blob: 9f9992b37924a43eb4da2c56ecb9b65f68d628a2 [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
Martin J. Bligha686cd82007-10-16 23:30:46 -0700162static void group_adjust_blocks(struct super_block *sb, int group_no,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 struct ext2_group_desc *desc, struct buffer_head *bh, int count)
164{
165 if (count) {
166 struct ext2_sb_info *sbi = EXT2_SB(sb);
167 unsigned free_blocks;
168
169 spin_lock(sb_bgl_lock(sbi, group_no));
170 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
171 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
172 spin_unlock(sb_bgl_lock(sbi, group_no));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 mark_buffer_dirty(bh);
174 }
175}
176
Martin J. Bligha686cd82007-10-16 23:30:46 -0700177/*
178 * The reservation window structure operations
179 * --------------------------------------------
180 * Operations include:
181 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
182 *
183 * We use a red-black tree to represent per-filesystem reservation
184 * windows.
185 *
186 */
187
188/**
189 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
190 * @rb_root: root of per-filesystem reservation rb tree
191 * @verbose: verbose mode
192 * @fn: function which wishes to dump the reservation map
193 *
194 * If verbose is turned on, it will print the whole block reservation
195 * windows(start, end). Otherwise, it will only print out the "bad" windows,
196 * those windows that overlap with their immediate neighbors.
197 */
198#if 1
199static void __rsv_window_dump(struct rb_root *root, int verbose,
200 const char *fn)
201{
202 struct rb_node *n;
203 struct ext2_reserve_window_node *rsv, *prev;
204 int bad;
205
206restart:
207 n = rb_first(root);
208 bad = 0;
209 prev = NULL;
210
211 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
212 while (n) {
213 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
214 if (verbose)
215 printk("reservation window 0x%p "
216 "start: %lu, end: %lu\n",
217 rsv, rsv->rsv_start, rsv->rsv_end);
218 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
219 printk("Bad reservation %p (start >= end)\n",
220 rsv);
221 bad = 1;
222 }
223 if (prev && prev->rsv_end >= rsv->rsv_start) {
224 printk("Bad reservation %p (prev->end >= start)\n",
225 rsv);
226 bad = 1;
227 }
228 if (bad) {
229 if (!verbose) {
230 printk("Restarting reservation walk in verbose mode\n");
231 verbose = 1;
232 goto restart;
233 }
234 }
235 n = rb_next(n);
236 prev = rsv;
237 }
238 printk("Window map complete.\n");
Julia Lawall2c116192008-04-28 02:16:02 -0700239 BUG_ON(bad);
Martin J. Bligha686cd82007-10-16 23:30:46 -0700240}
241#define rsv_window_dump(root, verbose) \
Harvey Harrison605afd62008-04-28 02:16:03 -0700242 __rsv_window_dump((root), (verbose), __func__)
Martin J. Bligha686cd82007-10-16 23:30:46 -0700243#else
244#define rsv_window_dump(root, verbose) do {} while (0)
245#endif
246
247/**
248 * goal_in_my_reservation()
249 * @rsv: inode's reservation window
250 * @grp_goal: given goal block relative to the allocation block group
251 * @group: the current allocation block group
252 * @sb: filesystem super block
253 *
254 * Test if the given goal block (group relative) is within the file's
255 * own block reservation window range.
256 *
257 * If the reservation window is outside the goal allocation group, return 0;
258 * grp_goal (given goal block) could be -1, which means no specific
259 * goal block. In this case, always return 1.
260 * If the goal block is within the reservation window, return 1;
261 * otherwise, return 0;
262 */
263static int
264goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
265 unsigned int group, struct super_block * sb)
266{
267 ext2_fsblk_t group_first_block, group_last_block;
268
269 group_first_block = ext2_group_first_block_no(sb, group);
270 group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
271
272 if ((rsv->_rsv_start > group_last_block) ||
273 (rsv->_rsv_end < group_first_block))
274 return 0;
275 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
276 || (grp_goal + group_first_block > rsv->_rsv_end)))
277 return 0;
278 return 1;
279}
280
281/**
282 * search_reserve_window()
283 * @rb_root: root of reservation tree
284 * @goal: target allocation block
285 *
286 * Find the reserved window which includes the goal, or the previous one
287 * if the goal is not in any window.
288 * Returns NULL if there are no windows or if all windows start after the goal.
289 */
290static struct ext2_reserve_window_node *
291search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
292{
293 struct rb_node *n = root->rb_node;
294 struct ext2_reserve_window_node *rsv;
295
296 if (!n)
297 return NULL;
298
299 do {
300 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
301
302 if (goal < rsv->rsv_start)
303 n = n->rb_left;
304 else if (goal > rsv->rsv_end)
305 n = n->rb_right;
306 else
307 return rsv;
308 } while (n);
309 /*
310 * We've fallen off the end of the tree: the goal wasn't inside
311 * any particular node. OK, the previous node must be to one
312 * side of the interval containing the goal. If it's the RHS,
313 * we need to back up one.
314 */
315 if (rsv->rsv_start > goal) {
316 n = rb_prev(&rsv->rsv_node);
317 rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
318 }
319 return rsv;
320}
321
322/*
323 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
324 * @sb: super block
325 * @rsv: reservation window to add
326 *
327 * Must be called with rsv_lock held.
328 */
329void ext2_rsv_window_add(struct super_block *sb,
330 struct ext2_reserve_window_node *rsv)
331{
332 struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
333 struct rb_node *node = &rsv->rsv_node;
334 ext2_fsblk_t start = rsv->rsv_start;
335
336 struct rb_node ** p = &root->rb_node;
337 struct rb_node * parent = NULL;
338 struct ext2_reserve_window_node *this;
339
340 while (*p)
341 {
342 parent = *p;
343 this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
344
345 if (start < this->rsv_start)
346 p = &(*p)->rb_left;
347 else if (start > this->rsv_end)
348 p = &(*p)->rb_right;
349 else {
350 rsv_window_dump(root, 1);
351 BUG();
352 }
353 }
354
355 rb_link_node(node, parent, p);
356 rb_insert_color(node, root);
357}
358
359/**
360 * rsv_window_remove() -- unlink a window from the reservation rb tree
361 * @sb: super block
362 * @rsv: reservation window to remove
363 *
364 * Mark the block reservation window as not allocated, and unlink it
365 * from the filesystem reservation window rb tree. Must be called with
366 * rsv_lock held.
