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1 /*
2  *  linux/fs/ext4/balloc.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  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10  *  Big-endian to little-endian byte-swapping/bitmaps by
11  *        David S. Miller (davem@caip.rutgers.edu), 1995
12  */
13 
14 #include <linux/time.h>
15 #include <linux/capability.h>
16 #include <linux/fs.h>
17 #include <linux/jbd2.h>
18 #include <linux/quotaops.h>
19 #include <linux/buffer_head.h>
20 #include "ext4.h"
21 #include "ext4_jbd2.h"
22 #include "group.h"
23 #include "mballoc.h"
24 
25 /*
26  * balloc.c contains the blocks allocation and deallocation routines
27  */
28 
29 /*
30  * Calculate the block group number and offset, given a block number
31  */
ext4_get_group_no_and_offset(struct super_block * sb,ext4_fsblk_t blocknr,ext4_group_t * blockgrpp,ext4_grpblk_t * offsetp)32 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
33 		ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
34 {
35 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
36 	ext4_grpblk_t offset;
37 
38 	blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
39 	offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
40 	if (offsetp)
41 		*offsetp = offset;
42 	if (blockgrpp)
43 		*blockgrpp = blocknr;
44 
45 }
46 
ext4_block_in_group(struct super_block * sb,ext4_fsblk_t block,ext4_group_t block_group)47 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
48 			ext4_group_t block_group)
49 {
50 	ext4_group_t actual_group;
51 	ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
52 	if (actual_group == block_group)
53 		return 1;
54 	return 0;
55 }
56 
ext4_group_used_meta_blocks(struct super_block * sb,ext4_group_t block_group)57 static int ext4_group_used_meta_blocks(struct super_block *sb,
58 				ext4_group_t block_group)
59 {
60 	ext4_fsblk_t tmp;
61 	struct ext4_sb_info *sbi = EXT4_SB(sb);
62 	/* block bitmap, inode bitmap, and inode table blocks */
63 	int used_blocks = sbi->s_itb_per_group + 2;
64 
65 	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
66 		struct ext4_group_desc *gdp;
67 		struct buffer_head *bh;
68 
69 		gdp = ext4_get_group_desc(sb, block_group, &bh);
70 		if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
71 					block_group))
72 			used_blocks--;
73 
74 		if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
75 					block_group))
76 			used_blocks--;
77 
78 		tmp = ext4_inode_table(sb, gdp);
79 		for (; tmp < ext4_inode_table(sb, gdp) +
80 				sbi->s_itb_per_group; tmp++) {
81 			if (!ext4_block_in_group(sb, tmp, block_group))
82 				used_blocks -= 1;
83 		}
84 	}
85 	return used_blocks;
86 }
87 
88 /* Initializes an uninitialized block bitmap if given, and returns the
89  * number of blocks free in the group. */
ext4_init_block_bitmap(struct super_block * sb,struct buffer_head * bh,ext4_group_t block_group,struct ext4_group_desc * gdp)90 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
91 		 ext4_group_t block_group, struct ext4_group_desc *gdp)
92 {
93 	int bit, bit_max;
94 	unsigned free_blocks, group_blocks;
95 	struct ext4_sb_info *sbi = EXT4_SB(sb);
96 
97 	if (bh) {
98 		J_ASSERT_BH(bh, buffer_locked(bh));
99 
100 		/* If checksum is bad mark all blocks used to prevent allocation
101 		 * essentially implementing a per-group read-only flag. */
