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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
39struct 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
71static 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
81 group_first_block = ext2_group_first_block_no(sb, block_group);
82
83 /* check whether block bitmap block number is set */
84 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
85 offset = bitmap_blk - group_first_block;
86 if (!ext2_test_bit(offset, bh->b_data))
87 /* bad block bitmap */
88 goto err_out;
89
90 /* check whether the inode bitmap block number is set */
91 bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
92 offset = bitmap_blk - group_first_block;
93 if (!ext2_test_bit(offset, bh->b_data))
94 /* bad block bitmap */
95 goto err_out;
96
97 /* check whether the inode table block number is set */
98 bitmap_blk = le32_to_cpu(desc->bg_inode_table);
99 offset = bitmap_blk - group_first_block;
100 next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
101 offset + EXT2_SB(sb)->s_itb_per_group,
102 offset);
103 if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
104 /* good bitmap for inode tables */
105 return 1;
106
107err_out:
108 ext2_error(sb, __func__,
109 "Invalid block bitmap - "
110 "block_group = %d, block = %lu",
111 block_group, bitmap_blk);
112 return 0;
113}
114
115/*
116 * Read the bitmap for a given block_group,and validate the
117 * bits for block/inode/inode tables are set in the bitmaps
118 *
119 * Return buffer_head on success or NULL in case of failure.
120 */
121static struct buffer_head *
122read_block_bitmap(struct super_block *sb, unsigned int block_group)
123{
124 struct ext2_group_desc * desc;
125 struct buffer_head * bh = NULL;
126 ext2_fsblk_t bitmap_blk;
127 int ret;
128
129 desc = ext2_get_group_desc(sb, block_group, NULL);
130 if (!desc)
131 return NULL;
132 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
133 bh = sb_getblk(sb, bitmap_blk);
134 if (unlikely(!bh)) {
135 ext2_error(sb, __func__,
136 "Cannot read block bitmap - "
137 "block_group = %d, block_bitmap = %u",
138 block_group, le32_to_cpu(desc->bg_block_bitmap));
139 return NULL;
140 }
141 ret = bh_read(bh, 0);
142 if (ret > 0)
143 return bh;
144 if (ret < 0) {
145 brelse(bh);
146 ext2_error(sb, __func__,
147 "Cannot read block bitmap - "
148 "block_group = %d, block_bitmap = %u",
149 block_group, le32_to_cpu(desc->bg_block_bitmap));
150 return NULL;
151 }
152
153 ext2_valid_block_bitmap(sb, desc, block_group, bh);
154 /*
155 * file system mounted not to panic on error, continue with corrupt
156 * bitmap
157 */
158 return bh;
159}
160
161static void group_adjust_blocks(struct super_block *sb, int group_no,
162 struct ext2_group_desc *desc, struct buffer_head *bh, int count)
163{
164 if (count) {
165 struct ext2_sb_info *sbi = EXT2_SB(sb);
166 unsigned free_blocks;
167
168 spin_lock(sb_bgl_lock(sbi, group_no));
169 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
170 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
171 spin_unlock(sb_bgl_lock(sbi, group_no));
172 mark_buffer_dirty(bh);
173 }
174}
175
176/*
177 * The reservation window structure operations
178 * --------------------------------------------
179 * Operations include:
180 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
181 *
182 * We use a red-black tree to represent per-filesystem reservation
183 * windows.
184 *
185 */
186
187/**
188 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
189 * @root: root of per-filesystem reservation rb tree
190 * @verbose: verbose mode
191 * @fn: function which wishes to dump the reservation map
192 *
193 * If verbose is turned on, it will print the whole block reservation
194 * windows(start, end). Otherwise, it will only print out the "bad" windows,
195 * those windows that overlap with their immediate neighbors.
196 */
197#if 1
198static void __rsv_window_dump(struct rb_root *root, int verbose,
199 const char *fn)
200{
201 struct rb_node *n;
202 struct ext2_reserve_window_node *rsv, *prev;
203 int bad;
204
205restart:
206 n = rb_first(root);
207 bad = 0;
208 prev = NULL;
209
210 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
211 while (n) {
212 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
213 if (verbose)
214 printk("reservation window 0x%p "
215 "start: %lu, end: %lu\n",
216 rsv, rsv->rsv_start, rsv->rsv_end);
217 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
218 printk("Bad reservation %p (start >= end)\n",
219 rsv);
220 bad = 1;
221 }
222 if (prev && prev->rsv_end >= rsv->rsv_start) {
223 printk("Bad reservation %p (prev->end >= start)\n",
224 rsv);
225 bad = 1;
226 }
227 if (bad) {
228 if (!verbose) {
229 printk("Restarting reservation walk in verbose mode\n");
230 verbose = 1;
231 goto restart;
232 }
233 }
234 n = rb_next(n);
235 prev = rsv;
236 }
237 printk("Window map complete.\n");
238 BUG_ON(bad);
239}
240#define rsv_window_dump(root, verbose) \
241 __rsv_window_dump((root), (verbose), __func__)
242#else
243#define rsv_window_dump(root, verbose) do {} while (0)
244#endif
245
246/**
247 * goal_in_my_reservation()
248 * @rsv: inode's reservation window
249 * @grp_goal: given goal block relative to the allocation block group
250 * @group: the current allocation block group
251 * @sb: filesystem super block
252 *
253 * Test if the given goal block (group relative) is within the file's
254 * own block reservation window range.
255 *
256 * If the reservation window is outside the goal allocation group, return 0;
257 * grp_goal (given goal block) could be -1, which means no specific
258 * goal block. In this case, always return 1.
259 * If the goal block is within the reservation window, return 1;
260 * otherwise, return 0;
261 */
262static int
263goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
264 unsigned int group, struct super_block * sb)
265{
266 ext2_fsblk_t group_first_block, group_last_block;
267
268 group_first_block = ext2_group_first_block_no(sb, group);
269 group_last_block = ext2_group_last_block_no(sb, group);
270
271 if ((rsv->_rsv_start > group_last_block) ||
272 (rsv->_rsv_end < group_first_block))
273 return 0;
274 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
275 || (grp_goal + group_first_block > rsv->_rsv_end)))
276 return 0;
277 return 1;
278}
279
280/**
281 * search_reserve_window()
282 * @root: root of reservation tree
283 * @goal: target allocation block
284 *
285 * Find the reserved window which includes the goal, or the previous one
286 * if the goal is not in any window.
287 * Returns NULL if there are no windows or if all windows start after the goal.
288 */
289static struct ext2_reserve_window_node *
290search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
291{
292 struct rb_node *n = root->rb_node;
293 struct ext2_reserve_window_node *rsv;
294
295 if (!n)
296 return NULL;
297
298 do {
299 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
300
301 if (goal < rsv->rsv_start)
302 n = n->rb_left;
303 else if (goal > rsv->rsv_end)
304 n = n->rb_right;
305 else
306 return rsv;
307 } while (n);
308 /*
309 * We've fallen off the end of the tree: the goal wasn't inside
310 * any particular node. OK, the previous node must be to one
311 * side of the interval containing the goal. If it's the RHS,
312 * we need to back up one.
313 */
314 if (rsv->rsv_start > goal) {
315 n = rb_prev(&rsv->rsv_node);
316 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
317 }
318 return rsv;
319}
320
321/*
322 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
323 * @sb: super block
324 * @rsv: reservation window to add
325 *
326 * Must be called with rsv_lock held.
327 */
328void ext2_rsv_window_add(struct super_block *sb,
329 struct ext2_reserve_window_node *rsv)
330{
331 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
332 struct rb_node *node = &rsv->rsv_node;
333 ext2_fsblk_t start = rsv->rsv_start;
334
335 struct rb_node ** p = &root->rb_node;
336 struct rb_node * parent = NULL;
337 struct ext2_reserve_window_node *this;
338
339 while (*p)
340 {
341 parent = *p;
342 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
343
344 if (start < this->rsv_start)
345 p = &(*p)->rb_left;
346 else if (start > this->rsv_end)
347 p = &(*p)->rb_right;
348 else {
349 rsv_window_dump(root, 1);
350 BUG();
351 }
352 }
353
354 rb_link_node(node, parent, p);
355 rb_insert_color(node, root);
356}
357
358/**
359 * rsv_window_remove() -- unlink a window from the reservation rb tree
360 * @sb: super block
361 * @rsv: reservation window to remove
362 *
363 * Mark the block reservation window as not allocated, and unlink it
364 * from the filesystem reservation window rb tree. Must be called with
365 * rsv_lock held.
366 */
367static void rsv_window_remove(struct super_block *sb,
368 struct ext2_reserve_window_node *rsv)
369{
370 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
371 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
372 rsv->rsv_alloc_hit = 0;
373 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
374}
375
376/*
377 * rsv_is_empty() -- Check if the reservation window is allocated.
