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 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
40
41 struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
42 unsigned int block_group,
43 struct buffer_head ** bh)
44 {
45 unsigned long group_desc;
46 unsigned long offset;
47 struct ext2_group_desc * desc;
48 struct ext2_sb_info *sbi = EXT2_SB(sb);
49
50 if (block_group >= sbi->s_groups_count) {
51 ext2_error (sb, "ext2_get_group_desc",
52 "block_group >= groups_count - "
53 "block_group = %d, groups_count = %lu",
54 block_group, sbi->s_groups_count);
55
56 return NULL;
57 }
58
59 group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
60 offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
61 if (!sbi->s_group_desc[group_desc]) {
62 ext2_error (sb, "ext2_get_group_desc",
63 "Group descriptor not loaded - "
64 "block_group = %d, group_desc = %lu, desc = %lu",
65 block_group, group_desc, offset);
66 return NULL;
67 }
68
69 desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;
70 if (bh)
71 *bh = sbi->s_group_desc[group_desc];
72 return desc + offset;
73 }
74
75 static int ext2_valid_block_bitmap(struct super_block *sb,
76 struct ext2_group_desc *desc,
77 unsigned int block_group,
78 struct buffer_head *bh)
79 {
80 ext2_grpblk_t offset;
81 ext2_grpblk_t next_zero_bit;
82 ext2_fsblk_t bitmap_blk;
83 ext2_fsblk_t group_first_block;
84
85 group_first_block = ext2_group_first_block_no(sb, block_group);
86
87 /* check whether block bitmap block number is set */
88 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
89 offset = bitmap_blk - group_first_block;
90 if (!ext2_test_bit(offset, bh->b_data))
91 /* bad block bitmap */
92 goto err_out;
93
94 /* check whether the inode bitmap block number is set */
95 bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
96 offset = bitmap_blk - group_first_block;
97 if (!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 next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
105 offset + EXT2_SB(sb)->s_itb_per_group,
106 offset);
107 if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
108 /* good bitmap for inode tables */
109 return 1;
110
111 err_out:
112 ext2_error(sb, __func__,
113 "Invalid block bitmap - "
114 "block_group = %d, block = %lu",
115 block_group, bitmap_blk);
116 return 0;
117 }
118
119 /*
120 * Read the bitmap for a given block_group,and validate the
121 * bits for block/inode/inode tables are set in the bitmaps
122 *
123 * Return buffer_head on success or NULL in case of failure.
124 */
125 static struct buffer_head *
126 read_block_bitmap(struct super_block *sb, unsigned int block_group)
127 {
128 struct ext2_group_desc * desc;
129 struct buffer_head * bh = NULL;
130 ext2_fsblk_t bitmap_blk;
131
132 desc = ext2_get_group_desc(sb, block_group, NULL);
133 if (!desc)
134 return NULL;
135 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
136 bh = sb_getblk(sb, bitmap_blk);
137 if (unlikely(!bh)) {
138 ext2_error(sb, __func__,
139 "Cannot read block bitmap - "
140 "block_group = %d, block_bitmap = %u",
141 block_group, le32_to_cpu(desc->bg_block_bitmap));
142 return NULL;
143 }
144 if (likely(bh_uptodate_or_lock(bh)))
145 return bh;
146
147 if (bh_submit_read(bh) < 0) {
148 brelse(bh);
149 ext2_error(sb, __func__,
150 "Cannot read block bitmap - "
151 "block_group = %d, block_bitmap = %u",
152 block_group, le32_to_cpu(desc->bg_block_bitmap));
153 return NULL;
154 }
155
156 ext2_valid_block_bitmap(sb, desc, block_group, bh);
157 /*
158 * file system mounted not to panic on error, continue with corrupt
159 * bitmap
160 */
161 return bh;
162 }
163
164 static void group_adjust_blocks(struct super_block *sb, int group_no,
165 struct ext2_group_desc *desc, struct buffer_head *bh, int count)
166 {
167 if (count) {
168 struct ext2_sb_info *sbi = EXT2_SB(sb);
169 unsigned free_blocks;
170
171 spin_lock(sb_bgl_lock(sbi, group_no));
172 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
173 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
174 spin_unlock(sb_bgl_lock(sbi, group_no));
175 mark_buffer_dirty(bh);
176 }
177 }
178
179 /*
180 * The reservation window structure operations
181 * --------------------------------------------
182 * Operations include:
183 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
184 *
185 * We use a red-black tree to represent per-filesystem reservation
186 * windows.
187 *
188 */
189
190 /**
191 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
192 * @rb_root: root of per-filesystem reservation rb tree
193 * @verbose: verbose mode
194 * @fn: function which wishes to dump the reservation map
195 *
196 * If verbose is turned on, it will print the whole block reservation
197 * windows(start, end). Otherwise, it will only print out the "bad" windows,
198 * those windows that overlap with their immediate neighbors.
199 */
200 #if 1
201 static void __rsv_window_dump(struct rb_root *root, int verbose,
202 const char *fn)
203 {
204 struct rb_node *n;
205 struct ext2_reserve_window_node *rsv, *prev;
206 int bad;
207
208 restart:
209 n = rb_first(root);
210 bad = 0;
211 prev = NULL;
212
213 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
214 while (n) {
215 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
216 if (verbose)
217 printk("reservation window 0x%p "
218 "start: %lu, end: %lu\n",
219 rsv, rsv->rsv_start, rsv->rsv_end);
220 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
221 printk("Bad reservation %p (start >= end)\n",
222 rsv);
223 bad = 1;
224 }
225 if (prev && prev->rsv_end >= rsv->rsv_start) {
226 printk("Bad reservation %p (prev->end >= start)\n",
227 rsv);
228 bad = 1;
229 }
230 if (bad) {
231 if (!verbose) {
232 printk("Restarting reservation walk in verbose mode\n");
233 verbose = 1;
234 goto restart;
235 }
236 }
237 n = rb_next(n);
238 prev = rsv;
239 }
240 printk("Window map complete.\n");
241 BUG_ON(bad);
242 }
243 #define rsv_window_dump(root, verbose) \
244 __rsv_window_dump((root), (verbose), __func__)
245 #else
246 #define rsv_window_dump(root, verbose) do {} while (0)
247 #endif
248
249 /**
250 * goal_in_my_reservation()
251 * @rsv: inode's reservation window
252 * @grp_goal: given goal block relative to the allocation block group
253 * @group: the current allocation block group
254 * @sb: filesystem super block
255 *
256 * Test if the given goal block (group relative) is within the file's
257 * own block reservation window range.
