fs/ext2/inode.c

   1 /*
   2  *  linux/fs/ext2/inode.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/inode.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  Goal-directed block allocation by Stephen Tweedie
  16  *      (sct@dcs.ed.ac.uk), 1993, 1998
  17  *  Big-endian to little-endian byte-swapping/bitmaps by
  18  *        David S. Miller (davem@caip.rutgers.edu), 1995
  19  *  64-bit file support on 64-bit platforms by Jakub Jelinek
  20  *      (jj@sunsite.ms.mff.cuni.cz)
  21  *
  22  *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
  23  */
  24
  25 #include <linux/time.h>
  26 #include <linux/highuid.h>
  27 #include <linux/pagemap.h>
  28 #include <linux/dax.h>
  29 #include <linux/blkdev.h>
  30 #include <linux/quotaops.h>
  31 #include <linux/writeback.h>
  32 #include <linux/buffer_head.h>
  33 #include <linux/mpage.h>
  34 #include <linux/fiemap.h>
  35 #include <linux/iomap.h>
  36 #include <linux/namei.h>
  37 #include <linux/uio.h>
  38 #include "ext2.h"
  39 #include "acl.h"
  40 #include "xattr.h"
  41
  42 static int __ext2_write_inode(struct inode *inode, int do_sync);
  43
  44 /*
  45  * Test whether an inode is a fast symlink.
  46  */
  47 static inline int ext2_inode_is_fast_symlink(struct inode *inode)
  48 {
  49         int ea_blocks = EXT2_I(inode)->i_file_acl ?
  50                 (inode->i_sb->s_blocksize >> 9) : 0;
  51
  52         return (S_ISLNK(inode->i_mode) &&
  53                 inode->i_blocks - ea_blocks == 0);
  54 }
  55
  56 static void ext2_truncate_blocks(struct inode *inode, loff_t offset);
  57
  58 static void ext2_write_failed(struct address_space *mapping, loff_t to)
  59 {
  60         struct inode *inode = mapping->host;
  61
  62         if (to > inode->i_size) {
  63                 truncate_pagecache(inode, inode->i_size);
  64                 ext2_truncate_blocks(inode, inode->i_size);
  65         }
  66 }
  67
  68 /*
  69  * Called at the last iput() if i_nlink is zero.
  70  */
  71 void ext2_evict_inode(struct inode * inode)
  72 {
  73         struct ext2_block_alloc_info *rsv;
  74         int want_delete = 0;
  75
  76         if (!inode->i_nlink && !is_bad_inode(inode)) {
  77                 want_delete = 1;
  78                 dquot_initialize(inode);
  79         } else {
  80                 dquot_drop(inode);
  81         }
  82
  83         truncate_inode_pages_final(&inode->i_data);
  84
  85         if (want_delete) {
  86                 sb_start_intwrite(inode->i_sb);
  87                 /* set dtime */
  88                 EXT2_I(inode)->i_dtime  = get_seconds();
  89                 mark_inode_dirty(inode);
  90                 __ext2_write_inode(inode, inode_needs_sync(inode));
  91                 /* truncate to 0 */
  92                 inode->i_size = 0;
  93                 if (inode->i_blocks)
  94                         ext2_truncate_blocks(inode, 0);
  95                 ext2_xattr_delete_inode(inode);
  96         }
  97
  98         invalidate_inode_buffers(inode);
  99         clear_inode(inode);
 100
 101         ext2_discard_reservation(inode);
 102         rsv = EXT2_I(inode)->i_block_alloc_info;
 103         EXT2_I(inode)->i_block_alloc_info = NULL;
 104         if (unlikely(rsv))
 105                 kfree(rsv);
 106
 107         if (want_delete) {
 108                 ext2_free_inode(inode);
 109                 sb_end_intwrite(inode->i_sb);
 110         }
 111 }
 112
 113 typedef struct {
 114         __le32  *p;
 115         __le32  key;
 116         struct buffer_head *bh;
 117 } Indirect;
 118
 119 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
 120 {
 121         p->key = *(p->p = v);
 122         p->bh = bh;
 123 }
 124
 125 static inline int verify_chain(Indirect *from, Indirect *to)
 126 {
 127         while (from <= to && from->key == *from->p)
 128                 from++;
 129         return (from > to);
 130 }
 131
 132 /**
 133  *      ext2_block_to_path - parse the block number into array of offsets
 134  *      @inode: inode in question (we are only interested in its superblock)
 135  *      @i_block: block number to be parsed
 136  *      @offsets: array to store the offsets in
 137  *      @boundary: set this non-zero if the referred-to block is likely to be
 138  *             followed (on disk) by an indirect block.
 139  *      To store the locations of file's data ext2 uses a data structure common
 140  *      for UNIX filesystems - tree of pointers anchored in the inode, with
 141  *      data blocks at leaves and indirect blocks in intermediate nodes.
 142  *      This function translates the block number into path in that tree -
 143  *      return value is the path length and @offsets[n] is the offset of
 144  *      pointer to (n+1)th node in the nth one. If @block is out of range
 145  *      (negative or too large) warning is printed and zero returned.
 146  *
 147  *      Note: function doesn't find node addresses, so no IO is needed. All
 148  *      we need to know is the capacity of indirect blocks (taken from the
 149  *      inode->i_sb).
 150  */
 151
 152 /*
 153  * Portability note: the last comparison (check that we fit into triple
 154  * indirect block) is spelled differently, because otherwise on an
 155  * architecture with 32-bit longs and 8Kb pages we might get into trouble
 156  * if our filesystem had 8Kb blocks. We might use long long, but that would
 157  * kill us on x86. Oh, well, at least the sign propagation does not matter -
 158  * i_block would have to be negative in the very beginning, so we would not
 159  * get there at all.
 160  */
 161
 162 static int ext2_block_to_path(struct inode *inode,
 163                         long i_block, int offsets[4], int *boundary)
 164 {
 165         int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
 166         int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
 167         const long direct_blocks = EXT2_NDIR_BLOCKS,
 168                 indirect_blocks = ptrs,
 169                 double_blocks = (1 << (ptrs_bits * 2));
 170         int n = 0;
 171         int final = 0;
 172
 173         if (i_block < 0) {
 174                 ext2_msg(inode->i_sb, KERN_WARNING,
 175                         "warning: %s: block < 0", __func__);
 176         } else if (i_block < direct_blocks) {
 177                 offsets[n++] = i_block;
 178                 final = direct_blocks;
 179         } else if ( (i_block -= direct_blocks) < indirect_blocks) {
 180                 offsets[n++] = EXT2_IND_BLOCK;
 181                 offsets[n++] = i_block;
 182                 final = ptrs;
 183         } else if ((i_block -= indirect_blocks) < double_blocks) {
 184                 offsets[n++] = EXT2_DIND_BLOCK;
 185                 offsets[n++] = i_block >> ptrs_bits;
 186                 offsets[n++] = i_block & (ptrs - 1);
 187                 final = ptrs;
 188         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
 189                 offsets[n++] = EXT2_TIND_BLOCK;
 190                 offsets[n++] = i_block >> (ptrs_bits * 2);
 191                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
 192                 offsets[n++] = i_block & (ptrs - 1);
 193                 final = ptrs;
 194         } else {
 195                 ext2_msg(inode->i_sb, KERN_WARNING,
 196                         "warning: %s: block is too big", __func__);
 197         }
 198         if (boundary)
 199                 *boundary = final - 1 - (i_block & (ptrs - 1));
 200
 201         return n;
 202 }
 203
 204 /**
 205  *      ext2_get_branch - read the chain of indirect blocks leading to data
 206  *      @inode: inode in question
 207  *      @depth: depth of the chain (1 - direct pointer, etc.)