367 */
368static void rsv_window_remove(struct super_block *sb,
369 struct ext2_reserve_window_node *rsv)
370{
371 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
372 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
373 rsv->rsv_alloc_hit = 0;
374 rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
375}
376
377/*
378 * rsv_is_empty() -- Check if the reservation window is allocated.
379 * @rsv: given reservation window to check
380 *
381 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
382 */
383static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
384{
385 /* a valid reservation end block could not be 0 */
386 return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
387}
388
389/**
390 * ext2_init_block_alloc_info()
391 * @inode: file inode structure
392 *
393 * Allocate and initialize the reservation window structure, and
394 * link the window to the ext2 inode structure at last
395 *
396 * The reservation window structure is only dynamically allocated
397 * and linked to ext2 inode the first time the open file
398 * needs a new block. So, before every ext2_new_block(s) call, for
399 * regular files, we should check whether the reservation window
400 * structure exists or not. In the latter case, this function is called.
401 * Fail to do so will result in block reservation being turned off for that
402 * open file.
403 *
404 * This function is called from ext2_get_blocks_handle(), also called
405 * when setting the reservation window size through ioctl before the file
406 * is open for write (needs block allocation).
407 *
408 * Needs truncate_mutex protection prior to calling this function.
409 */
410void ext2_init_block_alloc_info(struct inode *inode)
411{
412 struct ext2_inode_info *ei = EXT2_I(inode);
Julia Lawall6e3d6ca2011-08-04 12:29:32 +0200413 struct ext2_block_alloc_info *block_i;
Martin J. Bligha686cd82007-10-16 23:30:46 -0700414 struct super_block *sb = inode->i_sb;
415
416 block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
417 if (block_i) {
418 struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
419
420 rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
421 rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
422
423 /*
424 * if filesystem is mounted with NORESERVATION, the goal
425 * reservation window size is set to zero to indicate
426 * block reservation is off
427 */
428 if (!test_opt(sb, RESERVATION))
429 rsv->rsv_goal_size = 0;
430 else
431 rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
432 rsv->rsv_alloc_hit = 0;
433 block_i->last_alloc_logical_block = 0;
434 block_i->last_alloc_physical_block = 0;
435 }
436 ei->i_block_alloc_info = block_i;
437}
438
439/**
440 * ext2_discard_reservation()
441 * @inode: inode
442 *
443 * Discard(free) block reservation window on last file close, or truncate
444 * or at last iput().
445 *
446 * It is being called in three cases:
447 * ext2_release_file(): last writer closes the file
448 * ext2_clear_inode(): last iput(), when nobody links to this file.
449 * ext2_truncate(): when the block indirect map is about to change.
450 */
451void ext2_discard_reservation(struct inode *inode)
452{
453 struct ext2_inode_info *ei = EXT2_I(inode);
454 struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
455 struct ext2_reserve_window_node *rsv;
456 spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
457
458 if (!block_i)
459 return;
460
461 rsv = &block_i->rsv_window_node;
462 if (!rsv_is_empty(&rsv->rsv_window)) {
463 spin_lock(rsv_lock);
464 if (!rsv_is_empty(&rsv->rsv_window))
465 rsv_window_remove(inode->i_sb, rsv);
466 spin_unlock(rsv_lock);
467 }
468}
469
470/**
Wang Sheng-Hui03248762012-05-18 15:04:45 +0800471 * ext2_free_blocks() -- Free given blocks and update quota and i_blocks
Martin J. Bligha686cd82007-10-16 23:30:46 -0700472 * @inode: inode
Anatol Pomozov4907cb72012-09-01 10:31:09 -0700473 * @block: start physical block to free
Martin J. Bligha686cd82007-10-16 23:30:46 -0700474 * @count: number of blocks to free
475 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476void ext2_free_blocks (struct inode * inode, unsigned long block,
477 unsigned long count)
478{
479 struct buffer_head *bitmap_bh = NULL;
480 struct buffer_head * bh2;
481 unsigned long block_group;
482 unsigned long bit;
483 unsigned long i;
484 unsigned long overflow;
485 struct super_block * sb = inode->i_sb;
486 struct ext2_sb_info * sbi = EXT2_SB(sb);
487 struct ext2_group_desc * desc;
488 struct ext2_super_block * es = sbi->s_es;
489 unsigned freed = 0, group_freed;
490
491 if (block < le32_to_cpu(es->s_first_data_block) ||
492 block + count < block ||
493 block + count > le32_to_cpu(es->s_blocks_count)) {
494 ext2_error (sb, "ext2_free_blocks",
495 "Freeing blocks not in datazone - "
496 "block = %lu, count = %lu", block, count);
497 goto error_return;
498 }
499
500 ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
501
502do_more:
503 overflow = 0;
504 block_group = (block - le32_to_cpu(es->s_first_data_block)) /
505 EXT2_BLOCKS_PER_GROUP(sb);
506 bit = (block - le32_to_cpu(es->s_first_data_block)) %
507 EXT2_BLOCKS_PER_GROUP(sb);
508 /*
509 * Check to see if we are freeing blocks across a group
510 * boundary.
