1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext4/indirect.c 4 * 5 * from 6 * 7 * linux/fs/ext4/inode.c 8 * 9 * Copyright (C) 1992, 1993, 1994, 1995 10 * Remy Card (card@masi.ibp.fr) 11 * Laboratoire MASI - Institut Blaise Pascal 12 * Universite Pierre et Marie Curie (Paris VI) 13 * 14 * from 15 * 16 * linux/fs/minix/inode.c 17 * 18 * Copyright (C) 1991, 1992 Linus Torvalds 19 * 20 * Goal-directed block allocation by Stephen Tweedie 21 * (sct@redhat.com), 1993, 1998 22 */ 23 24 #include "ext4_jbd2.h" 25 #include "truncate.h" 26 #include <linux/dax.h> 27 #include <linux/uio.h> 28 29 #include <trace/events/ext4.h> 30 31 typedef struct { 32 __le32 *p; 33 __le32 key; 34 struct buffer_head *bh; 35 } Indirect; 36 37 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v) 38 { 39 p->key = *(p->p = v); 40 p->bh = bh; 41 } 42 43 /** 44 * ext4_block_to_path - parse the block number into array of offsets 45 * @inode: inode in question (we are only interested in its superblock) 46 * @i_block: block number to be parsed 47 * @offsets: array to store the offsets in 48 * @boundary: set this non-zero if the referred-to block is likely to be 49 * followed (on disk) by an indirect block. 50 * 51 * To store the locations of file's data ext4 uses a data structure common 52 * for UNIX filesystems - tree of pointers anchored in the inode, with 53 * data blocks at leaves and indirect blocks in intermediate nodes. 54 * This function translates the block number into path in that tree - 55 * return value is the path length and @offsets[n] is the offset of 56 * pointer to (n+1)th node in the nth one. If @block is out of range 57 * (negative or too large) warning is printed and zero returned. 58 * 59 * Note: function doesn't find node addresses, so no IO is needed. All 60 * we need to know is the capacity of indirect blocks (taken from the 61 * inode->i_sb). 62 */ 63 64 /* 65 * Portability note: the last comparison (check that we fit into triple 66 * indirect block) is spelled differently, because otherwise on an 67 * architecture with 32-bit longs and 8Kb pages we might get into trouble 68 * if our filesystem had 8Kb blocks. We might use long long, but that would 69 * kill us on x86. Oh, well, at least the sign propagation does not matter - 70 * i_block would have to be negative in the very beginning, so we would not 71 * get there at all. 72 */ 73 74 static int ext4_block_to_path(struct inode *inode, 75 ext4_lblk_t i_block, 76 ext4_lblk_t offsets[4], int *boundary) 77 { 78 int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb); 79 int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb); 80 const long direct_blocks = EXT4_NDIR_BLOCKS, 81 indirect_blocks = ptrs, 82 double_blocks = (1 << (ptrs_bits * 2)); 83 int n = 0; 84 int final = 0; 85 86 if (i_block < direct_blocks) { 87 offsets[n++] = i_block; 88 final = direct_blocks; 89 } else if ((i_block -= direct_blocks) < indirect_blocks) { 90 offsets[n++] = EXT4_IND_BLOCK; 91 offsets[n++] = i_block; 92 final = ptrs; 93 } else if ((i_block -= indirect_blocks) < double_blocks) { 94 offsets[n++] = EXT4_DIND_BLOCK; 95 offsets[n++] = i_block >> ptrs_bits; 96 offsets[n++] = i_block & (ptrs - 1); 97 final = ptrs; 98 } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) { 99 offsets[n++] = EXT4_TIND_BLOCK; 100 offsets[n++] = i_block >> (ptrs_bits * 2); 101 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1); 102 offsets[n++] = i_block & (ptrs - 1); 103 final = ptrs; 104 } else { 105 ext4_warning(inode->i_sb, "block %lu > max in inode %lu", 106 i_block + direct_blocks + 107 indirect_blocks + double_blocks, inode->i_ino); 108 } 109 if (boundary) 110 *boundary = final - 1 - (i_block & (ptrs - 1)); 111 return n; 112 } 113 114 /** 115 * ext4_get_branch - read the chain of indirect blocks leading to data 116 * @inode: inode in question 117 * @depth: depth of the chain (1 - direct pointer, etc.) 118 * @offsets: offsets of pointers in inode/indirect blocks 119 * @chain: place to store the result 120 * @err: here we store the error value 121 * 122 * Function fills the array of triples <key, p, bh> and returns %NULL 123 * if everything went OK or the pointer to the last filled triple 124 * (incomplete one) otherwise. Upon the return chain[i].key contains 125 * the number of (i+1)-th block in the chain (as it is stored in memory, 126 * i.e. little-endian 32-bit), chain[i].p contains the address of that 127 * number (it points into struct inode for i==0 and into the bh->b_data 128 * for i>0) and chain[i].bh points to the buffer_head of i-th indirect 129 * block for i>0 and NULL for i==0. In other words, it holds the block 130 * numbers of the chain, addresses they were taken from (and where we can 131 * verify that chain did not change) and buffer_heads hosting these 132 * numbers. 133 * 134 * Function stops when it stumbles upon zero pointer (absent block) 135 * (pointer to last triple returned, *@err == 0) 136 * or when it gets an IO error reading an indirect block 137 * (ditto, *@err == -EIO) 138 * or when it reads all @depth-1 indirect blocks successfully and finds 139 * the whole chain, all way to the data (returns %NULL, *err == 0). 140 * 141 * Need to be called with 142 * down_read(&EXT4_I(inode)->i_data_sem) 143 */ 144 static Indirect *ext4_get_branch(struct inode *inode, int depth, 145 ext4_lblk_t *offsets, 146 Indirect chain[4], int *err) 147 { 148 struct super_block *sb = inode->i_sb; 149 Indirect *p = chain; 150 struct buffer_head *bh; 151 unsigned int key; 152 int ret = -EIO; 153 154 *err = 0; 155 /* i_data is not going away, no lock needed */ 156 add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets); 157 if (!p->key) 158 goto no_block; 159 while (--depth) { 160 key = le32_to_cpu(p->key); 161 if (key > ext4_blocks_count(EXT4_SB(sb)->s_es)) { 162 /* the block was out of range */ 163 ret = -EFSCORRUPTED; 164 goto failure; 165 } 166 bh = sb_getblk(sb, key); 167 if (unlikely(!bh)) { 168 ret = -ENOMEM; 169 goto failure; 170 } 171 172 if (!bh_uptodate_or_lock(bh)) { 173 if (ext4_read_bh(bh, 0, NULL) < 0) { 174 put_bh(bh); 175 goto failure; 176 } 177 /* validate block references */ 178 if (ext4_check_indirect_blockref(inode, bh)) { 179 put_bh(bh); 180 goto failure; 181 } 182 } 183 184 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets); 185 /* Reader: end */ 186 if (!p->key) 187 goto no_block; 188 } 189 return NULL; 190 191 failure: 192 *err = ret; 193 no_block: 194 return p; 195 } 196 197 /** 198 * ext4_find_near - find a place for allocation with sufficient locality 199 * @inode: owner 200 * @ind: descriptor of indirect block. 