blob: 377ad172d74b1c5e8110393d875d5499f9bfe199 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include "ext2.h"
15#include <linux/quotaops.h>
16#include <linux/sched.h>
17#include <linux/buffer_head.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080018#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019
20/*
21 * balloc.c contains the blocks allocation and deallocation routines
22 */
23
24/*
25 * The free blocks are managed by bitmaps. A file system contains several
26 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
27 * block for inodes, N blocks for the inode table and data blocks.
28 *
29 * The file system contains group descriptors which are located after the
30 * super block. Each descriptor contains the number of the bitmap block and
31 * the free blocks count in the block. The descriptors are loaded in memory
Aneesh Kumar K.Ve6274322007-02-20 13:57:58 -080032 * when a file system is mounted (see ext2_fill_super).
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 */
34
35
36#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
37
38struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
39 unsigned int block_group,
40 struct buffer_head ** bh)
41{
42 unsigned long group_desc;
43 unsigned long offset;
44 struct ext2_group_desc * desc;
45 struct ext2_sb_info *sbi = EXT2_SB(sb);
46
47 if (block_group >= sbi->s_groups_count) {
48 ext2_error (sb, "ext2_get_group_desc",
49 "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 ext2_error (sb, "ext2_get_group_desc",
60 "Group descriptor not loaded - "
61 "block_group = %d, group_desc = %lu, desc = %lu",
62 block_group, group_desc, offset);
63 return NULL;
64 }
65
66 desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;
67 if (bh)
68 *bh = sbi->s_group_desc[group_desc];
69 return desc + offset;
70}
71
72/*
73 * Read the bitmap for a given block_group, reading into the specified
74 * slot in the superblock's bitmap cache.
75 *
76 * Return buffer_head on success or NULL in case of failure.
77 */
78static struct buffer_head *
79read_block_bitmap(struct super_block *sb, unsigned int block_group)
80{
81 struct ext2_group_desc * desc;
82 struct buffer_head * bh = NULL;
Linus Torvalds0b832a42007-11-13 08:07:31 -080083
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 desc = ext2_get_group_desc (sb, block_group, NULL);
85 if (!desc)
Linus Torvalds0b832a42007-11-13 08:07:31 -080086 goto error_out;
87 bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 if (!bh)
Linus Torvalds0b832a42007-11-13 08:07:31 -080089 ext2_error (sb, "read_block_bitmap",
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 "Cannot read block bitmap - "
91 "block_group = %d, block_bitmap = %u",
92 block_group, le32_to_cpu(desc->bg_block_bitmap));
Aneesh Kumar K.V7c9e69f2007-10-16 23:27:02 -070093error_out:
Linus Torvalds0b832a42007-11-13 08:07:31 -080094 return bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -070095}
96
Linus Torvalds1da177e2005-04-16 15:20:36 -070097static void release_blocks(struct super_block *sb, int count)
98{
99 if (count) {
100 struct ext2_sb_info *sbi = EXT2_SB(sb);
101
Peter Zijlstraaa0dff22007-10-16 23:25:42 -0700102 percpu_counter_add(&sbi->s_freeblocks_counter, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 sb->s_dirt = 1;
104 }
105}
106
Martin J. Bligha686cd82007-10-16 23:30:46 -0700107static void group_adjust_blocks(struct super_block *sb, int group_no,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 struct ext2_group_desc *desc, struct buffer_head *bh, int count)
109{
110 if (count) {
111 struct ext2_sb_info *sbi = EXT2_SB(sb);
112 unsigned free_blocks;
113
114 spin_lock(sb_bgl_lock(sbi, group_no));
115 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
116 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
117 spin_unlock(sb_bgl_lock(sbi, group_no));
118 sb->s_dirt = 1;
119 mark_buffer_dirty(bh);
120 }
121}
122
Martin J. Bligha686cd82007-10-16 23:30:46 -0700123/*
124 * The reservation window structure operations
125 * --------------------------------------------
126 * Operations include:
127 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
128 *
129 * We use a red-black tree to represent per-filesystem reservation
130 * windows.
131 *
132 */
133
134/**
135 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
136 * @rb_root: root of per-filesystem reservation rb tree
137 * @verbose: verbose mode
138 * @fn: function which wishes to dump the reservation map
139 *
140 * If verbose is turned on, it will print the whole block reservation
141 * windows(start, end). Otherwise, it will only print out the "bad" windows,
142 * those windows that overlap with their immediate neighbors.
143 */
144#if 1
145static void __rsv_window_dump(struct rb_root *root, int verbose,
146 const char *fn)
147{
148 struct rb_node *n;
149 struct ext2_reserve_window_node *rsv, *prev;
150 int bad;
151
152restart:
153 n = rb_first(root);
154 bad = 0;
155 prev = NULL;
156
157 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
158 while (n) {
159 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
160 if (verbose)
161 printk("reservation window 0x%p "
162 "start: %lu, end: %lu\n",
163 rsv, rsv->rsv_start, rsv->rsv_end);
164 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
165 printk("Bad reservation %p (start >= end)\n",
166 rsv);
167 bad = 1;
168 }
169 if (prev && prev->rsv_end >= rsv->rsv_start) {
170 printk("Bad reservation %p (prev->end >= start)\n",
171 rsv);
172 bad = 1;
173 }
174 if (bad) {
175 if (!verbose) {
176 printk("Restarting reservation walk in verbose mode\n");
177 verbose = 1;
178 goto restart;
179 }
180 }
181 n = rb_next(n);
182 prev = rsv;
183 }
184 printk("Window map complete.\n");
185 if (bad)
186 BUG();
187}
188#define rsv_window_dump(root, verbose) \
189 __rsv_window_dump((root), (verbose), __FUNCTION__)
190#else
191#define rsv_window_dump(root, verbose) do {} while (0)
192#endif
193
194/**
195 * goal_in_my_reservation()
196 * @rsv: inode's reservation window
197 * @grp_goal: given goal block relative to the allocation block group
198 * @group: the current allocation block group
199 * @sb: filesystem super block
200 *
201 * Test if the given goal block (group relative) is within the file's
202 * own block reservation window range.