511 */
512 if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
513 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
514 count -= overflow;
515 }
516 brelse(bitmap_bh);
517 bitmap_bh = read_block_bitmap(sb, block_group);
518 if (!bitmap_bh)
519 goto error_return;
520
521 desc = ext2_get_group_desc (sb, block_group, &bh2);
522 if (!desc)
523 goto error_return;
524
525 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
526 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
527 in_range (block, le32_to_cpu(desc->bg_inode_table),
528 sbi->s_itb_per_group) ||
529 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -0800530 sbi->s_itb_per_group)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 ext2_error (sb, "ext2_free_blocks",
532 "Freeing blocks in system zones - "
533 "Block = %lu, count = %lu",
534 block, count);
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -0800535 goto error_return;
536 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537
538 for (i = 0, group_freed = 0; i < count; i++) {
539 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
540 bit + i, bitmap_bh->b_data)) {
Harvey Harrison605afd62008-04-28 02:16:03 -0700541 ext2_error(sb, __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 "bit already cleared for block %lu", block + i);
543 } else {
544 group_freed++;
545 }
546 }
547
548 mark_buffer_dirty(bitmap_bh);
549 if (sb->s_flags & MS_SYNCHRONOUS)
550 sync_dirty_buffer(bitmap_bh);
551
Martin J. Bligha686cd82007-10-16 23:30:46 -0700552 group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 freed += group_freed;
554
555 if (overflow) {
556 block += count;
557 count = overflow;
558 goto do_more;
559 }
560error_return:
561 brelse(bitmap_bh);
Wang Shilong8e3dffc2013-02-07 22:57:53 +0800562 if (freed) {
Wang Shilong712ddc52013-02-07 22:57:54 +0800563 percpu_counter_add(&sbi->s_freeblocks_counter, freed);
Wang Shilong8e3dffc2013-02-07 22:57:53 +0800564 dquot_free_block_nodirty(inode, freed);
565 mark_inode_dirty(inode);
566 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567}
568
Martin J. Bligha686cd82007-10-16 23:30:46 -0700569/**
570 * bitmap_search_next_usable_block()
571 * @start: the starting block (group relative) of the search
572 * @bh: bufferhead contains the block group bitmap
573 * @maxblocks: the ending block (group relative) of the reservation
574 *
575 * The bitmap search --- search forward through the actual bitmap on disk until
576 * we find a bit free.
577 */
578static ext2_grpblk_t
579bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
580 ext2_grpblk_t maxblocks)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581{
Martin J. Bligha686cd82007-10-16 23:30:46 -0700582 ext2_grpblk_t next;
583
584 next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
585 if (next >= maxblocks)
586 return -1;
587 return next;
588}
589
590/**
591 * find_next_usable_block()
592 * @start: the starting block (group relative) to find next
593 * allocatable block in bitmap.
594 * @bh: bufferhead contains the block group bitmap
595 * @maxblocks: the ending block (group relative) for the search
596 *
597 * Find an allocatable block in a bitmap. We perform the "most
598 * appropriate allocation" algorithm of looking for a free block near
599 * the initial goal; then for a free byte somewhere in the bitmap;
600 * then for any free bit in the bitmap.
601 */
602static ext2_grpblk_t
603find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
604{
605 ext2_grpblk_t here, next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 char *p, *r;
607
Martin J. Bligha686cd82007-10-16 23:30:46 -0700608 if (start > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 /*
610 * The goal was occupied; search forward for a free
611 * block within the next XX blocks.
612 *
613 * end_goal is more or less random, but it has to be
614 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
615 * next 64-bit boundary is simple..
616 */
Martin J. Bligha686cd82007-10-16 23:30:46 -0700617 ext2_grpblk_t end_goal = (start + 63) & ~63;
618 if (end_goal > maxblocks)
619 end_goal = maxblocks;
620 here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
621 if (here < end_goal)
622 return here;
623 ext2_debug("Bit not found near goal\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 }
625
Martin J. Bligha686cd82007-10-16 23:30:46 -0700626 here = start;
627 if (here < 0)
628 here = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629
Martin J. Bligha686cd82007-10-16 23:30:46 -0700630 p = ((char *)bh->b_data) + (here >> 3);
631 r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
632 next = (r - ((char *)bh->b_data)) << 3;
633
634 if (next < maxblocks && next >= here)
635 return next;
636
637 here = bitmap_search_next_usable_block(here, bh, maxblocks);
638 return here;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639}
640
Namhyung Kim26f78b72010-09-26 15:31:00 +0900641/**
Martin J. Bligha686cd82007-10-16 23:30:46 -0700642 * ext2_try_to_allocate()
643 * @sb: superblock
Martin J. Bligha686cd82007-10-16 23:30:46 -0700644 * @group: given allocation block group
645 * @bitmap_bh: bufferhead holds the block bitmap
646 * @grp_goal: given target block within the group
647 * @count: target number of blocks to allocate
648 * @my_rsv: reservation window
649 *
650 * Attempt to allocate blocks within a give range. Set the range of allocation
651 * first, then find the first free bit(s) from the bitmap (within the range),
652 * and at last, allocate the blocks by claiming the found free bit as allocated.
653 *
654 * To set the range of this allocation:
655 * if there is a reservation window, only try to allocate block(s)
656 * from the file's own reservation window;
657 * Otherwise, the allocation range starts from the give goal block,
658 * ends at the block group's last block.
659 *
660 * If we failed to allocate the desired block then we may end up crossing to a
661 * new bitmap.
