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/smp_lock.h>
26 #include <linux/time.h>
27 #include <linux/highuid.h>
28 #include <linux/pagemap.h>
29 #include <linux/quotaops.h>
30 #include <linux/module.h>
31 #include <linux/writeback.h>
32 #include <linux/buffer_head.h>
33 #include <linux/mpage.h>
34 #include "ext2.h"
35 #include "acl.h"
36
37 MODULE_AUTHOR("Remy Card and others");
38 MODULE_DESCRIPTION("Second Extended Filesystem");
39 MODULE_LICENSE("GPL");
40
41 static int ext2_update_inode(struct inode * inode, int do_sync);
42
43 /*
44 * Test whether an inode is a fast symlink.
45 */
46 static inline int ext2_inode_is_fast_symlink(struct inode *inode)
47 {
48 int ea_blocks = EXT2_I(inode)->i_file_acl ?
49 (inode->i_sb->s_blocksize >> 9) : 0;
50
51 return (S_ISLNK(inode->i_mode) &&
52 inode->i_blocks - ea_blocks == 0);
53 }
54
55 /*
56 * Called at the last iput() if i_nlink is zero.
57 */
58 void ext2_delete_inode (struct inode * inode)
59 {
60 if (is_bad_inode(inode))
61 goto no_delete;
62 EXT2_I(inode)->i_dtime = get_seconds();
63 mark_inode_dirty(inode);
64 ext2_update_inode(inode, inode_needs_sync(inode));
65
66 inode->i_size = 0;
67 if (inode->i_blocks)
68 ext2_truncate (inode);
69 ext2_free_inode (inode);
70
71 return;
72 no_delete:
73 clear_inode(inode); /* We must guarantee clearing of inode... */
74 }
75
76 void ext2_discard_prealloc (struct inode * inode)
77 {
78 #ifdef EXT2_PREALLOCATE
79 struct ext2_inode_info *ei = EXT2_I(inode);
80 write_lock(&ei->i_meta_lock);
81 if (ei->i_prealloc_count) {
82 unsigned short total = ei->i_prealloc_count;
83 unsigned long block = ei->i_prealloc_block;
84 ei->i_prealloc_count = 0;
85 ei->i_prealloc_block = 0;
86 write_unlock(&ei->i_meta_lock);
87 ext2_free_blocks (inode, block, total);
88 return;
89 } else
90 write_unlock(&ei->i_meta_lock);
91 #endif
92 }
93
94 static int ext2_alloc_block (struct inode * inode, unsigned long goal, int *err)
95 {
96 #ifdef EXT2FS_DEBUG
97 static unsigned long alloc_hits, alloc_attempts;
98 #endif
99 unsigned long result;
100
101
102 #ifdef EXT2_PREALLOCATE
103 struct ext2_inode_info *ei = EXT2_I(inode);
104 write_lock(&ei->i_meta_lock);
105 if (ei->i_prealloc_count &&
106 (goal == ei->i_prealloc_block || goal + 1 == ei->i_prealloc_block))
107 {
108 result = ei->i_prealloc_block++;
109 ei->i_prealloc_count--;
110 write_unlock(&ei->i_meta_lock);
111 ext2_debug ("preallocation hit (%lu/%lu).\n",
112 ++alloc_hits, ++alloc_attempts);
113 } else {
114 write_unlock(&ei->i_meta_lock);
115 ext2_discard_prealloc (inode);
116 ext2_debug ("preallocation miss (%lu/%lu).\n",
117 alloc_hits, ++alloc_attempts);
118 if (S_ISREG(inode->i_mode))
119 result = ext2_new_block (inode, goal,
120 &ei->i_prealloc_count,
121 &ei->i_prealloc_block, err);
122 else
123 result = ext2_new_block(inode, goal, NULL, NULL, err);
124 }
125 #else
126 result = ext2_new_block (inode, goal, 0, 0, err);
127 #endif
128 return result;
129 }
130
131 typedef struct {
132 __le32 *p;
133 __le32 key;
134 struct buffer_head *bh;
135 } Indirect;
136
137 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
138 {
139 p->key = *(p->p = v);
140 p->bh = bh;
141 }
142
143 static inline int verify_chain(Indirect *from, Indirect *to)
144 {
145 while (from <= to && from->key == *from->p)
146 from++;
147 return (from > to);
148 }
149
150 /**
151 * ext2_block_to_path - parse the block number into array of offsets
152 * @inode: inode in question (we are only interested in its superblock)
153 * @i_block: block number to be parsed
154 * @offsets: array to store the offsets in
155 * @boundary: set this non-zero if the referred-to block is likely to be
156 * followed (on disk) by an indirect block.
157 * To store the locations of file's data ext2 uses a data structure common
158 * for UNIX filesystems - tree of pointers anchored in the inode, with
159 * data blocks at leaves and indirect blocks in intermediate nodes.
160 * This function translates the block number into path in that tree -
161 * return value is the path length and @offsets[n] is the offset of
162 * pointer to (n+1)th node in the nth one. If @block is out of range
163 * (negative or too large) warning is printed and zero returned.
164 *
165 * Note: function doesn't find node addresses, so no IO is needed. All
166 * we need to know is the capacity of indirect blocks (taken from the
167 * inode->i_sb).
