xref: /openbmc/linux/fs/ext2/inode.c (revision 9ac8d3fb)
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 <linux/fiemap.h>
35 #include "ext2.h"
36 #include "acl.h"
37 #include "xip.h"
38 
39 MODULE_AUTHOR("Remy Card and others");
40 MODULE_DESCRIPTION("Second Extended Filesystem");
41 MODULE_LICENSE("GPL");
42 
43 static int ext2_update_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 /*
58  * Called at the last iput() if i_nlink is zero.
59  */
60 void ext2_delete_inode (struct inode * inode)
61 {
62 	truncate_inode_pages(&inode->i_data, 0);
63 
64 	if (is_bad_inode(inode))
65 		goto no_delete;
66 	EXT2_I(inode)->i_dtime	= get_seconds();
67 	mark_inode_dirty(inode);
68 	ext2_update_inode(inode, inode_needs_sync(inode));
69 
70 	inode->i_size = 0;
71 	if (inode->i_blocks)
72 		ext2_truncate (inode);
73 	ext2_free_inode (inode);
74 
75 	return;
76 no_delete:
77 	clear_inode(inode);	/* We must guarantee clearing of inode... */
78 }
79 
80 typedef struct {
81 	__le32	*p;
82 	__le32	key;
83 	struct buffer_head *bh;
84 } Indirect;
85 
86 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
87 {
88 	p->key = *(p->p = v);
89 	p->bh = bh;
90 }
91 
92 static inline int verify_chain(Indirect *from, Indirect *to)
93 {
94 	while (from <= to && from->key == *from->p)
95 		from++;
96 	return (from > to);
97 }
98 
99 /**
100  *	ext2_block_to_path - parse the block number into array of offsets
101  *	@inode: inode in question (we are only interested in its superblock)
102  *	@i_block: block number to be parsed
103  *	@offsets: array to store the offsets in
104  *      @boundary: set this non-zero if the referred-to block is likely to be
105  *             followed (on disk) by an indirect block.
106  *	To store the locations of file's data ext2 uses a data structure common
107  *	for UNIX filesystems - tree of pointers anchored in the inode, with
108  *	data blocks at leaves and indirect blocks in intermediate nodes.
109  *	This function translates the block number into path in that tree -
110  *	return value is the path length and @offsets[n] is the offset of
111  *	pointer to (n+1)th node in the nth one. If @block is out of range
112  *	(negative or too large) warning is printed and zero returned.
113  *
114  *	Note: function doesn't find node addresses, so no IO is needed. All
115  *	we need to know is the capacity of indirect blocks (taken from the
116  *	inode->i_sb).
117  */
118 
119 /*
120  * Portability note: the last comparison (check that we fit into triple
121  * indirect block) is spelled differently, because otherwise on an
122  * architecture with 32-bit longs and 8Kb pages we might get into trouble
123  * if our filesystem had 8Kb blocks. We might use long long, but that would
124  * kill us on x86. Oh, well, at least the sign propagation does not matter -
125  * i_block would have to be negative in the very beginning, so we would not
126  * get there at all.
127  */
128 
129 static int ext2_block_to_path(struct inode *inode,
130 			long i_block, int offsets[4], int *boundary)
131 {
132 	int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
133 	int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
134 	const long direct_blocks = EXT2_NDIR_BLOCKS,
135 		indirect_blocks = ptrs,
136 		double_blocks = (1 << (ptrs_bits * 2));
137 	int n = 0;
138 	int final = 0;
139 
140 	if (i_block < 0) {
141 		ext2_warning (inode->i_sb, "ext2_block_to_path", "block < 0");
142 	} else if (i_block < direct_blocks) {
143 		offsets[n++] = i_block;
144 		final = direct_blocks;
145 	} else if ( (i_block -= direct_blocks) < indirect_blocks) {
146 		offsets[n++] = EXT2_IND_BLOCK;
147 		offsets[n++] = i_block;
148 		final = ptrs;
149 	} else if ((i_block -= indirect_blocks) < double_blocks) {
150 		offsets[n++] = EXT2_DIND_BLOCK;
151 		offsets[n++] = i_block >> ptrs_bits;
152 		offsets[n++] = i_block & (ptrs - 1);
153 		final = ptrs;
154 	} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
155 		offsets[n++] = EXT2_TIND_BLOCK;
156 		offsets[n++] = i_block >> (ptrs_bits * 2);
157 		offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
158 		offsets[n++] = i_block & (ptrs - 1);
159 		final = ptrs;
160 	} else {
161 		ext2_warning (inode->i_sb, "ext2_block_to_path", "block > big");
162 	}
163 	if (boundary)
164 		*boundary = final - 1 - (i_block & (ptrs - 1));
165 
166 	return n;
167 }
168 
169 /**
170  *	ext2_get_branch - read the chain of indirect blocks leading to data
171  *	@inode: inode in question
172  *	@depth: depth of the chain (1 - direct pointer, etc.)
173  *	@offsets: offsets of pointers in inode/indirect blocks
174  *	@chain: place to store the result
175  *	@err: here we store the error value
176  *
177  *	Function fills the array of triples <key, p, bh> and returns %NULL
178  *	if everything went OK or the pointer to the last filled triple
179  *	(incomplete one) otherwise. Upon the return chain[i].key contains
180  *	the number of (i+1)-th block in the chain (as it is stored in memory,
181  *	i.e. little-endian 32-bit), chain[i].p contains the address of that
182  *	number (it points into struct inode for i==0 and into the bh->b_data
183  *	for i>0) and chain[i].bh points to the buffer_head of i-th indirect
184  *	block for i>0 and NULL for i==0. In other words, it holds the block
185  *	numbers of the chain, addresses they were taken from (and where we can
186  *	verify that chain did not change) and buffer_heads hosting these
187  *	numbers.
188  *
189  *	Function stops when it stumbles upon zero pointer (absent block)
190  *		(pointer to last triple returned, *@err == 0)
191  *	or when it gets an IO error reading an indirect block
192  *		(ditto, *@err == -EIO)
193  *	or when it notices that chain had been changed while it was reading
194  *		(ditto, *@err == -EAGAIN)
195  *	or when it reads all @depth-1 indirect blocks successfully and finds
196  *	the whole chain, all way to the data (returns %NULL, *err == 0).