 208  *      @offsets: offsets of pointers in inode/indirect blocks
 209  *      @chain: place to store the result
 210  *      @err: here we store the error value
 211  *
 212  *      Function fills the array of triples <key, p, bh> and returns %NULL
 213  *      if everything went OK or the pointer to the last filled triple
 214  *      (incomplete one) otherwise. Upon the return chain[i].key contains
 215  *      the number of (i+1)-th block in the chain (as it is stored in memory,
 216  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
 217  *      number (it points into struct inode for i==0 and into the bh->b_data
 218  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
 219  *      block for i>0 and NULL for i==0. In other words, it holds the block
 220  *      numbers of the chain, addresses they were taken from (and where we can
 221  *      verify that chain did not change) and buffer_heads hosting these
 222  *      numbers.
 223  *
 224  *      Function stops when it stumbles upon zero pointer (absent block)
 225  *              (pointer to last triple returned, *@err == 0)
 226  *      or when it gets an IO error reading an indirect block
 227  *              (ditto, *@err == -EIO)
 228  *      or when it notices that chain had been changed while it was reading
 229  *              (ditto, *@err == -EAGAIN)
 230  *      or when it reads all @depth-1 indirect blocks successfully and finds
 231  *      the whole chain, all way to the data (returns %NULL, *err == 0).
 232  */
 233 static Indirect *ext2_get_branch(struct inode *inode,
 234                                  int depth,
 235                                  int *offsets,
 236                                  Indirect chain[4],
 237                                  int *err)
 238 {
 239         struct super_block *sb = inode->i_sb;
 240         Indirect *p = chain;
 241         struct buffer_head *bh;
 242
 243         *err = 0;
 244         /* i_data is not going away, no lock needed */
 245         add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
 246         if (!p->key)
 247                 goto no_block;
 248         while (--depth) {
 249                 bh = sb_bread(sb, le32_to_cpu(p->key));
 250                 if (!bh)
 251                         goto failure;
 252                 read_lock(&EXT2_I(inode)->i_meta_lock);
 253                 if (!verify_chain(chain, p))
 254                         goto changed;
 255                 add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
 256                 read_unlock(&EXT2_I(inode)->i_meta_lock);
 257                 if (!p->key)
 258                         goto no_block;
 259         }
 260         return NULL;
 261
 262 changed:
 263         read_unlock(&EXT2_I(inode)->i_meta_lock);
 264         brelse(bh);
 265         *err = -EAGAIN;
 266         goto no_block;
 267 failure:
 268         *err = -EIO;
 269 no_block:
 270         return p;
 271 }
 272
 273 /**
 274  *      ext2_find_near - find a place for allocation with sufficient locality
 275  *      @inode: owner
 276  *      @ind: descriptor of indirect block.
 277  *
 278  *      This function returns the preferred place for block allocation.
 279  *      It is used when heuristic for sequential allocation fails.
 280  *      Rules are:
 281  *        + if there is a block to the left of our position - allocate near it.
 282  *        + if pointer will live in indirect block - allocate near that block.
 283  *        + if pointer will live in inode - allocate in the same cylinder group.
 284  *
 285  * In the latter case we colour the starting block by the callers PID to
 286  * prevent it from clashing with concurrent allocations for a different inode
 287  * in the same block group.   The PID is used here so that functionally related
 288  * files will be close-by on-disk.
 289  *
 290  *      Caller must make sure that @ind is valid and will stay that way.
 291  */
 292
 293 static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
 294 {
 295         struct ext2_inode_info *ei = EXT2_I(inode);
 296         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
 297         __le32 *p;
 298         ext2_fsblk_t bg_start;
 299         ext2_fsblk_t colour;
 300
 301         /* Try to find previous block */
 302         for (p = ind->p - 1; p >= start; p--)
 303                 if (*p)
 304                         return le32_to_cpu(*p);
 305
 306         /* No such thing, so let's try location of indirect block */
 307         if (ind->bh)
 308                 return ind->bh->b_blocknr;
 309
 310         /*
 311          * It is going to be referred from inode itself? OK, just put it into
 312          * the same cylinder group then.
 313          */
 314         bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
 315         colour = (current->pid % 16) *
 316                         (EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 317         return bg_start + colour;
 318 }
 319
 320 /**
 321  *      ext2_find_goal - find a preferred place for allocation.
 322  *      @inode: owner
 323  *      @block:  block we want
 324  *      @partial: pointer to the last triple within a chain
 325  *
 326  *      Returns preferred place for a block (the goal).
 327  */
 328
 329 static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,
 330                                           Indirect *partial)
 331 {
 332         struct ext2_block_alloc_info *block_i;
 333
 334         block_i = EXT2_I(inode)->i_block_alloc_info;
 335
 336         /*
 337          * try the heuristic for sequential allocation,
 338          * failing that at least try to get decent locality.
 339          */
 340         if (block_i && (block == block_i->last_alloc_logical_block + 1)
 341                 && (block_i->last_alloc_physical_block != 0)) {
 342                 return block_i->last_alloc_physical_block + 1;
 343         }
 344
 345         return ext2_find_near(inode, partial);
 346 }
 347
 348 /**
 349  *      ext2_blks_to_allocate: Look up the block map and count the number
 350  *      of direct blocks need to be allocated for the given branch.
 351  *
 352  *      @branch: chain of indirect blocks
 353  *      @k: number of blocks need for indirect blocks
 354  *      @blks: number of data blocks to be mapped.
 355  *      @blocks_to_boundary:  the offset in the indirect block
 356  *
 357  *      return the total number of blocks to be allocate, including the
 358  *      direct and indirect blocks.
 359  */
 360 static int
 361 ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
 362                 int blocks_to_boundary)
 363 {
 364         unsigned long count = 0;
 365
 366         /*
 367          * Simple case, [t,d]Indirect block(s) has not allocated yet
 368          * then it's clear blocks on that path have not allocated
 369          */
 370         if (k > 0) {
 371                 /* right now don't hanel cross boundary allocation */
 372                 if (blks < blocks_to_boundary + 1)
 373                         count += blks;
 374                 else
 375                         count += blocks_to_boundary + 1;
 376                 return count;
 377         }
 378
 379         count++;
 380         while (count < blks && count <= blocks_to_boundary
 381                 && le32_to_cpu(*(branch[0].p + count)) == 0) {
 382                 count++;
 383         }
 384         return count;
 385 }
 386
 387 /**
 388  *      ext2_alloc_blocks: multiple allocate blocks needed for a branch
 389  *      @indirect_blks: the number of blocks need to allocate for indirect
 390  *                      blocks
 391  *
 392  *      @new_blocks: on return it will store the new block numbers for
 393  *      the indirect blocks(if needed) and the first direct block,
 394  *      @blks:  on return it will store the total number of allocated
 395  *              direct blocks
 396  */
 397 static int ext2_alloc_blocks(struct inode *inode,
 398                         ext2_fsblk_t goal, int indirect_blks, int blks,
 399                         ext2_fsblk_t new_blocks[4], int *err)
 400 {
 401         int target, i;
 402         unsigned long count = 0;
 403         int index = 0;
 404         ext2_fsblk_t current_block = 0;
 405         int ret = 0;
 406
 407         /*
 408          * Here we try to allocate the requested multiple blocks at once,
 409          * on a best-effort basis.
