inode.c 155 KB
Newer Older
1
/*
2
 *  linux/fs/ext4/inode.c
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Goal-directed block allocation by Stephen Tweedie
 *	(sct@redhat.com), 1993, 1998
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 *	(jj@sunsite.ms.mff.cuni.cz)
 *
22
 *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
23
24
25
26
27
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/time.h>
28
#include <linux/jbd2.h>
29
30
31
32
33
34
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
35
#include <linux/pagevec.h>
36
#include <linux/mpage.h>
37
#include <linux/namei.h>
38
39
#include <linux/uio.h>
#include <linux/bio.h>
40

41
#include "ext4_jbd2.h"
42
43
#include "xattr.h"
#include "acl.h"
44
#include "ext4_extents.h"
45

46
47
#include <trace/events/ext4.h>

48
49
#define MPAGE_DA_EXTENT_TAIL 0x01

50
51
52
static inline int ext4_begin_ordered_truncate(struct inode *inode,
					      loff_t new_size)
{
53
54
55
56
	return jbd2_journal_begin_ordered_truncate(
					EXT4_SB(inode->i_sb)->s_journal,
					&EXT4_I(inode)->jinode,
					new_size);
57
58
}

59
60
static void ext4_invalidatepage(struct page *page, unsigned long offset);

61
62
63
/*
 * Test whether an inode is a fast symlink.
 */
64
static int ext4_inode_is_fast_symlink(struct inode *inode)
65
{
66
	int ea_blocks = EXT4_I(inode)->i_file_acl ?
67
68
69
70
71
72
		(inode->i_sb->s_blocksize >> 9) : 0;

	return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
}

/*
73
 * The ext4 forget function must perform a revoke if we are freeing data
74
75
76
77
78
79
 * which has been journaled.  Metadata (eg. indirect blocks) must be
 * revoked in all cases.
 *
 * "bh" may be NULL: a metadata block may have been freed from memory
 * but there may still be a record of it in the journal, and that record
 * still needs to be revoked.
80
 *
81
82
 * If the handle isn't valid we're not journaling, but we still need to
 * call into ext4_journal_revoke() to put the buffer head.
83
 */
84
int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
85
		struct buffer_head *bh, ext4_fsblk_t blocknr)
86
87
88
89
90
91
92
93
{
	int err;

	might_sleep();

	BUFFER_TRACE(bh, "enter");

	jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "
94
		  "data mode %x\n",
95
96
97
98
99
100
101
102
		  bh, is_metadata, inode->i_mode,
		  test_opt(inode->i_sb, DATA_FLAGS));

	/* Never use the revoke function if we are doing full data
	 * journaling: there is no need to, and a V1 superblock won't
	 * support it.  Otherwise, only skip the revoke on un-journaled
	 * data blocks. */

103
104
	if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
	    (!is_metadata && !ext4_should_journal_data(inode))) {
105
		if (bh) {
106
			BUFFER_TRACE(bh, "call jbd2_journal_forget");
107
			return ext4_journal_forget(handle, bh);
108
109
110
111
112
113
114
		}
		return 0;
	}

	/*
	 * data!=journal && (is_metadata || should_journal_data(inode))
	 */
115
116
	BUFFER_TRACE(bh, "call ext4_journal_revoke");
	err = ext4_journal_revoke(handle, blocknr, bh);
117
	if (err)
118
		ext4_abort(inode->i_sb, __func__,
119
120
121
122
123
124
125
126
127
128
129
			   "error %d when attempting revoke", err);
	BUFFER_TRACE(bh, "exit");
	return err;
}

/*
 * Work out how many blocks we need to proceed with the next chunk of a
 * truncate transaction.
 */
static unsigned long blocks_for_truncate(struct inode *inode)
{
Aneesh Kumar K.V's avatar
Aneesh Kumar K.V committed
130
	ext4_lblk_t needed;
131
132
133
134
135
136

	needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);

	/* Give ourselves just enough room to cope with inodes in which
	 * i_blocks is corrupt: we've seen disk corruptions in the past
	 * which resulted in random data in an inode which looked enough
137
	 * like a regular file for ext4 to try to delete it.  Things
138
139
140
141
142
143
144
	 * will go a bit crazy if that happens, but at least we should
	 * try not to panic the whole kernel. */
	if (needed < 2)
		needed = 2;

