udf: Move filling of partition descriptor info into a separate function
[linux-2.6] / fs / ext4 / balloc.c
1 /*
2  *  linux/fs/ext4/balloc.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10  *  Big-endian to little-endian byte-swapping/bitmaps by
11  *        David S. Miller (davem@caip.rutgers.edu), 1995
12  */
13
14 #include <linux/time.h>
15 #include <linux/capability.h>
16 #include <linux/fs.h>
17 #include <linux/jbd2.h>
18 #include <linux/ext4_fs.h>
19 #include <linux/ext4_jbd2.h>
20 #include <linux/quotaops.h>
21 #include <linux/buffer_head.h>
22
23 #include "group.h"
24 /*
25  * balloc.c contains the blocks allocation and deallocation routines
26  */
27
28 /*
29  * Calculate the block group number and offset, given a block number
30  */
31 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
32                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
33 {
34         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
35         ext4_grpblk_t offset;
36
37         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
38         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
39         if (offsetp)
40                 *offsetp = offset;
41         if (blockgrpp)
42                 *blockgrpp = blocknr;
43
44 }
45
46 /* Initializes an uninitialized block bitmap if given, and returns the
47  * number of blocks free in the group. */
48 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
49                  ext4_group_t block_group, struct ext4_group_desc *gdp)
50 {
51         unsigned long start;
52         int bit, bit_max;
53         unsigned free_blocks, group_blocks;
54         struct ext4_sb_info *sbi = EXT4_SB(sb);
55
56         if (bh) {
57                 J_ASSERT_BH(bh, buffer_locked(bh));
58
59                 /* If checksum is bad mark all blocks used to prevent allocation
60                  * essentially implementing a per-group read-only flag. */
61                 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
62                         ext4_error(sb, __FUNCTION__,
63                                   "Checksum bad for group %lu\n", block_group);
64                         gdp->bg_free_blocks_count = 0;
65                         gdp->bg_free_inodes_count = 0;
66                         gdp->bg_itable_unused = 0;
67                         memset(bh->b_data, 0xff, sb->s_blocksize);
68                         return 0;
69                 }
70                 memset(bh->b_data, 0, sb->s_blocksize);
71         }
72
73         /* Check for superblock and gdt backups in this group */
74         bit_max = ext4_bg_has_super(sb, block_group);
75
76         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
77             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
78                           sbi->s_desc_per_block) {
79                 if (bit_max) {
80                         bit_max += ext4_bg_num_gdb(sb, block_group);
81                         bit_max +=
82                                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
83                 }
84         } else { /* For META_BG_BLOCK_GROUPS */
85                 int group_rel = (block_group -
86                                  le32_to_cpu(sbi->s_es->s_first_meta_bg)) %
87                                 EXT4_DESC_PER_BLOCK(sb);
88                 if (group_rel == 0 || group_rel == 1 ||
89                     (group_rel == EXT4_DESC_PER_BLOCK(sb) - 1))
90                         bit_max += 1;
91         }
92
93         if (block_group == sbi->s_groups_count - 1) {
94                 /*
95                  * Even though mke2fs always initialize first and last group
96                  * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
97                  * to make sure we calculate the right free blocks
98                  */
99                 group_blocks = ext4_blocks_count(sbi->s_es) -
100                         le32_to_cpu(sbi->s_es->s_first_data_block) -
101                         (EXT4_BLOCKS_PER_GROUP(sb) * (sbi->s_groups_count -1));
102         } else {
103                 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
104         }
105
106         free_blocks = group_blocks - bit_max;
107
108         if (bh) {
109                 for (bit = 0; bit < bit_max; bit++)
110                         ext4_set_bit(bit, bh->b_data);
111
112                 start = block_group * EXT4_BLOCKS_PER_GROUP(sb) +
113                         le32_to_cpu(sbi->s_es->s_first_data_block);
114
115                 /* Set bits for block and inode bitmaps, and inode table */
116                 ext4_set_bit(ext4_block_bitmap(sb, gdp) - start, bh->b_data);
117                 ext4_set_bit(ext4_inode_bitmap(sb, gdp) - start, bh->b_data);
118                 for (bit = (ext4_inode_table(sb, gdp) - start),
119                      bit_max = bit + sbi->s_itb_per_group; bit < bit_max; bit++)
120                         ext4_set_bit(bit, bh->b_data);
121
122                 /*
123                  * Also if the number of blocks within the group is
124                  * less than the blocksize * 8 ( which is the size
125                  * of bitmap ), set rest of the block bitmap to 1
126                  */
127                 mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
128         }
129
130         return free_blocks - sbi->s_itb_per_group - 2;
131 }
132
133
134 /*
135  * The free blocks are managed by bitmaps.  A file system contains several
136  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
137  * block for inodes, N blocks for the inode table and data blocks.
138  *
139  * The file system contains group descriptors which are located after the
140  * super block.  Each descriptor contains the number of the bitmap block and
141  * the free blocks count in the block.  The descriptors are loaded in memory
142  * when a file system is mounted (see ext4_fill_super).
143  */
144
145
146 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
147
148 /**
149  * ext4_get_group_desc() -- load group descriptor from disk
150  * @sb:                 super block
151  * @block_group:        given block group
152  * @bh:                 pointer to the buffer head to store the block
153  *                      group descriptor
154  */
155 struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
156                                              ext4_group_t block_group,
157                                              struct buffer_head ** bh)
158 {
159         unsigned long group_desc;
160         unsigned long offset;
161         struct ext4_group_desc * desc;
162         struct ext4_sb_info *sbi = EXT4_SB(sb);
163
164         if (block_group >= sbi->s_groups_count) {
165                 ext4_error (sb, "ext4_get_group_desc",
166                             "block_group >= groups_count - "
167                             "block_group = %lu, groups_count = %lu",
168                             block_group, sbi->s_groups_count);
169
170                 return NULL;
171         }
172         smp_rmb();
173
174         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
175         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
176         if (!sbi->s_group_desc[group_desc]) {
177                 ext4_error (sb, "ext4_get_group_desc",
178                             "Group descriptor not loaded - "
179                             "block_group = %lu, group_desc = %lu, desc = %lu",
180                              block_group, group_desc, offset);
181                 return NULL;
182         }
183
184         desc = (struct ext4_group_desc *)(
185                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
186                 offset * EXT4_DESC_SIZE(sb));
187         if (bh)
188                 *bh = sbi->s_group_desc[group_desc];
189         return desc;
190 }
191
192 static int ext4_valid_block_bitmap(struct super_block *sb,
193                                         struct ext4_group_desc *desc,
194                                         unsigned int block_group,
195                                         struct buffer_head *bh)
196 {
197         ext4_grpblk_t offset;
198         ext4_grpblk_t next_zero_bit;
199         ext4_fsblk_t bitmap_blk;
200         ext4_fsblk_t group_first_block;
201
202         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
203                 /* with FLEX_BG, the inode/block bitmaps and itable
204                  * blocks may not be in the group at all
205                  * so the bitmap validation will be skipped for those groups
206                  * or it has to also read the block group where the bitmaps
207                  * are located to verify they are set.
208                  */
209                 return 1;
210         }
211         group_first_block = ext4_group_first_block_no(sb, block_group);
212
213         /* check whether block bitmap block number is set */
214         bitmap_blk = ext4_block_bitmap(sb, desc);
215         offset = bitmap_blk - group_first_block;
216         if (!ext4_test_bit(offset, bh->b_data))
217                 /* bad block bitmap */
218                 goto err_out;
219
220         /* check whether the inode bitmap block number is set */
221         bitmap_blk = ext4_inode_bitmap(sb, desc);
222         offset = bitmap_blk - group_first_block;
223         if (!ext4_test_bit(offset, bh->b_data))
224                 /* bad block bitmap */
225                 goto err_out;
226
227         /* check whether the inode table block number is set */
228         bitmap_blk = ext4_inode_table(sb, desc);
229         offset = bitmap_blk - group_first_block;
230         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
231                                 offset + EXT4_SB(sb)->s_itb_per_group,
232                                 offset);
233         if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
234                 /* good bitmap for inode tables */
235                 return 1;
236
237 err_out:
238         ext4_error(sb, __FUNCTION__,
239                         "Invalid block bitmap - "
240                         "block_group = %d, block = %llu",
241                         block_group, bitmap_blk);
242         return 0;
243 }
244 /**
245  * read_block_bitmap()
246  * @sb:                 super block
247  * @block_group:        given block group
248  *
249  * Read the bitmap for a given block_group,and validate the
250  * bits for block/inode/inode tables are set in the bitmaps
251  *
252  * Return buffer_head on success or NULL in case of failure.