203 *
204 * If the reservation window is outside the goal allocation group, return 0;
205 * grp_goal (given goal block) could be -1, which means no specific
206 * goal block. In this case, always return 1.
207 * If the goal block is within the reservation window, return 1;
208 * otherwise, return 0;
209 */
210static int
211goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
212 unsigned int group, struct super_block * sb)
213{
214 ext2_fsblk_t group_first_block, group_last_block;
215
216 group_first_block = ext2_group_first_block_no(sb, group);
217 group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
218
219 if ((rsv->_rsv_start > group_last_block) ||
220 (rsv->_rsv_end < group_first_block))
221 return 0;
222 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
223 || (grp_goal + group_first_block > rsv->_rsv_end)))
224 return 0;
225 return 1;
226}
227
228/**
229 * search_reserve_window()
230 * @rb_root: root of reservation tree
231 * @goal: target allocation block
232 *
233 * Find the reserved window which includes the goal, or the previous one
234 * if the goal is not in any window.
235 * Returns NULL if there are no windows or if all windows start after the goal.
236 */
237static struct ext2_reserve_window_node *
238search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
239{
240 struct rb_node *n = root->rb_node;
241 struct ext2_reserve_window_node *rsv;
242
243 if (!n)
244 return NULL;
245
246 do {
247 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
248
249 if (goal < rsv->rsv_start)
250 n = n->rb_left;
251 else if (goal > rsv->rsv_end)
252 n = n->rb_right;
253 else
254 return rsv;
255 } while (n);
256 /*
257 * We've fallen off the end of the tree: the goal wasn't inside
258 * any particular node. OK, the previous node must be to one
259 * side of the interval containing the goal. If it's the RHS,
260 * we need to back up one.
261 */
262 if (rsv->rsv_start > goal) {
263 n = rb_prev(&rsv->rsv_node);
264 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
265 }
266 return rsv;
267}
268
269/*
270 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
271 * @sb: super block
272 * @rsv: reservation window to add
273 *
274 * Must be called with rsv_lock held.
275 */
276void ext2_rsv_window_add(struct super_block *sb,
277 struct ext2_reserve_window_node *rsv)
278{
279 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
280 struct rb_node *node = &rsv->rsv_node;
281 ext2_fsblk_t start = rsv->rsv_start;
282
283 struct rb_node ** p = &root->rb_node;
284 struct rb_node * parent = NULL;
285 struct ext2_reserve_window_node *this;
286
287 while (*p)
288 {
289 parent = *p;
290 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
291
292 if (start < this->rsv_start)
293 p = &(*p)->rb_left;
294 else if (start > this->rsv_end)
295 p = &(*p)->rb_right;
296 else {
297 rsv_window_dump(root, 1);
298 BUG();
299 }
300 }
301
302 rb_link_node(node, parent, p);
303 rb_insert_color(node, root);
304}
305
306/**
307 * rsv_window_remove() -- unlink a window from the reservation rb tree
308 * @sb: super block
309 * @rsv: reservation window to remove
310 *
311 * Mark the block reservation window as not allocated, and unlink it
312 * from the filesystem reservation window rb tree. Must be called with
313 * rsv_lock held.
314 */
315static void rsv_window_remove(struct super_block *sb,
316 struct ext2_reserve_window_node *rsv)
317{
318 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
319 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
320 rsv->rsv_alloc_hit = 0;
321 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
322}
323
324/*
325 * rsv_is_empty() -- Check if the reservation window is allocated.
326 * @rsv: given reservation window to check
327 *
328 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
329 */
330static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
331{
332 /* a valid reservation end block could not be 0 */
333 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
334}
335
336/**
337 * ext2_init_block_alloc_info()
338 * @inode: file inode structure
339 *
340 * Allocate and initialize the reservation window structure, and
341 * link the window to the ext2 inode structure at last
342 *
343 * The reservation window structure is only dynamically allocated
344 * and linked to ext2 inode the first time the open file
345 * needs a new block. So, before every ext2_new_block(s) call, for
346 * regular files, we should check whether the reservation window
347 * structure exists or not. In the latter case, this function is called.
348 * Fail to do so will result in block reservation being turned off for that
349 * open file.
350 *
351 * This function is called from ext2_get_blocks_handle(), also called
352 * when setting the reservation window size through ioctl before the file
353 * is open for write (needs block allocation).
354 *
355 * Needs truncate_mutex protection prior to calling this function.
356 */
357void ext2_init_block_alloc_info(struct inode *inode)
358{
359 struct ext2_inode_info *ei = EXT2_I(inode);
360 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
361 struct super_block *sb = inode->i_sb;
362
363 block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
364 if (block_i) {
365 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
366
367 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
368 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
369
370 /*
371 * if filesystem is mounted with NORESERVATION, the goal
372 * reservation window size is set to zero to indicate
373 * block reservation is off
374 */
375 if (!test_opt(sb, RESERVATION))
376 rsv->rsv_goal_size = 0;
377 else
378 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
379 rsv->rsv_alloc_hit = 0;
380 block_i->last_alloc_logical_block = 0;
381 block_i->last_alloc_physical_block = 0;
382 }
383 ei->i_block_alloc_info = block_i;
384}
385
386/**
387 * ext2_discard_reservation()
388 * @inode: inode
389 *
390 * Discard(free) block reservation window on last file close, or truncate
391 * or at last iput().
392 *
393 * It is being called in three cases:
394 * ext2_release_file(): last writer closes the file
395 * ext2_clear_inode(): last iput(), when nobody links to this file.
396 * ext2_truncate(): when the block indirect map is about to change.