662 */
663static int
664ext2_try_to_allocate(struct super_block *sb, int group,
665 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
666 unsigned long *count,
667 struct ext2_reserve_window *my_rsv)
668{
669 ext2_fsblk_t group_first_block;
670 ext2_grpblk_t start, end;
671 unsigned long num = 0;
672
673 /* we do allocation within the reservation window if we have a window */
674 if (my_rsv) {
675 group_first_block = ext2_group_first_block_no(sb, group);
676 if (my_rsv->_rsv_start >= group_first_block)
677 start = my_rsv->_rsv_start - group_first_block;
678 else
679 /* reservation window cross group boundary */
680 start = 0;
681 end = my_rsv->_rsv_end - group_first_block + 1;
682 if (end > EXT2_BLOCKS_PER_GROUP(sb))
683 /* reservation window crosses group boundary */
684 end = EXT2_BLOCKS_PER_GROUP(sb);
685 if ((start <= grp_goal) && (grp_goal < end))
686 start = grp_goal;
687 else
688 grp_goal = -1;
689 } else {
690 if (grp_goal > 0)
691 start = grp_goal;
692 else
693 start = 0;
694 end = EXT2_BLOCKS_PER_GROUP(sb);
695 }
696
697 BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
698
699repeat:
700 if (grp_goal < 0) {
701 grp_goal = find_next_usable_block(start, bitmap_bh, end);
702 if (grp_goal < 0)
703 goto fail_access;
704 if (!my_rsv) {
705 int i;
706
707 for (i = 0; i < 7 && grp_goal > start &&
708 !ext2_test_bit(grp_goal - 1,
709 bitmap_bh->b_data);
710 i++, grp_goal--)
711 ;
712 }
713 }
714 start = grp_goal;
715
716 if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
717 bitmap_bh->b_data)) {
718 /*
719 * The block was allocated by another thread, or it was
720 * allocated and then freed by another thread
721 */
722 start++;
723 grp_goal++;
724 if (start >= end)
725 goto fail_access;
726 goto repeat;
727 }
728 num++;
729 grp_goal++;
730 while (num < *count && grp_goal < end
731 && !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
732 grp_goal, bitmap_bh->b_data)) {
733 num++;
734 grp_goal++;
735 }
736 *count = num;
737 return grp_goal - num;
738fail_access:
739 *count = num;
740 return -1;
741}
742
743/**
744 * find_next_reservable_window():
745 * find a reservable space within the given range.
746 * It does not allocate the reservation window for now:
747 * alloc_new_reservation() will do the work later.
748 *
749 * @search_head: the head of the searching list;
750 * This is not necessarily the list head of the whole filesystem
751 *
752 * We have both head and start_block to assist the search
753 * for the reservable space. The list starts from head,
754 * but we will shift to the place where start_block is,
755 * then start from there, when looking for a reservable space.
756 *
757 * @size: the target new reservation window size
758 *
759 * @group_first_block: the first block we consider to start
760 * the real search from
761 *
762 * @last_block:
763 * the maximum block number that our goal reservable space
764 * could start from. This is normally the last block in this
765 * group. The search will end when we found the start of next
766 * possible reservable space is out of this boundary.
767 * This could handle the cross boundary reservation window
768 * request.
769 *
770 * basically we search from the given range, rather than the whole
771 * reservation double linked list, (start_block, last_block)
772 * to find a free region that is of my size and has not
773 * been reserved.
774 *
775 */
776static int find_next_reservable_window(
777 struct ext2_reserve_window_node *search_head,
778 struct ext2_reserve_window_node *my_rsv,
779 struct super_block * sb,
780 ext2_fsblk_t start_block,
781 ext2_fsblk_t last_block)
782{
783 struct rb_node *next;
784 struct ext2_reserve_window_node *rsv, *prev;
785 ext2_fsblk_t cur;
786 int size = my_rsv->rsv_goal_size;
787
788 /* TODO: make the start of the reservation window byte-aligned */
789 /* cur = *start_block & ~7;*/
790 cur = start_block;
791 rsv = search_head;
792 if (!rsv)
793 return -1;
794
795 while (1) {
796 if (cur <= rsv->rsv_end)
797 cur = rsv->rsv_end + 1;
798
799 /* TODO?
800 * in the case we could not find a reservable space
801 * that is what is expected, during the re-search, we could
802 * remember what's the largest reservable space we could have
803 * and return that one.
804 *
805 * For now it will fail if we could not find the reservable
806 * space with expected-size (or more)...
807 */
808 if (cur > last_block)
809 return -1; /* fail */
810
811 prev = rsv;
812 next = rb_next(&rsv->rsv_node);
813 rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
814
815 /*
816 * Reached the last reservation, we can just append to the
817 * previous one.
818 */
819 if (!next)
820 break;
821
822 if (cur + size <= rsv->rsv_start) {
823 /*
824 * Found a reserveable space big enough. We could
825 * have a reservation across the group boundary here
826 */
827 break;
828 }
829 }
830 /*
831 * we come here either :
832 * when we reach the end of the whole list,
833 * and there is empty reservable space after last entry in the list.
834 * append it to the end of the list.
835 *
836 * or we found one reservable space in the middle of the list,
837 * return the reservation window that we could append to.
838 * succeed.
839 */
840
841 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
842 rsv_window_remove(sb, my_rsv);
843
844 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300845 * Let's book the whole available window for now. We will check the
Martin J. Bligha686cd82007-10-16 23:30:46 -0700846 * disk bitmap later and then, if there are free blocks then we adjust
847 * the window size if it's larger than requested.
848 * Otherwise, we will remove this node from the tree next time
849 * call find_next_reservable_window.
850 */
851 my_rsv->rsv_start = cur;
852 my_rsv->rsv_end = cur + size - 1;
853 my_rsv->rsv_alloc_hit = 0;
854
855 if (prev != my_rsv)
856 ext2_rsv_window_add(sb, my_rsv);
857
858 return 0;
859}
860
861/**
862 * alloc_new_reservation()--allocate a new reservation window
863 *
864 * To make a new reservation, we search part of the filesystem
865 * reservation list (the list that inside the group). We try to
866 * allocate a new reservation window near the allocation goal,
867 * or the beginning of the group, if there is no goal.
868 *
869 * We first find a reservable space after the goal, then from
870 * there, we check the bitmap for the first free block after
871 * it. If there is no free block until the end of group, then the
872 * whole group is full, we failed. Otherwise, check if the free
873 * block is inside the expected reservable space, if so, we
874 * succeed.
875 * If the first free block is outside the reservable space, then
876 * start from the first free block, we search for next available
877 * space, and go on.
878 *
879 * on succeed, a new reservation will be found and inserted into the list
880 * It contains at least one free block, and it does not overlap with other
881 * reservation windows.