253  */
254 struct buffer_head *
255 read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
256 {
257         struct ext4_group_desc * desc;
258         struct buffer_head * bh = NULL;
259         ext4_fsblk_t bitmap_blk;
260
261         desc = ext4_get_group_desc(sb, block_group, NULL);
262         if (!desc)
263                 return NULL;
264         bitmap_blk = ext4_block_bitmap(sb, desc);
265         bh = sb_getblk(sb, bitmap_blk);
266         if (unlikely(!bh)) {
267                 ext4_error(sb, __FUNCTION__,
268                             "Cannot read block bitmap - "
269                             "block_group = %d, block_bitmap = %llu",
270                             (int)block_group, (unsigned long long)bitmap_blk);
271                 return NULL;
272         }
273         if (bh_uptodate_or_lock(bh))
274                 return bh;
275
276         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
277                 ext4_init_block_bitmap(sb, bh, block_group, desc);
278                 set_buffer_uptodate(bh);
279                 unlock_buffer(bh);
280                 return bh;
281         }
282         if (bh_submit_read(bh) < 0) {
283                 put_bh(bh);
284                 ext4_error(sb, __FUNCTION__,
285                             "Cannot read block bitmap - "
286                             "block_group = %d, block_bitmap = %llu",
287                             (int)block_group, (unsigned long long)bitmap_blk);
288                 return NULL;
289         }
290         if (!ext4_valid_block_bitmap(sb, desc, block_group, bh)) {
291                 put_bh(bh);
292                 return NULL;
293         }
294
295         return bh;
296 }
297 /*
298  * The reservation window structure operations
299  * --------------------------------------------
300  * Operations include:
301  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
302  *
303  * We use a red-black tree to represent per-filesystem reservation
304  * windows.
305  *
306  */
307
308 /**
309  * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
310  * @rb_root:            root of per-filesystem reservation rb tree
311  * @verbose:            verbose mode
312  * @fn:                 function which wishes to dump the reservation map
313  *
314  * If verbose is turned on, it will print the whole block reservation
315  * windows(start, end). Otherwise, it will only print out the "bad" windows,
316  * those windows that overlap with their immediate neighbors.
317  */
318 #if 1
319 static void __rsv_window_dump(struct rb_root *root, int verbose,
320                               const char *fn)
321 {
322         struct rb_node *n;
323         struct ext4_reserve_window_node *rsv, *prev;
324         int bad;
325
326 restart:
327         n = rb_first(root);
328         bad = 0;
329         prev = NULL;
330
331         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
332         while (n) {
333                 rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
334                 if (verbose)
335                         printk("reservation window 0x%p "
336                                "start:  %llu, end:  %llu\n",
337                                rsv, rsv->rsv_start, rsv->rsv_end);
338                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
339                         printk("Bad reservation %p (start >= end)\n",
340                                rsv);
341                         bad = 1;
342                 }
343                 if (prev && prev->rsv_end >= rsv->rsv_start) {
344                         printk("Bad reservation %p (prev->end >= start)\n",
345                                rsv);
346                         bad = 1;
347                 }
348                 if (bad) {
349                         if (!verbose) {
350                                 printk("Restarting reservation walk in verbose mode\n");
351                                 verbose = 1;
352                                 goto restart;
353                         }
354                 }
355                 n = rb_next(n);
356                 prev = rsv;
357         }
358         printk("Window map complete.\n");
359         if (bad)
360                 BUG();
361 }
362 #define rsv_window_dump(root, verbose) \
363         __rsv_window_dump((root), (verbose), __FUNCTION__)
364 #else
365 #define rsv_window_dump(root, verbose) do {} while (0)
366 #endif
367
368 /**
369  * goal_in_my_reservation()
370  * @rsv:                inode's reservation window
371  * @grp_goal:           given goal block relative to the allocation block group
372  * @group:              the current allocation block group
373  * @sb:                 filesystem super block
374  *
375  * Test if the given goal block (group relative) is within the file's
376  * own block reservation window range.
377  *
378  * If the reservation window is outside the goal allocation group, return 0;
379  * grp_goal (given goal block) could be -1, which means no specific
380  * goal block. In this case, always return 1.
381  * If the goal block is within the reservation window, return 1;
382  * otherwise, return 0;
383  */
384 static int
385 goal_in_my_reservation(struct ext4_reserve_window *rsv, ext4_grpblk_t grp_goal,
386                         ext4_group_t group, struct super_block *sb)
387 {
388         ext4_fsblk_t group_first_block, group_last_block;
389
390         group_first_block = ext4_group_first_block_no(sb, group);
391         group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
392
393         if ((rsv->_rsv_start > group_last_block) ||
394             (rsv->_rsv_end < group_first_block))
395                 return 0;
396         if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
397                 || (grp_goal + group_first_block > rsv->_rsv_end)))
398                 return 0;
399         return 1;
400 }
401
402 /**
403  * search_reserve_window()
404  * @rb_root:            root of reservation tree
405  * @goal:               target allocation block
406  *
407  * Find the reserved window which includes the goal, or the previous one
408  * if the goal is not in any window.
409  * Returns NULL if there are no windows or if all windows start after the goal.
410  */
411 static struct ext4_reserve_window_node *
412 search_reserve_window(struct rb_root *root, ext4_fsblk_t goal)
413 {
414         struct rb_node *n = root->rb_node;
415         struct ext4_reserve_window_node *rsv;
416
417         if (!n)
418                 return NULL;
419
420         do {
421                 rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
422
423                 if (goal < rsv->rsv_start)
424                         n = n->rb_left;
425                 else if (goal > rsv->rsv_end)
426                         n = n->rb_right;
427                 else
428                         return rsv;
429         } while (n);
430         /*
431          * We've fallen off the end of the tree: the goal wasn't inside
432          * any particular node.  OK, the previous node must be to one
433          * side of the interval containing the goal.  If it's the RHS,
434          * we need to back up one.
435          */
436         if (rsv->rsv_start > goal) {
437                 n = rb_prev(&rsv->rsv_node);
438                 rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
439         }
440         return rsv;
441 }
442
443 /**
444  * ext4_rsv_window_add() -- Insert a window to the block reservation rb tree.
445  * @sb:                 super block
446  * @rsv:                reservation window to add
447  *
448  * Must be called with rsv_lock hold.
449  */
450 void ext4_rsv_window_add(struct super_block *sb,
451                     struct ext4_reserve_window_node *rsv)
452 {
453         struct rb_root *root = &EXT4_SB(sb)->s_rsv_window_root;
454         struct rb_node *node = &rsv->rsv_node;
455         ext4_fsblk_t start = rsv->rsv_start;
456
457         struct rb_node ** p = &root->rb_node;
458         struct rb_node * parent = NULL;
459         struct ext4_reserve_window_node *this;
460
461         while (*p)
462         {
463                 parent = *p;
464                 this = rb_entry(parent, struct ext4_reserve_window_node, rsv_node);
465
466                 if (start < this->rsv_start)
467                         p = &(*p)->rb_left;
468                 else if (start > this->rsv_end)
469                         p = &(*p)->rb_right;
470                 else {
471                         rsv_window_dump(root, 1);
472                         BUG();
473                 }
474         }
475
476         rb_link_node(node, parent, p);
477         rb_insert_color(node, root);
478 }
479
480 /**
481  * ext4_rsv_window_remove() -- unlink a window from the reservation rb tree
482  * @sb:                 super block
483  * @rsv:                reservation window to remove
484  *
485  * Mark the block reservation window as not allocated, and unlink it
486  * from the filesystem reservation window rb tree. Must be called with
487  * rsv_lock hold.
488  */
489 static void rsv_window_remove(struct super_block *sb,
490                               struct ext4_reserve_window_node *rsv)
491 {
492         rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
493         rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
494         rsv->rsv_alloc_hit = 0;
495         rb_erase(&rsv->rsv_node, &EXT4_SB(sb)->s_rsv_window_root);
496 }
497
498 /*
499  * rsv_is_empty() -- Check if the reservation window is allocated.
500  * @rsv:                given reservation window to check
501  *
502  * returns 1 if the end block is EXT4_RESERVE_WINDOW_NOT_ALLOCATED.
503  */
504 static inline int rsv_is_empty(struct ext4_reserve_window *rsv)
505 {
506         /* a valid reservation end block could not be 0 */
507         return rsv->_rsv_end == EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
508 }
509
510 /**
511  * ext4_init_block_alloc_info()
512  * @inode:              file inode structure
513  *
514  * Allocate and initialize the  reservation window structure, and
515  * link the window to the ext4 inode structure at last
516  *
517  * The reservation window structure is only dynamically allocated
518  * and linked to ext4 inode the first time the open file
519  * needs a new block. So, before every ext4_new_block(s) call, for
520  * regular files, we should check whether the reservation window
521  * structure exists or not. In the latter case, this function is called.
522  * Fail to do so will result in block reservation being turned off for that
523  * open file.
524  *
525  * This function is called from ext4_get_blocks_handle(), also called
526  * when setting the reservation window size through ioctl before the file
527  * is open for write (needs block allocation).
528  *
529  * Needs down_write(i_data_sem) protection prior to call this function.