397 */
398void ext2_discard_reservation(struct inode *inode)
399{
400 struct ext2_inode_info *ei = EXT2_I(inode);
401 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
402 struct ext2_reserve_window_node *rsv;
403 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
404
405 if (!block_i)
406 return;
407
408 rsv = &block_i->rsv_window_node;
409 if (!rsv_is_empty(&rsv->rsv_window)) {
410 spin_lock(rsv_lock);
411 if (!rsv_is_empty(&rsv->rsv_window))
412 rsv_window_remove(inode->i_sb, rsv);
413 spin_unlock(rsv_lock);
414 }
415}
416
417/**
418 * ext2_free_blocks_sb() -- Free given blocks and update quota and i_blocks
419 * @inode: inode
420 * @block: start physcial block to free
421 * @count: number of blocks to free
422 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423void ext2_free_blocks (struct inode * inode, unsigned long block,
424 unsigned long count)
425{
426 struct buffer_head *bitmap_bh = NULL;
427 struct buffer_head * bh2;
428 unsigned long block_group;
429 unsigned long bit;
430 unsigned long i;
431 unsigned long overflow;
432 struct super_block * sb = inode->i_sb;
433 struct ext2_sb_info * sbi = EXT2_SB(sb);
434 struct ext2_group_desc * desc;
435 struct ext2_super_block * es = sbi->s_es;
436 unsigned freed = 0, group_freed;
437
438 if (block < le32_to_cpu(es->s_first_data_block) ||
439 block + count < block ||
440 block + count > le32_to_cpu(es->s_blocks_count)) {
441 ext2_error (sb, "ext2_free_blocks",
442 "Freeing blocks not in datazone - "
443 "block = %lu, count = %lu", block, count);
444 goto error_return;
445 }
446
447 ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
448
449do_more:
450 overflow = 0;
451 block_group = (block - le32_to_cpu(es->s_first_data_block)) /
452 EXT2_BLOCKS_PER_GROUP(sb);
453 bit = (block - le32_to_cpu(es->s_first_data_block)) %
454 EXT2_BLOCKS_PER_GROUP(sb);
455 /*
456 * Check to see if we are freeing blocks across a group
457 * boundary.
458 */
459 if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
460 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
461 count -= overflow;
462 }
463 brelse(bitmap_bh);
464 bitmap_bh = read_block_bitmap(sb, block_group);
465 if (!bitmap_bh)
466 goto error_return;
467
468 desc = ext2_get_group_desc (sb, block_group, &bh2);
469 if (!desc)
470 goto error_return;
471
472 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
473 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
474 in_range (block, le32_to_cpu(desc->bg_inode_table),
475 sbi->s_itb_per_group) ||
476 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
477 sbi->s_itb_per_group))
478 ext2_error (sb, "ext2_free_blocks",
479 "Freeing blocks in system zones - "
480 "Block = %lu, count = %lu",
481 block, count);
482
483 for (i = 0, group_freed = 0; i < count; i++) {
484 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
485 bit + i, bitmap_bh->b_data)) {
486 ext2_error(sb, __FUNCTION__,
487 "bit already cleared for block %lu", block + i);
488 } else {
489 group_freed++;
490 }
491 }
492
493 mark_buffer_dirty(bitmap_bh);
494 if (sb->s_flags & MS_SYNCHRONOUS)
495 sync_dirty_buffer(bitmap_bh);
496
Martin J. Bligha686cd82007-10-16 23:30:46 -0700497 group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 freed += group_freed;
499
500 if (overflow) {
501 block += count;
502 count = overflow;
503 goto do_more;
504 }
505error_return:
506 brelse(bitmap_bh);
507 release_blocks(sb, freed);
508 DQUOT_FREE_BLOCK(inode, freed);
509}
510
Martin J. Bligha686cd82007-10-16 23:30:46 -0700511/**
512 * bitmap_search_next_usable_block()
513 * @start: the starting block (group relative) of the search
514 * @bh: bufferhead contains the block group bitmap
515 * @maxblocks: the ending block (group relative) of the reservation
516 *
517 * The bitmap search --- search forward through the actual bitmap on disk until
518 * we find a bit free.
519 */
520static ext2_grpblk_t
521bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
522 ext2_grpblk_t maxblocks)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523{
Martin J. Bligha686cd82007-10-16 23:30:46 -0700524 ext2_grpblk_t next;
525
526 next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
527 if (next >= maxblocks)
528 return -1;
529 return next;
530}
531
532/**
533 * find_next_usable_block()
534 * @start: the starting block (group relative) to find next
535 * allocatable block in bitmap.
536 * @bh: bufferhead contains the block group bitmap
537 * @maxblocks: the ending block (group relative) for the search
538 *
539 * Find an allocatable block in a bitmap. We perform the "most
540 * appropriate allocation" algorithm of looking for a free block near
541 * the initial goal; then for a free byte somewhere in the bitmap;
542 * then for any free bit in the bitmap.
543 */
544static ext2_grpblk_t
545find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
546{
547 ext2_grpblk_t here, next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 char *p, *r;
549
Martin J. Bligha686cd82007-10-16 23:30:46 -0700550 if (start > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 /*
552 * The goal was occupied; search forward for a free
553 * block within the next XX blocks.
554 *
555 * end_goal is more or less random, but it has to be
556 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
557 * next 64-bit boundary is simple..
558 */
Martin J. Bligha686cd82007-10-16 23:30:46 -0700559 ext2_grpblk_t end_goal = (start + 63) & ~63;
560 if (end_goal > maxblocks)
561 end_goal = maxblocks;
562 here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
563 if (here < end_goal)
564 return here;
565 ext2_debug("Bit not found near goal\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 }
567
Martin J. Bligha686cd82007-10-16 23:30:46 -0700568 here = start;
569 if (here < 0)
570 here = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
Martin J. Bligha686cd82007-10-16 23:30:46 -0700572 p = ((char *)bh->b_data) + (here >> 3);
573 r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
574 next = (r - ((char *)bh->b_data)) << 3;
575
576 if (next < maxblocks && next >= here)
577 return next;
578
579 here = bitmap_search_next_usable_block(here, bh, maxblocks);
580 return here;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581}
582
583/*
Martin J. Bligha686cd82007-10-16 23:30:46 -0700584 * ext2_try_to_allocate()
585 * @sb: superblock
586 * @handle: handle to this transaction
587 * @group: given allocation block group
588 * @bitmap_bh: bufferhead holds the block bitmap
589 * @grp_goal: given target block within the group
590 * @count: target number of blocks to allocate
591 * @my_rsv: reservation window
592 *
593 * Attempt to allocate blocks within a give range. Set the range of allocation
594 * first, then find the first free bit(s) from the bitmap (within the range),
595 * and at last, allocate the blocks by claiming the found free bit as allocated.