258 *
259 * If the reservation window is outside the goal allocation group, return 0;
260 * grp_goal (given goal block) could be -1, which means no specific
261 * goal block. In this case, always return 1.
262 * If the goal block is within the reservation window, return 1;
263 * otherwise, return 0;
264 */
265 static int
266 goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
267 unsigned int group, struct super_block * sb)
268 {
269 ext2_fsblk_t group_first_block, group_last_block;
270
271 group_first_block = ext2_group_first_block_no(sb, group);
272 group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
273
274 if ((rsv->_rsv_start > group_last_block) ||
275 (rsv->_rsv_end < group_first_block))
276 return 0;
277 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
278 || (grp_goal + group_first_block > rsv->_rsv_end)))
279 return 0;
280 return 1;
281 }
282
283 /**
284 * search_reserve_window()
285 * @rb_root: root of reservation tree
286 * @goal: target allocation block
287 *
288 * Find the reserved window which includes the goal, or the previous one
289 * if the goal is not in any window.
290 * Returns NULL if there are no windows or if all windows start after the goal.
291 */
292 static struct ext2_reserve_window_node *
293 search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
294 {
295 struct rb_node *n = root->rb_node;
296 struct ext2_reserve_window_node *rsv;
297
298 if (!n)
299 return NULL;
300
301 do {
302 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
303
304 if (goal < rsv->rsv_start)
305 n = n->rb_left;
306 else if (goal > rsv->rsv_end)
307 n = n->rb_right;
308 else
309 return rsv;
310 } while (n);
311 /*
312 * We've fallen off the end of the tree: the goal wasn't inside
313 * any particular node. OK, the previous node must be to one
314 * side of the interval containing the goal. If it's the RHS,
315 * we need to back up one.
316 */
317 if (rsv->rsv_start > goal) {
318 n = rb_prev(&rsv->rsv_node);
319 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
320 }
321 return rsv;
322 }
323
324 /*
325 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
326 * @sb: super block
327 * @rsv: reservation window to add
328 *
329 * Must be called with rsv_lock held.
330 */
331 void ext2_rsv_window_add(struct super_block *sb,
332 struct ext2_reserve_window_node *rsv)
333 {
334 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
335 struct rb_node *node = &rsv->rsv_node;
336 ext2_fsblk_t start = rsv->rsv_start;
337
338 struct rb_node ** p = &root->rb_node;
339 struct rb_node * parent = NULL;
340 struct ext2_reserve_window_node *this;
341
342 while (*p)
343 {
344 parent = *p;
345 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
346
347 if (start < this->rsv_start)
348 p = &(*p)->rb_left;
349 else if (start > this->rsv_end)
350 p = &(*p)->rb_right;
351 else {
352 rsv_window_dump(root, 1);
353 BUG();
354 }
355 }
356
357 rb_link_node(node, parent, p);
358 rb_insert_color(node, root);
359 }
360
361 /**
362 * rsv_window_remove() -- unlink a window from the reservation rb tree
363 * @sb: super block
364 * @rsv: reservation window to remove
365 *
366 * Mark the block reservation window as not allocated, and unlink it
367 * from the filesystem reservation window rb tree. Must be called with
368 * rsv_lock held.
369 */
370 static void rsv_window_remove(struct super_block *sb,
371 struct ext2_reserve_window_node *rsv)
372 {
373 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
374 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
375 rsv->rsv_alloc_hit = 0;
376 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
377 }
378
379 /*
380 * rsv_is_empty() -- Check if the reservation window is allocated.
381 * @rsv: given reservation window to check
382 *
383 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
384 */
385 static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
386 {
387 /* a valid reservation end block could not be 0 */
388 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
389 }
390
391 /**
392 * ext2_init_block_alloc_info()
393 * @inode: file inode structure
394 *
395 * Allocate and initialize the reservation window structure, and
396 * link the window to the ext2 inode structure at last
397 *
398 * The reservation window structure is only dynamically allocated
399 * and linked to ext2 inode the first time the open file
400 * needs a new block. So, before every ext2_new_block(s) call, for
401 * regular files, we should check whether the reservation window
402 * structure exists or not. In the latter case, this function is called.
403 * Fail to do so will result in block reservation being turned off for that
404 * open file.
405 *
406 * This function is called from ext2_get_blocks_handle(), also called
407 * when setting the reservation window size through ioctl before the file
408 * is open for write (needs block allocation).
409 *
410 * Needs truncate_mutex protection prior to calling this function.
411 */
412 void ext2_init_block_alloc_info(struct inode *inode)
413 {
414 struct ext2_inode_info *ei = EXT2_I(inode);
415 struct ext2_block_alloc_info *block_i;
416 struct super_block *sb = inode->i_sb;
417
418 block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
419 if (block_i) {
420 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
421
422 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
423 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
424
425 /*
426 * if filesystem is mounted with NORESERVATION, the goal
427 * reservation window size is set to zero to indicate
428 * block reservation is off
429 */
430 if (!test_opt(sb, RESERVATION))
431 rsv->rsv_goal_size = 0;
432 else
433 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
434 rsv->rsv_alloc_hit = 0;
435 block_i->last_alloc_logical_block = 0;
436 block_i->last_alloc_physical_block = 0;
437 }
438 ei->i_block_alloc_info = block_i;
439 }
440
441 /**
442 * ext2_discard_reservation()
443 * @inode: inode
444 *
445 * Discard(free) block reservation window on last file close, or truncate
446 * or at last iput().
