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balloc.c
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1 /*
2  * linux/fs/ext2/balloc.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card ([email protected])
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  * Enhanced block allocation by Stephen Tweedie ([email protected]), 1993
10  * Big-endian to little-endian byte-swapping/bitmaps by
11  * David S. Miller ([email protected]), 1995
12  */
13 
14 #include "ext2.h"
15 #include <linux/quotaops.h>
16 #include <linux/slab.h>
17 #include <linux/sched.h>
18 #include <linux/buffer_head.h>
19 #include <linux/capability.h>
20 
21 /*
22  * balloc.c contains the blocks allocation and deallocation routines
23  */
24 
25 /*
26  * The free blocks are managed by bitmaps. A file system contains several
27  * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
28  * block for inodes, N blocks for the inode table and data blocks.
29  *
30  * The file system contains group descriptors which are located after the
31  * super block. Each descriptor contains the number of the bitmap block and
32  * the free blocks count in the block. The descriptors are loaded in memory
33  * when a file system is mounted (see ext2_fill_super).
34  */
35 
36 
37 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
38 
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 
73 static 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 {
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 
109 err_out:
110  ext2_error(sb, __func__,
111  "Invalid block bitmap - "
112  "block_group = %d, block = %lu",
113  block_group, bitmap_blk);
114  return 0;
115 }
116 
117 /*
118  * Read the bitmap for a given block_group,and validate the
119  * bits for block/inode/inode tables are set in the bitmaps
120  *
121  * Return buffer_head on success or NULL in case of failure.
122  */
123 static struct buffer_head *
124 read_block_bitmap(struct super_block *sb, unsigned int block_group)
125 {
126  struct ext2_group_desc * desc;
127  struct buffer_head * bh = NULL;
128  ext2_fsblk_t bitmap_blk;
129 
130  desc = ext2_get_group_desc(sb, block_group, NULL);
131  if (!desc)
132  return NULL;
133  bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
134  bh = sb_getblk(sb, bitmap_blk);
135  if (unlikely(!bh)) {
136  ext2_error(sb, __func__,
137  "Cannot read block bitmap - "
138  "block_group = %d, block_bitmap = %u",
139  block_group, le32_to_cpu(desc->bg_block_bitmap));
140  return NULL;
141  }
142  if (likely(bh_uptodate_or_lock(bh)))
143  return bh;
144 
145  if (bh_submit_read(bh) < 0) {
146  brelse(bh);
147  ext2_error(sb, __func__,
148  "Cannot read block bitmap - "
149  "block_group = %d, block_bitmap = %u",
150  block_group, le32_to_cpu(desc->bg_block_bitmap));
151  return NULL;
152  }
153 
154  ext2_valid_block_bitmap(sb, desc, block_group, bh);
155  /*
156  * file system mounted not to panic on error, continue with corrupt
157  * bitmap
158  */
159  return bh;
160 }
161 
162 static void release_blocks(struct super_block *sb, int count)
163 {
164  if (count) {
165  struct ext2_sb_info *sbi = EXT2_SB(sb);
166 
167  percpu_counter_add(&sbi->s_freeblocks_counter, count);
168  }
169 }
170 
171 static void group_adjust_blocks(struct super_block *sb, int group_no,
172  struct ext2_group_desc *desc, struct buffer_head *bh, int count)
173 {
174  if (count) {
175  struct ext2_sb_info *sbi = EXT2_SB(sb);
176  unsigned free_blocks;
177 
178  spin_lock(sb_bgl_lock(sbi, group_no));
179  free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
180  desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
181  spin_unlock(sb_bgl_lock(sbi, group_no));
182  mark_buffer_dirty(bh);
183  }
184 }
185 
186 /*
187  * The reservation window structure operations
188  * --------------------------------------------
189  * Operations include:
190  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
191  *
192  * We use a red-black tree to represent per-filesystem reservation
193  * windows.