882 *
883 * failed: we failed to find a reservation window in this group
884 *
885 * @rsv: the reservation
886 *
887 * @grp_goal: The goal (group-relative). It is where the search for a
888 * free reservable space should start from.
889 * if we have a goal(goal >0 ), then start from there,
890 * no goal(goal = -1), we start from the first block
891 * of the group.
892 *
893 * @sb: the super block
894 * @group: the group we are trying to allocate in
895 * @bitmap_bh: the block group block bitmap
896 *
897 */
898static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
899 ext2_grpblk_t grp_goal, struct super_block *sb,
900 unsigned int group, struct buffer_head *bitmap_bh)
901{
902 struct ext2_reserve_window_node *search_head;
903 ext2_fsblk_t group_first_block, group_end_block, start_block;
904 ext2_grpblk_t first_free_block;
905 struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
906 unsigned long size;
907 int ret;
908 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
909
910 group_first_block = ext2_group_first_block_no(sb, group);
911 group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
912
913 if (grp_goal < 0)
914 start_block = group_first_block;
915 else
916 start_block = grp_goal + group_first_block;
917
918 size = my_rsv->rsv_goal_size;
919
920 if (!rsv_is_empty(&my_rsv->rsv_window)) {
921 /*
922 * if the old reservation is cross group boundary
923 * and if the goal is inside the old reservation window,
924 * we will come here when we just failed to allocate from
925 * the first part of the window. We still have another part
926 * that belongs to the next group. In this case, there is no
927 * point to discard our window and try to allocate a new one
928 * in this group(which will fail). we should
929 * keep the reservation window, just simply move on.
930 *
931 * Maybe we could shift the start block of the reservation
932 * window to the first block of next group.
933 */
934
935 if ((my_rsv->rsv_start <= group_end_block) &&
936 (my_rsv->rsv_end > group_end_block) &&
937 (start_block >= my_rsv->rsv_start))
938 return -1;
939
940 if ((my_rsv->rsv_alloc_hit >
941 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
942 /*
943 * if the previously allocation hit ratio is
944 * greater than 1/2, then we double the size of
945 * the reservation window the next time,
946 * otherwise we keep the same size window
947 */
948 size = size * 2;
949 if (size > EXT2_MAX_RESERVE_BLOCKS)
950 size = EXT2_MAX_RESERVE_BLOCKS;
951 my_rsv->rsv_goal_size= size;
952 }
953 }
954
955 spin_lock(rsv_lock);
956 /*
957 * shift the search start to the window near the goal block
958 */
959 search_head = search_reserve_window(fs_rsv_root, start_block);
960
961 /*
962 * find_next_reservable_window() simply finds a reservable window
963 * inside the given range(start_block, group_end_block).
964 *
965 * To make sure the reservation window has a free bit inside it, we
966 * need to check the bitmap after we found a reservable window.
967 */
968retry:
969 ret = find_next_reservable_window(search_head, my_rsv, sb,
970 start_block, group_end_block);
971
972 if (ret == -1) {
973 if (!rsv_is_empty(&my_rsv->rsv_window))
974 rsv_window_remove(sb, my_rsv);
975 spin_unlock(rsv_lock);
976 return -1;
977 }
978
979 /*
980 * On success, find_next_reservable_window() returns the
981 * reservation window where there is a reservable space after it.
982 * Before we reserve this reservable space, we need
983 * to make sure there is at least a free block inside this region.
984 *
985 * Search the first free bit on the block bitmap. Search starts from
986 * the start block of the reservable space we just found.
987 */
988 spin_unlock(rsv_lock);
989 first_free_block = bitmap_search_next_usable_block(
990 my_rsv->rsv_start - group_first_block,
991 bitmap_bh, group_end_block - group_first_block + 1);
992
993 if (first_free_block < 0) {
994 /*
995 * no free block left on the bitmap, no point
996 * to reserve the space. return failed.
997 */
998 spin_lock(rsv_lock);
999 if (!rsv_is_empty(&my_rsv->rsv_window))
1000 rsv_window_remove(sb, my_rsv);
1001 spin_unlock(rsv_lock);
1002 return -1; /* failed */
1003 }
1004
1005 start_block = first_free_block + group_first_block;
1006 /*
1007 * check if the first free block is within the
1008 * free space we just reserved
1009 */
1010 if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1011 return 0; /* success */
1012 /*
1013 * if the first free bit we found is out of the reservable space
1014 * continue search for next reservable space,
1015 * start from where the free block is,
1016 * we also shift the list head to where we stopped last time
1017 */
1018 search_head = my_rsv;
1019 spin_lock(rsv_lock);
1020 goto retry;
1021}
1022
1023/**
1024 * try_to_extend_reservation()
1025 * @my_rsv: given reservation window
1026 * @sb: super block
1027 * @size: the delta to extend
1028 *
1029 * Attempt to expand the reservation window large enough to have
1030 * required number of free blocks
1031 *
1032 * Since ext2_try_to_allocate() will always allocate blocks within
1033 * the reservation window range, if the window size is too small,
1034 * multiple blocks allocation has to stop at the end of the reservation
1035 * window. To make this more efficient, given the total number of
1036 * blocks needed and the current size of the window, we try to
1037 * expand the reservation window size if necessary on a best-effort
1038 * basis before ext2_new_blocks() tries to allocate blocks.
1039 */
1040static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1041 struct super_block *sb, int size)
1042{
1043 struct ext2_reserve_window_node *next_rsv;
1044 struct rb_node *next;
1045 spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1046
1047 if (!spin_trylock(rsv_lock))
1048 return;
1049
1050 next = rb_next(&my_rsv->rsv_node);
1051
1052 if (!next)
1053 my_rsv->rsv_end += size;
1054 else {
1055 next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1056
1057 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1058 my_rsv->rsv_end += size;
1059 else
1060 my_rsv->rsv_end = next_rsv->rsv_start - 1;
1061 }
1062 spin_unlock(rsv_lock);
1063}
1064
1065/**
1066 * ext2_try_to_allocate_with_rsv()
1067 * @sb: superblock
1068 * @group: given allocation block group
1069 * @bitmap_bh: bufferhead holds the block bitmap
1070 * @grp_goal: given target block within the group
1071 * @count: target number of blocks to allocate
1072 * @my_rsv: reservation window
1073 *
1074 * This is the main function used to allocate a new block and its reservation
1075 * window.