102 		if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
103 			ext4_error(sb, __func__,
104 				  "Checksum bad for group %u", block_group);
105 			ext4_free_blks_set(sb, gdp, 0);
106 			ext4_free_inodes_set(sb, gdp, 0);
107 			ext4_itable_unused_set(sb, gdp, 0);
108 			memset(bh->b_data, 0xff, sb->s_blocksize);
109 			return 0;
110 		}
111 		memset(bh->b_data, 0, sb->s_blocksize);
112 	}
113 
114 	/* Check for superblock and gdt backups in this group */
115 	bit_max = ext4_bg_has_super(sb, block_group);
116 
117 	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
118 	    block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
119 			  sbi->s_desc_per_block) {
120 		if (bit_max) {
121 			bit_max += ext4_bg_num_gdb(sb, block_group);
122 			bit_max +=
123 				le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
124 		}
125 	} else { /* For META_BG_BLOCK_GROUPS */
126 		bit_max += ext4_bg_num_gdb(sb, block_group);
127 	}
128 
129 	if (block_group == sbi->s_groups_count - 1) {
130 		/*
131 		 * Even though mke2fs always initialize first and last group
132 		 * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
133 		 * to make sure we calculate the right free blocks
134 		 */
135 		group_blocks = ext4_blocks_count(sbi->s_es) -
136 			le32_to_cpu(sbi->s_es->s_first_data_block) -
137 			(EXT4_BLOCKS_PER_GROUP(sb) * (sbi->s_groups_count - 1));
138 	} else {
139 		group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
140 	}
141 
142 	free_blocks = group_blocks - bit_max;
143 
144 	if (bh) {
145 		ext4_fsblk_t start, tmp;
146 		int flex_bg = 0;
147 
148 		for (bit = 0; bit < bit_max; bit++)
149 			ext4_set_bit(bit, bh->b_data);
150 
151 		start = ext4_group_first_block_no(sb, block_group);
152 
153 		if (EXT4_HAS_INCOMPAT_FEATURE(sb,
154 					      EXT4_FEATURE_INCOMPAT_FLEX_BG))
155 			flex_bg = 1;
156 
157 		/* Set bits for block and inode bitmaps, and inode table */
158 		tmp = ext4_block_bitmap(sb, gdp);
159 		if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
160 			ext4_set_bit(tmp - start, bh->b_data);
161 
162 		tmp = ext4_inode_bitmap(sb, gdp);
163 		if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
164 			ext4_set_bit(tmp - start, bh->b_data);
165 
166 		tmp = ext4_inode_table(sb, gdp);
167 		for (; tmp < ext4_inode_table(sb, gdp) +
168 				sbi->s_itb_per_group; tmp++) {
169 			if (!flex_bg ||
170 				ext4_block_in_group(sb, tmp, block_group))
171 				ext4_set_bit(tmp - start, bh->b_data);
172 		}
173 		/*
174 		 * Also if the number of blocks within the group is
175 		 * less than the blocksize * 8 ( which is the size
176 		 * of bitmap ), set rest of the block bitmap to 1
177 		 */
178 		mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
179 	}
180 	return free_blocks - ext4_group_used_meta_blocks(sb, block_group);
181 }
182 
183 
184 /*
185  * The free blocks are managed by bitmaps.  A file system contains several
186  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
187  * block for inodes, N blocks for the inode table and data blocks.
188  *
189  * The file system contains group descriptors which are located after the
190  * super block.  Each descriptor contains the number of the bitmap block and
191  * the free blocks count in the block.  The descriptors are loaded in memory
192  * when a file system is mounted (see ext4_fill_super).
