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Linux/fs/ext2/inode.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  linux/fs/ext2/inode.c
  4  *
  5  * Copyright (C) 1992, 1993, 1994, 1995
  6  * Remy Card (card@masi.ibp.fr)
  7  * Laboratoire MASI - Institut Blaise Pascal
  8  * Universite Pierre et Marie Curie (Paris VI)
  9  *
 10  *  from
 11  *
 12  *  linux/fs/minix/inode.c
 13  *
 14  *  Copyright (C) 1991, 1992  Linus Torvalds
 15  *
 16  *  Goal-directed block allocation by Stephen Tweedie
 17  *      (sct@dcs.ed.ac.uk), 1993, 1998
 18  *  Big-endian to little-endian byte-swapping/bitmaps by
 19  *        David S. Miller (davem@caip.rutgers.edu), 1995
 20  *  64-bit file support on 64-bit platforms by Jakub Jelinek
 21  *      (jj@sunsite.ms.mff.cuni.cz)
 22  *
 23  *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
 24  */
 25 
 26 #include <linux/time.h>
 27 #include <linux/highuid.h>
 28 #include <linux/pagemap.h>
 29 #include <linux/dax.h>
 30 #include <linux/blkdev.h>
 31 #include <linux/quotaops.h>
 32 #include <linux/writeback.h>
 33 #include <linux/buffer_head.h>
 34 #include <linux/mpage.h>
 35 #include <linux/fiemap.h>
 36 #include <linux/iomap.h>
 37 #include <linux/namei.h>
 38 #include <linux/uio.h>
 39 #include "ext2.h"
 40 #include "acl.h"
 41 #include "xattr.h"
 42 
 43 static int __ext2_write_inode(struct inode *inode, int do_sync);
 44 
 45 /*
 46  * Test whether an inode is a fast symlink.
 47  */
 48 static inline int ext2_inode_is_fast_symlink(struct inode *inode)
 49 {
 50         int ea_blocks = EXT2_I(inode)->i_file_acl ?
 51                 (inode->i_sb->s_blocksize >> 9) : 0;
 52 
 53         return (S_ISLNK(inode->i_mode) &&
 54                 inode->i_blocks - ea_blocks == 0);
 55 }
 56 
 57 static void ext2_truncate_blocks(struct inode *inode, loff_t offset);
 58 
 59 static void ext2_write_failed(struct address_space *mapping, loff_t to)
 60 {
 61         struct inode *inode = mapping->host;
 62 
 63         if (to > inode->i_size) {
 64                 truncate_pagecache(inode, inode->i_size);
 65                 ext2_truncate_blocks(inode, inode->i_size);
 66         }
 67 }
 68 
 69 /*
 70  * Called at the last iput() if i_nlink is zero.
 71  */
 72 void ext2_evict_inode(struct inode * inode)
 73 {
 74         struct ext2_block_alloc_info *rsv;
 75         int want_delete = 0;
 76 
 77         if (!inode->i_nlink && !is_bad_inode(inode)) {
 78                 want_delete = 1;
 79                 dquot_initialize(inode);
 80         } else {
 81                 dquot_drop(inode);
 82         }
 83 
 84         truncate_inode_pages_final(&inode->i_data);
 85 
 86         if (want_delete) {
 87                 sb_start_intwrite(inode->i_sb);
 88                 /* set dtime */
 89                 EXT2_I(inode)->i_dtime  = get_seconds();
 90                 mark_inode_dirty(inode);
 91                 __ext2_write_inode(inode, inode_needs_sync(inode));
 92                 /* truncate to 0 */
 93                 inode->i_size = 0;
 94                 if (inode->i_blocks)
 95                         ext2_truncate_blocks(inode, 0);
 96                 ext2_xattr_delete_inode(inode);
 97         }
 98 
 99         invalidate_inode_buffers(inode);
100         clear_inode(inode);
101 
102         ext2_discard_reservation(inode);
103         rsv = EXT2_I(inode)->i_block_alloc_info;
104         EXT2_I(inode)->i_block_alloc_info = NULL;
105         if (unlikely(rsv))
106                 kfree(rsv);
107 
108         if (want_delete) {
109                 ext2_free_inode(inode);
110                 sb_end_intwrite(inode->i_sb);
111         }
112 }
113 
114 typedef struct {
115         __le32  *p;
116         __le32  key;
117         struct buffer_head *bh;
118 } Indirect;
119 
120 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
121 {
122         p->key = *(p->p = v);
123         p->bh = bh;
124 }
125 
126 static inline int verify_chain(Indirect *from, Indirect *to)
127 {
128         while (from <= to && from->key == *from->p)
129                 from++;
130         return (from > to);
131 }
132 
133 /**
134  *      ext2_block_to_path - parse the block number into array of offsets
135  *      @inode: inode in question (we are only interested in its superblock)
136  *      @i_block: block number to be parsed
137  *      @offsets: array to store the offsets in
138  *      @boundary: set this non-zero if the referred-to block is likely to be
139  *             followed (on disk) by an indirect block.
140  *      To store the locations of file's data ext2 uses a data structure common
141  *      for UNIX filesystems - tree of pointers anchored in the inode, with
142  *      data blocks at leaves and indirect blocks in intermediate nodes.
143  *      This function translates the block number into path in that tree -
144  *      return value is the path length and @offsets[n] is the offset of
145  *      pointer to (n+1)th node in the nth one. If @block is out of range
146  *      (negative or too large) warning is printed and zero returned.
147  *
148  *      Note: function doesn't find node addresses, so no IO is needed. All
149  *      we need to know is the capacity of indirect blocks (taken from the
150  *      inode->i_sb).
151  */
152 
153 /*
154  * Portability note: the last comparison (check that we fit into triple
155  * indirect block) is spelled differently, because otherwise on an
156  * architecture with 32-bit longs and 8Kb pages we might get into trouble
157  * if our filesystem had 8Kb blocks. We might use long long, but that would
158  * kill us on x86. Oh, well, at least the sign propagation does not matter -
159  * i_block would have to be negative in the very beginning, so we would not
160  * get there at all.
161  */
162 
163 static int ext2_block_to_path(struct inode *inode,
164                         long i_block, int offsets[4], int *boundary)
165 {
166         int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
167         int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
168         const long direct_blocks = EXT2_NDIR_BLOCKS,
169                 indirect_blocks = ptrs,
170                 double_blocks = (1 << (ptrs_bits * 2));
171         int n = 0;
172         int final = 0;
173 
174         if (i_block < 0) {
175                 ext2_msg(inode->i_sb, KERN_WARNING,
176                         "warning: %s: block < 0", __func__);
177         } else if (i_block < direct_blocks) {
178                 offsets[n++] = i_block;
179                 final = direct_blocks;
180         } else if ( (i_block -= direct_blocks) < indirect_blocks) {
181                 offsets[n++] = EXT2_IND_BLOCK;
182                 offsets[n++] = i_block;
183                 final = ptrs;
184         } else if ((i_block -= indirect_blocks) < double_blocks) {
185                 offsets[n++] = EXT2_DIND_BLOCK;
186                 offsets[n++] = i_block >> ptrs_bits;
187                 offsets[n++] = i_block & (ptrs - 1);
188                 final = ptrs;
189         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
190                 offsets[n++] = EXT2_TIND_BLOCK;
191                 offsets[n++] = i_block >> (ptrs_bits * 2);
192                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
193                 offsets[n++] = i_block & (ptrs - 1);
194                 final = ptrs;
195         } else {
196                 ext2_msg(inode->i_sb, KERN_WARNING,
197                         "warning: %s: block is too big", __func__);
198         }
199         if (boundary)
200                 *boundary = final - 1 - (i_block & (ptrs - 1));
201 
202         return n;
203 }
204 
205 /**
206  *      ext2_get_branch - read the chain of indirect blocks leading to data
207  *      @inode: inode in question
208  *      @depth: depth of the chain (1 - direct pointer, etc.)