 410          * To build a branch, we should allocate blocks for
 411          * the indirect blocks(if not allocated yet), and at least
 412          * the first direct block of this branch.  That's the
 413          * minimum number of blocks need to allocate(required)
 414          */
 415         target = blks + indirect_blks;
 416
 417         while (1) {
 418                 count = target;
 419                 /* allocating blocks for indirect blocks and direct blocks */
 420                 current_block = ext2_new_blocks(inode,goal,&count,err);
 421                 if (*err)
 422                         goto failed_out;
 423
 424                 target -= count;
 425                 /* allocate blocks for indirect blocks */
 426                 while (index < indirect_blks && count) {
 427                         new_blocks[index++] = current_block++;
 428                         count--;
 429                 }
 430
 431                 if (count > 0)
 432                         break;
 433         }
 434
 435         /* save the new block number for the first direct block */
 436         new_blocks[index] = current_block;
 437
 438         /* total number of blocks allocated for direct blocks */
 439         ret = count;
 440         *err = 0;
 441         return ret;
 442 failed_out:
 443         for (i = 0; i <index; i++)
 444                 ext2_free_blocks(inode, new_blocks[i], 1);
 445         if (index)
 446                 mark_inode_dirty(inode);
 447         return ret;
 448 }
 449
 450 /**
 451  *      ext2_alloc_branch - allocate and set up a chain of blocks.
 452  *      @inode: owner
 453  *      @num: depth of the chain (number of blocks to allocate)
 454  *      @offsets: offsets (in the blocks) to store the pointers to next.
 455  *      @branch: place to store the chain in.
 456  *
 457  *      This function allocates @num blocks, zeroes out all but the last one,
 458  *      links them into chain and (if we are synchronous) writes them to disk.
 459  *      In other words, it prepares a branch that can be spliced onto the
 460  *      inode. It stores the information about that chain in the branch[], in
 461  *      the same format as ext2_get_branch() would do. We are calling it after
 462  *      we had read the existing part of chain and partial points to the last
 463  *      triple of that (one with zero ->key). Upon the exit we have the same
 464  *      picture as after the successful ext2_get_block(), except that in one
 465  *      place chain is disconnected - *branch->p is still zero (we did not
 466  *      set the last link), but branch->key contains the number that should
 467  *      be placed into *branch->p to fill that gap.
 468  *
 469  *      If allocation fails we free all blocks we've allocated (and forget
 470  *      their buffer_heads) and return the error value the from failed
 471  *      ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
 472  *      as described above and return 0.
 473  */
 474
 475 static int ext2_alloc_branch(struct inode *inode,
 476                         int indirect_blks, int *blks, ext2_fsblk_t goal,
 477                         int *offsets, Indirect *branch)
 478 {
 479         int blocksize = inode->i_sb->s_blocksize;
 480         int i, n = 0;
 481         int err = 0;
 482         struct buffer_head *bh;
 483         int num;
 484         ext2_fsblk_t new_blocks[4];
 485         ext2_fsblk_t current_block;
 486
 487         num = ext2_alloc_blocks(inode, goal, indirect_blks,
 488                                 *blks, new_blocks, &err);
 489         if (err)
 490                 return err;
 491
 492         branch[0].key = cpu_to_le32(new_blocks[0]);
 493         /*
 494          * metadata blocks and data blocks are allocated.
 495          */
 496         for (n = 1; n <= indirect_blks;  n++) {
 497                 /*
 498                  * Get buffer_head for parent block, zero it out
 499                  * and set the pointer to new one, then send
 500                  * parent to disk.
 501                  */
 502                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
 503                 if (unlikely(!bh)) {
 504                         err = -ENOMEM;
 505                         goto failed;
 506                 }
 507                 branch[n].bh = bh;
 508                 lock_buffer(bh);
 509                 memset(bh->b_data, 0, blocksize);
 510                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
 511                 branch[n].key = cpu_to_le32(new_blocks[n]);
 512                 *branch[n].p = branch[n].key;
 513                 if ( n == indirect_blks) {
 514                         current_block = new_blocks[n];
 515                         /*
 516                          * End of chain, update the last new metablock of
 517                          * the chain to point to the new allocated
 518                          * data blocks numbers
 519                          */
 520                         for (i=1; i < num; i++)
 521                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
 522                 }
 523                 set_buffer_uptodate(bh);
 524                 unlock_buffer(bh);
 525                 mark_buffer_dirty_inode(bh, inode);
 526                 /* We used to sync bh here if IS_SYNC(inode).
 527                  * But we now rely upon generic_write_sync()
 528                  * and b_inode_buffers.  But not for directories.
 529                  */
 530                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
 531                         sync_dirty_buffer(bh);
 532         }
 533         *blks = num;
 534         return err;
 535
 536 failed:
 537         for (i = 1; i < n; i++)
 538                 bforget(branch[i].bh);
 539         for (i = 0; i < indirect_blks; i++)
 540                 ext2_free_blocks(inode, new_blocks[i], 1);
 541         ext2_free_blocks(inode, new_blocks[i], num);
 542         return err;
 543 }
 544
 545 /**
 546  * ext2_splice_branch - splice the allocated branch onto inode.
 547  * @inode: owner
 548  * @block: (logical) number of block we are adding
 549  * @where: location of missing link
 550  * @num:   number of indirect blocks we are adding
 551  * @blks:  number of direct blocks we are adding
 552  *
 553  * This function fills the missing link and does all housekeeping needed in
 554  * inode (->i_blocks, etc.). In case of success we end up with the full
 555  * chain to new block and return 0.
 556  */
 557 static void ext2_splice_branch(struct inode *inode,
 558                         long block, Indirect *where, int num, int blks)
 559 {
 560         int i;
 561         struct ext2_block_alloc_info *block_i;
 562         ext2_fsblk_t current_block;
 563
 564         block_i = EXT2_I(inode)->i_block_alloc_info;
 565
 566         /* XXX LOCKING probably should have i_meta_lock ?*/
 567         /* That's it */
 568
 569         *where->p = where->key;
 570
 571         /*
 572          * Update the host buffer_head or inode to point to more just allocated
 573          * direct blocks blocks
 574          */
 575         if (num == 0 && blks > 1) {
 576                 current_block = le32_to_cpu(where->key) + 1;
 577                 for (i = 1; i < blks; i++)
 578                         *(where->p + i ) = cpu_to_le32(current_block++);
 579         }
 580
 581         /*
 582          * update the most recently allocated logical & physical block
 583          * in i_block_alloc_info, to assist find the proper goal block for next
 584          * allocation
 585          */
 586         if (block_i) {
 587                 block_i->last_alloc_logical_block = block + blks - 1;
 588                 block_i->last_alloc_physical_block =
 589                                 le32_to_cpu(where[num].key) + blks - 1;
 590         }
 591
 592         /* We are done with atomic stuff, now do the rest of housekeeping */
 593
 594         /* had we spliced it onto indirect block? */
 595         if (where->bh)
 596                 mark_buffer_dirty_inode(where->bh, inode);
 597
 598         inode->i_ctime = current_time(inode);
 599         mark_inode_dirty(inode);
 600 }
 601
 602 /*
 603  * Allocation strategy is simple: if we have to allocate something, we will
 604  * have to go the whole way to leaf. So let's do it before attaching anything
 605  * to tree, set linkage between the newborn blocks, write them if sync is
 606  * required, recheck the path, free and repeat if check fails, otherwise
 607  * set the last missing link (that will protect us from any truncate-generated
 608  * removals - all blocks on the path are immune now) and possibly force the
 609  * write on the parent block.