194  *
195  */
196 
207 #if 1
208 static void __rsv_window_dump(struct rb_root *root, int verbose,
209  const char *fn)
210 {
211  struct rb_node *n;
213  int bad;
214 
215 restart:
216  n = rb_first(root);
217  bad = 0;
218  prev = NULL;
219 
220  printk("Block Allocation Reservation Windows Map (%s):\n", fn);
221  while (n) {
222  rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
223  if (verbose)
224  printk("reservation window 0x%p "
225  "start: %lu, end: %lu\n",
226  rsv, rsv->rsv_start, rsv->rsv_end);
227  if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
228  printk("Bad reservation %p (start >= end)\n",
229  rsv);
230  bad = 1;
231  }
232  if (prev && prev->rsv_end >= rsv->rsv_start) {
233  printk("Bad reservation %p (prev->end >= start)\n",
234  rsv);
235  bad = 1;
236  }
237  if (bad) {
238  if (!verbose) {
239  printk("Restarting reservation walk in verbose mode\n");
240  verbose = 1;
241  goto restart;
242  }
243  }
244  n = rb_next(n);
245  prev = rsv;
246  }
247  printk("Window map complete.\n");
248  BUG_ON(bad);
249 }
250 #define rsv_window_dump(root, verbose) \
251  __rsv_window_dump((root), (verbose), __func__)
252 #else
253 #define rsv_window_dump(root, verbose) do {} while (0)
254 #endif
255 
272 static int
273 goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
274  unsigned int group, struct super_block * sb)
275 {
276  ext2_fsblk_t group_first_block, group_last_block;
277 
278  group_first_block = ext2_group_first_block_no(sb, group);
279  group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
280 
281  if ((rsv->_rsv_start > group_last_block) ||
282  (rsv->_rsv_end < group_first_block))
283  return 0;
284  if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
285  || (grp_goal + group_first_block > rsv->_rsv_end)))
286  return 0;
287  return 1;
288 }
289 
299 static struct ext2_reserve_window_node *
300 search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
301 {
302  struct rb_node *n = root->rb_node;
304 
305  if (!n)
306  return NULL;
307 
308  do {
309  rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
310 
311  if (goal < rsv->rsv_start)
312  n = n->rb_left;
313  else if (goal > rsv->rsv_end)
314  n = n->rb_right;
315  else
316  return rsv;
317  } while (n);
318  /*
319  * We've fallen off the end of the tree: the goal wasn't inside
320  * any particular node. OK, the previous node must be to one
321  * side of the interval containing the goal. If it's the RHS,
322  * we need to back up one.
323  */
324  if (rsv->rsv_start > goal) {
325  n = rb_prev(&rsv->rsv_node);
326  rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
327  }
328  return rsv;
329 }
330 
331 /*
332  * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
333  * @sb: super block
334  * @rsv: reservation window to add
335  *
336  * Must be called with rsv_lock held.
337  */
339  struct ext2_reserve_window_node *rsv)
340 {
341  struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
342  struct rb_node *node = &rsv->rsv_node;
343  ext2_fsblk_t start = rsv->rsv_start;
344 
345  struct rb_node ** p = &root->rb_node;
346  struct rb_node * parent = NULL;
347  struct ext2_reserve_window_node *this;
348 
349  while (*p)
350  {
351  parent = *p;
352  this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
353 
354  if (start < this->rsv_start)
355  p = &(*p)->rb_left;
356  else if (start > this->rsv_end)
357  p = &(*p)->rb_right;
358  else {
359  rsv_window_dump(root, 1);
360  BUG();
361  }
362  }
363 
364  rb_link_node(node, parent, p);
365  rb_insert_color(node, root);
366 }
367 
377 static void rsv_window_remove(struct super_block *sb,
378  struct ext2_reserve_window_node *rsv)
379 {
380  rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
381  rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
382  rsv->rsv_alloc_hit = 0;
383  rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
384 }
385 
386 /*
387  * rsv_is_empty() -- Check if the reservation window is allocated.