168 */
169
170 /*
171 * Portability note: the last comparison (check that we fit into triple
172 * indirect block) is spelled differently, because otherwise on an
173 * architecture with 32-bit longs and 8Kb pages we might get into trouble
174 * if our filesystem had 8Kb blocks. We might use long long, but that would
175 * kill us on x86. Oh, well, at least the sign propagation does not matter -
176 * i_block would have to be negative in the very beginning, so we would not
177 * get there at all.
178 */
179
180 static int ext2_block_to_path(struct inode *inode,
181 long i_block, int offsets[4], int *boundary)
182 {
183 int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
184 int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
185 const long direct_blocks = EXT2_NDIR_BLOCKS,
186 indirect_blocks = ptrs,
187 double_blocks = (1 << (ptrs_bits * 2));
188 int n = 0;
189 int final = 0;
190
191 if (i_block < 0) {
192 ext2_warning (inode->i_sb, "ext2_block_to_path", "block < 0");
193 } else if (i_block < direct_blocks) {
194 offsets[n++] = i_block;
195 final = direct_blocks;
196 } else if ( (i_block -= direct_blocks) < indirect_blocks) {
197 offsets[n++] = EXT2_IND_BLOCK;
198 offsets[n++] = i_block;
199 final = ptrs;
200 } else if ((i_block -= indirect_blocks) < double_blocks) {
201 offsets[n++] = EXT2_DIND_BLOCK;
202 offsets[n++] = i_block >> ptrs_bits;
203 offsets[n++] = i_block & (ptrs - 1);
204 final = ptrs;
205 } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
206 offsets[n++] = EXT2_TIND_BLOCK;
207 offsets[n++] = i_block >> (ptrs_bits * 2);
208 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
209 offsets[n++] = i_block & (ptrs - 1);
210 final = ptrs;
211 } else {
212 ext2_warning (inode->i_sb, "ext2_block_to_path", "block > big");
213 }
214 if (boundary)
215 *boundary = (i_block & (ptrs - 1)) == (final - 1);
216 return n;
217 }
218
219 /**
220 * ext2_get_branch - read the chain of indirect blocks leading to data
221 * @inode: inode in question
222 * @depth: depth of the chain (1 - direct pointer, etc.)
223 * @offsets: offsets of pointers in inode/indirect blocks
224 * @chain: place to store the result
225 * @err: here we store the error value
226 *
227 * Function fills the array of triples <key, p, bh> and returns %NULL
228 * if everything went OK or the pointer to the last filled triple
229 * (incomplete one) otherwise. Upon the return chain[i].key contains
230 * the number of (i+1)-th block in the chain (as it is stored in memory,
231 * i.e. little-endian 32-bit), chain[i].p contains the address of that
232 * number (it points into struct inode for i==0 and into the bh->b_data
233 * for i>0) and chain[i].bh points to the buffer_head of i-th indirect
234 * block for i>0 and NULL for i==0. In other words, it holds the block
235 * numbers of the chain, addresses they were taken from (and where we can
236 * verify that chain did not change) and buffer_heads hosting these
237 * numbers.
238 *
239 * Function stops when it stumbles upon zero pointer (absent block)
240 * (pointer to last triple returned, *@err == 0)
241 * or when it gets an IO error reading an indirect block
242 * (ditto, *@err == -EIO)
243 * or when it notices that chain had been changed while it was reading
244 * (ditto, *@err == -EAGAIN)
245 * or when it reads all @depth-1 indirect blocks successfully and finds
246 * the whole chain, all way to the data (returns %NULL, *err == 0).
247 */
248 static Indirect *ext2_get_branch(struct inode *inode,
249 int depth,
250 int *offsets,
251 Indirect chain[4],
252 int *err)
253 {
254 struct super_block *sb = inode->i_sb;
255 Indirect *p = chain;
256 struct buffer_head *bh;
257
258 *err = 0;
259 /* i_data is not going away, no lock needed */
260 add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
261 if (!p->key)
262 goto no_block;
263 while (--depth) {
264 bh = sb_bread(sb, le32_to_cpu(p->key));
265 if (!bh)
266 goto failure;
267 read_lock(&EXT2_I(inode)->i_meta_lock);
268 if (!verify_chain(chain, p))
269 goto changed;
270 add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
271 read_unlock(&EXT2_I(inode)->i_meta_lock);
272 if (!p->key)
273 goto no_block;
274 }
275 return NULL;
276
277 changed:
278 read_unlock(&EXT2_I(inode)->i_meta_lock);
279 brelse(bh);
280 *err = -EAGAIN;
281 goto no_block;
282 failure:
283 *err = -EIO;
284 no_block:
285 return p;
286 }
287
288 /**
289 * ext2_find_near - find a place for allocation with sufficient locality
290 * @inode: owner
291 * @ind: descriptor of indirect block.
292 *
293 * This function returns the prefered place for block allocation.
294 * It is used when heuristic for sequential allocation fails.
295 * Rules are:
296 * + if there is a block to the left of our position - allocate near it.
297 * + if pointer will live in indirect block - allocate near that block.
298 * + if pointer will live in inode - allocate in the same cylinder group.
299 *
300 * In the latter case we colour the starting block by the callers PID to
301 * prevent it from clashing with concurrent allocations for a different inode
302 * in the same block group. The PID is used here so that functionally related
303 * files will be close-by on-disk.
304 *
305 * Caller must make sure that @ind is valid and will stay that way.