193  */
194 
195 
196 #define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)
197 
198 /**
199  * ext4_get_group_desc() -- load group descriptor from disk
200  * @sb:			super block
201  * @block_group:	given block group
202  * @bh:			pointer to the buffer head to store the block
203  *			group descriptor
204  */
ext4_get_group_desc(struct super_block * sb,ext4_group_t block_group,struct buffer_head ** bh)205 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
206 					     ext4_group_t block_group,
207 					     struct buffer_head **bh)
208 {
209 	unsigned int group_desc;
210 	unsigned int offset;
211 	struct ext4_group_desc *desc;
212 	struct ext4_sb_info *sbi = EXT4_SB(sb);
213 
214 	if (block_group >= sbi->s_groups_count) {
215 		ext4_error(sb, "ext4_get_group_desc",
216 			   "block_group >= groups_count - "
217 			   "block_group = %u, groups_count = %u",
218 			   block_group, sbi->s_groups_count);
219 
220 		return NULL;
221 	}
222 	smp_rmb();
223 
224 	group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
225 	offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
226 	if (!sbi->s_group_desc[group_desc]) {
227 		ext4_error(sb, "ext4_get_group_desc",
228 			   "Group descriptor not loaded - "
229 			   "block_group = %u, group_desc = %u, desc = %u",
230 			   block_group, group_desc, offset);
231 		return NULL;
232 	}
233 
234 	desc = (struct ext4_group_desc *)(
235 		(__u8 *)sbi->s_group_desc[group_desc]->b_data +
236 		offset * EXT4_DESC_SIZE(sb));
237 	if (bh)
238 		*bh = sbi->s_group_desc[group_desc];
239 	return desc;
240 }
241 
ext4_valid_block_bitmap(struct super_block * sb,struct ext4_group_desc * desc,unsigned int block_group,struct buffer_head * bh)242 static int ext4_valid_block_bitmap(struct super_block *sb,
243 					struct ext4_group_desc *desc,
244 					unsigned int block_group,
245 					struct buffer_head *bh)
246 {
247 	ext4_grpblk_t offset;
248 	ext4_grpblk_t next_zero_bit;
249 	ext4_fsblk_t bitmap_blk;
250 	ext4_fsblk_t group_first_block;
251 
252 	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
253 		/* with FLEX_BG, the inode/block bitmaps and itable
254 		 * blocks may not be in the group at all
255 		 * so the bitmap validation will be skipped for those groups
256 		 * or it has to also read the block group where the bitmaps
257 		 * are located to verify they are set.
258 		 */
259 		return 1;
260 	}
261 	group_first_block = ext4_group_first_block_no(sb, block_group);
262 
263 	/* check whether block bitmap block number is set */
264 	bitmap_blk = ext4_block_bitmap(sb, desc);
265 	offset = bitmap_blk - group_first_block;
266 	if (!ext4_test_bit(offset, bh->b_data))
267 		/* bad block bitmap */
268 		goto err_out;
269 
270 	/* check whether the inode bitmap block number is set */
271 	bitmap_blk = ext4_inode_bitmap(sb, desc);
272 	offset = bitmap_blk - group_first_block;
273 	if (!ext4_test_bit(offset, bh->b_data))
274 		/* bad block bitmap */
275 		goto err_out;
276 
277 	/* check whether the inode table block number is set */
278 	bitmap_blk = ext4_inode_table(sb, desc);
279 	offset = bitmap_blk - group_first_block;
280 	next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
281 				offset + EXT4_SB(sb)->s_itb_per_group,
282 				offset);
283 	if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
284 		/* good bitmap for inode tables */
285 		return 1;
286 
287 err_out:
288 	ext4_error(sb, __func__,
289 			"Invalid block bitmap - "
290 			"block_group = %d, block = %llu",
291 			block_group, bitmap_blk);
292 	return 0;
293 }
294 /**
295  * ext4_read_block_bitmap()
296  * @sb:			super block
297  * @block_group:	given block group
298  *
299  * Read the bitmap for a given block_group,and validate the
300  * bits for block/inode/inode tables are set in the bitmaps
301  *
302  * Return buffer_head on success or NULL in case of failure.
303  */
304 struct buffer_head *
ext4_read_block_bitmap(struct super_block * sb,ext4_group_t block_group)305 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
306 {
307 	struct ext4_group_desc *desc;
308 	struct buffer_head *bh = NULL;
309 	ext4_fsblk_t bitmap_blk;
310 
311 	desc = ext4_get_group_desc(sb, block_group, NULL);
312 	if (!desc)
313 		return NULL;
314 	bitmap_blk = ext4_block_bitmap(sb, desc);
315 	bh = sb_getblk(sb, bitmap_blk);
316 	if (unlikely(!bh)) {
317 		ext4_error(sb, __func__,
318 			    "Cannot read block bitmap - "
319 			    "block_group = %u, block_bitmap = %llu",
320 			    block_group, bitmap_blk);
321 		return NULL;
322 	}
323 
324 	if (bitmap_uptodate(bh))
325 		return bh;
326 
327 	lock_buffer(bh);
328 	if (bitmap_uptodate(bh)) {
329 		unlock_buffer(bh);
330 		return bh;
331 	}
332 	spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
333 	if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
334 		ext4_init_block_bitmap(sb, bh, block_group, desc);
335 		set_bitmap_uptodate(bh);
336 		set_buffer_uptodate(bh);
337 		spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
338 		unlock_buffer(bh);
339 		return bh;
340 	}
341 	spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
342 	if (buffer_uptodate(bh)) {
343 		/*
344 		 * if not uninit if bh is uptodate,
345 		 * bitmap is also uptodate
346 		 */
347 		set_bitmap_uptodate(bh);
348 		unlock_buffer(bh);
349 		return bh;
350 	}
351 	/*
352 	 * submit the buffer_head for read. We can
353 	 * safely mark the bitmap as uptodate now.