378 * @rsv: given reservation window to check
379 *
380 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
381 */
382static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
383{
384 /* a valid reservation end block could not be 0 */
385 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
386}
387
388/**
389 * ext2_init_block_alloc_info()
390 * @inode: file inode structure
391 *
392 * Allocate and initialize the reservation window structure, and
393 * link the window to the ext2 inode structure at last
394 *
395 * The reservation window structure is only dynamically allocated
396 * and linked to ext2 inode the first time the open file
397 * needs a new block. So, before every ext2_new_block(s) call, for
398 * regular files, we should check whether the reservation window
399 * structure exists or not. In the latter case, this function is called.
400 * Fail to do so will result in block reservation being turned off for that
401 * open file.
402 *
403 * This function is called from ext2_get_blocks_handle(), also called
404 * when setting the reservation window size through ioctl before the file
405 * is open for write (needs block allocation).
406 *
407 * Needs truncate_mutex protection prior to calling this function.
408 */
409void ext2_init_block_alloc_info(struct inode *inode)
410{
411 struct ext2_inode_info *ei = EXT2_I(inode);
412 struct ext2_block_alloc_info *block_i;
413 struct super_block *sb = inode->i_sb;
414
415 block_i = kmalloc(sizeof(*block_i), GFP_KERNEL);
416 if (block_i) {
417 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
418
419 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
420 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
421
422 /*
423 * if filesystem is mounted with NORESERVATION, the goal
424 * reservation window size is set to zero to indicate
425 * block reservation is off
426 */
427 if (!test_opt(sb, RESERVATION))
428 rsv->rsv_goal_size = 0;
429 else
430 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
431 rsv->rsv_alloc_hit = 0;
432 block_i->last_alloc_logical_block = 0;
433 block_i->last_alloc_physical_block = 0;
434 }
435 ei->i_block_alloc_info = block_i;
436}
437
438/**
439 * ext2_discard_reservation()
440 * @inode: inode
441 *
442 * Discard(free) block reservation window on last file close, or truncate
443 * or at last iput().
444 *
445 * It is being called in three cases:
446 * ext2_release_file(): last writer closes the file
447 * ext2_clear_inode(): last iput(), when nobody links to this file.
448 * ext2_truncate(): when the block indirect map is about to change.
449 */
450void ext2_discard_reservation(struct inode *inode)
451{
452 struct ext2_inode_info *ei = EXT2_I(inode);
453 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
454 struct ext2_reserve_window_node *rsv;
455 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
456
457 if (!block_i)
458 return;
459
460 rsv = &block_i->rsv_window_node;
461 if (!rsv_is_empty(&rsv->rsv_window)) {
462 spin_lock(rsv_lock);
463 if (!rsv_is_empty(&rsv->rsv_window))
464 rsv_window_remove(inode->i_sb, rsv);
465 spin_unlock(rsv_lock);
466 }
467}
468
469/**
470 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks
471 * @inode: inode
472 * @block: start physical block to free
473 * @count: number of blocks to free
474 */
475void ext2_free_blocks(struct inode * inode, ext2_fsblk_t block,
476 unsigned long count)
477{
478 struct buffer_head *bitmap_bh = NULL;
479 struct buffer_head * bh2;
480 unsigned long block_group;
481 unsigned long bit;
482 unsigned long i;
483 unsigned long overflow;
484 struct super_block * sb = inode->i_sb;
485 struct ext2_sb_info * sbi = EXT2_SB(sb);
486 struct ext2_group_desc * desc;
487 struct ext2_super_block * es = sbi->s_es;
488 unsigned freed = 0, group_freed;
489
490 if (!ext2_data_block_valid(sbi, block, count)) {
491 ext2_error (sb, "ext2_free_blocks",
492 "Freeing blocks not in datazone - "
493 "block = %lu, count = %lu", block, count);
494 goto error_return;
495 }
496
497 ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
498
499do_more:
500 overflow = 0;
501 block_group = (block - le32_to_cpu(es->s_first_data_block)) /
502 EXT2_BLOCKS_PER_GROUP(sb);
503 bit = (block - le32_to_cpu(es->s_first_data_block)) %
504 EXT2_BLOCKS_PER_GROUP(sb);
505 /*
506 * Check to see if we are freeing blocks across a group
507 * boundary.
508 */
509 if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
510 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
511 count -= overflow;
512 }
513 brelse(bitmap_bh);
514 bitmap_bh = read_block_bitmap(sb, block_group);
515 if (!bitmap_bh)
516 goto error_return;
517
518 desc = ext2_get_group_desc (sb, block_group, &bh2);
519 if (!desc)
520 goto error_return;
521
522 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
523 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
524 in_range (block, le32_to_cpu(desc->bg_inode_table),
525 sbi->s_itb_per_group) ||
526 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
527 sbi->s_itb_per_group)) {
528 ext2_error (sb, "ext2_free_blocks",
529 "Freeing blocks in system zones - "
530 "Block = %lu, count = %lu",
531 block, count);
532 goto error_return;
533 }
534
535 for (i = 0, group_freed = 0; i < count; i++) {
536 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
537 bit + i, bitmap_bh->b_data)) {
538 ext2_error(sb, __func__,
539 "bit already cleared for block %lu", block + i);
540 } else {
541 group_freed++;
542 }
543 }
544
545 mark_buffer_dirty(bitmap_bh);
546 if (sb->s_flags & SB_SYNCHRONOUS)
547 sync_dirty_buffer(bitmap_bh);
548
549 group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
550 freed += group_freed;
551
552 if (overflow) {
553 block += count;
554 count = overflow;
555 goto do_more;
556 }
557error_return:
558 brelse(bitmap_bh);
559 if (freed) {
560 percpu_counter_add(&sbi->s_freeblocks_counter, freed);
561 dquot_free_block_nodirty(inode, freed);
562 mark_inode_dirty(inode);
563 }
564}
565
566/**
567 * bitmap_search_next_usable_block()
568 * @start: the starting block (group relative) of the search
569 * @bh: bufferhead contains the block group bitmap
570 * @maxblocks: the ending block (group relative) of the reservation
571 *
572 * The bitmap search --- search forward through the actual bitmap on disk until
573 * we find a bit free.
574 */
575static ext2_grpblk_t
576bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
577 ext2_grpblk_t maxblocks)
578{
579 ext2_grpblk_t next;
580
581 next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
582 if (next >= maxblocks)
583 return -1;
584 return next;
585}
586
587/**
588 * find_next_usable_block()
589 * @start: the starting block (group relative) to find next
590 * allocatable block in bitmap.
591 * @bh: bufferhead contains the block group bitmap
592 * @maxblocks: the ending block (group relative) for the search
593 *
594 * Find an allocatable block in a bitmap. We perform the "most
595 * appropriate allocation" algorithm of looking for a free block near
596 * the initial goal; then for a free byte somewhere in the bitmap;
597 * then for any free bit in the bitmap.
598 */
599static ext2_grpblk_t
600find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
601{
602 ext2_grpblk_t here, next;
603 char *p, *r;
604
605 if (start > 0) {
606 /*
607 * The goal was occupied; search forward for a free
608 * block within the next XX blocks.
609 *
610 * end_goal is more or less random, but it has to be
611 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
612 * next 64-bit boundary is simple..
613 */
614 ext2_grpblk_t end_goal = (start + 63) & ~63;
615 if (end_goal > maxblocks)
616 end_goal = maxblocks;
617 here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
618 if (here < end_goal)
619 return here;
620 ext2_debug("Bit not found near goal\n");
621 }
622
623 here = start;
624 if (here < 0)
625 here = 0;
626
627 p = ((char *)bh->b_data) + (here >> 3);
628 r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
629 next = (r - ((char *)bh->b_data)) << 3;
630
631 if (next < maxblocks && next >= here)
632 return next;
633
634 here = bitmap_search_next_usable_block(here, bh, maxblocks);
635 return here;
636}
637
638/**
639 * ext2_try_to_allocate()
640 * @sb: superblock
641 * @group: given allocation block group
642 * @bitmap_bh: bufferhead holds the block bitmap
643 * @grp_goal: given target block within the group
644 * @count: target number of blocks to allocate
645 * @my_rsv: reservation window
646 *
647 * Attempt to allocate blocks within a give range. Set the range of allocation
648 * first, then find the first free bit(s) from the bitmap (within the range),
649 * and at last, allocate the blocks by claiming the found free bit as allocated.
650 *
651 * To set the range of this allocation:
652 * if there is a reservation window, only try to allocate block(s)
653 * from the file's own reservation window;
654 * Otherwise, the allocation range starts from the give goal block,
655 * ends at the block group's last block.
656 *
657 * If we failed to allocate the desired block then we may end up crossing to a
658 * new bitmap.