197  */
198 static Indirect *ext2_get_branch(struct inode *inode,
199 				 int depth,
200 				 int *offsets,
201 				 Indirect chain[4],
202 				 int *err)
203 {
204 	struct super_block *sb = inode->i_sb;
205 	Indirect *p = chain;
206 	struct buffer_head *bh;
207 
208 	*err = 0;
209 	/* i_data is not going away, no lock needed */
210 	add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
211 	if (!p->key)
212 		goto no_block;
213 	while (--depth) {
214 		bh = sb_bread(sb, le32_to_cpu(p->key));
215 		if (!bh)
216 			goto failure;
217 		read_lock(&EXT2_I(inode)->i_meta_lock);
218 		if (!verify_chain(chain, p))
219 			goto changed;
220 		add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
221 		read_unlock(&EXT2_I(inode)->i_meta_lock);
222 		if (!p->key)
223 			goto no_block;
224 	}
225 	return NULL;
226 
227 changed:
228 	read_unlock(&EXT2_I(inode)->i_meta_lock);
229 	brelse(bh);
230 	*err = -EAGAIN;
231 	goto no_block;
232 failure:
233 	*err = -EIO;
234 no_block:
235 	return p;
236 }
237 
238 /**
239  *	ext2_find_near - find a place for allocation with sufficient locality
240  *	@inode: owner
241  *	@ind: descriptor of indirect block.
242  *
243  *	This function returns the preferred place for block allocation.
244  *	It is used when heuristic for sequential allocation fails.
245  *	Rules are:
246  *	  + if there is a block to the left of our position - allocate near it.
247  *	  + if pointer will live in indirect block - allocate near that block.
248  *	  + if pointer will live in inode - allocate in the same cylinder group.
249  *
250  * In the latter case we colour the starting block by the callers PID to
251  * prevent it from clashing with concurrent allocations for a different inode
252  * in the same block group.   The PID is used here so that functionally related
253  * files will be close-by on-disk.
254  *
255  *	Caller must make sure that @ind is valid and will stay that way.
256  */
257 
258 static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
259 {
260 	struct ext2_inode_info *ei = EXT2_I(inode);
261 	__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
262 	__le32 *p;
263 	ext2_fsblk_t bg_start;
264 	ext2_fsblk_t colour;
265 
266 	/* Try to find previous block */
267 	for (p = ind->p - 1; p >= start; p--)
268 		if (*p)
269 			return le32_to_cpu(*p);
270 
271 	/* No such thing, so let's try location of indirect block */
272 	if (ind->bh)
273 		return ind->bh->b_blocknr;
274 
275 	/*
276 	 * It is going to be refered from inode itself? OK, just put it into
277 	 * the same cylinder group then.
278 	 */
279 	bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
280 	colour = (current->pid % 16) *
281 			(EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
282 	return bg_start + colour;
283 }
284 
285 /**
286  *	ext2_find_goal - find a preferred place for allocation.
287  *	@inode: owner
288  *	@block:  block we want
289  *	@partial: pointer to the last triple within a chain
290  *
291  *	Returns preferred place for a block (the goal).
292  */
293 
294 static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,
295 					  Indirect *partial)
296 {
297 	struct ext2_block_alloc_info *block_i;
298 
299 	block_i = EXT2_I(inode)->i_block_alloc_info;
300 
301 	/*
302 	 * try the heuristic for sequential allocation,
303 	 * failing that at least try to get decent locality.
304 	 */
305 	if (block_i && (block == block_i->last_alloc_logical_block + 1)
306 		&& (block_i->last_alloc_physical_block != 0)) {
307 		return block_i->last_alloc_physical_block + 1;
308 	}
309 
310 	return ext2_find_near(inode, partial);
311 }
312 
313 /**
314  *	ext2_blks_to_allocate: Look up the block map and count the number
315  *	of direct blocks need to be allocated for the given branch.
316  *
317  * 	@branch: chain of indirect blocks
318  *	@k: number of blocks need for indirect blocks
319  *	@blks: number of data blocks to be mapped.
320  *	@blocks_to_boundary:  the offset in the indirect block
321  *
322  *	return the total number of blocks to be allocate, including the
323  *	direct and indirect blocks.
324  */
325 static int
326 ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
327 		int blocks_to_boundary)
328 {
329 	unsigned long count = 0;
330 
331 	/*
332 	 * Simple case, [t,d]Indirect block(s) has not allocated yet
333 	 * then it's clear blocks on that path have not allocated
334 	 */
335 	if (k > 0) {
336 		/* right now don't hanel cross boundary allocation */
337 		if (blks < blocks_to_boundary + 1)
338 			count += blks;
339 		else
340 			count += blocks_to_boundary + 1;
341 		return count;
342 	}
343 
344 	count++;
345 	while (count < blks && count <= blocks_to_boundary
346 		&& le32_to_cpu(*(branch[0].p + count)) == 0) {
347 		count++;
348 	}
349 	return count;
350 }
351 
352 /**
353  *	ext2_alloc_blocks: multiple allocate blocks needed for a branch
354  *	@indirect_blks: the number of blocks need to allocate for indirect
355  *			blocks
356  *
357  *	@new_blocks: on return it will store the new block numbers for
358  *	the indirect blocks(if needed) and the first direct block,
359  *	@blks:	on return it will store the total number of allocated
360  *		direct blocks
361  */
362 static int ext2_alloc_blocks(struct inode *inode,
363 			ext2_fsblk_t goal, int indirect_blks, int blks,
364 			ext2_fsblk_t new_blocks[4], int *err)
365 {
366 	int target, i;
367 	unsigned long count = 0;
368 	int index = 0;
369 	ext2_fsblk_t current_block = 0;
370 	int ret = 0;
371 
372 	/*
373 	 * Here we try to allocate the requested multiple blocks at once,
374 	 * on a best-effort basis.