388  * @rsv: given reservation window to check
389  *
390  * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
391  */
392 static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
393 {
394  /* a valid reservation end block could not be 0 */
396 }
397 
420 {
421  struct ext2_inode_info *ei = EXT2_I(inode);
422  struct ext2_block_alloc_info *block_i;
423  struct super_block *sb = inode->i_sb;
424 
425  block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
426  if (block_i) {
427  struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
428 
429  rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
430  rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
431 
432  /*
433  * if filesystem is mounted with NORESERVATION, the goal
434  * reservation window size is set to zero to indicate
435  * block reservation is off
436  */
437  if (!test_opt(sb, RESERVATION))
438  rsv->rsv_goal_size = 0;
439  else
441  rsv->rsv_alloc_hit = 0;
442  block_i->last_alloc_logical_block = 0;
443  block_i->last_alloc_physical_block = 0;
444  }
445  ei->i_block_alloc_info = block_i;
446 }
447 
461 {
462  struct ext2_inode_info *ei = EXT2_I(inode);
463  struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
465  spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
466 
467  if (!block_i)
468  return;
469 
470  rsv = &block_i->rsv_window_node;
471  if (!rsv_is_empty(&rsv->rsv_window)) {
472  spin_lock(rsv_lock);
473  if (!rsv_is_empty(&rsv->rsv_window))
474  rsv_window_remove(inode->i_sb, rsv);
475  spin_unlock(rsv_lock);
476  }
477 }
478 
485 void ext2_free_blocks (struct inode * inode, unsigned long block,
486  unsigned long count)
487 {
488  struct buffer_head *bitmap_bh = NULL;
489  struct buffer_head * bh2;
490  unsigned long block_group;
491  unsigned long bit;
492  unsigned long i;
493  unsigned long overflow;
494  struct super_block * sb = inode->i_sb;
495  struct ext2_sb_info * sbi = EXT2_SB(sb);
496  struct ext2_group_desc * desc;
497  struct ext2_super_block * es = sbi->s_es;
498  unsigned freed = 0, group_freed;
499 
500  if (block < le32_to_cpu(es->s_first_data_block) ||
501  block + count < block ||
502  block + count > le32_to_cpu(es->s_blocks_count)) {
503  ext2_error (sb, "ext2_free_blocks",
504  "Freeing blocks not in datazone - "
505  "block = %lu, count = %lu", block, count);
506  goto error_return;
507  }
508 
509  ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
510 
511 do_more:
512  overflow = 0;
513  block_group = (block - le32_to_cpu(es->s_first_data_block)) /
515  bit = (block - le32_to_cpu(es->s_first_data_block)) %
517  /*
518  * Check to see if we are freeing blocks across a group
519  * boundary.
520  */
521  if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
522  overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
523  count -= overflow;
524  }
525  brelse(bitmap_bh);
526  bitmap_bh = read_block_bitmap(sb, block_group);
527  if (!bitmap_bh)
528  goto error_return;
529 
530  desc = ext2_get_group_desc (sb, block_group, &bh2);
531  if (!desc)
532  goto error_return;
533 
534  if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
535  in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
536  in_range (block, le32_to_cpu(desc->bg_inode_table),
537  sbi->s_itb_per_group) ||
538  in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
539  sbi->s_itb_per_group)) {
540  ext2_error (sb, "ext2_free_blocks",
541  "Freeing blocks in system zones - "
542  "Block = %lu, count = %lu",
543  block, count);
544  goto error_return;
545  }
546 
547  for (i = 0, group_freed = 0; i < count; i++) {
548  if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
549  bit + i, bitmap_bh->b_data)) {
550  ext2_error(sb, __func__,
551  "bit already cleared for block %lu", block + i);
552  } else {
553  group_freed++;
554  }
555  }
556 
557  mark_buffer_dirty(bitmap_bh);
558  if (sb->s_flags & MS_SYNCHRONOUS)
559  sync_dirty_buffer(bitmap_bh);
560 
561  group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
562  freed += group_freed;
563 
564  if (overflow) {
565  block += count;
566  count = overflow;
567  goto do_more;
568  }
569 error_return:
570  brelse(bitmap_bh);
571  release_blocks(sb, freed);
572  dquot_free_block_nodirty(inode, freed);
573 }
574 
584 static ext2_grpblk_t
585 bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
586  ext2_grpblk_t maxblocks)
587 {
589 
590  next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
591  if (next >= maxblocks)
592  return -1;
593  return next;
594 }
595 
608 static ext2_grpblk_t
609 find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
610 {
612  char *p, *r;
613 
614  if (start > 0) {
615  /*
616  * The goal was occupied; search forward for a free
617  * block within the next XX blocks.