1076 *
1077 * Each time when a new block allocation is need, first try to allocate from
1078 * its own reservation. If it does not have a reservation window, instead of
1079 * looking for a free bit on bitmap first, then look up the reservation list to
1080 * see if it is inside somebody else's reservation window, we try to allocate a
1081 * reservation window for it starting from the goal first. Then do the block
1082 * allocation within the reservation window.
1083 *
1084 * This will avoid keeping on searching the reservation list again and
1085 * again when somebody is looking for a free block (without
1086 * reservation), and there are lots of free blocks, but they are all
1087 * being reserved.
1088 *
1089 * We use a red-black tree for the per-filesystem reservation list.
1090 */
1091static ext2_grpblk_t
1092ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1093 struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1094 struct ext2_reserve_window_node * my_rsv,
1095 unsigned long *count)
1096{
1097 ext2_fsblk_t group_first_block, group_last_block;
1098 ext2_grpblk_t ret = 0;
1099 unsigned long num = *count;
1100
1101 /*
1102 * we don't deal with reservation when
1103 * filesystem is mounted without reservation
1104 * or the file is not a regular file
1105 * or last attempt to allocate a block with reservation turned on failed
1106 */
1107 if (my_rsv == NULL) {
1108 return ext2_try_to_allocate(sb, group, bitmap_bh,
1109 grp_goal, count, NULL);
1110 }
1111 /*
1112 * grp_goal is a group relative block number (if there is a goal)
1113 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1114 * first block is a filesystem wide block number
1115 * first block is the block number of the first block in this group
1116 */
1117 group_first_block = ext2_group_first_block_no(sb, group);
1118 group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
1119
1120 /*
1121 * Basically we will allocate a new block from inode's reservation
1122 * window.
1123 *
1124 * We need to allocate a new reservation window, if:
1125 * a) inode does not have a reservation window; or
1126 * b) last attempt to allocate a block from existing reservation
1127 * failed; or
1128 * c) we come here with a goal and with a reservation window
1129 *
1130 * We do not need to allocate a new reservation window if we come here
1131 * at the beginning with a goal and the goal is inside the window, or
1132 * we don't have a goal but already have a reservation window.
1133 * then we could go to allocate from the reservation window directly.
1134 */
1135 while (1) {
1136 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1137 !goal_in_my_reservation(&my_rsv->rsv_window,
1138 grp_goal, group, sb)) {
1139 if (my_rsv->rsv_goal_size < *count)
1140 my_rsv->rsv_goal_size = *count;
1141 ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1142 group, bitmap_bh);
1143 if (ret < 0)
1144 break; /* failed */
1145
1146 if (!goal_in_my_reservation(&my_rsv->rsv_window,
1147 grp_goal, group, sb))
1148 grp_goal = -1;
1149 } else if (grp_goal >= 0) {
1150 int curr = my_rsv->rsv_end -
1151 (grp_goal + group_first_block) + 1;
1152
1153 if (curr < *count)
1154 try_to_extend_reservation(my_rsv, sb,
1155 *count - curr);
1156 }
1157
1158 if ((my_rsv->rsv_start > group_last_block) ||
1159 (my_rsv->rsv_end < group_first_block)) {
1160 rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1161 BUG();
1162 }
1163 ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1164 &num, &my_rsv->rsv_window);
1165 if (ret >= 0) {
1166 my_rsv->rsv_alloc_hit += num;
1167 *count = num;
1168 break; /* succeed */
1169 }
1170 num = *count;
1171 }
1172 return ret;
1173}
1174
1175/**
1176 * ext2_has_free_blocks()
1177 * @sbi: in-core super block structure.
1178 *
1179 * Check if filesystem has at least 1 free block available for allocation.
1180 */
1181static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1182{
1183 ext2_fsblk_t free_blocks, root_blocks;
1184
1185 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1186 root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1187 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
Eric W. Biedermanb8a9f9e2012-02-07 15:39:12 -08001188 !uid_eq(sbi->s_resuid, current_fsuid()) &&
1189 (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1190 !in_group_p (sbi->s_resgid))) {
Martin J. Bligha686cd82007-10-16 23:30:46 -07001191 return 0;
1192 }
1193 return 1;
1194}
1195
1196/*
1197 * ext2_new_blocks() -- core block(s) allocation function
1198 * @inode: file inode
1199 * @goal: given target block(filesystem wide)
1200 * @count: target number of blocks to allocate
1201 * @errp: error code
1202 *
1203 * ext2_new_blocks uses a goal block to assist allocation. If the goal is
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204 * free, or there is a free block within 32 blocks of the goal, that block
1205 * is allocated. Otherwise a forward search is made for a free block; within
1206 * each block group the search first looks for an entire free byte in the block
1207 * bitmap, and then for any free bit if that fails.
1208 * This function also updates quota and i_blocks field.
1209 */
Martin J. Bligha686cd82007-10-16 23:30:46 -07001210ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1211 unsigned long *count, int *errp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212{
1213 struct buffer_head *bitmap_bh = NULL;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001214 struct buffer_head *gdp_bh;
1215 int group_no;
1216 int goal_group;
1217 ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1218 ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1219 ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1220 int bgi; /* blockgroup iteration index */
1221 int performed_allocation = 0;
1222 ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1223 struct super_block *sb;
1224 struct ext2_group_desc *gdp;
1225 struct ext2_super_block *es;
1226 struct ext2_sb_info *sbi;
1227 struct ext2_reserve_window_node *my_rsv = NULL;
1228 struct ext2_block_alloc_info *block_i;
1229 unsigned short windowsz = 0;
1230 unsigned long ngroups;
1231 unsigned long num = *count;
Christoph Hellwig5dd40562010-03-03 09:05:00 -05001232 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233
Martin J. Bligha686cd82007-10-16 23:30:46 -07001234 *errp = -ENOSPC;
1235 sb = inode->i_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236
Martin J. Bligha686cd82007-10-16 23:30:46 -07001237 /*
1238 * Check quota for allocation of this block.
