blob: 2616d0ea5c5c089aaa08007cb9d03e19f5a02258 [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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090016#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/sched.h>
18#include <linux/buffer_head.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080019#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
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
Aneesh Kumar K.Ve6274322007-02-20 13:57:58 -080033 * when a file system is mounted (see ext2_fill_super).
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 */
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
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -080073static 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:
Harvey Harrison605afd62008-04-28 02:16:03 -0700110 ext2_error(sb, __func__,
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -0800111 "Invalid block bitmap - "
112 "block_group = %d, block = %lu",
113 block_group, bitmap_blk);
114 return 0;
115}
116
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117/*
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -0800118 * Read the bitmap for a given block_group,and validate the
119 * bits for block/inode/inode tables are set in the bitmaps
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 *
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;
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -0800128 ext2_fsblk_t bitmap_blk;
129
130 desc = ext2_get_group_desc(sb, block_group, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 if (!desc)
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -0800132 return NULL;
133 bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
134 bh = sb_getblk(sb, bitmap_blk);
135 if (unlikely(!bh)) {
Harvey Harrison605afd62008-04-28 02:16:03 -0700136 ext2_error(sb, __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 "Cannot read block bitmap - "
138 "block_group = %d, block_bitmap = %u",
139 block_group, le32_to_cpu(desc->bg_block_bitmap));
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -0800140 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);
Harvey Harrison605afd62008-04-28 02:16:03 -0700147 ext2_error(sb, __func__,
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -0800148 "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 }
Aneesh Kumar K.V01584fa2008-02-06 01:40:08 -0800153
Aneesh Kumar K.V8b915822008-04-28 02:16:04 -0700154 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 */
Linus Torvalds0b832a42007-11-13 08:07:31 -0800159 return bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160}
161
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162static void release_blocks(struct super_block *sb, int count)
163{
164 if (count) {
165 struct ext2_sb_info *sbi = EXT2_SB(sb);
166
Peter Zijlstraaa0dff22007-10-16 23:25:42 -0700167 percpu_counter_add(&sbi->s_freeblocks_counter, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 }
169}
170
Martin J. Bligha686cd82007-10-16 23:30:46 -0700171static void group_adjust_blocks(struct super_block *sb, int group_no,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 struct ext2_group_desc *desc, struct buffer_head *bh, int count)
173{
174 if (count) {
175 struct ext2_sb_info *sbi = EXT2_SB(sb);
176 unsigned free_blocks;
177
178 spin_lock(sb_bgl_lock(sbi, group_no));
179 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
180 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
181 spin_unlock(sb_bgl_lock(sbi, group_no));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 mark_buffer_dirty(bh);
183 }
184}
185
Martin J. Bligha686cd82007-10-16 23:30:46 -0700186/*
187 * The reservation window structure operations
188 * --------------------------------------------
189 * Operations include:
190 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
191 *
192 * We use a red-black tree to represent per-filesystem reservation
193 * windows.
194 *
195 */
196
197/**
198 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
199 * @rb_root: root of per-filesystem reservation rb tree
200 * @verbose: verbose mode
201 * @fn: function which wishes to dump the reservation map
202 *
203 * If verbose is turned on, it will print the whole block reservation
204 * windows(start, end). Otherwise, it will only print out the "bad" windows,
205 * those windows that overlap with their immediate neighbors.
206 */
207#if 1
208static void __rsv_window_dump(struct rb_root *root, int verbose,
209 const char *fn)
210{
211 struct rb_node *n;
212 struct ext2_reserve_window_node *rsv, *prev;
213 int bad;
214
215restart:
216 n = rb_first(root);
217 bad = 0;
218 prev = NULL;
219
220 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
221 while (n) {
222 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
223 if (verbose)
224 printk("reservation window 0x%p "
225 "start: %lu, end: %lu\n",
226 rsv, rsv->rsv_start, rsv->rsv_end);
227 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
228 printk("Bad reservation %p (start >= end)\n",
229 rsv);
230 bad = 1;
231 }
232 if (prev && prev->rsv_end >= rsv->rsv_start) {
233 printk("Bad reservation %p (prev->end >= start)\n",
234 rsv);
235 bad = 1;
236 }
237 if (bad) {
238 if (!verbose) {
239 printk("Restarting reservation walk in verbose mode\n");
240 verbose = 1;
241 goto restart;
242 }
243 }
244 n = rb_next(n);
245 prev = rsv;
246 }
247 printk("Window map complete.\n");
Julia Lawall2c116192008-04-28 02:16:02 -0700248 BUG_ON(bad);
Martin J. Bligha686cd82007-10-16 23:30:46 -0700249}
250#define rsv_window_dump(root, verbose) \
Harvey Harrison605afd62008-04-28 02:16:03 -0700251 __rsv_window_dump((root), (verbose), __func__)
Martin J. Bligha686cd82007-10-16 23:30:46 -0700252#else
253#define rsv_window_dump(root, verbose) do {} while (0)
254#endif
255
256/**
257 * goal_in_my_reservation()
258 * @rsv: inode's reservation window
259 * @grp_goal: given goal block relative to the allocation block group
260 * @group: the current allocation block group
261 * @sb: filesystem super block
262 *
263 * Test if the given goal block (group relative) is within the file's
264 * own block reservation window range.
265 *
266 * If the reservation window is outside the goal allocation group, return 0;
267 * grp_goal (given goal block) could be -1, which means no specific
268 * goal block. In this case, always return 1.
269 * If the goal block is within the reservation window, return 1;
270 * otherwise, return 0;
271 */
272static int
273goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
274 unsigned int group, struct super_block * sb)
275{
276 ext2_fsblk_t group_first_block, group_last_block;
277
278 group_first_block = ext2_group_first_block_no(sb, group);
279 group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
280
281 if ((rsv->_rsv_start > group_last_block) ||
282 (rsv->_rsv_end < group_first_block))
283 return 0;
284 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
285 || (grp_goal + group_first_block > rsv->_rsv_end)))
286 return 0;
287 return 1;
288}
289
290/**
291 * search_reserve_window()
292 * @rb_root: root of reservation tree
293 * @goal: target allocation block
294 *
295 * Find the reserved window which includes the goal, or the previous one
296 * if the goal is not in any window.