209  *      @offsets: offsets of pointers in inode/indirect blocks
210  *      @chain: place to store the result
211  *      @err: here we store the error value
212  *
213  *      Function fills the array of triples <key, p, bh> and returns %NULL
214  *      if everything went OK or the pointer to the last filled triple
215  *      (incomplete one) otherwise. Upon the return chain[i].key contains
216  *      the number of (i+1)-th block in the chain (as it is stored in memory,
217  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
218  *      number (it points into struct inode for i==0 and into the bh->b_data
219  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
220  *      block for i>0 and NULL for i==0. In other words, it holds the block
221  *      numbers of the chain, addresses they were taken from (and where we can
222  *      verify that chain did not change) and buffer_heads hosting these
223  *      numbers.
224  *
225  *      Function stops when it stumbles upon zero pointer (absent block)
226  *              (pointer to last triple returned, *@err == 0)
227  *      or when it gets an IO error reading an indirect block
228  *              (ditto, *@err == -EIO)
229  *      or when it notices that chain had been changed while it was reading
230  *              (ditto, *@err == -EAGAIN)
231  *      or when it reads all @depth-1 indirect blocks successfully and finds
232  *      the whole chain, all way to the data (returns %NULL, *err == 0).
233  */
234 static Indirect *ext2_get_branch(struct inode *inode,
235                                  int depth,
236                                  int *offsets,
237                                  Indirect chain[4],
238                                  int *err)
239 {
240         struct super_block *sb = inode->i_sb;
241         Indirect *p = chain;
242         struct buffer_head *bh;
243 
244         *err = 0;
245         /* i_data is not going away, no lock needed */
246         add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
247         if (!p->key)
248                 goto no_block;
249         while (--depth) {
250                 bh = sb_bread(sb, le32_to_cpu(p->key));
251                 if (!bh)
252                         goto failure;
253                 read_lock(&EXT2_I(inode)->i_meta_lock);
254                 if (!verify_chain(chain, p))
255                         goto changed;
256                 add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
257                 read_unlock(&EXT2_I(inode)->i_meta_lock);
258                 if (!p->key)
259                         goto no_block;
260         }
261         return NULL;
262 
263 changed:
264         read_unlock(&EXT2_I(inode)->i_meta_lock);
265         brelse(bh);
266         *err = -EAGAIN;
267         goto no_block;
268 failure:
269         *err = -EIO;
270 no_block:
271         return p;
272 }
273 
274 /**
275  *      ext2_find_near - find a place for allocation with sufficient locality
276  *      @inode: owner
277  *      @ind: descriptor of indirect block.
278  *
279  *      This function returns the preferred place for block allocation.
280  *      It is used when heuristic for sequential allocation fails.
281  *      Rules are:
282  *        + if there is a block to the left of our position - allocate near it.
283  *        + if pointer will live in indirect block - allocate near that block.
284  *        + if pointer will live in inode - allocate in the same cylinder group.
285  *
286  * In the latter case we colour the starting block by the callers PID to
287  * prevent it from clashing with concurrent allocations for a different inode
288  * in the same block group.   The PID is used here so that functionally related
289  * files will be close-by on-disk.
290  *
291  *      Caller must make sure that @ind is valid and will stay that way.
292  */
293 
294 static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
295 {
296         struct ext2_inode_info *ei = EXT2_I(inode);
297         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
298         __le32 *p;
299         ext2_fsblk_t bg_start;
300         ext2_fsblk_t colour;
301 
302         /* Try to find previous block */
303         for (p = ind->p - 1; p >= start; p--)
304                 if (*p)
305                         return le32_to_cpu(*p);
306 
307         /* No such thing, so let's try location of indirect block */
308         if (ind->bh)
309                 return ind->bh->b_blocknr;
310 
311         /*
312          * It is going to be referred from inode itself? OK, just put it into
313          * the same cylinder group then.
314          */
315         bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
316         colour = (current->pid % 16) *
317                         (EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
318         return bg_start + colour;
319 }
320 
321 /**
322  *      ext2_find_goal - find a preferred place for allocation.
323  *      @inode: owner
324  *      @block:  block we want
325  *      @partial: pointer to the last triple within a chain
326  *
327  *      Returns preferred place for a block (the goal).
328  */
329 
330 static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,
331                                           Indirect *partial)
332 {
333         struct ext2_block_alloc_info *block_i;
334 
335         block_i = EXT2_I(inode)->i_block_alloc_info;
336 
337         /*
338          * try the heuristic for sequential allocation,
339          * failing that at least try to get decent locality.
340          */
341         if (block_i && (block == block_i->last_alloc_logical_block + 1)
342                 && (block_i->last_alloc_physical_block != 0)) {
343                 return block_i->last_alloc_physical_block + 1;
344         }
345 
346         return ext2_find_near(inode, partial);
347 }
348 
349 /**
350  *      ext2_blks_to_allocate: Look up the block map and count the number
351  *      of direct blocks need to be allocated for the given branch.
352  *
353  *      @branch: chain of indirect blocks
354  *      @k: number of blocks need for indirect blocks
355  *      @blks: number of data blocks to be mapped.
356  *      @blocks_to_boundary:  the offset in the indirect block
357  *
358  *      return the total number of blocks to be allocate, including the
359  *      direct and indirect blocks.
360  */
361 static int
362 ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
363                 int blocks_to_boundary)
364 {
365         unsigned long count = 0;
366 
367         /*
368          * Simple case, [t,d]Indirect block(s) has not allocated yet
369          * then it's clear blocks on that path have not allocated
370          */
371         if (k > 0) {
372                 /* right now don't hanel cross boundary allocation */
373                 if (blks < blocks_to_boundary + 1)
374                         count += blks;
375                 else
376                         count += blocks_to_boundary + 1;
377                 return count;
378         }
379 
380         count++;
381         while (count < blks && count <= blocks_to_boundary
382                 && le32_to_cpu(*(branch[0].p + count)) == 0) {
383                 count++;
384         }
385         return count;
386 }
387 
388 /**
389  *      ext2_alloc_blocks: multiple allocate blocks needed for a branch
390  *      @indirect_blks: the number of blocks need to allocate for indirect
391  *                      blocks
392  *
393  *      @new_blocks: on return it will store the new block numbers for
394  *      the indirect blocks(if needed) and the first direct block,
395  *      @blks:  on return it will store the total number of allocated
396  *              direct blocks
397  */
398 static int ext2_alloc_blocks(struct inode *inode,
399                         ext2_fsblk_t goal, int indirect_blks, int blks,
400                         ext2_fsblk_t new_blocks[4], int *err)
401 {
402         int target, i;
403         unsigned long count = 0;
404         int index = 0;
405         ext2_fsblk_t current_block = 0;
406         int ret = 0;
407 
408         /*
409          * Here we try to allocate the requested multiple blocks at once,
410          * on a best-effort basis.