618  *
619  * end_goal is more or less random, but it has to be
620  * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
621  * next 64-bit boundary is simple..
622  */
623  ext2_grpblk_t end_goal = (start + 63) & ~63;
624  if (end_goal > maxblocks)
625  end_goal = maxblocks;
626  here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
627  if (here < end_goal)
628  return here;
629  ext2_debug("Bit not found near goal\n");
630  }
631 
632  here = start;
633  if (here < 0)
634  here = 0;
635 
636  p = ((char *)bh->b_data) + (here >> 3);
637  r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
638  next = (r - ((char *)bh->b_data)) << 3;
639 
640  if (next < maxblocks && next >= here)
641  return next;
642 
643  here = bitmap_search_next_usable_block(here, bh, maxblocks);
644  return here;
645 }
646 
669 static int
670 ext2_try_to_allocate(struct super_block *sb, int group,
671  struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
672  unsigned long *count,
673  struct ext2_reserve_window *my_rsv)
674 {
675  ext2_fsblk_t group_first_block;
677  unsigned long num = 0;
678 
679  /* we do allocation within the reservation window if we have a window */
680  if (my_rsv) {
681  group_first_block = ext2_group_first_block_no(sb, group);
682  if (my_rsv->_rsv_start >= group_first_block)
683  start = my_rsv->_rsv_start - group_first_block;
684  else
685  /* reservation window cross group boundary */
686  start = 0;
687  end = my_rsv->_rsv_end - group_first_block + 1;
688  if (end > EXT2_BLOCKS_PER_GROUP(sb))
689  /* reservation window crosses group boundary */
690  end = EXT2_BLOCKS_PER_GROUP(sb);
691  if ((start <= grp_goal) && (grp_goal < end))
692  start = grp_goal;
693  else
694  grp_goal = -1;
695  } else {
696  if (grp_goal > 0)
697  start = grp_goal;
698  else
699  start = 0;
700  end = EXT2_BLOCKS_PER_GROUP(sb);
701  }
702 
703  BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
704 
705 repeat:
706  if (grp_goal < 0) {
707  grp_goal = find_next_usable_block(start, bitmap_bh, end);
708  if (grp_goal < 0)
709  goto fail_access;
710  if (!my_rsv) {
711  int i;
712 
713  for (i = 0; i < 7 && grp_goal > start &&
714  !ext2_test_bit(grp_goal - 1,
715  bitmap_bh->b_data);
716  i++, grp_goal--)
717  ;
718  }
719  }
720  start = grp_goal;
721 
722  if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
723  bitmap_bh->b_data)) {
724  /*
725  * The block was allocated by another thread, or it was
726  * allocated and then freed by another thread
727  */
728  start++;
729  grp_goal++;
730  if (start >= end)
731  goto fail_access;
732  goto repeat;
733  }
734  num++;
735  grp_goal++;
736  while (num < *count && grp_goal < end
737  && !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
738  grp_goal, bitmap_bh->b_data)) {
739  num++;
740  grp_goal++;
741  }
742  *count = num;
743  return grp_goal - num;
744 fail_access:
745  *count = num;
746  return -1;
747 }
748 
782 static int find_next_reservable_window(
783  struct ext2_reserve_window_node *search_head,
784  struct ext2_reserve_window_node *my_rsv,
785  struct super_block * sb,
787  ext2_fsblk_t last_block)
788 {
789  struct rb_node *next;
792  int size = my_rsv->rsv_goal_size;
793 
794  /* TODO: make the start of the reservation window byte-aligned */
795  /* cur = *start_block & ~7;*/
796  cur = start_block;
797  rsv = search_head;
798  if (!rsv)
799  return -1;
800 
801  while (1) {
802  if (cur <= rsv->rsv_end)
803  cur = rsv->rsv_end + 1;
804 
805  /* TODO?