201 * 202 * This function returns the preferred place for block allocation. 203 * It is used when heuristic for sequential allocation fails. 204 * Rules are: 205 * + if there is a block to the left of our position - allocate near it. 206 * + if pointer will live in indirect block - allocate near that block. 207 * + if pointer will live in inode - allocate in the same 208 * cylinder group. 209 * 210 * In the latter case we colour the starting block by the callers PID to 211 * prevent it from clashing with concurrent allocations for a different inode 212 * in the same block group. The PID is used here so that functionally related 213 * files will be close-by on-disk. 214 * 215 * Caller must make sure that @ind is valid and will stay that way. 216 */ 217 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind) 218 { 219 struct ext4_inode_info *ei = EXT4_I(inode); 220 __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data; 221 __le32 *p; 222 223 /* Try to find previous block */ 224 for (p = ind->p - 1; p >= start; p--) { 225 if (*p) 226 return le32_to_cpu(*p); 227 } 228 229 /* No such thing, so let's try location of indirect block */ 230 if (ind->bh) 231 return ind->bh->b_blocknr; 232 233 /* 234 * It is going to be referred to from the inode itself? OK, just put it 235 * into the same cylinder group then. 236 */ 237 return ext4_inode_to_goal_block(inode); 238 } 239 240 /** 241 * ext4_find_goal - find a preferred place for allocation. 242 * @inode: owner 243 * @block: block we want 244 * @partial: pointer to the last triple within a chain 245 * 246 * Normally this function find the preferred place for block allocation, 247 * returns it. 248 * Because this is only used for non-extent files, we limit the block nr 249 * to 32 bits. 250 */ 251 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block, 252 Indirect *partial) 253 { 254 ext4_fsblk_t goal; 255 256 /* 257 * XXX need to get goal block from mballoc's data structures 258 */ 259 260 goal = ext4_find_near(inode, partial); 261 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS; 262 return goal; 263 } 264 265 /** 266 * ext4_blks_to_allocate - Look up the block map and count the number 267 * of direct blocks need to be allocated for the given branch. 268 * 269 * @branch: chain of indirect blocks 270 * @k: number of blocks need for indirect blocks 271 * @blks: number of data blocks to be mapped. 272 * @blocks_to_boundary: the offset in the indirect block 273 * 274 * return the total number of blocks to be allocate, including the 275 * direct and indirect blocks. 276 */ 277 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks, 278 int blocks_to_boundary) 279 { 280 unsigned int count = 0; 281 282 /* 283 * Simple case, [t,d]Indirect block(s) has not allocated yet 284 * then it's clear blocks on that path have not allocated 285 */ 286 if (k > 0) { 287 /* right now we don't handle cross boundary allocation */ 288 if (blks < blocks_to_boundary + 1) 289 count += blks; 290 else 291 count += blocks_to_boundary + 1; 292 return count; 293 } 294 295 count++; 296 while (count < blks && count <= blocks_to_boundary && 297 le32_to_cpu(*(branch[0].p + count)) == 0) { 298 count++; 299 } 300 return count; 301 } 302 303 /** 304 * ext4_alloc_branch() - allocate and set up a chain of blocks 305 * @handle: handle for this transaction 306 * @ar: structure describing the allocation request 307 * @indirect_blks: number of allocated indirect blocks 308 * @offsets: offsets (in the blocks) to store the pointers to next. 309 * @branch: place to store the chain in. 310 * 311 * This function allocates blocks, zeroes out all but the last one, 312 * links them into chain and (if we are synchronous) writes them to disk. 313 * In other words, it prepares a branch that can be spliced onto the 314 * inode. It stores the information about that chain in the branch[], in 315 * the same format as ext4_get_branch() would do. We are calling it after 316 * we had read the existing part of chain and partial points to the last 317 * triple of that (one with zero ->key). Upon the exit we have the same 318 * picture as after the successful ext4_get_block(), except that in one 319 * place chain is disconnected - *branch->p is still zero (we did not 320 * set the last link), but branch->key contains the number that should 321 * be placed into *branch->p to fill that gap. 322 * 323 * If allocation fails we free all blocks we've allocated (and forget 324 * their buffer_heads) and return the error value the from failed 325 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain 326 * as described above and return 0. 