	/* But we need to bound the transaction so we don't overflow the
	 * journal. */
145
146
	if (needed > EXT4_MAX_TRANS_DATA)
		needed = EXT4_MAX_TRANS_DATA;
147

148
	return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
}

/*
 * Truncate transactions can be complex and absolutely huge.  So we need to
 * be able to restart the transaction at a conventient checkpoint to make
 * sure we don't overflow the journal.
 *
 * start_transaction gets us a new handle for a truncate transaction,
 * and extend_transaction tries to extend the existing one a bit.  If
 * extend fails, we need to propagate the failure up and restart the
 * transaction in the top-level truncate loop. --sct
 */
static handle_t *start_transaction(struct inode *inode)
{
	handle_t *result;

165
	result = ext4_journal_start(inode, blocks_for_truncate(inode));
166
167
168
	if (!IS_ERR(result))
		return result;

169
	ext4_std_error(inode->i_sb, PTR_ERR(result));
170
171
172
173
174
175
176
177
178
179
180
	return result;
}

/*
 * Try to extend this transaction for the purposes of truncation.
 *
 * Returns 0 if we managed to create more room.  If we can't create more
 * room, and the transaction must be restarted we return 1.
 */
static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
{
181
182
183
	if (!ext4_handle_valid(handle))
		return 0;
	if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
184
		return 0;
185
	if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
186
187
188
189
190
191
192
193
194
		return 0;
	return 1;
}

/*
 * Restart the transaction associated with *handle.  This does a commit,
 * so before we call here everything must be consistently dirtied against
 * this transaction.
 */
195
196
 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
				 int nblocks)
197
{
198
199
200
201
202
203
204
205
	int ret;

	/*
	 * Drop i_data_sem to avoid deadlock with ext4_get_blocks At this
	 * moment, get_block can be called only for blocks inside i_size since
	 * page cache has been already dropped and writes are blocked by
	 * i_mutex. So we can safely drop the i_data_sem here.
	 */
206
	BUG_ON(EXT4_JOURNAL(inode) == NULL);
207
	jbd_debug(2, "restarting handle %p\n", handle);
208
209
210
211
212
	up_write(&EXT4_I(inode)->i_data_sem);
	ret = ext4_journal_restart(handle, blocks_for_truncate(inode));
	down_write(&EXT4_I(inode)->i_data_sem);

	return ret;
213
214
215
216
217
}

/*
 * Called at the last iput() if i_nlink is zero.
 */
218
void ext4_delete_inode(struct inode *inode)
219
220
{
	handle_t *handle;
221
	int err;
222

223
224
	if (ext4_should_order_data(inode))
		ext4_begin_ordered_truncate(inode, 0);
225
226
227
228
229
	truncate_inode_pages(&inode->i_data, 0);

	if (is_bad_inode(inode))
		goto no_delete;

230
	handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
231
	if (IS_ERR(handle)) {
232
		ext4_std_error(inode->i_sb, PTR_ERR(handle));
233
234
235
236
237
		/*
		 * If we're going to skip the normal cleanup, we still need to
		 * make sure that the in-core orphan linked list is properly
		 * cleaned up.
		 */
238
		ext4_orphan_del(NULL, inode);
239
240
241
242
		goto no_delete;
	}

	if (IS_SYNC(inode))
243
		ext4_handle_sync(handle);
244
	inode->i_size = 0;
245
246
247
248
249
250
	err = ext4_mark_inode_dirty(handle, inode);
	if (err) {
		ext4_warning(inode->i_sb, __func__,
			     "couldn't mark inode dirty (err %d)", err);
		goto stop_handle;
	}
251
	if (inode->i_blocks)
252
		ext4_truncate(inode);
253
254
255
256
257
258
259

	/*
	 * ext4_ext_truncate() doesn't reserve any slop when it
	 * restarts journal transactions; therefore there may not be
	 * enough credits left in the handle to remove the inode from
	 * the orphan list and set the dtime field.
	 */
260
	if (!ext4_handle_has_enough_credits(handle, 3)) {
261
262
263
264
265
266
267
268
269
270
271
272
		err = ext4_journal_extend(handle, 3);
		if (err > 0)
			err = ext4_journal_restart(handle, 3);
		if (err != 0) {
			ext4_warning(inode->i_sb, __func__,
				     "couldn't extend journal (err %d)", err);
		stop_handle:
			ext4_journal_stop(handle);
			goto no_delete;
		}
	}

