1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/ext2/balloc.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 *
10 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
11 * Big-endian to little-endian byte-swapping/bitmaps by
12 * David S. Miller (davem@caip.rutgers.edu), 1995
13 */
14
15 #include "ext2.h"
16 #include <linux/quotaops.h>
17 #include <linux/slab.h>
18 #include <linux/sched.h>
19 #include <linux/cred.h>
20 #include <linux/buffer_head.h>
21 #include <linux/capability.h>
22
23 /*
24 * balloc.c contains the blocks allocation and deallocation routines
25 */
26
27 /*
28 * The free blocks are managed by bitmaps. A file system contains several
29 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
30 * block for inodes, N blocks for the inode table and data blocks.
31 *
32 * The file system contains group descriptors which are located after the
33 * super block. Each descriptor contains the number of the bitmap block and
34 * the free blocks count in the block. The descriptors are loaded in memory
35 * when a file system is mounted (see ext2_fill_super).
36 */
37
38
39 struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
40 unsigned int block_group,
41 struct buffer_head ** bh)
42 {
43 unsigned long group_desc;
44 unsigned long offset;
45 struct ext2_group_desc * desc;
46 struct ext2_sb_info *sbi = EXT2_SB(sb);
47
48 if (block_group >= sbi->s_groups_count) {
49 WARN(1, "block_group >= groups_count - "
50 "block_group = %d, groups_count = %lu",
51 block_group, sbi->s_groups_count);
52
53 return NULL;
54 }
55
56 group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
57 offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
58 if (!sbi->s_group_desc[group_desc]) {
59 WARN(1, "Group descriptor not loaded - "
60 "block_group = %d, group_desc = %lu, desc = %lu",
61 block_group, group_desc, offset);
62 return NULL;
63 }
64
65 desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;
66 if (bh)
67 *bh = sbi->s_group_desc[group_desc];
68 return desc + offset;
69 }
70
71 static int ext2_valid_block_bitmap(struct super_block *sb,
72 struct ext2_group_desc *desc,
73 unsigned int block_group,
74 struct buffer_head *bh)
75 {
76 ext2_grpblk_t offset;
77 ext2_grpblk_t next_zero_bit;
78 ext2_fsblk_t bitmap_blk;
79 ext2_fsblk_t group_first_block;
80 ext2_grpblk_t max_bit;
81
82 group_first_block = ext2_group_first_block_no(sb, block_group);
83 max_bit = ext2_group_last_block_no(sb, block_group) - group_first_block;
84
85 /* check whether block bitmap block number is set */
86 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
87 offset = bitmap_blk - group_first_block;
88 if (offset < 0 || offset > max_bit ||
89 !ext2_test_bit(offset, bh->b_data))
90 /* bad block bitmap */
91 goto err_out;
92
93 /* check whether the inode bitmap block number is set */
94 bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
95 offset = bitmap_blk - group_first_block;
96 if (offset < 0 || offset > max_bit ||
97 !ext2_test_bit(offset, bh->b_data))
98 /* bad block bitmap */
99 goto err_out;
100
101 /* check whether the inode table block number is set */
102 bitmap_blk = le32_to_cpu(desc->bg_inode_table);
103 offset = bitmap_blk - group_first_block;
104 if (offset < 0 || offset > max_bit ||
105 offset + EXT2_SB(sb)->s_itb_per_group - 1 > max_bit)
106 goto err_out;
107 next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
108 offset + EXT2_SB(sb)->s_itb_per_group,
109 offset);
110 if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
111 /* good bitmap for inode tables */
112 return 1;
113
114 err_out:
115 ext2_error(sb, __func__,
116 "Invalid block bitmap - "
117 "block_group = %d, block = %lu",
118 block_group, bitmap_blk);
119 return 0;
120 }
121
122 /*
123 * Read the bitmap for a given block_group,and validate the
124 * bits for block/inode/inode tables are set in the bitmaps
125 *
126 * Return buffer_head on success or NULL in case of failure.
127 */
128 static struct buffer_head *
129 read_block_bitmap(struct super_block *sb, unsigned int block_group)
130 {
131 struct ext2_group_desc * desc;
132 struct buffer_head * bh = NULL;
133 ext2_fsblk_t bitmap_blk;
134 int ret;
135
136 desc = ext2_get_group_desc(sb, block_group, NULL);
137 if (!desc)
138 return NULL;
139 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
140 bh = sb_getblk(sb, bitmap_blk);
141 if (unlikely(!bh)) {
142 ext2_error(sb, __func__,
143 "Cannot read block bitmap - "
144 "block_group = %d, block_bitmap = %u",
145 block_group, le32_to_cpu(desc->bg_block_bitmap));
146 return NULL;
147 }
148 ret = bh_read(bh, 0);
149 if (ret > 0)
150 return bh;
151 if (ret < 0) {
152 brelse(bh);
153 ext2_error(sb, __func__,
154 "Cannot read block bitmap - "
155 "block_group = %d, block_bitmap = %u",
156 block_group, le32_to_cpu(desc->bg_block_bitmap));
157 return NULL;
158 }
159
160 ext2_valid_block_bitmap(sb, desc, block_group, bh);
161 /*
162 * file system mounted not to panic on error, continue with corrupt
163 * bitmap
164 */
165 return bh;
166 }
167
168 static void group_adjust_blocks(struct super_block *sb, int group_no,
169 struct ext2_group_desc *desc, struct buffer_head *bh, int count)
170 {
171 if (count) {
172 struct ext2_sb_info *sbi = EXT2_SB(sb);
173 unsigned free_blocks;
174
175 spin_lock(sb_bgl_lock(sbi, group_no));
176 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
177 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
178 spin_unlock(sb_bgl_lock(sbi, group_no));
179 mark_buffer_dirty(bh);
180 }
181 }
182
183 /*
184 * The reservation window structure operations
185 * --------------------------------------------
186 * Operations include:
187 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
188 *
189 * We use a red-black tree to represent per-filesystem reservation
190 * windows.