297 * Returns NULL if there are no windows or if all windows start after the goal.
298 */
299static struct ext2_reserve_window_node *
300search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
301{
302 struct rb_node *n = root->rb_node;
303 struct ext2_reserve_window_node *rsv;
304
305 if (!n)
306 return NULL;
307
308 do {
309 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
310
311 if (goal < rsv->rsv_start)
312 n = n->rb_left;
313 else if (goal > rsv->rsv_end)
314 n = n->rb_right;
315 else
316 return rsv;
317 } while (n);
318 /*
319 * We've fallen off the end of the tree: the goal wasn't inside
320 * any particular node. OK, the previous node must be to one
321 * side of the interval containing the goal. If it's the RHS,
322 * we need to back up one.
323 */
324 if (rsv->rsv_start > goal) {
325 n = rb_prev(&rsv->rsv_node);
326 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
327 }
328 return rsv;
329}
330
331/*
332 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
333 * @sb: super block
334 * @rsv: reservation window to add
335 *
336 * Must be called with rsv_lock held.
337 */
338void ext2_rsv_window_add(struct super_block *sb,
339 struct ext2_reserve_window_node *rsv)
340{
341 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
342 struct rb_node *node = &rsv->rsv_node;
343 ext2_fsblk_t start = rsv->rsv_start;
344
345 struct rb_node ** p = &root->rb_node;
346 struct rb_node * parent = NULL;
347 struct ext2_reserve_window_node *this;
348
349 while (*p)
350 {
351 parent = *p;
352 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
353
354 if (start < this->rsv_start)
355 p = &(*p)->rb_left;
356 else if (start > this->rsv_end)
357 p = &(*p)->rb_right;
358 else {
359 rsv_window_dump(root, 1);
360 BUG();
361 }
362 }
363
364 rb_link_node(node, parent, p);
365 rb_insert_color(node, root);
366}
367
368/**
369 * rsv_window_remove() -- unlink a window from the reservation rb tree
370 * @sb: super block
371 * @rsv: reservation window to remove
372 *
373 * Mark the block reservation window as not allocated, and unlink it
374 * from the filesystem reservation window rb tree. Must be called with
375 * rsv_lock held.
376 */
377static void rsv_window_remove(struct super_block *sb,
378 struct ext2_reserve_window_node *rsv)
379{
380 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
381 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
382 rsv->rsv_alloc_hit = 0;
383 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
384}
385
386/*
387 * rsv_is_empty() -- Check if the reservation window is allocated.
388 * @rsv: given reservation window to check
389 *
390 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
391 */
392static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
393{
394 /* a valid reservation end block could not be 0 */
395 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
396}
397
398/**
399 * ext2_init_block_alloc_info()
400 * @inode: file inode structure
401 *
402 * Allocate and initialize the reservation window structure, and
403 * link the window to the ext2 inode structure at last
404 *
405 * The reservation window structure is only dynamically allocated
406 * and linked to ext2 inode the first time the open file
407 * needs a new block. So, before every ext2_new_block(s) call, for
408 * regular files, we should check whether the reservation window
409 * structure exists or not. In the latter case, this function is called.
410 * Fail to do so will result in block reservation being turned off for that
411 * open file.
412 *
413 * This function is called from ext2_get_blocks_handle(), also called
414 * when setting the reservation window size through ioctl before the file
415 * is open for write (needs block allocation).
416 *
417 * Needs truncate_mutex protection prior to calling this function.
418 */
419void ext2_init_block_alloc_info(struct inode *inode)
420{
421 struct ext2_inode_info *ei = EXT2_I(inode);
Julia Lawall6e3d6ca2011-08-04 12:29:32 +0200422 struct ext2_block_alloc_info *block_i;
Martin J. Bligha686cd82007-10-16 23:30:46 -0700423 struct super_block *sb = inode->i_sb;
424
425 block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
426 if (block_i) {
427 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
428
429 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
430 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
431
432 /*
433 * if filesystem is mounted with NORESERVATION, the goal
434 * reservation window size is set to zero to indicate
435 * block reservation is off
436 */
437 if (!test_opt(sb, RESERVATION))
438 rsv->rsv_goal_size = 0;
439 else
440 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
441 rsv->rsv_alloc_hit = 0;
442 block_i->last_alloc_logical_block = 0;
443 block_i->last_alloc_physical_block = 0;
444 }
445 ei->i_block_alloc_info = block_i;
446}
447
448/**
449 * ext2_discard_reservation()
450 * @inode: inode
451 *
452 * Discard(free) block reservation window on last file close, or truncate
453 * or at last iput().
454 *
455 * It is being called in three cases:
456 * ext2_release_file(): last writer closes the file
457 * ext2_clear_inode(): last iput(), when nobody links to this file.
458 * ext2_truncate(): when the block indirect map is about to change.
459 */
460void ext2_discard_reservation(struct inode *inode)
461{
462 struct ext2_inode_info *ei = EXT2_I(inode);
463 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
464 struct ext2_reserve_window_node *rsv;
465 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
466
467 if (!block_i)
468 return;
469
470 rsv = &block_i->rsv_window_node;
471 if (!rsv_is_empty(&rsv->rsv_window)) {
472 spin_lock(rsv_lock);
473 if (!rsv_is_empty(&rsv->rsv_window))
474 rsv_window_remove(inode->i_sb, rsv);
475 spin_unlock(rsv_lock);
476 }
477}
478
479/**
Wang Sheng-Hui03248762012-05-18 15:04:45 +0800480 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks
Martin J. Bligha686cd82007-10-16 23:30:46 -0700481 * @inode: inode
Anatol Pomozov4907cb72012-09-01 10:31:09 -0700482 * @block: start physical block to free
Martin J. Bligha686cd82007-10-16 23:30:46 -0700483 * @count: number of blocks to free
484 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485void ext2_free_blocks (struct inode * inode, unsigned long block,
486 unsigned long count)
487{
488 struct buffer_head *bitmap_bh = NULL;
489 struct buffer_head * bh2;
490 unsigned long block_group;
491 unsigned long bit;
492 unsigned long i;
493 unsigned long overflow;
494 struct super_block * sb = inode->i_sb;
495 struct ext2_sb_info * sbi = EXT2_SB(sb);
496 struct ext2_group_desc * desc;
497 struct ext2_super_block * es = sbi->s_es;
498 unsigned freed = 0, group_freed;
499
500 if (block < le32_to_cpu(es->s_first_data_block) ||
501 block + count < block ||
502 block + count > le32_to_cpu(es->s_blocks_count)) {
503 ext2_error (sb, "ext2_free_blocks",
504 "Freeing blocks not in datazone - "
505 "block = %lu, count = %lu", block, count);
506 goto error_return;
507 }
508
509 ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
510
511do_more:
512 overflow = 0;
513 block_group = (block - le32_to_cpu(es->s_first_data_block)) /
514 EXT2_BLOCKS_PER_GROUP(sb);
515 bit = (block - le32_to_cpu(es->s_first_data_block)) %
516 EXT2_BLOCKS_PER_GROUP(sb);
517 /*
518 * Check to see if we are freeing blocks across a group
519 * boundary.