375 	 * To build a branch, we should allocate blocks for
376 	 * the indirect blocks(if not allocated yet), and at least
377 	 * the first direct block of this branch.  That's the
378 	 * minimum number of blocks need to allocate(required)
379 	 */
380 	target = blks + indirect_blks;
381 
382 	while (1) {
383 		count = target;
384 		/* allocating blocks for indirect blocks and direct blocks */
385 		current_block = ext2_new_blocks(inode,goal,&count,err);
386 		if (*err)
387 			goto failed_out;
388 
389 		target -= count;
390 		/* allocate blocks for indirect blocks */
391 		while (index < indirect_blks && count) {
392 			new_blocks[index++] = current_block++;
393 			count--;
394 		}
395 
396 		if (count > 0)
397 			break;
398 	}
399 
400 	/* save the new block number for the first direct block */
401 	new_blocks[index] = current_block;
402 
403 	/* total number of blocks allocated for direct blocks */
404 	ret = count;
405 	*err = 0;
406 	return ret;
407 failed_out:
408 	for (i = 0; i <index; i++)
409 		ext2_free_blocks(inode, new_blocks[i], 1);
410 	return ret;
411 }
412 
413 /**
414  *	ext2_alloc_branch - allocate and set up a chain of blocks.
415  *	@inode: owner
416  *	@num: depth of the chain (number of blocks to allocate)
417  *	@offsets: offsets (in the blocks) to store the pointers to next.
418  *	@branch: place to store the chain in.
419  *
420  *	This function allocates @num blocks, zeroes out all but the last one,
421  *	links them into chain and (if we are synchronous) writes them to disk.
422  *	In other words, it prepares a branch that can be spliced onto the
423  *	inode. It stores the information about that chain in the branch[], in
424  *	the same format as ext2_get_branch() would do. We are calling it after
425  *	we had read the existing part of chain and partial points to the last
426  *	triple of that (one with zero ->key). Upon the exit we have the same
427  *	picture as after the successful ext2_get_block(), excpet that in one
428  *	place chain is disconnected - *branch->p is still zero (we did not
429  *	set the last link), but branch->key contains the number that should
430  *	be placed into *branch->p to fill that gap.
431  *
432  *	If allocation fails we free all blocks we've allocated (and forget
433  *	their buffer_heads) and return the error value the from failed
434  *	ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
435  *	as described above and return 0.
436  */
437 
438 static int ext2_alloc_branch(struct inode *inode,
439 			int indirect_blks, int *blks, ext2_fsblk_t goal,
440 			int *offsets, Indirect *branch)
441 {
442 	int blocksize = inode->i_sb->s_blocksize;
443 	int i, n = 0;
444 	int err = 0;
445 	struct buffer_head *bh;
446 	int num;
447 	ext2_fsblk_t new_blocks[4];
448 	ext2_fsblk_t current_block;
449 
450 	num = ext2_alloc_blocks(inode, goal, indirect_blks,
451 				*blks, new_blocks, &err);
452 	if (err)
453 		return err;
454 
455 	branch[0].key = cpu_to_le32(new_blocks[0]);
456 	/*
457 	 * metadata blocks and data blocks are allocated.
458 	 */
459 	for (n = 1; n <= indirect_blks;  n++) {
460 		/*
461 		 * Get buffer_head for parent block, zero it out
462 		 * and set the pointer to new one, then send
463 		 * parent to disk.
464 		 */
465 		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
466 		branch[n].bh = bh;
467 		lock_buffer(bh);
468 		memset(bh->b_data, 0, blocksize);
469 		branch[n].p = (__le32 *) bh->b_data + offsets[n];
470 		branch[n].key = cpu_to_le32(new_blocks[n]);
471 		*branch[n].p = branch[n].key;
472 		if ( n == indirect_blks) {
473 			current_block = new_blocks[n];
474 			/*
475 			 * End of chain, update the last new metablock of
476 			 * the chain to point to the new allocated
477 			 * data blocks numbers
478 			 */
479 			for (i=1; i < num; i++)
480 				*(branch[n].p + i) = cpu_to_le32(++current_block);
481 		}
482 		set_buffer_uptodate(bh);
483 		unlock_buffer(bh);
484 		mark_buffer_dirty_inode(bh, inode);
485 		/* We used to sync bh here if IS_SYNC(inode).
486 		 * But we now rely upon generic_osync_inode()
487 		 * and b_inode_buffers.  But not for directories.
488 		 */
489 		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
490 			sync_dirty_buffer(bh);
491 	}
492 	*blks = num;
493 	return err;
494 }
495 
496 /**
497  * ext2_splice_branch - splice the allocated branch onto inode.
498  * @inode: owner
499  * @block: (logical) number of block we are adding
500  * @chain: chain of indirect blocks (with a missing link - see
501  *	ext2_alloc_branch)
502  * @where: location of missing link
503  * @num:   number of indirect blocks we are adding
504  * @blks:  number of direct blocks we are adding
505  *
506  * This function fills the missing link and does all housekeeping needed in
507  * inode (->i_blocks, etc.). In case of success we end up with the full
508  * chain to new block and return 0.
509  */
510 static void ext2_splice_branch(struct inode *inode,
511 			long block, Indirect *where, int num, int blks)
512 {
513 	int i;
514 	struct ext2_block_alloc_info *block_i;
515 	ext2_fsblk_t current_block;
516 
517 	block_i = EXT2_I(inode)->i_block_alloc_info;
518 
519 	/* XXX LOCKING probably should have i_meta_lock ?*/
520 	/* That's it */
521 
522 	*where->p = where->key;
523 
524 	/*
525 	 * Update the host buffer_head or inode to point to more just allocated
526 	 * direct blocks blocks
527 	 */
528 	if (num == 0 && blks > 1) {
529 		current_block = le32_to_cpu(where->key) + 1;
530 		for (i = 1; i < blks; i++)
531 			*(where->p + i ) = cpu_to_le32(current_block++);
532 	}
533 
534 	/*
535 	 * update the most recently allocated logical & physical block
536 	 * in i_block_alloc_info, to assist find the proper goal block for next
537 	 * allocation
538 	 */
539 	if (block_i) {
540 		block_i->last_alloc_logical_block = block + blks - 1;
541 		block_i->last_alloc_physical_block =
542 				le32_to_cpu(where[num].key) + blks - 1;
543 	}
544 
545 	/* We are done with atomic stuff, now do the rest of housekeeping */
546 
547 	/* had we spliced it onto indirect block? */
548 	if (where->bh)
549 		mark_buffer_dirty_inode(where->bh, inode);
550 
551 	inode->i_ctime = CURRENT_TIME_SEC;
552 	mark_inode_dirty(inode);
553 }
554 
555 /*
556  * Allocation strategy is simple: if we have to allocate something, we will
557  * have to go the whole way to leaf. So let's do it before attaching anything
558  * to tree, set linkage between the newborn blocks, write them if sync is
559  * required, recheck the path, free and repeat if check fails, otherwise
560  * set the last missing link (that will protect us from any truncate-generated
561  * removals - all blocks on the path are immune now) and possibly force the
562  * write on the parent block.