191 *
192 */
193
194 /**
195 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
196 * @root: root of per-filesystem reservation rb tree
197 * @verbose: verbose mode
198 * @fn: function which wishes to dump the reservation map
199 *
200 * If verbose is turned on, it will print the whole block reservation
201 * windows(start, end). Otherwise, it will only print out the "bad" windows,
202 * those windows that overlap with their immediate neighbors.
203 */
204 #if 1
205 static void __rsv_window_dump(struct rb_root *root, int verbose,
206 const char *fn)
207 {
208 struct rb_node *n;
209 struct ext2_reserve_window_node *rsv, *prev;
210 int bad;
211
212 restart:
213 n = rb_first(root);
214 bad = 0;
215 prev = NULL;
216
217 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
218 while (n) {
219 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
220 if (verbose)
221 printk("reservation window 0x%p "
222 "start: %lu, end: %lu\n",
223 rsv, rsv->rsv_start, rsv->rsv_end);
224 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
225 printk("Bad reservation %p (start >= end)\n",
226 rsv);
227 bad = 1;
228 }
229 if (prev && prev->rsv_end >= rsv->rsv_start) {
230 printk("Bad reservation %p (prev->end >= start)\n",
231 rsv);
232 bad = 1;
233 }
234 if (bad) {
235 if (!verbose) {
236 printk("Restarting reservation walk in verbose mode\n");
237 verbose = 1;
238 goto restart;
239 }
240 }
241 n = rb_next(n);
242 prev = rsv;
243 }
244 printk("Window map complete.\n");
245 BUG_ON(bad);
246 }
247 #define rsv_window_dump(root, verbose) \
248 __rsv_window_dump((root), (verbose), __func__)
249 #else
250 #define rsv_window_dump(root, verbose) do {} while (0)
251 #endif
252
253 /**
254 * goal_in_my_reservation()
255 * @rsv: inode's reservation window
256 * @grp_goal: given goal block relative to the allocation block group
257 * @group: the current allocation block group
258 * @sb: filesystem super block
259 *
260 * Test if the given goal block (group relative) is within the file's
261 * own block reservation window range.
262 *
263 * If the reservation window is outside the goal allocation group, return 0;
264 * grp_goal (given goal block) could be -1, which means no specific
265 * goal block. In this case, always return 1.
266 * If the goal block is within the reservation window, return 1;
267 * otherwise, return 0;
268 */
269 static int
270 goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
271 unsigned int group, struct super_block * sb)
272 {
273 ext2_fsblk_t group_first_block, group_last_block;
274
275 group_first_block = ext2_group_first_block_no(sb, group);
276 group_last_block = ext2_group_last_block_no(sb, group);
277
278 if ((rsv->_rsv_start > group_last_block) ||
279 (rsv->_rsv_end < group_first_block))
280 return 0;
281 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
282 || (grp_goal + group_first_block > rsv->_rsv_end)))
283 return 0;
284 return 1;
285 }
286
287 /**
288 * search_reserve_window()
289 * @root: root of reservation tree
290 * @goal: target allocation block
291 *
292 * Find the reserved window which includes the goal, or the previous one
293 * if the goal is not in any window.
294 * Returns NULL if there are no windows or if all windows start after the goal.
295 */
296 static struct ext2_reserve_window_node *
297 search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
298 {
299 struct rb_node *n = root->rb_node;
300 struct ext2_reserve_window_node *rsv;
301
302 if (!n)
303 return NULL;
304
305 do {
306 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
307
308 if (goal < rsv->rsv_start)
309 n = n->rb_left;
310 else if (goal > rsv->rsv_end)
311 n = n->rb_right;
312 else
313 return rsv;
314 } while (n);
315 /*
316 * We've fallen off the end of the tree: the goal wasn't inside
317 * any particular node. OK, the previous node must be to one
318 * side of the interval containing the goal. If it's the RHS,
319 * we need to back up one.
320 */
321 if (rsv->rsv_start > goal) {
322 n = rb_prev(&rsv->rsv_node);
323 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
324 }
325 return rsv;
326 }
327
328 /*
329 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
330 * @sb: super block
331 * @rsv: reservation window to add
332 *
333 * Must be called with rsv_lock held.
334 */
335 void ext2_rsv_window_add(struct super_block *sb,
336 struct ext2_reserve_window_node *rsv)
337 {
338 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
339 struct rb_node *node = &rsv->rsv_node;
340 ext2_fsblk_t start = rsv->rsv_start;
341
342 struct rb_node ** p = &root->rb_node;
343 struct rb_node * parent = NULL;
344 struct ext2_reserve_window_node *this;
345
346 while (*p)
347 {
348 parent = *p;
349 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
350
351 if (start < this->rsv_start)
352 p = &(*p)->rb_left;
353 else if (start > this->rsv_end)
354 p = &(*p)->rb_right;
355 else {
356 rsv_window_dump(root, 1);
357 BUG();
358 }
359 }
360
361 rb_link_node(node, parent, p);
362 rb_insert_color(node, root);
363 }
364
365 /**
366 * rsv_window_remove() -- unlink a window from the reservation rb tree
367 * @sb: super block
368 * @rsv: reservation window to remove
369 *
370 * Mark the block reservation window as not allocated, and unlink it
371 * from the filesystem reservation window rb tree. Must be called with
372 * rsv_lock held.
373 */
374 static void rsv_window_remove(struct super_block *sb,
375 struct ext2_reserve_window_node *rsv)
376 {
377 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
378 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
379 rsv->rsv_alloc_hit = 0;
380 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
381 }
382
383 /*
384 * rsv_is_empty() -- Check if the reservation window is allocated.
385 * @rsv: given reservation window to check
386 *
387 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
388 */
389 static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
390 {
391 /* a valid reservation end block could not be 0 */
392 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
393 }
394
395 /**
396 * ext2_init_block_alloc_info()
397 * @inode: file inode structure
398 *
399 * Allocate and initialize the reservation window structure, and
400 * link the window to the ext2 inode structure at last
401 *
402 * The reservation window structure is only dynamically allocated
403 * and linked to ext2 inode the first time the open file
404 * needs a new block. So, before every ext2_new_block(s) call, for
405 * regular files, we should check whether the reservation window
406 * structure exists or not. In the latter case, this function is called.