520 */
521 if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
522 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
523 count -= overflow;
524 }
525 brelse(bitmap_bh);
526 bitmap_bh = read_block_bitmap(sb, block_group);
527 if (!bitmap_bh)
528 goto error_return;
529
530 desc = ext2_get_group_desc (sb, block_group, &bh2);
531 if (!desc)
532 goto error_return;
533
534 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
535 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
536 in_range (block, le32_to_cpu(desc->bg_inode_table),
537 sbi->s_itb_per_group) ||
538 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -0800539 sbi->s_itb_per_group)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 ext2_error (sb, "ext2_free_blocks",
541 "Freeing blocks in system zones - "
542 "Block = %lu, count = %lu",
543 block, count);
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -0800544 goto error_return;
545 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546
547 for (i = 0, group_freed = 0; i < count; i++) {
548 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
549 bit + i, bitmap_bh->b_data)) {
Harvey Harrison605afd62008-04-28 02:16:03 -0700550 ext2_error(sb, __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551 "bit already cleared for block %lu", block + i);
552 } else {
553 group_freed++;
554 }
555 }
556
557 mark_buffer_dirty(bitmap_bh);
558 if (sb->s_flags & MS_SYNCHRONOUS)
559 sync_dirty_buffer(bitmap_bh);
560
Martin J. Bligha686cd82007-10-16 23:30:46 -0700561 group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 freed += group_freed;
563
564 if (overflow) {
565 block += count;
566 count = overflow;
567 goto do_more;
568 }
569error_return:
570 brelse(bitmap_bh);
571 release_blocks(sb, freed);
Al Viro38897172010-07-22 01:13:36 +0400572 dquot_free_block_nodirty(inode, freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573}
574
Martin J. Bligha686cd82007-10-16 23:30:46 -0700575/**
576 * bitmap_search_next_usable_block()
577 * @start: the starting block (group relative) of the search
578 * @bh: bufferhead contains the block group bitmap
579 * @maxblocks: the ending block (group relative) of the reservation
580 *
581 * The bitmap search --- search forward through the actual bitmap on disk until
582 * we find a bit free.
583 */
584static ext2_grpblk_t
585bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
586 ext2_grpblk_t maxblocks)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587{
Martin J. Bligha686cd82007-10-16 23:30:46 -0700588 ext2_grpblk_t next;
589
590 next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
591 if (next >= maxblocks)
592 return -1;
593 return next;
594}
595
596/**
597 * find_next_usable_block()
598 * @start: the starting block (group relative) to find next
599 * allocatable block in bitmap.
600 * @bh: bufferhead contains the block group bitmap
601 * @maxblocks: the ending block (group relative) for the search
602 *
603 * Find an allocatable block in a bitmap. We perform the "most
604 * appropriate allocation" algorithm of looking for a free block near
605 * the initial goal; then for a free byte somewhere in the bitmap;
606 * then for any free bit in the bitmap.
607 */
608static ext2_grpblk_t
609find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
610{
611 ext2_grpblk_t here, next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 char *p, *r;
613
Martin J. Bligha686cd82007-10-16 23:30:46 -0700614 if (start > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 /*
616 * The goal was occupied; search forward for a free
617 * block within the next XX blocks.
618 *
619 * end_goal is more or less random, but it has to be
620 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
621 * next 64-bit boundary is simple..
622 */
Martin J. Bligha686cd82007-10-16 23:30:46 -0700623 ext2_grpblk_t end_goal = (start + 63) & ~63;
624 if (end_goal > maxblocks)
625 end_goal = maxblocks;
626 here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
627 if (here < end_goal)
628 return here;
629 ext2_debug("Bit not found near goal\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 }
631
Martin J. Bligha686cd82007-10-16 23:30:46 -0700632 here = start;
633 if (here < 0)
634 here = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635
Martin J. Bligha686cd82007-10-16 23:30:46 -0700636 p = ((char *)bh->b_data) + (here >> 3);
637 r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
638 next = (r - ((char *)bh->b_data)) << 3;
639
640 if (next < maxblocks && next >= here)
641 return next;
642
643 here = bitmap_search_next_usable_block(here, bh, maxblocks);
644 return here;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645}
646
Namhyung Kim26f78b72010-09-26 15:31:00 +0900647/**
Martin J. Bligha686cd82007-10-16 23:30:46 -0700648 * ext2_try_to_allocate()
649 * @sb: superblock
Martin J. Bligha686cd82007-10-16 23:30:46 -0700650 * @group: given allocation block group
651 * @bitmap_bh: bufferhead holds the block bitmap
652 * @grp_goal: given target block within the group
653 * @count: target number of blocks to allocate
654 * @my_rsv: reservation window
655 *
656 * Attempt to allocate blocks within a give range. Set the range of allocation
657 * first, then find the first free bit(s) from the bitmap (within the range),
658 * and at last, allocate the blocks by claiming the found free bit as allocated.
659 *
660 * To set the range of this allocation:
661 * if there is a reservation window, only try to allocate block(s)
662 * from the file's own reservation window;
663 * Otherwise, the allocation range starts from the give goal block,
664 * ends at the block group's last block.