306 */
307
308 static unsigned long ext2_find_near(struct inode *inode, Indirect *ind)
309 {
310 struct ext2_inode_info *ei = EXT2_I(inode);
311 __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
312 __le32 *p;
313 unsigned long bg_start;
314 unsigned long colour;
315
316 /* Try to find previous block */
317 for (p = ind->p - 1; p >= start; p--)
318 if (*p)
319 return le32_to_cpu(*p);
320
321 /* No such thing, so let's try location of indirect block */
322 if (ind->bh)
323 return ind->bh->b_blocknr;
324
325 /*
326 * It is going to be refered from inode itself? OK, just put it into
327 * the same cylinder group then.
328 */
329 bg_start = (ei->i_block_group * EXT2_BLOCKS_PER_GROUP(inode->i_sb)) +
330 le32_to_cpu(EXT2_SB(inode->i_sb)->s_es->s_first_data_block);
331 colour = (current->pid % 16) *
332 (EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
333 return bg_start + colour;
334 }
335
336 /**
337 * ext2_find_goal - find a prefered place for allocation.
338 * @inode: owner
339 * @block: block we want
340 * @chain: chain of indirect blocks
341 * @partial: pointer to the last triple within a chain
342 * @goal: place to store the result.
343 *
344 * Normally this function find the prefered place for block allocation,
345 * stores it in *@goal and returns zero. If the branch had been changed
346 * under us we return -EAGAIN.
347 */
348
349 static inline int ext2_find_goal(struct inode *inode,
350 long block,
351 Indirect chain[4],
352 Indirect *partial,
353 unsigned long *goal)
354 {
355 struct ext2_inode_info *ei = EXT2_I(inode);
356 write_lock(&ei->i_meta_lock);
357 if ((block == ei->i_next_alloc_block + 1) && ei->i_next_alloc_goal) {
358 ei->i_next_alloc_block++;
359 ei->i_next_alloc_goal++;
360 }
361 if (verify_chain(chain, partial)) {
362 /*
363 * try the heuristic for sequential allocation,
364 * failing that at least try to get decent locality.
365 */
366 if (block == ei->i_next_alloc_block)
367 *goal = ei->i_next_alloc_goal;
368 if (!*goal)
369 *goal = ext2_find_near(inode, partial);
370 write_unlock(&ei->i_meta_lock);
371 return 0;
372 }
373 write_unlock(&ei->i_meta_lock);
374 return -EAGAIN;
375 }
376
377 /**
378 * ext2_alloc_branch - allocate and set up a chain of blocks.
379 * @inode: owner
380 * @num: depth of the chain (number of blocks to allocate)
381 * @offsets: offsets (in the blocks) to store the pointers to next.
382 * @branch: place to store the chain in.
383 *
384 * This function allocates @num blocks, zeroes out all but the last one,
385 * links them into chain and (if we are synchronous) writes them to disk.
386 * In other words, it prepares a branch that can be spliced onto the
387 * inode. It stores the information about that chain in the branch[], in
388 * the same format as ext2_get_branch() would do. We are calling it after
389 * we had read the existing part of chain and partial points to the last
390 * triple of that (one with zero ->key). Upon the exit we have the same
391 * picture as after the successful ext2_get_block(), excpet that in one
392 * place chain is disconnected - *branch->p is still zero (we did not
393 * set the last link), but branch->key contains the number that should
394 * be placed into *branch->p to fill that gap.
395 *
396 * If allocation fails we free all blocks we've allocated (and forget
397 * their buffer_heads) and return the error value the from failed
398 * ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
399 * as described above and return 0.
400 */
401
402 static int ext2_alloc_branch(struct inode *inode,
403 int num,
404 unsigned long goal,
405 int *offsets,
406 Indirect *branch)
407 {
408 int blocksize = inode->i_sb->s_blocksize;
409 int n = 0;
410 int err;
411 int i;
412 int parent = ext2_alloc_block(inode, goal, &err);
413
414 branch[0].key = cpu_to_le32(parent);
415 if (parent) for (n = 1; n < num; n++) {
416 struct buffer_head *bh;
417 /* Allocate the next block */
418 int nr = ext2_alloc_block(inode, parent, &err);
419 if (!nr)
420 break;
421 branch[n].key = cpu_to_le32(nr);
422 /*
423 * Get buffer_head for parent block, zero it out and set
424 * the pointer to new one, then send parent to disk.
425 */
426 bh = sb_getblk(inode->i_sb, parent);
427 lock_buffer(bh);
428 memset(bh->b_data, 0, blocksize);
429 branch[n].bh = bh;
430 branch[n].p = (__le32 *) bh->b_data + offsets[n];
431 *branch[n].p = branch[n].key;
432 set_buffer_uptodate(bh);
433 unlock_buffer(bh);
434 mark_buffer_dirty_inode(bh, inode);
435 /* We used to sync bh here if IS_SYNC(inode).
436 * But we now rely upon generic_osync_inode()
437 * and b_inode_buffers. But not for directories.
438 */
439 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
440 sync_dirty_buffer(bh);
441 parent = nr;
442 }
443 if (n == num)
444 return 0;
445
446 /* Allocation failed, free what we already allocated */
447 for (i = 1; i < n; i++)
448 bforget(branch[i].bh);
449 for (i = 0; i < n; i++)
450 ext2_free_blocks(inode, le32_to_cpu(branch[i].key), 1);
451 return err;
452 }
453
454 /**
455 * ext2_splice_branch - splice the allocated branch onto inode.