563  * That has a nice additional property: no special recovery from the failed
564  * allocations is needed - we simply release blocks and do not touch anything
565  * reachable from inode.
566  *
567  * `handle' can be NULL if create == 0.
568  *
569  * return > 0, # of blocks mapped or allocated.
570  * return = 0, if plain lookup failed.
571  * return < 0, error case.
572  */
573 static int ext2_get_blocks(struct inode *inode,
574 			   sector_t iblock, unsigned long maxblocks,
575 			   struct buffer_head *bh_result,
576 			   int create)
577 {
578 	int err = -EIO;
579 	int offsets[4];
580 	Indirect chain[4];
581 	Indirect *partial;
582 	ext2_fsblk_t goal;
583 	int indirect_blks;
584 	int blocks_to_boundary = 0;
585 	int depth;
586 	struct ext2_inode_info *ei = EXT2_I(inode);
587 	int count = 0;
588 	ext2_fsblk_t first_block = 0;
589 
590 	depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
591 
592 	if (depth == 0)
593 		return (err);
594 reread:
595 	partial = ext2_get_branch(inode, depth, offsets, chain, &err);
596 
597 	/* Simplest case - block found, no allocation needed */
598 	if (!partial) {
599 		first_block = le32_to_cpu(chain[depth - 1].key);
600 		clear_buffer_new(bh_result); /* What's this do? */
601 		count++;
602 		/*map more blocks*/
603 		while (count < maxblocks && count <= blocks_to_boundary) {
604 			ext2_fsblk_t blk;
605 
606 			if (!verify_chain(chain, partial)) {
607 				/*
608 				 * Indirect block might be removed by
609 				 * truncate while we were reading it.
610 				 * Handling of that case: forget what we've
611 				 * got now, go to reread.
612 				 */
613 				count = 0;
614 				goto changed;
615 			}
616 			blk = le32_to_cpu(*(chain[depth-1].p + count));
617 			if (blk == first_block + count)
618 				count++;
619 			else
620 				break;
621 		}
622 		goto got_it;
623 	}
624 
625 	/* Next simple case - plain lookup or failed read of indirect block */
626 	if (!create || err == -EIO)
627 		goto cleanup;
628 
629 	mutex_lock(&ei->truncate_mutex);
630 
631 	/*
632 	 * Okay, we need to do block allocation.  Lazily initialize the block
633 	 * allocation info here if necessary
634 	*/
635 	if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
636 		ext2_init_block_alloc_info(inode);
637 
638 	goal = ext2_find_goal(inode, iblock, partial);
639 
640 	/* the number of blocks need to allocate for [d,t]indirect blocks */
641 	indirect_blks = (chain + depth) - partial - 1;
642 	/*
643 	 * Next look up the indirect map to count the totoal number of
644 	 * direct blocks to allocate for this branch.
645 	 */
646 	count = ext2_blks_to_allocate(partial, indirect_blks,
647 					maxblocks, blocks_to_boundary);
648 	/*
649 	 * XXX ???? Block out ext2_truncate while we alter the tree
650 	 */
651 	err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
652 				offsets + (partial - chain), partial);
653 
654 	if (err) {
655 		mutex_unlock(&ei->truncate_mutex);
656 		goto cleanup;
657 	}
658 
659 	if (ext2_use_xip(inode->i_sb)) {
660 		/*
661 		 * we need to clear the block
662 		 */
663 		err = ext2_clear_xip_target (inode,
664 			le32_to_cpu(chain[depth-1].key));
665 		if (err) {
666 			mutex_unlock(&ei->truncate_mutex);
667 			goto cleanup;
668 		}
669 	}
670 
671 	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
672 	mutex_unlock(&ei->truncate_mutex);
673 	set_buffer_new(bh_result);
674 got_it:
675 	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
676 	if (count > blocks_to_boundary)
677 		set_buffer_boundary(bh_result);
678 	err = count;
679 	/* Clean up and exit */
680 	partial = chain + depth - 1;	/* the whole chain */
681 cleanup:
682 	while (partial > chain) {
683 		brelse(partial->bh);
684 		partial--;
685 	}
686 	return err;
687 changed:
688 	while (partial > chain) {
689 		brelse(partial->bh);
690 		partial--;
691 	}
692 	goto reread;
693 }
694 
695 int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
696 {
697 	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
698 	int ret = ext2_get_blocks(inode, iblock, max_blocks,
699 			      bh_result, create);
700 	if (ret > 0) {
701 		bh_result->b_size = (ret << inode->i_blkbits);
702 		ret = 0;
703 	}
704 	return ret;
705 
706 }
707 
708 int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
709 		u64 start, u64 len)
710 {
711 	return generic_block_fiemap(inode, fieinfo, start, len,
712 				    ext2_get_block);
713 }
714 
715 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
716 {
717 	return block_write_full_page(page, ext2_get_block, wbc);
718 }
719 
720 static int ext2_readpage(struct file *file, struct page *page)
721 {
722 	return mpage_readpage(page, ext2_get_block);
723 }
724 
725 static int
726 ext2_readpages(struct file *file, struct address_space *mapping,
727 		struct list_head *pages, unsigned nr_pages)
728 {
729 	return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
730 }
731 
732 int __ext2_write_begin(struct file *file, struct address_space *mapping,
733 		loff_t pos, unsigned len, unsigned flags,
734 		struct page **pagep, void **fsdata)
735 {
736 	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
737 							ext2_get_block);
738 }
739 
740 static int
741 ext2_write_begin(struct file *file, struct address_space *mapping,
742 		loff_t pos, unsigned len, unsigned flags,
743 		struct page **pagep, void **fsdata)
744 {
745 	*pagep = NULL;
746 	return __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
747 }
748 
749 static int
750 ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
751 		loff_t pos, unsigned len, unsigned flags,
752 		struct page **pagep, void **fsdata)
753 {
754 	/*
755 	 * Dir-in-pagecache still uses ext2_write_begin. Would have to rework
756 	 * directory handling code to pass around offsets rather than struct
757 	 * pages in order to make this work easily.