596 *
597 * To set the range of this allocation:
598 * if there is a reservation window, only try to allocate block(s)
599 * from the file's own reservation window;
600 * Otherwise, the allocation range starts from the give goal block,
601 * ends at the block group's last block.
602 *
603 * If we failed to allocate the desired block then we may end up crossing to a
604 * new bitmap.
605 */
606static int
607ext2_try_to_allocate(struct super_block *sb, int group,
608 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
609 unsigned long *count,
610 struct ext2_reserve_window *my_rsv)
611{
612 ext2_fsblk_t group_first_block;
613 ext2_grpblk_t start, end;
614 unsigned long num = 0;
615
616 /* we do allocation within the reservation window if we have a window */
617 if (my_rsv) {
618 group_first_block = ext2_group_first_block_no(sb, group);
619 if (my_rsv->_rsv_start >= group_first_block)
620 start = my_rsv->_rsv_start - group_first_block;
621 else
622 /* reservation window cross group boundary */
623 start = 0;
624 end = my_rsv->_rsv_end - group_first_block + 1;
625 if (end > EXT2_BLOCKS_PER_GROUP(sb))
626 /* reservation window crosses group boundary */
627 end = EXT2_BLOCKS_PER_GROUP(sb);
628 if ((start <= grp_goal) && (grp_goal < end))
629 start = grp_goal;
630 else
631 grp_goal = -1;
632 } else {
633 if (grp_goal > 0)
634 start = grp_goal;
635 else
636 start = 0;
637 end = EXT2_BLOCKS_PER_GROUP(sb);
638 }
639
640 BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
641
642repeat:
643 if (grp_goal < 0) {
644 grp_goal = find_next_usable_block(start, bitmap_bh, end);
645 if (grp_goal < 0)
646 goto fail_access;
647 if (!my_rsv) {
648 int i;
649
650 for (i = 0; i < 7 && grp_goal > start &&
651 !ext2_test_bit(grp_goal - 1,
652 bitmap_bh->b_data);
653 i++, grp_goal--)
654 ;
655 }
656 }
657 start = grp_goal;
658
659 if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
660 bitmap_bh->b_data)) {
661 /*
662 * The block was allocated by another thread, or it was
663 * allocated and then freed by another thread
664 */
665 start++;
666 grp_goal++;
667 if (start >= end)
668 goto fail_access;
669 goto repeat;
670 }
671 num++;
672 grp_goal++;
673 while (num < *count && grp_goal < end
674 && !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
675 grp_goal, bitmap_bh->b_data)) {
676 num++;
677 grp_goal++;
678 }
679 *count = num;
680 return grp_goal - num;
681fail_access:
682 *count = num;
683 return -1;
684}
685
686/**
687 * find_next_reservable_window():
688 * find a reservable space within the given range.
689 * It does not allocate the reservation window for now:
690 * alloc_new_reservation() will do the work later.
691 *
692 * @search_head: the head of the searching list;
693 * This is not necessarily the list head of the whole filesystem
694 *
695 * We have both head and start_block to assist the search
696 * for the reservable space. The list starts from head,
697 * but we will shift to the place where start_block is,
698 * then start from there, when looking for a reservable space.
699 *
700 * @size: the target new reservation window size
701 *
702 * @group_first_block: the first block we consider to start
703 * the real search from
704 *
705 * @last_block:
706 * the maximum block number that our goal reservable space
707 * could start from. This is normally the last block in this
708 * group. The search will end when we found the start of next
709 * possible reservable space is out of this boundary.
710 * This could handle the cross boundary reservation window
711 * request.
712 *
713 * basically we search from the given range, rather than the whole
714 * reservation double linked list, (start_block, last_block)
715 * to find a free region that is of my size and has not
716 * been reserved.
717 *
718 */
719static int find_next_reservable_window(
720 struct ext2_reserve_window_node *search_head,
721 struct ext2_reserve_window_node *my_rsv,
722 struct super_block * sb,
723 ext2_fsblk_t start_block,
724 ext2_fsblk_t last_block)
725{
726 struct rb_node *next;
727 struct ext2_reserve_window_node *rsv, *prev;
728 ext2_fsblk_t cur;
729 int size = my_rsv->rsv_goal_size;
730
731 /* TODO: make the start of the reservation window byte-aligned */
732 /* cur = *start_block & ~7;*/
733 cur = start_block;
734 rsv = search_head;
735 if (!rsv)
736 return -1;
737
738 while (1) {
739 if (cur <= rsv->rsv_end)
740 cur = rsv->rsv_end + 1;
741
742 /* TODO?
743 * in the case we could not find a reservable space
744 * that is what is expected, during the re-search, we could
745 * remember what's the largest reservable space we could have
746 * and return that one.
747 *
748 * For now it will fail if we could not find the reservable
749 * space with expected-size (or more)...
750 */
751 if (cur > last_block)
752 return -1; /* fail */
753
754 prev = rsv;
755 next = rb_next(&rsv->rsv_node);
756 rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
757
758 /*
759 * Reached the last reservation, we can just append to the
760 * previous one.
761 */
762 if (!next)
763 break;
764
765 if (cur + size <= rsv->rsv_start) {
766 /*
767 * Found a reserveable space big enough. We could
768 * have a reservation across the group boundary here
769 */
770 break;
771 }
772 }
773 /*
774 * we come here either :
775 * when we reach the end of the whole list,
776 * and there is empty reservable space after last entry in the list.