447 *
448 * It is being called in three cases:
449 * ext2_release_file(): last writer closes the file
450 * ext2_clear_inode(): last iput(), when nobody links to this file.
451 * ext2_truncate(): when the block indirect map is about to change.
452 */
453 void ext2_discard_reservation(struct inode *inode)
454 {
455 struct ext2_inode_info *ei = EXT2_I(inode);
456 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
457 struct ext2_reserve_window_node *rsv;
458 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
459
460 if (!block_i)
461 return;
462
463 rsv = &block_i->rsv_window_node;
464 if (!rsv_is_empty(&rsv->rsv_window)) {
465 spin_lock(rsv_lock);
466 if (!rsv_is_empty(&rsv->rsv_window))
467 rsv_window_remove(inode->i_sb, rsv);
468 spin_unlock(rsv_lock);
469 }
470 }
471
472 /**
473 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks
474 * @inode: inode
475 * @block: start physical block to free
476 * @count: number of blocks to free
477 */
478 void ext2_free_blocks (struct inode * inode, unsigned long block,
479 unsigned long count)
480 {
481 struct buffer_head *bitmap_bh = NULL;
482 struct buffer_head * bh2;
483 unsigned long block_group;
484 unsigned long bit;
485 unsigned long i;
486 unsigned long overflow;
487 struct super_block * sb = inode->i_sb;
488 struct ext2_sb_info * sbi = EXT2_SB(sb);
489 struct ext2_group_desc * desc;
490 struct ext2_super_block * es = sbi->s_es;
491 unsigned freed = 0, group_freed;
492
493 if (!ext2_data_block_valid(sbi, block, count)) {
494 ext2_error (sb, "ext2_free_blocks",
495 "Freeing blocks not in datazone - "
496 "block = %lu, count = %lu", block, count);
497 goto error_return;
498 }
499
500 ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
501
502 do_more:
503 overflow = 0;
504 block_group = (block - le32_to_cpu(es->s_first_data_block)) /
505 EXT2_BLOCKS_PER_GROUP(sb);
506 bit = (block - le32_to_cpu(es->s_first_data_block)) %
507 EXT2_BLOCKS_PER_GROUP(sb);
508 /*
509 * Check to see if we are freeing blocks across a group
510 * boundary.
511 */
512 if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
513 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
514 count -= overflow;
515 }
516 brelse(bitmap_bh);
517 bitmap_bh = read_block_bitmap(sb, block_group);
518 if (!bitmap_bh)
519 goto error_return;
520
521 desc = ext2_get_group_desc (sb, block_group, &bh2);
522 if (!desc)
523 goto error_return;
524
525 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
526 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
527 in_range (block, le32_to_cpu(desc->bg_inode_table),
528 sbi->s_itb_per_group) ||
529 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
530 sbi->s_itb_per_group)) {
531 ext2_error (sb, "ext2_free_blocks",
532 "Freeing blocks in system zones - "
533 "Block = %lu, count = %lu",
534 block, count);
535 goto error_return;
536 }
537
538 for (i = 0, group_freed = 0; i < count; i++) {
539 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
540 bit + i, bitmap_bh->b_data)) {
541 ext2_error(sb, __func__,
542 "bit already cleared for block %lu", block + i);
543 } else {
544 group_freed++;
545 }
546 }
547
548 mark_buffer_dirty(bitmap_bh);
549 if (sb->s_flags & SB_SYNCHRONOUS)
550 sync_dirty_buffer(bitmap_bh);
551
552 group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
553 freed += group_freed;
554
555 if (overflow) {
556 block += count;
557 count = overflow;
558 goto do_more;
559 }
560 error_return:
561 brelse(bitmap_bh);
562 if (freed) {
563 percpu_counter_add(&sbi->s_freeblocks_counter, freed);
564 dquot_free_block_nodirty(inode, freed);
565 mark_inode_dirty(inode);
566 }
567 }
568
569 /**
570 * bitmap_search_next_usable_block()
571 * @start: the starting block (group relative) of the search
572 * @bh: bufferhead contains the block group bitmap
573 * @maxblocks: the ending block (group relative) of the reservation
574 *
575 * The bitmap search --- search forward through the actual bitmap on disk until
576 * we find a bit free.
577 */
578 static ext2_grpblk_t
579 bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
580 ext2_grpblk_t maxblocks)
581 {
582 ext2_grpblk_t next;
583
584 next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
585 if (next >= maxblocks)
586 return -1;
587 return next;
588 }
589
590 /**
591 * find_next_usable_block()
592 * @start: the starting block (group relative) to find next
593 * allocatable block in bitmap.
594 * @bh: bufferhead contains the block group bitmap
595 * @maxblocks: the ending block (group relative) for the search
596 *
597 * Find an allocatable block in a bitmap. We perform the "most
598 * appropriate allocation" algorithm of looking for a free block near
599 * the initial goal; then for a free byte somewhere in the bitmap;
600 * then for any free bit in the bitmap.
601 */
602 static ext2_grpblk_t
603 find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
604 {
605 ext2_grpblk_t here, next;
606 char *p, *r;
607
608 if (start > 0) {
609 /*
610 * The goal was occupied; search forward for a free
611 * block within the next XX blocks.
612 *
613 * end_goal is more or less random, but it has to be
614 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
615 * next 64-bit boundary is simple..