407 * Fail to do so will result in block reservation being turned off for that
408 * open file.
409 *
410 * This function is called from ext2_get_blocks_handle(), also called
411 * when setting the reservation window size through ioctl before the file
412 * is open for write (needs block allocation).
413 *
414 * Needs truncate_mutex protection prior to calling this function.
415 */
416 void ext2_init_block_alloc_info(struct inode *inode)
417 {
418 struct ext2_inode_info *ei = EXT2_I(inode);
419 struct ext2_block_alloc_info *block_i;
420 struct super_block *sb = inode->i_sb;
421
422 block_i = kmalloc(sizeof(*block_i), GFP_KERNEL);
423 if (block_i) {
424 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
425
426 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
427 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
428
429 /*
430 * if filesystem is mounted with NORESERVATION, the goal
431 * reservation window size is set to zero to indicate
432 * block reservation is off
433 */
434 if (!test_opt(sb, RESERVATION))
435 rsv->rsv_goal_size = 0;
436 else
437 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
438 rsv->rsv_alloc_hit = 0;
439 block_i->last_alloc_logical_block = 0;
440 block_i->last_alloc_physical_block = 0;
441 }
442 ei->i_block_alloc_info = block_i;
443 }
444
445 /**
446 * ext2_discard_reservation()
447 * @inode: inode
448 *
449 * Discard(free) block reservation window on last file close, or truncate
450 * or at last iput().
451 *
452 * It is being called in three cases:
453 * ext2_release_file(): last writer closes the file
454 * ext2_clear_inode(): last iput(), when nobody links to this file.
455 * ext2_truncate(): when the block indirect map is about to change.
456 */
457 void ext2_discard_reservation(struct inode *inode)
458 {
459 struct ext2_inode_info *ei = EXT2_I(inode);
460 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
461 struct ext2_reserve_window_node *rsv;
462 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
463
464 if (!block_i)
465 return;
466
467 rsv = &block_i->rsv_window_node;
468 if (!rsv_is_empty(&rsv->rsv_window)) {
469 spin_lock(rsv_lock);
470 if (!rsv_is_empty(&rsv->rsv_window))
471 rsv_window_remove(inode->i_sb, rsv);
472 spin_unlock(rsv_lock);
473 }
474 }
475
476 /**
477 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks
478 * @inode: inode
479 * @block: start physical block to free
480 * @count: number of blocks to free
481 */
482 void ext2_free_blocks(struct inode * inode, ext2_fsblk_t block,
483 unsigned long count)
484 {
485 struct buffer_head *bitmap_bh = NULL;
486 struct buffer_head * bh2;
487 unsigned long block_group;
488 unsigned long bit;
489 unsigned long i;
490 unsigned long overflow;
491 struct super_block * sb = inode->i_sb;
492 struct ext2_sb_info * sbi = EXT2_SB(sb);
493 struct ext2_group_desc * desc;
494 struct ext2_super_block * es = sbi->s_es;
495 unsigned freed = 0, group_freed;
496
497 if (!ext2_data_block_valid(sbi, block, count)) {
498 ext2_error (sb, "ext2_free_blocks",
499 "Freeing blocks not in datazone - "
500 "block = %lu, count = %lu", block, count);
501 goto error_return;
502 }
503
504 ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
505
506 do_more:
507 overflow = 0;
508 block_group = (block - le32_to_cpu(es->s_first_data_block)) /
509 EXT2_BLOCKS_PER_GROUP(sb);
510 bit = (block - le32_to_cpu(es->s_first_data_block)) %
511 EXT2_BLOCKS_PER_GROUP(sb);
512 /*
513 * Check to see if we are freeing blocks across a group
514 * boundary.
515 */
516 if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
517 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
518 count -= overflow;
519 }
520 brelse(bitmap_bh);
521 bitmap_bh = read_block_bitmap(sb, block_group);
522 if (!bitmap_bh)
523 goto error_return;
524
525 desc = ext2_get_group_desc (sb, block_group, &bh2);
526 if (!desc)
527 goto error_return;
528
529 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
530 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
531 in_range (block, le32_to_cpu(desc->bg_inode_table),
532 sbi->s_itb_per_group) ||
533 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
534 sbi->s_itb_per_group)) {
535 ext2_error (sb, "ext2_free_blocks",
536 "Freeing blocks in system zones - "
537 "Block = %lu, count = %lu",
538 block, count);
539 goto error_return;
540 }
541
542 for (i = 0, group_freed = 0; i < count; i++) {
543 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
544 bit + i, bitmap_bh->b_data)) {
545 ext2_error(sb, __func__,
546 "bit already cleared for block %lu", block + i);
547 } else {
548 group_freed++;
549 }
550 }
551
552 mark_buffer_dirty(bitmap_bh);
553 if (sb->s_flags & SB_SYNCHRONOUS)
554 sync_dirty_buffer(bitmap_bh);
555
556 group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
557 freed += group_freed;
558
559 if (overflow) {
560 block += count;
561 count = overflow;
562 goto do_more;
563 }
564 error_return:
565 brelse(bitmap_bh);
566 if (freed) {
567 percpu_counter_add(&sbi->s_freeblocks_counter, freed);
568 dquot_free_block_nodirty(inode, freed);
569 mark_inode_dirty(inode);
570 }
571 }
572
573 /**
574 * bitmap_search_next_usable_block()
575 * @start: the starting block (group relative) of the search
576 * @bh: bufferhead contains the block group bitmap
577 * @maxblocks: the ending block (group relative) of the reservation
578 *
579 * The bitmap search --- search forward through the actual bitmap on disk until
580 * we find a bit free.
581 */
582 static ext2_grpblk_t
583 bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
584 ext2_grpblk_t maxblocks)
585 {
586 ext2_grpblk_t next;
587
588 next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
589 if (next >= maxblocks)
590 return -1;
591 return next;
592 }
593
594 /**
595 * find_next_usable_block()
596 * @start: the starting block (group relative) to find next
597 * allocatable block in bitmap.