530  */
531 void ext4_init_block_alloc_info(struct inode *inode)
532 {
533         struct ext4_inode_info *ei = EXT4_I(inode);
534         struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
535         struct super_block *sb = inode->i_sb;
536
537         block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
538         if (block_i) {
539                 struct ext4_reserve_window_node *rsv = &block_i->rsv_window_node;
540
541                 rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
542                 rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
543
544                 /*
545                  * if filesystem is mounted with NORESERVATION, the goal
546                  * reservation window size is set to zero to indicate
547                  * block reservation is off
548                  */
549                 if (!test_opt(sb, RESERVATION))
550                         rsv->rsv_goal_size = 0;
551                 else
552                         rsv->rsv_goal_size = EXT4_DEFAULT_RESERVE_BLOCKS;
553                 rsv->rsv_alloc_hit = 0;
554                 block_i->last_alloc_logical_block = 0;
555                 block_i->last_alloc_physical_block = 0;
556         }
557         ei->i_block_alloc_info = block_i;
558 }
559
560 /**
561  * ext4_discard_reservation()
562  * @inode:              inode
563  *
564  * Discard(free) block reservation window on last file close, or truncate
565  * or at last iput().
566  *
567  * It is being called in three cases:
568  *      ext4_release_file(): last writer close the file
569  *      ext4_clear_inode(): last iput(), when nobody link to this file.
570  *      ext4_truncate(): when the block indirect map is about to change.
571  *
572  */
573 void ext4_discard_reservation(struct inode *inode)
574 {
575         struct ext4_inode_info *ei = EXT4_I(inode);
576         struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
577         struct ext4_reserve_window_node *rsv;
578         spinlock_t *rsv_lock = &EXT4_SB(inode->i_sb)->s_rsv_window_lock;
579
580         ext4_mb_discard_inode_preallocations(inode);
581
582         if (!block_i)
583                 return;
584
585         rsv = &block_i->rsv_window_node;
586         if (!rsv_is_empty(&rsv->rsv_window)) {
587                 spin_lock(rsv_lock);
588                 if (!rsv_is_empty(&rsv->rsv_window))
589                         rsv_window_remove(inode->i_sb, rsv);
590                 spin_unlock(rsv_lock);
591         }
592 }
593
594 /**
595  * ext4_free_blocks_sb() -- Free given blocks and update quota
596  * @handle:                     handle to this transaction
597  * @sb:                         super block
598  * @block:                      start physcial block to free
599  * @count:                      number of blocks to free
600  * @pdquot_freed_blocks:        pointer to quota
601  */
602 void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
603                          ext4_fsblk_t block, unsigned long count,
604                          unsigned long *pdquot_freed_blocks)
605 {
606         struct buffer_head *bitmap_bh = NULL;
607         struct buffer_head *gd_bh;
608         ext4_group_t block_group;
609         ext4_grpblk_t bit;
610         unsigned long i;
611         unsigned long overflow;
612         struct ext4_group_desc * desc;
613         struct ext4_super_block * es;
614         struct ext4_sb_info *sbi;
615         int err = 0, ret;
616         ext4_grpblk_t group_freed;
617
618         *pdquot_freed_blocks = 0;
619         sbi = EXT4_SB(sb);
620         es = sbi->s_es;
621         if (block < le32_to_cpu(es->s_first_data_block) ||
622             block + count < block ||
623             block + count > ext4_blocks_count(es)) {
624                 ext4_error (sb, "ext4_free_blocks",
625                             "Freeing blocks not in datazone - "
626                             "block = %llu, count = %lu", block, count);
627                 goto error_return;
628         }
629
630         ext4_debug ("freeing block(s) %llu-%llu\n", block, block + count - 1);
631
632 do_more:
633         overflow = 0;
634         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
635         /*
636          * Check to see if we are freeing blocks across a group
637          * boundary.
638          */
639         if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
640                 overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
641                 count -= overflow;
642         }
643         brelse(bitmap_bh);
644         bitmap_bh = read_block_bitmap(sb, block_group);
645         if (!bitmap_bh)
646                 goto error_return;
647         desc = ext4_get_group_desc (sb, block_group, &gd_bh);
648         if (!desc)
649                 goto error_return;
650
651         if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
652             in_range(ext4_inode_bitmap(sb, desc), block, count) ||
653             in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
654             in_range(block + count - 1, ext4_inode_table(sb, desc),
655                      sbi->s_itb_per_group)) {
656                 ext4_error (sb, "ext4_free_blocks",
657                             "Freeing blocks in system zones - "
658                             "Block = %llu, count = %lu",
659                             block, count);
660                 goto error_return;
661         }
662
663         /*
664          * We are about to start releasing blocks in the bitmap,
665          * so we need undo access.
666          */
667         /* @@@ check errors */
668         BUFFER_TRACE(bitmap_bh, "getting undo access");
669         err = ext4_journal_get_undo_access(handle, bitmap_bh);
670         if (err)
671                 goto error_return;
672
673         /*
674          * We are about to modify some metadata.  Call the journal APIs
675          * to unshare ->b_data if a currently-committing transaction is
676          * using it
677          */
678         BUFFER_TRACE(gd_bh, "get_write_access");
679         err = ext4_journal_get_write_access(handle, gd_bh);
680         if (err)
681                 goto error_return;
682
683         jbd_lock_bh_state(bitmap_bh);
684
685         for (i = 0, group_freed = 0; i < count; i++) {
686                 /*
687                  * An HJ special.  This is expensive...
688                  */
689 #ifdef CONFIG_JBD2_DEBUG
690                 jbd_unlock_bh_state(bitmap_bh);
691                 {
692                         struct buffer_head *debug_bh;
693                         debug_bh = sb_find_get_block(sb, block + i);
694                         if (debug_bh) {
695                                 BUFFER_TRACE(debug_bh, "Deleted!");
696                                 if (!bh2jh(bitmap_bh)->b_committed_data)
697                                         BUFFER_TRACE(debug_bh,
698                                                 "No commited data in bitmap");
699                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
700                                 __brelse(debug_bh);
701                         }
702                 }
703                 jbd_lock_bh_state(bitmap_bh);
704 #endif
705                 if (need_resched()) {
706                         jbd_unlock_bh_state(bitmap_bh);
707                         cond_resched();
708                         jbd_lock_bh_state(bitmap_bh);
709                 }
710                 /* @@@ This prevents newly-allocated data from being
711                  * freed and then reallocated within the same
712                  * transaction.
713                  *
714                  * Ideally we would want to allow that to happen, but to
715                  * do so requires making jbd2_journal_forget() capable of
716                  * revoking the queued write of a data block, which
717                  * implies blocking on the journal lock.  *forget()
718                  * cannot block due to truncate races.
719                  *
720                  * Eventually we can fix this by making jbd2_journal_forget()
721                  * return a status indicating whether or not it was able
722                  * to revoke the buffer.  On successful revoke, it is
723                  * safe not to set the allocation bit in the committed
724                  * bitmap, because we know that there is no outstanding
725                  * activity on the buffer any more and so it is safe to
726                  * reallocate it.
727                  */
728                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
729                 J_ASSERT_BH(bitmap_bh,
730                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
731                 ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
732                                 bh2jh(bitmap_bh)->b_committed_data);
733
734                 /*
735                  * We clear the bit in the bitmap after setting the committed
736                  * data bit, because this is the reverse order to that which
737                  * the allocator uses.
738                  */
739                 BUFFER_TRACE(bitmap_bh, "clear bit");
740                 if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
741                                                 bit + i, bitmap_bh->b_data)) {
742                         jbd_unlock_bh_state(bitmap_bh);
743                         ext4_error(sb, __FUNCTION__,
744                                    "bit already cleared for block %llu",
745                                    (ext4_fsblk_t)(block + i));
746                         jbd_lock_bh_state(bitmap_bh);
747                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
748                 } else {
749                         group_freed++;
750                 }
751         }
752         jbd_unlock_bh_state(bitmap_bh);
753
754         spin_lock(sb_bgl_lock(sbi, block_group));
755         desc->bg_free_blocks_count =
756                 cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
757                         group_freed);
758         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
759         spin_unlock(sb_bgl_lock(sbi, block_group));
760         percpu_counter_add(&sbi->s_freeblocks_counter, count);
761
762         /* We dirtied the bitmap block */
763         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
764         err = ext4_journal_dirty_metadata(handle, bitmap_bh);
765
766         /* And the group descriptor block */
767         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
768         ret = ext4_journal_dirty_metadata(handle, gd_bh);
769         if (!err) err = ret;
770         *pdquot_freed_blocks += group_freed;
771
772         if (overflow && !err) {
773                 block += count;
774                 count = overflow;
775                 goto do_more;
776         }
777         sb->s_dirt = 1;
778 error_return:
779         brelse(bitmap_bh);
780         ext4_std_error(sb, err);
781         return;
782 }
783
784 /**
785  * ext4_free_blocks() -- Free given blocks and update quota
786  * @handle:             handle for this transaction
787  * @inode:              inode
788  * @block:              start physical block to free
789  * @count:              number of blocks to count
790  * @metadata:           Are these metadata blocks
791  */
792 void ext4_free_blocks(handle_t *handle, struct inode *inode,
793                         ext4_fsblk_t block, unsigned long count,
794                         int metadata)
795 {
796         struct super_block * sb;
797         unsigned long dquot_freed_blocks;
798
799         /* this isn't the right place to decide whether block is metadata
800          * inode.c/extents.c knows better, but for safety ... */
801         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
802                         ext4_should_journal_data(inode))
803                 metadata = 1;
804
805         sb = inode->i_sb;
806
807         if (!test_opt(sb, MBALLOC) || !EXT4_SB(sb)->s_group_info)
808                 ext4_free_blocks_sb(handle, sb, block, count,
809                                                 &dquot_freed_blocks);
810         else
811                 ext4_mb_free_blocks(handle, inode, block, count,
812                                                 metadata, &dquot_freed_blocks);
813         if (dquot_freed_blocks)
814                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
815         return;
816 }
817
818 /**
819  * ext4_test_allocatable()
820  * @nr:                 given allocation block group
821  * @bh:                 bufferhead contains the bitmap of the given block group
822  *
823  * For ext4 allocations, we must not reuse any blocks which are
824  * allocated in the bitmap buffer's "last committed data" copy.  This
825  * prevents deletes from freeing up the page for reuse until we have
826  * committed the delete transaction.
