xref: /openbmc/linux/fs/ext2/inode.c (revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2)
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 int ext2_nobh_writepage(struct page *page,
630 			struct writeback_control *wbc)
631 {
632 	return nobh_writepage(page, ext2_get_block, wbc);
633 }
634 
635 static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
636 {
637 	return generic_block_bmap(mapping,block,ext2_get_block);
638 }
639 
640 static int
641 ext2_get_blocks(struct inode *inode, sector_t iblock, unsigned long max_blocks,
642 			struct buffer_head *bh_result, int create)
643 {
644 	int ret;
645 
646 	ret = ext2_get_block(inode, iblock, bh_result, create);
647 	if (ret == 0)
648 		bh_result->b_size = (1 << inode->i_blkbits);
649 	return ret;
650 }
651 
652 static ssize_t
653 ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
654 			loff_t offset, unsigned long nr_segs)
655 {
656 	struct file *file = iocb->ki_filp;
657 	struct inode *inode = file->f_mapping->host;
658 
659 	return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
660 				offset, nr_segs, ext2_get_blocks, NULL);
661 }
662 
663 static int
664 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
665 {
666 	return mpage_writepages(mapping, wbc, ext2_get_block);
667 }
668 
669 struct address_space_operations ext2_aops = {
670 	.readpage		= ext2_readpage,
671 	.readpages		= ext2_readpages,
672 	.writepage		= ext2_writepage,
673 	.sync_page		= block_sync_page,
674 	.prepare_write		= ext2_prepare_write,
675 	.commit_write		= generic_commit_write,
676 	.bmap			= ext2_bmap,
677 	.direct_IO		= ext2_direct_IO,
678 	.writepages		= ext2_writepages,
679 };
680 
681 struct address_space_operations ext2_nobh_aops = {
682 	.readpage		= ext2_readpage,
683 	.readpages		= ext2_readpages,
684 	.writepage		= ext2_nobh_writepage,
685 	.sync_page		= block_sync_page,
686 	.prepare_write		= ext2_nobh_prepare_write,
687 	.commit_write		= nobh_commit_write,
688 	.bmap			= ext2_bmap,
689 	.direct_IO		= ext2_direct_IO,
690 	.writepages		= ext2_writepages,
691 };
692 
693 /*
694  * Probably it should be a library function... search for first non-zero word
695  * or memcmp with zero_page, whatever is better for particular architecture.
696  * Linus?
697  */
698 static inline int all_zeroes(__le32 *p, __le32 *q)
699 {
700 	while (p < q)
701 		if (*p++)
702 			return 0;
703 	return 1;
704 }
705 
706 /**
707  *	ext2_find_shared - find the indirect blocks for partial truncation.
708  *	@inode:	  inode in question
709  *	@depth:	  depth of the affected branch
710  *	@offsets: offsets of pointers in that branch (see ext2_block_to_path)
711  *	@chain:	  place to store the pointers to partial indirect blocks
712  *	@top:	  place to the (detached) top of branch
713  *
714  *	This is a helper function used by ext2_truncate().
715  *
716  *	When we do truncate() we may have to clean the ends of several indirect
717  *	blocks but leave the blocks themselves alive. Block is partially
718  *	truncated if some data below the new i_size is refered from it (and
719  *	it is on the path to the first completely truncated data block, indeed).
720  *	We have to free the top of that path along with everything to the right
721  *	of the path. Since no allocation past the truncation point is possible
722  *	until ext2_truncate() finishes, we may safely do the latter, but top
723  *	of branch may require special attention - pageout below the truncation
724  *	point might try to populate it.
725  *
726  *	We atomically detach the top of branch from the tree, store the block
727  *	number of its root in *@top, pointers to buffer_heads of partially
728  *	truncated blocks - in @chain[].bh and pointers to their last elements
729  *	that should not be removed - in @chain[].p. Return value is the pointer
730  *	to last filled element of @chain.