456 * @inode: owner
457 * @block: (logical) number of block we are adding
458 * @chain: chain of indirect blocks (with a missing link - see
459 * ext2_alloc_branch)
460 * @where: location of missing link
461 * @num: number of blocks we are adding
462 *
463 * This function verifies that chain (up to the missing link) had not
464 * changed, fills the missing link and does all housekeeping needed in
465 * inode (->i_blocks, etc.). In case of success we end up with the full
466 * chain to new block and return 0. Otherwise (== chain had been changed)
467 * we free the new blocks (forgetting their buffer_heads, indeed) and
468 * return -EAGAIN.
469 */
470
471 static inline int ext2_splice_branch(struct inode *inode,
472 long block,
473 Indirect chain[4],
474 Indirect *where,
475 int num)
476 {
477 struct ext2_inode_info *ei = EXT2_I(inode);
478 int i;
479
480 /* Verify that place we are splicing to is still there and vacant */
481
482 write_lock(&ei->i_meta_lock);
483 if (!verify_chain(chain, where-1) || *where->p)
484 goto changed;
485
486 /* That's it */
487
488 *where->p = where->key;
489 ei->i_next_alloc_block = block;
490 ei->i_next_alloc_goal = le32_to_cpu(where[num-1].key);
491
492 write_unlock(&ei->i_meta_lock);
493
494 /* We are done with atomic stuff, now do the rest of housekeeping */
495
496 inode->i_ctime = CURRENT_TIME_SEC;
497
498 /* had we spliced it onto indirect block? */
499 if (where->bh)
500 mark_buffer_dirty_inode(where->bh, inode);
501
502 mark_inode_dirty(inode);
503 return 0;
504
505 changed:
506 write_unlock(&ei->i_meta_lock);
507 for (i = 1; i < num; i++)
508 bforget(where[i].bh);
509 for (i = 0; i < num; i++)
510 ext2_free_blocks(inode, le32_to_cpu(where[i].key), 1);
511 return -EAGAIN;
512 }
513
514 /*
515 * Allocation strategy is simple: if we have to allocate something, we will
516 * have to go the whole way to leaf. So let's do it before attaching anything
517 * to tree, set linkage between the newborn blocks, write them if sync is
518 * required, recheck the path, free and repeat if check fails, otherwise
519 * set the last missing link (that will protect us from any truncate-generated
520 * removals - all blocks on the path are immune now) and possibly force the
521 * write on the parent block.
522 * That has a nice additional property: no special recovery from the failed
523 * allocations is needed - we simply release blocks and do not touch anything
524 * reachable from inode.
525 */
526
527 int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
528 {
529 int err = -EIO;
530 int offsets[4];
531 Indirect chain[4];
532 Indirect *partial;
533 unsigned long goal;
534 int left;
535 int boundary = 0;
536 int depth = ext2_block_to_path(inode, iblock, offsets, &boundary);
537
538 if (depth == 0)
539 goto out;
540
541 reread:
542 partial = ext2_get_branch(inode, depth, offsets, chain, &err);
543
544 /* Simplest case - block found, no allocation needed */
545 if (!partial) {
546 got_it:
547 map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
548 if (boundary)
549 set_buffer_boundary(bh_result);
550 /* Clean up and exit */
551 partial = chain+depth-1; /* the whole chain */
552 goto cleanup;
553 }
554
555 /* Next simple case - plain lookup or failed read of indirect block */
556 if (!create || err == -EIO) {
557 cleanup:
558 while (partial > chain) {
559 brelse(partial->bh);
560 partial--;
561 }
562 out:
563 return err;
564 }
565
566 /*
567 * Indirect block might be removed by truncate while we were
568 * reading it. Handling of that case (forget what we've got and
569 * reread) is taken out of the main path.
570 */
571 if (err == -EAGAIN)
572 goto changed;
573
574 goal = 0;
575 if (ext2_find_goal(inode, iblock, chain, partial, &goal) < 0)
576 goto changed;
577
578 left = (chain + depth) - partial;
579 err = ext2_alloc_branch(inode, left, goal,
580 offsets+(partial-chain), partial);
581 if (err)
582 goto cleanup;
583
584 if (ext2_splice_branch(inode, iblock, chain, partial, left) < 0)
585 goto changed;
586
587 set_buffer_new(bh_result);
588 goto got_it;
589
590 changed:
591 while (partial > chain) {
592 brelse(partial->bh);
593 partial--;
594 }
595 goto reread;
596 }
597
598 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
599 {
600 return block_write_full_page(page, ext2_get_block, wbc);
601 }
602
603 static int ext2_readpage(struct file *file, struct page *page)
604 {
605 return mpage_readpage(page, ext2_get_block);
606 }
607
608 static int
609 ext2_readpages(struct file *file, struct address_space *mapping,
610 struct list_head *pages, unsigned nr_pages)
611 {
612 return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
613 }
614
615 static int
616 ext2_prepare_write(struct file *file, struct page *page,
617 unsigned from, unsigned to)
618 {
619 return block_prepare_write(page,from,to,ext2_get_block);
620 }
621
622 static int
623 ext2_nobh_prepare_write(struct file *file, struct page *page,
624 unsigned from, unsigned to)
625 {
626 return nobh_prepare_write(page,from,to,ext2_get_block);
627 }
628
629 static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
630 {
631 return generic_block_bmap(mapping,block,ext2_get_block);
632 }
633
634 static int
635 ext2_get_blocks(struct inode *inode, sector_t iblock, unsigned long max_blocks,