354 	 * We do it here so the bitmap uptodate bit
355 	 * get set with buffer lock held.
356 	 */
357 	set_bitmap_uptodate(bh);
358 	if (bh_submit_read(bh) < 0) {
359 		put_bh(bh);
360 		ext4_error(sb, __func__,
361 			    "Cannot read block bitmap - "
362 			    "block_group = %u, block_bitmap = %llu",
363 			    block_group, bitmap_blk);
364 		return NULL;
365 	}
366 	ext4_valid_block_bitmap(sb, desc, block_group, bh);
367 	/*
368 	 * file system mounted not to panic on error,
369 	 * continue with corrupt bitmap
370 	 */
371 	return bh;
372 }
373 
374 /**
375  * ext4_add_groupblocks() -- Add given blocks to an existing group
376  * @handle:			handle to this transaction
377  * @sb:				super block
378  * @block:			start physcial block to add to the block group
379  * @count:			number of blocks to free
380  *
381  * This marks the blocks as free in the bitmap. We ask the
382  * mballoc to reload the buddy after this by setting group
383  * EXT4_GROUP_INFO_NEED_INIT_BIT flag
384  */
ext4_add_groupblocks(handle_t * handle,struct super_block * sb,ext4_fsblk_t block,unsigned long count)385 void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
386 			 ext4_fsblk_t block, unsigned long count)
387 {
388 	struct buffer_head *bitmap_bh = NULL;
389 	struct buffer_head *gd_bh;
390 	ext4_group_t block_group;
391 	ext4_grpblk_t bit;
392 	unsigned int i;
393 	struct ext4_group_desc *desc;
394 	struct ext4_super_block *es;
395 	struct ext4_sb_info *sbi;
396 	int err = 0, ret, blk_free_count;
397 	ext4_grpblk_t blocks_freed;
398 	struct ext4_group_info *grp;
399 
400 	sbi = EXT4_SB(sb);
401 	es = sbi->s_es;
402 	ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
403 
404 	ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
405 	grp = ext4_get_group_info(sb, block_group);
406 	/*
407 	 * Check to see if we are freeing blocks across a group
408 	 * boundary.
409 	 */
410 	if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
411 		goto error_return;
412 	}
413 	bitmap_bh = ext4_read_block_bitmap(sb, block_group);
414 	if (!bitmap_bh)
415 		goto error_return;
416 	desc = ext4_get_group_desc(sb, block_group, &gd_bh);
417 	if (!desc)
418 		goto error_return;
419 
420 	if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
421 	    in_range(ext4_inode_bitmap(sb, desc), block, count) ||
422 	    in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
423 	    in_range(block + count - 1, ext4_inode_table(sb, desc),
424 		     sbi->s_itb_per_group)) {
425 		ext4_error(sb, __func__,
426 			   "Adding blocks in system zones - "
427 			   "Block = %llu, count = %lu",
428 			   block, count);
429 		goto error_return;
430 	}
431 
432 	/*
433 	 * We are about to add blocks to the bitmap,
434 	 * so we need undo access.