 610  * That has a nice additional property: no special recovery from the failed
 611  * allocations is needed - we simply release blocks and do not touch anything
 612  * reachable from inode.
 613  *
 614  * `handle' can be NULL if create == 0.
 615  *
 616  * return > 0, # of blocks mapped or allocated.
 617  * return = 0, if plain lookup failed.
 618  * return < 0, error case.
 619  */
 620 static int ext2_get_blocks(struct inode *inode,
 621                            sector_t iblock, unsigned long maxblocks,
 622                            u32 *bno, bool *new, bool *boundary,
 623                            int create)
 624 {
 625         int err = -EIO;
 626         int offsets[4];
 627         Indirect chain[4];
 628         Indirect *partial;
 629         ext2_fsblk_t goal;
 630         int indirect_blks;
 631         int blocks_to_boundary = 0;
 632         int depth;
 633         struct ext2_inode_info *ei = EXT2_I(inode);
 634         int count = 0;
 635         ext2_fsblk_t first_block = 0;
 636
 637         BUG_ON(maxblocks == 0);
 638
 639         depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
 640
 641         if (depth == 0)
 642                 return (err);
 643
 644         partial = ext2_get_branch(inode, depth, offsets, chain, &err);
 645         /* Simplest case - block found, no allocation needed */
 646         if (!partial) {
 647                 first_block = le32_to_cpu(chain[depth - 1].key);
 648                 count++;
 649                 /*map more blocks*/
 650                 while (count < maxblocks && count <= blocks_to_boundary) {
 651                         ext2_fsblk_t blk;
 652
 653                         if (!verify_chain(chain, chain + depth - 1)) {
 654                                 /*
 655                                  * Indirect block might be removed by
 656                                  * truncate while we were reading it.
 657                                  * Handling of that case: forget what we've
 658                                  * got now, go to reread.
 659                                  */
 660                                 err = -EAGAIN;
 661                                 count = 0;
 662                                 break;
 663                         }
 664                         blk = le32_to_cpu(*(chain[depth-1].p + count));
 665                         if (blk == first_block + count)
 666                                 count++;
 667                         else
 668                                 break;
 669                 }
 670                 if (err != -EAGAIN)
 671                         goto got_it;
 672         }
 673
 674         /* Next simple case - plain lookup or failed read of indirect block */
 675         if (!create || err == -EIO)
 676                 goto cleanup;
 677
 678         mutex_lock(&ei->truncate_mutex);
 679         /*
 680          * If the indirect block is missing while we are reading
 681          * the chain(ext2_get_branch() returns -EAGAIN err), or
 682          * if the chain has been changed after we grab the semaphore,
 683          * (either because another process truncated this branch, or
 684          * another get_block allocated this branch) re-grab the chain to see if
 685          * the request block has been allocated or not.
 686          *
 687          * Since we already block the truncate/other get_block
 688          * at this point, we will have the current copy of the chain when we
 689          * splice the branch into the tree.
 690          */
 691         if (err == -EAGAIN || !verify_chain(chain, partial)) {
 692                 while (partial > chain) {
 693                         brelse(partial->bh);
 694                         partial--;
 695                 }
 696                 partial = ext2_get_branch(inode, depth, offsets, chain, &err);
 697                 if (!partial) {
 698                         count++;
 699                         mutex_unlock(&ei->truncate_mutex);
 700                         if (err)
 701                                 goto cleanup;
 702                         goto got_it;
 703                 }
 704         }
 705
 706         /*
 707          * Okay, we need to do block allocation.  Lazily initialize the block
 708          * allocation info here if necessary
 709         */
 710         if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
 711                 ext2_init_block_alloc_info(inode);
 712
 713         goal = ext2_find_goal(inode, iblock, partial);
 714
 715         /* the number of blocks need to allocate for [d,t]indirect blocks */
 716         indirect_blks = (chain + depth) - partial - 1;
 717         /*
 718          * Next look up the indirect map to count the totoal number of
 719          * direct blocks to allocate for this branch.
 720          */
 721         count = ext2_blks_to_allocate(partial, indirect_blks,
 722                                         maxblocks, blocks_to_boundary);
 723         /*
 724          * XXX ???? Block out ext2_truncate while we alter the tree
 725          */
 726         err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
 727                                 offsets + (partial - chain), partial);
 728
 729         if (err) {
 730                 mutex_unlock(&ei->truncate_mutex);
 731                 goto cleanup;
 732         }
 733
 734         if (IS_DAX(inode)) {
 735                 int i;
 736
 737                 /*
 738                  * We must unmap blocks before zeroing so that writeback cannot
 739                  * overwrite zeros with stale data from block device page cache.
 740                  */
 741                 for (i = 0; i < count; i++) {
 742                         unmap_underlying_metadata(inode->i_sb->s_bdev,
 743                                         le32_to_cpu(chain[depth-1].key) + i);
 744                 }
 745                 /*
 746                  * block must be initialised before we put it in the tree
 747                  * so that it's not found by another thread before it's
 748                  * initialised
 749                  */
 750                 err = sb_issue_zeroout(inode->i_sb,
 751                                 le32_to_cpu(chain[depth-1].key), count,
 752                                 GFP_NOFS);
 753                 if (err) {
 754                         mutex_unlock(&ei->truncate_mutex);
 755                         goto cleanup;
 756                 }
 757         } else {
 758                 *new = true;
 759         }
 760
 761         ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
 762         mutex_unlock(&ei->truncate_mutex);
 763 got_it:
 764         *bno = le32_to_cpu(chain[depth-1].key);
 765         if (count > blocks_to_boundary)
 766                 *boundary = true;
 767         err = count;
 768         /* Clean up and exit */
 769         partial = chain + depth - 1;    /* the whole chain */
 770 cleanup:
 771         while (partial > chain) {
 772                 brelse(partial->bh);
 773                 partial--;
 774         }
 775         return err;
 776 }
 777
 778 int ext2_get_block(struct inode *inode, sector_t iblock,
 779                 struct buffer_head *bh_result, int create)
 780 {
 781         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
 782         bool new = false, boundary = false;
 783         u32 bno;
 784         int ret;
 785
 786         ret = ext2_get_blocks(inode, iblock, max_blocks, &bno, &new, &boundary,
 787                         create);
 788         if (ret <= 0)
 789                 return ret;
 790
 791         map_bh(bh_result, inode->i_sb, bno);
 792         bh_result->b_size = (ret << inode->i_blkbits);
 793         if (new)
 794                 set_buffer_new(bh_result);
 795         if (boundary)
 796                 set_buffer_boundary(bh_result);
 797         return 0;
 798
 799 }
 800
 801 #ifdef CONFIG_FS_DAX
 802 static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 803                 unsigned flags, struct iomap *iomap)
 804 {
 805         unsigned int blkbits = inode->i_blkbits;
 806         unsigned long first_block = offset >> blkbits;
 807         unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
 808         bool new = false, boundary = false;
 809         u32 bno;
 810         int ret;
 811
 812         ret = ext2_get_blocks(inode, first_block, max_blocks,
 813                         &bno, &new, &boundary, flags & IOMAP_WRITE);
 814         if (ret < 0)
 815                 return ret;
 816
 817         iomap->flags = 0;
 818         iomap->bdev = inode->i_sb->s_bdev;