806  * in the case we could not find a reservable space
807  * that is what is expected, during the re-search, we could
808  * remember what's the largest reservable space we could have
809  * and return that one.
810  *
811  * For now it will fail if we could not find the reservable
812  * space with expected-size (or more)...
813  */
814  if (cur > last_block)
815  return -1; /* fail */
816 
817  prev = rsv;
818  next = rb_next(&rsv->rsv_node);
819  rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
820 
821  /*
822  * Reached the last reservation, we can just append to the
823  * previous one.
824  */
825  if (!next)
826  break;
827 
828  if (cur + size <= rsv->rsv_start) {
829  /*
830  * Found a reserveable space big enough. We could
831  * have a reservation across the group boundary here
832  */
833  break;
834  }
835  }
836  /*
837  * we come here either :
838  * when we reach the end of the whole list,
839  * and there is empty reservable space after last entry in the list.
840  * append it to the end of the list.
841  *
842  * or we found one reservable space in the middle of the list,
843  * return the reservation window that we could append to.
844  * succeed.
845  */
846 
847  if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
848  rsv_window_remove(sb, my_rsv);
849 
850  /*
851  * Let's book the whole available window for now. We will check the
852  * disk bitmap later and then, if there are free blocks then we adjust
853  * the window size if it's larger than requested.
854  * Otherwise, we will remove this node from the tree next time
855  * call find_next_reservable_window.
856  */
857  my_rsv->rsv_start = cur;
858  my_rsv->rsv_end = cur + size - 1;
859  my_rsv->rsv_alloc_hit = 0;
860 
861  if (prev != my_rsv)
862  ext2_rsv_window_add(sb, my_rsv);
863 
864  return 0;
865 }
866 
904 static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
905  ext2_grpblk_t grp_goal, struct super_block *sb,
906  unsigned int group, struct buffer_head *bitmap_bh)
907 {
908  struct ext2_reserve_window_node *search_head;
909  ext2_fsblk_t group_first_block, group_end_block, start_block;
910  ext2_grpblk_t first_free_block;
911  struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
912  unsigned long size;
913  int ret;
914  spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
915 
916  group_first_block = ext2_group_first_block_no(sb, group);
917  group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
918 
919  if (grp_goal < 0)
920  start_block = group_first_block;
921  else
922  start_block = grp_goal + group_first_block;
923 
924  size = my_rsv->rsv_goal_size;
925 
926  if (!rsv_is_empty(&my_rsv->rsv_window)) {
927  /*
928  * if the old reservation is cross group boundary
929  * and if the goal is inside the old reservation window,
930  * we will come here when we just failed to allocate from
931  * the first part of the window. We still have another part
932  * that belongs to the next group. In this case, there is no
933  * point to discard our window and try to allocate a new one
934  * in this group(which will fail). we should
935  * keep the reservation window, just simply move on.
936  *
937  * Maybe we could shift the start block of the reservation
938  * window to the first block of next group.
939  */
940 
941  if ((my_rsv->rsv_start <= group_end_block) &&
942  (my_rsv->rsv_end > group_end_block) &&
943  (start_block >= my_rsv->rsv_start))
944  return -1;
945 
946  if ((my_rsv->rsv_alloc_hit >
947  (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
948  /*
949  * if the previously allocation hit ratio is
950  * greater than 1/2, then we double the size of
951  * the reservation window the next time,
952  * otherwise we keep the same size window
953  */
954  size = size * 2;
955  if (size > EXT2_MAX_RESERVE_BLOCKS)
957  my_rsv->rsv_goal_size= size;
958  }
959  }
960 
961  spin_lock(rsv_lock);
962  /*
963  * shift the search start to the window near the goal block
964  */
965  search_head = search_reserve_window(fs_rsv_root, start_block);
966 
967  /*
968  * find_next_reservable_window() simply finds a reservable window
969  * inside the given range(start_block, group_end_block).
970  *
971  * To make sure the reservation window has a free bit inside it, we
972  * need to check the bitmap after we found a reservable window.