731  *
732  *	The work left to caller to do the actual freeing of subtrees:
733  *		a) free the subtree starting from *@top
734  *		b) free the subtrees whose roots are stored in
735  *			(@chain[i].p+1 .. end of @chain[i].bh->b_data)
736  *		c) free the subtrees growing from the inode past the @chain[0].p
737  *			(no partially truncated stuff there).
738  */
739 
740 static Indirect *ext2_find_shared(struct inode *inode,
741 				int depth,
742 				int offsets[4],
743 				Indirect chain[4],
744 				__le32 *top)
745 {
746 	Indirect *partial, *p;
747 	int k, err;
748 
749 	*top = 0;
750 	for (k = depth; k > 1 && !offsets[k-1]; k--)
751 		;
752 	partial = ext2_get_branch(inode, k, offsets, chain, &err);
753 	if (!partial)
754 		partial = chain + k-1;
755 	/*
756 	 * If the branch acquired continuation since we've looked at it -
757 	 * fine, it should all survive and (new) top doesn't belong to us.
758 	 */
759 	write_lock(&EXT2_I(inode)->i_meta_lock);
760 	if (!partial->key && *partial->p) {
761 		write_unlock(&EXT2_I(inode)->i_meta_lock);
762 		goto no_top;
763 	}
764 	for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
765 		;
766 	/*
767 	 * OK, we've found the last block that must survive. The rest of our
768 	 * branch should be detached before unlocking. However, if that rest
769 	 * of branch is all ours and does not grow immediately from the inode
770 	 * it's easier to cheat and just decrement partial->p.
771 	 */
772 	if (p == chain + k - 1 && p > chain) {
773 		p->p--;
774 	} else {
775 		*top = *p->p;
776 		*p->p = 0;
777 	}
778 	write_unlock(&EXT2_I(inode)->i_meta_lock);
779 
780 	while(partial > p)
781 	{
782 		brelse(partial->bh);
783 		partial--;
784 	}
785 no_top:
786 	return partial;
787 }
788 
789 /**
790  *	ext2_free_data - free a list of data blocks
791  *	@inode:	inode we are dealing with
792  *	@p:	array of block numbers
793  *	@q:	points immediately past the end of array
794  *
795  *	We are freeing all blocks refered from that array (numbers are
796  *	stored as little-endian 32-bit) and updating @inode->i_blocks
797  *	appropriately.
798  */
799 static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
800 {
801 	unsigned long block_to_free = 0, count = 0;
802 	unsigned long nr;
803 
804 	for ( ; p < q ; p++) {
805 		nr = le32_to_cpu(*p);
806 		if (nr) {
807 			*p = 0;
808 			/* accumulate blocks to free if they're contiguous */
809 			if (count == 0)
810 				goto free_this;
811 			else if (block_to_free == nr - count)
812 				count++;
813 			else {
814 				mark_inode_dirty(inode);
815 				ext2_free_blocks (inode, block_to_free, count);
816 			free_this:
817 				block_to_free = nr;
818 				count = 1;
819 			}
820 		}
821 	}
822 	if (count > 0) {
823 		mark_inode_dirty(inode);
824 		ext2_free_blocks (inode, block_to_free, count);
825 	}
826 }
827 
828 /**
829  *	ext2_free_branches - free an array of branches
830  *	@inode:	inode we are dealing with
831  *	@p:	array of block numbers
832  *	@q:	pointer immediately past the end of array
833  *	@depth:	depth of the branches to free
834  *
835  *	We are freeing all blocks refered from these branches (numbers are
836  *	stored as little-endian 32-bit) and updating @inode->i_blocks
837  *	appropriately.
838  */
839 static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
840 {
841 	struct buffer_head * bh;
842 	unsigned long nr;
843 
844 	if (depth--) {
845 		int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
846 		for ( ; p < q ; p++) {
847 			nr = le32_to_cpu(*p);
848 			if (!nr)
849 				continue;
850 			*p = 0;
851 			bh = sb_bread(inode->i_sb, nr);
852 			/*
853 			 * A read failure? Report error and clear slot
854 			 * (should be rare).