327 */ 328 static int ext4_alloc_branch(handle_t *handle, 329 struct ext4_allocation_request *ar, 330 int indirect_blks, ext4_lblk_t *offsets, 331 Indirect *branch) 332 { 333 struct buffer_head * bh; 334 ext4_fsblk_t b, new_blocks[4]; 335 __le32 *p; 336 int i, j, err, len = 1; 337 338 for (i = 0; i <= indirect_blks; i++) { 339 if (i == indirect_blks) { 340 new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err); 341 } else { 342 ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle, 343 ar->inode, ar->goal, 344 ar->flags & EXT4_MB_DELALLOC_RESERVED, 345 NULL, &err); 346 /* Simplify error cleanup... */ 347 branch[i+1].bh = NULL; 348 } 349 if (err) { 350 i--; 351 goto failed; 352 } 353 branch[i].key = cpu_to_le32(new_blocks[i]); 354 if (i == 0) 355 continue; 356 357 bh = branch[i].bh = sb_getblk(ar->inode->i_sb, new_blocks[i-1]); 358 if (unlikely(!bh)) { 359 err = -ENOMEM; 360 goto failed; 361 } 362 lock_buffer(bh); 363 BUFFER_TRACE(bh, "call get_create_access"); 364 err = ext4_journal_get_create_access(handle, ar->inode->i_sb, 365 bh, EXT4_JTR_NONE); 366 if (err) { 367 unlock_buffer(bh); 368 goto failed; 369 } 370 371 memset(bh->b_data, 0, bh->b_size); 372 p = branch[i].p = (__le32 *) bh->b_data + offsets[i]; 373 b = new_blocks[i]; 374 375 if (i == indirect_blks) 376 len = ar->len; 377 for (j = 0; j < len; j++) 378 *p++ = cpu_to_le32(b++); 379 380 BUFFER_TRACE(bh, "marking uptodate"); 381 set_buffer_uptodate(bh); 382 unlock_buffer(bh); 383 384 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata"); 385 err = ext4_handle_dirty_metadata(handle, ar->inode, bh); 386 if (err) 387 goto failed; 388 } 389 return 0; 390 failed: 391 if (i == indirect_blks) { 392 /* Free data blocks */ 393 ext4_free_blocks(handle, ar->inode, NULL, new_blocks[i], 394 ar->len, 0); 395 i--; 396 } 397 for (; i >= 0; i--) { 398 /* 399 * We want to ext4_forget() only freshly allocated indirect 400 * blocks. Buffer for new_blocks[i] is at branch[i+1].bh 401 * (buffer at branch[0].bh is indirect block / inode already 402 * existing before ext4_alloc_branch() was called). Also 403 * because blocks are freshly allocated, we don't need to 404 * revoke them which is why we don't set 405 * EXT4_FREE_BLOCKS_METADATA. 406 */ 407 ext4_free_blocks(handle, ar->inode, branch[i+1].bh, 408 new_blocks[i], 1, 409 branch[i+1].bh ? EXT4_FREE_BLOCKS_FORGET : 0); 410 } 411 return err; 412 } 413 414 /** 415 * ext4_splice_branch() - splice the allocated branch onto inode. 416 * @handle: handle for this transaction 417 * @ar: structure describing the allocation request 418 * @where: location of missing link 419 * @num: number of indirect blocks we are adding 420 * 421 * This function fills the missing link and does all housekeeping needed in 422 * inode (->i_blocks, etc.). In case of success we end up with the full 423 * chain to new block and return 0. 424 */ 425 static int ext4_splice_branch(handle_t *handle, 426 struct ext4_allocation_request *ar, 427 Indirect *where, int num) 428 { 429 int i; 430 int err = 0; 431 ext4_fsblk_t current_block; 432 433 /* 434 * If we're splicing into a [td]indirect block (as opposed to the 435 * inode) then we need to get write access to the [td]indirect block 436 * before the splice. 437 */ 438 if (where->bh) { 439 BUFFER_TRACE(where->bh, "get_write_access"); 440 err = ext4_journal_get_write_access(handle, ar->inode->i_sb, 441 where->bh, EXT4_JTR_NONE); 442 if (err) 443 goto err_out; 444 } 445 /* That's it */ 446 447 *where->p = where->key; 448 449 /* 450 * Update the host buffer_head or inode to point to more just allocated 451 * direct blocks blocks 452 */ 453 if (num == 0 && ar->len > 1) { 454 current_block = le32_to_cpu(where->key) + 1; 455 for (i = 1; i < ar->len; i++) 456 *(where->p + i) = cpu_to_le32(current_block++); 457 } 458 459 /* We are done with atomic stuff, now do the rest of housekeeping */ 460 /* had we spliced it onto indirect block? */ 461 if (where->bh) { 462 /* 463 * If we spliced it onto an indirect block, we haven't 464 * altered the inode. Note however that if it is being spliced 465 * onto an indirect block at the very end of the file (the 466 * file is growing) then we *will* alter the inode to reflect 467 * the new i_size. But that is not done here - it is done in 468 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode. 469 */ 470 ext4_debug("splicing indirect only\n"); 471 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata"); 472 err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh); 473 if (err) 474 goto err_out; 475 } else { 476 /* 477 * OK, we spliced it into the inode itself on a direct block. 478 */ 479 err = ext4_mark_inode_dirty(handle, ar->inode); 480 if (unlikely(err)) 481 goto err_out; 482 ext4_debug("splicing direct\n"); 483 } 484 return err; 485 486 err_out: 487 for (i = 1; i <= num; i++) { 488 /* 489 * branch[i].bh is newly allocated, so there is no 490 * need to revoke the block, which is why we don't 491 * need to set EXT4_FREE_BLOCKS_METADATA. 492 */ 493 ext4_free_blocks(handle, ar->inode, where[i].bh, 0, 1, 494 EXT4_FREE_BLOCKS_FORGET); 495 } 496 ext4_free_blocks(handle, ar->inode, NULL, le32_to_cpu(where[num].key), 497 ar->len, 0); 498 499 return err; 500 } 501 502 /* 503 * The ext4_ind_map_blocks() function handles non-extents inodes 504 * (i.e., using the traditional indirect/double-indirect i_blocks 505 * scheme) for ext4_map_blocks(). 506 * 507 * Allocation strategy is simple: if we have to allocate something, we will 508 * have to go the whole way to leaf. So let's do it before attaching anything 509 * to tree, set linkage between the newborn blocks, write them if sync is 510 * required, recheck the path, free and repeat if check fails, otherwise 511 * set the last missing link (that will protect us from any truncate-generated 512 * removals - all blocks on the path are immune now) and possibly force the 513 * write on the parent block. 514 * That has a nice additional property: no special recovery from the failed 515 * allocations is needed - we simply release blocks and do not touch anything 516 * reachable from inode. 517 * 518 * `handle' can be NULL if create == 0. 519 * 520 * return > 0, # of blocks mapped or allocated. 521 * return = 0, if plain lookup failed. 522 * return < 0, error case. 523 * 524 * The ext4_ind_get_blocks() function should be called with 525 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem 526 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or 527 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system 528 * blocks. 