659 */
660static int
661ext2_try_to_allocate(struct super_block *sb, int group,
662 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
663 unsigned long *count,
664 struct ext2_reserve_window *my_rsv)
665{
666 ext2_fsblk_t group_first_block = ext2_group_first_block_no(sb, group);
667 ext2_fsblk_t group_last_block = ext2_group_last_block_no(sb, group);
668 ext2_grpblk_t start, end;
669 unsigned long num = 0;
670
671 start = 0;
672 end = group_last_block - group_first_block + 1;
673 /* we do allocation within the reservation window if we have a window */
674 if (my_rsv) {
675 if (my_rsv->_rsv_start >= group_first_block)
676 start = my_rsv->_rsv_start - group_first_block;
677 if (my_rsv->_rsv_end < group_last_block)
678 end = my_rsv->_rsv_end - group_first_block + 1;
679 if (grp_goal < start || grp_goal >= end)
680 grp_goal = -1;
681 }
682 BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
683
684 if (grp_goal < 0) {
685 grp_goal = find_next_usable_block(start, bitmap_bh, end);
686 if (grp_goal < 0)
687 goto fail_access;
688 if (!my_rsv) {
689 int i;
690
691 for (i = 0; i < 7 && grp_goal > start &&
692 !ext2_test_bit(grp_goal - 1,
693 bitmap_bh->b_data);
694 i++, grp_goal--)
695 ;
696 }
697 }
698
699 for (; num < *count && grp_goal < end; grp_goal++) {
700 if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
701 grp_goal, bitmap_bh->b_data)) {
702 if (num == 0)
703 continue;
704 break;
705 }
706 num++;
707 }
708
709 if (num == 0)
710 goto fail_access;
711
712 *count = num;
713 return grp_goal - num;
714fail_access:
715 return -1;
716}
717
718/**
719 * find_next_reservable_window - Find a reservable space within the given range.
720 * @search_head: The list to search.
721 * @my_rsv: The reservation we're currently using.
722 * @sb: The super block.
723 * @start_block: The first block we consider to start the real search from
724 * @last_block: The maximum block number that our goal reservable space
725 * could start from.
726 *
727 * It does not allocate the reservation window: alloc_new_reservation()
728 * will do the work later.
729 *
730 * We search the given range, rather than the whole reservation double
731 * linked list, (start_block, last_block) to find a free region that is
732 * of my size and has not been reserved.
733 *
734 * @search_head is not necessarily the list head of the whole filesystem.
735 * We have both head and @start_block to assist the search for the
736 * reservable space. The list starts from head, but we will shift to
737 * the place where start_block is, then start from there, when looking
738 * for a reservable space.
739 *
740 * @last_block is normally the last block in this group. The search will end
741 * when we found the start of next possible reservable space is out
742 * of this boundary. This could handle the cross boundary reservation
743 * window request.
744 *
745 * Return: -1 if we could not find a range of sufficient size. If we could,
746 * return 0 and fill in @my_rsv with the range information.
747 */
748static int find_next_reservable_window(
749 struct ext2_reserve_window_node *search_head,
750 struct ext2_reserve_window_node *my_rsv,
751 struct super_block * sb,
752 ext2_fsblk_t start_block,
753 ext2_fsblk_t last_block)
754{
755 struct rb_node *next;
756 struct ext2_reserve_window_node *rsv, *prev;
757 ext2_fsblk_t cur;
758 int size = my_rsv->rsv_goal_size;
759
760 /* TODO: make the start of the reservation window byte-aligned */
761 /* cur = *start_block & ~7;*/
762 cur = start_block;
763 rsv = search_head;
764 if (!rsv)
765 return -1;
766
767 while (1) {
768 if (cur <= rsv->rsv_end)
769 cur = rsv->rsv_end + 1;
770
771 /* TODO?
772 * in the case we could not find a reservable space
773 * that is what is expected, during the re-search, we could
774 * remember what's the largest reservable space we could have
775 * and return that one.
776 *
777 * For now it will fail if we could not find the reservable
778 * space with expected-size (or more)...
779 */
780 if (cur > last_block)
781 return -1; /* fail */
782
783 prev = rsv;
784 next = rb_next(&rsv->rsv_node);
785 rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
786
787 /*
788 * Reached the last reservation, we can just append to the
789 * previous one.
790 */
791 if (!next)
792 break;
793
794 if (cur + size <= rsv->rsv_start) {
795 /*
796 * Found a reserveable space big enough. We could
797 * have a reservation across the group boundary here
798 */
799 break;
800 }
801 }
802 /*
803 * we come here either :
804 * when we reach the end of the whole list,
805 * and there is empty reservable space after last entry in the list.
806 * append it to the end of the list.
807 *
808 * or we found one reservable space in the middle of the list,
809 * return the reservation window that we could append to.
810 * succeed.
811 */
812
813 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
814 rsv_window_remove(sb, my_rsv);
815
816 /*
817 * Let's book the whole available window for now. We will check the
818 * disk bitmap later and then, if there are free blocks then we adjust
819 * the window size if it's larger than requested.
820 * Otherwise, we will remove this node from the tree next time
821 * call find_next_reservable_window.
822 */
823 my_rsv->rsv_start = cur;
824 my_rsv->rsv_end = cur + size - 1;
825 my_rsv->rsv_alloc_hit = 0;
826
827 if (prev != my_rsv)
828 ext2_rsv_window_add(sb, my_rsv);
829
830 return 0;
831}
832
833/**
834 * alloc_new_reservation - Allocate a new reservation window.
835 * @my_rsv: The reservation we're currently using.
836 * @grp_goal: The goal block relative to the start of the group.
837 * @sb: The super block.
838 * @group: The group we are trying to allocate in.
839 * @bitmap_bh: The block group block bitmap.
840 *
841 * To make a new reservation, we search part of the filesystem reservation
842 * list (the list inside the group). We try to allocate a new
843 * reservation window near @grp_goal, or the beginning of the
844 * group, if @grp_goal is negative.
845 *
846 * We first find a reservable space after the goal, then from there,
847 * we check the bitmap for the first free block after it. If there is
848 * no free block until the end of group, then the whole group is full,
849 * we failed. Otherwise, check if the free block is inside the expected
850 * reservable space, if so, we succeed.
851 *
852 * If the first free block is outside the reservable space, then start
853 * from the first free block, we search for next available space, and
854 * go on.
855 *
856 * on succeed, a new reservation will be found and inserted into the
857 * list. It contains at least one free block, and it does not overlap
858 * with other reservation windows.
859 *
860 * Return: 0 on success, -1 if we failed to find a reservation window
861 * in this group
862 */
863static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
864 ext2_grpblk_t grp_goal, struct super_block *sb,
865 unsigned int group, struct buffer_head *bitmap_bh)
866{
867 struct ext2_reserve_window_node *search_head;
868 ext2_fsblk_t group_first_block, group_end_block, start_block;
869 ext2_grpblk_t first_free_block;
870 struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
871 unsigned long size;
872 int ret;
873 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
874
875 group_first_block = ext2_group_first_block_no(sb, group);
876 group_end_block = ext2_group_last_block_no(sb, group);
877
878 if (grp_goal < 0)
879 start_block = group_first_block;
880 else
881 start_block = grp_goal + group_first_block;
882
883 size = my_rsv->rsv_goal_size;
884
885 if (!rsv_is_empty(&my_rsv->rsv_window)) {
886 /*
887 * if the old reservation is cross group boundary
888 * and if the goal is inside the old reservation window,
889 * we will come here when we just failed to allocate from
890 * the first part of the window. We still have another part
891 * that belongs to the next group. In this case, there is no
892 * point to discard our window and try to allocate a new one
893 * in this group(which will fail). we should
894 * keep the reservation window, just simply move on.
895 *
896 * Maybe we could shift the start block of the reservation
897 * window to the first block of next group.
898 */
899
900 if ((my_rsv->rsv_start <= group_end_block) &&
901 (my_rsv->rsv_end > group_end_block) &&
902 (start_block >= my_rsv->rsv_start))
903 return -1;
904
905 if ((my_rsv->rsv_alloc_hit >
906 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
907 /*
908 * if the previously allocation hit ratio is
909 * greater than 1/2, then we double the size of
910 * the reservation window the next time,
911 * otherwise we keep the same size window
912 */
913 size = size * 2;
914 if (size > EXT2_MAX_RESERVE_BLOCKS)
915 size = EXT2_MAX_RESERVE_BLOCKS;
916 my_rsv->rsv_goal_size= size;
917 }
918 }
919
920 spin_lock(rsv_lock);
921 /*
922 * shift the search start to the window near the goal block
923 */
924 search_head = search_reserve_window(fs_rsv_root, start_block);
925
926 /*
927 * find_next_reservable_window() simply finds a reservable window
928 * inside the given range(start_block, group_end_block).
929 *
930 * To make sure the reservation window has a free bit inside it, we
931 * need to check the bitmap after we found a reservable window.