758 	 */
759 	return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
760 							ext2_get_block);
761 }
762 
763 static int ext2_nobh_writepage(struct page *page,
764 			struct writeback_control *wbc)
765 {
766 	return nobh_writepage(page, ext2_get_block, wbc);
767 }
768 
769 static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
770 {
771 	return generic_block_bmap(mapping,block,ext2_get_block);
772 }
773 
774 static ssize_t
775 ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
776 			loff_t offset, unsigned long nr_segs)
777 {
778 	struct file *file = iocb->ki_filp;
779 	struct inode *inode = file->f_mapping->host;
780 
781 	return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
782 				offset, nr_segs, ext2_get_block, NULL);
783 }
784 
785 static int
786 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
787 {
788 	return mpage_writepages(mapping, wbc, ext2_get_block);
789 }
790 
791 const struct address_space_operations ext2_aops = {
792 	.readpage		= ext2_readpage,
793 	.readpages		= ext2_readpages,
794 	.writepage		= ext2_writepage,
795 	.sync_page		= block_sync_page,
796 	.write_begin		= ext2_write_begin,
797 	.write_end		= generic_write_end,
798 	.bmap			= ext2_bmap,
799 	.direct_IO		= ext2_direct_IO,
800 	.writepages		= ext2_writepages,
801 	.migratepage		= buffer_migrate_page,
802 	.is_partially_uptodate	= block_is_partially_uptodate,
803 };
804 
805 const struct address_space_operations ext2_aops_xip = {
806 	.bmap			= ext2_bmap,
807 	.get_xip_mem		= ext2_get_xip_mem,
808 };
809 
810 const struct address_space_operations ext2_nobh_aops = {
811 	.readpage		= ext2_readpage,
812 	.readpages		= ext2_readpages,
813 	.writepage		= ext2_nobh_writepage,
814 	.sync_page		= block_sync_page,
815 	.write_begin		= ext2_nobh_write_begin,
816 	.write_end		= nobh_write_end,
817 	.bmap			= ext2_bmap,
818 	.direct_IO		= ext2_direct_IO,
819 	.writepages		= ext2_writepages,
820 	.migratepage		= buffer_migrate_page,
821 };
822 
823 /*
824  * Probably it should be a library function... search for first non-zero word
825  * or memcmp with zero_page, whatever is better for particular architecture.
826  * Linus?
827  */
828 static inline int all_zeroes(__le32 *p, __le32 *q)
829 {
830 	while (p < q)
831 		if (*p++)
832 			return 0;
833 	return 1;
834 }
835 
836 /**
837  *	ext2_find_shared - find the indirect blocks for partial truncation.
838  *	@inode:	  inode in question
839  *	@depth:	  depth of the affected branch
840  *	@offsets: offsets of pointers in that branch (see ext2_block_to_path)
841  *	@chain:	  place to store the pointers to partial indirect blocks
842  *	@top:	  place to the (detached) top of branch
843  *
844  *	This is a helper function used by ext2_truncate().
845  *
846  *	When we do truncate() we may have to clean the ends of several indirect
847  *	blocks but leave the blocks themselves alive. Block is partially
848  *	truncated if some data below the new i_size is refered from it (and
849  *	it is on the path to the first completely truncated data block, indeed).
850  *	We have to free the top of that path along with everything to the right
851  *	of the path. Since no allocation past the truncation point is possible
852  *	until ext2_truncate() finishes, we may safely do the latter, but top
853  *	of branch may require special attention - pageout below the truncation
854  *	point might try to populate it.
855  *
856  *	We atomically detach the top of branch from the tree, store the block
857  *	number of its root in *@top, pointers to buffer_heads of partially
858  *	truncated blocks - in @chain[].bh and pointers to their last elements
859  *	that should not be removed - in @chain[].p. Return value is the pointer
860  *	to last filled element of @chain.
861  *
862  *	The work left to caller to do the actual freeing of subtrees:
863  *		a) free the subtree starting from *@top
864  *		b) free the subtrees whose roots are stored in
865  *			(@chain[i].p+1 .. end of @chain[i].bh->b_data)
866  *		c) free the subtrees growing from the inode past the @chain[0].p
867  *			(no partially truncated stuff there).
868  */
869 
870 static Indirect *ext2_find_shared(struct inode *inode,
871 				int depth,
872 				int offsets[4],
873 				Indirect chain[4],
874 				__le32 *top)
875 {
876 	Indirect *partial, *p;
877 	int k, err;
878 
879 	*top = 0;
880 	for (k = depth; k > 1 && !offsets[k-1]; k--)
881 		;
882 	partial = ext2_get_branch(inode, k, offsets, chain, &err);
883 	if (!partial)
884 		partial = chain + k-1;
885 	/*
886 	 * If the branch acquired continuation since we've looked at it -
887 	 * fine, it should all survive and (new) top doesn't belong to us.
888 	 */
889 	write_lock(&EXT2_I(inode)->i_meta_lock);
890 	if (!partial->key && *partial->p) {
891 		write_unlock(&EXT2_I(inode)->i_meta_lock);
892 		goto no_top;
893 	}
894 	for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
895 		;
896 	/*
897 	 * OK, we've found the last block that must survive. The rest of our
898 	 * branch should be detached before unlocking. However, if that rest
899 	 * of branch is all ours and does not grow immediately from the inode
900 	 * it's easier to cheat and just decrement partial->p.
901 	 */
902 	if (p == chain + k - 1 && p > chain) {
903 		p->p--;
904 	} else {
905 		*top = *p->p;
906 		*p->p = 0;
907 	}
908 	write_unlock(&EXT2_I(inode)->i_meta_lock);
909 
910 	while(partial > p)
911 	{
912 		brelse(partial->bh);
913 		partial--;
914 	}
915 no_top:
916 	return partial;
917 }
918 
919 /**
920  *	ext2_free_data - free a list of data blocks
921  *	@inode:	inode we are dealing with
922  *	@p:	array of block numbers
923  *	@q:	points immediately past the end of array
924  *
925  *	We are freeing all blocks refered from that array (numbers are
926  *	stored as little-endian 32-bit) and updating @inode->i_blocks
927  *	appropriately.