827  *
828  * If we didn't do this, then deleting something and reallocating it as
829  * data would allow the old block to be overwritten before the
830  * transaction committed (because we force data to disk before commit).
831  * This would lead to corruption if we crashed between overwriting the
832  * data and committing the delete.
833  *
834  * @@@ We may want to make this allocation behaviour conditional on
835  * data-writes at some point, and disable it for metadata allocations or
836  * sync-data inodes.
837  */
838 static int ext4_test_allocatable(ext4_grpblk_t nr, struct buffer_head *bh)
839 {
840         int ret;
841         struct journal_head *jh = bh2jh(bh);
842
843         if (ext4_test_bit(nr, bh->b_data))
844                 return 0;
845
846         jbd_lock_bh_state(bh);
847         if (!jh->b_committed_data)
848                 ret = 1;
849         else
850                 ret = !ext4_test_bit(nr, jh->b_committed_data);
851         jbd_unlock_bh_state(bh);
852         return ret;
853 }
854
855 /**
856  * bitmap_search_next_usable_block()
857  * @start:              the starting block (group relative) of the search
858  * @bh:                 bufferhead contains the block group bitmap
859  * @maxblocks:          the ending block (group relative) of the reservation
860  *
861  * The bitmap search --- search forward alternately through the actual
862  * bitmap on disk and the last-committed copy in journal, until we find a
863  * bit free in both bitmaps.
864  */
865 static ext4_grpblk_t
866 bitmap_search_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
867                                         ext4_grpblk_t maxblocks)
868 {
869         ext4_grpblk_t next;
870         struct journal_head *jh = bh2jh(bh);
871
872         while (start < maxblocks) {
873                 next = ext4_find_next_zero_bit(bh->b_data, maxblocks, start);
874                 if (next >= maxblocks)
875                         return -1;
876                 if (ext4_test_allocatable(next, bh))
877                         return next;
878                 jbd_lock_bh_state(bh);
879                 if (jh->b_committed_data)
880                         start = ext4_find_next_zero_bit(jh->b_committed_data,
881                                                         maxblocks, next);
882                 jbd_unlock_bh_state(bh);
883         }
884         return -1;
885 }
886
887 /**
888  * find_next_usable_block()
889  * @start:              the starting block (group relative) to find next
890  *                      allocatable block in bitmap.
891  * @bh:                 bufferhead contains the block group bitmap
892  * @maxblocks:          the ending block (group relative) for the search
893  *
894  * Find an allocatable block in a bitmap.  We honor both the bitmap and
895  * its last-committed copy (if that exists), and perform the "most
896  * appropriate allocation" algorithm of looking for a free block near
897  * the initial goal; then for a free byte somewhere in the bitmap; then
898  * for any free bit in the bitmap.
899  */
900 static ext4_grpblk_t
901 find_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
902                         ext4_grpblk_t maxblocks)
903 {
904         ext4_grpblk_t here, next;
905         char *p, *r;
906
907         if (start > 0) {
908                 /*
909                  * The goal was occupied; search forward for a free
910                  * block within the next XX blocks.
911                  *
912                  * end_goal is more or less random, but it has to be
913                  * less than EXT4_BLOCKS_PER_GROUP. Aligning up to the
914                  * next 64-bit boundary is simple..
915                  */
916                 ext4_grpblk_t end_goal = (start + 63) & ~63;
917                 if (end_goal > maxblocks)
918                         end_goal = maxblocks;
919                 here = ext4_find_next_zero_bit(bh->b_data, end_goal, start);
920                 if (here < end_goal && ext4_test_allocatable(here, bh))
921                         return here;
922                 ext4_debug("Bit not found near goal\n");
923         }
924
925         here = start;
926         if (here < 0)
927                 here = 0;
928
929         p = ((char *)bh->b_data) + (here >> 3);
930         r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
931         next = (r - ((char *)bh->b_data)) << 3;
932
933         if (next < maxblocks && next >= start && ext4_test_allocatable(next, bh))
934                 return next;
935
936         /*
937          * The bitmap search --- search forward alternately through the actual
938          * bitmap and the last-committed copy until we find a bit free in
939          * both
940          */
941         here = bitmap_search_next_usable_block(here, bh, maxblocks);
942         return here;
943 }
944
945 /**
946  * claim_block()
947  * @block:              the free block (group relative) to allocate
948  * @bh:                 the bufferhead containts the block group bitmap
949  *
950  * We think we can allocate this block in this bitmap.  Try to set the bit.
951  * If that succeeds then check that nobody has allocated and then freed the
952  * block since we saw that is was not marked in b_committed_data.  If it _was_
953  * allocated and freed then clear the bit in the bitmap again and return
954  * zero (failure).
955  */
956 static inline int
957 claim_block(spinlock_t *lock, ext4_grpblk_t block, struct buffer_head *bh)
958 {
959         struct journal_head *jh = bh2jh(bh);
960         int ret;
961
962         if (ext4_set_bit_atomic(lock, block, bh->b_data))
963                 return 0;
964         jbd_lock_bh_state(bh);
965         if (jh->b_committed_data && ext4_test_bit(block,jh->b_committed_data)) {
966                 ext4_clear_bit_atomic(lock, block, bh->b_data);
967                 ret = 0;
968         } else {
969                 ret = 1;
970         }
971         jbd_unlock_bh_state(bh);
972         return ret;
973 }
974
975 /**
976  * ext4_try_to_allocate()
977  * @sb:                 superblock
978  * @handle:             handle to this transaction
979  * @group:              given allocation block group
980  * @bitmap_bh:          bufferhead holds the block bitmap
981  * @grp_goal:           given target block within the group
982  * @count:              target number of blocks to allocate
983  * @my_rsv:             reservation window
984  *
985  * Attempt to allocate blocks within a give range. Set the range of allocation
986  * first, then find the first free bit(s) from the bitmap (within the range),
987  * and at last, allocate the blocks by claiming the found free bit as allocated.
988  *
989  * To set the range of this allocation:
990  *      if there is a reservation window, only try to allocate block(s) from the
991  *      file's own reservation window;
992  *      Otherwise, the allocation range starts from the give goal block, ends at
993  *      the block group's last block.
994  *
995  * If we failed to allocate the desired block then we may end up crossing to a
996  * new bitmap.  In that case we must release write access to the old one via
997  * ext4_journal_release_buffer(), else we'll run out of credits.