932 */
933retry:
934 ret = find_next_reservable_window(search_head, my_rsv, sb,
935 start_block, group_end_block);
936
937 if (ret == -1) {
938 if (!rsv_is_empty(&my_rsv->rsv_window))
939 rsv_window_remove(sb, my_rsv);
940 spin_unlock(rsv_lock);
941 return -1;
942 }
943
944 /*
945 * On success, find_next_reservable_window() returns the
946 * reservation window where there is a reservable space after it.
947 * Before we reserve this reservable space, we need
948 * to make sure there is at least a free block inside this region.
949 *
950 * Search the first free bit on the block bitmap. Search starts from
951 * the start block of the reservable space we just found.
952 */
953 spin_unlock(rsv_lock);
954 first_free_block = bitmap_search_next_usable_block(
955 my_rsv->rsv_start - group_first_block,
956 bitmap_bh, group_end_block - group_first_block + 1);
957
958 if (first_free_block < 0) {
959 /*
960 * no free block left on the bitmap, no point
961 * to reserve the space. return failed.
962 */
963 spin_lock(rsv_lock);
964 if (!rsv_is_empty(&my_rsv->rsv_window))
965 rsv_window_remove(sb, my_rsv);
966 spin_unlock(rsv_lock);
967 return -1; /* failed */
968 }
969
970 start_block = first_free_block + group_first_block;
971 /*
972 * check if the first free block is within the
973 * free space we just reserved
974 */
975 if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
976 return 0; /* success */
977 /*
978 * if the first free bit we found is out of the reservable space
979 * continue search for next reservable space,
980 * start from where the free block is,
981 * we also shift the list head to where we stopped last time
982 */
983 search_head = my_rsv;
984 spin_lock(rsv_lock);
985 goto retry;
986}
987
988/**
989 * try_to_extend_reservation()
990 * @my_rsv: given reservation window
991 * @sb: super block
992 * @size: the delta to extend
993 *
994 * Attempt to expand the reservation window large enough to have
995 * required number of free blocks
996 *
997 * Since ext2_try_to_allocate() will always allocate blocks within
998 * the reservation window range, if the window size is too small,
999 * multiple blocks allocation has to stop at the end of the reservation
1000 * window. To make this more efficient, given the total number of
1001 * blocks needed and the current size of the window, we try to
1002 * expand the reservation window size if necessary on a best-effort
1003 * basis before ext2_new_blocks() tries to allocate blocks.
1004 */
1005static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1006 struct super_block *sb, int size)
1007{
1008 struct ext2_reserve_window_node *next_rsv;
1009 struct rb_node *next;
1010 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1011
1012 if (!spin_trylock(rsv_lock))
1013 return;
1014
1015 next = rb_next(&my_rsv->rsv_node);
1016
1017 if (!next)
1018 my_rsv->rsv_end += size;
1019 else {
1020 next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1021
1022 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1023 my_rsv->rsv_end += size;
1024 else
1025 my_rsv->rsv_end = next_rsv->rsv_start - 1;
1026 }
1027 spin_unlock(rsv_lock);
1028}
1029
1030/**
1031 * ext2_try_to_allocate_with_rsv()
1032 * @sb: superblock
1033 * @group: given allocation block group
1034 * @bitmap_bh: bufferhead holds the block bitmap
1035 * @grp_goal: given target block within the group
1036 * @count: target number of blocks to allocate
1037 * @my_rsv: reservation window
1038 *
1039 * This is the main function used to allocate a new block and its reservation
1040 * window.
1041 *
1042 * Each time when a new block allocation is need, first try to allocate from
1043 * its own reservation. If it does not have a reservation window, instead of
1044 * looking for a free bit on bitmap first, then look up the reservation list to
1045 * see if it is inside somebody else's reservation window, we try to allocate a
1046 * reservation window for it starting from the goal first. Then do the block
1047 * allocation within the reservation window.
1048 *
1049 * This will avoid keeping on searching the reservation list again and
1050 * again when somebody is looking for a free block (without
1051 * reservation), and there are lots of free blocks, but they are all
1052 * being reserved.
1053 *
1054 * We use a red-black tree for the per-filesystem reservation list.
1055 */
1056static ext2_grpblk_t
1057ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1058 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1059 struct ext2_reserve_window_node * my_rsv,
1060 unsigned long *count)
1061{
1062 ext2_fsblk_t group_first_block, group_last_block;
1063 ext2_grpblk_t ret = 0;
1064 unsigned long num = *count;
1065
1066 /*
1067 * we don't deal with reservation when
1068 * filesystem is mounted without reservation
1069 * or the file is not a regular file
1070 * or last attempt to allocate a block with reservation turned on failed
1071 */
1072 if (my_rsv == NULL) {
1073 return ext2_try_to_allocate(sb, group, bitmap_bh,
1074 grp_goal, count, NULL);
1075 }
1076 /*
1077 * grp_goal is a group relative block number (if there is a goal)
1078 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1079 * first block is a filesystem wide block number
1080 * first block is the block number of the first block in this group
1081 */
1082 group_first_block = ext2_group_first_block_no(sb, group);
1083 group_last_block = ext2_group_last_block_no(sb, group);
1084
1085 /*
1086 * Basically we will allocate a new block from inode's reservation
1087 * window.
1088 *
1089 * We need to allocate a new reservation window, if:
1090 * a) inode does not have a reservation window; or
1091 * b) last attempt to allocate a block from existing reservation
1092 * failed; or
1093 * c) we come here with a goal and with a reservation window
1094 *
1095 * We do not need to allocate a new reservation window if we come here
1096 * at the beginning with a goal and the goal is inside the window, or
1097 * we don't have a goal but already have a reservation window.
1098 * then we could go to allocate from the reservation window directly.
1099 */
1100 while (1) {
1101 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1102 !goal_in_my_reservation(&my_rsv->rsv_window,
1103 grp_goal, group, sb)) {
1104 if (my_rsv->rsv_goal_size < *count)
1105 my_rsv->rsv_goal_size = *count;
1106 ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1107 group, bitmap_bh);
1108 if (ret < 0)
1109 break; /* failed */
1110
1111 if (!goal_in_my_reservation(&my_rsv->rsv_window,
1112 grp_goal, group, sb))
1113 grp_goal = -1;
1114 } else if (grp_goal >= 0) {
1115 int curr = my_rsv->rsv_end -
1116 (grp_goal + group_first_block) + 1;
1117
1118 if (curr < *count)
1119 try_to_extend_reservation(my_rsv, sb,
1120 *count - curr);
1121 }
1122
1123 if ((my_rsv->rsv_start > group_last_block) ||
1124 (my_rsv->rsv_end < group_first_block)) {
1125 ext2_error(sb, __func__,
1126 "Reservation out of group %u range goal %d fsb[%lu,%lu] rsv[%lu, %lu]",
1127 group, grp_goal, group_first_block,
1128 group_last_block, my_rsv->rsv_start,
1129 my_rsv->rsv_end);
1130 rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1131 return -1;
1132 }
1133 ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1134 &num, &my_rsv->rsv_window);
1135 if (ret >= 0) {
1136 my_rsv->rsv_alloc_hit += num;
1137 *count = num;
1138 break; /* succeed */
1139 }
1140 num = *count;
1141 }
1142 return ret;
1143}
1144
1145/**
1146 * ext2_has_free_blocks()
1147 * @sbi: in-core super block structure.
1148 *
1149 * Check if filesystem has at least 1 free block available for allocation.
1150 */
1151static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1152{
1153 ext2_fsblk_t free_blocks, root_blocks;
1154
1155 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1156 root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1157 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1158 !uid_eq(sbi->s_resuid, current_fsuid()) &&
1159 (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1160 !in_group_p (sbi->s_resgid))) {
1161 return 0;
1162 }
1163 return 1;
1164}
1165
1166/*
1167 * Returns 1 if the passed-in block region is valid; 0 if some part overlaps
1168 * with filesystem metadata blocks.
1169 */
1170int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
1171 unsigned int count)
1172{
1173 if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
1174 (start_blk + count - 1 < start_blk) ||
1175 (start_blk + count - 1 >= le32_to_cpu(sbi->s_es->s_blocks_count)))
1176 return 0;
1177
1178 /* Ensure we do not step over superblock */
1179 if ((start_blk <= sbi->s_sb_block) &&
1180 (start_blk + count - 1 >= sbi->s_sb_block))
1181 return 0;
1182
1183 return 1;
1184}
1185
1186/*
1187 * ext2_new_blocks() -- core block(s) allocation function
1188 * @inode: file inode
1189 * @goal: given target block(filesystem wide)
1190 * @count: target number of blocks to allocate
1191 * @errp: error code
1192 * @flags: allocate flags
1193 *
1194 * ext2_new_blocks uses a goal block to assist allocation. If the goal is
1195 * free, or there is a free block within 32 blocks of the goal, that block
1196 * is allocated. Otherwise a forward search is made for a free block; within
1197 * each block group the search first looks for an entire free byte in the block
1198 * bitmap, and then for any free bit if that fails.