616 */
617 ext2_grpblk_t end_goal = (start + 63) & ~63;
618 if (end_goal > maxblocks)
619 end_goal = maxblocks;
620 here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
621 if (here < end_goal)
622 return here;
623 ext2_debug("Bit not found near goal\n");
624 }
625
626 here = start;
627 if (here < 0)
628 here = 0;
629
630 p = ((char *)bh->b_data) + (here >> 3);
631 r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
632 next = (r - ((char *)bh->b_data)) << 3;
633
634 if (next < maxblocks && next >= here)
635 return next;
636
637 here = bitmap_search_next_usable_block(here, bh, maxblocks);
638 return here;
639 }
640
641 /**
642 * ext2_try_to_allocate()
643 * @sb: superblock
644 * @group: given allocation block group
645 * @bitmap_bh: bufferhead holds the block bitmap
646 * @grp_goal: given target block within the group
647 * @count: target number of blocks to allocate
648 * @my_rsv: reservation window
649 *
650 * Attempt to allocate blocks within a give range. Set the range of allocation
651 * first, then find the first free bit(s) from the bitmap (within the range),
652 * and at last, allocate the blocks by claiming the found free bit as allocated.
653 *
654 * To set the range of this allocation:
655 * if there is a reservation window, only try to allocate block(s)
656 * from the file's own reservation window;
657 * Otherwise, the allocation range starts from the give goal block,
658 * ends at the block group's last block.
659 *
660 * If we failed to allocate the desired block then we may end up crossing to a
661 * new bitmap.
662 */
663 static int
664 ext2_try_to_allocate(struct super_block *sb, int group,
665 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
666 unsigned long *count,
667 struct ext2_reserve_window *my_rsv)
668 {
669 ext2_fsblk_t group_first_block;
670 ext2_grpblk_t start, end;
671 unsigned long num = 0;
672
673 /* we do allocation within the reservation window if we have a window */
674 if (my_rsv) {
675 group_first_block = ext2_group_first_block_no(sb, group);
676 if (my_rsv->_rsv_start >= group_first_block)
677 start = my_rsv->_rsv_start - group_first_block;
678 else
679 /* reservation window cross group boundary */
680 start = 0;
681 end = my_rsv->_rsv_end - group_first_block + 1;
682 if (end > EXT2_BLOCKS_PER_GROUP(sb))
683 /* reservation window crosses group boundary */
684 end = EXT2_BLOCKS_PER_GROUP(sb);
685 if ((start <= grp_goal) && (grp_goal < end))
686 start = grp_goal;
687 else
688 grp_goal = -1;
689 } else {
690 if (grp_goal > 0)
691 start = grp_goal;
692 else
693 start = 0;
694 end = EXT2_BLOCKS_PER_GROUP(sb);
695 }
696
697 BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
698
699 repeat:
700 if (grp_goal < 0) {
701 grp_goal = find_next_usable_block(start, bitmap_bh, end);
702 if (grp_goal < 0)
703 goto fail_access;
704 if (!my_rsv) {
705 int i;
706
707 for (i = 0; i < 7 && grp_goal > start &&
708 !ext2_test_bit(grp_goal - 1,
709 bitmap_bh->b_data);
710 i++, grp_goal--)
711 ;
712 }
713 }
714 start = grp_goal;
715
716 if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
717 bitmap_bh->b_data)) {
718 /*
719 * The block was allocated by another thread, or it was
720 * allocated and then freed by another thread
721 */
722 start++;
723 grp_goal++;
724 if (start >= end)
725 goto fail_access;
726 goto repeat;
727 }
728 num++;
729 grp_goal++;
730 while (num < *count && grp_goal < end
731 && !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
732 grp_goal, bitmap_bh->b_data)) {
733 num++;
734 grp_goal++;
735 }
736 *count = num;
737 return grp_goal - num;
738 fail_access:
739 *count = num;
740 return -1;
741 }
742
743 /**
744 * find_next_reservable_window():
745 * find a reservable space within the given range.
746 * It does not allocate the reservation window for now:
747 * alloc_new_reservation() will do the work later.
748 *
749 * @search_head: the head of the searching list;
750 * This is not necessarily the list head of the whole filesystem
751 *
752 * We have both head and start_block to assist the search
753 * for the reservable space. The list starts from head,
754 * but we will shift to the place where start_block is,
755 * then start from there, when looking for a reservable space.
756 *
757 * @size: the target new reservation window size
758 *
759 * @group_first_block: the first block we consider to start
760 * the real search from
761 *
762 * @last_block:
763 * the maximum block number that our goal reservable space
764 * could start from. This is normally the last block in this
765 * group. The search will end when we found the start of next
766 * possible reservable space is out of this boundary.
767 * This could handle the cross boundary reservation window
768 * request.
769 *
770 * basically we search from the given range, rather than the whole
771 * reservation double linked list, (start_block, last_block)
772 * to find a free region that is of my size and has not
773 * been reserved.
774 *
775 */
776 static int find_next_reservable_window(
777 struct ext2_reserve_window_node *search_head,
778 struct ext2_reserve_window_node *my_rsv,
779 struct super_block * sb,
780 ext2_fsblk_t start_block,
781 ext2_fsblk_t last_block)
782 {
783 struct rb_node *next;
784 struct ext2_reserve_window_node *rsv, *prev;
785 ext2_fsblk_t cur;
786 int size = my_rsv->rsv_goal_size;
787
788 /* TODO: make the start of the reservation window byte-aligned */
789 /* cur = *start_block & ~7;*/
790 cur = start_block;
791 rsv = search_head;
792 if (!rsv)
793 return -1;
794
795 while (1) {
796 if (cur <= rsv->rsv_end)
797 cur = rsv->rsv_end + 1;
798
799 /* TODO?
800 * in the case we could not find a reservable space
801 * that is what is expected, during the re-search, we could
802 * remember what's the largest reservable space we could have
803 * and return that one.
804 *
805 * For now it will fail if we could not find the reservable
806 * space with expected-size (or more)...
807 */
808 if (cur > last_block)
809 return -1; /* fail */
810
811 prev = rsv;
812 next = rb_next(&rsv->rsv_node);
813 rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
814
815 /*
816 * Reached the last reservation, we can just append to the
817 * previous one.