998  */
999 static ext4_grpblk_t
1000 ext4_try_to_allocate(struct super_block *sb, handle_t *handle,
1001                         ext4_group_t group, struct buffer_head *bitmap_bh,
1002                         ext4_grpblk_t grp_goal, unsigned long *count,
1003                         struct ext4_reserve_window *my_rsv)
1004 {
1005         ext4_fsblk_t group_first_block;
1006         ext4_grpblk_t start, end;
1007         unsigned long num = 0;
1008
1009         /* we do allocation within the reservation window if we have a window */
1010         if (my_rsv) {
1011                 group_first_block = ext4_group_first_block_no(sb, group);
1012                 if (my_rsv->_rsv_start >= group_first_block)
1013                         start = my_rsv->_rsv_start - group_first_block;
1014                 else
1015                         /* reservation window cross group boundary */
1016                         start = 0;
1017                 end = my_rsv->_rsv_end - group_first_block + 1;
1018                 if (end > EXT4_BLOCKS_PER_GROUP(sb))
1019                         /* reservation window crosses group boundary */
1020                         end = EXT4_BLOCKS_PER_GROUP(sb);
1021                 if ((start <= grp_goal) && (grp_goal < end))
1022                         start = grp_goal;
1023                 else
1024                         grp_goal = -1;
1025         } else {
1026                 if (grp_goal > 0)
1027                         start = grp_goal;
1028                 else
1029                         start = 0;
1030                 end = EXT4_BLOCKS_PER_GROUP(sb);
1031         }
1032
1033         BUG_ON(start > EXT4_BLOCKS_PER_GROUP(sb));
1034
1035 repeat:
1036         if (grp_goal < 0 || !ext4_test_allocatable(grp_goal, bitmap_bh)) {
1037                 grp_goal = find_next_usable_block(start, bitmap_bh, end);
1038                 if (grp_goal < 0)
1039                         goto fail_access;
1040                 if (!my_rsv) {
1041                         int i;
1042
1043                         for (i = 0; i < 7 && grp_goal > start &&
1044                                         ext4_test_allocatable(grp_goal - 1,
1045                                                                 bitmap_bh);
1046                                         i++, grp_goal--)
1047                                 ;
1048                 }
1049         }
1050         start = grp_goal;
1051
1052         if (!claim_block(sb_bgl_lock(EXT4_SB(sb), group),
1053                 grp_goal, bitmap_bh)) {
1054                 /*
1055                  * The block was allocated by another thread, or it was
1056                  * allocated and then freed by another thread
1057                  */
1058                 start++;
1059                 grp_goal++;
1060                 if (start >= end)
1061                         goto fail_access;
1062                 goto repeat;
1063         }
1064         num++;
1065         grp_goal++;
1066         while (num < *count && grp_goal < end
1067                 && ext4_test_allocatable(grp_goal, bitmap_bh)
1068                 && claim_block(sb_bgl_lock(EXT4_SB(sb), group),
1069                                 grp_goal, bitmap_bh)) {
1070                 num++;
1071                 grp_goal++;
1072         }
1073         *count = num;
1074         return grp_goal - num;
1075 fail_access:
1076         *count = num;
1077         return -1;
1078 }
1079
1080 /**
1081  *      find_next_reservable_window():
1082  *              find a reservable space within the given range.
1083  *              It does not allocate the reservation window for now:
1084  *              alloc_new_reservation() will do the work later.
1085  *
1086  *      @search_head: the head of the searching list;
1087  *              This is not necessarily the list head of the whole filesystem
1088  *
1089  *              We have both head and start_block to assist the search
1090  *              for the reservable space. The list starts from head,
1091  *              but we will shift to the place where start_block is,
1092  *              then start from there, when looking for a reservable space.
1093  *
1094  *      @size: the target new reservation window size
1095  *
1096  *      @group_first_block: the first block we consider to start
1097  *                      the real search from
1098  *
1099  *      @last_block:
1100  *              the maximum block number that our goal reservable space
1101  *              could start from. This is normally the last block in this
1102  *              group. The search will end when we found the start of next
1103  *              possible reservable space is out of this boundary.
1104  *              This could handle the cross boundary reservation window
1105  *              request.
1106  *
1107  *      basically we search from the given range, rather than the whole
1108  *      reservation double linked list, (start_block, last_block)
1109  *      to find a free region that is of my size and has not
1110  *      been reserved.
1111  *
1112  */
1113 static int find_next_reservable_window(
1114                                 struct ext4_reserve_window_node *search_head,
1115                                 struct ext4_reserve_window_node *my_rsv,
1116                                 struct super_block * sb,
1117                                 ext4_fsblk_t start_block,
1118                                 ext4_fsblk_t last_block)
1119 {
1120         struct rb_node *next;
1121         struct ext4_reserve_window_node *rsv, *prev;
1122         ext4_fsblk_t cur;
1123         int size = my_rsv->rsv_goal_size;
1124
1125         /* TODO: make the start of the reservation window byte-aligned */
1126         /* cur = *start_block & ~7;*/
1127         cur = start_block;
1128         rsv = search_head;
1129         if (!rsv)
1130                 return -1;
1131
1132         while (1) {
1133                 if (cur <= rsv->rsv_end)
1134                         cur = rsv->rsv_end + 1;
1135
1136                 /* TODO?
1137                  * in the case we could not find a reservable space
1138                  * that is what is expected, during the re-search, we could
1139                  * remember what's the largest reservable space we could have
1140                  * and return that one.
1141                  *
1142                  * For now it will fail if we could not find the reservable
1143                  * space with expected-size (or more)...
1144                  */
1145                 if (cur > last_block)
1146                         return -1;              /* fail */
1147
1148                 prev = rsv;
1149                 next = rb_next(&rsv->rsv_node);
1150                 rsv = rb_entry(next,struct ext4_reserve_window_node,rsv_node);
1151
1152                 /*
1153                  * Reached the last reservation, we can just append to the
1154                  * previous one.
1155                  */
1156                 if (!next)
1157                         break;
1158
1159                 if (cur + size <= rsv->rsv_start) {
1160                         /*
1161                          * Found a reserveable space big enough.  We could
1162                          * have a reservation across the group boundary here
1163                          */
1164                         break;
1165                 }
1166         }
1167         /*
1168          * we come here either :
1169          * when we reach the end of the whole list,
1170          * and there is empty reservable space after last entry in the list.
1171          * append it to the end of the list.
1172          *
1173          * or we found one reservable space in the middle of the list,
1174          * return the reservation window that we could append to.
1175          * succeed.
1176          */
1177
1178         if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
1179                 rsv_window_remove(sb, my_rsv);
1180
1181         /*
1182          * Let's book the whole avaliable window for now.  We will check the
1183          * disk bitmap later and then, if there are free blocks then we adjust
1184          * the window size if it's larger than requested.
1185          * Otherwise, we will remove this node from the tree next time
1186          * call find_next_reservable_window.
1187          */
1188         my_rsv->rsv_start = cur;
1189         my_rsv->rsv_end = cur + size - 1;
1190         my_rsv->rsv_alloc_hit = 0;
1191
1192         if (prev != my_rsv)
1193                 ext4_rsv_window_add(sb, my_rsv);
1194
1195         return 0;
1196 }
1197
1198 /**
1199  *      alloc_new_reservation()--allocate a new reservation window
1200  *
1201  *              To make a new reservation, we search part of the filesystem
1202  *              reservation list (the list that inside the group). We try to
1203  *              allocate a new reservation window near the allocation goal,
1204  *              or the beginning of the group, if there is no goal.
1205  *
1206  *              We first find a reservable space after the goal, then from
1207  *              there, we check the bitmap for the first free block after
1208  *              it. If there is no free block until the end of group, then the
1209  *              whole group is full, we failed. Otherwise, check if the free
1210  *              block is inside the expected reservable space, if so, we
1211  *              succeed.
1212  *              If the first free block is outside the reservable space, then
1213  *              start from the first free block, we search for next available
1214  *              space, and go on.
1215  *
1216  *      on succeed, a new reservation will be found and inserted into the list
1217  *      It contains at least one free block, and it does not overlap with other
1218  *      reservation windows.
1219  *
1220  *      failed: we failed to find a reservation window in this group
1221  *
1222  *      @rsv: the reservation
1223  *
1224  *      @grp_goal: The goal (group-relative).  It is where the search for a
1225  *              free reservable space should start from.
1226  *              if we have a grp_goal(grp_goal >0 ), then start from there,
1227  *              no grp_goal(grp_goal = -1), we start from the first block
1228  *              of the group.
1229  *
1230  *      @sb: the super block
1231  *      @group: the group we are trying to allocate in
1232  *      @bitmap_bh: the block group block bitmap
1233  *
1234  */
1235 static int alloc_new_reservation(struct ext4_reserve_window_node *my_rsv,
1236                 ext4_grpblk_t grp_goal, struct super_block *sb,
1237                 ext4_group_t group, struct buffer_head *bitmap_bh)
1238 {
1239         struct ext4_reserve_window_node *search_head;
1240         ext4_fsblk_t group_first_block, group_end_block, start_block;
1241         ext4_grpblk_t first_free_block;
1242         struct rb_root *fs_rsv_root = &EXT4_SB(sb)->s_rsv_window_root;
1243         unsigned long size;
1244         int ret;
1245         spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
1246
1247         group_first_block = ext4_group_first_block_no(sb, group);
1248         group_end_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
1249
1250         if (grp_goal < 0)
1251                 start_block = group_first_block;
1252         else
1253                 start_block = grp_goal + group_first_block;
1254
1255         size = my_rsv->rsv_goal_size;
1256
1257         if (!rsv_is_empty(&my_rsv->rsv_window)) {
1258                 /*
1259                  * if the old reservation is cross group boundary
1260                  * and if the goal is inside the old reservation window,
1261                  * we will come here when we just failed to allocate from
1262                  * the first part of the window. We still have another part
1263                  * that belongs to the next group. In this case, there is no
1264                  * point to discard our window and try to allocate a new one
1265                  * in this group(which will fail). we should
1266                  * keep the reservation window, just simply move on.
1267                  *
1268                  * Maybe we could shift the start block of the reservation
1269                  * window to the first block of next group.