529 */ 530 int ext4_ind_map_blocks(handle_t *handle, struct inode *inode, 531 struct ext4_map_blocks *map, 532 int flags) 533 { 534 struct ext4_allocation_request ar; 535 int err = -EIO; 536 ext4_lblk_t offsets[4]; 537 Indirect chain[4]; 538 Indirect *partial; 539 int indirect_blks; 540 int blocks_to_boundary = 0; 541 int depth; 542 int count = 0; 543 ext4_fsblk_t first_block = 0; 544 545 trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags); 546 ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))); 547 ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0); 548 depth = ext4_block_to_path(inode, map->m_lblk, offsets, 549 &blocks_to_boundary); 550 551 if (depth == 0) 552 goto out; 553 554 partial = ext4_get_branch(inode, depth, offsets, chain, &err); 555 556 /* Simplest case - block found, no allocation needed */ 557 if (!partial) { 558 first_block = le32_to_cpu(chain[depth - 1].key); 559 count++; 560 /*map more blocks*/ 561 while (count < map->m_len && count <= blocks_to_boundary) { 562 ext4_fsblk_t blk; 563 564 blk = le32_to_cpu(*(chain[depth-1].p + count)); 565 566 if (blk == first_block + count) 567 count++; 568 else 569 break; 570 } 571 goto got_it; 572 } 573 574 /* Next simple case - plain lookup failed */ 575 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) { 576 unsigned epb = inode->i_sb->s_blocksize / sizeof(u32); 577 int i; 578 579 /* 580 * Count number blocks in a subtree under 'partial'. At each 581 * level we count number of complete empty subtrees beyond 582 * current offset and then descend into the subtree only 583 * partially beyond current offset. 584 */ 585 count = 0; 586 for (i = partial - chain + 1; i < depth; i++) 587 count = count * epb + (epb - offsets[i] - 1); 588 count++; 589 /* Fill in size of a hole we found */ 590 map->m_pblk = 0; 591 map->m_len = min_t(unsigned int, map->m_len, count); 592 goto cleanup; 593 } 594 595 /* Failed read of indirect block */ 596 if (err == -EIO) 597 goto cleanup; 598 599 /* 600 * Okay, we need to do block allocation. 601 */ 602 if (ext4_has_feature_bigalloc(inode->i_sb)) { 603 EXT4_ERROR_INODE(inode, "Can't allocate blocks for " 604 "non-extent mapped inodes with bigalloc"); 605 err = -EFSCORRUPTED; 606 goto out; 607 } 608 609 /* Set up for the direct block allocation */ 610 memset(&ar, 0, sizeof(ar)); 611 ar.inode = inode; 612 ar.logical = map->m_lblk; 613 if (S_ISREG(inode->i_mode)) 614 ar.flags = EXT4_MB_HINT_DATA; 615 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) 616 ar.flags |= EXT4_MB_DELALLOC_RESERVED; 617 if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL) 618 ar.flags |= EXT4_MB_USE_RESERVED; 619 620 ar.goal = ext4_find_goal(inode, map->m_lblk, partial); 621 622 /* the number of blocks need to allocate for [d,t]indirect blocks */ 623 indirect_blks = (chain + depth) - partial - 1; 624 625 /* 626 * Next look up the indirect map to count the totoal number of 627 * direct blocks to allocate for this branch. 628 */ 629 ar.len = ext4_blks_to_allocate(partial, indirect_blks, 630 map->m_len, blocks_to_boundary); 631 632 /* 633 * Block out ext4_truncate while we alter the tree 634 */ 635 err = ext4_alloc_branch(handle, &ar, indirect_blks, 636 offsets + (partial - chain), partial); 637 638 /* 639 * The ext4_splice_branch call will free and forget any buffers 640 * on the new chain if there is a failure, but that risks using 641 * up transaction credits, especially for bitmaps where the 642 * credits cannot be returned. Can we handle this somehow? We 643 * may need to return -EAGAIN upwards in the worst case. --sct 644 */ 645 if (!err) 646 err = ext4_splice_branch(handle, &ar, partial, indirect_blks); 647 if (err) 648 goto cleanup; 649 650 map->m_flags |= EXT4_MAP_NEW; 651 652 ext4_update_inode_fsync_trans(handle, inode, 1); 653 count = ar.len; 654 655 got_it: 656 map->m_flags |= EXT4_MAP_MAPPED; 657 map->m_pblk = le32_to_cpu(chain[depth-1].key); 658 map->m_len = count; 659 if (count > blocks_to_boundary) 660 map->m_flags |= EXT4_MAP_BOUNDARY; 661 err = count; 662 /* Clean up and exit */ 663 partial = chain + depth - 1; /* the whole chain */ 664 cleanup: 665 while (partial > chain) { 666 BUFFER_TRACE(partial->bh, "call brelse"); 667 brelse(partial->bh); 668 partial--; 669 } 670 out: 671 trace_ext4_ind_map_blocks_exit(inode, flags, map, err); 672 return err; 673 } 674 675 /* 676 * Calculate number of indirect blocks touched by mapping @nrblocks logically 677 * contiguous blocks 678 */ 679 int ext4_ind_trans_blocks(struct inode *inode, int nrblocks) 680 { 681 /* 682 * With N contiguous data blocks, we need at most 683 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks, 684 * 2 dindirect blocks, and 1 tindirect block 685 */ 686 return DIV_ROUND_UP(nrblocks, EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4; 687 } 688 689 static int ext4_ind_trunc_restart_fn(handle_t *handle, struct inode *inode, 690 struct buffer_head *bh, int *dropped) 691 { 692 int err; 693 694 if (bh) { 695 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata"); 696 err = ext4_handle_dirty_metadata(handle, inode, bh); 697 if (unlikely(err)) 698 return err; 699 } 700 err = ext4_mark_inode_dirty(handle, inode); 701 if (unlikely(err)) 702 return err; 703 /* 704 * Drop i_data_sem to avoid deadlock with ext4_map_blocks. At this 705 * moment, get_block can be called only for blocks inside i_size since 706 * page cache has been already dropped and writes are blocked by 707 * i_rwsem. So we can safely drop the i_data_sem here. 708 */ 709 BUG_ON(EXT4_JOURNAL(inode) == NULL); 710 ext4_discard_preallocations(inode); 711 up_write(&EXT4_I(inode)->i_data_sem); 712 *dropped = 1; 713 return 0; 714 } 715 716 /* 717 * Truncate transactions can be complex and absolutely huge. So we need to 718 * be able to restart the transaction at a convenient checkpoint to make 719 * sure we don't overflow the journal. 