411          * To build a branch, we should allocate blocks for
412          * the indirect blocks(if not allocated yet), and at least
413          * the first direct block of this branch.  That's the
414          * minimum number of blocks need to allocate(required)
415          */
416         target = blks + indirect_blks;
417 
418         while (1) {
419                 count = target;
420                 /* allocating blocks for indirect blocks and direct blocks */
421                 current_block = ext2_new_blocks(inode,goal,&count,err);
422                 if (*err)
423                         goto failed_out;
424 
425                 target -= count;
426                 /* allocate blocks for indirect blocks */
427                 while (index < indirect_blks && count) {
428                         new_blocks[index++] = current_block++;
429                         count--;
430                 }
431 
432                 if (count > 0)
433                         break;
434         }
435 
436         /* save the new block number for the first direct block */
437         new_blocks[index] = current_block;
438 
439         /* total number of blocks allocated for direct blocks */
440         ret = count;
441         *err = 0;
442         return ret;
443 failed_out:
444         for (i = 0; i <index; i++)
445                 ext2_free_blocks(inode, new_blocks[i], 1);
446         if (index)
447                 mark_inode_dirty(inode);
448         return ret;
449 }
450 
451 /**
452  *      ext2_alloc_branch - allocate and set up a chain of blocks.
453  *      @inode: owner
454  *      @num: depth of the chain (number of blocks to allocate)
455  *      @offsets: offsets (in the blocks) to store the pointers to next.
456  *      @branch: place to store the chain in.
457  *
458  *      This function allocates @num blocks, zeroes out all but the last one,
459  *      links them into chain and (if we are synchronous) writes them to disk.
460  *      In other words, it prepares a branch that can be spliced onto the
461  *      inode. It stores the information about that chain in the branch[], in
462  *      the same format as ext2_get_branch() would do. We are calling it after
463  *      we had read the existing part of chain and partial points to the last
464  *      triple of that (one with zero ->key). Upon the exit we have the same
465  *      picture as after the successful ext2_get_block(), except that in one
466  *      place chain is disconnected - *branch->p is still zero (we did not
467  *      set the last link), but branch->key contains the number that should
468  *      be placed into *branch->p to fill that gap.
469  *
470  *      If allocation fails we free all blocks we've allocated (and forget
471  *      their buffer_heads) and return the error value the from failed
472  *      ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
473  *      as described above and return 0.
474  */
475 
476 static int ext2_alloc_branch(struct inode *inode,
477                         int indirect_blks, int *blks, ext2_fsblk_t goal,
478                         int *offsets, Indirect *branch)
479 {
480         int blocksize = inode->i_sb->s_blocksize;
481         int i, n = 0;
482         int err = 0;
483         struct buffer_head *bh;
484         int num;
485         ext2_fsblk_t new_blocks[4];
486         ext2_fsblk_t current_block;
487 
488         num = ext2_alloc_blocks(inode, goal, indirect_blks,
489                                 *blks, new_blocks, &err);
490         if (err)
491                 return err;
492 
493         branch[0].key = cpu_to_le32(new_blocks[0]);
494         /*
495          * metadata blocks and data blocks are allocated.
496          */
497         for (n = 1; n <= indirect_blks;  n++) {
498                 /*
499                  * Get buffer_head for parent block, zero it out
500                  * and set the pointer to new one, then send
501                  * parent to disk.
502                  */
503                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
504                 if (unlikely(!bh)) {
505                         err = -ENOMEM;
506                         goto failed;
507                 }
508                 branch[n].bh = bh;
509                 lock_buffer(bh);
510                 memset(bh->b_data, 0, blocksize);
511                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
512                 branch[n].key = cpu_to_le32(new_blocks[n]);
513                 *branch[n].p = branch[n].key;
514                 if ( n == indirect_blks) {
515                         current_block = new_blocks[n];
516                         /*
517                          * End of chain, update the last new metablock of
518                          * the chain to point to the new allocated
519                          * data blocks numbers
520                          */
521                         for (i=1; i < num; i++)
522                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
523                 }
524                 set_buffer_uptodate(bh);
525                 unlock_buffer(bh);
526                 mark_buffer_dirty_inode(bh, inode);
527                 /* We used to sync bh here if IS_SYNC(inode).
528                  * But we now rely upon generic_write_sync()
529                  * and b_inode_buffers.  But not for directories.
530                  */
531                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
532                         sync_dirty_buffer(bh);
533         }
534         *blks = num;
535         return err;
536 
537 failed:
538         for (i = 1; i < n; i++)
539                 bforget(branch[i].bh);
540         for (i = 0; i < indirect_blks; i++)
541                 ext2_free_blocks(inode, new_blocks[i], 1);
542         ext2_free_blocks(inode, new_blocks[i], num);
543         return err;
544 }
545 
546 /**
547  * ext2_splice_branch - splice the allocated branch onto inode.
548  * @inode: owner
549  * @block: (logical) number of block we are adding
550  * @where: location of missing link
551  * @num:   number of indirect blocks we are adding
552  * @blks:  number of direct blocks we are adding
553  *
554  * This function fills the missing link and does all housekeeping needed in
555  * inode (->i_blocks, etc.). In case of success we end up with the full
556  * chain to new block and return 0.
557  */
558 static void ext2_splice_branch(struct inode *inode,
559                         long block, Indirect *where, int num, int blks)
560 {
561         int i;
562         struct ext2_block_alloc_info *block_i;
563         ext2_fsblk_t current_block;
564 
565         block_i = EXT2_I(inode)->i_block_alloc_info;
566 
567         /* XXX LOCKING probably should have i_meta_lock ?*/
568         /* That's it */
569 
570         *where->p = where->key;
571 
572         /*
573          * Update the host buffer_head or inode to point to more just allocated
574          * direct blocks blocks
575          */
576         if (num == 0 && blks > 1) {
577                 current_block = le32_to_cpu(where->key) + 1;
578                 for (i = 1; i < blks; i++)
579                         *(where->p + i ) = cpu_to_le32(current_block++);
580         }
581 
582         /*
583          * update the most recently allocated logical & physical block
584          * in i_block_alloc_info, to assist find the proper goal block for next
585          * allocation
586          */
587         if (block_i) {
588                 block_i->last_alloc_logical_block = block + blks - 1;
589                 block_i->last_alloc_physical_block =
590                                 le32_to_cpu(where[num].key) + blks - 1;
591         }
592 
593         /* We are done with atomic stuff, now do the rest of housekeeping */
594 
595         /* had we spliced it onto indirect block? */
596         if (where->bh)
597                 mark_buffer_dirty_inode(where->bh, inode);
598 
599         inode->i_ctime = current_time(inode);
600         mark_inode_dirty(inode);
601 }
602 
603 /*
604  * Allocation strategy is simple: if we have to allocate something, we will
605  * have to go the whole way to leaf. So let's do it before attaching anything
606  * to tree, set linkage between the newborn blocks, write them if sync is
607  * required, recheck the path, free and repeat if check fails, otherwise
608  * set the last missing link (that will protect us from any truncate-generated
609  * removals - all blocks on the path are immune now) and possibly force the
610  * write on the parent block.