 819         iomap->offset = (u64)first_block << blkbits;
 820
 821         if (ret == 0) {
 822                 iomap->type = IOMAP_HOLE;
 823                 iomap->blkno = IOMAP_NULL_BLOCK;
 824                 iomap->length = 1 << blkbits;
 825         } else {
 826                 iomap->type = IOMAP_MAPPED;
 827                 iomap->blkno = (sector_t)bno << (blkbits - 9);
 828                 iomap->length = (u64)ret << blkbits;
 829                 iomap->flags |= IOMAP_F_MERGED;
 830         }
 831
 832         if (new)
 833                 iomap->flags |= IOMAP_F_NEW;
 834         return 0;
 835 }
 836
 837 static int
 838 ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
 839                 ssize_t written, unsigned flags, struct iomap *iomap)
 840 {
 841         if (iomap->type == IOMAP_MAPPED &&
 842             written < length &&
 843             (flags & IOMAP_WRITE))
 844                 ext2_write_failed(inode->i_mapping, offset + length);
 845         return 0;
 846 }
 847
 848 struct iomap_ops ext2_iomap_ops = {
 849         .iomap_begin            = ext2_iomap_begin,
 850         .iomap_end              = ext2_iomap_end,
 851 };
 852 #endif /* CONFIG_FS_DAX */
 853
 854 int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 855                 u64 start, u64 len)
 856 {
 857         return generic_block_fiemap(inode, fieinfo, start, len,
 858                                     ext2_get_block);
 859 }
 860
 861 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
 862 {
 863         return block_write_full_page(page, ext2_get_block, wbc);
 864 }
 865
 866 static int ext2_readpage(struct file *file, struct page *page)
 867 {
 868         return mpage_readpage(page, ext2_get_block);
 869 }
 870
 871 static int
 872 ext2_readpages(struct file *file, struct address_space *mapping,
 873                 struct list_head *pages, unsigned nr_pages)
 874 {
 875         return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
 876 }
 877
 878 static int
 879 ext2_write_begin(struct file *file, struct address_space *mapping,
 880                 loff_t pos, unsigned len, unsigned flags,
 881                 struct page **pagep, void **fsdata)
 882 {
 883         int ret;
 884
 885         ret = block_write_begin(mapping, pos, len, flags, pagep,
 886                                 ext2_get_block);
 887         if (ret < 0)
 888                 ext2_write_failed(mapping, pos + len);
 889         return ret;
 890 }
 891
 892 static int ext2_write_end(struct file *file, struct address_space *mapping,
 893                         loff_t pos, unsigned len, unsigned copied,
 894                         struct page *page, void *fsdata)
 895 {
 896         int ret;
 897
 898         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 899         if (ret < len)
 900                 ext2_write_failed(mapping, pos + len);
 901         return ret;
 902 }
 903
 904 static int
 905 ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
 906                 loff_t pos, unsigned len, unsigned flags,
 907                 struct page **pagep, void **fsdata)
 908 {
 909         int ret;
 910
 911         ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
 912                                ext2_get_block);
 913         if (ret < 0)
 914                 ext2_write_failed(mapping, pos + len);
 915         return ret;
 916 }
 917
 918 static int ext2_nobh_writepage(struct page *page,
 919                         struct writeback_control *wbc)
 920 {
 921         return nobh_writepage(page, ext2_get_block, wbc);
 922 }
 923
 924 static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
 925 {
 926         return generic_block_bmap(mapping,block,ext2_get_block);
 927 }
 928
 929 static ssize_t
 930 ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 931 {
 932         struct file *file = iocb->ki_filp;
 933         struct address_space *mapping = file->f_mapping;
 934         struct inode *inode = mapping->host;
 935         size_t count = iov_iter_count(iter);
 936         loff_t offset = iocb->ki_pos;
 937         ssize_t ret;
 938
 939         if (WARN_ON_ONCE(IS_DAX(inode)))
 940                 return -EIO;
 941
 942         ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
 943         if (ret < 0 && iov_iter_rw(iter) == WRITE)
 944                 ext2_write_failed(mapping, offset + count);
 945         return ret;
 946 }
 947
 948 static int
 949 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 950 {
 951 #ifdef CONFIG_FS_DAX
 952         if (dax_mapping(mapping)) {
 953                 return dax_writeback_mapping_range(mapping,
 954                                                    mapping->host->i_sb->s_bdev,
 955                                                    wbc);
 956         }
 957 #endif
 958
 959         return mpage_writepages(mapping, wbc, ext2_get_block);
 960 }
 961
 962 const struct address_space_operations ext2_aops = {
 963         .readpage               = ext2_readpage,
 964         .readpages              = ext2_readpages,
 965         .writepage              = ext2_writepage,
 966         .write_begin            = ext2_write_begin,
 967         .write_end              = ext2_write_end,
 968         .bmap                   = ext2_bmap,
 969         .direct_IO              = ext2_direct_IO,
 970         .writepages             = ext2_writepages,
 971         .migratepage            = buffer_migrate_page,
 972         .is_partially_uptodate  = block_is_partially_uptodate,
 973         .error_remove_page      = generic_error_remove_page,
 974 };
 975
 976 const struct address_space_operations ext2_nobh_aops = {
 977         .readpage               = ext2_readpage,
 978         .readpages              = ext2_readpages,
 979         .writepage              = ext2_nobh_writepage,
 980         .write_begin            = ext2_nobh_write_begin,
 981         .write_end              = nobh_write_end,
 982         .bmap                   = ext2_bmap,
 983         .direct_IO              = ext2_direct_IO,
 984         .writepages             = ext2_writepages,
 985         .migratepage            = buffer_migrate_page,
 986         .error_remove_page      = generic_error_remove_page,
 987 };
 988
 989 /*
 990  * Probably it should be a library function... search for first non-zero word
 991  * or memcmp with zero_page, whatever is better for particular architecture.
 992  * Linus?
 993  */
 994 static inline int all_zeroes(__le32 *p, __le32 *q)
 995 {
 996         while (p < q)
 997                 if (*p++)
 998                         return 0;
 999         return 1;
1000 }
1001
1002 /**
1003  *      ext2_find_shared - find the indirect blocks for partial truncation.
1004  *      @inode:   inode in question
1005  *      @depth:   depth of the affected branch
1006  *      @offsets: offsets of pointers in that branch (see ext2_block_to_path)
1007  *      @chain:   place to store the pointers to partial indirect blocks
1008  *      @top:     place to the (detached) top of branch
1009  *
1010  *      This is a helper function used by ext2_truncate().
1011  *
1012  *      When we do truncate() we may have to clean the ends of several indirect
1013  *      blocks but leave the blocks themselves alive. Block is partially
1014  *      truncated if some data below the new i_size is referred from it (and
1015  *      it is on the path to the first completely truncated data block, indeed).
1016  *      We have to free the top of that path along with everything to the right
1017  *      of the path. Since no allocation past the truncation point is possible
1018  *      until ext2_truncate() finishes, we may safely do the latter, but top
1019  *      of branch may require special attention - pageout below the truncation
1020  *      point might try to populate it.
1021  *
1022  *      We atomically detach the top of branch from the tree, store the block
1023  *      number of its root in *@top, pointers to buffer_heads of partially
1024  *      truncated blocks - in @chain[].bh and pointers to their last elements
1025  *      that should not be removed - in @chain[].p. Return value is the pointer
1026  *      to last filled element of @chain.
1027  *
1028  *      The work left to caller to do the actual freeing of subtrees:
1029  *              a) free the subtree starting from *@top
1030  *              b) free the subtrees whose roots are stored in
1031  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
1032  *              c) free the subtrees growing from the inode past the @chain[0].p
1033  *                      (no partially truncated stuff there).