273
	/*
274
	 * Kill off the orphan record which ext4_truncate created.
275
	 * AKPM: I think this can be inside the above `if'.
276
	 * Note that ext4_orphan_del() has to be able to cope with the
277
	 * deletion of a non-existent orphan - this is because we don't
278
	 * know if ext4_truncate() actually created an orphan record.
279
280
	 * (Well, we could do this if we need to, but heck - it works)
	 */
281
282
	ext4_orphan_del(handle, inode);
	EXT4_I(inode)->i_dtime	= get_seconds();
283
284
285
286
287
288
289
290

	/*
	 * One subtle ordering requirement: if anything has gone wrong
	 * (transaction abort, IO errors, whatever), then we can still
	 * do these next steps (the fs will already have been marked as
	 * having errors), but we can't free the inode if the mark_dirty
	 * fails.
	 */
291
	if (ext4_mark_inode_dirty(handle, inode))
292
293
294
		/* If that failed, just do the required in-core inode clear. */
		clear_inode(inode);
	else
295
296
		ext4_free_inode(handle, inode);
	ext4_journal_stop(handle);
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
	return;
no_delete:
	clear_inode(inode);	/* We must guarantee clearing of inode... */
}

typedef struct {
	__le32	*p;
	__le32	key;
	struct buffer_head *bh;
} Indirect;

static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
{
	p->key = *(p->p = v);
	p->bh = bh;
}

/**
315
 *	ext4_block_to_path - parse the block number into array of offsets
316
317
318
 *	@inode: inode in question (we are only interested in its superblock)
 *	@i_block: block number to be parsed
 *	@offsets: array to store the offsets in
Dave Kleikamp's avatar
Dave Kleikamp committed
319
320
 *	@boundary: set this non-zero if the referred-to block is likely to be
 *	       followed (on disk) by an indirect block.
321
 *
322
 *	To store the locations of file's data ext4 uses a data structure common
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
 *	for UNIX filesystems - tree of pointers anchored in the inode, with
 *	data blocks at leaves and indirect blocks in intermediate nodes.
 *	This function translates the block number into path in that tree -
 *	return value is the path length and @offsets[n] is the offset of
 *	pointer to (n+1)th node in the nth one. If @block is out of range
 *	(negative or too large) warning is printed and zero returned.
 *
 *	Note: function doesn't find node addresses, so no IO is needed. All
 *	we need to know is the capacity of indirect blocks (taken from the
 *	inode->i_sb).
 */

/*
 * Portability note: the last comparison (check that we fit into triple
 * indirect block) is spelled differently, because otherwise on an
 * architecture with 32-bit longs and 8Kb pages we might get into trouble
 * if our filesystem had 8Kb blocks. We might use long long, but that would
 * kill us on x86. Oh, well, at least the sign propagation does not matter -
 * i_block would have to be negative in the very beginning, so we would not
 * get there at all.
 */

345
static int ext4_block_to_path(struct inode *inode,
346
347
			      ext4_lblk_t i_block,
			      ext4_lblk_t offsets[4], int *boundary)
348
{
349
350
351
	int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
	int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
	const long direct_blocks = EXT4_NDIR_BLOCKS,
352
353
354
355
356
		indirect_blocks = ptrs,
		double_blocks = (1 << (ptrs_bits * 2));
	int n = 0;
	int final = 0;

357
	if (i_block < direct_blocks) {
358
359
		offsets[n++] = i_block;
		final = direct_blocks;
360
	} else if ((i_block -= direct_blocks) < indirect_blocks) {
361
		offsets[n++] = EXT4_IND_BLOCK;
362
363
364
		offsets[n++] = i_block;
		final = ptrs;
	} else if ((i_block -= indirect_blocks) < double_blocks) {
365
		offsets[n++] = EXT4_DIND_BLOCK;
366
367
368
369
		offsets[n++] = i_block >> ptrs_bits;
		offsets[n++] = i_block & (ptrs - 1);
		final = ptrs;
	} else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
370
		offsets[n++] = EXT4_TIND_BLOCK;
371
372
373
374
375
		offsets[n++] = i_block >> (ptrs_bits * 2);
		offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
		offsets[n++] = i_block & (ptrs - 1);
		final = ptrs;
	} else {
376
		ext4_warning(inode->i_sb, "ext4_block_to_path",
377
378
379
			     "block %lu > max in inode %lu",
			     i_block + direct_blocks +
			     indirect_blocks + double_blocks, inode->i_ino);
380
381
382
383
384
385
	}
	if (boundary)
		*boundary = final - 1 - (i_block & (ptrs - 1));
	return n;
}