611  * That has a nice additional property: no special recovery from the failed
612  * allocations is needed - we simply release blocks and do not touch anything
613  * reachable from inode.
614  *
615  * `handle' can be NULL if create == 0.
616  *
617  * return > 0, # of blocks mapped or allocated.
618  * return = 0, if plain lookup failed.
619  * return < 0, error case.
620  */
621 static int ext2_get_blocks(struct inode *inode,
622                            sector_t iblock, unsigned long maxblocks,
623                            u32 *bno, bool *new, bool *boundary,
624                            int create)
625 {
626         int err;
627         int offsets[4];
628         Indirect chain[4];
629         Indirect *partial;
630         ext2_fsblk_t goal;
631         int indirect_blks;
632         int blocks_to_boundary = 0;
633         int depth;
634         struct ext2_inode_info *ei = EXT2_I(inode);
635         int count = 0;
636         ext2_fsblk_t first_block = 0;
637 
638         BUG_ON(maxblocks == 0);
639 
640         depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
641 
642         if (depth == 0)
643                 return -EIO;
644 
645         partial = ext2_get_branch(inode, depth, offsets, chain, &err);
646         /* Simplest case - block found, no allocation needed */
647         if (!partial) {
648                 first_block = le32_to_cpu(chain[depth - 1].key);
649                 count++;
650                 /*map more blocks*/
651                 while (count < maxblocks && count <= blocks_to_boundary) {
652                         ext2_fsblk_t blk;
653 
654                         if (!verify_chain(chain, chain + depth - 1)) {
655                                 /*
656                                  * Indirect block might be removed by
657                                  * truncate while we were reading it.
658                                  * Handling of that case: forget what we've
659                                  * got now, go to reread.
660                                  */
661                                 err = -EAGAIN;
662                                 count = 0;
663                                 partial = chain + depth - 1;
664                                 break;
665                         }
666                         blk = le32_to_cpu(*(chain[depth-1].p + count));
667                         if (blk == first_block + count)
668                                 count++;
669                         else
670                                 break;
671                 }
672                 if (err != -EAGAIN)
673                         goto got_it;
674         }
675 
676         /* Next simple case - plain lookup or failed read of indirect block */
677         if (!create || err == -EIO)
678                 goto cleanup;
679 
680         mutex_lock(&ei->truncate_mutex);
681         /*
682          * If the indirect block is missing while we are reading
683          * the chain(ext2_get_branch() returns -EAGAIN err), or
684          * if the chain has been changed after we grab the semaphore,
685          * (either because another process truncated this branch, or
686          * another get_block allocated this branch) re-grab the chain to see if
687          * the request block has been allocated or not.
688          *
689          * Since we already block the truncate/other get_block
690          * at this point, we will have the current copy of the chain when we
691          * splice the branch into the tree.
692          */
693         if (err == -EAGAIN || !verify_chain(chain, partial)) {
694                 while (partial > chain) {
695                         brelse(partial->bh);
696                         partial--;
697                 }
698                 partial = ext2_get_branch(inode, depth, offsets, chain, &err);
699                 if (!partial) {
700                         count++;
701                         mutex_unlock(&ei->truncate_mutex);
702                         if (err)
703                                 goto cleanup;
704                         goto got_it;
705                 }
706         }
707 
708         /*
709          * Okay, we need to do block allocation.  Lazily initialize the block
710          * allocation info here if necessary
711         */
712         if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
713                 ext2_init_block_alloc_info(inode);
714 
715         goal = ext2_find_goal(inode, iblock, partial);
716 
717         /* the number of blocks need to allocate for [d,t]indirect blocks */
718         indirect_blks = (chain + depth) - partial - 1;
719         /*
720          * Next look up the indirect map to count the totoal number of
721          * direct blocks to allocate for this branch.
722          */
723         count = ext2_blks_to_allocate(partial, indirect_blks,
724                                         maxblocks, blocks_to_boundary);
725         /*
726          * XXX ???? Block out ext2_truncate while we alter the tree
727          */
728         err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
729                                 offsets + (partial - chain), partial);
730 
731         if (err) {
732                 mutex_unlock(&ei->truncate_mutex);
733                 goto cleanup;
734         }
735 
736         if (IS_DAX(inode)) {
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                 clean_bdev_aliases(inode->i_sb->s_bdev,
742                                    le32_to_cpu(chain[depth-1].key),
743                                    count);
744                 /*
745                  * block must be initialised before we put it in the tree
746                  * so that it's not found by another thread before it's
747                  * initialised
748                  */
749                 err = sb_issue_zeroout(inode->i_sb,
750                                 le32_to_cpu(chain[depth-1].key), count,
751                                 GFP_NOFS);
752                 if (err) {
753                         mutex_unlock(&ei->truncate_mutex);
754                         goto cleanup;
755                 }
756         }
757         *new = true;
758 
759         ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
760         mutex_unlock(&ei->truncate_mutex);
761 got_it:
762         if (count > blocks_to_boundary)
763                 *boundary = true;
764         err = count;
765         /* Clean up and exit */
766         partial = chain + depth - 1;    /* the whole chain */
767 cleanup:
768         while (partial > chain) {
769                 brelse(partial->bh);
770                 partial--;
771         }
772         if (err > 0)
773                 *bno = le32_to_cpu(chain[depth-1].key);
774         return err;
775 }
776 
777 int ext2_get_block(struct inode *inode, sector_t iblock,
778                 struct buffer_head *bh_result, int create)
779 {
780         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
781         bool new = false, boundary = false;
782         u32 bno;
783         int ret;
784 
785         ret = ext2_get_blocks(inode, iblock, max_blocks, &bno, &new, &boundary,
786                         create);
787         if (ret <= 0)
788                 return ret;
789 
790         map_bh(bh_result, inode->i_sb, bno);
791         bh_result->b_size = (ret << inode->i_blkbits);
792         if (new)
793                 set_buffer_new(bh_result);
794         if (boundary)
795                 set_buffer_boundary(bh_result);
796         return 0;
797 
798 }
799 
800 #ifdef CONFIG_FS_DAX
801 static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
802                 unsigned flags, struct iomap *iomap)
803 {
804         unsigned int blkbits = inode->i_blkbits;
805         unsigned long first_block = offset >> blkbits;
806         unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
807         struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
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         iomap->dax_dev = sbi->s_daxdev;
821 
822         if (ret == 0) {
823                 iomap->type = IOMAP_HOLE;