855 			 */
856 			if (!bh) {
857 				ext2_error(inode->i_sb, "ext2_free_branches",
858 					"Read failure, inode=%ld, block=%ld",
859 					inode->i_ino, nr);
860 				continue;
861 			}
862 			ext2_free_branches(inode,
863 					   (__le32*)bh->b_data,
864 					   (__le32*)bh->b_data + addr_per_block,
865 					   depth);
866 			bforget(bh);
867 			ext2_free_blocks(inode, nr, 1);
868 			mark_inode_dirty(inode);
869 		}
870 	} else
871 		ext2_free_data(inode, p, q);
872 }
873 
874 void ext2_truncate (struct inode * inode)
875 {
876 	__le32 *i_data = EXT2_I(inode)->i_data;
877 	int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
878 	int offsets[4];
879 	Indirect chain[4];
880 	Indirect *partial;
881 	__le32 nr = 0;
882 	int n;
883 	long iblock;
884 	unsigned blocksize;
885 
886 	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
887 	    S_ISLNK(inode->i_mode)))
888 		return;
889 	if (ext2_inode_is_fast_symlink(inode))
890 		return;
891 	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
892 		return;
893 
894 	ext2_discard_prealloc(inode);
895 
896 	blocksize = inode->i_sb->s_blocksize;
897 	iblock = (inode->i_size + blocksize-1)
898 					>> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
899 
900 	if (test_opt(inode->i_sb, NOBH))
901 		nobh_truncate_page(inode->i_mapping, inode->i_size);
902 	else
903 		block_truncate_page(inode->i_mapping,
904 				inode->i_size, ext2_get_block);
905 
906 	n = ext2_block_to_path(inode, iblock, offsets, NULL);
907 	if (n == 0)
908 		return;
909 
910 	if (n == 1) {
911 		ext2_free_data(inode, i_data+offsets[0],
912 					i_data + EXT2_NDIR_BLOCKS);
913 		goto do_indirects;
914 	}
915 
916 	partial = ext2_find_shared(inode, n, offsets, chain, &nr);
917 	/* Kill the top of shared branch (already detached) */
918 	if (nr) {
919 		if (partial == chain)
920 			mark_inode_dirty(inode);
921 		else
922 			mark_buffer_dirty_inode(partial->bh, inode);
923 		ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
924 	}
925 	/* Clear the ends of indirect blocks on the shared branch */
926 	while (partial > chain) {
927 		ext2_free_branches(inode,
928 				   partial->p + 1,
929 				   (__le32*)partial->bh->b_data+addr_per_block,
930 				   (chain+n-1) - partial);
931 		mark_buffer_dirty_inode(partial->bh, inode);
932 		brelse (partial->bh);
933 		partial--;
934 	}
935 do_indirects:
936 	/* Kill the remaining (whole) subtrees */
937 	switch (offsets[0]) {
938 		default:
939 			nr = i_data[EXT2_IND_BLOCK];
940 			if (nr) {
941 				i_data[EXT2_IND_BLOCK] = 0;
942 				mark_inode_dirty(inode);
943 				ext2_free_branches(inode, &nr, &nr+1, 1);
944 			}
945 		case EXT2_IND_BLOCK:
946 			nr = i_data[EXT2_DIND_BLOCK];
947 			if (nr) {
948 				i_data[EXT2_DIND_BLOCK] = 0;
949 				mark_inode_dirty(inode);
950 				ext2_free_branches(inode, &nr, &nr+1, 2);
951 			}
952 		case EXT2_DIND_BLOCK:
953 			nr = i_data[EXT2_TIND_BLOCK];
954 			if (nr) {
955 				i_data[EXT2_TIND_BLOCK] = 0;
956 				mark_inode_dirty(inode);
957 				ext2_free_branches(inode, &nr, &nr+1, 3);
958 			}
959 		case EXT2_TIND_BLOCK:
960 			;
961 	}
962 	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
963 	if (inode_needs_sync(inode)) {
964 		sync_mapping_buffers(inode->i_mapping);
965 		ext2_sync_inode (inode);