818 */
819 if (!next)
820 break;
821
822 if (cur + size <= rsv->rsv_start) {
823 /*
824 * Found a reserveable space big enough. We could
825 * have a reservation across the group boundary here
826 */
827 break;
828 }
829 }
830 /*
831 * we come here either :
832 * when we reach the end of the whole list,
833 * and there is empty reservable space after last entry in the list.
834 * append it to the end of the list.
835 *
836 * or we found one reservable space in the middle of the list,
837 * return the reservation window that we could append to.
838 * succeed.
839 */
840
841 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
842 rsv_window_remove(sb, my_rsv);
843
844 /*
845 * Let's book the whole available window for now. We will check the
846 * disk bitmap later and then, if there are free blocks then we adjust
847 * the window size if it's larger than requested.
848 * Otherwise, we will remove this node from the tree next time
849 * call find_next_reservable_window.
850 */
851 my_rsv->rsv_start = cur;
852 my_rsv->rsv_end = cur + size - 1;
853 my_rsv->rsv_alloc_hit = 0;
854
855 if (prev != my_rsv)
856 ext2_rsv_window_add(sb, my_rsv);
857
858 return 0;
859 }
860
861 /**
862 * alloc_new_reservation()--allocate a new reservation window
863 *
864 * To make a new reservation, we search part of the filesystem
865 * reservation list (the list that inside the group). We try to
866 * allocate a new reservation window near the allocation goal,
867 * or the beginning of the group, if there is no goal.
868 *
869 * We first find a reservable space after the goal, then from
870 * there, we check the bitmap for the first free block after
871 * it. If there is no free block until the end of group, then the
872 * whole group is full, we failed. Otherwise, check if the free
873 * block is inside the expected reservable space, if so, we
874 * succeed.
875 * If the first free block is outside the reservable space, then
876 * start from the first free block, we search for next available
877 * space, and go on.
878 *
879 * on succeed, a new reservation will be found and inserted into the list
880 * It contains at least one free block, and it does not overlap with other
881 * reservation windows.
882 *
883 * failed: we failed to find a reservation window in this group
884 *
885 * @rsv: the reservation
886 *
887 * @grp_goal: The goal (group-relative). It is where the search for a
888 * free reservable space should start from.
889 * if we have a goal(goal >0 ), then start from there,
890 * no goal(goal = -1), we start from the first block
891 * of the group.
892 *
893 * @sb: the super block
894 * @group: the group we are trying to allocate in
895 * @bitmap_bh: the block group block bitmap
896 *
897 */
898 static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
899 ext2_grpblk_t grp_goal, struct super_block *sb,
900 unsigned int group, struct buffer_head *bitmap_bh)
901 {
902 struct ext2_reserve_window_node *search_head;
903 ext2_fsblk_t group_first_block, group_end_block, start_block;
904 ext2_grpblk_t first_free_block;
905 struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
906 unsigned long size;
907 int ret;
908 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
909
910 group_first_block = ext2_group_first_block_no(sb, group);
911 group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
912
913 if (grp_goal < 0)
914 start_block = group_first_block;
915 else
916 start_block = grp_goal + group_first_block;
917
918 size = my_rsv->rsv_goal_size;
919
920 if (!rsv_is_empty(&my_rsv->rsv_window)) {
921 /*
922 * if the old reservation is cross group boundary
923 * and if the goal is inside the old reservation window,
924 * we will come here when we just failed to allocate from
925 * the first part of the window. We still have another part
926 * that belongs to the next group. In this case, there is no
927 * point to discard our window and try to allocate a new one
928 * in this group(which will fail). we should
929 * keep the reservation window, just simply move on.
930 *
931 * Maybe we could shift the start block of the reservation
932 * window to the first block of next group.
933 */
934
935 if ((my_rsv->rsv_start <= group_end_block) &&
936 (my_rsv->rsv_end > group_end_block) &&
937 (start_block >= my_rsv->rsv_start))
938 return -1;
939
940 if ((my_rsv->rsv_alloc_hit >
941 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
942 /*
943 * if the previously allocation hit ratio is
944 * greater than 1/2, then we double the size of
945 * the reservation window the next time,
946 * otherwise we keep the same size window
947 */
948 size = size * 2;
949 if (size > EXT2_MAX_RESERVE_BLOCKS)
950 size = EXT2_MAX_RESERVE_BLOCKS;
951 my_rsv->rsv_goal_size= size;
952 }
953 }
954
955 spin_lock(rsv_lock);
956 /*
957 * shift the search start to the window near the goal block
958 */
959 search_head = search_reserve_window(fs_rsv_root, start_block);
960
961 /*
962 * find_next_reservable_window() simply finds a reservable window
963 * inside the given range(start_block, group_end_block).
964 *
965 * To make sure the reservation window has a free bit inside it, we
966 * need to check the bitmap after we found a reservable window.
967 */
968 retry:
969 ret = find_next_reservable_window(search_head, my_rsv, sb,
970 start_block, group_end_block);
971
972 if (ret == -1) {
973 if (!rsv_is_empty(&my_rsv->rsv_window))
974 rsv_window_remove(sb, my_rsv);
975 spin_unlock(rsv_lock);
976 return -1;
977 }
978
979 /*
980 * On success, find_next_reservable_window() returns the
981 * reservation window where there is a reservable space after it.
982 * Before we reserve this reservable space, we need
983 * to make sure there is at least a free block inside this region.
984 *
985 * Search the first free bit on the block bitmap. Search starts from
986 * the start block of the reservable space we just found.
987 */
988 spin_unlock(rsv_lock);
989 first_free_block = bitmap_search_next_usable_block(
990 my_rsv->rsv_start - group_first_block,
991 bitmap_bh, group_end_block - group_first_block + 1);
992
993 if (first_free_block < 0) {
994 /*
995 * no free block left on the bitmap, no point
996 * to reserve the space. return failed.