1239 */
Christoph Hellwig5dd40562010-03-03 09:05:00 -05001240 ret = dquot_alloc_block(inode, num);
1241 if (ret) {
1242 *errp = ret;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001243 return 0;
1244 }
1245
1246 sbi = EXT2_SB(sb);
1247 es = EXT2_SB(sb)->s_es;
1248 ext2_debug("goal=%lu.\n", goal);
1249 /*
1250 * Allocate a block from reservation only when
1251 * filesystem is mounted with reservation(default,-o reservation), and
1252 * it's a regular file, and
1253 * the desired window size is greater than 0 (One could use ioctl
1254 * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1255 * reservation on that particular file)
1256 */
1257 block_i = EXT2_I(inode)->i_block_alloc_info;
1258 if (block_i) {
1259 windowsz = block_i->rsv_window_node.rsv_goal_size;
1260 if (windowsz > 0)
1261 my_rsv = &block_i->rsv_window_node;
1262 }
1263
1264 if (!ext2_has_free_blocks(sbi)) {
1265 *errp = -ENOSPC;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 goto out;
1267 }
1268
Martin J. Bligha686cd82007-10-16 23:30:46 -07001269 /*
1270 * First, test whether the goal block is free.
1271 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272 if (goal < le32_to_cpu(es->s_first_data_block) ||
1273 goal >= le32_to_cpu(es->s_blocks_count))
1274 goal = le32_to_cpu(es->s_first_data_block);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001275 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1276 EXT2_BLOCKS_PER_GROUP(sb);
1277 goal_group = group_no;
1278retry_alloc:
1279 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1280 if (!gdp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281 goto io_error;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001282
1283 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1284 /*
1285 * if there is not enough free blocks to make a new resevation
1286 * turn off reservation for this allocation
1287 */
1288 if (my_rsv && (free_blocks < windowsz)
Mingming Caod707d312008-10-15 22:04:01 -07001289 && (free_blocks > 0)
Martin J. Bligha686cd82007-10-16 23:30:46 -07001290 && (rsv_is_empty(&my_rsv->rsv_window)))
1291 my_rsv = NULL;
1292
1293 if (free_blocks > 0) {
1294 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1295 EXT2_BLOCKS_PER_GROUP(sb));
1296 bitmap_bh = read_block_bitmap(sb, group_no);
1297 if (!bitmap_bh)
1298 goto io_error;
1299 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1300 bitmap_bh, grp_target_blk,
1301 my_rsv, &num);
1302 if (grp_alloc_blk >= 0)
1303 goto allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 }
1305
Martin J. Bligha686cd82007-10-16 23:30:46 -07001306 ngroups = EXT2_SB(sb)->s_groups_count;
1307 smp_rmb();
1308
1309 /*
Akinobu Mita144704e2008-02-06 01:40:15 -08001310 * Now search the rest of the groups. We assume that
1311 * group_no and gdp correctly point to the last group visited.
Martin J. Bligha686cd82007-10-16 23:30:46 -07001312 */
1313 for (bgi = 0; bgi < ngroups; bgi++) {
1314 group_no++;
1315 if (group_no >= ngroups)
1316 group_no = 0;
1317 gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1318 if (!gdp)
1319 goto io_error;
1320
1321 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1322 /*
Jan Kara46891532010-03-29 13:55:39 +02001323 * skip this group (and avoid loading bitmap) if there
1324 * are no free blocks
1325 */
1326 if (!free_blocks)
1327 continue;
1328 /*
Martin J. Bligha686cd82007-10-16 23:30:46 -07001329 * skip this group if the number of
1330 * free blocks is less than half of the reservation
1331 * window size.
1332 */
Mingming Caod707d312008-10-15 22:04:01 -07001333 if (my_rsv && (free_blocks <= (windowsz/2)))
Martin J. Bligha686cd82007-10-16 23:30:46 -07001334 continue;
1335
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 brelse(bitmap_bh);
1337 bitmap_bh = read_block_bitmap(sb, group_no);
1338 if (!bitmap_bh)
1339 goto io_error;
Martin J. Bligha686cd82007-10-16 23:30:46 -07001340 /*
1341 * try to allocate block(s) from this group, without a goal(-1).