966 	} else {
967 		mark_inode_dirty(inode);
968 	}
969 }
970 
971 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
972 					struct buffer_head **p)
973 {
974 	struct buffer_head * bh;
975 	unsigned long block_group;
976 	unsigned long block;
977 	unsigned long offset;
978 	struct ext2_group_desc * gdp;
979 
980 	*p = NULL;
981 	if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
982 	    ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
983 		goto Einval;
984 
985 	block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
986 	gdp = ext2_get_group_desc(sb, block_group, &bh);
987 	if (!gdp)
988 		goto Egdp;
989 	/*
990 	 * Figure out the offset within the block group inode table
991 	 */
992 	offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
993 	block = le32_to_cpu(gdp->bg_inode_table) +
994 		(offset >> EXT2_BLOCK_SIZE_BITS(sb));
995 	if (!(bh = sb_bread(sb, block)))
996 		goto Eio;
997 
998 	*p = bh;
999 	offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1000 	return (struct ext2_inode *) (bh->b_data + offset);
1001 
1002 Einval:
1003 	ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1004 		   (unsigned long) ino);
1005 	return ERR_PTR(-EINVAL);
1006 Eio:
1007 	ext2_error(sb, "ext2_get_inode",
1008 		   "unable to read inode block - inode=%lu, block=%lu",
1009 		   (unsigned long) ino, block);
1010 Egdp:
1011 	return ERR_PTR(-EIO);
1012 }
1013 
1014 void ext2_set_inode_flags(struct inode *inode)
1015 {
1016 	unsigned int flags = EXT2_I(inode)->i_flags;
1017 
1018 	inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
1019 	if (flags & EXT2_SYNC_FL)
1020 		inode->i_flags |= S_SYNC;
1021 	if (flags & EXT2_APPEND_FL)
1022 		inode->i_flags |= S_APPEND;
1023 	if (flags & EXT2_IMMUTABLE_FL)
1024 		inode->i_flags |= S_IMMUTABLE;
1025 	if (flags & EXT2_NOATIME_FL)
1026 		inode->i_flags |= S_NOATIME;
1027 	if (flags & EXT2_DIRSYNC_FL)
1028 		inode->i_flags |= S_DIRSYNC;
1029 }
1030 
1031 void ext2_read_inode (struct inode * inode)
1032 {
1033 	struct ext2_inode_info *ei = EXT2_I(inode);
1034 	ino_t ino = inode->i_ino;
1035 	struct buffer_head * bh;
1036 	struct ext2_inode * raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1037 	int n;
1038 
1039 #ifdef CONFIG_EXT2_FS_POSIX_ACL
1040 	ei->i_acl = EXT2_ACL_NOT_CACHED;
1041 	ei->i_default_acl = EXT2_ACL_NOT_CACHED;
1042 #endif
1043 	if (IS_ERR(raw_inode))
1044  		goto bad_inode;
1045 
1046 	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1047 	inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1048 	inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1049 	if (!(test_opt (inode->i_sb, NO_UID32))) {
1050 		inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1051 		inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1052 	}
1053 	inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
1054 	inode->i_size = le32_to_cpu(raw_inode->i_size);
1055 	inode->i_atime.tv_sec = le32_to_cpu(raw_inode->i_atime);
1056 	inode->i_ctime.tv_sec = le32_to_cpu(raw_inode->i_ctime);
1057 	inode->i_mtime.tv_sec = le32_to_cpu(raw_inode->i_mtime);
1058 	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1059 	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1060 	/* We now have enough fields to check if the inode was active or not.