598 * @bh: bufferhead contains the block group bitmap
599 * @maxblocks: the ending block (group relative) for the search
600 *
601 * Find an allocatable block in a bitmap. We perform the "most
602 * appropriate allocation" algorithm of looking for a free block near
603 * the initial goal; then for a free byte somewhere in the bitmap;
604 * then for any free bit in the bitmap.
605 */
606 static ext2_grpblk_t
607 find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
608 {
609 ext2_grpblk_t here, next;
610 char *p, *r;
611
612 if (start > 0) {
613 /*
614 * The goal was occupied; search forward for a free
615 * block within the next XX blocks.
616 *
617 * end_goal is more or less random, but it has to be
618 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
619 * next 64-bit boundary is simple..
620 */
621 ext2_grpblk_t end_goal = (start + 63) & ~63;
622 if (end_goal > maxblocks)
623 end_goal = maxblocks;
624 here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
625 if (here < end_goal)
626 return here;
627 ext2_debug("Bit not found near goal\n");
628 }
629
630 here = start;
631 if (here < 0)
632 here = 0;
633
634 p = ((char *)bh->b_data) + (here >> 3);
635 r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
636 next = (r - ((char *)bh->b_data)) << 3;
637
638 if (next < maxblocks && next >= here)
639 return next;
640
641 here = bitmap_search_next_usable_block(here, bh, maxblocks);
642 return here;
643 }
644
645 /**
646 * ext2_try_to_allocate()
647 * @sb: superblock
648 * @group: given allocation block group
649 * @bitmap_bh: bufferhead holds the block bitmap
650 * @grp_goal: given target block within the group
651 * @count: target number of blocks to allocate
652 * @my_rsv: reservation window
653 *
654 * Attempt to allocate blocks within a give range. Set the range of allocation
655 * first, then find the first free bit(s) from the bitmap (within the range),
656 * and at last, allocate the blocks by claiming the found free bit as allocated.
657 *
658 * To set the range of this allocation:
659 * if there is a reservation window, only try to allocate block(s)
660 * from the file's own reservation window;
661 * Otherwise, the allocation range starts from the give goal block,
662 * ends at the block group's last block.
663 *
664 * If we failed to allocate the desired block then we may end up crossing to a
665 * new bitmap.
666 */
667 static int
668 ext2_try_to_allocate(struct super_block *sb, int group,
669 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
670 unsigned long *count,
671 struct ext2_reserve_window *my_rsv)
672 {
673 ext2_fsblk_t group_first_block = ext2_group_first_block_no(sb, group);
674 ext2_fsblk_t group_last_block = ext2_group_last_block_no(sb, group);
675 ext2_grpblk_t start, end;
676 unsigned long num = 0;
677
678 start = 0;
679 end = group_last_block - group_first_block + 1;
680 /* we do allocation within the reservation window if we have a window */
681 if (my_rsv) {
682 if (my_rsv->_rsv_start >= group_first_block)
683 start = my_rsv->_rsv_start - group_first_block;
684 if (my_rsv->_rsv_end < group_last_block)
685 end = my_rsv->_rsv_end - group_first_block + 1;
686 if (grp_goal < start || grp_goal >= end)
687 grp_goal = -1;
688 }
689 BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
690
691 if (grp_goal < 0) {
692 grp_goal = find_next_usable_block(start, bitmap_bh, end);
693 if (grp_goal < 0)
694 goto fail_access;
695 if (!my_rsv) {
696 int i;
697
698 for (i = 0; i < 7 && grp_goal > start &&
699 !ext2_test_bit(grp_goal - 1,
700 bitmap_bh->b_data);
701 i++, grp_goal--)
702 ;
703 }
704 }
705
706 for (; num < *count && grp_goal < end; grp_goal++) {
707 if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
708 grp_goal, bitmap_bh->b_data)) {
709 if (num == 0)
710 continue;
711 break;
712 }
713 num++;
714 }
715
716 if (num == 0)
717 goto fail_access;
718
719 *count = num;
720 return grp_goal - num;
721 fail_access:
722 return -1;
723 }
724
725 /**
726 * find_next_reservable_window - Find a reservable space within the given range.
727 * @search_head: The list to search.
728 * @my_rsv: The reservation we're currently using.
729 * @sb: The super block.
730 * @start_block: The first block we consider to start the real search from
731 * @last_block: The maximum block number that our goal reservable space
732 * could start from.
733 *
734 * It does not allocate the reservation window: alloc_new_reservation()
735 * will do the work later.
736 *
737 * We search the given range, rather than the whole reservation double
738 * linked list, (start_block, last_block) to find a free region that is
739 * of my size and has not been reserved.
740 *
741 * @search_head is not necessarily the list head of the whole filesystem.
742 * We have both head and @start_block to assist the search for the
743 * reservable space. The list starts from head, but we will shift to
744 * the place where start_block is, then start from there, when looking
745 * for a reservable space.
746 *
747 * @last_block is normally the last block in this group. The search will end
748 * when we found the start of next possible reservable space is out
749 * of this boundary. This could handle the cross boundary reservation
750 * window request.
751 *
752 * Return: -1 if we could not find a range of sufficient size. If we could,
753 * return 0 and fill in @my_rsv with the range information.
754 */
755 static int find_next_reservable_window(
756 struct ext2_reserve_window_node *search_head,
757 struct ext2_reserve_window_node *my_rsv,
758 struct super_block * sb,
759 ext2_fsblk_t start_block,
760 ext2_fsblk_t last_block)
761 {
762 struct rb_node *next;
763 struct ext2_reserve_window_node *rsv, *prev;
764 ext2_fsblk_t cur;
765 int size = my_rsv->rsv_goal_size;
766
767 /* TODO: make the start of the reservation window byte-aligned */
768 /* cur = *start_block & ~7;*/
769 cur = start_block;
770 rsv = search_head;
771 if (!rsv)
772 return -1;
773
774 while (1) {
775 if (cur <= rsv->rsv_end)
776 cur = rsv->rsv_end + 1;
777
778 /* TODO?
779 * in the case we could not find a reservable space
780 * that is what is expected, during the re-search, we could
781 * remember what's the largest reservable space we could have
782 * and return that one.
783 *
784 * For now it will fail if we could not find the reservable
785 * space with expected-size (or more)...