973  */
974 retry:
975  ret = find_next_reservable_window(search_head, my_rsv, sb,
976  start_block, group_end_block);
977 
978  if (ret == -1) {
979  if (!rsv_is_empty(&my_rsv->rsv_window))
980  rsv_window_remove(sb, my_rsv);
981  spin_unlock(rsv_lock);
982  return -1;
983  }
984 
985  /*
986  * On success, find_next_reservable_window() returns the
987  * reservation window where there is a reservable space after it.
988  * Before we reserve this reservable space, we need
989  * to make sure there is at least a free block inside this region.
990  *
991  * Search the first free bit on the block bitmap. Search starts from
992  * the start block of the reservable space we just found.
993  */
994  spin_unlock(rsv_lock);
995  first_free_block = bitmap_search_next_usable_block(
996  my_rsv->rsv_start - group_first_block,
997  bitmap_bh, group_end_block - group_first_block + 1);
998 
999  if (first_free_block < 0) {
1000  /*
1001  * no free block left on the bitmap, no point
1002  * to reserve the space. return failed.
1003  */
1004  spin_lock(rsv_lock);
1005  if (!rsv_is_empty(&my_rsv->rsv_window))
1006  rsv_window_remove(sb, my_rsv);
1007  spin_unlock(rsv_lock);
1008  return -1; /* failed */
1009  }
1010 
1011  start_block = first_free_block + group_first_block;
1012  /*
1013  * check if the first free block is within the
1014  * free space we just reserved
1015  */
1016  if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1017  return 0; /* success */
1018  /*
1019  * if the first free bit we found is out of the reservable space
1020  * continue search for next reservable space,
1021  * start from where the free block is,
1022  * we also shift the list head to where we stopped last time
1023  */
1024  search_head = my_rsv;
1025  spin_lock(rsv_lock);
1026  goto retry;
1027 }
1028 
1046 static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1047  struct super_block *sb, int size)
1048 {
1049  struct ext2_reserve_window_node *next_rsv;
1050  struct rb_node *next;
1051  spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1052 
1053  if (!spin_trylock(rsv_lock))
1054  return;
1055 
1056  next = rb_next(&my_rsv->rsv_node);
1057 
1058  if (!next)
1059  my_rsv->rsv_end += size;
1060  else {
1061  next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1062 
1063  if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1064  my_rsv->rsv_end += size;
1065  else
1066  my_rsv->rsv_end = next_rsv->rsv_start - 1;
1067  }
1068  spin_unlock(rsv_lock);
1069 }
1070 
1097 static ext2_grpblk_t
1098 ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1099  struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1100  struct ext2_reserve_window_node * my_rsv,
1101  unsigned long *count)
1102 {
1103  ext2_fsblk_t group_first_block, group_last_block;
1104  ext2_grpblk_t ret = 0;
1105  unsigned long num = *count;
1106 
1107  /*
1108  * we don't deal with reservation when
1109  * filesystem is mounted without reservation
1110  * or the file is not a regular file
1111  * or last attempt to allocate a block with reservation turned on failed
1112  */
1113  if (my_rsv == NULL) {
1114  return ext2_try_to_allocate(sb, group, bitmap_bh,
1115  grp_goal, count, NULL);
1116  }
1117  /*
1118  * grp_goal is a group relative block number (if there is a goal)
1119  * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1120  * first block is a filesystem wide block number
1121  * first block is the block number of the first block in this group
1122  */
1123  group_first_block = ext2_group_first_block_no(sb, group);
1124  group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
1125 
1126  /*
1127  * Basically we will allocate a new block from inode's reservation
1128  * window.
1129  *
1130  * We need to allocate a new reservation window, if:
1131  * a) inode does not have a reservation window; or
1132  * b) last attempt to allocate a block from existing reservation
1133  * failed; or
1134  * c) we come here with a goal and with a reservation window
1135  *
1136  * We do not need to allocate a new reservation window if we come here
1137  * at the beginning with a goal and the goal is inside the window, or
1138  * we don't have a goal but already have a reservation window.