1061 	 * This is needed because nfsd might try to access dead inodes
1062 	 * the test is that same one that e2fsck uses
1063 	 * NeilBrown 1999oct15
1064 	 */
1065 	if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1066 		/* this inode is deleted */
1067 		brelse (bh);
1068 		goto bad_inode;
1069 	}
1070 	inode->i_blksize = PAGE_SIZE;	/* This is the optimal IO size (for stat), not the fs block size */
1071 	inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1072 	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1073 	ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1074 	ei->i_frag_no = raw_inode->i_frag;
1075 	ei->i_frag_size = raw_inode->i_fsize;
1076 	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1077 	ei->i_dir_acl = 0;
1078 	if (S_ISREG(inode->i_mode))
1079 		inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1080 	else
1081 		ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1082 	ei->i_dtime = 0;
1083 	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1084 	ei->i_state = 0;
1085 	ei->i_next_alloc_block = 0;
1086 	ei->i_next_alloc_goal = 0;
1087 	ei->i_prealloc_count = 0;
1088 	ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1089 	ei->i_dir_start_lookup = 0;
1090 
1091 	/*
1092 	 * NOTE! The in-memory inode i_data array is in little-endian order
1093 	 * even on big-endian machines: we do NOT byteswap the block numbers!
1094 	 */
1095 	for (n = 0; n < EXT2_N_BLOCKS; n++)
1096 		ei->i_data[n] = raw_inode->i_block[n];
1097 
1098 	if (S_ISREG(inode->i_mode)) {
1099 		inode->i_op = &ext2_file_inode_operations;
1100 		inode->i_fop = &ext2_file_operations;
1101 		if (test_opt(inode->i_sb, NOBH))
1102 			inode->i_mapping->a_ops = &ext2_nobh_aops;
1103 		else
1104 			inode->i_mapping->a_ops = &ext2_aops;
1105 	} else if (S_ISDIR(inode->i_mode)) {
1106 		inode->i_op = &ext2_dir_inode_operations;
1107 		inode->i_fop = &ext2_dir_operations;
1108 		if (test_opt(inode->i_sb, NOBH))
1109 			inode->i_mapping->a_ops = &ext2_nobh_aops;
1110 		else
1111 			inode->i_mapping->a_ops = &ext2_aops;
1112 	} else if (S_ISLNK(inode->i_mode)) {
1113 		if (ext2_inode_is_fast_symlink(inode))
1114 			inode->i_op = &ext2_fast_symlink_inode_operations;
1115 		else {
1116 			inode->i_op = &ext2_symlink_inode_operations;
1117 			if (test_opt(inode->i_sb, NOBH))
1118 				inode->i_mapping->a_ops = &ext2_nobh_aops;
1119 			else
1120 				inode->i_mapping->a_ops = &ext2_aops;
1121 		}
1122 	} else {
1123 		inode->i_op = &ext2_special_inode_operations;
1124 		if (raw_inode->i_block[0])
1125 			init_special_inode(inode, inode->i_mode,
1126 			   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1127 		else
1128 			init_special_inode(inode, inode->i_mode,
1129 			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1130 	}
1131 	brelse (bh);
1132 	ext2_set_inode_flags(inode);
1133 	return;
1134 
1135 bad_inode:
1136 	make_bad_inode(inode);
1137 	return;
1138 }
1139 
1140 static int ext2_update_inode(struct inode * inode, int do_sync)
1141 {
1142 	struct ext2_inode_info *ei = EXT2_I(inode);
1143 	struct super_block *sb = inode->i_sb;
1144 	ino_t ino = inode->i_ino;
1145 	uid_t uid = inode->i_uid;
1146 	gid_t gid = inode->i_gid;
1147 	struct buffer_head * bh;
1148 	struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1149 	int n;
1150 	int err = 0;
1151 
1152 	if (IS_ERR(raw_inode))
1153  		return -EIO;
1154 
1155 	/* For fields not not tracking in the in-memory inode,
1156 	 * initialise them to zero for new inodes. */
1157 	if (ei->i_state & EXT2_STATE_NEW)
1158 		memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1159 
1160 	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1161 	if (!(test_opt(sb, NO_UID32))) {
1162 		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1163 		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1164 /*
1165  * Fix up interoperability with old kernels. Otherwise, old inodes get