786 */
787 if (cur > last_block)
788 return -1; /* fail */
789
790 prev = rsv;
791 next = rb_next(&rsv->rsv_node);
792 rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
793
794 /*
795 * Reached the last reservation, we can just append to the
796 * previous one.
797 */
798 if (!next)
799 break;
800
801 if (cur + size <= rsv->rsv_start) {
802 /*
803 * Found a reserveable space big enough. We could
804 * have a reservation across the group boundary here
805 */
806 break;
807 }
808 }
809 /*
810 * we come here either :
811 * when we reach the end of the whole list,
812 * and there is empty reservable space after last entry in the list.
813 * append it to the end of the list.
814 *
815 * or we found one reservable space in the middle of the list,
816 * return the reservation window that we could append to.
817 * succeed.
818 */
819
820 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
821 rsv_window_remove(sb, my_rsv);
822
823 /*
824 * Let's book the whole available window for now. We will check the
825 * disk bitmap later and then, if there are free blocks then we adjust
826 * the window size if it's larger than requested.
827 * Otherwise, we will remove this node from the tree next time
828 * call find_next_reservable_window.
829 */
830 my_rsv->rsv_start = cur;
831 my_rsv->rsv_end = cur + size - 1;
832 my_rsv->rsv_alloc_hit = 0;
833
834 if (prev != my_rsv)
835 ext2_rsv_window_add(sb, my_rsv);
836
837 return 0;
838 }
839
840 /**
841 * alloc_new_reservation - Allocate a new reservation window.
842 * @my_rsv: The reservation we're currently using.
843 * @grp_goal: The goal block relative to the start of the group.
844 * @sb: The super block.
845 * @group: The group we are trying to allocate in.
846 * @bitmap_bh: The block group block bitmap.
847 *
848 * To make a new reservation, we search part of the filesystem reservation
849 * list (the list inside the group). We try to allocate a new
850 * reservation window near @grp_goal, or the beginning of the
851 * group, if @grp_goal is negative.
852 *
853 * We first find a reservable space after the goal, then from there,
854 * we check the bitmap for the first free block after it. If there is
855 * no free block until the end of group, then the whole group is full,
856 * we failed. Otherwise, check if the free block is inside the expected
857 * reservable space, if so, we succeed.
858 *
859 * If the first free block is outside the reservable space, then start
860 * from the first free block, we search for next available space, and
861 * go on.
862 *
863 * on succeed, a new reservation will be found and inserted into the
864 * list. It contains at least one free block, and it does not overlap
865 * with other reservation windows.
866 *
867 * Return: 0 on success, -1 if we failed to find a reservation window
868 * in this group
869 */
870 static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
871 ext2_grpblk_t grp_goal, struct super_block *sb,
872 unsigned int group, struct buffer_head *bitmap_bh)
873 {
874 struct ext2_reserve_window_node *search_head;
875 ext2_fsblk_t group_first_block, group_end_block, start_block;
876 ext2_grpblk_t first_free_block;
877 struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
878 unsigned long size;
879 int ret;
880 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
881
882 group_first_block = ext2_group_first_block_no(sb, group);
883 group_end_block = ext2_group_last_block_no(sb, group);
884
885 if (grp_goal < 0)
886 start_block = group_first_block;
887 else
888 start_block = grp_goal + group_first_block;
889
890 size = my_rsv->rsv_goal_size;
891
892 if (!rsv_is_empty(&my_rsv->rsv_window)) {
893 /*
894 * if the old reservation is cross group boundary
895 * and if the goal is inside the old reservation window,
896 * we will come here when we just failed to allocate from
897 * the first part of the window. We still have another part
898 * that belongs to the next group. In this case, there is no
899 * point to discard our window and try to allocate a new one
900 * in this group(which will fail). we should
901 * keep the reservation window, just simply move on.
902 *
903 * Maybe we could shift the start block of the reservation
904 * window to the first block of next group.
905 */
906
907 if ((my_rsv->rsv_start <= group_end_block) &&
908 (my_rsv->rsv_end > group_end_block) &&
909 (start_block >= my_rsv->rsv_start))
910 return -1;
911
912 if ((my_rsv->rsv_alloc_hit >
913 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
914 /*
915 * if the previously allocation hit ratio is
916 * greater than 1/2, then we double the size of
917 * the reservation window the next time,
918 * otherwise we keep the same size window
919 */
920 size = size * 2;
921 if (size > EXT2_MAX_RESERVE_BLOCKS)
922 size = EXT2_MAX_RESERVE_BLOCKS;
923 my_rsv->rsv_goal_size= size;
924 }
925 }
926
927 spin_lock(rsv_lock);
928 /*
929 * shift the search start to the window near the goal block
930 */
931 search_head = search_reserve_window(fs_rsv_root, start_block);
932
933 /*
934 * find_next_reservable_window() simply finds a reservable window
935 * inside the given range(start_block, group_end_block).
936 *
937 * To make sure the reservation window has a free bit inside it, we
938 * need to check the bitmap after we found a reservable window.
939 */
940 retry:
941 ret = find_next_reservable_window(search_head, my_rsv, sb,
942 start_block, group_end_block);
943
944 if (ret == -1) {
945 if (!rsv_is_empty(&my_rsv->rsv_window))
946 rsv_window_remove(sb, my_rsv);
947 spin_unlock(rsv_lock);
948 return -1;
949 }
950
951 /*
952 * On success, find_next_reservable_window() returns the
953 * reservation window where there is a reservable space after it.
954 * Before we reserve this reservable space, we need
955 * to make sure there is at least a free block inside this region.
956 *
957 * Search the first free bit on the block bitmap. Search starts from
958 * the start block of the reservable space we just found.
959 */
960 spin_unlock(rsv_lock);
961 first_free_block = bitmap_search_next_usable_block(
962 my_rsv->rsv_start - group_first_block,
963 bitmap_bh, group_end_block - group_first_block + 1);
964
965 if (first_free_block < 0) {
966 /*
967 * no free block left on the bitmap, no point
968 * to reserve the space. return failed.