720 * 721 * Try to extend this transaction for the purposes of truncation. If 722 * extend fails, we restart transaction. 723 */ 724 static int ext4_ind_truncate_ensure_credits(handle_t *handle, 725 struct inode *inode, 726 struct buffer_head *bh, 727 int revoke_creds) 728 { 729 int ret; 730 int dropped = 0; 731 732 ret = ext4_journal_ensure_credits_fn(handle, EXT4_RESERVE_TRANS_BLOCKS, 733 ext4_blocks_for_truncate(inode), revoke_creds, 734 ext4_ind_trunc_restart_fn(handle, inode, bh, &dropped)); 735 if (dropped) 736 down_write(&EXT4_I(inode)->i_data_sem); 737 if (ret <= 0) 738 return ret; 739 if (bh) { 740 BUFFER_TRACE(bh, "retaking write access"); 741 ret = ext4_journal_get_write_access(handle, inode->i_sb, bh, 742 EXT4_JTR_NONE); 743 if (unlikely(ret)) 744 return ret; 745 } 746 return 0; 747 } 748 749 /* 750 * Probably it should be a library function... search for first non-zero word 751 * or memcmp with zero_page, whatever is better for particular architecture. 752 * Linus? 753 */ 754 static inline int all_zeroes(__le32 *p, __le32 *q) 755 { 756 while (p < q) 757 if (*p++) 758 return 0; 759 return 1; 760 } 761 762 /** 763 * ext4_find_shared - find the indirect blocks for partial truncation. 764 * @inode: inode in question 765 * @depth: depth of the affected branch 766 * @offsets: offsets of pointers in that branch (see ext4_block_to_path) 767 * @chain: place to store the pointers to partial indirect blocks 768 * @top: place to the (detached) top of branch 769 * 770 * This is a helper function used by ext4_truncate(). 771 * 772 * When we do truncate() we may have to clean the ends of several 773 * indirect blocks but leave the blocks themselves alive. Block is 774 * partially truncated if some data below the new i_size is referred 775 * from it (and it is on the path to the first completely truncated 776 * data block, indeed). We have to free the top of that path along 777 * with everything to the right of the path. Since no allocation 778 * past the truncation point is possible until ext4_truncate() 779 * finishes, we may safely do the latter, but top of branch may 780 * require special attention - pageout below the truncation point 781 * might try to populate it. 782 * 783 * We atomically detach the top of branch from the tree, store the 784 * block number of its root in *@top, pointers to buffer_heads of 785 * partially truncated blocks - in @chain[].bh and pointers to 786 * their last elements that should not be removed - in 787 * @chain[].p. Return value is the pointer to last filled element 788 * of @chain. 789 * 790 * The work left to caller to do the actual freeing of subtrees: 791 * a) free the subtree starting from *@top 792 * b) free the subtrees whose roots are stored in 793 * (@chain[i].p+1 .. end of @chain[i].bh->b_data) 794 * c) free the subtrees growing from the inode past the @chain[0]. 795 * (no partially truncated stuff there). */ 796 797 static Indirect *ext4_find_shared(struct inode *inode, int depth, 798 ext4_lblk_t offsets[4], Indirect chain[4], 799 __le32 *top) 800 { 801 Indirect *partial, *p; 802 int k, err; 803 804 *top = 0; 805 /* Make k index the deepest non-null offset + 1 */ 806 for (k = depth; k > 1 && !offsets[k-1]; k--) 807 ; 808 partial = ext4_get_branch(inode, k, offsets, chain, &err); 809 /* Writer: pointers */ 810 if (!partial) 811 partial = chain + k-1; 812 /* 813 * If the branch acquired continuation since we've looked at it - 814 * fine, it should all survive and (new) top doesn't belong to us. 815 */ 816 if (!partial->key && *partial->p) 817 /* Writer: end */ 818 goto no_top; 819 for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--) 820 ; 821 /* 822 * OK, we've found the last block that must survive. The rest of our 823 * branch should be detached before unlocking. However, if that rest 824 * of branch is all ours and does not grow immediately from the inode 825 * it's easier to cheat and just decrement partial->p. 826 */ 827 if (p == chain + k - 1 && p > chain) { 828 p->p--; 829 } else { 830 *top = *p->p; 831 /* Nope, don't do this in ext4. Must leave the tree intact */ 832 #if 0 833 *p->p = 0; 834 #endif 835 } 836 /* Writer: end */ 837 838 while (partial > p) { 839 brelse(partial->bh); 840 partial--; 841 } 842 no_top: 843 return partial; 844 } 845 846 /* 847 * Zero a number of block pointers in either an inode or an indirect block. 848 * If we restart the transaction we must again get write access to the 849 * indirect block for further modification. 850 * 851 * We release `count' blocks on disk, but (last - first) may be greater 852 * than `count' because there can be holes in there. 853 * 854 * Return 0 on success, 1 on invalid block range 855 * and < 0 on fatal error. 856 */ 857 static int ext4_clear_blocks(handle_t *handle, struct inode *inode, 858 struct buffer_head *bh, 859 ext4_fsblk_t block_to_free, 860 unsigned long count, __le32 *first, 861 __le32 *last) 862 { 863 __le32 *p; 864 int flags = EXT4_FREE_BLOCKS_VALIDATED; 865 int err; 866 867 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) || 868 ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE)) 869 flags |= EXT4_FREE_BLOCKS_FORGET | EXT4_FREE_BLOCKS_METADATA; 870 else if (ext4_should_journal_data(inode)) 871 flags |= EXT4_FREE_BLOCKS_FORGET; 872 873 if (!ext4_inode_block_valid(inode, block_to_free, count)) { 874 EXT4_ERROR_INODE(inode, "attempt to clear invalid " 875 "blocks %llu len %lu", 876 (unsigned long long) block_to_free, count); 877 return 1; 878 } 879 880 err = ext4_ind_truncate_ensure_credits(handle, inode, bh, 881 ext4_free_data_revoke_credits(inode, count)); 882 if (err < 0) 883 goto out_err; 884 885 for (p = first; p < last; p++) 886 *p = 0; 887 888 ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags); 889 return 0; 890 out_err: 891 ext4_std_error(inode->i_sb, err); 892 return err; 893 } 894 895 /** 896 * ext4_free_data - free a list of data blocks 897 * @handle: handle for this transaction 898 * @inode: inode we are dealing with 899 * @this_bh: indirect buffer_head which contains *@first and *@last 900 * @first: array of block numbers 901 * @last: points immediately past the end of array 902 * 903 * We are freeing all blocks referred from that array (numbers are stored as 904 * little-endian 32-bit) and updating @inode->i_blocks appropriately. 