1034  */
1035
1036 static Indirect *ext2_find_shared(struct inode *inode,
1037                                 int depth,
1038                                 int offsets[4],
1039                                 Indirect chain[4],
1040                                 __le32 *top)
1041 {
1042         Indirect *partial, *p;
1043         int k, err;
1044
1045         *top = 0;
1046         for (k = depth; k > 1 && !offsets[k-1]; k--)
1047                 ;
1048         partial = ext2_get_branch(inode, k, offsets, chain, &err);
1049         if (!partial)
1050                 partial = chain + k-1;
1051         /*
1052          * If the branch acquired continuation since we've looked at it -
1053          * fine, it should all survive and (new) top doesn't belong to us.
1054          */
1055         write_lock(&EXT2_I(inode)->i_meta_lock);
1056         if (!partial->key && *partial->p) {
1057                 write_unlock(&EXT2_I(inode)->i_meta_lock);
1058                 goto no_top;
1059         }
1060         for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
1061                 ;
1062         /*
1063          * OK, we've found the last block that must survive. The rest of our
1064          * branch should be detached before unlocking. However, if that rest
1065          * of branch is all ours and does not grow immediately from the inode
1066          * it's easier to cheat and just decrement partial->p.
1067          */
1068         if (p == chain + k - 1 && p > chain) {
1069                 p->p--;
1070         } else {
1071                 *top = *p->p;
1072                 *p->p = 0;
1073         }
1074         write_unlock(&EXT2_I(inode)->i_meta_lock);
1075
1076         while(partial > p)
1077         {
1078                 brelse(partial->bh);
1079                 partial--;
1080         }
1081 no_top:
1082         return partial;
1083 }
1084
1085 /**
1086  *      ext2_free_data - free a list of data blocks
1087  *      @inode: inode we are dealing with
1088  *      @p:     array of block numbers
1089  *      @q:     points immediately past the end of array
1090  *
1091  *      We are freeing all blocks referred from that array (numbers are
1092  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1093  *      appropriately.
1094  */
1095 static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
1096 {
1097         unsigned long block_to_free = 0, count = 0;
1098         unsigned long nr;
1099
1100         for ( ; p < q ; p++) {
1101                 nr = le32_to_cpu(*p);
1102                 if (nr) {
1103                         *p = 0;
1104                         /* accumulate blocks to free if they're contiguous */
1105                         if (count == 0)
1106                                 goto free_this;
1107                         else if (block_to_free == nr - count)
1108                                 count++;
1109                         else {
1110                                 ext2_free_blocks (inode, block_to_free, count);
1111                                 mark_inode_dirty(inode);
1112                         free_this:
1113                                 block_to_free = nr;
1114                                 count = 1;
1115                         }
1116                 }
1117         }
1118         if (count > 0) {
1119                 ext2_free_blocks (inode, block_to_free, count);
1120                 mark_inode_dirty(inode);
1121         }
1122 }
1123
1124 /**
1125  *      ext2_free_branches - free an array of branches
1126  *      @inode: inode we are dealing with
1127  *      @p:     array of block numbers
1128  *      @q:     pointer immediately past the end of array
1129  *      @depth: depth of the branches to free
1130  *
1131  *      We are freeing all blocks referred from these branches (numbers are
1132  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1133  *      appropriately.
1134  */
1135 static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
1136 {
1137         struct buffer_head * bh;
1138         unsigned long nr;
1139
1140         if (depth--) {
1141                 int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1142                 for ( ; p < q ; p++) {
1143                         nr = le32_to_cpu(*p);
1144                         if (!nr)
1145                                 continue;
1146                         *p = 0;
1147                         bh = sb_bread(inode->i_sb, nr);
1148                         /*
1149                          * A read failure? Report error and clear slot
1150                          * (should be rare).
1151                          */
1152                         if (!bh) {
1153                                 ext2_error(inode->i_sb, "ext2_free_branches",
1154                                         "Read failure, inode=%ld, block=%ld",
1155                                         inode->i_ino, nr);
1156                                 continue;
1157                         }
1158                         ext2_free_branches(inode,
1159                                            (__le32*)bh->b_data,
1160                                            (__le32*)bh->b_data + addr_per_block,
1161                                            depth);
1162                         bforget(bh);
1163                         ext2_free_blocks(inode, nr, 1);
1164                         mark_inode_dirty(inode);
1165                 }
1166         } else
1167                 ext2_free_data(inode, p, q);
1168 }
1169
1170 /* dax_sem must be held when calling this function */
1171 static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
1172 {
1173         __le32 *i_data = EXT2_I(inode)->i_data;
1174         struct ext2_inode_info *ei = EXT2_I(inode);
1175         int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1176         int offsets[4];
1177         Indirect chain[4];
1178         Indirect *partial;
1179         __le32 nr = 0;
1180         int n;
1181         long iblock;
1182         unsigned blocksize;
1183         blocksize = inode->i_sb->s_blocksize;
1184         iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
1185
1186 #ifdef CONFIG_FS_DAX
1187         WARN_ON(!rwsem_is_locked(&ei->dax_sem));
1188 #endif
1189
1190         n = ext2_block_to_path(inode, iblock, offsets, NULL);
1191         if (n == 0)
1192                 return;
1193
1194         /*
1195          * From here we block out all ext2_get_block() callers who want to
1196          * modify the block allocation tree.
1197          */
1198         mutex_lock(&ei->truncate_mutex);
1199
1200         if (n == 1) {
1201                 ext2_free_data(inode, i_data+offsets[0],
1202                                         i_data + EXT2_NDIR_BLOCKS);
1203                 goto do_indirects;
1204         }
1205
1206         partial = ext2_find_shared(inode, n, offsets, chain, &nr);
1207         /* Kill the top of shared branch (already detached) */
1208         if (nr) {
1209                 if (partial == chain)
1210                         mark_inode_dirty(inode);
1211                 else
1212                         mark_buffer_dirty_inode(partial->bh, inode);
1213                 ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
1214         }
1215         /* Clear the ends of indirect blocks on the shared branch */
1216         while (partial > chain) {
1217                 ext2_free_branches(inode,
1218                                    partial->p + 1,
1219                                    (__le32*)partial->bh->b_data+addr_per_block,
1220                                    (chain+n-1) - partial);
1221                 mark_buffer_dirty_inode(partial->bh, inode);
1222                 brelse (partial->bh);
1223                 partial--;
1224         }
1225 do_indirects:
1226         /* Kill the remaining (whole) subtrees */
1227         switch (offsets[0]) {
1228                 default:
1229                         nr = i_data[EXT2_IND_BLOCK];
1230                         if (nr) {
1231                                 i_data[EXT2_IND_BLOCK] = 0;
1232                                 mark_inode_dirty(inode);
1233                                 ext2_free_branches(inode, &nr, &nr+1, 1);
1234                         }
1235                 case EXT2_IND_BLOCK:
1236                         nr = i_data[EXT2_DIND_BLOCK];
1237                         if (nr) {
1238                                 i_data[EXT2_DIND_BLOCK] = 0;
1239                                 mark_inode_dirty(inode);
1240                                 ext2_free_branches(inode, &nr, &nr+1, 2);
1241                         }
1242                 case EXT2_DIND_BLOCK:
1243                         nr = i_data[EXT2_TIND_BLOCK];
1244                         if (nr) {
1245                                 i_data[EXT2_TIND_BLOCK] = 0;
1246                                 mark_inode_dirty(inode);
1247                                 ext2_free_branches(inode, &nr, &nr+1, 3);
1248                         }
1249                 case EXT2_TIND_BLOCK:
1250                         ;
1251         }
1252
1253         ext2_discard_reservation(inode);
1254
1255         mutex_unlock(&ei->truncate_mutex);
1256 }
1257
1258 static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
1259 {
1260         /*
1261          * XXX: it seems like a bug here that we don't allow
1262          * IS_APPEND inode to have blocks-past-i_size trimmed off.