969 */
970 spin_lock(rsv_lock);
971 if (!rsv_is_empty(&my_rsv->rsv_window))
972 rsv_window_remove(sb, my_rsv);
973 spin_unlock(rsv_lock);
974 return -1; /* failed */
975 }
976
977 start_block = first_free_block + group_first_block;
978 /*
979 * check if the first free block is within the
980 * free space we just reserved
981 */
982 if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
983 return 0; /* success */
984 /*
985 * if the first free bit we found is out of the reservable space
986 * continue search for next reservable space,
987 * start from where the free block is,
988 * we also shift the list head to where we stopped last time
989 */
990 search_head = my_rsv;
991 spin_lock(rsv_lock);
992 goto retry;
993 }
994
995 /**
996 * try_to_extend_reservation()
997 * @my_rsv: given reservation window
998 * @sb: super block
999 * @size: the delta to extend
1000 *
1001 * Attempt to expand the reservation window large enough to have
1002 * required number of free blocks
1003 *
1004 * Since ext2_try_to_allocate() will always allocate blocks within
1005 * the reservation window range, if the window size is too small,
1006 * multiple blocks allocation has to stop at the end of the reservation
1007 * window. To make this more efficient, given the total number of
1008 * blocks needed and the current size of the window, we try to
1009 * expand the reservation window size if necessary on a best-effort
1010 * basis before ext2_new_blocks() tries to allocate blocks.
1011 */
1012 static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1013 struct super_block *sb, int size)
1014 {
1015 struct ext2_reserve_window_node *next_rsv;
1016 struct rb_node *next;
1017 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1018
1019 if (!spin_trylock(rsv_lock))
1020 return;
1021
1022 next = rb_next(&my_rsv->rsv_node);
1023
1024 if (!next)
1025 my_rsv->rsv_end += size;
1026 else {
1027 next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1028
1029 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1030 my_rsv->rsv_end += size;
1031 else
1032 my_rsv->rsv_end = next_rsv->rsv_start - 1;
1033 }
1034 spin_unlock(rsv_lock);
1035 }
1036
1037 /**
1038 * ext2_try_to_allocate_with_rsv()
1039 * @sb: superblock
1040 * @group: given allocation block group
1041 * @bitmap_bh: bufferhead holds the block bitmap
1042 * @grp_goal: given target block within the group
1043 * @count: target number of blocks to allocate
1044 * @my_rsv: reservation window
1045 *
1046 * This is the main function used to allocate a new block and its reservation
1047 * window.
1048 *
1049 * Each time when a new block allocation is need, first try to allocate from
1050 * its own reservation. If it does not have a reservation window, instead of
1051 * looking for a free bit on bitmap first, then look up the reservation list to
1052 * see if it is inside somebody else's reservation window, we try to allocate a
1053 * reservation window for it starting from the goal first. Then do the block
1054 * allocation within the reservation window.
1055 *
1056 * This will avoid keeping on searching the reservation list again and
1057 * again when somebody is looking for a free block (without
1058 * reservation), and there are lots of free blocks, but they are all
1059 * being reserved.
1060 *
1061 * We use a red-black tree for the per-filesystem reservation list.
1062 */
1063 static ext2_grpblk_t
1064 ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1065 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1066 struct ext2_reserve_window_node * my_rsv,
1067 unsigned long *count)
1068 {
1069 ext2_fsblk_t group_first_block, group_last_block;
1070 ext2_grpblk_t ret = 0;
1071 unsigned long num = *count;
1072
1073 /*
1074 * we don't deal with reservation when
1075 * filesystem is mounted without reservation
1076 * or the file is not a regular file
1077 * or last attempt to allocate a block with reservation turned on failed
1078 */
1079 if (my_rsv == NULL) {
1080 return ext2_try_to_allocate(sb, group, bitmap_bh,
1081 grp_goal, count, NULL);
1082 }
1083 /*
1084 * grp_goal is a group relative block number (if there is a goal)
1085 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1086 * first block is a filesystem wide block number
1087 * first block is the block number of the first block in this group
1088 */
1089 group_first_block = ext2_group_first_block_no(sb, group);
1090 group_last_block = ext2_group_last_block_no(sb, group);
1091
1092 /*
1093 * Basically we will allocate a new block from inode's reservation
1094 * window.
1095 *
1096 * We need to allocate a new reservation window, if:
1097 * a) inode does not have a reservation window; or
1098 * b) last attempt to allocate a block from existing reservation
1099 * failed; or
1100 * c) we come here with a goal and with a reservation window
1101 *
1102 * We do not need to allocate a new reservation window if we come here
1103 * at the beginning with a goal and the goal is inside the window, or
1104 * we don't have a goal but already have a reservation window.
1105 * then we could go to allocate from the reservation window directly.
1106 */
1107 while (1) {
1108 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1109 !goal_in_my_reservation(&my_rsv->rsv_window,
1110 grp_goal, group, sb)) {
1111 if (my_rsv->rsv_goal_size < *count)
1112 my_rsv->rsv_goal_size = *count;
1113 ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1114 group, bitmap_bh);
1115 if (ret < 0)
1116 break; /* failed */
1117
1118 if (!goal_in_my_reservation(&my_rsv->rsv_window,
1119 grp_goal, group, sb))
1120 grp_goal = -1;
1121 } else if (grp_goal >= 0) {
1122 int curr = my_rsv->rsv_end -
1123 (grp_goal + group_first_block) + 1;
1124
1125 if (curr < *count)
1126 try_to_extend_reservation(my_rsv, sb,
1127 *count - curr);
1128 }
1129
1130 if ((my_rsv->rsv_start > group_last_block) ||
1131 (my_rsv->rsv_end < group_first_block)) {
1132 ext2_error(sb, __func__,
1133 "Reservation out of group %u range goal %d fsb[%lu,%lu] rsv[%lu, %lu]",
1134 group, grp_goal, group_first_block,
1135 group_last_block, my_rsv->rsv_start,
1136 my_rsv->rsv_end);
1137 rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1138 return -1;
1139 }
1140 ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1141 &num, &my_rsv->rsv_window);
1142 if (ret >= 0) {
1143 my_rsv->rsv_alloc_hit += num;
1144 *count = num;
1145 break; /* succeed */
1146 }
1147 num = *count;
1148 }
1149 return ret;
1150 }
1151
1152 /**
1153 * ext2_has_free_blocks()
1154 * @sbi: in-core super block structure.