905 * 906 * We accumulate contiguous runs of blocks to free. Conveniently, if these 907 * blocks are contiguous then releasing them at one time will only affect one 908 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't 909 * actually use a lot of journal space. 910 * 911 * @this_bh will be %NULL if @first and @last point into the inode's direct 912 * block pointers. 913 */ 914 static void ext4_free_data(handle_t *handle, struct inode *inode, 915 struct buffer_head *this_bh, 916 __le32 *first, __le32 *last) 917 { 918 ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */ 919 unsigned long count = 0; /* Number of blocks in the run */ 920 __le32 *block_to_free_p = NULL; /* Pointer into inode/ind 921 corresponding to 922 block_to_free */ 923 ext4_fsblk_t nr; /* Current block # */ 924 __le32 *p; /* Pointer into inode/ind 925 for current block */ 926 int err = 0; 927 928 if (this_bh) { /* For indirect block */ 929 BUFFER_TRACE(this_bh, "get_write_access"); 930 err = ext4_journal_get_write_access(handle, inode->i_sb, 931 this_bh, EXT4_JTR_NONE); 932 /* Important: if we can't update the indirect pointers 933 * to the blocks, we can't free them. */ 934 if (err) 935 return; 936 } 937 938 for (p = first; p < last; p++) { 939 nr = le32_to_cpu(*p); 940 if (nr) { 941 /* accumulate blocks to free if they're contiguous */ 942 if (count == 0) { 943 block_to_free = nr; 944 block_to_free_p = p; 945 count = 1; 946 } else if (nr == block_to_free + count) { 947 count++; 948 } else { 949 err = ext4_clear_blocks(handle, inode, this_bh, 950 block_to_free, count, 951 block_to_free_p, p); 952 if (err) 953 break; 954 block_to_free = nr; 955 block_to_free_p = p; 956 count = 1; 957 } 958 } 959 } 960 961 if (!err && count > 0) 962 err = ext4_clear_blocks(handle, inode, this_bh, block_to_free, 963 count, block_to_free_p, p); 964 if (err < 0) 965 /* fatal error */ 966 return; 967 968 if (this_bh) { 969 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata"); 970 971 /* 972 * The buffer head should have an attached journal head at this 973 * point. However, if the data is corrupted and an indirect 974 * block pointed to itself, it would have been detached when 975 * the block was cleared. Check for this instead of OOPSing. 976 */ 977 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh)) 978 ext4_handle_dirty_metadata(handle, inode, this_bh); 979 else 980 EXT4_ERROR_INODE(inode, 981 "circular indirect block detected at " 982 "block %llu", 983 (unsigned long long) this_bh->b_blocknr); 984 } 985 } 986 987 /** 988 * ext4_free_branches - free an array of branches 989 * @handle: JBD handle for this transaction 990 * @inode: inode we are dealing with 991 * @parent_bh: the buffer_head which contains *@first and *@last 992 * @first: array of block numbers 993 * @last: pointer immediately past the end of array 994 * @depth: depth of the branches to free 995 * 996 * We are freeing all blocks referred from these branches (numbers are 997 * stored as little-endian 32-bit) and updating @inode->i_blocks 998 * appropriately. 999 */ 1000 static void ext4_free_branches(handle_t *handle, struct inode *inode, 1001 struct buffer_head *parent_bh, 1002 __le32 *first, __le32 *last, int depth) 1003 { 1004 ext4_fsblk_t nr; 1005 __le32 *p; 1006 1007 if (ext4_handle_is_aborted(handle)) 1008 return; 1009 1010 if (depth--) { 1011 struct buffer_head *bh; 1012 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb); 1013 p = last; 1014 while (--p >= first) { 1015 nr = le32_to_cpu(*p); 1016 if (!nr) 1017 continue; /* A hole */ 1018 1019 if (!ext4_inode_block_valid(inode, nr, 1)) { 1020 EXT4_ERROR_INODE(inode, 1021 "invalid indirect mapped " 1022 "block %lu (level %d)", 1023 (unsigned long) nr, depth); 1024 break; 1025 } 1026 1027 /* Go read the buffer for the next level down */ 1028 bh = ext4_sb_bread(inode->i_sb, nr, 0); 1029 1030 /* 1031 * A read failure? Report error and clear slot 1032 * (should be rare). 1033 */ 1034 if (IS_ERR(bh)) { 1035 ext4_error_inode_block(inode, nr, -PTR_ERR(bh), 1036 "Read failure"); 1037 continue; 1038 } 1039 1040 /* This zaps the entire block. Bottom up. */ 1041 BUFFER_TRACE(bh, "free child branches"); 1042 ext4_free_branches(handle, inode, bh, 1043 (__le32 *) bh->b_data, 1044 (__le32 *) bh->b_data + addr_per_block, 1045 depth); 1046 brelse(bh); 1047 1048 /* 1049 * Everything below this pointer has been 1050 * released. Now let this top-of-subtree go. 1051 * 1052 * We want the freeing of this indirect block to be 1053 * atomic in the journal with the updating of the 1054 * bitmap block which owns it. So make some room in 1055 * the journal. 1056 * 1057 * We zero the parent pointer *after* freeing its 1058 * pointee in the bitmaps, so if extend_transaction() 1059 * for some reason fails to put the bitmap changes and 1060 * the release into the same transaction, recovery 1061 * will merely complain about releasing a free block, 1062 * rather than leaking blocks. 1063 */ 1064 if (ext4_handle_is_aborted(handle)) 1065 return; 1066 if (ext4_ind_truncate_ensure_credits(handle, inode, 1067 NULL, 1068 ext4_free_metadata_revoke_credits( 1069 inode->i_sb, 1)) < 0) 1070 return; 1071 1072 /* 1073 * The forget flag here is critical because if 1074 * we are journaling (and not doing data 1075 * journaling), we have to make sure a revoke 1076 * record is written to prevent the journal 1077 * replay from overwriting the (former) 1078 * indirect block if it gets reallocated as a 1079 * data block. This must happen in the same 1080 * transaction where the data blocks are 1081 * actually freed. 