777 * append it to the end of the list.
778 *
779 * or we found one reservable space in the middle of the list,
780 * return the reservation window that we could append to.
781 * succeed.
782 */
783
784 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
785 rsv_window_remove(sb, my_rsv);
786
787 /*
788 * Let's book the whole avaliable window for now. We will check the
789 * disk bitmap later and then, if there are free blocks then we adjust
790 * the window size if it's larger than requested.
791 * Otherwise, we will remove this node from the tree next time
792 * call find_next_reservable_window.
793 */
794 my_rsv->rsv_start = cur;
795 my_rsv->rsv_end = cur + size - 1;
796 my_rsv->rsv_alloc_hit = 0;
797
798 if (prev != my_rsv)
799 ext2_rsv_window_add(sb, my_rsv);
800
801 return 0;
802}
803
804/**
805 * alloc_new_reservation()--allocate a new reservation window
806 *
807 * To make a new reservation, we search part of the filesystem
808 * reservation list (the list that inside the group). We try to
809 * allocate a new reservation window near the allocation goal,
810 * or the beginning of the group, if there is no goal.
811 *
812 * We first find a reservable space after the goal, then from
813 * there, we check the bitmap for the first free block after
814 * it. If there is no free block until the end of group, then the
815 * whole group is full, we failed. Otherwise, check if the free
816 * block is inside the expected reservable space, if so, we
817 * succeed.
818 * If the first free block is outside the reservable space, then
819 * start from the first free block, we search for next available
820 * space, and go on.
821 *
822 * on succeed, a new reservation will be found and inserted into the list
823 * It contains at least one free block, and it does not overlap with other
824 * reservation windows.
825 *
826 * failed: we failed to find a reservation window in this group
827 *
828 * @rsv: the reservation
829 *
830 * @grp_goal: The goal (group-relative). It is where the search for a
831 * free reservable space should start from.
832 * if we have a goal(goal >0 ), then start from there,
833 * no goal(goal = -1), we start from the first block
834 * of the group.
835 *
836 * @sb: the super block
837 * @group: the group we are trying to allocate in
838 * @bitmap_bh: the block group block bitmap
839 *
840 */
841static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
842 ext2_grpblk_t grp_goal, struct super_block *sb,
843 unsigned int group, struct buffer_head *bitmap_bh)
844{
845 struct ext2_reserve_window_node *search_head;
846 ext2_fsblk_t group_first_block, group_end_block, start_block;
847 ext2_grpblk_t first_free_block;
848 struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
849 unsigned long size;
850 int ret;
851 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
852
853 group_first_block = ext2_group_first_block_no(sb, group);
854 group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
855
856 if (grp_goal < 0)
857 start_block = group_first_block;
858 else
859 start_block = grp_goal + group_first_block;
860
861 size = my_rsv->rsv_goal_size;
862
863 if (!rsv_is_empty(&my_rsv->rsv_window)) {
864 /*
865 * if the old reservation is cross group boundary
866 * and if the goal is inside the old reservation window,
867 * we will come here when we just failed to allocate from
868 * the first part of the window. We still have another part
869 * that belongs to the next group. In this case, there is no
870 * point to discard our window and try to allocate a new one
871 * in this group(which will fail). we should
872 * keep the reservation window, just simply move on.
873 *
874 * Maybe we could shift the start block of the reservation
875 * window to the first block of next group.
876 */
877
878 if ((my_rsv->rsv_start <= group_end_block) &&
879 (my_rsv->rsv_end > group_end_block) &&
880 (start_block >= my_rsv->rsv_start))
881 return -1;
882
883 if ((my_rsv->rsv_alloc_hit >
884 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
885 /*
886 * if the previously allocation hit ratio is
887 * greater than 1/2, then we double the size of
888 * the reservation window the next time,
889 * otherwise we keep the same size window
890 */
891 size = size * 2;
892 if (size > EXT2_MAX_RESERVE_BLOCKS)
893 size = EXT2_MAX_RESERVE_BLOCKS;
894 my_rsv->rsv_goal_size= size;
895 }
896 }
897
898 spin_lock(rsv_lock);
899 /*
900 * shift the search start to the window near the goal block
901 */
902 search_head = search_reserve_window(fs_rsv_root, start_block);
903
904 /*
905 * find_next_reservable_window() simply finds a reservable window
906 * inside the given range(start_block, group_end_block).
907 *
908 * To make sure the reservation window has a free bit inside it, we
909 * need to check the bitmap after we found a reservable window.
910 */
911retry:
912 ret = find_next_reservable_window(search_head, my_rsv, sb,
913 start_block, group_end_block);
914
915 if (ret == -1) {
916 if (!rsv_is_empty(&my_rsv->rsv_window))
917 rsv_window_remove(sb, my_rsv);
918 spin_unlock(rsv_lock);
919 return -1;
920 }
921
922 /*
923 * On success, find_next_reservable_window() returns the
924 * reservation window where there is a reservable space after it.
925 * Before we reserve this reservable space, we need
926 * to make sure there is at least a free block inside this region.
927 *
928 * Search the first free bit on the block bitmap. Search starts from
929 * the start block of the reservable space we just found.
930 */
931 spin_unlock(rsv_lock);
932 first_free_block = bitmap_search_next_usable_block(
933 my_rsv->rsv_start - group_first_block,
934 bitmap_bh, group_end_block - group_first_block + 1);
935
936 if (first_free_block < 0) {
937 /*
938 * no free block left on the bitmap, no point
939 * to reserve the space. return failed.