824                 iomap->addr = IOMAP_NULL_ADDR;
825                 iomap->length = 1 << blkbits;
826         } else {
827                 iomap->type = IOMAP_MAPPED;
828                 iomap->addr = (u64)bno << blkbits;
829                 iomap->length = (u64)ret << blkbits;
830                 iomap->flags |= IOMAP_F_MERGED;
831         }
832 
833         if (new)
834                 iomap->flags |= IOMAP_F_NEW;
835         return 0;
836 }
837 
838 static int
839 ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
840                 ssize_t written, unsigned flags, struct iomap *iomap)
841 {
842         if (iomap->type == IOMAP_MAPPED &&
843             written < length &&
844             (flags & IOMAP_WRITE))
845                 ext2_write_failed(inode->i_mapping, offset + length);
846         return 0;
847 }
848 
849 const struct iomap_ops ext2_iomap_ops = {
850         .iomap_begin            = ext2_iomap_begin,
851         .iomap_end              = ext2_iomap_end,
852 };
853 #else
854 /* Define empty ops for !CONFIG_FS_DAX case to avoid ugly ifdefs */
855 const struct iomap_ops ext2_iomap_ops;
856 #endif /* CONFIG_FS_DAX */
857 
858 int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
859                 u64 start, u64 len)
860 {
861         return generic_block_fiemap(inode, fieinfo, start, len,
862                                     ext2_get_block);
863 }
864 
865 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
866 {
867         return block_write_full_page(page, ext2_get_block, wbc);
868 }
869 
870 static int ext2_readpage(struct file *file, struct page *page)
871 {
872         return mpage_readpage(page, ext2_get_block);
873 }
874 
875 static int
876 ext2_readpages(struct file *file, struct address_space *mapping,
877                 struct list_head *pages, unsigned nr_pages)
878 {
879         return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
880 }
881 
882 static int
883 ext2_write_begin(struct file *file, struct address_space *mapping,
884                 loff_t pos, unsigned len, unsigned flags,
885                 struct page **pagep, void **fsdata)
886 {
887         int ret;
888 
889         ret = block_write_begin(mapping, pos, len, flags, pagep,
890                                 ext2_get_block);
891         if (ret < 0)
892                 ext2_write_failed(mapping, pos + len);
893         return ret;
894 }
895 
896 static int ext2_write_end(struct file *file, struct address_space *mapping,
897                         loff_t pos, unsigned len, unsigned copied,
898                         struct page *page, void *fsdata)
899 {
900         int ret;
901 
902         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
903         if (ret < len)
904                 ext2_write_failed(mapping, pos + len);
905         return ret;
906 }
907 
908 static int
909 ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
910                 loff_t pos, unsigned len, unsigned flags,
911                 struct page **pagep, void **fsdata)
912 {
913         int ret;
914 
915         ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
916                                ext2_get_block);
917         if (ret < 0)
918                 ext2_write_failed(mapping, pos + len);
919         return ret;
920 }
921 
922 static int ext2_nobh_writepage(struct page *page,
923                         struct writeback_control *wbc)
924 {
925         return nobh_writepage(page, ext2_get_block, wbc);
926 }
927 
928 static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
929 {
930         return generic_block_bmap(mapping,block,ext2_get_block);
931 }
932 
933 static ssize_t
934 ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
935 {
936         struct file *file = iocb->ki_filp;
937         struct address_space *mapping = file->f_mapping;
938         struct inode *inode = mapping->host;
939         size_t count = iov_iter_count(iter);
940         loff_t offset = iocb->ki_pos;
941         ssize_t ret;
942 
943         ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
944         if (ret < 0 && iov_iter_rw(iter) == WRITE)
945                 ext2_write_failed(mapping, offset + count);
946         return ret;
947 }
948 
949 static int
950 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
951 {
952         return mpage_writepages(mapping, wbc, ext2_get_block);
953 }
954 
955 static int
956 ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
957 {
958         return dax_writeback_mapping_range(mapping,
959                         mapping->host->i_sb->s_bdev, wbc);
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 static const struct address_space_operations ext2_dax_aops = {
990         .writepages             = ext2_dax_writepages,
991         .direct_IO              = noop_direct_IO,
992         .set_page_dirty         = noop_set_page_dirty,
993         .invalidatepage         = noop_invalidatepage,
994 };
995 
996 /*
997  * Probably it should be a library function... search for first non-zero word
998  * or memcmp with zero_page, whatever is better for particular architecture.
999  * Linus?
1000  */
1001 static inline int all_zeroes(__le32 *p, __le32 *q)
1002 {
1003         while (p < q)
1004                 if (*p++)
1005                         return 0;
1006         return 1;
1007 }
1008 
1009 /**
1010  *      ext2_find_shared - find the indirect blocks for partial truncation.
1011  *      @inode:   inode in question
1012  *      @depth:   depth of the affected branch
1013  *      @offsets: offsets of pointers in that branch (see ext2_block_to_path)
1014  *      @chain:   place to store the pointers to partial indirect blocks
1015  *      @top:     place to the (detached) top of branch
1016  *
1017  *      This is a helper function used by ext2_truncate().
1018  *
1019  *      When we do truncate() we may have to clean the ends of several indirect
1020  *      blocks but leave the blocks themselves alive. Block is partially
1021  *      truncated if some data below the new i_size is referred from it (and
1022  *      it is on the path to the first completely truncated data block, indeed).
1023  *      We have to free the top of that path along with everything to the right
1024  *      of the path. Since no allocation past the truncation point is possible
1025  *      until ext2_truncate() finishes, we may safely do the latter, but top
1026  *      of branch may require special attention - pageout below the truncation
1027  *      point might try to populate it.
1028  *
1029  *      We atomically detach the top of branch from the tree, store the block
1030  *      number of its root in *@top, pointers to buffer_heads of partially
1031  *      truncated blocks - in @chain[].bh and pointers to their last elements
1032  *      that should not be removed - in @chain[].p. Return value is the pointer
1033  *      to last filled element of @chain.
1034  *
1035  *      The work left to caller to do the actual freeing of subtrees:
1036  *              a) free the subtree starting from *@top
1037  *              b) free the subtrees whose roots are stored in
1038  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
1039  *              c) free the subtrees growing from the inode past the @chain[0].p
1040  *                      (no partially truncated stuff there).
1041  */
1042 
1043 static Indirect *ext2_find_shared(struct inode *inode,
1044                                 int depth,
1045                                 int offsets[4],
1046                                 Indirect chain[4],
1047                                 __le32 *top)
1048 {
1049         Indirect *partial, *p;
1050         int k, err;
1051 
1052         *top = 0;
1053         for (k = depth; k > 1 && !offsets[k-1]; k--)
1054                 ;
1055         partial = ext2_get_branch(inode, k, offsets, chain, &err);
1056         if (!partial)
1057                 partial = chain + k-1;
1058         /*
1059          * If the branch acquired continuation since we've looked at it -
1060          * fine, it should all survive and (new) top doesn't belong to us.