997 */
998 spin_lock(rsv_lock);
999 if (!rsv_is_empty(&my_rsv->rsv_window))
1000 rsv_window_remove(sb, my_rsv);
1001 spin_unlock(rsv_lock);
1002 return -1; /* failed */
1003 }
1004
1005 start_block = first_free_block + group_first_block;
1006 /*
1007 * check if the first free block is within the
1008 * free space we just reserved
1009 */
1010 if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1011 return 0; /* success */
1012 /*
1013 * if the first free bit we found is out of the reservable space
1014 * continue search for next reservable space,
1015 * start from where the free block is,
1016 * we also shift the list head to where we stopped last time
1017 */
1018 search_head = my_rsv;
1019 spin_lock(rsv_lock);
1020 goto retry;
1021 }
1022
1023 /**
1024 * try_to_extend_reservation()
1025 * @my_rsv: given reservation window
1026 * @sb: super block
1027 * @size: the delta to extend
1028 *
1029 * Attempt to expand the reservation window large enough to have
1030 * required number of free blocks
1031 *
1032 * Since ext2_try_to_allocate() will always allocate blocks within
1033 * the reservation window range, if the window size is too small,
1034 * multiple blocks allocation has to stop at the end of the reservation
1035 * window. To make this more efficient, given the total number of
1036 * blocks needed and the current size of the window, we try to
1037 * expand the reservation window size if necessary on a best-effort
1038 * basis before ext2_new_blocks() tries to allocate blocks.
1039 */
1040 static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1041 struct super_block *sb, int size)
1042 {
1043 struct ext2_reserve_window_node *next_rsv;
1044 struct rb_node *next;
1045 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1046
1047 if (!spin_trylock(rsv_lock))
1048 return;
1049
1050 next = rb_next(&my_rsv->rsv_node);
1051
1052 if (!next)
1053 my_rsv->rsv_end += size;
1054 else {
1055 next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1056
1057 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1058 my_rsv->rsv_end += size;
1059 else
1060 my_rsv->rsv_end = next_rsv->rsv_start - 1;
1061 }
1062 spin_unlock(rsv_lock);
1063 }
1064
1065 /**
1066 * ext2_try_to_allocate_with_rsv()
1067 * @sb: superblock
1068 * @group: given allocation block group
1069 * @bitmap_bh: bufferhead holds the block bitmap
1070 * @grp_goal: given target block within the group
1071 * @count: target number of blocks to allocate
1072 * @my_rsv: reservation window
1073 *
1074 * This is the main function used to allocate a new block and its reservation
1075 * window.
1076 *
1077 * Each time when a new block allocation is need, first try to allocate from
1078 * its own reservation. If it does not have a reservation window, instead of
1079 * looking for a free bit on bitmap first, then look up the reservation list to
1080 * see if it is inside somebody else's reservation window, we try to allocate a
1081 * reservation window for it starting from the goal first. Then do the block
1082 * allocation within the reservation window.
1083 *
1084 * This will avoid keeping on searching the reservation list again and
1085 * again when somebody is looking for a free block (without
1086 * reservation), and there are lots of free blocks, but they are all
1087 * being reserved.
1088 *
1089 * We use a red-black tree for the per-filesystem reservation list.
1090 */
1091 static ext2_grpblk_t
1092 ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1093 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1094 struct ext2_reserve_window_node * my_rsv,
1095 unsigned long *count)
1096 {
1097 ext2_fsblk_t group_first_block, group_last_block;
1098 ext2_grpblk_t ret = 0;
1099 unsigned long num = *count;
1100
1101 /*
1102 * we don't deal with reservation when
1103 * filesystem is mounted without reservation
1104 * or the file is not a regular file
1105 * or last attempt to allocate a block with reservation turned on failed
1106 */
1107 if (my_rsv == NULL) {
1108 return ext2_try_to_allocate(sb, group, bitmap_bh,
1109 grp_goal, count, NULL);
1110 }
1111 /*
1112 * grp_goal is a group relative block number (if there is a goal)
1113 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1114 * first block is a filesystem wide block number
1115 * first block is the block number of the first block in this group
1116 */
1117 group_first_block = ext2_group_first_block_no(sb, group);
1118 group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
1119
1120 /*
1121 * Basically we will allocate a new block from inode's reservation
1122 * window.
1123 *
1124 * We need to allocate a new reservation window, if:
1125 * a) inode does not have a reservation window; or
1126 * b) last attempt to allocate a block from existing reservation
1127 * failed; or
1128 * c) we come here with a goal and with a reservation window
1129 *
1130 * We do not need to allocate a new reservation window if we come here
1131 * at the beginning with a goal and the goal is inside the window, or
1132 * we don't have a goal but already have a reservation window.
1133 * then we could go to allocate from the reservation window directly.
1134 */
1135 while (1) {
1136 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1137 !goal_in_my_reservation(&my_rsv->rsv_window,
1138 grp_goal, group, sb)) {
1139 if (my_rsv->rsv_goal_size < *count)
1140 my_rsv->rsv_goal_size = *count;
1141 ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1142 group, bitmap_bh);
1143 if (ret < 0)
1144 break; /* failed */
1145
1146 if (!goal_in_my_reservation(&my_rsv->rsv_window,
1147 grp_goal, group, sb))
1148 grp_goal = -1;
1149 } else if (grp_goal >= 0) {
1150 int curr = my_rsv->rsv_end -
1151 (grp_goal + group_first_block) + 1;
1152
1153 if (curr < *count)
1154 try_to_extend_reservation(my_rsv, sb,
1155 *count - curr);
1156 }
1157
1158 if ((my_rsv->rsv_start > group_last_block) ||
1159 (my_rsv->rsv_end < group_first_block)) {
1160 rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1161 BUG();
1162 }
1163 ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1164 &num, &my_rsv->rsv_window);
1165 if (ret >= 0) {
1166 my_rsv->rsv_alloc_hit += num;
1167 *count = num;
1168 break; /* succeed */
1169 }
1170 num = *count;
1171 }
1172 return ret;
1173 }
1174
1175 /**
1176 * ext2_has_free_blocks()
1177 * @sbi: in-core super block structure.