435 	 */
436 	BUFFER_TRACE(bitmap_bh, "getting undo access");
437 	err = ext4_journal_get_undo_access(handle, bitmap_bh);
438 	if (err)
439 		goto error_return;
440 
441 	/*
442 	 * We are about to modify some metadata.  Call the journal APIs
443 	 * to unshare ->b_data if a currently-committing transaction is
444 	 * using it
445 	 */
446 	BUFFER_TRACE(gd_bh, "get_write_access");
447 	err = ext4_journal_get_write_access(handle, gd_bh);
448 	if (err)
449 		goto error_return;
450 	/*
451 	 * make sure we don't allow a parallel init on other groups in the
452 	 * same buddy cache
453 	 */
454 	down_write(&grp->alloc_sem);
455 	for (i = 0, blocks_freed = 0; i < count; i++) {
456 		BUFFER_TRACE(bitmap_bh, "clear bit");
457 		if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
458 						bit + i, bitmap_bh->b_data)) {
459 			ext4_error(sb, __func__,
460 				   "bit already cleared for block %llu",
461 				   (ext4_fsblk_t)(block + i));
462 			BUFFER_TRACE(bitmap_bh, "bit already cleared");
463 		} else {
464 			blocks_freed++;
465 		}
466 	}
467 	spin_lock(sb_bgl_lock(sbi, block_group));
468 	blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
469 	ext4_free_blks_set(sb, desc, blk_free_count);
470 	desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
471 	spin_unlock(sb_bgl_lock(sbi, block_group));
472 	percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
473 
474 	if (sbi->s_log_groups_per_flex) {
475 		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
476 		spin_lock(sb_bgl_lock(sbi, flex_group));
477 		sbi->s_flex_groups[flex_group].free_blocks += blocks_freed;
478 		spin_unlock(sb_bgl_lock(sbi, flex_group));
479 	}
480 	/*
481 	 * request to reload the buddy with the
482 	 * new bitmap information
483 	 */
484 	set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
485 	ext4_mb_update_group_info(grp, blocks_freed);
486 	up_write(&grp->alloc_sem);
487 
488 	/* We dirtied the bitmap block */
489 	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
490 	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
491 
492 	/* And the group descriptor block */
493 	BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
494 	ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
495 	if (!err)
496 		err = ret;
497 	sb->s_dirt = 1;
498 
499 error_return:
500 	brelse(bitmap_bh);
501 	ext4_std_error(sb, err);
502 	return;
503 }
504 
505 /**
506  * ext4_free_blocks() -- Free given blocks and update quota
507  * @handle:		handle for this transaction
508  * @inode:		inode
509  * @block:		start physical block to free
510  * @count:		number of blocks to count
511  * @metadata: 		Are these metadata blocks
512  */
ext4_free_blocks(handle_t * handle,struct inode * inode,ext4_fsblk_t block,unsigned long count,int metadata)513 void ext4_free_blocks(handle_t *handle, struct inode *inode,
514 			ext4_fsblk_t block, unsigned long count,
515 			int metadata)
516 {
517 	struct super_block *sb;
518 	unsigned long dquot_freed_blocks;
519 
520 	/* this isn't the right place to decide whether block is metadata
521 	 * inode.c/extents.c knows better, but for safety ... */
522 	if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
523 		metadata = 1;
524 
525 	/* We need to make sure we don't reuse
526 	 * block released untill the transaction commit.
527 	 * writeback mode have weak data consistency so
528 	 * don't force data as metadata when freeing block
529 	 * for writeback mode.
530 	 */
531 	if (metadata == 0 && !ext4_should_writeback_data(inode))
532 		metadata = 1;
533 
534 	sb = inode->i_sb;
535 
536 	ext4_mb_free_blocks(handle, inode, block, count,
537 			    metadata, &dquot_freed_blocks);
538 	if (dquot_freed_blocks)
539 		DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
540 	return;
541 }
542 
543 /**
544  * ext4_has_free_blocks()
545  * @sbi:	in-core super block structure.
546  * @nblocks:	number of needed blocks
547  *
548  * Check if filesystem has nblocks free & available for allocation.
549  * On success return 1, return 0 on failure.