1061          */
1062         write_lock(&EXT2_I(inode)->i_meta_lock);
1063         if (!partial->key && *partial->p) {
1064                 write_unlock(&EXT2_I(inode)->i_meta_lock);
1065                 goto no_top;
1066         }
1067         for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
1068                 ;
1069         /*
1070          * OK, we've found the last block that must survive. The rest of our
1071          * branch should be detached before unlocking. However, if that rest
1072          * of branch is all ours and does not grow immediately from the inode
1073          * it's easier to cheat and just decrement partial->p.
1074          */
1075         if (p == chain + k - 1 && p > chain) {
1076                 p->p--;
1077         } else {
1078                 *top = *p->p;
1079                 *p->p = 0;
1080         }
1081         write_unlock(&EXT2_I(inode)->i_meta_lock);
1082 
1083         while(partial > p)
1084         {
1085                 brelse(partial->bh);
1086                 partial--;
1087         }
1088 no_top:
1089         return partial;
1090 }
1091 
1092 /**
1093  *      ext2_free_data - free a list of data blocks
1094  *      @inode: inode we are dealing with
1095  *      @p:     array of block numbers
1096  *      @q:     points immediately past the end of array
1097  *
1098  *      We are freeing all blocks referred from that array (numbers are
1099  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1100  *      appropriately.
1101  */
1102 static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
1103 {
1104         unsigned long block_to_free = 0, count = 0;
1105         unsigned long nr;
1106 
1107         for ( ; p < q ; p++) {
1108                 nr = le32_to_cpu(*p);
1109                 if (nr) {
1110                         *p = 0;
1111                         /* accumulate blocks to free if they're contiguous */
1112                         if (count == 0)
1113                                 goto free_this;
1114                         else if (block_to_free == nr - count)
1115                                 count++;
1116                         else {
1117                                 ext2_free_blocks (inode, block_to_free, count);
1118                                 mark_inode_dirty(inode);
1119                         free_this:
1120                                 block_to_free = nr;
1121                                 count = 1;
1122                         }
1123                 }
1124         }
1125         if (count > 0) {
1126                 ext2_free_blocks (inode, block_to_free, count);
1127                 mark_inode_dirty(inode);
1128         }
1129 }
1130 
1131 /**
1132  *      ext2_free_branches - free an array of branches
1133  *      @inode: inode we are dealing with
1134  *      @p:     array of block numbers
1135  *      @q:     pointer immediately past the end of array
1136  *      @depth: depth of the branches to free
1137  *
1138  *      We are freeing all blocks referred from these branches (numbers are
1139  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1140  *      appropriately.
1141  */
1142 static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
1143 {
1144         struct buffer_head * bh;
1145         unsigned long nr;
1146 
1147         if (depth--) {
1148                 int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1149                 for ( ; p < q ; p++) {
1150                         nr = le32_to_cpu(*p);
1151                         if (!nr)
1152                                 continue;
1153                         *p = 0;
1154                         bh = sb_bread(inode->i_sb, nr);
1155                         /*
1156                          * A read failure? Report error and clear slot
1157                          * (should be rare).
1158                          */ 
1159                         if (!bh) {
1160                                 ext2_error(inode->i_sb, "ext2_free_branches",
1161                                         "Read failure, inode=%ld, block=%ld",
1162                                         inode->i_ino, nr);
1163                                 continue;
1164                         }
1165                         ext2_free_branches(inode,
1166                                            (__le32*)bh->b_data,
1167                                            (__le32*)bh->b_data + addr_per_block,
1168                                            depth);
1169                         bforget(bh);
1170                         ext2_free_blocks(inode, nr, 1);
1171                         mark_inode_dirty(inode);
1172                 }
1173         } else
1174                 ext2_free_data(inode, p, q);
1175 }
1176 
1177 /* dax_sem must be held when calling this function */
1178 static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
1179 {
1180         __le32 *i_data = EXT2_I(inode)->i_data;
1181         struct ext2_inode_info *ei = EXT2_I(inode);
1182         int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1183         int offsets[4];
1184         Indirect chain[4];
1185         Indirect *partial;
1186         __le32 nr = 0;
1187         int n;
1188         long iblock;
1189         unsigned blocksize;
1190         blocksize = inode->i_sb->s_blocksize;
1191         iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
1192 
1193 #ifdef CONFIG_FS_DAX
1194         WARN_ON(!rwsem_is_locked(&ei->dax_sem));
1195 #endif
1196 
1197         n = ext2_block_to_path(inode, iblock, offsets, NULL);
1198         if (n == 0)
1199                 return;
1200 
1201         /*
1202          * From here we block out all ext2_get_block() callers who want to
1203          * modify the block allocation tree.
1204          */
1205         mutex_lock(&ei->truncate_mutex);
1206 
1207         if (n == 1) {
1208                 ext2_free_data(inode, i_data+offsets[0],
1209                                         i_data + EXT2_NDIR_BLOCKS);
1210                 goto do_indirects;
1211         }
1212 
1213         partial = ext2_find_shared(inode, n, offsets, chain, &nr);
1214         /* Kill the top of shared branch (already detached) */
1215         if (nr) {
1216                 if (partial == chain)
1217                         mark_inode_dirty(inode);
1218                 else
1219                         mark_buffer_dirty_inode(partial->bh, inode);
1220                 ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
1221         }
1222         /* Clear the ends of indirect blocks on the shared branch */
1223         while (partial > chain) {
1224                 ext2_free_branches(inode,
1225                                    partial->p + 1,
1226                                    (__le32*)partial->bh->b_data+addr_per_block,
1227                                    (chain+n-1) - partial);
1228                 mark_buffer_dirty_inode(partial->bh, inode);
1229                 brelse (partial->bh);
1230                 partial--;
1231         }
1232 do_indirects:
1233         /* Kill the remaining (whole) subtrees */
1234         switch (offsets[0]) {
1235                 default:
1236                         nr = i_data[EXT2_IND_BLOCK];
1237                         if (nr) {
1238                                 i_data[EXT2_IND_BLOCK] = 0;
1239                                 mark_inode_dirty(inode);
1240                                 ext2_free_branches(inode, &nr, &nr+1, 1);
1241                         }
1242                 case EXT2_IND_BLOCK:
1243                         nr = i_data[EXT2_DIND_BLOCK];
1244                         if (nr) {
1245                                 i_data[EXT2_DIND_BLOCK] = 0;
1246                                 mark_inode_dirty(inode);
1247                                 ext2_free_branches(inode, &nr, &nr+1, 2);
1248                         }
1249                 case EXT2_DIND_BLOCK:
1250                         nr = i_data[EXT2_TIND_BLOCK];
1251                         if (nr) {
1252                                 i_data[EXT2_TIND_BLOCK] = 0;
1253                                 mark_inode_dirty(inode);
1254                                 ext2_free_branches(inode, &nr, &nr+1, 3);
1255                         }
1256                 case EXT2_TIND_BLOCK:
1257                         ;
1258         }
1259 
1260         ext2_discard_reservation(inode);
1261 
1262         mutex_unlock(&ei->truncate_mutex);
1263 }
1264 
1265 static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
1266 {
1267         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1268             S_ISLNK(inode->i_mode)))
1269                 return;
1270         if (ext2_inode_is_fast_symlink(inode))