940 */
941 spin_lock(rsv_lock);
942 if (!rsv_is_empty(&my_rsv->rsv_window))
943 rsv_window_remove(sb, my_rsv);
944 spin_unlock(rsv_lock);
945 return -1; /* failed */
946 }
947
948 start_block = first_free_block + group_first_block;
949 /*
950 * check if the first free block is within the
951 * free space we just reserved
952 */
953 if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
954 return 0; /* success */
955 /*
956 * if the first free bit we found is out of the reservable space
957 * continue search for next reservable space,
958 * start from where the free block is,
959 * we also shift the list head to where we stopped last time
960 */
961 search_head = my_rsv;
962 spin_lock(rsv_lock);
963 goto retry;
964}
965
966/**
967 * try_to_extend_reservation()
968 * @my_rsv: given reservation window
969 * @sb: super block
970 * @size: the delta to extend
971 *
972 * Attempt to expand the reservation window large enough to have
973 * required number of free blocks
974 *
975 * Since ext2_try_to_allocate() will always allocate blocks within
976 * the reservation window range, if the window size is too small,
977 * multiple blocks allocation has to stop at the end of the reservation
978 * window. To make this more efficient, given the total number of
979 * blocks needed and the current size of the window, we try to
980 * expand the reservation window size if necessary on a best-effort
981 * basis before ext2_new_blocks() tries to allocate blocks.
982 */
983static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
984 struct super_block *sb, int size)
985{
986 struct ext2_reserve_window_node *next_rsv;
987 struct rb_node *next;
988 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
989
990 if (!spin_trylock(rsv_lock))
991 return;
992
993 next = rb_next(&my_rsv->rsv_node);
994
995 if (!next)
996 my_rsv->rsv_end += size;
997 else {
998 next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
999
1000 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1001 my_rsv->rsv_end += size;
1002 else
1003 my_rsv->rsv_end = next_rsv->rsv_start - 1;
1004 }
1005 spin_unlock(rsv_lock);
1006}
1007
1008/**
1009 * ext2_try_to_allocate_with_rsv()
1010 * @sb: superblock
1011 * @group: given allocation block group
1012 * @bitmap_bh: bufferhead holds the block bitmap
1013 * @grp_goal: given target block within the group
1014 * @count: target number of blocks to allocate
1015 * @my_rsv: reservation window
1016 *
1017 * This is the main function used to allocate a new block and its reservation
1018 * window.
1019 *
1020 * Each time when a new block allocation is need, first try to allocate from
1021 * its own reservation. If it does not have a reservation window, instead of
1022 * looking for a free bit on bitmap first, then look up the reservation list to
1023 * see if it is inside somebody else's reservation window, we try to allocate a
1024 * reservation window for it starting from the goal first. Then do the block
1025 * allocation within the reservation window.
1026 *
1027 * This will avoid keeping on searching the reservation list again and
1028 * again when somebody is looking for a free block (without
1029 * reservation), and there are lots of free blocks, but they are all
1030 * being reserved.
1031 *
1032 * We use a red-black tree for the per-filesystem reservation list.
1033 */
1034static ext2_grpblk_t
1035ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1036 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1037 struct ext2_reserve_window_node * my_rsv,
1038 unsigned long *count)
1039{
1040 ext2_fsblk_t group_first_block, group_last_block;
1041 ext2_grpblk_t ret = 0;
1042 unsigned long num = *count;
1043
1044 /*
1045 * we don't deal with reservation when
1046 * filesystem is mounted without reservation
1047 * or the file is not a regular file
1048 * or last attempt to allocate a block with reservation turned on failed
1049 */
1050 if (my_rsv == NULL) {
1051 return ext2_try_to_allocate(sb, group, bitmap_bh,
1052 grp_goal, count, NULL);
1053 }
1054 /*
1055 * grp_goal is a group relative block number (if there is a goal)
1056 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1057 * first block is a filesystem wide block number
1058 * first block is the block number of the first block in this group
1059 */
1060 group_first_block = ext2_group_first_block_no(sb, group);
1061 group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
1062
1063 /*
1064 * Basically we will allocate a new block from inode's reservation
1065 * window.
1066 *
1067 * We need to allocate a new reservation window, if:
1068 * a) inode does not have a reservation window; or
1069 * b) last attempt to allocate a block from existing reservation
1070 * failed; or
1071 * c) we come here with a goal and with a reservation window
1072 *
1073 * We do not need to allocate a new reservation window if we come here
1074 * at the beginning with a goal and the goal is inside the window, or
1075 * we don't have a goal but already have a reservation window.
1076 * then we could go to allocate from the reservation window directly.
1077 */
1078 while (1) {
1079 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1080 !goal_in_my_reservation(&my_rsv->rsv_window,
1081 grp_goal, group, sb)) {
1082 if (my_rsv->rsv_goal_size < *count)
1083 my_rsv->rsv_goal_size = *count;
1084 ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1085 group, bitmap_bh);
1086 if (ret < 0)
1087 break; /* failed */
1088
1089 if (!goal_in_my_reservation(&my_rsv->rsv_window,
1090 grp_goal, group, sb))
1091 grp_goal = -1;
1092 } else if (grp_goal >= 0) {
1093 int curr = my_rsv->rsv_end -
1094 (grp_goal + group_first_block) + 1;
1095
1096 if (curr < *count)
1097 try_to_extend_reservation(my_rsv, sb,
1098 *count - curr);
1099 }
1100
1101 if ((my_rsv->rsv_start > group_last_block) ||
1102 (my_rsv->rsv_end < group_first_block)) {
1103 rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1104 BUG();
1105 }
1106 ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1107 &num, &my_rsv->rsv_window);
1108 if (ret >= 0) {
1109 my_rsv->rsv_alloc_hit += num;
1110 *count = num;
1111 break; /* succeed */
1112 }
1113 num = *count;
1114 }
1115 return ret;
1116}
1117
1118/**
1119 * ext2_has_free_blocks()
1120 * @sbi: in-core super block structure.
1121 *
1122 * Check if filesystem has at least 1 free block available for allocation.