665 *
666 * If we failed to allocate the desired block then we may end up crossing to a
667 * new bitmap.
668 */
669static int
670ext2_try_to_allocate(struct super_block *sb, int group,
671 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
672 unsigned long *count,
673 struct ext2_reserve_window *my_rsv)
674{
675 ext2_fsblk_t group_first_block;
676 ext2_grpblk_t start, end;
677 unsigned long num = 0;
678
679 /* we do allocation within the reservation window if we have a window */
680 if (my_rsv) {
681 group_first_block = ext2_group_first_block_no(sb, group);
682 if (my_rsv->_rsv_start >= group_first_block)
683 start = my_rsv->_rsv_start - group_first_block;
684 else
685 /* reservation window cross group boundary */
686 start = 0;
687 end = my_rsv->_rsv_end - group_first_block + 1;
688 if (end > EXT2_BLOCKS_PER_GROUP(sb))
689 /* reservation window crosses group boundary */
690 end = EXT2_BLOCKS_PER_GROUP(sb);
691 if ((start <= grp_goal) && (grp_goal < end))
692 start = grp_goal;
693 else
694 grp_goal = -1;
695 } else {
696 if (grp_goal > 0)
697 start = grp_goal;
698 else
699 start = 0;
700 end = EXT2_BLOCKS_PER_GROUP(sb);
701 }
702
703 BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
704
705repeat:
706 if (grp_goal < 0) {
707 grp_goal = find_next_usable_block(start, bitmap_bh, end);
708 if (grp_goal < 0)
709 goto fail_access;
710 if (!my_rsv) {
711 int i;
712
713 for (i = 0; i < 7 && grp_goal > start &&
714 !ext2_test_bit(grp_goal - 1,
715 bitmap_bh->b_data);
716 i++, grp_goal--)
717 ;
718 }
719 }
720 start = grp_goal;
721
722 if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
723 bitmap_bh->b_data)) {
724 /*
725 * The block was allocated by another thread, or it was
726 * allocated and then freed by another thread
727 */
728 start++;
729 grp_goal++;
730 if (start >= end)
731 goto fail_access;
732 goto repeat;
733 }
734 num++;
735 grp_goal++;
736 while (num < *count && grp_goal < end
737 && !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
738 grp_goal, bitmap_bh->b_data)) {
739 num++;
740 grp_goal++;
741 }
742 *count = num;
743 return grp_goal - num;
744fail_access:
745 *count = num;
746 return -1;
747}
748
749/**
750 * find_next_reservable_window():
751 * find a reservable space within the given range.
752 * It does not allocate the reservation window for now:
753 * alloc_new_reservation() will do the work later.
754 *
755 * @search_head: the head of the searching list;
756 * This is not necessarily the list head of the whole filesystem
757 *
758 * We have both head and start_block to assist the search
759 * for the reservable space. The list starts from head,
760 * but we will shift to the place where start_block is,
761 * then start from there, when looking for a reservable space.
762 *
763 * @size: the target new reservation window size
764 *
765 * @group_first_block: the first block we consider to start
766 * the real search from
767 *
768 * @last_block:
769 * the maximum block number that our goal reservable space
770 * could start from. This is normally the last block in this
771 * group. The search will end when we found the start of next
772 * possible reservable space is out of this boundary.
773 * This could handle the cross boundary reservation window
774 * request.
775 *
776 * basically we search from the given range, rather than the whole
777 * reservation double linked list, (start_block, last_block)
778 * to find a free region that is of my size and has not
779 * been reserved.
780 *
781 */
782static int find_next_reservable_window(
783 struct ext2_reserve_window_node *search_head,
784 struct ext2_reserve_window_node *my_rsv,
785 struct super_block * sb,
786 ext2_fsblk_t start_block,
787 ext2_fsblk_t last_block)
788{
789 struct rb_node *next;
790 struct ext2_reserve_window_node *rsv, *prev;
791 ext2_fsblk_t cur;
792 int size = my_rsv->rsv_goal_size;
793
794 /* TODO: make the start of the reservation window byte-aligned */
795 /* cur = *start_block & ~7;*/
796 cur = start_block;
797 rsv = search_head;
798 if (!rsv)
799 return -1;
800
801 while (1) {
802 if (cur <= rsv->rsv_end)
803 cur = rsv->rsv_end + 1;
804
805 /* TODO?
806 * in the case we could not find a reservable space
807 * that is what is expected, during the re-search, we could
808 * remember what's the largest reservable space we could have
809 * and return that one.
810 *
811 * For now it will fail if we could not find the reservable
812 * space with expected-size (or more)...
813 */
814 if (cur > last_block)
815 return -1; /* fail */
816
817 prev = rsv;
818 next = rb_next(&rsv->rsv_node);
819 rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
820
821 /*
822 * Reached the last reservation, we can just append to the
823 * previous one.
824 */
825 if (!next)
826 break;
827
828 if (cur + size <= rsv->rsv_start) {
829 /*
830 * Found a reserveable space big enough. We could
831 * have a reservation across the group boundary here
832 */
833 break;
834 }
835 }
836 /*
837 * we come here either :
838 * when we reach the end of the whole list,
839 * and there is empty reservable space after last entry in the list.
840 * append it to the end of the list.
841 *
842 * or we found one reservable space in the middle of the list,
843 * return the reservation window that we could append to.
844 * succeed.
845 */
846
847 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
848 rsv_window_remove(sb, my_rsv);
849
850 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300851 * Let's book the whole available window for now. We will check the
Martin J. Bligha686cd82007-10-16 23:30:46 -0700852 * disk bitmap later and then, if there are free blocks then we adjust
853 * the window size if it's larger than requested.
854 * Otherwise, we will remove this node from the tree next time
855 * call find_next_reservable_window.