1199 * This function also updates quota and i_blocks field.
1200 */
1201ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1202 unsigned long *count, int *errp, unsigned int flags)
1203{
1204 struct buffer_head *bitmap_bh = NULL;
1205 struct buffer_head *gdp_bh;
1206 int group_no;
1207 int goal_group;
1208 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1209 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1210 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1211 int bgi; /* blockgroup iteration index */
1212 int performed_allocation = 0;
1213 ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1214 struct super_block *sb;
1215 struct ext2_group_desc *gdp;
1216 struct ext2_super_block *es;
1217 struct ext2_sb_info *sbi;
1218 struct ext2_reserve_window_node *my_rsv = NULL;
1219 struct ext2_block_alloc_info *block_i;
1220 unsigned short windowsz = 0;
1221 unsigned long ngroups;
1222 unsigned long num = *count;
1223 int ret;
1224
1225 *errp = -ENOSPC;
1226 sb = inode->i_sb;
1227
1228 /*
1229 * Check quota for allocation of this block.
1230 */
1231 ret = dquot_alloc_block(inode, num);
1232 if (ret) {
1233 *errp = ret;
1234 return 0;
1235 }
1236
1237 sbi = EXT2_SB(sb);
1238 es = EXT2_SB(sb)->s_es;
1239 ext2_debug("goal=%lu.\n", goal);
1240 /*
1241 * Allocate a block from reservation only when the filesystem is
1242 * mounted with reservation(default,-o reservation), and it's a regular
1243 * file, and the desired window size is greater than 0 (One could use
1244 * ioctl command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn
1245 * off reservation on that particular file). Also do not use the
1246 * reservation window if the caller asked us not to do it.
1247 */
1248 block_i = EXT2_I(inode)->i_block_alloc_info;
1249 if (!(flags & EXT2_ALLOC_NORESERVE) && block_i) {
1250 windowsz = block_i->rsv_window_node.rsv_goal_size;
1251 if (windowsz > 0)
1252 my_rsv = &block_i->rsv_window_node;
1253 }
1254
1255 if (!ext2_has_free_blocks(sbi)) {
1256 *errp = -ENOSPC;
1257 goto out;
1258 }
1259
1260 /*
1261 * First, test whether the goal block is free.
1262 */
1263 if (goal < le32_to_cpu(es->s_first_data_block) ||
1264 goal >= le32_to_cpu(es->s_blocks_count))
1265 goal = le32_to_cpu(es->s_first_data_block);
1266 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1267 EXT2_BLOCKS_PER_GROUP(sb);
1268 goal_group = group_no;
1269retry_alloc:
1270 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1271 if (!gdp)
1272 goto io_error;
1273
1274 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1275 /*
1276 * if there is not enough free blocks to make a new resevation
1277 * turn off reservation for this allocation
1278 */
1279 if (my_rsv && (free_blocks < windowsz)
1280 && (free_blocks > 0)
1281 && (rsv_is_empty(&my_rsv->rsv_window)))
1282 my_rsv = NULL;
1283
1284 if (free_blocks > 0) {
1285 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1286 EXT2_BLOCKS_PER_GROUP(sb));
1287 /*
1288 * In case we retry allocation (due to fs reservation not
1289 * working out or fs corruption), the bitmap_bh is non-null
1290 * pointer and we have to release it before calling
1291 * read_block_bitmap().
1292 */
1293 brelse(bitmap_bh);
1294 bitmap_bh = read_block_bitmap(sb, group_no);
1295 if (!bitmap_bh)
1296 goto io_error;
1297 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1298 bitmap_bh, grp_target_blk,
1299 my_rsv, &num);
1300 if (grp_alloc_blk >= 0)
1301 goto allocated;
1302 }
1303
1304 ngroups = EXT2_SB(sb)->s_groups_count;
1305 smp_rmb();
1306
1307 /*
1308 * Now search the rest of the groups. We assume that
1309 * group_no and gdp correctly point to the last group visited.
1310 */
1311 for (bgi = 0; bgi < ngroups; bgi++) {
1312 group_no++;
1313 if (group_no >= ngroups)
1314 group_no = 0;
1315 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1316 if (!gdp)
1317 goto io_error;
1318
1319 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1320 /*
1321 * skip this group (and avoid loading bitmap) if there
1322 * are no free blocks
1323 */
1324 if (!free_blocks)
1325 continue;
1326 /*
1327 * skip this group if the number of
1328 * free blocks is less than half of the reservation
1329 * window size.
1330 */
1331 if (my_rsv && (free_blocks <= (windowsz/2)))
1332 continue;
1333
1334 brelse(bitmap_bh);
1335 bitmap_bh = read_block_bitmap(sb, group_no);
1336 if (!bitmap_bh)
1337 goto io_error;
1338 /*
1339 * try to allocate block(s) from this group, without a goal(-1).
1340 */
1341 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1342 bitmap_bh, -1, my_rsv, &num);
1343 if (grp_alloc_blk >= 0)
1344 goto allocated;
1345 }
1346 /*
1347 * We may end up a bogus earlier ENOSPC error due to
1348 * filesystem is "full" of reservations, but
1349 * there maybe indeed free blocks available on disk
1350 * In this case, we just forget about the reservations
1351 * just do block allocation as without reservations.
1352 */
1353 if (my_rsv) {
1354 my_rsv = NULL;
1355 windowsz = 0;
1356 group_no = goal_group;
1357 goto retry_alloc;
1358 }
1359 /* No space left on the device */
1360 *errp = -ENOSPC;
1361 goto out;
1362
1363allocated:
1364
1365 ext2_debug("using block group %d(%d)\n",
1366 group_no, gdp->bg_free_blocks_count);
1367
1368 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1369
1370 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1371 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1372 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1373 EXT2_SB(sb)->s_itb_per_group) ||
1374 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1375 EXT2_SB(sb)->s_itb_per_group)) {
1376 ext2_error(sb, "ext2_new_blocks",
1377 "Allocating block in system zone - "
1378 "blocks from "E2FSBLK", length %lu",
1379 ret_block, num);
1380 /*
1381 * ext2_try_to_allocate marked the blocks we allocated as in
1382 * use. So we may want to selectively mark some of the blocks
1383 * as free
1384 */
1385 num = *count;
1386 goto retry_alloc;
1387 }
1388
1389 performed_allocation = 1;
1390
1391 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1392 ext2_error(sb, "ext2_new_blocks",
1393 "block("E2FSBLK") >= blocks count(%d) - "
1394 "block_group = %d, es == %p ", ret_block,
1395 le32_to_cpu(es->s_blocks_count), group_no, es);
1396 goto out;
1397 }
1398
1399 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1400 percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1401
1402 mark_buffer_dirty(bitmap_bh);
1403 if (sb->s_flags & SB_SYNCHRONOUS)
1404 sync_dirty_buffer(bitmap_bh);
1405
1406 *errp = 0;
1407 brelse(bitmap_bh);
1408 if (num < *count) {
1409 dquot_free_block_nodirty(inode, *count-num);
1410 mark_inode_dirty(inode);
1411 *count = num;
1412 }
1413 return ret_block;
1414
1415io_error:
1416 *errp = -EIO;
1417out:
1418 /*
1419 * Undo the block allocation
1420 */
1421 if (!performed_allocation) {
1422 dquot_free_block_nodirty(inode, *count);
1423 mark_inode_dirty(inode);
1424 }
1425 brelse(bitmap_bh);
1426 return 0;
1427}
1428
1429#ifdef EXT2FS_DEBUG
1430
1431unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
1432{
1433 return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
1434}
1435
1436#endif /* EXT2FS_DEBUG */
1437
1438unsigned long ext2_count_free_blocks (struct super_block * sb)
1439{
1440 struct ext2_group_desc * desc;
1441 unsigned long desc_count = 0;
1442 int i;
1443#ifdef EXT2FS_DEBUG
1444 unsigned long bitmap_count, x;
1445 struct ext2_super_block *es;
1446
1447 es = EXT2_SB(sb)->s_es;
1448 desc_count = 0;
1449 bitmap_count = 0;
1450 desc = NULL;
1451 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1452 struct buffer_head *bitmap_bh;
1453 desc = ext2_get_group_desc (sb, i, NULL);
1454 if (!desc)
1455 continue;
1456 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1457 bitmap_bh = read_block_bitmap(sb, i);
1458 if (!bitmap_bh)
1459 continue;
1460
1461 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1462 printk ("group %d: stored = %d, counted = %lu\n",
1463 i, le16_to_cpu(desc->bg_free_blocks_count), x);
1464 bitmap_count += x;
1465 brelse(bitmap_bh);
1466 }
1467 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1468 (long)le32_to_cpu(es->s_free_blocks_count),
1469 desc_count, bitmap_count);
1470 return bitmap_count;
1471#else
1472 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1473 desc = ext2_get_group_desc(sb, i, NULL);
1474 if (!desc)
1475 continue;
1476 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1477 }
1478 return desc_count;
1479#endif
1480}
1481
1482static inline int test_root(int a, int b)
1483{
1484 int num = b;
1485
1486 while (a > num)
1487 num *= b;
1488 return num == a;
1489}
1490
1491static int ext2_group_sparse(int group)
1492{
1493 if (group <= 1)
1494 return 1;
1495 return (test_root(group, 3) || test_root(group, 5) ||
1496 test_root(group, 7));
1497}
1498
1499/**
1500 * ext2_bg_has_super - number of blocks used by the superblock in group
1501 * @sb: superblock for filesystem
1502 * @group: group number to check
1503 *
1504 * Return the number of blocks used by the superblock (primary or backup)
1505 * in this group. Currently this will be only 0 or 1.