1263          * review and fix this.
1264          *
1265          * Also would be nice to be able to handle IO errors and such,
1266          * but that's probably too much to ask.
1267          */
1268         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1269             S_ISLNK(inode->i_mode)))
1270                 return;
1271         if (ext2_inode_is_fast_symlink(inode))
1272                 return;
1273         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1274                 return;
1275
1276         dax_sem_down_write(EXT2_I(inode));
1277         __ext2_truncate_blocks(inode, offset);
1278         dax_sem_up_write(EXT2_I(inode));
1279 }
1280
1281 static int ext2_setsize(struct inode *inode, loff_t newsize)
1282 {
1283         int error;
1284
1285         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1286             S_ISLNK(inode->i_mode)))
1287                 return -EINVAL;
1288         if (ext2_inode_is_fast_symlink(inode))
1289                 return -EINVAL;
1290         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1291                 return -EPERM;
1292
1293         inode_dio_wait(inode);
1294
1295         if (IS_DAX(inode))
1296                 error = dax_truncate_page(inode, newsize, ext2_get_block);
1297         else if (test_opt(inode->i_sb, NOBH))
1298                 error = nobh_truncate_page(inode->i_mapping,
1299                                 newsize, ext2_get_block);
1300         else
1301                 error = block_truncate_page(inode->i_mapping,
1302                                 newsize, ext2_get_block);
1303         if (error)
1304                 return error;
1305
1306         dax_sem_down_write(EXT2_I(inode));
1307         truncate_setsize(inode, newsize);
1308         __ext2_truncate_blocks(inode, newsize);
1309         dax_sem_up_write(EXT2_I(inode));
1310
1311         inode->i_mtime = inode->i_ctime = current_time(inode);
1312         if (inode_needs_sync(inode)) {
1313                 sync_mapping_buffers(inode->i_mapping);
1314                 sync_inode_metadata(inode, 1);
1315         } else {
1316                 mark_inode_dirty(inode);
1317         }
1318
1319         return 0;
1320 }
1321
1322 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
1323                                         struct buffer_head **p)
1324 {
1325         struct buffer_head * bh;
1326         unsigned long block_group;
1327         unsigned long block;
1328         unsigned long offset;
1329         struct ext2_group_desc * gdp;
1330
1331         *p = NULL;
1332         if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
1333             ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
1334                 goto Einval;
1335
1336         block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
1337         gdp = ext2_get_group_desc(sb, block_group, NULL);
1338         if (!gdp)
1339                 goto Egdp;
1340         /*
1341          * Figure out the offset within the block group inode table
1342          */
1343         offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
1344         block = le32_to_cpu(gdp->bg_inode_table) +
1345                 (offset >> EXT2_BLOCK_SIZE_BITS(sb));
1346         if (!(bh = sb_bread(sb, block)))
1347                 goto Eio;
1348
1349         *p = bh;
1350         offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1351         return (struct ext2_inode *) (bh->b_data + offset);
1352
1353 Einval:
1354         ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1355                    (unsigned long) ino);
1356         return ERR_PTR(-EINVAL);
1357 Eio:
1358         ext2_error(sb, "ext2_get_inode",
1359                    "unable to read inode block - inode=%lu, block=%lu",
1360                    (unsigned long) ino, block);
1361 Egdp:
1362         return ERR_PTR(-EIO);
1363 }
1364
1365 void ext2_set_inode_flags(struct inode *inode)
1366 {
1367         unsigned int flags = EXT2_I(inode)->i_flags;
1368
1369         inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
1370                                 S_DIRSYNC | S_DAX);
1371         if (flags & EXT2_SYNC_FL)
1372                 inode->i_flags |= S_SYNC;
1373         if (flags & EXT2_APPEND_FL)
1374                 inode->i_flags |= S_APPEND;
1375         if (flags & EXT2_IMMUTABLE_FL)
1376                 inode->i_flags |= S_IMMUTABLE;
1377         if (flags & EXT2_NOATIME_FL)
1378                 inode->i_flags |= S_NOATIME;
1379         if (flags & EXT2_DIRSYNC_FL)
1380                 inode->i_flags |= S_DIRSYNC;
1381         if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
1382                 inode->i_flags |= S_DAX;
1383 }
1384
1385 /* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
1386 void ext2_get_inode_flags(struct ext2_inode_info *ei)
1387 {
1388         unsigned int flags = ei->vfs_inode.i_flags;
1389
1390         ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
1391                         EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
1392         if (flags & S_SYNC)
1393                 ei->i_flags |= EXT2_SYNC_FL;
1394         if (flags & S_APPEND)
1395                 ei->i_flags |= EXT2_APPEND_FL;
1396         if (flags & S_IMMUTABLE)
1397                 ei->i_flags |= EXT2_IMMUTABLE_FL;
1398         if (flags & S_NOATIME)
1399                 ei->i_flags |= EXT2_NOATIME_FL;
1400         if (flags & S_DIRSYNC)
1401                 ei->i_flags |= EXT2_DIRSYNC_FL;
1402 }
1403
1404 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
1405 {
1406         struct ext2_inode_info *ei;
1407         struct buffer_head * bh;
1408         struct ext2_inode *raw_inode;
1409         struct inode *inode;
1410         long ret = -EIO;
1411         int n;
1412         uid_t i_uid;
1413         gid_t i_gid;
1414
1415         inode = iget_locked(sb, ino);
1416         if (!inode)
1417                 return ERR_PTR(-ENOMEM);
1418         if (!(inode->i_state & I_NEW))
1419                 return inode;
1420
1421         ei = EXT2_I(inode);
1422         ei->i_block_alloc_info = NULL;
1423
1424         raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1425         if (IS_ERR(raw_inode)) {
1426                 ret = PTR_ERR(raw_inode);
1427                 goto bad_inode;
1428         }
1429
1430         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1431         i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1432         i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1433         if (!(test_opt (inode->i_sb, NO_UID32))) {
1434                 i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1435                 i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1436         }
1437         i_uid_write(inode, i_uid);
1438         i_gid_write(inode, i_gid);
1439         set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
1440         inode->i_size = le32_to_cpu(raw_inode->i_size);
1441         inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
1442         inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
1443         inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
1444         inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1445         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1446         /* We now have enough fields to check if the inode was active or not.
1447          * This is needed because nfsd might try to access dead inodes
1448          * the test is that same one that e2fsck uses
1449          * NeilBrown 1999oct15
1450          */
1451         if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1452                 /* this inode is deleted */
1453                 brelse (bh);
1454                 ret = -ESTALE;
1455                 goto bad_inode;
1456         }
1457         inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1458         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1459         ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1460         ei->i_frag_no = raw_inode->i_frag;
1461         ei->i_frag_size = raw_inode->i_fsize;
1462         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1463         ei->i_dir_acl = 0;
1464
1465         if (ei->i_file_acl &&
1466             !ext2_data_block_valid(EXT2_SB(sb), ei->i_file_acl, 1)) {
1467                 ext2_error(sb, "ext2_iget", "bad extended attribute block %u",
1468                            ei->i_file_acl);
1469                 brelse(bh);
1470                 ret = -EFSCORRUPTED;
1471                 goto bad_inode;
1472         }
1473
1474         if (S_ISREG(inode->i_mode))
1475                 inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1476         else
1477                 ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1478         ei->i_dtime = 0;
1479         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1480         ei->i_state = 0;
1481         ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1482         ei->i_dir_start_lookup = 0;
1483
1484         /*
1485          * NOTE! The in-memory inode i_data array is in little-endian order
1486          * even on big-endian machines: we do NOT byteswap the block numbers!