550  */
ext4_has_free_blocks(struct ext4_sb_info * sbi,s64 nblocks)551 int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
552 {
553 	s64 free_blocks, dirty_blocks, root_blocks;
554 	struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
555 	struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
556 
557 	free_blocks  = percpu_counter_read_positive(fbc);
558 	dirty_blocks = percpu_counter_read_positive(dbc);
559 	root_blocks = ext4_r_blocks_count(sbi->s_es);
560 
561 	if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
562 						EXT4_FREEBLOCKS_WATERMARK) {
563 		free_blocks  = percpu_counter_sum_positive(fbc);
564 		dirty_blocks = percpu_counter_sum_positive(dbc);
565 		if (dirty_blocks < 0) {
566 			printk(KERN_CRIT "Dirty block accounting "
567 					"went wrong %lld\n",
568 					(long long)dirty_blocks);
569 		}
570 	}
571 	/* Check whether we have space after
572 	 * accounting for current dirty blocks & root reserved blocks.
573 	 */
574 	if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
575 		return 1;
576 
577 	/* Hm, nope.  Are (enough) root reserved blocks available? */
578 	if (sbi->s_resuid == current_fsuid() ||
579 	    ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
580 	    capable(CAP_SYS_RESOURCE)) {
581 		if (free_blocks >= (nblocks + dirty_blocks))
582 			return 1;
583 	}
584 
585 	return 0;
586 }
587 
ext4_claim_free_blocks(struct ext4_sb_info * sbi,s64 nblocks)588 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
589 						s64 nblocks)
590 {
591 	if (ext4_has_free_blocks(sbi, nblocks)) {
592 		percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
593 		return 0;
594 	} else
595 		return -ENOSPC;
596 }
597 
598 /**
599  * ext4_should_retry_alloc()
600  * @sb:			super block
601  * @retries		number of attemps has been made
602  *
603  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
604  * it is profitable to retry the operation, this function will wait
605  * for the current or commiting transaction to complete, and then
606  * return TRUE.
607  *
608  * if the total number of retries exceed three times, return FALSE.
609  */
ext4_should_retry_alloc(struct super_block * sb,int * retries)610 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
611 {
612 	if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
613 	    (*retries)++ > 3 ||
614 	    !EXT4_SB(sb)->s_journal)
615 		return 0;
616 
617 	jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
618 
619 	return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
620 }
621 
622 /*
623  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
624  *
625  * @handle:             handle to this transaction
626  * @inode:              file inode
627  * @goal:               given target block(filesystem wide)
628  * @count:		pointer to total number of blocks needed
629  * @errp:               error code
630  *
631  * Return 1st allocated block number on success, *count stores total account
632  * error stores in errp pointer
633  */
ext4_new_meta_blocks(handle_t * handle,struct inode * inode,ext4_fsblk_t goal,unsigned long * count,int * errp)634 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
635 		ext4_fsblk_t goal, unsigned long *count, int *errp)
636 {
637 	struct ext4_allocation_request ar;
638 	ext4_fsblk_t ret;
639 
640 	memset(&ar, 0, sizeof(ar));
641 	/* Fill with neighbour allocated blocks */
642 	ar.inode = inode;
643 	ar.goal = goal;
644 	ar.len = count ? *count : 1;
645 
646 	ret = ext4_mb_new_blocks(handle, &ar, errp);
647 	if (count)
648 		*count = ar.len;
649 
650 	/*
651 	 * Account for the allocated meta blocks
652 	 */
653 	if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
654 		spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
655 		EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
656 		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
657 	}
658 	return ret;
659 }
660 
661 /**
662  * ext4_count_free_blocks() -- count filesystem free blocks
663  * @sb:		superblock
664  *
665  * Adds up the number of free blocks from each block group.