1506 */
1507int ext2_bg_has_super(struct super_block *sb, int group)
1508{
1509 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1510 !ext2_group_sparse(group))
1511 return 0;
1512 return 1;
1513}
1514
1515/**
1516 * ext2_bg_num_gdb - number of blocks used by the group table in group
1517 * @sb: superblock for filesystem
1518 * @group: group number to check
1519 *
1520 * Return the number of blocks used by the group descriptor table
1521 * (primary or backup) in this group. In the future there may be a
1522 * different number of descriptor blocks in each group.
1523 */
1524unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1525{
1526 return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1527}
1528
1/*
2 * linux/fs/ext2/balloc.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 *
9 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10 * Big-endian to little-endian byte-swapping/bitmaps by
11 * David S. Miller (davem@caip.rutgers.edu), 1995
12 */
13
14#include "ext2.h"
15#include <linux/quotaops.h>
16#include <linux/slab.h>
17#include <linux/sched.h>
18#include <linux/buffer_head.h>
19#include <linux/capability.h>
20
21/*
22 * balloc.c contains the blocks allocation and deallocation routines
23 */
24
25/*
26 * The free blocks are managed by bitmaps. A file system contains several
27 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
28 * block for inodes, N blocks for the inode table and data blocks.
29 *
30 * The file system contains group descriptors which are located after the
31 * super block. Each descriptor contains the number of the bitmap block and
32 * the free blocks count in the block. The descriptors are loaded in memory
33 * when a file system is mounted (see ext2_fill_super).
34 */
35
36
37#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
38
39struct 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 ext2_error (sb, "ext2_get_group_desc",
50 "block_group >= groups_count - "
51 "block_group = %d, groups_count = %lu",
52 block_group, sbi->s_groups_count);
53
54 return NULL;
55 }
56
57 group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
58 offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
59 if (!sbi->s_group_desc[group_desc]) {
60 ext2_error (sb, "ext2_get_group_desc",
61 "Group descriptor not loaded - "
62 "block_group = %d, group_desc = %lu, desc = %lu",
63 block_group, group_desc, offset);
64 return NULL;
65 }
66
67 desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;
68 if (bh)
69 *bh = sbi->s_group_desc[group_desc];
70 return desc + offset;
71}
72
73static int ext2_valid_block_bitmap(struct super_block *sb,
74 struct ext2_group_desc *desc,
75 unsigned int block_group,
76 struct buffer_head *bh)
77{
78 ext2_grpblk_t offset;
79 ext2_grpblk_t next_zero_bit;
80 ext2_fsblk_t bitmap_blk;
81 ext2_fsblk_t group_first_block;
82
83 group_first_block = ext2_group_first_block_no(sb, block_group);
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 (!ext2_test_bit(offset, bh->b_data))
89 /* bad block bitmap */
90 goto err_out;
91
92 /* check whether the inode bitmap block number is set */
93 bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
94 offset = bitmap_blk - group_first_block;
95 if (!ext2_test_bit(offset, bh->b_data))
96 /* bad block bitmap */
97 goto err_out;
98
99 /* check whether the inode table block number is set */
100 bitmap_blk = le32_to_cpu(desc->bg_inode_table);
101 offset = bitmap_blk - group_first_block;
102 next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
103 offset + EXT2_SB(sb)->s_itb_per_group,
104 offset);
105 if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
106 /* good bitmap for inode tables */
107 return 1;
108
109err_out:
110 ext2_error(sb, __func__,
111 "Invalid block bitmap - "
112 "block_group = %d, block = %lu",
113 block_group, bitmap_blk);
114 return 0;
115}
116
117/*
118 * Read the bitmap for a given block_group,and validate the
119 * bits for block/inode/inode tables are set in the bitmaps
120 *
121 * Return buffer_head on success or NULL in case of failure.
122 */
123static struct buffer_head *
124read_block_bitmap(struct super_block *sb, unsigned int block_group)
125{
126 struct ext2_group_desc * desc;
127 struct buffer_head * bh = NULL;
128 ext2_fsblk_t bitmap_blk;
129
130 desc = ext2_get_group_desc(sb, block_group, NULL);
131 if (!desc)
132 return NULL;
133 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
134 bh = sb_getblk(sb, bitmap_blk);
135 if (unlikely(!bh)) {
136 ext2_error(sb, __func__,
137 "Cannot read block bitmap - "
138 "block_group = %d, block_bitmap = %u",
139 block_group, le32_to_cpu(desc->bg_block_bitmap));
140 return NULL;
141 }
142 if (likely(bh_uptodate_or_lock(bh)))
143 return bh;
144
145 if (bh_submit_read(bh) < 0) {
146 brelse(bh);
147 ext2_error(sb, __func__,
148 "Cannot read block bitmap - "
149 "block_group = %d, block_bitmap = %u",
150 block_group, le32_to_cpu(desc->bg_block_bitmap));
151 return NULL;
152 }
153
154 ext2_valid_block_bitmap(sb, desc, block_group, bh);
155 /*
156 * file system mounted not to panic on error, continue with corrupt
157 * bitmap
158 */
159 return bh;
160}
161
162static void group_adjust_blocks(struct super_block *sb, int group_no,
163 struct ext2_group_desc *desc, struct buffer_head *bh, int count)
164{
165 if (count) {
166 struct ext2_sb_info *sbi = EXT2_SB(sb);
167 unsigned free_blocks;
168
169 spin_lock(sb_bgl_lock(sbi, group_no));
170 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
171 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
172 spin_unlock(sb_bgl_lock(sbi, group_no));
173 mark_buffer_dirty(bh);
174 }
175}
176
177/*
178 * The reservation window structure operations
179 * --------------------------------------------
180 * Operations include:
181 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
182 *
183 * We use a red-black tree to represent per-filesystem reservation
184 * windows.
185 *
186 */
187
188/**
189 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
190 * @rb_root: root of per-filesystem reservation rb tree
191 * @verbose: verbose mode
192 * @fn: function which wishes to dump the reservation map
193 *
194 * If verbose is turned on, it will print the whole block reservation
195 * windows(start, end). Otherwise, it will only print out the "bad" windows,
196 * those windows that overlap with their immediate neighbors.
197 */
198#if 1
199static void __rsv_window_dump(struct rb_root *root, int verbose,
200 const char *fn)
201{
202 struct rb_node *n;
203 struct ext2_reserve_window_node *rsv, *prev;
204 int bad;
205
206restart:
207 n = rb_first(root);
208 bad = 0;
209 prev = NULL;
210
211 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
212 while (n) {
213 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
214 if (verbose)
215 printk("reservation window 0x%p "
216 "start: %lu, end: %lu\n",
217 rsv, rsv->rsv_start, rsv->rsv_end);
218 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
219 printk("Bad reservation %p (start >= end)\n",
220 rsv);
221 bad = 1;
222 }
223 if (prev && prev->rsv_end >= rsv->rsv_start) {
224 printk("Bad reservation %p (prev->end >= start)\n",
225 rsv);
226 bad = 1;
227 }
228 if (bad) {
229 if (!verbose) {
230 printk("Restarting reservation walk in verbose mode\n");
231 verbose = 1;
232 goto restart;
233 }
234 }
235 n = rb_next(n);
236 prev = rsv;
237 }
238 printk("Window map complete.\n");
239 BUG_ON(bad);
240}
241#define rsv_window_dump(root, verbose) \
242 __rsv_window_dump((root), (verbose), __func__)
243#else
244#define rsv_window_dump(root, verbose) do {} while (0)
245#endif
246
247/**
248 * goal_in_my_reservation()
249 * @rsv: inode's reservation window
250 * @grp_goal: given goal block relative to the allocation block group
251 * @group: the current allocation block group
252 * @sb: filesystem super block
253 *
254 * Test if the given goal block (group relative) is within the file's
255 * own block reservation window range.
256 *
257 * If the reservation window is outside the goal allocation group, return 0;
258 * grp_goal (given goal block) could be -1, which means no specific
259 * goal block. In this case, always return 1.