636 struct buffer_head *bh_result, int create)
637 {
638 int ret;
639
640 ret = ext2_get_block(inode, iblock, bh_result, create);
641 if (ret == 0)
642 bh_result->b_size = (1 << inode->i_blkbits);
643 return ret;
644 }
645
646 static ssize_t
647 ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
648 loff_t offset, unsigned long nr_segs)
649 {
650 struct file *file = iocb->ki_filp;
651 struct inode *inode = file->f_mapping->host;
652
653 return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
654 offset, nr_segs, ext2_get_blocks, NULL);
655 }
656
657 static int
658 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
659 {
660 return mpage_writepages(mapping, wbc, ext2_get_block);
661 }
662
663 struct address_space_operations ext2_aops = {
664 .readpage = ext2_readpage,
665 .readpages = ext2_readpages,
666 .writepage = ext2_writepage,
667 .sync_page = block_sync_page,
668 .prepare_write = ext2_prepare_write,
669 .commit_write = generic_commit_write,
670 .bmap = ext2_bmap,
671 .direct_IO = ext2_direct_IO,
672 .writepages = ext2_writepages,
673 };
674
675 struct address_space_operations ext2_nobh_aops = {
676 .readpage = ext2_readpage,
677 .readpages = ext2_readpages,
678 .writepage = ext2_writepage,
679 .sync_page = block_sync_page,
680 .prepare_write = ext2_nobh_prepare_write,
681 .commit_write = nobh_commit_write,
682 .bmap = ext2_bmap,
683 .direct_IO = ext2_direct_IO,
684 .writepages = ext2_writepages,
685 };
686
687 /*
688 * Probably it should be a library function... search for first non-zero word
689 * or memcmp with zero_page, whatever is better for particular architecture.
690 * Linus?
691 */
692 static inline int all_zeroes(__le32 *p, __le32 *q)
693 {
694 while (p < q)
695 if (*p++)
696 return 0;
697 return 1;
698 }
699
700 /**
701 * ext2_find_shared - find the indirect blocks for partial truncation.
702 * @inode: inode in question
703 * @depth: depth of the affected branch
704 * @offsets: offsets of pointers in that branch (see ext2_block_to_path)
705 * @chain: place to store the pointers to partial indirect blocks
706 * @top: place to the (detached) top of branch
707 *
708 * This is a helper function used by ext2_truncate().
709 *
710 * When we do truncate() we may have to clean the ends of several indirect
711 * blocks but leave the blocks themselves alive. Block is partially
712 * truncated if some data below the new i_size is refered from it (and
713 * it is on the path to the first completely truncated data block, indeed).
714 * We have to free the top of that path along with everything to the right
715 * of the path. Since no allocation past the truncation point is possible
716 * until ext2_truncate() finishes, we may safely do the latter, but top
717 * of branch may require special attention - pageout below the truncation
718 * point might try to populate it.
719 *
720 * We atomically detach the top of branch from the tree, store the block
721 * number of its root in *@top, pointers to buffer_heads of partially
722 * truncated blocks - in @chain[].bh and pointers to their last elements
723 * that should not be removed - in @chain[].p. Return value is the pointer
724 * to last filled element of @chain.
725 *
726 * The work left to caller to do the actual freeing of subtrees:
727 * a) free the subtree starting from *@top
728 * b) free the subtrees whose roots are stored in
729 * (@chain[i].p+1 .. end of @chain[i].bh->b_data)
730 * c) free the subtrees growing from the inode past the @chain[0].p
731 * (no partially truncated stuff there).
732 */
733
734 static Indirect *ext2_find_shared(struct inode *inode,
735 int depth,
736 int offsets[4],
737 Indirect chain[4],
738 __le32 *top)
739 {
740 Indirect *partial, *p;
741 int k, err;
742
743 *top = 0;
744 for (k = depth; k > 1 && !offsets[k-1]; k--)
745 ;
746 partial = ext2_get_branch(inode, k, offsets, chain, &err);
747 if (!partial)
748 partial = chain + k-1;
749 /*
750 * If the branch acquired continuation since we've looked at it -
751 * fine, it should all survive and (new) top doesn't belong to us.
752 */
753 write_lock(&EXT2_I(inode)->i_meta_lock);
754 if (!partial->key && *partial->p) {
755 write_unlock(&EXT2_I(inode)->i_meta_lock);
756 goto no_top;
757 }
758 for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
759 ;
760 /*
761 * OK, we've found the last block that must survive. The rest of our
762 * branch should be detached before unlocking. However, if that rest
763 * of branch is all ours and does not grow immediately from the inode
764 * it's easier to cheat and just decrement partial->p.
765 */
766 if (p == chain + k - 1 && p > chain) {
767 p->p--;
768 } else {
769 *top = *p->p;
770 *p->p = 0;
771 }
772 write_unlock(&EXT2_I(inode)->i_meta_lock);
773
774 while(partial > p)
775 {
776 brelse(partial->bh);
777 partial--;
778 }
779 no_top:
780 return partial;
781 }
782
783 /**
784 * ext2_free_data - free a list of data blocks
785 * @inode: inode we are dealing with
786 * @p: array of block numbers
787 * @q: points immediately past the end of array
788 *
789 * We are freeing all blocks refered from that array (numbers are
790 * stored as little-endian 32-bit) and updating @inode->i_blocks
791 * appropriately.