1082 */ 1083 ext4_free_blocks(handle, inode, NULL, nr, 1, 1084 EXT4_FREE_BLOCKS_METADATA| 1085 EXT4_FREE_BLOCKS_FORGET); 1086 1087 if (parent_bh) { 1088 /* 1089 * The block which we have just freed is 1090 * pointed to by an indirect block: journal it 1091 */ 1092 BUFFER_TRACE(parent_bh, "get_write_access"); 1093 if (!ext4_journal_get_write_access(handle, 1094 inode->i_sb, parent_bh, 1095 EXT4_JTR_NONE)) { 1096 *p = 0; 1097 BUFFER_TRACE(parent_bh, 1098 "call ext4_handle_dirty_metadata"); 1099 ext4_handle_dirty_metadata(handle, 1100 inode, 1101 parent_bh); 1102 } 1103 } 1104 } 1105 } else { 1106 /* We have reached the bottom of the tree. */ 1107 BUFFER_TRACE(parent_bh, "free data blocks"); 1108 ext4_free_data(handle, inode, parent_bh, first, last); 1109 } 1110 } 1111 1112 void ext4_ind_truncate(handle_t *handle, struct inode *inode) 1113 { 1114 struct ext4_inode_info *ei = EXT4_I(inode); 1115 __le32 *i_data = ei->i_data; 1116 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb); 1117 ext4_lblk_t offsets[4]; 1118 Indirect chain[4]; 1119 Indirect *partial; 1120 __le32 nr = 0; 1121 int n = 0; 1122 ext4_lblk_t last_block, max_block; 1123 unsigned blocksize = inode->i_sb->s_blocksize; 1124 1125 last_block = (inode->i_size + blocksize-1) 1126 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb); 1127 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1) 1128 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb); 1129 1130 if (last_block != max_block) { 1131 n = ext4_block_to_path(inode, last_block, offsets, NULL); 1132 if (n == 0) 1133 return; 1134 } 1135 1136 ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block); 1137 1138 /* 1139 * The orphan list entry will now protect us from any crash which 1140 * occurs before the truncate completes, so it is now safe to propagate 1141 * the new, shorter inode size (held for now in i_size) into the 1142 * on-disk inode. We do this via i_disksize, which is the value which 1143 * ext4 *really* writes onto the disk inode. 1144 */ 1145 ei->i_disksize = inode->i_size; 1146 1147 if (last_block == max_block) { 1148 /* 1149 * It is unnecessary to free any data blocks if last_block is 1150 * equal to the indirect block limit. 1151 */ 1152 return; 1153 } else if (n == 1) { /* direct blocks */ 1154 ext4_free_data(handle, inode, NULL, i_data+offsets[0], 1155 i_data + EXT4_NDIR_BLOCKS); 1156 goto do_indirects; 1157 } 1158 1159 partial = ext4_find_shared(inode, n, offsets, chain, &nr); 1160 /* Kill the top of shared branch (not detached) */ 1161 if (nr) { 1162 if (partial == chain) { 1163 /* Shared branch grows from the inode */ 1164 ext4_free_branches(handle, inode, NULL, 1165 &nr, &nr+1, (chain+n-1) - partial); 1166 *partial->p = 0; 1167 /* 1168 * We mark the inode dirty prior to restart, 1169 * and prior to stop. No need for it here. 1170 */ 1171 } else { 1172 /* Shared branch grows from an indirect block */ 1173 BUFFER_TRACE(partial->bh, "get_write_access"); 1174 ext4_free_branches(handle, inode, partial->bh, 1175 partial->p, 1176 partial->p+1, (chain+n-1) - partial); 1177 } 1178 } 1179 /* Clear the ends of indirect blocks on the shared branch */ 1180 while (partial > chain) { 1181 ext4_free_branches(handle, inode, partial->bh, partial->p + 1, 1182 (__le32*)partial->bh->b_data+addr_per_block, 1183 (chain+n-1) - partial); 1184 BUFFER_TRACE(partial->bh, "call brelse"); 1185 brelse(partial->bh); 1186 partial--; 1187 } 1188 do_indirects: 1189 /* Kill the remaining (whole) subtrees */ 1190 switch (offsets[0]) { 1191 default: 1192 nr = i_data[EXT4_IND_BLOCK]; 1193 if (nr) { 1194 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1); 1195 i_data[EXT4_IND_BLOCK] = 0; 1196 } 1197 fallthrough; 1198 case EXT4_IND_BLOCK: 1199 nr = i_data[EXT4_DIND_BLOCK]; 1200 if (nr) { 1201 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2); 1202 i_data[EXT4_DIND_BLOCK] = 0; 1203 } 1204 fallthrough; 1205 case EXT4_DIND_BLOCK: 1206 nr = i_data[EXT4_TIND_BLOCK]; 1207 if (nr) { 1208 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3); 1209 i_data[EXT4_TIND_BLOCK] = 0; 1210 } 1211 fallthrough; 1212 case EXT4_TIND_BLOCK: 1213 ; 1214 } 1215 } 1216 1217 /** 1218 * ext4_ind_remove_space - remove space from the range 1219 * @handle: JBD handle for this transaction 1220 * @inode: inode we are dealing with 1221 * @start: First block to remove 1222 * @end: One block after the last block to remove (exclusive) 1223 * 1224 * Free the blocks in the defined range (end is exclusive endpoint of 1225 * range). This is used by ext4_punch_hole(). 1226 */ 1227 int ext4_ind_remove_space(handle_t *handle, struct inode *inode, 1228 ext4_lblk_t start, ext4_lblk_t end) 1229 { 1230 struct ext4_inode_info *ei = EXT4_I(inode); 1231 __le32 *i_data = ei->i_data; 1232 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb); 1233 ext4_lblk_t offsets[4], offsets2[4]; 1234 Indirect chain[4], chain2[4]; 1235 Indirect *partial, *partial2; 1236 Indirect *p = NULL, *p2 = NULL; 1237 ext4_lblk_t max_block; 1238 __le32 nr = 0, nr2 = 0; 1239 int n = 0, n2 = 0; 1240 unsigned blocksize = inode->i_sb->s_blocksize; 1241 1242 max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1) 1243 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb); 1244 if (end >= max_block) 1245 end = max_block; 1246 if ((start >= end) || (start > max_block)) 1247 return 0; 1248 1249 n = ext4_block_to_path(inode, start, offsets, NULL); 1250 n2 = ext4_block_to_path(inode, end, offsets2, NULL); 1251 1252 BUG_ON(n > n2); 1253 1254 if ((n == 1) && (n == n2)) { 1255 /* We're punching only within direct block range */ 1256 ext4_free_data(handle, inode, NULL, i_data + offsets[0], 1257 i_data + offsets2[0]); 1258 return 0; 1259 } else if (n2 > n) { 1260 /* 1261 * Start and end are on a different levels so we're going to 1262 * free partial block at start, and partial block at end of 1263 * the range. If there are some levels in between then 1264 * do_indirects label will take care of that. 1265 */ 1266 1267 if (n == 1) { 1268 /* 1269 * Start is at the direct block level, free 1270 * everything to the end of the level. 