1139  * then we could go to allocate from the reservation window directly.
1140  */
1141  while (1) {
1142  if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1143  !goal_in_my_reservation(&my_rsv->rsv_window,
1144  grp_goal, group, sb)) {
1145  if (my_rsv->rsv_goal_size < *count)
1146  my_rsv->rsv_goal_size = *count;
1147  ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1148  group, bitmap_bh);
1149  if (ret < 0)
1150  break; /* failed */
1151 
1152  if (!goal_in_my_reservation(&my_rsv->rsv_window,
1153  grp_goal, group, sb))
1154  grp_goal = -1;
1155  } else if (grp_goal >= 0) {
1156  int curr = my_rsv->rsv_end -
1157  (grp_goal + group_first_block) + 1;
1158 
1159  if (curr < *count)
1160  try_to_extend_reservation(my_rsv, sb,
1161  *count - curr);
1162  }
1163 
1164  if ((my_rsv->rsv_start > group_last_block) ||
1165  (my_rsv->rsv_end < group_first_block)) {
1166  rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1167  BUG();
1168  }
1169  ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1170  &num, &my_rsv->rsv_window);
1171  if (ret >= 0) {
1172  my_rsv->rsv_alloc_hit += num;
1173  *count = num;
1174  break; /* succeed */
1175  }
1176  num = *count;
1177  }
1178  return ret;
1179 }
1180 
1187 static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1188 {
1189  ext2_fsblk_t free_blocks, root_blocks;
1190 
1191  free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1192  root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1193  if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1194  !uid_eq(sbi->s_resuid, current_fsuid()) &&
1195  (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1196  !in_group_p (sbi->s_resgid))) {
1197  return 0;
1198  }
1199  return 1;
1200 }
1201 
1202 /*
1203  * ext2_new_blocks() -- core block(s) allocation function
1204  * @inode: file inode
1205  * @goal: given target block(filesystem wide)
1206  * @count: target number of blocks to allocate
1207  * @errp: error code
1208  *
1209  * ext2_new_blocks uses a goal block to assist allocation. If the goal is
1210  * free, or there is a free block within 32 blocks of the goal, that block
1211  * is allocated. Otherwise a forward search is made for a free block; within
1212  * each block group the search first looks for an entire free byte in the block
1213  * bitmap, and then for any free bit if that fails.
1214  * This function also updates quota and i_blocks field.
1215  */
1217  unsigned long *count, int *errp)
1218 {
1219  struct buffer_head *bitmap_bh = NULL;
1220  struct buffer_head *gdp_bh;
1221  int group_no;
1222  int goal_group;
1223  ext2_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1224  ext2_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1225  ext2_fsblk_t ret_block; /* filesyetem-wide allocated block */
1226  int bgi; /* blockgroup iteration index */
1227  int performed_allocation = 0;
1228  ext2_grpblk_t free_blocks; /* number of free blocks in a group */
1229  struct super_block *sb;
1230  struct ext2_group_desc *gdp;
1231  struct ext2_super_block *es;
1232  struct ext2_sb_info *sbi;
1233  struct ext2_reserve_window_node *my_rsv = NULL;
1234  struct ext2_block_alloc_info *block_i;
1235  unsigned short windowsz = 0;
1236  unsigned long ngroups;
1237  unsigned long num = *count;
1238  int ret;
1239 
1240  *errp = -ENOSPC;
1241  sb = inode->i_sb;
1242  if (!sb) {
1243  printk("ext2_new_blocks: nonexistent device");
1244  return 0;
1245  }
1246 
1247  /*
1248  * Check quota for allocation of this block.