928  */
929 static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
930 {
931 	unsigned long block_to_free = 0, count = 0;
932 	unsigned long nr;
933 
934 	for ( ; p < q ; p++) {
935 		nr = le32_to_cpu(*p);
936 		if (nr) {
937 			*p = 0;
938 			/* accumulate blocks to free if they're contiguous */
939 			if (count == 0)
940 				goto free_this;
941 			else if (block_to_free == nr - count)
942 				count++;
943 			else {
944 				mark_inode_dirty(inode);
945 				ext2_free_blocks (inode, block_to_free, count);
946 			free_this:
947 				block_to_free = nr;
948 				count = 1;
949 			}
950 		}
951 	}
952 	if (count > 0) {
953 		mark_inode_dirty(inode);
954 		ext2_free_blocks (inode, block_to_free, count);
955 	}
956 }
957 
958 /**
959  *	ext2_free_branches - free an array of branches
960  *	@inode:	inode we are dealing with
961  *	@p:	array of block numbers
962  *	@q:	pointer immediately past the end of array
963  *	@depth:	depth of the branches to free
964  *
965  *	We are freeing all blocks refered from these branches (numbers are
966  *	stored as little-endian 32-bit) and updating @inode->i_blocks
967  *	appropriately.
968  */
969 static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
970 {
971 	struct buffer_head * bh;
972 	unsigned long nr;
973 
974 	if (depth--) {
975 		int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
976 		for ( ; p < q ; p++) {
977 			nr = le32_to_cpu(*p);
978 			if (!nr)
979 				continue;
980 			*p = 0;
981 			bh = sb_bread(inode->i_sb, nr);
982 			/*
983 			 * A read failure? Report error and clear slot
984 			 * (should be rare).
985 			 */
986 			if (!bh) {
987 				ext2_error(inode->i_sb, "ext2_free_branches",
988 					"Read failure, inode=%ld, block=%ld",
989 					inode->i_ino, nr);
990 				continue;
991 			}
992 			ext2_free_branches(inode,
993 					   (__le32*)bh->b_data,
994 					   (__le32*)bh->b_data + addr_per_block,
995 					   depth);
996 			bforget(bh);
997 			ext2_free_blocks(inode, nr, 1);
998 			mark_inode_dirty(inode);
999 		}
1000 	} else
1001 		ext2_free_data(inode, p, q);
1002 }
1003 
1004 void ext2_truncate(struct inode *inode)
1005 {
1006 	__le32 *i_data = EXT2_I(inode)->i_data;
1007 	struct ext2_inode_info *ei = EXT2_I(inode);
1008 	int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1009 	int offsets[4];
1010 	Indirect chain[4];
1011 	Indirect *partial;
1012 	__le32 nr = 0;
1013 	int n;
1014 	long iblock;
1015 	unsigned blocksize;
1016 
1017 	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1018 	    S_ISLNK(inode->i_mode)))
1019 		return;
1020 	if (ext2_inode_is_fast_symlink(inode))
1021 		return;
1022 	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1023 		return;
1024 
1025 	blocksize = inode->i_sb->s_blocksize;
1026 	iblock = (inode->i_size + blocksize-1)
1027 					>> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
1028 
1029 	if (mapping_is_xip(inode->i_mapping))
1030 		xip_truncate_page(inode->i_mapping, inode->i_size);
1031 	else if (test_opt(inode->i_sb, NOBH))
1032 		nobh_truncate_page(inode->i_mapping,
1033 				inode->i_size, ext2_get_block);
1034 	else
1035 		block_truncate_page(inode->i_mapping,
1036 				inode->i_size, ext2_get_block);
1037 
1038 	n = ext2_block_to_path(inode, iblock, offsets, NULL);
1039 	if (n == 0)
1040 		return;
1041 
1042 	/*
1043 	 * From here we block out all ext2_get_block() callers who want to
1044 	 * modify the block allocation tree.
1045 	 */
1046 	mutex_lock(&ei->truncate_mutex);
1047 
1048 	if (n == 1) {
1049 		ext2_free_data(inode, i_data+offsets[0],
1050 					i_data + EXT2_NDIR_BLOCKS);
1051 		goto do_indirects;
1052 	}
1053 
1054 	partial = ext2_find_shared(inode, n, offsets, chain, &nr);
1055 	/* Kill the top of shared branch (already detached) */
1056 	if (nr) {
1057 		if (partial == chain)
1058 			mark_inode_dirty(inode);
1059 		else
1060 			mark_buffer_dirty_inode(partial->bh, inode);
1061 		ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
1062 	}
1063 	/* Clear the ends of indirect blocks on the shared branch */
1064 	while (partial > chain) {
1065 		ext2_free_branches(inode,
1066 				   partial->p + 1,
1067 				   (__le32*)partial->bh->b_data+addr_per_block,
1068 				   (chain+n-1) - partial);
1069 		mark_buffer_dirty_inode(partial->bh, inode);
1070 		brelse (partial->bh);
1071 		partial--;
1072 	}
1073 do_indirects:
1074 	/* Kill the remaining (whole) subtrees */
1075 	switch (offsets[0]) {
1076 		default:
1077 			nr = i_data[EXT2_IND_BLOCK];
1078 			if (nr) {
1079 				i_data[EXT2_IND_BLOCK] = 0;
1080 				mark_inode_dirty(inode);
1081 				ext2_free_branches(inode, &nr, &nr+1, 1);
1082 			}
1083 		case EXT2_IND_BLOCK:
1084 			nr = i_data[EXT2_DIND_BLOCK];
1085 			if (nr) {
1086 				i_data[EXT2_DIND_BLOCK] = 0;
1087 				mark_inode_dirty(inode);
1088 				ext2_free_branches(inode, &nr, &nr+1, 2);
1089 			}
1090 		case EXT2_DIND_BLOCK:
1091 			nr = i_data[EXT2_TIND_BLOCK];
1092 			if (nr) {
1093 				i_data[EXT2_TIND_BLOCK] = 0;
1094 				mark_inode_dirty(inode);
1095 				ext2_free_branches(inode, &nr, &nr+1, 3);
1096 			}
1097 		case EXT2_TIND_BLOCK:
1098 			;
1099 	}
1100 
1101 	ext2_discard_reservation(inode);
1102 
1103 	mutex_unlock(&ei->truncate_mutex);
1104 	inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
1105 	if (inode_needs_sync(inode)) {
1106 		sync_mapping_buffers(inode->i_mapping);
1107 		ext2_sync_inode (inode);
1108 	} else {
1109 		mark_inode_dirty(inode);