856 */
857 my_rsv->rsv_start = cur;
858 my_rsv->rsv_end = cur + size - 1;
859 my_rsv->rsv_alloc_hit = 0;
860
861 if (prev != my_rsv)
862 ext2_rsv_window_add(sb, my_rsv);
863
864 return 0;
865}
866
867/**
868 * alloc_new_reservation()--allocate a new reservation window
869 *
870 * To make a new reservation, we search part of the filesystem
871 * reservation list (the list that inside the group). We try to
872 * allocate a new reservation window near the allocation goal,
873 * or the beginning of the group, if there is no goal.
874 *
875 * We first find a reservable space after the goal, then from
876 * there, we check the bitmap for the first free block after
877 * it. If there is no free block until the end of group, then the
878 * whole group is full, we failed. Otherwise, check if the free
879 * block is inside the expected reservable space, if so, we
880 * succeed.
881 * If the first free block is outside the reservable space, then
882 * start from the first free block, we search for next available
883 * space, and go on.
884 *
885 * on succeed, a new reservation will be found and inserted into the list
886 * It contains at least one free block, and it does not overlap with other
887 * reservation windows.
888 *
889 * failed: we failed to find a reservation window in this group
890 *
891 * @rsv: the reservation
892 *
893 * @grp_goal: The goal (group-relative). It is where the search for a
894 * free reservable space should start from.
895 * if we have a goal(goal >0 ), then start from there,
896 * no goal(goal = -1), we start from the first block
897 * of the group.
898 *
899 * @sb: the super block
900 * @group: the group we are trying to allocate in
901 * @bitmap_bh: the block group block bitmap
902 *
903 */
904static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
905 ext2_grpblk_t grp_goal, struct super_block *sb,
906 unsigned int group, struct buffer_head *bitmap_bh)
907{
908 struct ext2_reserve_window_node *search_head;
909 ext2_fsblk_t group_first_block, group_end_block, start_block;
910 ext2_grpblk_t first_free_block;
911 struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
912 unsigned long size;
913 int ret;
914 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
915
916 group_first_block = ext2_group_first_block_no(sb, group);
917 group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
918
919 if (grp_goal < 0)
920 start_block = group_first_block;
921 else
922 start_block = grp_goal + group_first_block;
923
924 size = my_rsv->rsv_goal_size;
925
926 if (!rsv_is_empty(&my_rsv->rsv_window)) {
927 /*
928 * if the old reservation is cross group boundary
929 * and if the goal is inside the old reservation window,
930 * we will come here when we just failed to allocate from
931 * the first part of the window. We still have another part
932 * that belongs to the next group. In this case, there is no
933 * point to discard our window and try to allocate a new one
934 * in this group(which will fail). we should
935 * keep the reservation window, just simply move on.
936 *
937 * Maybe we could shift the start block of the reservation
938 * window to the first block of next group.
939 */
940
941 if ((my_rsv->rsv_start <= group_end_block) &&
942 (my_rsv->rsv_end > group_end_block) &&
943 (start_block >= my_rsv->rsv_start))
944 return -1;
945
946 if ((my_rsv->rsv_alloc_hit >
947 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
948 /*
949 * if the previously allocation hit ratio is
950 * greater than 1/2, then we double the size of
951 * the reservation window the next time,
952 * otherwise we keep the same size window
953 */
954 size = size * 2;
955 if (size > EXT2_MAX_RESERVE_BLOCKS)
956 size = EXT2_MAX_RESERVE_BLOCKS;
957 my_rsv->rsv_goal_size= size;
958 }
959 }
960
961 spin_lock(rsv_lock);
962 /*
963 * shift the search start to the window near the goal block
964 */
965 search_head = search_reserve_window(fs_rsv_root, start_block);
966
967 /*
968 * find_next_reservable_window() simply finds a reservable window
969 * inside the given range(start_block, group_end_block).
970 *
971 * To make sure the reservation window has a free bit inside it, we
972 * need to check the bitmap after we found a reservable window.
973 */
974retry:
975 ret = find_next_reservable_window(search_head, my_rsv, sb,
976 start_block, group_end_block);
977
978 if (ret == -1) {
979 if (!rsv_is_empty(&my_rsv->rsv_window))
980 rsv_window_remove(sb, my_rsv);
981 spin_unlock(rsv_lock);
982 return -1;
983 }
984
985 /*
986 * On success, find_next_reservable_window() returns the
987 * reservation window where there is a reservable space after it.
988 * Before we reserve this reservable space, we need
989 * to make sure there is at least a free block inside this region.
990 *
991 * Search the first free bit on the block bitmap. Search starts from
992 * the start block of the reservable space we just found.
993 */
994 spin_unlock(rsv_lock);
995 first_free_block = bitmap_search_next_usable_block(
996 my_rsv->rsv_start - group_first_block,
997 bitmap_bh, group_end_block - group_first_block + 1);
998
999 if (first_free_block < 0) {
1000 /*
1001 * no free block left on the bitmap, no point
1002 * to reserve the space. return failed.
1003 */
1004 spin_lock(rsv_lock);
1005 if (!rsv_is_empty(&my_rsv->rsv_window))
1006 rsv_window_remove(sb, my_rsv);
1007 spin_unlock(rsv_lock);
1008 return -1; /* failed */
1009 }
1010
1011 start_block = first_free_block + group_first_block;
1012 /*
1013 * check if the first free block is within the
1014 * free space we just reserved
1015 */
1016 if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1017 return 0; /* success */
1018 /*
1019 * if the first free bit we found is out of the reservable space
1020 * continue search for next reservable space,
1021 * start from where the free block is,
1022 * we also shift the list head to where we stopped last time
1023 */
1024 search_head = my_rsv;
1025 spin_lock(rsv_lock);
1026 goto retry;
1027}
1028
1029/**
1030 * try_to_extend_reservation()
1031 * @my_rsv: given reservation window
1032 * @sb: super block
1033 * @size: the delta to extend
1034 *
1035 * Attempt to expand the reservation window large enough to have
1036 * required number of free blocks
1037 *
1038 * Since ext2_try_to_allocate() will always allocate blocks within
1039 * the reservation window range, if the window size is too small,
1040 * multiple blocks allocation has to stop at the end of the reservation
1041 * window. To make this more efficient, given the total number of
1042 * blocks needed and the current size of the window, we try to
1043 * expand the reservation window size if necessary on a best-effort
1044 * basis before ext2_new_blocks() tries to allocate blocks.