1271                 return;
1272 
1273         dax_sem_down_write(EXT2_I(inode));
1274         __ext2_truncate_blocks(inode, offset);
1275         dax_sem_up_write(EXT2_I(inode));
1276 }
1277 
1278 static int ext2_setsize(struct inode *inode, loff_t newsize)
1279 {
1280         int error;
1281 
1282         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1283             S_ISLNK(inode->i_mode)))
1284                 return -EINVAL;
1285         if (ext2_inode_is_fast_symlink(inode))
1286                 return -EINVAL;
1287         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1288                 return -EPERM;
1289 
1290         inode_dio_wait(inode);
1291 
1292         if (IS_DAX(inode)) {
1293                 error = iomap_zero_range(inode, newsize,
1294                                          PAGE_ALIGN(newsize) - newsize, NULL,
1295                                          &ext2_iomap_ops);
1296         } else if (test_opt(inode->i_sb, NOBH))
1297                 error = nobh_truncate_page(inode->i_mapping,
1298                                 newsize, ext2_get_block);
1299         else
1300                 error = block_truncate_page(inode->i_mapping,
1301                                 newsize, ext2_get_block);
1302         if (error)
1303                 return error;
1304 
1305         dax_sem_down_write(EXT2_I(inode));
1306         truncate_setsize(inode, newsize);
1307         __ext2_truncate_blocks(inode, newsize);
1308         dax_sem_up_write(EXT2_I(inode));
1309 
1310         inode->i_mtime = inode->i_ctime = current_time(inode);
1311         if (inode_needs_sync(inode)) {
1312                 sync_mapping_buffers(inode->i_mapping);
1313                 sync_inode_metadata(inode, 1);
1314         } else {
1315                 mark_inode_dirty(inode);
1316         }
1317 
1318         return 0;
1319 }
1320 
1321 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
1322                                         struct buffer_head **p)
1323 {
1324         struct buffer_head * bh;
1325         unsigned long block_group;
1326         unsigned long block;
1327         unsigned long offset;
1328         struct ext2_group_desc * gdp;
1329 
1330         *p = NULL;
1331         if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
1332             ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
1333                 goto Einval;
1334 
1335         block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
1336         gdp = ext2_get_group_desc(sb, block_group, NULL);
1337         if (!gdp)
1338                 goto Egdp;
1339         /*
1340          * Figure out the offset within the block group inode table
1341          */
1342         offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
1343         block = le32_to_cpu(gdp->bg_inode_table) +
1344                 (offset >> EXT2_BLOCK_SIZE_BITS(sb));
1345         if (!(bh = sb_bread(sb, block)))
1346                 goto Eio;
1347 
1348         *p = bh;
1349         offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1350         return (struct ext2_inode *) (bh->b_data + offset);
1351 
1352 Einval:
1353         ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1354                    (unsigned long) ino);
1355         return ERR_PTR(-EINVAL);
1356 Eio:
1357         ext2_error(sb, "ext2_get_inode",
1358                    "unable to read inode block - inode=%lu, block=%lu",
1359                    (unsigned long) ino, block);
1360 Egdp:
1361         return ERR_PTR(-EIO);
1362 }
1363 
1364 void ext2_set_inode_flags(struct inode *inode)
1365 {
1366         unsigned int flags = EXT2_I(inode)->i_flags;
1367 
1368         inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
1369                                 S_DIRSYNC | S_DAX);
1370         if (flags & EXT2_SYNC_FL)
1371                 inode->i_flags |= S_SYNC;
1372         if (flags & EXT2_APPEND_FL)
1373                 inode->i_flags |= S_APPEND;
1374         if (flags & EXT2_IMMUTABLE_FL)
1375                 inode->i_flags |= S_IMMUTABLE;
1376         if (flags & EXT2_NOATIME_FL)
1377                 inode->i_flags |= S_NOATIME;
1378         if (flags & EXT2_DIRSYNC_FL)
1379                 inode->i_flags |= S_DIRSYNC;
1380         if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
1381                 inode->i_flags |= S_DAX;
1382 }
1383 
1384 void ext2_set_file_ops(struct inode *inode)
1385 {
1386         inode->i_op = &ext2_file_inode_operations;
1387         inode->i_fop = &ext2_file_operations;
1388         if (IS_DAX(inode))
1389                 inode->i_mapping->a_ops = &ext2_dax_aops;
1390         else if (test_opt(inode->i_sb, NOBH))
1391                 inode->i_mapping->a_ops = &ext2_nobh_aops;
1392         else
1393                 inode->i_mapping->a_ops = &ext2_aops;
1394 }
1395 
1396 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
1397 {
1398         struct ext2_inode_info *ei;
1399         struct buffer_head * bh;
1400         struct ext2_inode *raw_inode;
1401         struct inode *inode;
1402         long ret = -EIO;
1403         int n;
1404         uid_t i_uid;
1405         gid_t i_gid;
1406 
1407         inode = iget_locked(sb, ino);
1408         if (!inode)
1409                 return ERR_PTR(-ENOMEM);
1410         if (!(inode->i_state & I_NEW))
1411                 return inode;
1412 
1413         ei = EXT2_I(inode);
1414         ei->i_block_alloc_info = NULL;
1415 
1416         raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1417         if (IS_ERR(raw_inode)) {
1418                 ret = PTR_ERR(raw_inode);
1419                 goto bad_inode;
1420         }
1421 
1422         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1423         i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1424         i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1425         if (!(test_opt (inode->i_sb, NO_UID32))) {
1426                 i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1427                 i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1428         }
1429         i_uid_write(inode, i_uid);
1430         i_gid_write(inode, i_gid);
1431         set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
1432         inode->i_size = le32_to_cpu(raw_inode->i_size);
1433         inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
1434         inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
1435         inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
1436         inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1437         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1438         /* We now have enough fields to check if the inode was active or not.
1439          * This is needed because nfsd might try to access dead inodes
1440          * the test is that same one that e2fsck uses
1441          * NeilBrown 1999oct15
1442          */
1443         if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1444                 /* this inode is deleted */
1445                 brelse (bh);
1446                 ret = -ESTALE;
1447                 goto bad_inode;
1448         }
1449         inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1450         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1451         ext2_set_inode_flags(inode);
1452         ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1453         ei->i_frag_no = raw_inode->i_frag;
1454         ei->i_frag_size = raw_inode->i_fsize;
1455         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1456         ei->i_dir_acl = 0;
1457 
1458         if (ei->i_file_acl &&
1459             !ext2_data_block_valid(EXT2_SB(sb), ei->i_file_acl, 1)) {
1460                 ext2_error(sb, "ext2_iget", "bad extended attribute block %u",
1461                            ei->i_file_acl);
1462                 brelse(bh);
1463                 ret = -EFSCORRUPTED;
1464                 goto bad_inode;
1465         }
1466 
1467         if (S_ISREG(inode->i_mode))
1468                 inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1469         else
1470                 ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1471         if (i_size_read(inode) < 0) {
1472                 ret = -EFSCORRUPTED;
1473                 goto bad_inode;
1474         }
1475         ei->i_dtime = 0;
1476         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1477         ei->i_state = 0;
1478         ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1479         ei->i_dir_start_lookup = 0;
1480 
1481         /*
1482          * NOTE! The in-memory inode i_data array is in little-endian order
1483          * even on big-endian machines: we do NOT byteswap the block numbers!