1110 	}
1111 }
1112 
1113 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
1114 					struct buffer_head **p)
1115 {
1116 	struct buffer_head * bh;
1117 	unsigned long block_group;
1118 	unsigned long block;
1119 	unsigned long offset;
1120 	struct ext2_group_desc * gdp;
1121 
1122 	*p = NULL;
1123 	if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
1124 	    ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
1125 		goto Einval;
1126 
1127 	block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
1128 	gdp = ext2_get_group_desc(sb, block_group, NULL);
1129 	if (!gdp)
1130 		goto Egdp;
1131 	/*
1132 	 * Figure out the offset within the block group inode table
1133 	 */
1134 	offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
1135 	block = le32_to_cpu(gdp->bg_inode_table) +
1136 		(offset >> EXT2_BLOCK_SIZE_BITS(sb));
1137 	if (!(bh = sb_bread(sb, block)))
1138 		goto Eio;
1139 
1140 	*p = bh;
1141 	offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1142 	return (struct ext2_inode *) (bh->b_data + offset);
1143 
1144 Einval:
1145 	ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1146 		   (unsigned long) ino);
1147 	return ERR_PTR(-EINVAL);
1148 Eio:
1149 	ext2_error(sb, "ext2_get_inode",
1150 		   "unable to read inode block - inode=%lu, block=%lu",
1151 		   (unsigned long) ino, block);
1152 Egdp:
1153 	return ERR_PTR(-EIO);
1154 }
1155 
1156 void ext2_set_inode_flags(struct inode *inode)
1157 {
1158 	unsigned int flags = EXT2_I(inode)->i_flags;
1159 
1160 	inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
1161 	if (flags & EXT2_SYNC_FL)
1162 		inode->i_flags |= S_SYNC;
1163 	if (flags & EXT2_APPEND_FL)
1164 		inode->i_flags |= S_APPEND;
1165 	if (flags & EXT2_IMMUTABLE_FL)
1166 		inode->i_flags |= S_IMMUTABLE;
1167 	if (flags & EXT2_NOATIME_FL)
1168 		inode->i_flags |= S_NOATIME;
1169 	if (flags & EXT2_DIRSYNC_FL)
1170 		inode->i_flags |= S_DIRSYNC;
1171 }
1172 
1173 /* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
1174 void ext2_get_inode_flags(struct ext2_inode_info *ei)
1175 {
1176 	unsigned int flags = ei->vfs_inode.i_flags;
1177 
1178 	ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
1179 			EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
1180 	if (flags & S_SYNC)
1181 		ei->i_flags |= EXT2_SYNC_FL;
1182 	if (flags & S_APPEND)
1183 		ei->i_flags |= EXT2_APPEND_FL;
1184 	if (flags & S_IMMUTABLE)
1185 		ei->i_flags |= EXT2_IMMUTABLE_FL;
1186 	if (flags & S_NOATIME)
1187 		ei->i_flags |= EXT2_NOATIME_FL;
1188 	if (flags & S_DIRSYNC)
1189 		ei->i_flags |= EXT2_DIRSYNC_FL;
1190 }
1191 
1192 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
1193 {
1194 	struct ext2_inode_info *ei;
1195 	struct buffer_head * bh;
1196 	struct ext2_inode *raw_inode;
1197 	struct inode *inode;
1198 	long ret = -EIO;
1199 	int n;
1200 
1201 	inode = iget_locked(sb, ino);
1202 	if (!inode)
1203 		return ERR_PTR(-ENOMEM);
1204 	if (!(inode->i_state & I_NEW))
1205 		return inode;
1206 
1207 	ei = EXT2_I(inode);
1208 #ifdef CONFIG_EXT2_FS_POSIX_ACL
1209 	ei->i_acl = EXT2_ACL_NOT_CACHED;
1210 	ei->i_default_acl = EXT2_ACL_NOT_CACHED;
1211 #endif
1212 	ei->i_block_alloc_info = NULL;
1213 
1214 	raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1215 	if (IS_ERR(raw_inode)) {
1216 		ret = PTR_ERR(raw_inode);
1217  		goto bad_inode;
1218 	}
1219 
1220 	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1221 	inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1222 	inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1223 	if (!(test_opt (inode->i_sb, NO_UID32))) {
1224 		inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1225 		inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1226 	}
1227 	inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
1228 	inode->i_size = le32_to_cpu(raw_inode->i_size);
1229 	inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
1230 	inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
1231 	inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
1232 	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1233 	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1234 	/* We now have enough fields to check if the inode was active or not.
1235 	 * This is needed because nfsd might try to access dead inodes
1236 	 * the test is that same one that e2fsck uses
1237 	 * NeilBrown 1999oct15
1238 	 */
1239 	if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1240 		/* this inode is deleted */
1241 		brelse (bh);
1242 		ret = -ESTALE;
1243 		goto bad_inode;
1244 	}
1245 	inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1246 	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1247 	ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1248 	ei->i_frag_no = raw_inode->i_frag;
1249 	ei->i_frag_size = raw_inode->i_fsize;
1250 	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1251 	ei->i_dir_acl = 0;
1252 	if (S_ISREG(inode->i_mode))
1253 		inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1254 	else
1255 		ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1256 	ei->i_dtime = 0;
1257 	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1258 	ei->i_state = 0;
1259 	ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1260 	ei->i_dir_start_lookup = 0;
1261 
1262 	/*
1263 	 * NOTE! The in-memory inode i_data array is in little-endian order
1264 	 * even on big-endian machines: we do NOT byteswap the block numbers!