260 * If the goal block is within the reservation window, return 1;
261 * otherwise, return 0;
262 */
263static int
264goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
265 unsigned int group, struct super_block * sb)
266{
267 ext2_fsblk_t group_first_block, group_last_block;
268
269 group_first_block = ext2_group_first_block_no(sb, group);
270 group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
271
272 if ((rsv->_rsv_start > group_last_block) ||
273 (rsv->_rsv_end < group_first_block))
274 return 0;
275 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
276 || (grp_goal + group_first_block > rsv->_rsv_end)))
277 return 0;
278 return 1;
279}
280
281/**
282 * search_reserve_window()
283 * @rb_root: root of reservation tree
284 * @goal: target allocation block
285 *
286 * Find the reserved window which includes the goal, or the previous one
287 * if the goal is not in any window.
288 * Returns NULL if there are no windows or if all windows start after the goal.
289 */
290static struct ext2_reserve_window_node *
291search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
292{
293 struct rb_node *n = root->rb_node;
294 struct ext2_reserve_window_node *rsv;
295
296 if (!n)
297 return NULL;
298
299 do {
300 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
301
302 if (goal < rsv->rsv_start)
303 n = n->rb_left;
304 else if (goal > rsv->rsv_end)
305 n = n->rb_right;
306 else
307 return rsv;
308 } while (n);
309 /*
310 * We've fallen off the end of the tree: the goal wasn't inside
311 * any particular node. OK, the previous node must be to one
312 * side of the interval containing the goal. If it's the RHS,
313 * we need to back up one.
314 */
315 if (rsv->rsv_start > goal) {
316 n = rb_prev(&rsv->rsv_node);
317 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
318 }
319 return rsv;
320}
321
322/*
323 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
324 * @sb: super block
325 * @rsv: reservation window to add
326 *
327 * Must be called with rsv_lock held.
328 */
329void ext2_rsv_window_add(struct super_block *sb,
330 struct ext2_reserve_window_node *rsv)
331{
332 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
333 struct rb_node *node = &rsv->rsv_node;
334 ext2_fsblk_t start = rsv->rsv_start;
335
336 struct rb_node ** p = &root->rb_node;
337 struct rb_node * parent = NULL;
338 struct ext2_reserve_window_node *this;
339
340 while (*p)
341 {
342 parent = *p;
343 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
344
345 if (start < this->rsv_start)
346 p = &(*p)->rb_left;
347 else if (start > this->rsv_end)
348 p = &(*p)->rb_right;
349 else {
350 rsv_window_dump(root, 1);
351 BUG();
352 }
353 }
354
355 rb_link_node(node, parent, p);
356 rb_insert_color(node, root);
357}
358
359/**
360 * rsv_window_remove() -- unlink a window from the reservation rb tree
361 * @sb: super block
362 * @rsv: reservation window to remove
363 *
364 * Mark the block reservation window as not allocated, and unlink it
365 * from the filesystem reservation window rb tree. Must be called with
366 * rsv_lock held.
367 */
368static void rsv_window_remove(struct super_block *sb,
369 struct ext2_reserve_window_node *rsv)
370{
371 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
372 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
373 rsv->rsv_alloc_hit = 0;
374 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
375}
376
377/*
378 * rsv_is_empty() -- Check if the reservation window is allocated.
379 * @rsv: given reservation window to check
380 *
381 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
382 */
383static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
384{
385 /* a valid reservation end block could not be 0 */
386 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
387}
388
389/**
390 * ext2_init_block_alloc_info()
391 * @inode: file inode structure
392 *
393 * Allocate and initialize the reservation window structure, and
394 * link the window to the ext2 inode structure at last
395 *
396 * The reservation window structure is only dynamically allocated
397 * and linked to ext2 inode the first time the open file
398 * needs a new block. So, before every ext2_new_block(s) call, for
399 * regular files, we should check whether the reservation window
400 * structure exists or not. In the latter case, this function is called.
401 * Fail to do so will result in block reservation being turned off for that
402 * open file.
403 *
404 * This function is called from ext2_get_blocks_handle(), also called
405 * when setting the reservation window size through ioctl before the file
406 * is open for write (needs block allocation).
407 *
408 * Needs truncate_mutex protection prior to calling this function.
409 */
410void ext2_init_block_alloc_info(struct inode *inode)
411{
412 struct ext2_inode_info *ei = EXT2_I(inode);
413 struct ext2_block_alloc_info *block_i;
414 struct super_block *sb = inode->i_sb;
415
416 block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
417 if (block_i) {
418 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
419
420 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
421 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
422
423 /*
424 * if filesystem is mounted with NORESERVATION, the goal
425 * reservation window size is set to zero to indicate
426 * block reservation is off
427 */
428 if (!test_opt(sb, RESERVATION))
429 rsv->rsv_goal_size = 0;
430 else
431 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
432 rsv->rsv_alloc_hit = 0;
433 block_i->last_alloc_logical_block = 0;
434 block_i->last_alloc_physical_block = 0;
435 }
436 ei->i_block_alloc_info = block_i;
437}
438
439/**
440 * ext2_discard_reservation()
441 * @inode: inode
442 *
443 * Discard(free) block reservation window on last file close, or truncate
444 * or at last iput().
445 *
446 * It is being called in three cases:
447 * ext2_release_file(): last writer closes the file
448 * ext2_clear_inode(): last iput(), when nobody links to this file.
449 * ext2_truncate(): when the block indirect map is about to change.
450 */
451void ext2_discard_reservation(struct inode *inode)
452{
453 struct ext2_inode_info *ei = EXT2_I(inode);
454 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
455 struct ext2_reserve_window_node *rsv;
456 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
457
458 if (!block_i)
459 return;
460
461 rsv = &block_i->rsv_window_node;
462 if (!rsv_is_empty(&rsv->rsv_window)) {
463 spin_lock(rsv_lock);
464 if (!rsv_is_empty(&rsv->rsv_window))
465 rsv_window_remove(inode->i_sb, rsv);
466 spin_unlock(rsv_lock);
467 }
468}
469
470/**
471 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks
472 * @inode: inode
473 * @block: start physical block to free
474 * @count: number of blocks to free
475 */
476void ext2_free_blocks (struct inode * inode, unsigned long block,
477 unsigned long count)
478{
479 struct buffer_head *bitmap_bh = NULL;
480 struct buffer_head * bh2;
481 unsigned long block_group;
482 unsigned long bit;
483 unsigned long i;
484 unsigned long overflow;
485 struct super_block * sb = inode->i_sb;
486 struct ext2_sb_info * sbi = EXT2_SB(sb);
487 struct ext2_group_desc * desc;
488 struct ext2_super_block * es = sbi->s_es;
489 unsigned freed = 0, group_freed;
490
491 if (block < le32_to_cpu(es->s_first_data_block) ||
492 block + count < block ||
493 block + count > le32_to_cpu(es->s_blocks_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
502do_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 & MS_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 }
560error_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 */
578static ext2_grpblk_t
579bitmap_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 */
602static ext2_grpblk_t
603find_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 */
663static int
664ext2_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
699repeat:
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;
738fail_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 */
776static 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 */
898static 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 */
968retry:
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 */
1040static 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 */
1091static ext2_grpblk_t
1092ext2_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 */
1181static 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 * ext2_new_blocks() -- core block(s) allocation function
1198 * @inode: file inode
1199 * @goal: given target block(filesystem wide)
1200 * @count: target number of blocks to allocate
1201 * @errp: error code
1202 *
1203 * ext2_new_blocks uses a goal block to assist allocation. If the goal is
1204 * free, or there is a free block within 32 blocks of the goal, that block
1205 * is allocated. Otherwise a forward search is made for a free block; within
1206 * each block group the search first looks for an entire free byte in the block
1207 * bitmap, and then for any free bit if that fails.
1208 * This function also updates quota and i_blocks field.
1209 */
1210ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1211 unsigned long *count, int *errp)
1212{
1213 struct buffer_head *bitmap_bh = NULL;
1214 struct buffer_head *gdp_bh;
1215 int group_no;
1216 int goal_group;
1217 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1218 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1219 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1220 int bgi; /* blockgroup iteration index */
1221 int performed_allocation = 0;
1222 ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1223 struct super_block *sb;
1224 struct ext2_group_desc *gdp;
1225 struct ext2_super_block *es;
1226 struct ext2_sb_info *sbi;
1227 struct ext2_reserve_window_node *my_rsv = NULL;
1228 struct ext2_block_alloc_info *block_i;
1229 unsigned short windowsz = 0;
1230 unsigned long ngroups;
1231 unsigned long num = *count;
1232 int ret;
1233
1234 *errp = -ENOSPC;
1235 sb = inode->i_sb;
1236
1237 /*
1238 * Check quota for allocation of this block.