386
static int __ext4_check_blockref(const char *function, struct inode *inode,
387
388
				 __le32 *p, unsigned int max)
{
389
	__le32 *bref = p;
390
391
	unsigned int blk;

392
	while (bref < p+max) {
393
		blk = le32_to_cpu(*bref++);
394
395
		if (blk &&
		    unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
396
						    blk, 1))) {
397
			ext4_error(inode->i_sb, function,
398
399
				   "invalid block reference %u "
				   "in inode #%lu", blk, inode->i_ino);
400
401
402
403
			return -EIO;
		}
	}
	return 0;
404
405
406
407
}


#define ext4_check_indirect_blockref(inode, bh)                         \
408
	__ext4_check_blockref(__func__, inode, (__le32 *)(bh)->b_data,  \
409
410
411
			      EXT4_ADDR_PER_BLOCK((inode)->i_sb))

#define ext4_check_inode_blockref(inode)                                \
412
	__ext4_check_blockref(__func__, inode, EXT4_I(inode)->i_data,   \
413
414
			      EXT4_NDIR_BLOCKS)

415
/**
416
 *	ext4_get_branch - read the chain of indirect blocks leading to data
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
 *	@inode: inode in question
 *	@depth: depth of the chain (1 - direct pointer, etc.)
 *	@offsets: offsets of pointers in inode/indirect blocks
 *	@chain: place to store the result
 *	@err: here we store the error value
 *
 *	Function fills the array of triples <key, p, bh> and returns %NULL
 *	if everything went OK or the pointer to the last filled triple
 *	(incomplete one) otherwise. Upon the return chain[i].key contains
 *	the number of (i+1)-th block in the chain (as it is stored in memory,
 *	i.e. little-endian 32-bit), chain[i].p contains the address of that
 *	number (it points into struct inode for i==0 and into the bh->b_data
 *	for i>0) and chain[i].bh points to the buffer_head of i-th indirect
 *	block for i>0 and NULL for i==0. In other words, it holds the block
 *	numbers of the chain, addresses they were taken from (and where we can
 *	verify that chain did not change) and buffer_heads hosting these
 *	numbers.
 *
 *	Function stops when it stumbles upon zero pointer (absent block)
 *		(pointer to last triple returned, *@err == 0)
 *	or when it gets an IO error reading an indirect block
 *		(ditto, *@err == -EIO)
 *	or when it reads all @depth-1 indirect blocks successfully and finds
 *	the whole chain, all way to the data (returns %NULL, *err == 0).
441
442
 *
 *      Need to be called with
443
 *      down_read(&EXT4_I(inode)->i_data_sem)
444
 */
Aneesh Kumar K.V's avatar
Aneesh Kumar K.V committed
445
446
static Indirect *ext4_get_branch(struct inode *inode, int depth,
				 ext4_lblk_t  *offsets,
447
448
449
450
451
452
453
454
				 Indirect chain[4], int *err)
{
	struct super_block *sb = inode->i_sb;
	Indirect *p = chain;
	struct buffer_head *bh;

	*err = 0;
	/* i_data is not going away, no lock needed */
455
	add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
456
457
458
	if (!p->key)
		goto no_block;
	while (--depth) {
459
460
		bh = sb_getblk(sb, le32_to_cpu(p->key));
		if (unlikely(!bh))
461
			goto failure;
462

463
464
465
466
467
468
469
470
471
472
473
		if (!bh_uptodate_or_lock(bh)) {
			if (bh_submit_read(bh) < 0) {
				put_bh(bh);
				goto failure;
			}
			/* validate block references */
			if (ext4_check_indirect_blockref(inode, bh)) {
				put_bh(bh);
				goto failure;
			}
		}
474

