                                 del_item = 1;
 552                         else
 553                                 del_item = 0;
 554                 }
 555
 556                 /* FIXME, shrink the extent if the ref count is only 1 */
 557                 if (found_type != BTRFS_EXTENT_DATA_KEY)
 558                         goto delete;
 559
 560                 control->extents_found++;
 561
 562                 if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
 563                         u64 num_dec;
 564
 565                         clear_start = found_key.offset;
 566                         extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
 567                         if (!del_item) {
 568                                 u64 orig_num_bytes =
 569                                         btrfs_file_extent_num_bytes(leaf, fi);
 570                                 extent_num_bytes = ALIGN(new_size -
 571                                                 found_key.offset,
 572                                                 fs_info->sectorsize);
 573                                 clear_start = ALIGN(new_size, fs_info->sectorsize);
 574
 575                                 btrfs_set_file_extent_num_bytes(leaf, fi,
 576                                                          extent_num_bytes);
 577                                 num_dec = (orig_num_bytes - extent_num_bytes);
 578                                 if (extent_start != 0)
 579                                         control->sub_bytes += num_dec;
 580                         } else {
 581                                 extent_num_bytes =
 582                                         btrfs_file_extent_disk_num_bytes(leaf, fi);
 583                                 extent_offset = found_key.offset -
 584                                         btrfs_file_extent_offset(leaf, fi);
 585
 586                                 /* FIXME blocksize != 4096 */
 587                                 num_dec = btrfs_file_extent_num_bytes(leaf, fi);
 588                                 if (extent_start != 0)
 589                                         control->sub_bytes += num_dec;
 590                         }
 591                         clear_len = num_dec;
 592                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 593                         /*
 594                          * We can't truncate inline items that have had
 595                          * special encodings
 596                          */
 597                         if (!del_item &&
 598                             btrfs_file_extent_encryption(leaf, fi) == 0 &&
 599                             btrfs_file_extent_other_encoding(leaf, fi) == 0 &&
 600                             btrfs_file_extent_compression(leaf, fi) == 0) {
 601                                 u32 size = (u32)(new_size - found_key.offset);
 602
 603                                 btrfs_set_file_extent_ram_bytes(leaf, fi, size);
 604                                 size = btrfs_file_extent_calc_inline_size(size);
 605                                 btrfs_truncate_item(trans, path, size, 1);
 606                         } else if (!del_item) {
 607                                 /*
 608                                  * We have to bail so the last_size is set to
 609                                  * just before this extent.
 610                                  */
 611                                 ret = BTRFS_NEED_TRUNCATE_BLOCK;
 612                                 break;
 613                         } else {
 614                                 /*
 615                                  * Inline extents are special, we just treat
 616                                  * them as a full sector worth in the file
 617                                  * extent tree just for simplicity sake.
 618                                  */
 619                                 clear_len = fs_info->sectorsize;
 620                         }
 621
 622                         control->sub_bytes += item_end + 1 - new_size;
 623                 }
 624 delete:
 625                 /*
 626                  * We only want to clear the file extent range if we're
 627                  * modifying the actual inode's mapping, which is just the
 628                  * normal truncate path.
 629                  */
 630                 if (control->clear_extent_range) {
 631                         ret = btrfs_inode_clear_file_extent_range(control->inode,
 632                                                   clear_start, clear_len);
 633                         if (ret) {
 634                                 btrfs_abort_transaction(trans, ret);
 635                                 break;
 636                         }
 637                 }
 638
 639                 if (del_item) {
 640                         ASSERT(!pending_del_nr ||
 641                                ((path->slots[0] + 1) == pending_del_slot));
 642
 643                         control->last_size = found_key.offset;
 644                         if (!pending_del_nr) {
 645                                 /* No pending yet, add ourselves */
 646                                 pending_del_slot = path->slots[0];
 647                                 pending_del_nr = 1;
 648                         } else if (path->slots[0] + 1 == pending_del_slot) {
 649                                 /* Hop on the pending chunk */
 650                                 pending_del_nr++;
 651                                 pending_del_slot = path->slots[0];
 652                         }
 653                 } else {
 654                         control->last_size = new_size;
 655                         break;
 656                 }
 657
 658                 if (del_item && extent_start != 0 && !control->skip_ref_updates) {
 659                         struct btrfs_ref ref = {
 660                                 .action = BTRFS_DROP_DELAYED_REF,
 661                                 .bytenr = extent_start,
 662                                 .num_bytes = extent_num_bytes,
 663                                 .owning_root = btrfs_root_id(root),
 664                                 .ref_root = btrfs_header_owner(leaf),
 665                         };
 666
 667                         bytes_deleted += extent_num_bytes;
 668
 669                         btrfs_init_data_ref(&ref, control->ino, extent_offset,
 670                                             btrfs_root_id(root), false);
 671                         ret = btrfs_free_extent(trans, &ref);
 672                         if (ret) {
 673                                 btrfs_abort_transaction(trans, ret);
 674                                 break;
 675                         }
 676                         if (be_nice && btrfs_check_space_for_delayed_refs(fs_info))
 677                                 refill_delayed_refs_rsv = true;
 678                 }
 679
 680                 if (found_type == BTRFS_INODE_ITEM_KEY)
 681                         break;
 682
 683                 if (path->slots[0] == 0 ||
 684                     path->slots[0] != pending_del_slot ||
 685                     refill_delayed_refs_rsv) {
 686                         if (pending_del_nr) {
 687                                 ret = btrfs_del_items(trans, root, path,
 688                                                 pending_del_slot,
 689                                                 pending_del_nr);
 690                                 if (ret) {
 691                                         btrfs_abort_transaction(trans, ret);
 692                                         break;
 693                                 }
 694                                 pending_del_nr = 0;
 695                         }
 696                         btrfs_release_path(path);
 697
 698                         /*
 699                          * We can generate a lot of delayed refs, so we need to
 700                          * throttle every once and a while and make sure we're
 701                          * adding enough space to keep up with the work we are
 702                          * generating.  Since we hold a transaction here we
 703                          * can't flush, and we don't want to FLUSH_LIMIT because
 704                          * we could have generated too many delayed refs to
 705                          * actually allocate, so just bail if we're short and
 706                          * let the normal reservation dance happen higher up.
 707                          */
 708                         if (refill_delayed_refs_rsv) {
 709                                 ret = btrfs_delayed_refs_rsv_refill(fs_info,
 710                                                         BTRFS_RESERVE_NO_FLUSH);
 711                                 if (ret) {
 712                                         ret = -EAGAIN;
 713                                         break;
 714                                 }
 715                         }
 716                         goto search_again;
 717                 } else {
 718                         path->slots[0]--;
 719                 }
 720         }
 721 out:
 722         if (ret >= 0 && pending_del_nr) {
 723                 int err;
 724
 725                 err = btrfs_del_items(trans, root, path, pending_del_slot,
 726                                       pending_del_nr);
 727                 if (err) {
 728                         btrfs_abort_transaction(trans, err);
 729                         ret = err;
 730                 }
 731         }
 732
 733         ASSERT(control->last_size >= new_size);
 734         if (!ret && control->last_size > new_size)
 735                 control->last_size = new_size;
 736
 737         btrfs_free_path(path);
 738         return ret;
 739 }