1270                  */
1271
1272                 if ((my_rsv->rsv_start <= group_end_block) &&
1273                                 (my_rsv->rsv_end > group_end_block) &&
1274                                 (start_block >= my_rsv->rsv_start))
1275                         return -1;
1276
1277                 if ((my_rsv->rsv_alloc_hit >
1278                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
1279                         /*
1280                          * if the previously allocation hit ratio is
1281                          * greater than 1/2, then we double the size of
1282                          * the reservation window the next time,
1283                          * otherwise we keep the same size window
1284                          */
1285                         size = size * 2;
1286                         if (size > EXT4_MAX_RESERVE_BLOCKS)
1287                                 size = EXT4_MAX_RESERVE_BLOCKS;
1288                         my_rsv->rsv_goal_size= size;
1289                 }
1290         }
1291
1292         spin_lock(rsv_lock);
1293         /*
1294          * shift the search start to the window near the goal block
1295          */
1296         search_head = search_reserve_window(fs_rsv_root, start_block);
1297
1298         /*
1299          * find_next_reservable_window() simply finds a reservable window
1300          * inside the given range(start_block, group_end_block).
1301          *
1302          * To make sure the reservation window has a free bit inside it, we
1303          * need to check the bitmap after we found a reservable window.
1304          */
1305 retry:
1306         ret = find_next_reservable_window(search_head, my_rsv, sb,
1307                                                 start_block, group_end_block);
1308
1309         if (ret == -1) {
1310                 if (!rsv_is_empty(&my_rsv->rsv_window))
1311                         rsv_window_remove(sb, my_rsv);
1312                 spin_unlock(rsv_lock);
1313                 return -1;
1314         }
1315
1316         /*
1317          * On success, find_next_reservable_window() returns the
1318          * reservation window where there is a reservable space after it.
1319          * Before we reserve this reservable space, we need
1320          * to make sure there is at least a free block inside this region.
1321          *
1322          * searching the first free bit on the block bitmap and copy of
1323          * last committed bitmap alternatively, until we found a allocatable
1324          * block. Search start from the start block of the reservable space
1325          * we just found.
1326          */
1327         spin_unlock(rsv_lock);
1328         first_free_block = bitmap_search_next_usable_block(
1329                         my_rsv->rsv_start - group_first_block,
1330                         bitmap_bh, group_end_block - group_first_block + 1);
1331
1332         if (first_free_block < 0) {
1333                 /*
1334                  * no free block left on the bitmap, no point
1335                  * to reserve the space. return failed.
1336                  */
1337                 spin_lock(rsv_lock);
1338                 if (!rsv_is_empty(&my_rsv->rsv_window))
1339                         rsv_window_remove(sb, my_rsv);
1340                 spin_unlock(rsv_lock);
1341                 return -1;              /* failed */
1342         }
1343
1344         start_block = first_free_block + group_first_block;
1345         /*
1346          * check if the first free block is within the
1347          * free space we just reserved
1348          */
1349         if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1350                 return 0;               /* success */
1351         /*
1352          * if the first free bit we found is out of the reservable space
1353          * continue search for next reservable space,
1354          * start from where the free block is,
1355          * we also shift the list head to where we stopped last time
1356          */
1357         search_head = my_rsv;
1358         spin_lock(rsv_lock);
1359         goto retry;
1360 }
1361
1362 /**
1363  * try_to_extend_reservation()
1364  * @my_rsv:             given reservation window
1365  * @sb:                 super block
1366  * @size:               the delta to extend
1367  *
1368  * Attempt to expand the reservation window large enough to have
1369  * required number of free blocks
1370  *
1371  * Since ext4_try_to_allocate() will always allocate blocks within
1372  * the reservation window range, if the window size is too small,
1373  * multiple blocks allocation has to stop at the end of the reservation
1374  * window. To make this more efficient, given the total number of
1375  * blocks needed and the current size of the window, we try to
1376  * expand the reservation window size if necessary on a best-effort
1377  * basis before ext4_new_blocks() tries to allocate blocks,
1378  */
1379 static void try_to_extend_reservation(struct ext4_reserve_window_node *my_rsv,
1380                         struct super_block *sb, int size)
1381 {
1382         struct ext4_reserve_window_node *next_rsv;
1383         struct rb_node *next;
1384         spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
1385
1386         if (!spin_trylock(rsv_lock))
1387                 return;
1388
1389         next = rb_next(&my_rsv->rsv_node);
1390
1391         if (!next)
1392                 my_rsv->rsv_end += size;
1393         else {
1394                 next_rsv = rb_entry(next, struct ext4_reserve_window_node, rsv_node);
1395
1396                 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1397                         my_rsv->rsv_end += size;
1398                 else
1399                         my_rsv->rsv_end = next_rsv->rsv_start - 1;
1400         }
1401         spin_unlock(rsv_lock);
1402 }
1403
1404 /**
1405  * ext4_try_to_allocate_with_rsv()
1406  * @sb:                 superblock
1407  * @handle:             handle to this transaction
1408  * @group:              given allocation block group
1409  * @bitmap_bh:          bufferhead holds the block bitmap
1410  * @grp_goal:           given target block within the group
1411  * @count:              target number of blocks to allocate
1412  * @my_rsv:             reservation window
1413  * @errp:               pointer to store the error code
1414  *
1415  * This is the main function used to allocate a new block and its reservation
1416  * window.
1417  *
1418  * Each time when a new block allocation is need, first try to allocate from
1419  * its own reservation.  If it does not have a reservation window, instead of
1420  * looking for a free bit on bitmap first, then look up the reservation list to
1421  * see if it is inside somebody else's reservation window, we try to allocate a
1422  * reservation window for it starting from the goal first. Then do the block
1423  * allocation within the reservation window.
1424  *
1425  * This will avoid keeping on searching the reservation list again and
1426  * again when somebody is looking for a free block (without
1427  * reservation), and there are lots of free blocks, but they are all
1428  * being reserved.
1429  *
1430  * We use a red-black tree for the per-filesystem reservation list.
1431  *
1432  */
1433 static ext4_grpblk_t
1434 ext4_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1435                         ext4_group_t group, struct buffer_head *bitmap_bh,
1436                         ext4_grpblk_t grp_goal,
1437                         struct ext4_reserve_window_node * my_rsv,
1438                         unsigned long *count, int *errp)
1439 {
1440         ext4_fsblk_t group_first_block, group_last_block;
1441         ext4_grpblk_t ret = 0;
1442         int fatal;
1443         unsigned long num = *count;
1444
1445         *errp = 0;
1446
1447         /*
1448          * Make sure we use undo access for the bitmap, because it is critical
1449          * that we do the frozen_data COW on bitmap buffers in all cases even
1450          * if the buffer is in BJ_Forget state in the committing transaction.
1451          */
1452         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1453         fatal = ext4_journal_get_undo_access(handle, bitmap_bh);
1454         if (fatal) {
1455                 *errp = fatal;
1456                 return -1;
1457         }
1458
1459         /*
1460          * we don't deal with reservation when
1461          * filesystem is mounted without reservation
1462          * or the file is not a regular file
1463          * or last attempt to allocate a block with reservation turned on failed
1464          */
1465         if (my_rsv == NULL ) {
1466                 ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
1467                                                 grp_goal, count, NULL);
1468                 goto out;
1469         }
1470         /*
1471          * grp_goal is a group relative block number (if there is a goal)
1472          * 0 <= grp_goal < EXT4_BLOCKS_PER_GROUP(sb)
1473          * first block is a filesystem wide block number
1474          * first block is the block number of the first block in this group
1475          */
1476         group_first_block = ext4_group_first_block_no(sb, group);
1477         group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
1478
1479         /*
1480          * Basically we will allocate a new block from inode's reservation
1481          * window.
1482          *
1483          * We need to allocate a new reservation window, if:
1484          * a) inode does not have a reservation window; or
1485          * b) last attempt to allocate a block from existing reservation
1486          *    failed; or
1487          * c) we come here with a goal and with a reservation window
1488          *
1489          * We do not need to allocate a new reservation window if we come here
1490          * at the beginning with a goal and the goal is inside the window, or
1491          * we don't have a goal but already have a reservation window.
1492          * then we could go to allocate from the reservation window directly.