475
		add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
476
477
478
479
480
481
482
483
484
485
486
487
488
		/* Reader: end */
		if (!p->key)
			goto no_block;
	}
	return NULL;

failure:
	*err = -EIO;
no_block:
	return p;
}

/**
489
 *	ext4_find_near - find a place for allocation with sufficient locality
490
491
492
 *	@inode: owner
 *	@ind: descriptor of indirect block.
 *
493
 *	This function returns the preferred place for block allocation.
494
495
496
497
498
499
500
501
502
503
504
505
506
507
 *	It is used when heuristic for sequential allocation fails.
 *	Rules are:
 *	  + if there is a block to the left of our position - allocate near it.
 *	  + if pointer will live in indirect block - allocate near that block.
 *	  + if pointer will live in inode - allocate in the same
 *	    cylinder group.
 *
 * In the latter case we colour the starting block by the callers PID to
 * prevent it from clashing with concurrent allocations for a different inode
 * in the same block group.   The PID is used here so that functionally related
 * files will be close-by on-disk.
 *
 *	Caller must make sure that @ind is valid and will stay that way.
 */
508
static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
509
{
510
	struct ext4_inode_info *ei = EXT4_I(inode);
511
	__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
512
	__le32 *p;
513
	ext4_fsblk_t bg_start;
514
	ext4_fsblk_t last_block;
515
	ext4_grpblk_t colour;
516
517
	ext4_group_t block_group;
	int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532

	/* Try to find previous block */
	for (p = ind->p - 1; p >= start; p--) {
		if (*p)
			return le32_to_cpu(*p);
	}

	/* No such thing, so let's try location of indirect block */
	if (ind->bh)
		return ind->bh->b_blocknr;

	/*
	 * It is going to be referred to from the inode itself? OK, just put it
	 * into the same cylinder group then.
	 */
533
534
535
536
537
538
539
	block_group = ei->i_block_group;
	if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
		block_group &= ~(flex_size-1);
		if (S_ISREG(inode->i_mode))
			block_group++;
	}
	bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
540
541
	last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;

542
543
544
545
546
547
548
	/*
	 * If we are doing delayed allocation, we don't need take
	 * colour into account.
	 */
	if (test_opt(inode->i_sb, DELALLOC))
		return bg_start;

549
550
	if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
		colour = (current->pid % 16) *
551
			(EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
552
553
	else
		colour = (current->pid % 16) * ((last_block - bg_start) / 16);
554
555
556
557
	return bg_start + colour;
}

/**
558
 *	ext4_find_goal - find a preferred place for allocation.
559
560
561
562
 *	@inode: owner
 *	@block:  block we want
 *	@partial: pointer to the last triple within a chain
 *
563
 *	Normally this function find the preferred place for block allocation,
564
 *	returns it.
565
566
 *	Because this is only used for non-extent files, we limit the block nr
 *	to 32 bits.
567
 */
Aneesh Kumar K.V's avatar
Aneesh Kumar K.V committed
568
static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
569
				   Indirect *partial)
570
{
571
572
	ext4_fsblk_t goal;

573
	/*
574
	 * XXX need to get goal block from mballoc's data structures
575
576
	 */

577
578
579
	goal = ext4_find_near(inode, partial);
	goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
	return goal;
580
581
582
}

/**
583
 *	ext4_blks_to_allocate: Look up the block map and count the number
584
585
586
587
588
589
590
591
592
593
 *	of direct blocks need to be allocated for the given branch.
 *
 *	@branch: chain of indirect blocks
 *	@k: number of blocks need for indirect blocks
 *	@blks: number of data blocks to be mapped.
 *	@blocks_to_boundary:  the offset in the indirect block
 *
 *	return the total number of blocks to be allocate, including the
 *	direct and indirect blocks.
 */
594
static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
595
				 int blocks_to_boundary)
596
{
597
	unsigned int count = 0;
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620

	/*
	 * Simple case, [t,d]Indirect block(s) has not allocated yet
	 * then it's clear blocks on that path have not allocated
	 */
	if (k > 0) {
		/* right now we don't handle cross boundary allocation */
		if (blks < blocks_to_boundary + 1)
			count += blks;
		else
			count += blocks_to_boundary + 1;
		return count;
	}

	count++;
	while (count < blks && count <= blocks_to_boundary &&
		le32_to_cpu(*(branch[0].p + count)) == 0) {
		count++;
	}
	return count;
}

/**
621
 *	ext4_alloc_blocks: multiple allocate blocks needed for a branch
622
623
624
625
626
627
628
629
 *	@indirect_blks: the number of blocks need to allocate for indirect
 *			blocks
 *
 *	@new_blocks: on return it will store the new block numbers for
 *	the indirect blocks(if needed) and the first direct block,
 *	@blks:	on return it will store the total number of allocated
 *		direct blocks
 */
630
static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
631
632
633
			     ext4_lblk_t iblock, ext4_fsblk_t goal,
			     int indirect_blks, int blks,
			     ext4_fsblk_t new_blocks[4], int *err)
634
{
635
	struct ext4_allocation_request ar;
636
	int target, i;
637
	unsigned long count = 0, blk_allocated = 0;
638
	int index = 0;
639
	ext4_fsblk_t current_block = 0;
640
641
642
643
644
645
646
647
648
649
	int ret = 0;