1178 *
1179 * Check if filesystem has at least 1 free block available for allocation.
1180 */
1181 static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1182 {
1183 ext2_fsblk_t free_blocks, root_blocks;
1184
1185 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1186 root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1187 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1188 !uid_eq(sbi->s_resuid, current_fsuid()) &&
1189 (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1190 !in_group_p (sbi->s_resgid))) {
1191 return 0;
1192 }
1193 return 1;
1194 }
1195
1196 /*
1197 * Returns 1 if the passed-in block region is valid; 0 if some part overlaps
1198 * with filesystem metadata blocks.
1199 */
1200 int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
1201 unsigned int count)
1202 {
1203 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
1204 (start_blk + count - 1 < start_blk) ||
1205 (start_blk + count - 1 >= le32_to_cpu(sbi->s_es->s_blocks_count)))
1206 return 0;
1207
1208 /* Ensure we do not step over superblock */
1209 if ((start_blk <= sbi->s_sb_block) &&
1210 (start_blk + count - 1 >= sbi->s_sb_block))
1211 return 0;
1212
1213 return 1;
1214 }
1215
1216 /*
1217 * ext2_new_blocks() -- core block(s) allocation function
1218 * @inode: file inode
1219 * @goal: given target block(filesystem wide)
1220 * @count: target number of blocks to allocate
1221 * @errp: error code
1222 *
1223 * ext2_new_blocks uses a goal block to assist allocation. If the goal is
1224 * free, or there is a free block within 32 blocks of the goal, that block
1225 * is allocated. Otherwise a forward search is made for a free block; within
1226 * each block group the search first looks for an entire free byte in the block
1227 * bitmap, and then for any free bit if that fails.
1228 * This function also updates quota and i_blocks field.
1229 */
1230 ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1231 unsigned long *count, int *errp)
1232 {
1233 struct buffer_head *bitmap_bh = NULL;
1234 struct buffer_head *gdp_bh;
1235 int group_no;
1236 int goal_group;
1237 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1238 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1239 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1240 int bgi; /* blockgroup iteration index */
1241 int performed_allocation = 0;
1242 ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1243 struct super_block *sb;
1244 struct ext2_group_desc *gdp;
1245 struct ext2_super_block *es;
1246 struct ext2_sb_info *sbi;
1247 struct ext2_reserve_window_node *my_rsv = NULL;
1248 struct ext2_block_alloc_info *block_i;
1249 unsigned short windowsz = 0;
1250 unsigned long ngroups;
1251 unsigned long num = *count;
1252 int ret;
1253
1254 *errp = -ENOSPC;
1255 sb = inode->i_sb;
1256
1257 /*
1258 * Check quota for allocation of this block.
1259 */
1260 ret = dquot_alloc_block(inode, num);
1261 if (ret) {
1262 *errp = ret;
1263 return 0;
1264 }
1265
1266 sbi = EXT2_SB(sb);
1267 es = EXT2_SB(sb)->s_es;
1268 ext2_debug("goal=%lu.\n", goal);
1269 /*
1270 * Allocate a block from reservation only when
1271 * filesystem is mounted with reservation(default,-o reservation), and
1272 * it's a regular file, and
1273 * the desired window size is greater than 0 (One could use ioctl
1274 * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1275 * reservation on that particular file)
1276 */
1277 block_i = EXT2_I(inode)->i_block_alloc_info;
1278 if (block_i) {
1279 windowsz = block_i->rsv_window_node.rsv_goal_size;
1280 if (windowsz > 0)
1281 my_rsv = &block_i->rsv_window_node;
1282 }
1283
1284 if (!ext2_has_free_blocks(sbi)) {
1285 *errp = -ENOSPC;
1286 goto out;
1287 }
1288
1289 /*
1290 * First, test whether the goal block is free.
1291 */
1292 if (goal < le32_to_cpu(es->s_first_data_block) ||
1293 goal >= le32_to_cpu(es->s_blocks_count))
1294 goal = le32_to_cpu(es->s_first_data_block);
1295 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1296 EXT2_BLOCKS_PER_GROUP(sb);
1297 goal_group = group_no;
1298 retry_alloc:
1299 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1300 if (!gdp)
1301 goto io_error;
1302
1303 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1304 /*
1305 * if there is not enough free blocks to make a new resevation
1306 * turn off reservation for this allocation
1307 */
1308 if (my_rsv && (free_blocks < windowsz)
1309 && (free_blocks > 0)
1310 && (rsv_is_empty(&my_rsv->rsv_window)))
1311 my_rsv = NULL;
1312
1313 if (free_blocks > 0) {
1314 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1315 EXT2_BLOCKS_PER_GROUP(sb));
1316 bitmap_bh = read_block_bitmap(sb, group_no);
1317 if (!bitmap_bh)
1318 goto io_error;
1319 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1320 bitmap_bh, grp_target_blk,
1321 my_rsv, &num);
1322 if (grp_alloc_blk >= 0)
1323 goto allocated;
1324 }
1325
1326 ngroups = EXT2_SB(sb)->s_groups_count;
1327 smp_rmb();
1328
1329 /*
1330 * Now search the rest of the groups. We assume that
1331 * group_no and gdp correctly point to the last group visited.
1332 */
1333 for (bgi = 0; bgi < ngroups; bgi++) {
1334 group_no++;
1335 if (group_no >= ngroups)
1336 group_no = 0;
1337 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1338 if (!gdp)
1339 goto io_error;
1340
1341 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1342 /*
1343 * skip this group (and avoid loading bitmap) if there
1344 * are no free blocks
1345 */
1346 if (!free_blocks)
1347 continue;
1348 /*
1349 * skip this group if the number of
1350 * free blocks is less than half of the reservation
1351 * window size.