1493          */
1494         while (1) {
1495                 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1496                         !goal_in_my_reservation(&my_rsv->rsv_window,
1497                                                 grp_goal, group, sb)) {
1498                         if (my_rsv->rsv_goal_size < *count)
1499                                 my_rsv->rsv_goal_size = *count;
1500                         ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1501                                                         group, bitmap_bh);
1502                         if (ret < 0)
1503                                 break;                  /* failed */
1504
1505                         if (!goal_in_my_reservation(&my_rsv->rsv_window,
1506                                                         grp_goal, group, sb))
1507                                 grp_goal = -1;
1508                 } else if (grp_goal >= 0) {
1509                         int curr = my_rsv->rsv_end -
1510                                         (grp_goal + group_first_block) + 1;
1511
1512                         if (curr < *count)
1513                                 try_to_extend_reservation(my_rsv, sb,
1514                                                         *count - curr);
1515                 }
1516
1517                 if ((my_rsv->rsv_start > group_last_block) ||
1518                                 (my_rsv->rsv_end < group_first_block)) {
1519                         rsv_window_dump(&EXT4_SB(sb)->s_rsv_window_root, 1);
1520                         BUG();
1521                 }
1522                 ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
1523                                            grp_goal, &num, &my_rsv->rsv_window);
1524                 if (ret >= 0) {
1525                         my_rsv->rsv_alloc_hit += num;
1526                         *count = num;
1527                         break;                          /* succeed */
1528                 }
1529                 num = *count;
1530         }
1531 out:
1532         if (ret >= 0) {
1533                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1534                                         "bitmap block");
1535                 fatal = ext4_journal_dirty_metadata(handle, bitmap_bh);
1536                 if (fatal) {
1537                         *errp = fatal;
1538                         return -1;
1539                 }
1540                 return ret;
1541         }
1542
1543         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1544         ext4_journal_release_buffer(handle, bitmap_bh);
1545         return ret;
1546 }
1547
1548 /**
1549  * ext4_has_free_blocks()
1550  * @sbi:                in-core super block structure.
1551  *
1552  * Check if filesystem has at least 1 free block available for allocation.
1553  */
1554 static int ext4_has_free_blocks(struct ext4_sb_info *sbi)
1555 {
1556         ext4_fsblk_t free_blocks, root_blocks;
1557
1558         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1559         root_blocks = ext4_r_blocks_count(sbi->s_es);
1560         if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1561                 sbi->s_resuid != current->fsuid &&
1562                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1563                 return 0;
1564         }
1565         return 1;
1566 }
1567
1568 /**
1569  * ext4_should_retry_alloc()
1570  * @sb:                 super block
1571  * @retries             number of attemps has been made
1572  *
1573  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
1574  * it is profitable to retry the operation, this function will wait
1575  * for the current or commiting transaction to complete, and then
1576  * return TRUE.
1577  *
1578  * if the total number of retries exceed three times, return FALSE.
1579  */
1580 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
1581 {
1582         if (!ext4_has_free_blocks(EXT4_SB(sb)) || (*retries)++ > 3)
1583                 return 0;
1584
1585         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1586
1587         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
1588 }
1589
1590 /**
1591  * ext4_new_blocks_old() -- core block(s) allocation function
1592  * @handle:             handle to this transaction
1593  * @inode:              file inode
1594  * @goal:               given target block(filesystem wide)
1595  * @count:              target number of blocks to allocate
1596  * @errp:               error code
1597  *
1598  * ext4_new_blocks uses a goal block to assist allocation.  It tries to
1599  * allocate block(s) from the block group contains the goal block first. If that
1600  * fails, it will try to allocate block(s) from other block groups without
1601  * any specific goal block.
1602  *
1603  */
1604 ext4_fsblk_t ext4_new_blocks_old(handle_t *handle, struct inode *inode,
1605                         ext4_fsblk_t goal, unsigned long *count, int *errp)
1606 {
1607         struct buffer_head *bitmap_bh = NULL;
1608         struct buffer_head *gdp_bh;
1609         ext4_group_t group_no;
1610         ext4_group_t goal_group;
1611         ext4_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1612         ext4_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1613         ext4_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1614         ext4_group_t bgi;                       /* blockgroup iteration index */
1615         int fatal = 0, err;
1616         int performed_allocation = 0;
1617         ext4_grpblk_t free_blocks;      /* number of free blocks in a group */
1618         struct super_block *sb;
1619         struct ext4_group_desc *gdp;
1620         struct ext4_super_block *es;
1621         struct ext4_sb_info *sbi;
1622         struct ext4_reserve_window_node *my_rsv = NULL;
1623         struct ext4_block_alloc_info *block_i;
1624         unsigned short windowsz = 0;
1625         ext4_group_t ngroups;
1626         unsigned long num = *count;
1627
1628         *errp = -ENOSPC;
1629         sb = inode->i_sb;
1630         if (!sb) {
1631                 printk("ext4_new_block: nonexistent device");
1632                 return 0;
1633         }
1634
1635         /*
1636          * Check quota for allocation of this block.
1637          */
1638         if (DQUOT_ALLOC_BLOCK(inode, num)) {
1639                 *errp = -EDQUOT;
1640                 return 0;
1641         }
1642
1643         sbi = EXT4_SB(sb);
1644         es = EXT4_SB(sb)->s_es;
1645         ext4_debug("goal=%llu.\n", goal);
1646         /*
1647          * Allocate a block from reservation only when
1648          * filesystem is mounted with reservation(default,-o reservation), and
1649          * it's a regular file, and
1650          * the desired window size is greater than 0 (One could use ioctl
1651          * command EXT4_IOC_SETRSVSZ to set the window size to 0 to turn off
1652          * reservation on that particular file)
1653          */
1654         block_i = EXT4_I(inode)->i_block_alloc_info;
1655         if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1656                 my_rsv = &block_i->rsv_window_node;
1657
1658         if (!ext4_has_free_blocks(sbi)) {
1659                 *errp = -ENOSPC;
1660                 goto out;
1661         }
1662
1663         /*
1664          * First, test whether the goal block is free.
1665          */
1666         if (goal < le32_to_cpu(es->s_first_data_block) ||
1667             goal >= ext4_blocks_count(es))
1668                 goal = le32_to_cpu(es->s_first_data_block);
1669         ext4_get_group_no_and_offset(sb, goal, &group_no, &grp_target_blk);
1670         goal_group = group_no;
1671 retry_alloc:
1672         gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
1673         if (!gdp)
1674                 goto io_error;
1675
1676         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1677         /*
1678          * if there is not enough free blocks to make a new resevation
1679          * turn off reservation for this allocation
1680          */
1681         if (my_rsv && (free_blocks < windowsz)
1682                 && (rsv_is_empty(&my_rsv->rsv_window)))
1683                 my_rsv = NULL;
1684
1685         if (free_blocks > 0) {
1686                 bitmap_bh = read_block_bitmap(sb, group_no);
1687                 if (!bitmap_bh)
1688                         goto io_error;
1689                 grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
1690                                         group_no, bitmap_bh, grp_target_blk,
1691                                         my_rsv, &num, &fatal);
1692                 if (fatal)
1693                         goto out;
1694                 if (grp_alloc_blk >= 0)
1695                         goto allocated;
1696         }
1697
1698         ngroups = EXT4_SB(sb)->s_groups_count;
1699         smp_rmb();
1700
1701         /*
1702          * Now search the rest of the groups.  We assume that
1703          * group_no and gdp correctly point to the last group visited.
1704          */
1705         for (bgi = 0; bgi < ngroups; bgi++) {
1706                 group_no++;
1707                 if (group_no >= ngroups)
1708                         group_no = 0;
1709                 gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
1710                 if (!gdp)
1711                         goto io_error;
1712                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1713                 /*
1714                  * skip this group if the number of
1715                  * free blocks is less than half of the reservation
1716                  * window size.
1717                  */
1718                 if (free_blocks <= (windowsz/2))
1719                         continue;
1720
1721                 brelse(bitmap_bh);
1722                 bitmap_bh = read_block_bitmap(sb, group_no);
1723                 if (!bitmap_bh)
1724                         goto io_error;
1725                 /*
1726                  * try to allocate block(s) from this group, without a goal(-1).
1727                  */
1728                 grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
1729                                         group_no, bitmap_bh, -1, my_rsv,
1730                                         &num, &fatal);
1731                 if (fatal)
1732                         goto out;
1733                 if (grp_alloc_blk >= 0)
1734                         goto allocated;
1735         }
1736         /*
1737          * We may end up a bogus ealier ENOSPC error due to
1738          * filesystem is "full" of reservations, but
1739          * there maybe indeed free blocks avaliable on disk
1740          * In this case, we just forget about the reservations
1741          * just do block allocation as without reservations.