	/*
	 * Here we try to allocate the requested multiple blocks at once,
	 * on a best-effort basis.
	 * To build a branch, we should allocate blocks for
	 * the indirect blocks(if not allocated yet), and at least
	 * the first direct block of this branch.  That's the
	 * minimum number of blocks need to allocate(required)
	 */
650
651
652
	/* first we try to allocate the indirect blocks */
	target = indirect_blks;
	while (target > 0) {
653
654
		count = target;
		/* allocating blocks for indirect blocks and direct blocks */
655
656
		current_block = ext4_new_meta_blocks(handle, inode,
							goal, &count, err);
657
658
659
		if (*err)
			goto failed_out;

660
661
		BUG_ON(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS);

662
663
664
665
666
667
		target -= count;
		/* allocate blocks for indirect blocks */
		while (index < indirect_blks && count) {
			new_blocks[index++] = current_block++;
			count--;
		}
668
669
670
671
672
673
674
675
676
		if (count > 0) {
			/*
			 * save the new block number
			 * for the first direct block
			 */
			new_blocks[index] = current_block;
			printk(KERN_INFO "%s returned more blocks than "
						"requested\n", __func__);
			WARN_ON(1);
677
			break;
678
		}
679
680
	}

681
682
683
684
685
	target = blks - count ;
	blk_allocated = count;
	if (!target)
		goto allocated;
	/* Now allocate data blocks */
686
687
688
689
690
691
692
693
694
695
	memset(&ar, 0, sizeof(ar));
	ar.inode = inode;
	ar.goal = goal;
	ar.len = target;
	ar.logical = iblock;
	if (S_ISREG(inode->i_mode))
		/* enable in-core preallocation only for regular files */
		ar.flags = EXT4_MB_HINT_DATA;

	current_block = ext4_mb_new_blocks(handle, &ar, err);
696
	BUG_ON(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS);
697

698
699
700
701
702
703
704
705
706
	if (*err && (target == blks)) {
		/*
		 * if the allocation failed and we didn't allocate
		 * any blocks before
		 */
		goto failed_out;
	}
	if (!*err) {
		if (target == blks) {
707
708
709
710
			/*
			 * save the new block number
			 * for the first direct block
			 */
711
712
			new_blocks[index] = current_block;
		}
713
		blk_allocated += ar.len;
714
715
	}
allocated:
716
	/* total number of blocks allocated for direct blocks */
717
	ret = blk_allocated;
718
719
720
	*err = 0;
	return ret;
failed_out:
721
	for (i = 0; i < index; i++)
722
		ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
723
724
725
726
	return ret;
}

/**
727
 *	ext4_alloc_branch - allocate and set up a chain of blocks.
728
729
730
731
732
733
734
735
736
737
 *	@inode: owner
 *	@indirect_blks: number of allocated indirect blocks
 *	@blks: number of allocated direct blocks
 *	@offsets: offsets (in the blocks) to store the pointers to next.
 *	@branch: place to store the chain in.
 *
 *	This function allocates blocks, zeroes out all but the last one,
 *	links them into chain and (if we are synchronous) writes them to disk.
 *	In other words, it prepares a branch that can be spliced onto the
 *	inode. It stores the information about that chain in the branch[], in
738
 *	the same format as ext4_get_branch() would do. We are calling it after
739
740
 *	we had read the existing part of chain and partial points to the last
 *	triple of that (one with zero ->key). Upon the exit we have the same
741
 *	picture as after the successful ext4_get_block(), except that in one
742
743
744
745
746
747
 *	place chain is disconnected - *branch->p is still zero (we did not
 *	set the last link), but branch->key contains the number that should
 *	be placed into *branch->p to fill that gap.
 *
 *	If allocation fails we free all blocks we've allocated (and forget
 *	their buffer_heads) and return the error value the from failed
748
 *	ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
749
750
 *	as described above and return 0.
 */
751
static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
752
753
754
			     ext4_lblk_t iblock, int indirect_blks,
			     int *blks, ext4_fsblk_t goal,
			     ext4_lblk_t *offsets, Indirect *branch)
755
756
757
758
759
760
{
	int blocksize = inode->i_sb->s_blocksize;
	int i, n = 0;
	int err = 0;
	struct buffer_head *bh;
	int num;
761
762
	ext4_fsblk_t new_blocks[4];
	ext4_fsblk_t current_block;
763