1239 */
1240 ret = dquot_alloc_block(inode, num);
1241 if (ret) {
1242 *errp = ret;
1243 return 0;
1244 }
1245
1246 sbi = EXT2_SB(sb);
1247 es = EXT2_SB(sb)->s_es;
1248 ext2_debug("goal=%lu.\n", goal);
1249 /*
1250 * Allocate a block from reservation only when
1251 * filesystem is mounted with reservation(default,-o reservation), and
1252 * it's a regular file, and
1253 * the desired window size is greater than 0 (One could use ioctl
1254 * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1255 * reservation on that particular file)
1256 */
1257 block_i = EXT2_I(inode)->i_block_alloc_info;
1258 if (block_i) {
1259 windowsz = block_i->rsv_window_node.rsv_goal_size;
1260 if (windowsz > 0)
1261 my_rsv = &block_i->rsv_window_node;
1262 }
1263
1264 if (!ext2_has_free_blocks(sbi)) {
1265 *errp = -ENOSPC;
1266 goto out;
1267 }
1268
1269 /*
1270 * First, test whether the goal block is free.
1271 */
1272 if (goal < le32_to_cpu(es->s_first_data_block) ||
1273 goal >= le32_to_cpu(es->s_blocks_count))
1274 goal = le32_to_cpu(es->s_first_data_block);
1275 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1276 EXT2_BLOCKS_PER_GROUP(sb);
1277 goal_group = group_no;
1278retry_alloc:
1279 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1280 if (!gdp)
1281 goto io_error;
1282
1283 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1284 /*
1285 * if there is not enough free blocks to make a new resevation
1286 * turn off reservation for this allocation
1287 */
1288 if (my_rsv && (free_blocks < windowsz)
1289 && (free_blocks > 0)
1290 && (rsv_is_empty(&my_rsv->rsv_window)))
1291 my_rsv = NULL;
1292
1293 if (free_blocks > 0) {
1294 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1295 EXT2_BLOCKS_PER_GROUP(sb));
1296 bitmap_bh = read_block_bitmap(sb, group_no);
1297 if (!bitmap_bh)
1298 goto io_error;
1299 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1300 bitmap_bh, grp_target_blk,
1301 my_rsv, &num);
1302 if (grp_alloc_blk >= 0)
1303 goto allocated;
1304 }
1305
1306 ngroups = EXT2_SB(sb)->s_groups_count;
1307 smp_rmb();
1308
1309 /*
1310 * Now search the rest of the groups. We assume that
1311 * group_no and gdp correctly point to the last group visited.
1312 */
1313 for (bgi = 0; bgi < ngroups; bgi++) {
1314 group_no++;
1315 if (group_no >= ngroups)
1316 group_no = 0;
1317 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1318 if (!gdp)
1319 goto io_error;
1320
1321 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1322 /*
1323 * skip this group (and avoid loading bitmap) if there
1324 * are no free blocks
1325 */
1326 if (!free_blocks)
1327 continue;
1328 /*
1329 * skip this group if the number of
1330 * free blocks is less than half of the reservation
1331 * window size.
1332 */
1333 if (my_rsv && (free_blocks <= (windowsz/2)))
1334 continue;
1335
1336 brelse(bitmap_bh);
1337 bitmap_bh = read_block_bitmap(sb, group_no);
1338 if (!bitmap_bh)
1339 goto io_error;
1340 /*
1341 * try to allocate block(s) from this group, without a goal(-1).
1342 */
1343 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1344 bitmap_bh, -1, my_rsv, &num);
1345 if (grp_alloc_blk >= 0)
1346 goto allocated;
1347 }
1348 /*
1349 * We may end up a bogus earlier ENOSPC error due to
1350 * filesystem is "full" of reservations, but
1351 * there maybe indeed free blocks available on disk
1352 * In this case, we just forget about the reservations
1353 * just do block allocation as without reservations.
1354 */
1355 if (my_rsv) {
1356 my_rsv = NULL;
1357 windowsz = 0;
1358 group_no = goal_group;
1359 goto retry_alloc;
1360 }
1361 /* No space left on the device */
1362 *errp = -ENOSPC;
1363 goto out;
1364
1365allocated:
1366
1367 ext2_debug("using block group %d(%d)\n",
1368 group_no, gdp->bg_free_blocks_count);
1369
1370 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1371
1372 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1373 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1374 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1375 EXT2_SB(sb)->s_itb_per_group) ||
1376 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1377 EXT2_SB(sb)->s_itb_per_group)) {
1378 ext2_error(sb, "ext2_new_blocks",
1379 "Allocating block in system zone - "
1380 "blocks from "E2FSBLK", length %lu",
1381 ret_block, num);
1382 /*
1383 * ext2_try_to_allocate marked the blocks we allocated as in
1384 * use. So we may want to selectively mark some of the blocks
1385 * as free
1386 */
1387 goto retry_alloc;
1388 }
1389
1390 performed_allocation = 1;
1391
1392 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1393 ext2_error(sb, "ext2_new_blocks",
1394 "block("E2FSBLK") >= blocks count(%d) - "
1395 "block_group = %d, es == %p ", ret_block,
1396 le32_to_cpu(es->s_blocks_count), group_no, es);
1397 goto out;
1398 }
1399
1400 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1401 percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1402
1403 mark_buffer_dirty(bitmap_bh);
1404 if (sb->s_flags & MS_SYNCHRONOUS)
1405 sync_dirty_buffer(bitmap_bh);
1406
1407 *errp = 0;
1408 brelse(bitmap_bh);
1409 if (num < *count) {
1410 dquot_free_block_nodirty(inode, *count-num);
1411 mark_inode_dirty(inode);
1412 *count = num;
1413 }
1414 return ret_block;
1415
1416io_error:
1417 *errp = -EIO;
1418out:
1419 /*
1420 * Undo the block allocation
1421 */
1422 if (!performed_allocation) {
1423 dquot_free_block_nodirty(inode, *count);
1424 mark_inode_dirty(inode);
1425 }
1426 brelse(bitmap_bh);
1427 return 0;
1428}
1429
1430ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1431{
1432 unsigned long count = 1;
1433
1434 return ext2_new_blocks(inode, goal, &count, errp);
1435}
1436
1437#ifdef EXT2FS_DEBUG
1438
1439unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
1440{
1441 return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
1442}
1443
1444#endif /* EXT2FS_DEBUG */
1445
1446unsigned long ext2_count_free_blocks (struct super_block * sb)
1447{
1448 struct ext2_group_desc * desc;
1449 unsigned long desc_count = 0;
1450 int i;
1451#ifdef EXT2FS_DEBUG
1452 unsigned long bitmap_count, x;
1453 struct ext2_super_block *es;
1454
1455 es = EXT2_SB(sb)->s_es;
1456 desc_count = 0;
1457 bitmap_count = 0;
1458 desc = NULL;
1459 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1460 struct buffer_head *bitmap_bh;
1461 desc = ext2_get_group_desc (sb, i, NULL);
1462 if (!desc)
1463 continue;
1464 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1465 bitmap_bh = read_block_bitmap(sb, i);
1466 if (!bitmap_bh)
1467 continue;
1468
1469 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1470 printk ("group %d: stored = %d, counted = %lu\n",
1471 i, le16_to_cpu(desc->bg_free_blocks_count), x);
1472 bitmap_count += x;
1473 brelse(bitmap_bh);
1474 }
1475 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1476 (long)le32_to_cpu(es->s_free_blocks_count),
1477 desc_count, bitmap_count);
1478 return bitmap_count;
1479#else
1480 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
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 }
1486 return desc_count;
1487#endif
1488}
1489
1490static inline int test_root(int a, int b)
1491{
1492 int num = b;
1493
1494 while (a > num)
1495 num *= b;
1496 return num == a;
1497}
1498
1499static int ext2_group_sparse(int group)
1500{
1501 if (group <= 1)
1502 return 1;
1503 return (test_root(group, 3) || test_root(group, 5) ||
1504 test_root(group, 7));
1505}
1506
1507/**
1508 * ext2_bg_has_super - number of blocks used by the superblock in group
1509 * @sb: superblock for filesystem
1510 * @group: group number to check
1511 *
1512 * Return the number of blocks used by the superblock (primary or backup)
1513 * in this group. Currently this will be only 0 or 1.
1514 */
1515int ext2_bg_has_super(struct super_block *sb, int group)
1516{
1517 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1518 !ext2_group_sparse(group))
1519 return 0;
1520 return 1;
1521}
1522
1523/**
1524 * ext2_bg_num_gdb - number of blocks used by the group table in group
1525 * @sb: superblock for filesystem
1526 * @group: group number to check
1527 *
1528 * Return the number of blocks used by the group descriptor table
1529 * (primary or backup) in this group. In the future there may be a
1530 * different number of descriptor blocks in each group.
1531 */
1532unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1533{
1534 return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1535}
1536