1742          */
1743         if (my_rsv) {
1744                 my_rsv = NULL;
1745                 windowsz = 0;
1746                 group_no = goal_group;
1747                 goto retry_alloc;
1748         }
1749         /* No space left on the device */
1750         *errp = -ENOSPC;
1751         goto out;
1752
1753 allocated:
1754
1755         ext4_debug("using block group %lu(%d)\n",
1756                         group_no, gdp->bg_free_blocks_count);
1757
1758         BUFFER_TRACE(gdp_bh, "get_write_access");
1759         fatal = ext4_journal_get_write_access(handle, gdp_bh);
1760         if (fatal)
1761                 goto out;
1762
1763         ret_block = grp_alloc_blk + ext4_group_first_block_no(sb, group_no);
1764
1765         if (in_range(ext4_block_bitmap(sb, gdp), ret_block, num) ||
1766             in_range(ext4_inode_bitmap(sb, gdp), ret_block, num) ||
1767             in_range(ret_block, ext4_inode_table(sb, gdp),
1768                      EXT4_SB(sb)->s_itb_per_group) ||
1769             in_range(ret_block + num - 1, ext4_inode_table(sb, gdp),
1770                      EXT4_SB(sb)->s_itb_per_group)) {
1771                 ext4_error(sb, "ext4_new_block",
1772                             "Allocating block in system zone - "
1773                             "blocks from %llu, length %lu",
1774                              ret_block, num);
1775                 goto out;
1776         }
1777
1778         performed_allocation = 1;
1779
1780 #ifdef CONFIG_JBD2_DEBUG
1781         {
1782                 struct buffer_head *debug_bh;
1783
1784                 /* Record bitmap buffer state in the newly allocated block */
1785                 debug_bh = sb_find_get_block(sb, ret_block);
1786                 if (debug_bh) {
1787                         BUFFER_TRACE(debug_bh, "state when allocated");
1788                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1789                         brelse(debug_bh);
1790                 }
1791         }
1792         jbd_lock_bh_state(bitmap_bh);
1793         spin_lock(sb_bgl_lock(sbi, group_no));
1794         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1795                 int i;
1796
1797                 for (i = 0; i < num; i++) {
1798                         if (ext4_test_bit(grp_alloc_blk+i,
1799                                         bh2jh(bitmap_bh)->b_committed_data)) {
1800                                 printk("%s: block was unexpectedly set in "
1801                                         "b_committed_data\n", __FUNCTION__);
1802                         }
1803                 }
1804         }
1805         ext4_debug("found bit %d\n", grp_alloc_blk);
1806         spin_unlock(sb_bgl_lock(sbi, group_no));
1807         jbd_unlock_bh_state(bitmap_bh);
1808 #endif
1809
1810         if (ret_block + num - 1 >= ext4_blocks_count(es)) {
1811                 ext4_error(sb, "ext4_new_block",
1812                             "block(%llu) >= blocks count(%llu) - "
1813                             "block_group = %lu, es == %p ", ret_block,
1814                         ext4_blocks_count(es), group_no, es);
1815                 goto out;
1816         }
1817
1818         /*
1819          * It is up to the caller to add the new buffer to a journal
1820          * list of some description.  We don't know in advance whether
1821          * the caller wants to use it as metadata or data.
1822          */
1823         spin_lock(sb_bgl_lock(sbi, group_no));
1824         if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))
1825                 gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
1826         gdp->bg_free_blocks_count =
1827                         cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)-num);
1828         gdp->bg_checksum = ext4_group_desc_csum(sbi, group_no, gdp);
1829         spin_unlock(sb_bgl_lock(sbi, group_no));
1830         percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1831
1832         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1833         err = ext4_journal_dirty_metadata(handle, gdp_bh);
1834         if (!fatal)
1835                 fatal = err;
1836
1837         sb->s_dirt = 1;
1838         if (fatal)
1839                 goto out;
1840
1841         *errp = 0;
1842         brelse(bitmap_bh);
1843         DQUOT_FREE_BLOCK(inode, *count-num);
1844         *count = num;
1845         return ret_block;
1846
1847 io_error:
1848         *errp = -EIO;
1849 out:
1850         if (fatal) {
1851                 *errp = fatal;
1852                 ext4_std_error(sb, fatal);
1853         }
1854         /*
1855          * Undo the block allocation
1856          */
1857         if (!performed_allocation)
1858                 DQUOT_FREE_BLOCK(inode, *count);
1859         brelse(bitmap_bh);
1860         return 0;
1861 }
1862
1863 ext4_fsblk_t ext4_new_block(handle_t *handle, struct inode *inode,
1864                 ext4_fsblk_t goal, int *errp)
1865 {
1866         struct ext4_allocation_request ar;
1867         ext4_fsblk_t ret;
1868
1869         if (!test_opt(inode->i_sb, MBALLOC)) {
1870                 unsigned long count = 1;
1871                 ret = ext4_new_blocks_old(handle, inode, goal, &count, errp);
1872                 return ret;
1873         }
1874
1875         memset(&ar, 0, sizeof(ar));
1876         ar.inode = inode;
1877         ar.goal = goal;
1878         ar.len = 1;
1879         ret = ext4_mb_new_blocks(handle, &ar, errp);
1880         return ret;
1881 }
1882
1883 ext4_fsblk_t ext4_new_blocks(handle_t *handle, struct inode *inode,
1884                 ext4_fsblk_t goal, unsigned long *count, int *errp)
1885 {
1886         struct ext4_allocation_request ar;
1887         ext4_fsblk_t ret;
1888
1889         if (!test_opt(inode->i_sb, MBALLOC)) {
1890                 ret = ext4_new_blocks_old(handle, inode, goal, count, errp);
1891                 return ret;
1892         }
1893
1894         memset(&ar, 0, sizeof(ar));
1895         ar.inode = inode;
1896         ar.goal = goal;
1897         ar.len = *count;
1898         ret = ext4_mb_new_blocks(handle, &ar, errp);
1899         *count = ar.len;
1900         return ret;
1901 }
1902
1903
1904 /**
1905  * ext4_count_free_blocks() -- count filesystem free blocks
1906  * @sb:         superblock
1907  *
1908  * Adds up the number of free blocks from each block group.
1909  */
1910 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
1911 {
1912         ext4_fsblk_t desc_count;
1913         struct ext4_group_desc *gdp;
1914         ext4_group_t i;
1915         ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
1916 #ifdef EXT4FS_DEBUG
1917         struct ext4_super_block *es;
1918         ext4_fsblk_t bitmap_count;
1919         unsigned long x;
1920         struct buffer_head *bitmap_bh = NULL;
1921
1922         es = EXT4_SB(sb)->s_es;
1923         desc_count = 0;
1924         bitmap_count = 0;
1925         gdp = NULL;
1926
1927         smp_rmb();
1928         for (i = 0; i < ngroups; i++) {
1929                 gdp = ext4_get_group_desc(sb, i, NULL);
1930                 if (!gdp)
1931                         continue;
1932                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1933                 brelse(bitmap_bh);
1934                 bitmap_bh = read_block_bitmap(sb, i);
1935                 if (bitmap_bh == NULL)
1936                         continue;
1937
1938                 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
1939                 printk(KERN_DEBUG "group %lu: stored = %d, counted = %lu\n",
1940                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1941                 bitmap_count += x;
1942         }
1943         brelse(bitmap_bh);
1944         printk("ext4_count_free_blocks: stored = %llu"
1945                 ", computed = %llu, %llu\n",
1946                 ext4_free_blocks_count(es),
1947                 desc_count, bitmap_count);
1948         return bitmap_count;
1949 #else
1950         desc_count = 0;
1951         smp_rmb();
1952         for (i = 0; i < ngroups; i++) {
1953                 gdp = ext4_get_group_desc(sb, i, NULL);
1954                 if (!gdp)
1955                         continue;
1956                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1957         }
1958
1959         return desc_count;
1960 #endif
1961 }
1962
1963 static inline int test_root(ext4_group_t a, int b)
1964 {
1965         int num = b;
1966
1967         while (a > num)
1968                 num *= b;
1969         return num == a;
1970 }
1971
1972 static int ext4_group_sparse(ext4_group_t group)
1973 {
1974         if (group <= 1)
1975                 return 1;
1976         if (!(group & 1))
1977                 return 0;
1978         return (test_root(group, 7) || test_root(group, 5) ||
1979                 test_root(group, 3));
1980 }
1981
1982 /**
1983  *      ext4_bg_has_super - number of blocks used by the superblock in group
1984  *      @sb: superblock for filesystem
1985  *      @group: group number to check
1986  *
1987  *      Return the number of blocks used by the superblock (primary or backup)
1988  *      in this group.  Currently this will be only 0 or 1.
1989  */
1990 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
1991 {
1992         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
1993                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1994                         !ext4_group_sparse(group))
1995                 return 0;
1996         return 1;
1997 }
1998
1999 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
2000                                         ext4_group_t group)
2001 {
2002         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
2003         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
2004         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
2005
2006         if (group == first || group == first + 1 || group == last)
2007                 return 1;
2008         return 0;
2009 }
2010
2011 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
2012                                         ext4_group_t group)
2013 {
2014         return ext4_bg_has_super(sb, group) ? EXT4_SB(sb)->s_gdb_count : 0;
2015 }
2016
2017 /**
2018  *      ext4_bg_num_gdb - number of blocks used by the group table in group
2019  *      @sb: superblock for filesystem
2020  *      @group: group number to check
2021  *
2022  *      Return the number of blocks used by the group descriptor table
2023  *      (primary or backup) in this group.  In the future there may be a
2024  *      different number of descriptor blocks in each group.
2025  */
2026 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
2027 {
2028         unsigned long first_meta_bg =
2029                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
2030         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
2031
2032         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
2033                         metagroup < first_meta_bg)
2034                 return ext4_bg_num_gdb_nometa(sb,group);
2035
2036         return ext4_bg_num_gdb_meta(sb,group);
2037
2038 }