1487          */
1488         for (n = 0; n < EXT2_N_BLOCKS; n++)
1489                 ei->i_data[n] = raw_inode->i_block[n];
1490
1491         if (S_ISREG(inode->i_mode)) {
1492                 inode->i_op = &ext2_file_inode_operations;
1493                 if (test_opt(inode->i_sb, NOBH)) {
1494                         inode->i_mapping->a_ops = &ext2_nobh_aops;
1495                         inode->i_fop = &ext2_file_operations;
1496                 } else {
1497                         inode->i_mapping->a_ops = &ext2_aops;
1498                         inode->i_fop = &ext2_file_operations;
1499                 }
1500         } else if (S_ISDIR(inode->i_mode)) {
1501                 inode->i_op = &ext2_dir_inode_operations;
1502                 inode->i_fop = &ext2_dir_operations;
1503                 if (test_opt(inode->i_sb, NOBH))
1504                         inode->i_mapping->a_ops = &ext2_nobh_aops;
1505                 else
1506                         inode->i_mapping->a_ops = &ext2_aops;
1507         } else if (S_ISLNK(inode->i_mode)) {
1508                 if (ext2_inode_is_fast_symlink(inode)) {
1509                         inode->i_link = (char *)ei->i_data;
1510                         inode->i_op = &ext2_fast_symlink_inode_operations;
1511                         nd_terminate_link(ei->i_data, inode->i_size,
1512                                 sizeof(ei->i_data) - 1);
1513                 } else {
1514                         inode->i_op = &ext2_symlink_inode_operations;
1515                         inode_nohighmem(inode);
1516                         if (test_opt(inode->i_sb, NOBH))
1517                                 inode->i_mapping->a_ops = &ext2_nobh_aops;
1518                         else
1519                                 inode->i_mapping->a_ops = &ext2_aops;
1520                 }
1521         } else {
1522                 inode->i_op = &ext2_special_inode_operations;
1523                 if (raw_inode->i_block[0])
1524                         init_special_inode(inode, inode->i_mode,
1525                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1526                 else
1527                         init_special_inode(inode, inode->i_mode,
1528                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1529         }
1530         brelse (bh);
1531         ext2_set_inode_flags(inode);
1532         unlock_new_inode(inode);
1533         return inode;
1534
1535 bad_inode:
1536         iget_failed(inode);
1537         return ERR_PTR(ret);
1538 }
1539
1540 static int __ext2_write_inode(struct inode *inode, int do_sync)
1541 {
1542         struct ext2_inode_info *ei = EXT2_I(inode);
1543         struct super_block *sb = inode->i_sb;
1544         ino_t ino = inode->i_ino;
1545         uid_t uid = i_uid_read(inode);
1546         gid_t gid = i_gid_read(inode);
1547         struct buffer_head * bh;
1548         struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1549         int n;
1550         int err = 0;
1551
1552         if (IS_ERR(raw_inode))
1553                 return -EIO;
1554
1555         /* For fields not not tracking in the in-memory inode,
1556          * initialise them to zero for new inodes. */
1557         if (ei->i_state & EXT2_STATE_NEW)
1558                 memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1559
1560         ext2_get_inode_flags(ei);
1561         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1562         if (!(test_opt(sb, NO_UID32))) {
1563                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1564                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1565 /*
1566  * Fix up interoperability with old kernels. Otherwise, old inodes get
1567  * re-used with the upper 16 bits of the uid/gid intact
1568  */
1569                 if (!ei->i_dtime) {
1570                         raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1571                         raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1572                 } else {
1573                         raw_inode->i_uid_high = 0;
1574                         raw_inode->i_gid_high = 0;
1575                 }
1576         } else {
1577                 raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1578                 raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1579                 raw_inode->i_uid_high = 0;
1580                 raw_inode->i_gid_high = 0;
1581         }
1582         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1583         raw_inode->i_size = cpu_to_le32(inode->i_size);
1584         raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1585         raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1586         raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1587
1588         raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1589         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1590         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1591         raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1592         raw_inode->i_frag = ei->i_frag_no;
1593         raw_inode->i_fsize = ei->i_frag_size;
1594         raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1595         if (!S_ISREG(inode->i_mode))
1596                 raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1597         else {
1598                 raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1599                 if (inode->i_size > 0x7fffffffULL) {
1600                         if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1601                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1602                             EXT2_SB(sb)->s_es->s_rev_level ==
1603                                         cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1604                                /* If this is the first large file
1605                                 * created, add a flag to the superblock.
1606                                 */
1607                                 spin_lock(&EXT2_SB(sb)->s_lock);
1608                                 ext2_update_dynamic_rev(sb);
1609                                 EXT2_SET_RO_COMPAT_FEATURE(sb,
1610                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1611                                 spin_unlock(&EXT2_SB(sb)->s_lock);
1612                                 ext2_write_super(sb);
1613                         }
1614                 }
1615         }
1616
1617         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1618         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1619                 if (old_valid_dev(inode->i_rdev)) {
1620                         raw_inode->i_block[0] =
1621                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
1622                         raw_inode->i_block[1] = 0;
1623                 } else {
1624                         raw_inode->i_block[0] = 0;
1625                         raw_inode->i_block[1] =
1626                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
1627                         raw_inode->i_block[2] = 0;
1628                 }
1629         } else for (n = 0; n < EXT2_N_BLOCKS; n++)
1630                 raw_inode->i_block[n] = ei->i_data[n];
1631         mark_buffer_dirty(bh);
1632         if (do_sync) {
1633                 sync_dirty_buffer(bh);
1634                 if (buffer_req(bh) && !buffer_uptodate(bh)) {
1635                         printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1636                                 sb->s_id, (unsigned long) ino);
1637                         err = -EIO;
1638                 }
1639         }
1640         ei->i_state &= ~EXT2_STATE_NEW;
1641         brelse (bh);
1642         return err;
1643 }
1644
1645 int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
1646 {
1647         return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
1648 }
1649
1650 int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1651 {
1652         struct inode *inode = d_inode(dentry);
1653         int error;
1654
1655         error = setattr_prepare(dentry, iattr);
1656         if (error)
1657                 return error;
1658
1659         if (is_quota_modification(inode, iattr)) {
1660                 error = dquot_initialize(inode);
1661                 if (error)
1662                         return error;
1663         }
1664         if ((iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)) ||
1665             (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))) {
1666                 error = dquot_transfer(inode, iattr);
1667                 if (error)
1668                         return error;
1669         }
1670         if (iattr->ia_valid & ATTR_SIZE && iattr->ia_size != inode->i_size) {
1671                 error = ext2_setsize(inode, iattr->ia_size);
1672                 if (error)
1673                         return error;
1674         }
1675         setattr_copy(inode, iattr);
1676         if (iattr->ia_valid & ATTR_MODE)
1677                 error = posix_acl_chmod(inode, inode->i_mode);
1678         mark_inode_dirty(inode);
1679
1680         return error;
1681 }