1271 */ 1272 ext4_free_data(handle, inode, NULL, i_data + offsets[0], 1273 i_data + EXT4_NDIR_BLOCKS); 1274 goto end_range; 1275 } 1276 1277 1278 partial = p = ext4_find_shared(inode, n, offsets, chain, &nr); 1279 if (nr) { 1280 if (partial == chain) { 1281 /* Shared branch grows from the inode */ 1282 ext4_free_branches(handle, inode, NULL, 1283 &nr, &nr+1, (chain+n-1) - partial); 1284 *partial->p = 0; 1285 } else { 1286 /* Shared branch grows from an indirect block */ 1287 BUFFER_TRACE(partial->bh, "get_write_access"); 1288 ext4_free_branches(handle, inode, partial->bh, 1289 partial->p, 1290 partial->p+1, (chain+n-1) - partial); 1291 } 1292 } 1293 1294 /* 1295 * Clear the ends of indirect blocks on the shared branch 1296 * at the start of the range 1297 */ 1298 while (partial > chain) { 1299 ext4_free_branches(handle, inode, partial->bh, 1300 partial->p + 1, 1301 (__le32 *)partial->bh->b_data+addr_per_block, 1302 (chain+n-1) - partial); 1303 partial--; 1304 } 1305 1306 end_range: 1307 partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2); 1308 if (nr2) { 1309 if (partial2 == chain2) { 1310 /* 1311 * Remember, end is exclusive so here we're at 1312 * the start of the next level we're not going 1313 * to free. Everything was covered by the start 1314 * of the range. 1315 */ 1316 goto do_indirects; 1317 } 1318 } else { 1319 /* 1320 * ext4_find_shared returns Indirect structure which 1321 * points to the last element which should not be 1322 * removed by truncate. But this is end of the range 1323 * in punch_hole so we need to point to the next element 1324 */ 1325 partial2->p++; 1326 } 1327 1328 /* 1329 * Clear the ends of indirect blocks on the shared branch 1330 * at the end of the range 1331 */ 1332 while (partial2 > chain2) { 1333 ext4_free_branches(handle, inode, partial2->bh, 1334 (__le32 *)partial2->bh->b_data, 1335 partial2->p, 1336 (chain2+n2-1) - partial2); 1337 partial2--; 1338 } 1339 goto do_indirects; 1340 } 1341 1342 /* Punch happened within the same level (n == n2) */ 1343 partial = p = ext4_find_shared(inode, n, offsets, chain, &nr); 1344 partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2); 1345 1346 /* Free top, but only if partial2 isn't its subtree. */ 1347 if (nr) { 1348 int level = min(partial - chain, partial2 - chain2); 1349 int i; 1350 int subtree = 1; 1351 1352 for (i = 0; i <= level; i++) { 1353 if (offsets[i] != offsets2[i]) { 1354 subtree = 0; 1355 break; 1356 } 1357 } 1358 1359 if (!subtree) { 1360 if (partial == chain) { 1361 /* Shared branch grows from the inode */ 1362 ext4_free_branches(handle, inode, NULL, 1363 &nr, &nr+1, 1364 (chain+n-1) - partial); 1365 *partial->p = 0; 1366 } else { 1367 /* Shared branch grows from an indirect block */ 1368 BUFFER_TRACE(partial->bh, "get_write_access"); 1369 ext4_free_branches(handle, inode, partial->bh, 1370 partial->p, 1371 partial->p+1, 1372 (chain+n-1) - partial); 1373 } 1374 } 1375 } 1376 1377 if (!nr2) { 1378 /* 1379 * ext4_find_shared returns Indirect structure which 1380 * points to the last element which should not be 1381 * removed by truncate. But this is end of the range 1382 * in punch_hole so we need to point to the next element 1383 */ 1384 partial2->p++; 1385 } 1386 1387 while (partial > chain || partial2 > chain2) { 1388 int depth = (chain+n-1) - partial; 1389 int depth2 = (chain2+n2-1) - partial2; 1390 1391 if (partial > chain && partial2 > chain2 && 1392 partial->bh->b_blocknr == partial2->bh->b_blocknr) { 1393 /* 1394 * We've converged on the same block. Clear the range, 1395 * then we're done. 1396 */ 1397 ext4_free_branches(handle, inode, partial->bh, 1398 partial->p + 1, 1399 partial2->p, 1400 (chain+n-1) - partial); 1401 goto cleanup; 1402 } 1403 1404 /* 1405 * The start and end partial branches may not be at the same 1406 * level even though the punch happened within one level. So, we 1407 * give them a chance to arrive at the same level, then walk 1408 * them in step with each other until we converge on the same 1409 * block. 1410 */ 1411 if (partial > chain && depth <= depth2) { 1412 ext4_free_branches(handle, inode, partial->bh, 1413 partial->p + 1, 1414 (__le32 *)partial->bh->b_data+addr_per_block, 1415 (chain+n-1) - partial); 1416 partial--; 1417 } 1418 if (partial2 > chain2 && depth2 <= depth) { 1419 ext4_free_branches(handle, inode, partial2->bh, 1420 (__le32 *)partial2->bh->b_data, 1421 partial2->p, 1422 (chain2+n2-1) - partial2); 1423 partial2--; 1424 } 1425 } 1426 1427 cleanup: 1428 while (p && p > chain) { 1429 BUFFER_TRACE(p->bh, "call brelse"); 1430 brelse(p->bh); 1431 p--; 1432 } 1433 while (p2 && p2 > chain2) { 1434 BUFFER_TRACE(p2->bh, "call brelse"); 1435 brelse(p2->bh); 1436 p2--; 1437 } 1438 return 0; 1439 1440 do_indirects: 1441 /* Kill the remaining (whole) subtrees */ 1442 switch (offsets[0]) { 1443 default: 1444 if (++n >= n2) 1445 break; 1446 nr = i_data[EXT4_IND_BLOCK]; 1447 if (nr) { 1448 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1); 1449 i_data[EXT4_IND_BLOCK] = 0; 1450 } 1451 fallthrough; 1452 case EXT4_IND_BLOCK: 1453 if (++n >= n2) 1454 break; 1455 nr = i_data[EXT4_DIND_BLOCK]; 1456 if (nr) { 1457 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2); 1458 i_data[EXT4_DIND_BLOCK] = 0; 1459 } 1460 fallthrough; 1461 case EXT4_DIND_BLOCK: 1462 if (++n >= n2) 1463 break; 1464 nr = i_data[EXT4_TIND_BLOCK]; 1465 if (nr) { 1466 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3); 1467 i_data[EXT4_TIND_BLOCK] = 0; 1468 } 1469 fallthrough; 1470 case EXT4_TIND_BLOCK: 1471 ; 1472 } 1473 goto cleanup; 1474 } 1475