1123 */
1124static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1125{
1126 ext2_fsblk_t free_blocks, root_blocks;
1127
1128 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1129 root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1130 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1131 sbi->s_resuid != current->fsuid &&
1132 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1133 return 0;
1134 }
1135 return 1;
1136}
1137
1138/*
1139 * ext2_new_blocks() -- core block(s) allocation function
1140 * @inode: file inode
1141 * @goal: given target block(filesystem wide)
1142 * @count: target number of blocks to allocate
1143 * @errp: error code
1144 *
1145 * ext2_new_blocks uses a goal block to assist allocation. If the goal is
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146 * free, or there is a free block within 32 blocks of the goal, that block
1147 * is allocated. Otherwise a forward search is made for a free block; within
1148 * each block group the search first looks for an entire free byte in the block
1149 * bitmap, and then for any free bit if that fails.
1150 * This function also updates quota and i_blocks field.
1151 */
Martin J. Bligha686cd82007-10-16 23:30:46 -07001152ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1153 unsigned long *count, int *errp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154{
1155 struct buffer_head *bitmap_bh = NULL;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001156 struct buffer_head *gdp_bh;
1157 int group_no;
1158 int goal_group;
1159 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1160 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1161 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1162 int bgi; /* blockgroup iteration index */
1163 int performed_allocation = 0;
1164 ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1165 struct super_block *sb;
1166 struct ext2_group_desc *gdp;
1167 struct ext2_super_block *es;
1168 struct ext2_sb_info *sbi;
1169 struct ext2_reserve_window_node *my_rsv = NULL;
1170 struct ext2_block_alloc_info *block_i;
1171 unsigned short windowsz = 0;
1172 unsigned long ngroups;
1173 unsigned long num = *count;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174
Martin J. Bligha686cd82007-10-16 23:30:46 -07001175 *errp = -ENOSPC;
1176 sb = inode->i_sb;
1177 if (!sb) {
1178 printk("ext2_new_blocks: nonexistent device");
1179 return 0;
1180 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181
Martin J. Bligha686cd82007-10-16 23:30:46 -07001182 /*
1183 * Check quota for allocation of this block.
1184 */
1185 if (DQUOT_ALLOC_BLOCK(inode, num)) {
1186 *errp = -EDQUOT;
1187 return 0;
1188 }
1189
1190 sbi = EXT2_SB(sb);
1191 es = EXT2_SB(sb)->s_es;
1192 ext2_debug("goal=%lu.\n", goal);
1193 /*
1194 * Allocate a block from reservation only when
1195 * filesystem is mounted with reservation(default,-o reservation), and
1196 * it's a regular file, and
1197 * the desired window size is greater than 0 (One could use ioctl
1198 * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1199 * reservation on that particular file)
1200 */
1201 block_i = EXT2_I(inode)->i_block_alloc_info;
1202 if (block_i) {
1203 windowsz = block_i->rsv_window_node.rsv_goal_size;
1204 if (windowsz > 0)
1205 my_rsv = &block_i->rsv_window_node;
1206 }
1207
1208 if (!ext2_has_free_blocks(sbi)) {
1209 *errp = -ENOSPC;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 goto out;
1211 }
1212
Martin J. Bligha686cd82007-10-16 23:30:46 -07001213 /*
1214 * First, test whether the goal block is free.
1215 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 if (goal < le32_to_cpu(es->s_first_data_block) ||
1217 goal >= le32_to_cpu(es->s_blocks_count))
1218 goal = le32_to_cpu(es->s_first_data_block);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001219 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1220 EXT2_BLOCKS_PER_GROUP(sb);
1221 goal_group = group_no;
1222retry_alloc:
1223 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1224 if (!gdp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 goto io_error;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001226
1227 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1228 /*
1229 * if there is not enough free blocks to make a new resevation
1230 * turn off reservation for this allocation
1231 */
1232 if (my_rsv && (free_blocks < windowsz)
1233 && (rsv_is_empty(&my_rsv->rsv_window)))
1234 my_rsv = NULL;
1235
1236 if (free_blocks > 0) {
1237 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1238 EXT2_BLOCKS_PER_GROUP(sb));
1239 bitmap_bh = read_block_bitmap(sb, group_no);
1240 if (!bitmap_bh)
1241 goto io_error;
1242 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1243 bitmap_bh, grp_target_blk,
1244 my_rsv, &num);
1245 if (grp_alloc_blk >= 0)
1246 goto allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247 }
1248
Martin J. Bligha686cd82007-10-16 23:30:46 -07001249 ngroups = EXT2_SB(sb)->s_groups_count;
1250 smp_rmb();
1251
1252 /*
1253 * Now search the rest of the groups. We assume that
1254 * i and gdp correctly point to the last group visited.
1255 */
1256 for (bgi = 0; bgi < ngroups; bgi++) {
1257 group_no++;
1258 if (group_no >= ngroups)
1259 group_no = 0;
1260 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1261 if (!gdp)
1262 goto io_error;
1263
1264 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1265 /*
1266 * skip this group if the number of
1267 * free blocks is less than half of the reservation
1268 * window size.
1269 */
1270 if (free_blocks <= (windowsz/2))
1271 continue;
1272
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273 brelse(bitmap_bh);
1274 bitmap_bh = read_block_bitmap(sb, group_no);
1275 if (!bitmap_bh)
1276 goto io_error;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001277 /*
1278 * try to allocate block(s) from this group, without a goal(-1).