792 */
793 static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
794 {
795 unsigned long block_to_free = 0, count = 0;
796 unsigned long nr;
797
798 for ( ; p < q ; p++) {
799 nr = le32_to_cpu(*p);
800 if (nr) {
801 *p = 0;
802 /* accumulate blocks to free if they're contiguous */
803 if (count == 0)
804 goto free_this;
805 else if (block_to_free == nr - count)
806 count++;
807 else {
808 mark_inode_dirty(inode);
809 ext2_free_blocks (inode, block_to_free, count);
810 free_this:
811 block_to_free = nr;
812 count = 1;
813 }
814 }
815 }
816 if (count > 0) {
817 mark_inode_dirty(inode);
818 ext2_free_blocks (inode, block_to_free, count);
819 }
820 }
821
822 /**
823 * ext2_free_branches - free an array of branches
824 * @inode: inode we are dealing with
825 * @p: array of block numbers
826 * @q: pointer immediately past the end of array
827 * @depth: depth of the branches to free
828 *
829 * We are freeing all blocks refered from these branches (numbers are
830 * stored as little-endian 32-bit) and updating @inode->i_blocks
831 * appropriately.
832 */
833 static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
834 {
835 struct buffer_head * bh;
836 unsigned long nr;
837
838 if (depth--) {
839 int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
840 for ( ; p < q ; p++) {
841 nr = le32_to_cpu(*p);
842 if (!nr)
843 continue;
844 *p = 0;
845 bh = sb_bread(inode->i_sb, nr);
846 /*
847 * A read failure? Report error and clear slot
848 * (should be rare).
849 */
850 if (!bh) {
851 ext2_error(inode->i_sb, "ext2_free_branches",
852 "Read failure, inode=%ld, block=%ld",
853 inode->i_ino, nr);
854 continue;
855 }
856 ext2_free_branches(inode,
857 (__le32*)bh->b_data,
858 (__le32*)bh->b_data + addr_per_block,
859 depth);
860 bforget(bh);
861 ext2_free_blocks(inode, nr, 1);
862 mark_inode_dirty(inode);
863 }
864 } else
865 ext2_free_data(inode, p, q);
866 }
867
868 void ext2_truncate (struct inode * inode)
869 {
870 __le32 *i_data = EXT2_I(inode)->i_data;
871 int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
872 int offsets[4];
873 Indirect chain[4];
874 Indirect *partial;
875 __le32 nr = 0;
876 int n;
877 long iblock;
878 unsigned blocksize;
879
880 if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
881 S_ISLNK(inode->i_mode)))
882 return;
883 if (ext2_inode_is_fast_symlink(inode))
884 return;
885 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
886 return;
887
888 ext2_discard_prealloc(inode);
889
890 blocksize = inode->i_sb->s_blocksize;
891 iblock = (inode->i_size + blocksize-1)
892 >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
893
894 if (test_opt(inode->i_sb, NOBH))
895 nobh_truncate_page(inode->i_mapping, inode->i_size);
896 else
897 block_truncate_page(inode->i_mapping,
898 inode->i_size, ext2_get_block);
899
900 n = ext2_block_to_path(inode, iblock, offsets, NULL);
901 if (n == 0)
902 return;
903
904 if (n == 1) {
905 ext2_free_data(inode, i_data+offsets[0],
906 i_data + EXT2_NDIR_BLOCKS);
907 goto do_indirects;
908 }
909
910 partial = ext2_find_shared(inode, n, offsets, chain, &nr);
911 /* Kill the top of shared branch (already detached) */
912 if (nr) {
913 if (partial == chain)
914 mark_inode_dirty(inode);
915 else
916 mark_buffer_dirty_inode(partial->bh, inode);
917 ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
918 }
919 /* Clear the ends of indirect blocks on the shared branch */
920 while (partial > chain) {
921 ext2_free_branches(inode,
922 partial->p + 1,
923 (__le32*)partial->bh->b_data+addr_per_block,
924 (chain+n-1) - partial);
925 mark_buffer_dirty_inode(partial->bh, inode);
926 brelse (partial->bh);
927 partial--;
928 }
929 do_indirects:
930 /* Kill the remaining (whole) subtrees */
931 switch (offsets[0]) {
932 default:
933 nr = i_data[EXT2_IND_BLOCK];
934 if (nr) {
935 i_data[EXT2_IND_BLOCK] = 0;
936 mark_inode_dirty(inode);
937 ext2_free_branches(inode, &nr, &nr+1, 1);
938 }
939 case EXT2_IND_BLOCK:
940 nr = i_data[EXT2_DIND_BLOCK];
941 if (nr) {
942 i_data[EXT2_DIND_BLOCK] = 0;
943 mark_inode_dirty(inode);
944 ext2_free_branches(inode, &nr, &nr+1, 2);
945 }
946 case EXT2_DIND_BLOCK:
947 nr = i_data[EXT2_TIND_BLOCK];
948 if (nr) {
949 i_data[EXT2_TIND_BLOCK] = 0;
950 mark_inode_dirty(inode);
951 ext2_free_branches(inode, &nr, &nr+1, 3);
952 }
953 case EXT2_TIND_BLOCK:
954 ;
955 }
956 inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
957 if (inode_needs_sync(inode)) {
958 sync_mapping_buffers(inode->i_mapping);
959 ext2_sync_inode (inode);