1265 	 */
1266 	for (n = 0; n < EXT2_N_BLOCKS; n++)
1267 		ei->i_data[n] = raw_inode->i_block[n];
1268 
1269 	if (S_ISREG(inode->i_mode)) {
1270 		inode->i_op = &ext2_file_inode_operations;
1271 		if (ext2_use_xip(inode->i_sb)) {
1272 			inode->i_mapping->a_ops = &ext2_aops_xip;
1273 			inode->i_fop = &ext2_xip_file_operations;
1274 		} else if (test_opt(inode->i_sb, NOBH)) {
1275 			inode->i_mapping->a_ops = &ext2_nobh_aops;
1276 			inode->i_fop = &ext2_file_operations;
1277 		} else {
1278 			inode->i_mapping->a_ops = &ext2_aops;
1279 			inode->i_fop = &ext2_file_operations;
1280 		}
1281 	} else if (S_ISDIR(inode->i_mode)) {
1282 		inode->i_op = &ext2_dir_inode_operations;
1283 		inode->i_fop = &ext2_dir_operations;
1284 		if (test_opt(inode->i_sb, NOBH))
1285 			inode->i_mapping->a_ops = &ext2_nobh_aops;
1286 		else
1287 			inode->i_mapping->a_ops = &ext2_aops;
1288 	} else if (S_ISLNK(inode->i_mode)) {
1289 		if (ext2_inode_is_fast_symlink(inode))
1290 			inode->i_op = &ext2_fast_symlink_inode_operations;
1291 		else {
1292 			inode->i_op = &ext2_symlink_inode_operations;
1293 			if (test_opt(inode->i_sb, NOBH))
1294 				inode->i_mapping->a_ops = &ext2_nobh_aops;
1295 			else
1296 				inode->i_mapping->a_ops = &ext2_aops;
1297 		}
1298 	} else {
1299 		inode->i_op = &ext2_special_inode_operations;
1300 		if (raw_inode->i_block[0])
1301 			init_special_inode(inode, inode->i_mode,
1302 			   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1303 		else
1304 			init_special_inode(inode, inode->i_mode,
1305 			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1306 	}
1307 	brelse (bh);
1308 	ext2_set_inode_flags(inode);
1309 	unlock_new_inode(inode);
1310 	return inode;
1311 
1312 bad_inode:
1313 	iget_failed(inode);
1314 	return ERR_PTR(ret);
1315 }
1316 
1317 static int ext2_update_inode(struct inode * inode, int do_sync)
1318 {
1319 	struct ext2_inode_info *ei = EXT2_I(inode);
1320 	struct super_block *sb = inode->i_sb;
1321 	ino_t ino = inode->i_ino;
1322 	uid_t uid = inode->i_uid;
1323 	gid_t gid = inode->i_gid;
1324 	struct buffer_head * bh;
1325 	struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1326 	int n;
1327 	int err = 0;
1328 
1329 	if (IS_ERR(raw_inode))
1330  		return -EIO;
1331 
1332 	/* For fields not not tracking in the in-memory inode,
1333 	 * initialise them to zero for new inodes. */
1334 	if (ei->i_state & EXT2_STATE_NEW)
1335 		memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1336 
1337 	ext2_get_inode_flags(ei);
1338 	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1339 	if (!(test_opt(sb, NO_UID32))) {
1340 		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1341 		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1342 /*
1343  * Fix up interoperability with old kernels. Otherwise, old inodes get
1344  * re-used with the upper 16 bits of the uid/gid intact
1345  */
1346 		if (!ei->i_dtime) {
1347 			raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1348 			raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1349 		} else {
1350 			raw_inode->i_uid_high = 0;
1351 			raw_inode->i_gid_high = 0;
1352 		}
1353 	} else {
1354 		raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1355 		raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1356 		raw_inode->i_uid_high = 0;
1357 		raw_inode->i_gid_high = 0;
1358 	}
1359 	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1360 	raw_inode->i_size = cpu_to_le32(inode->i_size);
1361 	raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1362 	raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1363 	raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1364 
1365 	raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1366 	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1367 	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1368 	raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1369 	raw_inode->i_frag = ei->i_frag_no;
1370 	raw_inode->i_fsize = ei->i_frag_size;
1371 	raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1372 	if (!S_ISREG(inode->i_mode))
1373 		raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1374 	else {
1375 		raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1376 		if (inode->i_size > 0x7fffffffULL) {
1377 			if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1378 					EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1379 			    EXT2_SB(sb)->s_es->s_rev_level ==
1380 					cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1381 			       /* If this is the first large file
1382 				* created, add a flag to the superblock.
1383 				*/
1384 				lock_kernel();
1385 				ext2_update_dynamic_rev(sb);
1386 				EXT2_SET_RO_COMPAT_FEATURE(sb,
1387 					EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1388 				unlock_kernel();
1389 				ext2_write_super(sb);
1390 			}
1391 		}
1392 	}
1393 
1394 	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1395 	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1396 		if (old_valid_dev(inode->i_rdev)) {
1397 			raw_inode->i_block[0] =
1398 				cpu_to_le32(old_encode_dev(inode->i_rdev));
1399 			raw_inode->i_block[1] = 0;
1400 		} else {
1401 			raw_inode->i_block[0] = 0;
1402 			raw_inode->i_block[1] =
1403 				cpu_to_le32(new_encode_dev(inode->i_rdev));
1404 			raw_inode->i_block[2] = 0;
1405 		}
1406 	} else for (n = 0; n < EXT2_N_BLOCKS; n++)
1407 		raw_inode->i_block[n] = ei->i_data[n];
1408 	mark_buffer_dirty(bh);
1409 	if (do_sync) {
1410 		sync_dirty_buffer(bh);
1411 		if (buffer_req(bh) && !buffer_uptodate(bh)) {
1412 			printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1413 				sb->s_id, (unsigned long) ino);
1414 			err = -EIO;
1415 		}
1416 	}
1417 	ei->i_state &= ~EXT2_STATE_NEW;
1418 	brelse (bh);
1419 	return err;
1420 }
1421 
1422 int ext2_write_inode(struct inode *inode, int wait)
1423 {
1424 	return ext2_update_inode(inode, wait);
1425 }
1426 
1427 int ext2_sync_inode(struct inode *inode)
1428 {
1429 	struct writeback_control wbc = {
1430 		.sync_mode = WB_SYNC_ALL,
1431 		.nr_to_write = 0,	/* sys_fsync did this */
1432 	};
1433 	return sync_inode(inode, &wbc);
1434 }
1435 
1436 int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1437 {
1438 	struct inode *inode = dentry->d_inode;
1439 	int error;
1440 
1441 	error = inode_change_ok(inode, iattr);
1442 	if (error)
1443 		return error;
1444 	if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||
1445 	    (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {
1446 		error = DQUOT_TRANSFER(inode, iattr) ? -EDQUOT : 0;
1447 		if (error)
1448 			return error;
1449 	}
1450 	error = inode_setattr(inode, iattr);
1451 	if (!error && (iattr->ia_valid & ATTR_MODE))
1452 		error = ext2_acl_chmod(inode);
1453 	return error;
1454 }
1455