764
	num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
				*blks, new_blocks, &err);
	if (err)
		return err;

	branch[0].key = cpu_to_le32(new_blocks[0]);
	/*
	 * metadata blocks and data blocks are allocated.
	 */
	for (n = 1; n <= indirect_blks;  n++) {
		/*
		 * Get buffer_head for parent block, zero it out
		 * and set the pointer to new one, then send
		 * parent to disk.
		 */
		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
		branch[n].bh = bh;
		lock_buffer(bh);
		BUFFER_TRACE(bh, "call get_create_access");
783
		err = ext4_journal_get_create_access(handle, bh);
784
		if (err) {
785
786
			/* Don't brelse(bh) here; it's done in
			 * ext4_journal_forget() below */
787
788
789
790
791
792
793
794
			unlock_buffer(bh);
			goto failed;
		}

		memset(bh->b_data, 0, blocksize);
		branch[n].p = (__le32 *) bh->b_data + offsets[n];
		branch[n].key = cpu_to_le32(new_blocks[n]);
		*branch[n].p = branch[n].key;
795
		if (n == indirect_blks) {
796
797
798
799
800
801
			current_block = new_blocks[n];
			/*
			 * End of chain, update the last new metablock of
			 * the chain to point to the new allocated
			 * data blocks numbers
			 */
802
			for (i = 1; i < num; i++)
803
804
805
806
807
808
				*(branch[n].p + i) = cpu_to_le32(++current_block);
		}
		BUFFER_TRACE(bh, "marking uptodate");
		set_buffer_uptodate(bh);
		unlock_buffer(bh);

809
810
		BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
		err = ext4_handle_dirty_metadata(handle, inode, bh);
811
812
813
814
815
816
817
818
		if (err)
			goto failed;
	}
	*blks = num;
	return err;
failed:
	/* Allocation failed, free what we already allocated */
	for (i = 1; i <= n ; i++) {
819
		BUFFER_TRACE(branch[i].bh, "call jbd2_journal_forget");
820
		ext4_journal_forget(handle, branch[i].bh);
821
	}
822
	for (i = 0; i < indirect_blks; i++)
823
		ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
824

825
	ext4_free_blocks(handle, inode, new_blocks[i], num, 0);
826
827
828
829
830

	return err;
}

/**
831
 * ext4_splice_branch - splice the allocated branch onto inode.
832
833
834
 * @inode: owner
 * @block: (logical) number of block we are adding
 * @chain: chain of indirect blocks (with a missing link - see
835
 *	ext4_alloc_branch)
836
837
838
839
840
841
842
843
 * @where: location of missing link
 * @num:   number of indirect blocks we are adding
 * @blks:  number of direct blocks we are adding
 *
 * This function fills the missing link and does all housekeeping needed in
 * inode (->i_blocks, etc.). In case of success we end up with the full
 * chain to new block and return 0.
 */
844
static int ext4_splice_branch(handle_t *handle, struct inode *inode,
845
846
			      ext4_lblk_t block, Indirect *where, int num,
			      int blks)
847
848
849
{
	int i;
	int err = 0;
850
	ext4_fsblk_t current_block;
851
852
853
854
855
856
857
858

	/*
	 * If we're splicing into a [td]indirect block (as opposed to the
	 * inode) then we need to get write access to the [td]indirect block
	 * before the splice.
	 */
	if (where->bh) {
		BUFFER_TRACE(where->bh, "get_write_access");
859
		err = ext4_journal_get_write_access(handle, where->bh);
860
861
862
863
864
865
866
867
868
869
870
871
872
873
		if (err)
			goto err_out;
	}
	/* That's it */

	*where->p = where->key;

	/*
	 * Update the host buffer_head or inode to point to more just allocated
	 * direct blocks blocks
	 */
	if (num == 0 && blks > 1) {
		current_block = le32_to_cpu(where->key) + 1;
		for (i = 1; i < blks; i++)
874
			*(where->p + i) = cpu_to_le32(current_block++);
875
876
877
878
879
880
881
882
883
884
885
	}