1352 */
1353 if (my_rsv && (free_blocks <= (windowsz/2)))
1354 continue;
1355
1356 brelse(bitmap_bh);
1357 bitmap_bh = read_block_bitmap(sb, group_no);
1358 if (!bitmap_bh)
1359 goto io_error;
1360 /*
1361 * try to allocate block(s) from this group, without a goal(-1).
1362 */
1363 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1364 bitmap_bh, -1, my_rsv, &num);
1365 if (grp_alloc_blk >= 0)
1366 goto allocated;
1367 }
1368 /*
1369 * We may end up a bogus earlier ENOSPC error due to
1370 * filesystem is "full" of reservations, but
1371 * there maybe indeed free blocks available on disk
1372 * In this case, we just forget about the reservations
1373 * just do block allocation as without reservations.
1374 */
1375 if (my_rsv) {
1376 my_rsv = NULL;
1377 windowsz = 0;
1378 group_no = goal_group;
1379 goto retry_alloc;
1380 }
1381 /* No space left on the device */
1382 *errp = -ENOSPC;
1383 goto out;
1384
1385 allocated:
1386
1387 ext2_debug("using block group %d(%d)\n",
1388 group_no, gdp->bg_free_blocks_count);
1389
1390 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1391
1392 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1393 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1394 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1395 EXT2_SB(sb)->s_itb_per_group) ||
1396 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1397 EXT2_SB(sb)->s_itb_per_group)) {
1398 ext2_error(sb, "ext2_new_blocks",
1399 "Allocating block in system zone - "
1400 "blocks from "E2FSBLK", length %lu",
1401 ret_block, num);
1402 /*
1403 * ext2_try_to_allocate marked the blocks we allocated as in
1404 * use. So we may want to selectively mark some of the blocks
1405 * as free
1406 */
1407 goto retry_alloc;
1408 }
1409
1410 performed_allocation = 1;
1411
1412 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1413 ext2_error(sb, "ext2_new_blocks",
1414 "block("E2FSBLK") >= blocks count(%d) - "
1415 "block_group = %d, es == %p ", ret_block,
1416 le32_to_cpu(es->s_blocks_count), group_no, es);
1417 goto out;
1418 }
1419
1420 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1421 percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1422
1423 mark_buffer_dirty(bitmap_bh);
1424 if (sb->s_flags & SB_SYNCHRONOUS)
1425 sync_dirty_buffer(bitmap_bh);
1426
1427 *errp = 0;
1428 brelse(bitmap_bh);
1429 if (num < *count) {
1430 dquot_free_block_nodirty(inode, *count-num);
1431 mark_inode_dirty(inode);
1432 *count = num;
1433 }
1434 return ret_block;
1435
1436 io_error:
1437 *errp = -EIO;
1438 out:
1439 /*
1440 * Undo the block allocation
1441 */
1442 if (!performed_allocation) {
1443 dquot_free_block_nodirty(inode, *count);
1444 mark_inode_dirty(inode);
1445 }
1446 brelse(bitmap_bh);
1447 return 0;
1448 }
1449
1450 ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1451 {
1452 unsigned long count = 1;
1453
1454 return ext2_new_blocks(inode, goal, &count, errp);
1455 }
1456
1457 #ifdef EXT2FS_DEBUG
1458
1459 unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
1460 {
1461 return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
1462 }
1463
1464 #endif /* EXT2FS_DEBUG */
1465
1466 unsigned long ext2_count_free_blocks (struct super_block * sb)
1467 {
1468 struct ext2_group_desc * desc;
1469 unsigned long desc_count = 0;
1470 int i;
1471 #ifdef EXT2FS_DEBUG
1472 unsigned long bitmap_count, x;
1473 struct ext2_super_block *es;
1474
1475 es = EXT2_SB(sb)->s_es;
1476 desc_count = 0;
1477 bitmap_count = 0;
1478 desc = NULL;
1479 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1480 struct buffer_head *bitmap_bh;
1481 desc = ext2_get_group_desc (sb, i, NULL);
1482 if (!desc)
1483 continue;
1484 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1485 bitmap_bh = read_block_bitmap(sb, i);
1486 if (!bitmap_bh)
1487 continue;
1488
1489 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1490 printk ("group %d: stored = %d, counted = %lu\n",
1491 i, le16_to_cpu(desc->bg_free_blocks_count), x);
1492 bitmap_count += x;
1493 brelse(bitmap_bh);
1494 }
1495 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1496 (long)le32_to_cpu(es->s_free_blocks_count),
1497 desc_count, bitmap_count);
1498 return bitmap_count;
1499 #else
1500 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1501 desc = ext2_get_group_desc (sb, i, NULL);
1502 if (!desc)
1503 continue;
1504 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1505 }
1506 return desc_count;
1507 #endif
1508 }
1509
1510 static inline int test_root(int a, int b)
1511 {
1512 int num = b;
1513
1514 while (a > num)
1515 num *= b;
1516 return num == a;
1517 }
1518
1519 static int ext2_group_sparse(int group)
1520 {
1521 if (group <= 1)
1522 return 1;
1523 return (test_root(group, 3) || test_root(group, 5) ||
1524 test_root(group, 7));
1525 }
1526
1527 /**
1528 * ext2_bg_has_super - number of blocks used by the superblock in group
1529 * @sb: superblock for filesystem
1530 * @group: group number to check
1531 *
1532 * Return the number of blocks used by the superblock (primary or backup)
1533 * in this group. Currently this will be only 0 or 1.
1534 */
1535 int ext2_bg_has_super(struct super_block *sb, int group)
1536 {
1537 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1538 !ext2_group_sparse(group))
1539 return 0;
1540 return 1;
1541 }
1542
1543 /**
1544 * ext2_bg_num_gdb - number of blocks used by the group table in group
1545 * @sb: superblock for filesystem
1546 * @group: group number to check
1547 *
1548 * Return the number of blocks used by the group descriptor table
1549 * (primary or backup) in this group. In the future there may be a
1550 * different number of descriptor blocks in each group.
1551 */
1552 unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1553 {
1554 return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1555 }
1556