960 } else {
961 mark_inode_dirty(inode);
962 }
963 }
964
965 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
966 struct buffer_head **p)
967 {
968 struct buffer_head * bh;
969 unsigned long block_group;
970 unsigned long block;
971 unsigned long offset;
972 struct ext2_group_desc * gdp;
973
974 *p = NULL;
975 if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
976 ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
977 goto Einval;
978
979 block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
980 gdp = ext2_get_group_desc(sb, block_group, &bh);
981 if (!gdp)
982 goto Egdp;
983 /*
984 * Figure out the offset within the block group inode table
985 */
986 offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
987 block = le32_to_cpu(gdp->bg_inode_table) +
988 (offset >> EXT2_BLOCK_SIZE_BITS(sb));
989 if (!(bh = sb_bread(sb, block)))
990 goto Eio;
991
992 *p = bh;
993 offset &= (EXT2_BLOCK_SIZE(sb) - 1);
994 return (struct ext2_inode *) (bh->b_data + offset);
995
996 Einval:
997 ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
998 (unsigned long) ino);
999 return ERR_PTR(-EINVAL);
1000 Eio:
1001 ext2_error(sb, "ext2_get_inode",
1002 "unable to read inode block - inode=%lu, block=%lu",
1003 (unsigned long) ino, block);
1004 Egdp:
1005 return ERR_PTR(-EIO);
1006 }
1007
1008 void ext2_set_inode_flags(struct inode *inode)
1009 {
1010 unsigned int flags = EXT2_I(inode)->i_flags;
1011
1012 inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
1013 if (flags & EXT2_SYNC_FL)
1014 inode->i_flags |= S_SYNC;
1015 if (flags & EXT2_APPEND_FL)
1016 inode->i_flags |= S_APPEND;
1017 if (flags & EXT2_IMMUTABLE_FL)
1018 inode->i_flags |= S_IMMUTABLE;
1019 if (flags & EXT2_NOATIME_FL)
1020 inode->i_flags |= S_NOATIME;
1021 if (flags & EXT2_DIRSYNC_FL)
1022 inode->i_flags |= S_DIRSYNC;
1023 }
1024
1025 void ext2_read_inode (struct inode * inode)
1026 {
1027 struct ext2_inode_info *ei = EXT2_I(inode);
1028 ino_t ino = inode->i_ino;
1029 struct buffer_head * bh;
1030 struct ext2_inode * raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1031 int n;
1032
1033 #ifdef CONFIG_EXT2_FS_POSIX_ACL
1034 ei->i_acl = EXT2_ACL_NOT_CACHED;
1035 ei->i_default_acl = EXT2_ACL_NOT_CACHED;
1036 #endif
1037 if (IS_ERR(raw_inode))
1038 goto bad_inode;
1039
1040 inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1041 inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1042 inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1043 if (!(test_opt (inode->i_sb, NO_UID32))) {
1044 inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1045 inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1046 }
1047 inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
1048 inode->i_size = le32_to_cpu(raw_inode->i_size);
1049 inode->i_atime.tv_sec = le32_to_cpu(raw_inode->i_atime);
1050 inode->i_ctime.tv_sec = le32_to_cpu(raw_inode->i_ctime);
1051 inode->i_mtime.tv_sec = le32_to_cpu(raw_inode->i_mtime);
1052 inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1053 ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1054 /* We now have enough fields to check if the inode was active or not.
1055 * This is needed because nfsd might try to access dead inodes
1056 * the test is that same one that e2fsck uses
1057 * NeilBrown 1999oct15
1058 */
1059 if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1060 /* this inode is deleted */
1061 brelse (bh);
1062 goto bad_inode;
1063 }
1064 inode->i_blksize = PAGE_SIZE; /* This is the optimal IO size (for stat), not the fs block size */
1065 inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1066 ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1067 ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1068 ei->i_frag_no = raw_inode->i_frag;
1069 ei->i_frag_size = raw_inode->i_fsize;
1070 ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1071 ei->i_dir_acl = 0;
1072 if (S_ISREG(inode->i_mode))
1073 inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1074 else
1075 ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1076 ei->i_dtime = 0;
1077 inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1078 ei->i_state = 0;
1079 ei->i_next_alloc_block = 0;
1080 ei->i_next_alloc_goal = 0;
1081 ei->i_prealloc_count = 0;
1082 ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1083 ei->i_dir_start_lookup = 0;
1084
1085 /*
1086 * NOTE! The in-memory inode i_data array is in little-endian order
1087 * even on big-endian machines: we do NOT byteswap the block numbers!