	/* We are done with atomic stuff, now do the rest of housekeeping */
	/* had we spliced it onto indirect block? */
	if (where->bh) {
		/*
		 * If we spliced it onto an indirect block, we haven't
		 * altered the inode.  Note however that if it is being spliced
		 * onto an indirect block at the very end of the file (the
		 * file is growing) then we *will* alter the inode to reflect
		 * the new i_size.  But that is not done here - it is done in
886
		 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
887
888
		 */
		jbd_debug(5, "splicing indirect only\n");
889
890
		BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
		err = ext4_handle_dirty_metadata(handle, inode, where->bh);
891
892
893
894
895
896
		if (err)
			goto err_out;
	} else {
		/*
		 * OK, we spliced it into the inode itself on a direct block.
		 */
897
		ext4_mark_inode_dirty(handle, inode);
898
899
900
901
902
903
		jbd_debug(5, "splicing direct\n");
	}
	return err;

err_out:
	for (i = 1; i <= num; i++) {
904
		BUFFER_TRACE(where[i].bh, "call jbd2_journal_forget");
905
		ext4_journal_forget(handle, where[i].bh);
906
907
		ext4_free_blocks(handle, inode,
					le32_to_cpu(where[i-1].key), 1, 0);
908
	}
909
	ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks, 0);
910
911
912
913
914

	return err;
}

/*
915
916
917
918
 * The ext4_ind_get_blocks() function handles non-extents inodes
 * (i.e., using the traditional indirect/double-indirect i_blocks
 * scheme) for ext4_get_blocks().
 *
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
 * Allocation strategy is simple: if we have to allocate something, we will
 * have to go the whole way to leaf. So let's do it before attaching anything
 * to tree, set linkage between the newborn blocks, write them if sync is
 * required, recheck the path, free and repeat if check fails, otherwise
 * set the last missing link (that will protect us from any truncate-generated
 * removals - all blocks on the path are immune now) and possibly force the
 * write on the parent block.
 * That has a nice additional property: no special recovery from the failed
 * allocations is needed - we simply release blocks and do not touch anything
 * reachable from inode.
 *
 * `handle' can be NULL if create == 0.
 *
 * return > 0, # of blocks mapped or allocated.
 * return = 0, if plain lookup failed.
 * return < 0, error case.
935
 *
936
937
938
939
940
 * The ext4_ind_get_blocks() function should be called with
 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
 * blocks.
941
 */
942
static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
943
944
945
			       ext4_lblk_t iblock, unsigned int maxblocks,
			       struct buffer_head *bh_result,
			       int flags)
946
947
{
	int err = -EIO;
Aneesh Kumar K.V's avatar
Aneesh Kumar K.V committed
948
	ext4_lblk_t offsets[4];
949
950
	Indirect chain[4];
	Indirect *partial;
951
	ext4_fsblk_t goal;
952
953
954
955
	int indirect_blks;
	int blocks_to_boundary = 0;
	int depth;
	int count = 0;
956
	ext4_fsblk_t first_block = 0;
957

958
	J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
959
	J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
Aneesh Kumar K.V's avatar
Aneesh Kumar K.V committed
960
	depth = ext4_block_to_path(inode, iblock, offsets,
961
				   &blocks_to_boundary);
962
963
964
965

	if (depth == 0)
		goto out;

966
	partial = ext4_get_branch(inode, depth, offsets, chain, &err);
967
968
969
970
971
972
973
974

	/* Simplest case - block found, no allocation needed */
	if (!partial) {
		first_block = le32_to_cpu(chain[depth - 1].key);
		clear_buffer_new(bh_result);
		count++;
		/*map more blocks*/
		while (count < maxblocks && count <= blocks_to_boundary) {
975
			ext4_fsblk_t blk;
976
977
978
979
980
981
982
983

			blk = le32_to_cpu(*(chain[depth-1].p + count));

			if (blk == first_block + count)
				count++;
			else
				break;
		}
984
		goto got_it;
985
986
987
	}

	/* Next simple case - plain lookup or failed read of indirect block */
988
	if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
989
990
991
		goto cleanup;

	/*
992
	 * Okay, we need to do block allocation.
993
	*/
994
	goal = ext4_find_goal(inode, iblock, partial);
995
996
997
998
999
1000

	/* the number of blocks need to allocate for [d,t]indirect blocks */
	indirect_blks = (chain + depth) - partial - 1;

	/*
	 * Next look up the indirect map to count the totoal number of
For faster browsing, not all history is shown. View entire blame