666  */
ext4_count_free_blocks(struct super_block * sb)667 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
668 {
669 	ext4_fsblk_t desc_count;
670 	struct ext4_group_desc *gdp;
671 	ext4_group_t i;
672 	ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
673 #ifdef EXT4FS_DEBUG
674 	struct ext4_super_block *es;
675 	ext4_fsblk_t bitmap_count;
676 	unsigned int x;
677 	struct buffer_head *bitmap_bh = NULL;
678 
679 	es = EXT4_SB(sb)->s_es;
680 	desc_count = 0;
681 	bitmap_count = 0;
682 	gdp = NULL;
683 
684 	smp_rmb();
685 	for (i = 0; i < ngroups; i++) {
686 		gdp = ext4_get_group_desc(sb, i, NULL);
687 		if (!gdp)
688 			continue;
689 		desc_count += ext4_free_blks_count(sb, gdp);
690 		brelse(bitmap_bh);
691 		bitmap_bh = ext4_read_block_bitmap(sb, i);
692 		if (bitmap_bh == NULL)
693 			continue;
694 
695 		x = ext4_count_free(bitmap_bh, sb->s_blocksize);
696 		printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
697 			i, ext4_free_blks_count(sb, gdp), x);
698 		bitmap_count += x;
699 	}
700 	brelse(bitmap_bh);
701 	printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
702 		", computed = %llu, %llu\n", ext4_free_blocks_count(es),
703 	       desc_count, bitmap_count);
704 	return bitmap_count;
705 #else
706 	desc_count = 0;
707 	smp_rmb();
708 	for (i = 0; i < ngroups; i++) {
709 		gdp = ext4_get_group_desc(sb, i, NULL);
710 		if (!gdp)
711 			continue;
712 		desc_count += ext4_free_blks_count(sb, gdp);
713 	}
714 
715 	return desc_count;
716 #endif
717 }
718 
test_root(ext4_group_t a,int b)719 static inline int test_root(ext4_group_t a, int b)
720 {
721 	int num = b;
722 
723 	while (a > num)
724 		num *= b;
725 	return num == a;
726 }
727 
ext4_group_sparse(ext4_group_t group)728 static int ext4_group_sparse(ext4_group_t group)
729 {
730 	if (group <= 1)
731 		return 1;
732 	if (!(group & 1))
733 		return 0;
734 	return (test_root(group, 7) || test_root(group, 5) ||
735 		test_root(group, 3));
736 }
737 
738 /**
739  *	ext4_bg_has_super - number of blocks used by the superblock in group
740  *	@sb: superblock for filesystem
741  *	@group: group number to check
742  *
743  *	Return the number of blocks used by the superblock (primary or backup)
744  *	in this group.  Currently this will be only 0 or 1.
745  */
ext4_bg_has_super(struct super_block * sb,ext4_group_t group)746 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
747 {
748 	if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
749 				EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
750 			!ext4_group_sparse(group))
751 		return 0;
752 	return 1;
753 }
754 
ext4_bg_num_gdb_meta(struct super_block * sb,ext4_group_t group)755 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
756 					ext4_group_t group)
757 {
758 	unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
759 	ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
760 	ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
761 
762 	if (group == first || group == first + 1 || group == last)
763 		return 1;
764 	return 0;
765 }
766 
ext4_bg_num_gdb_nometa(struct super_block * sb,ext4_group_t group)767 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
768 					ext4_group_t group)
769 {
770 	return ext4_bg_has_super(sb, group) ? EXT4_SB(sb)->s_gdb_count : 0;
771 }
772 
773 /**
774  *	ext4_bg_num_gdb - number of blocks used by the group table in group
775  *	@sb: superblock for filesystem
776  *	@group: group number to check
777  *
778  *	Return the number of blocks used by the group descriptor table
779  *	(primary or backup) in this group.  In the future there may be a
780  *	different number of descriptor blocks in each group.
781  */
ext4_bg_num_gdb(struct super_block * sb,ext4_group_t group)782 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
783 {
784 	unsigned long first_meta_bg =
785 			le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
786 	unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
787 
788 	if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
789 			metagroup < first_meta_bg)
790 		return ext4_bg_num_gdb_nometa(sb, group);
791 
792 	return ext4_bg_num_gdb_meta(sb,group);
793 
794 }
795 
796