1045 */
1046static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1047 struct super_block *sb, int size)
1048{
1049 struct ext2_reserve_window_node *next_rsv;
1050 struct rb_node *next;
1051 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1052
1053 if (!spin_trylock(rsv_lock))
1054 return;
1055
1056 next = rb_next(&my_rsv->rsv_node);
1057
1058 if (!next)
1059 my_rsv->rsv_end += size;
1060 else {
1061 next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1062
1063 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1064 my_rsv->rsv_end += size;
1065 else
1066 my_rsv->rsv_end = next_rsv->rsv_start - 1;
1067 }
1068 spin_unlock(rsv_lock);
1069}
1070
1071/**
1072 * ext2_try_to_allocate_with_rsv()
1073 * @sb: superblock
1074 * @group: given allocation block group
1075 * @bitmap_bh: bufferhead holds the block bitmap
1076 * @grp_goal: given target block within the group
1077 * @count: target number of blocks to allocate
1078 * @my_rsv: reservation window
1079 *
1080 * This is the main function used to allocate a new block and its reservation
1081 * window.
1082 *
1083 * Each time when a new block allocation is need, first try to allocate from
1084 * its own reservation. If it does not have a reservation window, instead of
1085 * looking for a free bit on bitmap first, then look up the reservation list to
1086 * see if it is inside somebody else's reservation window, we try to allocate a
1087 * reservation window for it starting from the goal first. Then do the block
1088 * allocation within the reservation window.
1089 *
1090 * This will avoid keeping on searching the reservation list again and
1091 * again when somebody is looking for a free block (without
1092 * reservation), and there are lots of free blocks, but they are all
1093 * being reserved.
1094 *
1095 * We use a red-black tree for the per-filesystem reservation list.
1096 */
1097static ext2_grpblk_t
1098ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1099 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1100 struct ext2_reserve_window_node * my_rsv,
1101 unsigned long *count)
1102{
1103 ext2_fsblk_t group_first_block, group_last_block;
1104 ext2_grpblk_t ret = 0;
1105 unsigned long num = *count;
1106
1107 /*
1108 * we don't deal with reservation when
1109 * filesystem is mounted without reservation
1110 * or the file is not a regular file
1111 * or last attempt to allocate a block with reservation turned on failed
1112 */
1113 if (my_rsv == NULL) {
1114 return ext2_try_to_allocate(sb, group, bitmap_bh,
1115 grp_goal, count, NULL);
1116 }
1117 /*
1118 * grp_goal is a group relative block number (if there is a goal)
1119 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1120 * first block is a filesystem wide block number
1121 * first block is the block number of the first block in this group
1122 */
1123 group_first_block = ext2_group_first_block_no(sb, group);
1124 group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
1125
1126 /*
1127 * Basically we will allocate a new block from inode's reservation
1128 * window.
1129 *
1130 * We need to allocate a new reservation window, if:
1131 * a) inode does not have a reservation window; or
1132 * b) last attempt to allocate a block from existing reservation
1133 * failed; or
1134 * c) we come here with a goal and with a reservation window
1135 *
1136 * We do not need to allocate a new reservation window if we come here
1137 * at the beginning with a goal and the goal is inside the window, or
1138 * we don't have a goal but already have a reservation window.
1139 * then we could go to allocate from the reservation window directly.
1140 */
1141 while (1) {
1142 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1143 !goal_in_my_reservation(&my_rsv->rsv_window,
1144 grp_goal, group, sb)) {
1145 if (my_rsv->rsv_goal_size < *count)
1146 my_rsv->rsv_goal_size = *count;
1147 ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1148 group, bitmap_bh);
1149 if (ret < 0)
1150 break; /* failed */
1151
1152 if (!goal_in_my_reservation(&my_rsv->rsv_window,
1153 grp_goal, group, sb))
1154 grp_goal = -1;
1155 } else if (grp_goal >= 0) {
1156 int curr = my_rsv->rsv_end -
1157 (grp_goal + group_first_block) + 1;
1158
1159 if (curr < *count)
1160 try_to_extend_reservation(my_rsv, sb,
1161 *count - curr);
1162 }
1163
1164 if ((my_rsv->rsv_start > group_last_block) ||
1165 (my_rsv->rsv_end < group_first_block)) {
1166 rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1167 BUG();
1168 }
1169 ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1170 &num, &my_rsv->rsv_window);
1171 if (ret >= 0) {
1172 my_rsv->rsv_alloc_hit += num;
1173 *count = num;
1174 break; /* succeed */
1175 }
1176 num = *count;
1177 }
1178 return ret;
1179}
1180
1181/**
1182 * ext2_has_free_blocks()
1183 * @sbi: in-core super block structure.
1184 *
1185 * Check if filesystem has at least 1 free block available for allocation.
1186 */
1187static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1188{
1189 ext2_fsblk_t free_blocks, root_blocks;
1190
1191 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1192 root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1193 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
Eric W. Biedermanb8a9f9e2012-02-07 15:39:12 -08001194 !uid_eq(sbi->s_resuid, current_fsuid()) &&
1195 (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1196 !in_group_p (sbi->s_resgid))) {
Martin J. Bligha686cd82007-10-16 23:30:46 -07001197 return 0;
1198 }
1199 return 1;
1200}
1201
1202/*
1203 * ext2_new_blocks() -- core block(s) allocation function
1204 * @inode: file inode
1205 * @goal: given target block(filesystem wide)
1206 * @count: target number of blocks to allocate
1207 * @errp: error code
1208 *
1209 * ext2_new_blocks uses a goal block to assist allocation. If the goal is
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 * free, or there is a free block within 32 blocks of the goal, that block
1211 * is allocated. Otherwise a forward search is made for a free block; within
1212 * each block group the search first looks for an entire free byte in the block
1213 * bitmap, and then for any free bit if that fails.
1214 * This function also updates quota and i_blocks field.