1155 *
1156 * Check if filesystem has at least 1 free block available for allocation.
1157 */
1158 static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1159 {
1160 ext2_fsblk_t free_blocks, root_blocks;
1161
1162 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1163 root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1164 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1165 !uid_eq(sbi->s_resuid, current_fsuid()) &&
1166 (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1167 !in_group_p (sbi->s_resgid))) {
1168 return 0;
1169 }
1170 return 1;
1171 }
1172
1173 /*
1174 * Returns 1 if the passed-in block region is valid; 0 if some part overlaps
1175 * with filesystem metadata blocks.
1176 */
1177 int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
1178 unsigned int count)
1179 {
1180 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
1181 (start_blk + count - 1 < start_blk) ||
1182 (start_blk + count - 1 >= le32_to_cpu(sbi->s_es->s_blocks_count)))
1183 return 0;
1184
1185 /* Ensure we do not step over superblock */
1186 if ((start_blk <= sbi->s_sb_block) &&
1187 (start_blk + count - 1 >= sbi->s_sb_block))
1188 return 0;
1189
1190 return 1;
1191 }
1192
1193 /*
1194 * ext2_new_blocks() -- core block(s) allocation function
1195 * @inode: file inode
1196 * @goal: given target block(filesystem wide)
1197 * @count: target number of blocks to allocate
1198 * @errp: error code
1199 * @flags: allocate flags
1200 *
1201 * ext2_new_blocks uses a goal block to assist allocation. If the goal is
1202 * free, or there is a free block within 32 blocks of the goal, that block
1203 * is allocated. Otherwise a forward search is made for a free block; within
1204 * each block group the search first looks for an entire free byte in the block
1205 * bitmap, and then for any free bit if that fails.
1206 * This function also updates quota and i_blocks field.
1207 */
1208 ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1209 unsigned long *count, int *errp, unsigned int flags)
1210 {
1211 struct buffer_head *bitmap_bh = NULL;
1212 struct buffer_head *gdp_bh;
1213 int group_no;
1214 int goal_group;
1215 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1216 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1217 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1218 int bgi; /* blockgroup iteration index */
1219 int performed_allocation = 0;
1220 ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1221 struct super_block *sb;
1222 struct ext2_group_desc *gdp;
1223 struct ext2_super_block *es;
1224 struct ext2_sb_info *sbi;
1225 struct ext2_reserve_window_node *my_rsv = NULL;
1226 struct ext2_block_alloc_info *block_i;
1227 unsigned short windowsz = 0;
1228 unsigned long ngroups;
1229 unsigned long num = *count;
1230 int ret;
1231
1232 *errp = -ENOSPC;
1233 sb = inode->i_sb;
1234
1235 /*
1236 * Check quota for allocation of this block.
1237 */
1238 ret = dquot_alloc_block(inode, num);
1239 if (ret) {
1240 *errp = ret;
1241 return 0;
1242 }
1243
1244 sbi = EXT2_SB(sb);
1245 es = EXT2_SB(sb)->s_es;
1246 ext2_debug("goal=%lu.\n", goal);
1247 /*
1248 * Allocate a block from reservation only when the filesystem is
1249 * mounted with reservation(default,-o reservation), and it's a regular
1250 * file, and the desired window size is greater than 0 (One could use
1251 * ioctl command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn
1252 * off reservation on that particular file). Also do not use the
1253 * reservation window if the caller asked us not to do it.
1254 */
1255 block_i = EXT2_I(inode)->i_block_alloc_info;
1256 if (!(flags & EXT2_ALLOC_NORESERVE) && block_i) {
1257 windowsz = block_i->rsv_window_node.rsv_goal_size;
1258 if (windowsz > 0)
1259 my_rsv = &block_i->rsv_window_node;
1260 }
1261
1262 if (!ext2_has_free_blocks(sbi)) {
1263 *errp = -ENOSPC;
1264 goto out;
1265 }
1266
1267 /*
1268 * First, test whether the goal block is free.
1269 */
1270 if (goal < le32_to_cpu(es->s_first_data_block) ||
1271 goal >= le32_to_cpu(es->s_blocks_count))
1272 goal = le32_to_cpu(es->s_first_data_block);
1273 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1274 EXT2_BLOCKS_PER_GROUP(sb);
1275 goal_group = group_no;
1276 retry_alloc:
1277 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1278 if (!gdp)
1279 goto io_error;
1280
1281 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1282 /*
1283 * if there is not enough free blocks to make a new resevation
1284 * turn off reservation for this allocation
1285 */
1286 if (my_rsv && (free_blocks < windowsz)
1287 && (free_blocks > 0)
1288 && (rsv_is_empty(&my_rsv->rsv_window)))
1289 my_rsv = NULL;
1290
1291 if (free_blocks > 0) {
1292 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1293 EXT2_BLOCKS_PER_GROUP(sb));
1294 /*
1295 * In case we retry allocation (due to fs reservation not
1296 * working out or fs corruption), the bitmap_bh is non-null
1297 * pointer and we have to release it before calling
1298 * read_block_bitmap().
1299 */
1300 brelse(bitmap_bh);
1301 bitmap_bh = read_block_bitmap(sb, group_no);
1302 if (!bitmap_bh)
1303 goto io_error;
1304 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1305 bitmap_bh, grp_target_blk,
1306 my_rsv, &num);
1307 if (grp_alloc_blk >= 0)
1308 goto allocated;
1309 }
1310
1311 ngroups = EXT2_SB(sb)->s_groups_count;
1312 smp_rmb();
1313
1314 /*
1315 * Now search the rest of the groups. We assume that
1316 * group_no and gdp correctly point to the last group visited.
1317 */
1318 for (bgi = 0; bgi < ngroups; bgi++) {
1319 group_no++;
1320 if (group_no >= ngroups)
1321 group_no = 0;
1322 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1323 if (!gdp)
1324 goto io_error;
1325
1326 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1327 /*
1328 * skip this group (and avoid loading bitmap) if there
1329 * are no free blocks
1330 */
1331 if (!free_blocks)
1332 continue;
1333 /*
1334 * skip this group if the number of
1335 * free blocks is less than half of the reservation
1336 * window size.