1088 */
1089 for (n = 0; n < EXT2_N_BLOCKS; n++)
1090 ei->i_data[n] = raw_inode->i_block[n];
1091
1092 if (S_ISREG(inode->i_mode)) {
1093 inode->i_op = &ext2_file_inode_operations;
1094 inode->i_fop = &ext2_file_operations;
1095 if (test_opt(inode->i_sb, NOBH))
1096 inode->i_mapping->a_ops = &ext2_nobh_aops;
1097 else
1098 inode->i_mapping->a_ops = &ext2_aops;
1099 } else if (S_ISDIR(inode->i_mode)) {
1100 inode->i_op = &ext2_dir_inode_operations;
1101 inode->i_fop = &ext2_dir_operations;
1102 if (test_opt(inode->i_sb, NOBH))
1103 inode->i_mapping->a_ops = &ext2_nobh_aops;
1104 else
1105 inode->i_mapping->a_ops = &ext2_aops;
1106 } else if (S_ISLNK(inode->i_mode)) {
1107 if (ext2_inode_is_fast_symlink(inode))
1108 inode->i_op = &ext2_fast_symlink_inode_operations;
1109 else {
1110 inode->i_op = &ext2_symlink_inode_operations;
1111 if (test_opt(inode->i_sb, NOBH))
1112 inode->i_mapping->a_ops = &ext2_nobh_aops;
1113 else
1114 inode->i_mapping->a_ops = &ext2_aops;
1115 }
1116 } else {
1117 inode->i_op = &ext2_special_inode_operations;
1118 if (raw_inode->i_block[0])
1119 init_special_inode(inode, inode->i_mode,
1120 old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1121 else
1122 init_special_inode(inode, inode->i_mode,
1123 new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1124 }
1125 brelse (bh);
1126 ext2_set_inode_flags(inode);
1127 return;
1128
1129 bad_inode:
1130 make_bad_inode(inode);
1131 return;
1132 }
1133
1134 static int ext2_update_inode(struct inode * inode, int do_sync)
1135 {
1136 struct ext2_inode_info *ei = EXT2_I(inode);
1137 struct super_block *sb = inode->i_sb;
1138 ino_t ino = inode->i_ino;
1139 uid_t uid = inode->i_uid;
1140 gid_t gid = inode->i_gid;
1141 struct buffer_head * bh;
1142 struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1143 int n;
1144 int err = 0;
1145
1146 if (IS_ERR(raw_inode))
1147 return -EIO;
1148
1149 /* For fields not not tracking in the in-memory inode,
1150 * initialise them to zero for new inodes. */
1151 if (ei->i_state & EXT2_STATE_NEW)
1152 memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1153
1154 raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1155 if (!(test_opt(sb, NO_UID32))) {
1156 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1157 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1158 /*
1159 * Fix up interoperability with old kernels. Otherwise, old inodes get
1160 * re-used with the upper 16 bits of the uid/gid intact
1161 */
1162 if (!ei->i_dtime) {
1163 raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1164 raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1165 } else {
1166 raw_inode->i_uid_high = 0;
1167 raw_inode->i_gid_high = 0;
1168 }
1169 } else {
1170 raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1171 raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1172 raw_inode->i_uid_high = 0;
1173 raw_inode->i_gid_high = 0;
1174 }
1175 raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1176 raw_inode->i_size = cpu_to_le32(inode->i_size);
1177 raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1178 raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1179 raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1180
1181 raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1182 raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1183 raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1184 raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1185 raw_inode->i_frag = ei->i_frag_no;
1186 raw_inode->i_fsize = ei->i_frag_size;
1187 raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1188 if (!S_ISREG(inode->i_mode))
1189 raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1190 else {
1191 raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1192 if (inode->i_size > 0x7fffffffULL) {
1193 if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1194 EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1195 EXT2_SB(sb)->s_es->s_rev_level ==
1196 cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1197 /* If this is the first large file
1198 * created, add a flag to the superblock.
1199 */
1200 lock_kernel();
1201 ext2_update_dynamic_rev(sb);
1202 EXT2_SET_RO_COMPAT_FEATURE(sb,
1203 EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1204 unlock_kernel();
1205 ext2_write_super(sb);
1206 }
1207 }
1208 }
1209
1210 raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1211 if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1212 if (old_valid_dev(inode->i_rdev)) {
1213 raw_inode->i_block[0] =
1214 cpu_to_le32(old_encode_dev(inode->i_rdev));
1215 raw_inode->i_block[1] = 0;
1216 } else {
1217 raw_inode->i_block[0] = 0;
1218 raw_inode->i_block[1] =
1219 cpu_to_le32(new_encode_dev(inode->i_rdev));
1220 raw_inode->i_block[2] = 0;
1221 }
1222 } else for (n = 0; n < EXT2_N_BLOCKS; n++)
1223 raw_inode->i_block[n] = ei->i_data[n];
1224 mark_buffer_dirty(bh);
1225 if (do_sync) {
1226 sync_dirty_buffer(bh);
1227 if (buffer_req(bh) && !buffer_uptodate(bh)) {
1228 printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1229 sb->s_id, (unsigned long) ino);
1230 err = -EIO;
1231 }
1232 }
1233 ei->i_state &= ~EXT2_STATE_NEW;
1234 brelse (bh);
1235 return err;
1236 }
1237
1238 int ext2_write_inode(struct inode *inode, int wait)
1239 {
1240 return ext2_update_inode(inode, wait);
1241 }
1242
1243 int ext2_sync_inode(struct inode *inode)
1244 {
1245 struct writeback_control wbc = {
1246 .sync_mode = WB_SYNC_ALL,
1247 .nr_to_write = 0, /* sys_fsync did this */
1248 };
1249 return sync_inode(inode, &wbc);
1250 }
1251
1252 int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1253 {
1254 struct inode *inode = dentry->d_inode;
1255 int error;
1256
1257 error = inode_change_ok(inode, iattr);
1258 if (error)
1259 return error;
1260 if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||
1261 (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {
1262 error = DQUOT_TRANSFER(inode, iattr) ? -EDQUOT : 0;
1263 if (error)
1264 return error;
1265 }
1266 error = inode_setattr(inode, iattr);
1267 if (!error && (iattr->ia_valid & ATTR_MODE))
1268 error = ext2_acl_chmod(inode);
1269 return error;
1270 }
1271
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