1279 */
1280 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1281 bitmap_bh, -1, my_rsv, &num);
1282 if (grp_alloc_blk >= 0)
1283 goto allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 /*
Martin J. Bligha686cd82007-10-16 23:30:46 -07001286 * We may end up a bogus ealier ENOSPC error due to
1287 * filesystem is "full" of reservations, but
1288 * there maybe indeed free blocks avaliable on disk
1289 * In this case, we just forget about the reservations
1290 * just do block allocation as without reservations.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291 */
Martin J. Bligha686cd82007-10-16 23:30:46 -07001292 if (my_rsv) {
1293 my_rsv = NULL;
1294 windowsz = 0;
1295 group_no = goal_group;
1296 goto retry_alloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 }
Martin J. Bligha686cd82007-10-16 23:30:46 -07001298 /* No space left on the device */
1299 *errp = -ENOSPC;
1300 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301
Martin J. Bligha686cd82007-10-16 23:30:46 -07001302allocated:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 ext2_debug("using block group %d(%d)\n",
Martin J. Bligha686cd82007-10-16 23:30:46 -07001305 group_no, gdp->bg_free_blocks_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306
Martin J. Bligha686cd82007-10-16 23:30:46 -07001307 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308
Martin J. Bligha686cd82007-10-16 23:30:46 -07001309 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1310 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1311 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1312 EXT2_SB(sb)->s_itb_per_group) ||
1313 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1314 EXT2_SB(sb)->s_itb_per_group))
1315 ext2_error(sb, "ext2_new_blocks",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 "Allocating block in system zone - "
Martin J. Bligha686cd82007-10-16 23:30:46 -07001317 "blocks from "E2FSBLK", length %lu",
1318 ret_block, num);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319
Martin J. Bligha686cd82007-10-16 23:30:46 -07001320 performed_allocation = 1;
1321
1322 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1323 ext2_error(sb, "ext2_new_blocks",
1324 "block("E2FSBLK") >= blocks count(%d) - "
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 "block_group = %d, es == %p ", ret_block,
1326 le32_to_cpu(es->s_blocks_count), group_no, es);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001327 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329
Martin J. Bligha686cd82007-10-16 23:30:46 -07001330 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1331 percpu_counter_sub(&sbi->s_freeblocks_counter, num);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332
1333 mark_buffer_dirty(bitmap_bh);
1334 if (sb->s_flags & MS_SYNCHRONOUS)
1335 sync_dirty_buffer(bitmap_bh);
1336
Martin J. Bligha686cd82007-10-16 23:30:46 -07001337 *errp = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 brelse(bitmap_bh);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001339 DQUOT_FREE_BLOCK(inode, *count-num);
1340 *count = num;
1341 return ret_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342
1343io_error:
Martin J. Bligha686cd82007-10-16 23:30:46 -07001344 *errp = -EIO;
1345out:
1346 /*
1347 * Undo the block allocation
1348 */
1349 if (!performed_allocation)
1350 DQUOT_FREE_BLOCK(inode, *count);
1351 brelse(bitmap_bh);
1352 return 0;
1353}
1354
1355ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1356{
1357 unsigned long count = 1;
1358
1359 return ext2_new_blocks(inode, goal, &count, errp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360}
1361
Valerie Henson21730ee2006-06-25 05:48:12 -07001362#ifdef EXT2FS_DEBUG
1363
Philippe De Muyterfebfcf92007-10-16 23:26:15 -07001364static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
Valerie Henson21730ee2006-06-25 05:48:12 -07001365
1366unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
1367{
1368 unsigned int i;
1369 unsigned long sum = 0;
1370
1371 if (!map)
1372 return (0);
1373 for (i = 0; i < numchars; i++)
1374 sum += nibblemap[map->b_data[i] & 0xf] +
1375 nibblemap[(map->b_data[i] >> 4) & 0xf];
1376 return (sum);
1377}
1378
1379#endif /* EXT2FS_DEBUG */
1380
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381unsigned long ext2_count_free_blocks (struct super_block * sb)
1382{
1383 struct ext2_group_desc * desc;
1384 unsigned long desc_count = 0;
1385 int i;
1386#ifdef EXT2FS_DEBUG
1387 unsigned long bitmap_count, x;
1388 struct ext2_super_block *es;
1389
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 es = EXT2_SB(sb)->s_es;
1391 desc_count = 0;
1392 bitmap_count = 0;
1393 desc = NULL;
1394 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1395 struct buffer_head *bitmap_bh;
1396 desc = ext2_get_group_desc (sb, i, NULL);
1397 if (!desc)
1398 continue;
1399 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1400 bitmap_bh = read_block_bitmap(sb, i);
1401 if (!bitmap_bh)
1402 continue;
1403
1404 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1405 printk ("group %d: stored = %d, counted = %lu\n",
1406 i, le16_to_cpu(desc->bg_free_blocks_count), x);
1407 bitmap_count += x;
1408 brelse(bitmap_bh);
1409 }
1410 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1411 (long)le32_to_cpu(es->s_free_blocks_count),
1412 desc_count, bitmap_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 return bitmap_count;
1414#else
1415 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1416 desc = ext2_get_group_desc (sb, i, NULL);
1417 if (!desc)
1418 continue;
1419 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1420 }
1421 return desc_count;
1422#endif
1423}
1424
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425static inline int test_root(int a, int b)
1426{
1427 int num = b;
1428
1429 while (a > num)
1430 num *= b;
1431 return num == a;
1432}
1433
1434static int ext2_group_sparse(int group)
1435{
1436 if (group <= 1)
1437 return 1;
1438 return (test_root(group, 3) || test_root(group, 5) ||
1439 test_root(group, 7));
1440}
1441
1442/**
1443 * ext2_bg_has_super - number of blocks used by the superblock in group
1444 * @sb: superblock for filesystem
1445 * @group: group number to check
1446 *
1447 * Return the number of blocks used by the superblock (primary or backup)
1448 * in this group. Currently this will be only 0 or 1.
1449 */
1450int ext2_bg_has_super(struct super_block *sb, int group)
1451{
1452 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1453 !ext2_group_sparse(group))
1454 return 0;
1455 return 1;
1456}
1457
1458/**
1459 * ext2_bg_num_gdb - number of blocks used by the group table in group
1460 * @sb: superblock for filesystem
1461 * @group: group number to check
1462 *
1463 * Return the number of blocks used by the group descriptor table
1464 * (primary or backup) in this group. In the future there may be a
1465 * different number of descriptor blocks in each group.
1466 */
1467unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1468{
1469 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1470 !ext2_group_sparse(group))
1471 return 0;
1472 return EXT2_SB(sb)->s_gdb_count;
1473}
1474