1337 */
1338 if (my_rsv && (free_blocks <= (windowsz/2)))
1339 continue;
1340
1341 brelse(bitmap_bh);
1342 bitmap_bh = read_block_bitmap(sb, group_no);
1343 if (!bitmap_bh)
1344 goto io_error;
1345 /*
1346 * try to allocate block(s) from this group, without a goal(-1).
1347 */
1348 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1349 bitmap_bh, -1, my_rsv, &num);
1350 if (grp_alloc_blk >= 0)
1351 goto allocated;
1352 }
1353 /*
1354 * We may end up a bogus earlier ENOSPC error due to
1355 * filesystem is "full" of reservations, but
1356 * there maybe indeed free blocks available on disk
1357 * In this case, we just forget about the reservations
1358 * just do block allocation as without reservations.
1359 */
1360 if (my_rsv) {
1361 my_rsv = NULL;
1362 windowsz = 0;
1363 group_no = goal_group;
1364 goto retry_alloc;
1365 }
1366 /* No space left on the device */
1367 *errp = -ENOSPC;
1368 goto out;
1369
1370 allocated:
1371
1372 ext2_debug("using block group %d(%d)\n",
1373 group_no, gdp->bg_free_blocks_count);
1374
1375 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1376
1377 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1378 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1379 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1380 EXT2_SB(sb)->s_itb_per_group) ||
1381 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1382 EXT2_SB(sb)->s_itb_per_group)) {
1383 ext2_error(sb, "ext2_new_blocks",
1384 "Allocating block in system zone - "
1385 "blocks from "E2FSBLK", length %lu",
1386 ret_block, num);
1387 /*
1388 * ext2_try_to_allocate marked the blocks we allocated as in
1389 * use. So we may want to selectively mark some of the blocks
1390 * as free
1391 */
1392 num = *count;
1393 goto retry_alloc;
1394 }
1395
1396 performed_allocation = 1;
1397
1398 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1399 ext2_error(sb, "ext2_new_blocks",
1400 "block("E2FSBLK") >= blocks count(%d) - "
1401 "block_group = %d, es == %p ", ret_block,
1402 le32_to_cpu(es->s_blocks_count), group_no, es);
1403 goto out;
1404 }
1405
1406 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1407 percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1408
1409 mark_buffer_dirty(bitmap_bh);
1410 if (sb->s_flags & SB_SYNCHRONOUS)
1411 sync_dirty_buffer(bitmap_bh);
1412
1413 *errp = 0;
1414 brelse(bitmap_bh);
1415 if (num < *count) {
1416 dquot_free_block_nodirty(inode, *count-num);
1417 mark_inode_dirty(inode);
1418 *count = num;
1419 }
1420 return ret_block;
1421
1422 io_error:
1423 *errp = -EIO;
1424 out:
1425 /*
1426 * Undo the block allocation
1427 */
1428 if (!performed_allocation) {
1429 dquot_free_block_nodirty(inode, *count);
1430 mark_inode_dirty(inode);
1431 }
1432 brelse(bitmap_bh);
1433 return 0;
1434 }
1435
1436 #ifdef EXT2FS_DEBUG
1437
1438 unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
1439 {
1440 return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
1441 }
1442
1443 #endif /* EXT2FS_DEBUG */
1444
1445 unsigned long ext2_count_free_blocks (struct super_block * sb)
1446 {
1447 struct ext2_group_desc * desc;
1448 unsigned long desc_count = 0;
1449 int i;
1450 #ifdef EXT2FS_DEBUG
1451 unsigned long bitmap_count, x;
1452 struct ext2_super_block *es;
1453
1454 es = EXT2_SB(sb)->s_es;
1455 desc_count = 0;
1456 bitmap_count = 0;
1457 desc = NULL;
1458 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1459 struct buffer_head *bitmap_bh;
1460 desc = ext2_get_group_desc (sb, i, NULL);
1461 if (!desc)
1462 continue;
1463 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1464 bitmap_bh = read_block_bitmap(sb, i);
1465 if (!bitmap_bh)
1466 continue;
1467
1468 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1469 printk ("group %d: stored = %d, counted = %lu\n",
1470 i, le16_to_cpu(desc->bg_free_blocks_count), x);
1471 bitmap_count += x;
1472 brelse(bitmap_bh);
1473 }
1474 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1475 (long)le32_to_cpu(es->s_free_blocks_count),
1476 desc_count, bitmap_count);
1477 return bitmap_count;
1478 #else
1479 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1480 desc = ext2_get_group_desc(sb, i, NULL);
1481 if (!desc)
1482 continue;
1483 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1484 }
1485 return desc_count;
1486 #endif
1487 }
1488
1489 static inline int test_root(int a, int b)
1490 {
1491 int num = b;
1492
1493 while (a > num)
1494 num *= b;
1495 return num == a;
1496 }
1497
1498 static int ext2_group_sparse(int group)
1499 {
1500 if (group <= 1)
1501 return 1;
1502 return (test_root(group, 3) || test_root(group, 5) ||
1503 test_root(group, 7));
1504 }
1505
1506 /**
1507 * ext2_bg_has_super - number of blocks used by the superblock in group
1508 * @sb: superblock for filesystem
1509 * @group: group number to check
1510 *
1511 * Return the number of blocks used by the superblock (primary or backup)
1512 * in this group. Currently this will be only 0 or 1.
1513 */
1514 int ext2_bg_has_super(struct super_block *sb, int group)
1515 {
1516 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1517 !ext2_group_sparse(group))
1518 return 0;
1519 return 1;
1520 }
1521
1522 /**
1523 * ext2_bg_num_gdb - number of blocks used by the group table in group
1524 * @sb: superblock for filesystem
1525 * @group: group number to check
1526 *
1527 * Return the number of blocks used by the group descriptor table
1528 * (primary or backup) in this group. In the future there may be a
1529 * different number of descriptor blocks in each group.
1530 */
1531 unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1532 {
1533 return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1534 }
1535
1536
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