1342 */
1343 grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1344 bitmap_bh, -1, my_rsv, &num);
1345 if (grp_alloc_blk >= 0)
1346 goto allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001349 * We may end up a bogus earlier ENOSPC error due to
Martin J. Bligha686cd82007-10-16 23:30:46 -07001350 * filesystem is "full" of reservations, but
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001351 * there maybe indeed free blocks available on disk
Martin J. Bligha686cd82007-10-16 23:30:46 -07001352 * In this case, we just forget about the reservations
1353 * just do block allocation as without reservations.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 */
Martin J. Bligha686cd82007-10-16 23:30:46 -07001355 if (my_rsv) {
1356 my_rsv = NULL;
1357 windowsz = 0;
1358 group_no = goal_group;
1359 goto retry_alloc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 }
Martin J. Bligha686cd82007-10-16 23:30:46 -07001361 /* No space left on the device */
1362 *errp = -ENOSPC;
1363 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364
Martin J. Bligha686cd82007-10-16 23:30:46 -07001365allocated:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 ext2_debug("using block group %d(%d)\n",
Martin J. Bligha686cd82007-10-16 23:30:46 -07001368 group_no, gdp->bg_free_blocks_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369
Martin J. Bligha686cd82007-10-16 23:30:46 -07001370 ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371
Martin J. Bligha686cd82007-10-16 23:30:46 -07001372 if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1373 in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1374 in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1375 EXT2_SB(sb)->s_itb_per_group) ||
1376 in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -08001377 EXT2_SB(sb)->s_itb_per_group)) {
Martin J. Bligha686cd82007-10-16 23:30:46 -07001378 ext2_error(sb, "ext2_new_blocks",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 "Allocating block in system zone - "
Martin J. Bligha686cd82007-10-16 23:30:46 -07001380 "blocks from "E2FSBLK", length %lu",
1381 ret_block, num);
Aneesh Kumar K.V8b915822008-04-28 02:16:04 -07001382 /*
1383 * ext2_try_to_allocate marked the blocks we allocated as in
1384 * use. So we may want to selectively mark some of the blocks
1385 * as free
1386 */
1387 goto retry_alloc;
Aneesh Kumar K.V7f0adae2008-02-06 01:36:17 -08001388 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389
Martin J. Bligha686cd82007-10-16 23:30:46 -07001390 performed_allocation = 1;
1391
1392 if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1393 ext2_error(sb, "ext2_new_blocks",
1394 "block("E2FSBLK") >= blocks count(%d) - "
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 "block_group = %d, es == %p ", ret_block,
1396 le32_to_cpu(es->s_blocks_count), group_no, es);
Martin J. Bligha686cd82007-10-16 23:30:46 -07001397 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
Martin J. Bligha686cd82007-10-16 23:30:46 -07001400 group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1401 percpu_counter_sub(&sbi->s_freeblocks_counter, num);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402
1403 mark_buffer_dirty(bitmap_bh);
1404 if (sb->s_flags & MS_SYNCHRONOUS)
1405 sync_dirty_buffer(bitmap_bh);
1406
Martin J. Bligha686cd82007-10-16 23:30:46 -07001407 *errp = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 brelse(bitmap_bh);
Wang Shilong8e3dffc2013-02-07 22:57:53 +08001409 if (num < *count) {
1410 dquot_free_block_nodirty(inode, *count-num);
1411 mark_inode_dirty(inode);
1412 *count = num;
1413 }
Martin J. Bligha686cd82007-10-16 23:30:46 -07001414 return ret_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415
1416io_error:
Martin J. Bligha686cd82007-10-16 23:30:46 -07001417 *errp = -EIO;
1418out:
1419 /*
1420 * Undo the block allocation
1421 */
Al Viro38897172010-07-22 01:13:36 +04001422 if (!performed_allocation) {
1423 dquot_free_block_nodirty(inode, *count);
1424 mark_inode_dirty(inode);
1425 }
Martin J. Bligha686cd82007-10-16 23:30:46 -07001426 brelse(bitmap_bh);
1427 return 0;
1428}
1429
1430ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1431{
1432 unsigned long count = 1;
1433
1434 return ext2_new_blocks(inode, goal, &count, errp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435}
1436
Valerie Henson21730ee2006-06-25 05:48:12 -07001437#ifdef EXT2FS_DEBUG
1438
Akinobu Mitaecd0afa2012-07-30 14:41:05 -07001439unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
Valerie Henson21730ee2006-06-25 05:48:12 -07001440{
Akinobu Mitaecd0afa2012-07-30 14:41:05 -07001441 return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
Valerie Henson21730ee2006-06-25 05:48:12 -07001442}
1443
1444#endif /* EXT2FS_DEBUG */
1445
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446unsigned long ext2_count_free_blocks (struct super_block * sb)
1447{
1448 struct ext2_group_desc * desc;
1449 unsigned long desc_count = 0;
1450 int i;
1451#ifdef EXT2FS_DEBUG
1452 unsigned long bitmap_count, x;
1453 struct ext2_super_block *es;
1454
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 es = EXT2_SB(sb)->s_es;
1456 desc_count = 0;
1457 bitmap_count = 0;
1458 desc = NULL;
1459 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1460 struct buffer_head *bitmap_bh;
1461 desc = ext2_get_group_desc (sb, i, NULL);
1462 if (!desc)
1463 continue;
1464 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1465 bitmap_bh = read_block_bitmap(sb, i);
1466 if (!bitmap_bh)
1467 continue;
1468
1469 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1470 printk ("group %d: stored = %d, counted = %lu\n",
1471 i, le16_to_cpu(desc->bg_free_blocks_count), x);
1472 bitmap_count += x;
1473 brelse(bitmap_bh);
1474 }
1475 printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1476 (long)le32_to_cpu(es->s_free_blocks_count),
1477 desc_count, bitmap_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 return bitmap_count;
1479#else
1480 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1481 desc = ext2_get_group_desc (sb, i, NULL);
1482 if (!desc)
1483 continue;
1484 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1485 }
1486 return desc_count;
1487#endif
1488}
1489
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490static inline int test_root(int a, int b)
1491{
1492 int num = b;
1493
1494 while (a > num)
1495 num *= b;
1496 return num == a;
1497}
1498
1499static int ext2_group_sparse(int group)
1500{
1501 if (group <= 1)
1502 return 1;
1503 return (test_root(group, 3) || test_root(group, 5) ||
1504 test_root(group, 7));
1505}
1506
1507/**
1508 * ext2_bg_has_super - number of blocks used by the superblock in group
1509 * @sb: superblock for filesystem
1510 * @group: group number to check
1511 *
1512 * Return the number of blocks used by the superblock (primary or backup)
1513 * in this group. Currently this will be only 0 or 1.
1514 */
1515int ext2_bg_has_super(struct super_block *sb, int group)
1516{
1517 if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1518 !ext2_group_sparse(group))
1519 return 0;
1520 return 1;
1521}
1522
1523/**
1524 * ext2_bg_num_gdb - number of blocks used by the group table in group
1525 * @sb: superblock for filesystem
1526 * @group: group number to check
1527 *
1528 * Return the number of blocks used by the group descriptor table
1529 * (primary or backup) in this group. In the future there may be a
1530 * different number of descriptor blocks in each group.
1531 */
1532unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1533{
Akinobu Mita859cb932008-02-06 01:40:17 -08001534 return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535}
1536