1166  * re-used with the upper 16 bits of the uid/gid intact
1167  */
1168 		if (!ei->i_dtime) {
1169 			raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1170 			raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1171 		} else {
1172 			raw_inode->i_uid_high = 0;
1173 			raw_inode->i_gid_high = 0;
1174 		}
1175 	} else {
1176 		raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1177 		raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1178 		raw_inode->i_uid_high = 0;
1179 		raw_inode->i_gid_high = 0;
1180 	}
1181 	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1182 	raw_inode->i_size = cpu_to_le32(inode->i_size);
1183 	raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1184 	raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1185 	raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1186 
1187 	raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1188 	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1189 	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1190 	raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1191 	raw_inode->i_frag = ei->i_frag_no;
1192 	raw_inode->i_fsize = ei->i_frag_size;
1193 	raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1194 	if (!S_ISREG(inode->i_mode))
1195 		raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1196 	else {
1197 		raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1198 		if (inode->i_size > 0x7fffffffULL) {
1199 			if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1200 					EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1201 			    EXT2_SB(sb)->s_es->s_rev_level ==
1202 					cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1203 			       /* If this is the first large file
1204 				* created, add a flag to the superblock.
1205 				*/
1206 				lock_kernel();
1207 				ext2_update_dynamic_rev(sb);
1208 				EXT2_SET_RO_COMPAT_FEATURE(sb,
1209 					EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1210 				unlock_kernel();
1211 				ext2_write_super(sb);
1212 			}
1213 		}
1214 	}
1215 
1216 	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1217 	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1218 		if (old_valid_dev(inode->i_rdev)) {
1219 			raw_inode->i_block[0] =
1220 				cpu_to_le32(old_encode_dev(inode->i_rdev));
1221 			raw_inode->i_block[1] = 0;
1222 		} else {
1223 			raw_inode->i_block[0] = 0;
1224 			raw_inode->i_block[1] =
1225 				cpu_to_le32(new_encode_dev(inode->i_rdev));
1226 			raw_inode->i_block[2] = 0;
1227 		}
1228 	} else for (n = 0; n < EXT2_N_BLOCKS; n++)
1229 		raw_inode->i_block[n] = ei->i_data[n];
1230 	mark_buffer_dirty(bh);
1231 	if (do_sync) {
1232 		sync_dirty_buffer(bh);
1233 		if (buffer_req(bh) && !buffer_uptodate(bh)) {
1234 			printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1235 				sb->s_id, (unsigned long) ino);
1236 			err = -EIO;
1237 		}
1238 	}
1239 	ei->i_state &= ~EXT2_STATE_NEW;
1240 	brelse (bh);
1241 	return err;
1242 }
1243 
1244 int ext2_write_inode(struct inode *inode, int wait)
1245 {
1246 	return ext2_update_inode(inode, wait);
1247 }
1248 
1249 int ext2_sync_inode(struct inode *inode)
1250 {
1251 	struct writeback_control wbc = {
1252 		.sync_mode = WB_SYNC_ALL,
1253 		.nr_to_write = 0,	/* sys_fsync did this */
1254 	};
1255 	return sync_inode(inode, &wbc);
1256 }
1257 
1258 int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1259 {
1260 	struct inode *inode = dentry->d_inode;
1261 	int error;
1262 
1263 	error = inode_change_ok(inode, iattr);
1264 	if (error)
1265 		return error;
1266 	if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||
1267 	    (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {
1268 		error = DQUOT_TRANSFER(inode, iattr) ? -EDQUOT : 0;
1269 		if (error)
1270 			return error;
1271 	}
1272 	error = inode_setattr(inode, iattr);
1273 	if (!error && (iattr->ia_valid & ATTR_MODE))
1274 		error = ext2_acl_chmod(inode);
1275 	return error;
1276 }
1277