1484          */
1485         for (n = 0; n < EXT2_N_BLOCKS; n++)
1486                 ei->i_data[n] = raw_inode->i_block[n];
1487 
1488         if (S_ISREG(inode->i_mode)) {
1489                 ext2_set_file_ops(inode);
1490         } else if (S_ISDIR(inode->i_mode)) {
1491                 inode->i_op = &ext2_dir_inode_operations;
1492                 inode->i_fop = &ext2_dir_operations;
1493                 if (test_opt(inode->i_sb, NOBH))
1494                         inode->i_mapping->a_ops = &ext2_nobh_aops;
1495                 else
1496                         inode->i_mapping->a_ops = &ext2_aops;
1497         } else if (S_ISLNK(inode->i_mode)) {
1498                 if (ext2_inode_is_fast_symlink(inode)) {
1499                         inode->i_link = (char *)ei->i_data;
1500                         inode->i_op = &ext2_fast_symlink_inode_operations;
1501                         nd_terminate_link(ei->i_data, inode->i_size,
1502                                 sizeof(ei->i_data) - 1);
1503                 } else {
1504                         inode->i_op = &ext2_symlink_inode_operations;
1505                         inode_nohighmem(inode);
1506                         if (test_opt(inode->i_sb, NOBH))
1507                                 inode->i_mapping->a_ops = &ext2_nobh_aops;
1508                         else
1509                                 inode->i_mapping->a_ops = &ext2_aops;
1510                 }
1511         } else {
1512                 inode->i_op = &ext2_special_inode_operations;
1513                 if (raw_inode->i_block[0])
1514                         init_special_inode(inode, inode->i_mode,
1515                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1516                 else 
1517                         init_special_inode(inode, inode->i_mode,
1518                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1519         }
1520         brelse (bh);
1521         unlock_new_inode(inode);
1522         return inode;
1523         
1524 bad_inode:
1525         iget_failed(inode);
1526         return ERR_PTR(ret);
1527 }
1528 
1529 static int __ext2_write_inode(struct inode *inode, int do_sync)
1530 {
1531         struct ext2_inode_info *ei = EXT2_I(inode);
1532         struct super_block *sb = inode->i_sb;
1533         ino_t ino = inode->i_ino;
1534         uid_t uid = i_uid_read(inode);
1535         gid_t gid = i_gid_read(inode);
1536         struct buffer_head * bh;
1537         struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1538         int n;
1539         int err = 0;
1540 
1541         if (IS_ERR(raw_inode))
1542                 return -EIO;
1543 
1544         /* For fields not not tracking in the in-memory inode,
1545          * initialise them to zero for new inodes. */
1546         if (ei->i_state & EXT2_STATE_NEW)
1547                 memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1548 
1549         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1550         if (!(test_opt(sb, NO_UID32))) {
1551                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1552                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1553 /*
1554  * Fix up interoperability with old kernels. Otherwise, old inodes get
1555  * re-used with the upper 16 bits of the uid/gid intact
1556  */
1557                 if (!ei->i_dtime) {
1558                         raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1559                         raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1560                 } else {
1561                         raw_inode->i_uid_high = 0;
1562                         raw_inode->i_gid_high = 0;
1563                 }
1564         } else {
1565                 raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1566                 raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1567                 raw_inode->i_uid_high = 0;
1568                 raw_inode->i_gid_high = 0;
1569         }
1570         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1571         raw_inode->i_size = cpu_to_le32(inode->i_size);
1572         raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1573         raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1574         raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1575 
1576         raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1577         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1578         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1579         raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1580         raw_inode->i_frag = ei->i_frag_no;
1581         raw_inode->i_fsize = ei->i_frag_size;
1582         raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1583         if (!S_ISREG(inode->i_mode))
1584                 raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1585         else {
1586                 raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1587                 if (inode->i_size > 0x7fffffffULL) {
1588                         if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1589                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1590                             EXT2_SB(sb)->s_es->s_rev_level ==
1591                                         cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1592                                /* If this is the first large file
1593                                 * created, add a flag to the superblock.
1594                                 */
1595                                 spin_lock(&EXT2_SB(sb)->s_lock);
1596                                 ext2_update_dynamic_rev(sb);
1597                                 EXT2_SET_RO_COMPAT_FEATURE(sb,
1598                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1599                                 spin_unlock(&EXT2_SB(sb)->s_lock);
1600                                 ext2_sync_super(sb, EXT2_SB(sb)->s_es, 1);
1601                         }
1602                 }
1603         }
1604         
1605         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1606         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1607                 if (old_valid_dev(inode->i_rdev)) {
1608                         raw_inode->i_block[0] =
1609                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
1610                         raw_inode->i_block[1] = 0;
1611                 } else {
1612                         raw_inode->i_block[0] = 0;
1613                         raw_inode->i_block[1] =
1614                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
1615                         raw_inode->i_block[2] = 0;
1616                 }
1617         } else for (n = 0; n < EXT2_N_BLOCKS; n++)
1618                 raw_inode->i_block[n] = ei->i_data[n];
1619         mark_buffer_dirty(bh);
1620         if (do_sync) {
1621                 sync_dirty_buffer(bh);
1622                 if (buffer_req(bh) && !buffer_uptodate(bh)) {
1623                         printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1624                                 sb->s_id, (unsigned long) ino);
1625                         err = -EIO;
1626                 }
1627         }
1628         ei->i_state &= ~EXT2_STATE_NEW;
1629         brelse (bh);
1630         return err;
1631 }
1632 
1633 int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
1634 {
1635         return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
1636 }
1637 
1638 int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1639 {
1640         struct inode *inode = d_inode(dentry);
1641         int error;
1642 
1643         error = setattr_prepare(dentry, iattr);
1644         if (error)
1645                 return error;
1646 
1647         if (is_quota_modification(inode, iattr)) {
1648                 error = dquot_initialize(inode);
1649                 if (error)
1650                         return error;
1651         }
1652         if ((iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)) ||
1653             (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))) {
1654                 error = dquot_transfer(inode, iattr);
1655                 if (error)
1656                         return error;
1657         }
1658         if (iattr->ia_valid & ATTR_SIZE && iattr->ia_size != inode->i_size) {
1659                 error = ext2_setsize(inode, iattr->ia_size);
1660                 if (error)
1661                         return error;
1662         }
1663         setattr_copy(inode, iattr);
1664         if (iattr->ia_valid & ATTR_MODE)
1665                 error = posix_acl_chmod(inode, inode->i_mode);
1666         mark_inode_dirty(inode);
1667 
1668         return error;
1669 }
1670 

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