1215 */
Martin J. Bligha686cd82007-10-16 23:30:46 -07001216ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1217 unsigned long *count, int *errp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218{
1219 struct buffer_head *bitmap_bh = NULL;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001220 struct buffer_head *gdp_bh;
1221 int group_no;
1222 int goal_group;
1223 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1224 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1225 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1226 int bgi; /* blockgroup iteration index */
1227 int performed_allocation = 0;
1228 ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1229 struct super_block *sb;
1230 struct ext2_group_desc *gdp;
1231 struct ext2_super_block *es;
1232 struct ext2_sb_info *sbi;
1233 struct ext2_reserve_window_node *my_rsv = NULL;
1234 struct ext2_block_alloc_info *block_i;
1235 unsigned short windowsz = 0;
1236 unsigned long ngroups;
1237 unsigned long num = *count;
Christoph Hellwig5dd40562010-03-03 09:05:00 -05001238 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239
Martin J. Bligha686cd82007-10-16 23:30:46 -07001240 *errp = -ENOSPC;
1241 sb = inode->i_sb;
1242 if (!sb) {
1243 printk("ext2_new_blocks: nonexistent device");
1244 return 0;
1245 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246
Martin J. Bligha686cd82007-10-16 23:30:46 -07001247 /*
1248 * Check quota for allocation of this block.
1249 */
Christoph Hellwig5dd40562010-03-03 09:05:00 -05001250 ret = dquot_alloc_block(inode, num);
1251 if (ret) {
1252 *errp = ret;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001253 return 0;
1254 }
1255
1256 sbi = EXT2_SB(sb);
1257 es = EXT2_SB(sb)->s_es;
1258 ext2_debug("goal=%lu.\n", goal);
1259 /*
1260 * Allocate a block from reservation only when
1261 * filesystem is mounted with reservation(default,-o reservation), and
1262 * it's a regular file, and
1263 * the desired window size is greater than 0 (One could use ioctl
1264 * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1265 * reservation on that particular file)
1266 */
1267 block_i = EXT2_I(inode)->i_block_alloc_info;
1268 if (block_i) {
1269 windowsz = block_i->rsv_window_node.rsv_goal_size;
1270 if (windowsz > 0)
1271 my_rsv = &block_i->rsv_window_node;
1272 }
1273
1274 if (!ext2_has_free_blocks(sbi)) {
1275 *errp = -ENOSPC;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 goto out;
1277 }
1278
Martin J. Bligha686cd82007-10-16 23:30:46 -07001279 /*
1280 * First, test whether the goal block is free.
1281 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 if (goal < le32_to_cpu(es->s_first_data_block) ||
1283 goal >= le32_to_cpu(es->s_blocks_count))
1284 goal = le32_to_cpu(es->s_first_data_block);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001285 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1286 EXT2_BLOCKS_PER_GROUP(sb);
1287 goal_group = group_no;
1288retry_alloc:
1289 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1290 if (!gdp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291 goto io_error;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001292
1293 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1294 /*
1295 * if there is not enough free blocks to make a new resevation
1296 * turn off reservation for this allocation
1297 */
1298 if (my_rsv && (free_blocks < windowsz)
Mingming Caod707d312008-10-15 22:04:01 -07001299 && (free_blocks > 0)
Martin J. Bligha686cd82007-10-16 23:30:46 -07001300 && (rsv_is_empty(&my_rsv->rsv_window)))
1301 my_rsv = NULL;
1302
1303 if (free_blocks > 0) {
1304 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1305 EXT2_BLOCKS_PER_GROUP(sb));
1306 bitmap_bh = read_block_bitmap(sb, group_no);
1307 if (!bitmap_bh)
1308 goto io_error;
1309 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1310 bitmap_bh, grp_target_blk,
1311 my_rsv, &num);
1312 if (grp_alloc_blk >= 0)
1313 goto allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314 }
1315
Martin J. Bligha686cd82007-10-16 23:30:46 -07001316 ngroups = EXT2_SB(sb)->s_groups_count;
1317 smp_rmb();
1318
1319 /*
Akinobu Mita144704e2008-02-06 01:40:15 -08001320 * Now search the rest of the groups. We assume that
1321 * group_no and gdp correctly point to the last group visited.
Martin J. Bligha686cd82007-10-16 23:30:46 -07001322 */
1323 for (bgi = 0; bgi < ngroups; bgi++) {
1324 group_no++;
1325 if (group_no >= ngroups)
1326 group_no = 0;
1327 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1328 if (!gdp)
1329 goto io_error;
1330
1331 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1332 /*
Jan Kara46891532010-03-29 13:55:39 +02001333 * skip this group (and avoid loading bitmap) if there
1334 * are no free blocks
1335 */
1336 if (!free_blocks)
1337 continue;
1338 /*
Martin J. Bligha686cd82007-10-16 23:30:46 -07001339 * skip this group if the number of
1340 * free blocks is less than half of the reservation
1341 * window size.
1342 */
Mingming Caod707d312008-10-15 22:04:01 -07001343 if (my_rsv && (free_blocks <= (windowsz/2)))
Martin J. Bligha686cd82007-10-16 23:30:46 -07001344 continue;
1345
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 brelse(bitmap_bh);
1347 bitmap_bh = read_block_bitmap(sb, group_no);
1348 if (!bitmap_bh)
1349 goto io_error;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001350 /*
1351 * try to allocate block(s) from this group, without a goal(-1).
1352 */
1353 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1354 bitmap_bh, -1, my_rsv, &num);
1355 if (grp_alloc_blk >= 0)
1356 goto allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001359 * We may end up a bogus earlier ENOSPC error due to
Martin J. Bligha686cd82007-10-16 23:30:46 -07001360 * filesystem is "full" of reservations, but
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001361 * there maybe indeed free blocks available on disk
Martin J. Bligha686cd82007-10-16 23:30:46 -07001362 * In this case, we just forget about the reservations
1363 * just do block allocation as without reservations.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 */
Martin J. Bligha686cd82007-10-16 23:30:46 -07001365 if (my_rsv) {
1366 my_rsv = NULL;
1367 windowsz = 0;
1368 group_no = goal_group;
1369 goto retry_alloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 }
Martin J. Bligha686cd82007-10-16 23:30:46 -07001371 /* No space left on the device */
1372 *errp = -ENOSPC;
1373 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374
Martin J. Bligha686cd82007-10-16 23:30:46 -07001375allocated:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 ext2_debug("using block group %d(%d)\n",
Martin J. Bligha686cd82007-10-16 23:30:46 -07001378 group_no, gdp->bg_free_blocks_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
Martin J. Bligha686cd82007-10-16 23:30:46 -07001380 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381
Martin J. Bligha686cd82007-10-16 23:30:46 -07001382 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1383 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1384 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1385 EXT2_SB(sb)->s_itb_per_group) ||
1386 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -08001387 EXT2_SB(sb)->s_itb_per_group)) {
Martin J. Bligha686cd82007-10-16 23:30:46 -07001388 ext2_error(sb, "ext2_new_blocks",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 "Allocating block in system zone - "
Martin J. Bligha686cd82007-10-16 23:30:46 -07001390 "blocks from "E2FSBLK", length %lu",
1391 ret_block, num);
Aneesh Kumar K.V8b915822008-04-28 02:16:04 -07001392 /*
1393 * ext2_try_to_allocate marked the blocks we allocated as in
1394 * use. So we may want to selectively mark some of the blocks
1395 * as free
1396 */
1397 goto retry_alloc;
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -08001398 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
Martin J. Bligha686cd82007-10-16 23:30:46 -07001400 performed_allocation = 1;
1401
1402 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1403 ext2_error(sb, "ext2_new_blocks",
1404 "block("E2FSBLK") >= blocks count(%d) - "
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 "block_group = %d, es == %p ", ret_block,
1406 le32_to_cpu(es->s_blocks_count), group_no, es);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001407 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409
Martin J. Bligha686cd82007-10-16 23:30:46 -07001410 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1411 percpu_counter_sub(&sbi->s_freeblocks_counter, num);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412
1413 mark_buffer_dirty(bitmap_bh);
1414 if (sb->s_flags & MS_SYNCHRONOUS)
1415 sync_dirty_buffer(bitmap_bh);
1416
Martin J. Bligha686cd82007-10-16 23:30:46 -07001417 *errp = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 brelse(bitmap_bh);
Al Viro38897172010-07-22 01:13:36 +04001419 dquot_free_block_nodirty(inode, *count-num);
1420 mark_inode_dirty(inode);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001421 *count = num;
1422 return ret_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423
1424io_error:
Martin J. Bligha686cd82007-10-16 23:30:46 -07001425 *errp = -EIO;
1426out:
1427 /*
1428 * Undo the block allocation
1429 */
Al Viro38897172010-07-22 01:13:36 +04001430 if (!performed_allocation) {
1431 dquot_free_block_nodirty(inode, *count);
1432 mark_inode_dirty(inode);
1433 }
Martin J. Bligha686cd82007-10-16 23:30:46 -07001434 brelse(bitmap_bh);
1435 return 0;
1436}
1437
1438ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1439{
1440 unsigned long count = 1;
1441
1442 return ext2_new_blocks(inode, goal, &count, errp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443}
1444
Valerie Henson21730ee2006-06-25 05:48:12 -07001445#ifdef EXT2FS_DEBUG
1446
Akinobu Mitaecd0afa2012-07-30 14:41:05 -07001447unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
Valerie Henson21730ee2006-06-25 05:48:12 -07001448{
Akinobu Mitaecd0afa2012-07-30 14:41:05 -07001449 return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
Valerie Henson21730ee2006-06-25 05:48:12 -07001450}
1451
1452#endif /* EXT2FS_DEBUG */
1453
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454unsigned long ext2_count_free_blocks (struct super_block * sb)
1455{
1456 struct ext2_group_desc * desc;
1457 unsigned long desc_count = 0;
1458 int i;
1459#ifdef EXT2FS_DEBUG
1460 unsigned long bitmap_count, x;
1461 struct ext2_super_block *es;
1462
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 es = EXT2_SB(sb)->s_es;
1464 desc_count = 0;
1465 bitmap_count = 0;
1466 desc = NULL;
1467 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1468 struct buffer_head *bitmap_bh;
1469 desc = ext2_get_group_desc (sb, i, NULL);
1470 if (!desc)
1471 continue;
1472 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1473 bitmap_bh = read_block_bitmap(sb, i);
1474 if (!bitmap_bh)
1475 continue;
1476
1477 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1478 printk ("group %d: stored = %d, counted = %lu\n",
1479 i, le16_to_cpu(desc->bg_free_blocks_count), x);
1480 bitmap_count += x;
1481 brelse(bitmap_bh);
1482 }
1483 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1484 (long)le32_to_cpu(es->s_free_blocks_count),
1485 desc_count, bitmap_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 return bitmap_count;
1487#else
1488 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1489 desc = ext2_get_group_desc (sb, i, NULL);
1490 if (!desc)
1491 continue;
1492 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1493 }
1494 return desc_count;
1495#endif
1496}
1497
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498static inline int test_root(int a, int b)
1499{
1500 int num = b;
1501
1502 while (a > num)
1503 num *= b;
1504 return num == a;
1505}
1506
1507static int ext2_group_sparse(int group)
1508{
1509 if (group <= 1)
1510 return 1;
1511 return (test_root(group, 3) || test_root(group, 5) ||
1512 test_root(group, 7));
1513}
1514
1515/**
1516 * ext2_bg_has_super - number of blocks used by the superblock in group
1517 * @sb: superblock for filesystem
1518 * @group: group number to check
1519 *
1520 * Return the number of blocks used by the superblock (primary or backup)
1521 * in this group. Currently this will be only 0 or 1.
1522 */
1523int ext2_bg_has_super(struct super_block *sb, int group)
1524{
1525 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1526 !ext2_group_sparse(group))
1527 return 0;
1528 return 1;
1529}
1530
1531/**
1532 * ext2_bg_num_gdb - number of blocks used by the group table in group
1533 * @sb: superblock for filesystem
1534 * @group: group number to check
1535 *
1536 * Return the number of blocks used by the group descriptor table
1537 * (primary or backup) in this group. In the future there may be a
1538 * different number of descriptor blocks in each group.
1539 */
1540unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1541{
Akinobu Mita859cb932008-02-06 01:40:17 -08001542 return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543}
1544