1249  */
1250  ret = dquot_alloc_block(inode, num);
1251  if (ret) {
1252  *errp = ret;
1253  return 0;
1254  }
1255 
1256  sbi = EXT2_SB(sb);
1257  es = EXT2_SB(sb)->s_es;
1258  ext2_debug("goal=%lu.\n", goal);
1259  /*
1260  * Allocate a block from reservation only when
1261  * filesystem is mounted with reservation(default,-o reservation), and
1262  * it's a regular file, and
1263  * the desired window size is greater than 0 (One could use ioctl
1264  * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1265  * reservation on that particular file)
1266  */
1267  block_i = EXT2_I(inode)->i_block_alloc_info;
1268  if (block_i) {
1269  windowsz = block_i->rsv_window_node.rsv_goal_size;
1270  if (windowsz > 0)
1271  my_rsv = &block_i->rsv_window_node;
1272  }
1273 
1274  if (!ext2_has_free_blocks(sbi)) {
1275  *errp = -ENOSPC;
1276  goto out;
1277  }
1278 
1279  /*
1280  * First, test whether the goal block is free.
1281  */
1282  if (goal < le32_to_cpu(es->s_first_data_block) ||
1283  goal >= le32_to_cpu(es->s_blocks_count))
1284  goal = le32_to_cpu(es->s_first_data_block);
1285  group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1287  goal_group = group_no;
1288 retry_alloc:
1289  gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1290  if (!gdp)
1291  goto io_error;
1292 
1293  free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1294  /*
1295  * if there is not enough free blocks to make a new resevation
1296  * turn off reservation for this allocation
1297  */
1298  if (my_rsv && (free_blocks < windowsz)
1299  && (free_blocks > 0)
1300  && (rsv_is_empty(&my_rsv->rsv_window)))
1301  my_rsv = NULL;
1302 
1303  if (free_blocks > 0) {
1304  grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1305  EXT2_BLOCKS_PER_GROUP(sb));
1306  bitmap_bh = read_block_bitmap(sb, group_no);
1307  if (!bitmap_bh)
1308  goto io_error;
1309  grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1310  bitmap_bh, grp_target_blk,
1311  my_rsv, &num);
1312  if (grp_alloc_blk >= 0)
1313  goto allocated;
1314  }
1315 
1316  ngroups = EXT2_SB(sb)->s_groups_count;
1317  smp_rmb();
1318 
1319  /*
1320  * Now search the rest of the groups. We assume that
1321  * group_no and gdp correctly point to the last group visited.
1322  */
1323  for (bgi = 0; bgi < ngroups; bgi++) {
1324  group_no++;
1325  if (group_no >= ngroups)
1326  group_no = 0;
1327  gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1328  if (!gdp)
1329  goto io_error;
1330 
1331  free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1332  /*
1333  * skip this group (and avoid loading bitmap) if there
1334  * are no free blocks
1335  */
1336  if (!free_blocks)
1337  continue;
1338  /*
1339  * skip this group if the number of
1340  * free blocks is less than half of the reservation
1341  * window size.
1342  */
1343  if (my_rsv && (free_blocks <= (windowsz/2)))
1344  continue;
1345 
1346  brelse(bitmap_bh);
1347  bitmap_bh = read_block_bitmap(sb, group_no);
1348  if (!bitmap_bh)
1349  goto io_error;
1350  /*
1351  * try to allocate block(s) from this group, without a goal(-1).
1352  */
1353  grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1354  bitmap_bh, -1, my_rsv, &num);
1355  if (grp_alloc_blk >= 0)
1356  goto allocated;
1357  }
1358  /*
1359  * We may end up a bogus earlier ENOSPC error due to
1360  * filesystem is "full" of reservations, but
1361  * there maybe indeed free blocks available on disk
1362  * In this case, we just forget about the reservations
1363  * just do block allocation as without reservations.
1364  */
1365  if (my_rsv) {
1366  my_rsv = NULL;
1367  windowsz = 0;
1368  group_no = goal_group;
1369  goto retry_alloc;
1370  }
1371  /* No space left on the device */
1372  *errp = -ENOSPC;
1373  goto out;
1374 
1375 allocated:
1376 
1377  ext2_debug("using block group %d(%d)\n",
1378  group_no, gdp->bg_free_blocks_count);
1379 
1380  ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1381 
1382  if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1383  in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1384  in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1385  EXT2_SB(sb)->s_itb_per_group) ||
1386  in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1387  EXT2_SB(sb)->s_itb_per_group)) {
1388  ext2_error(sb, "ext2_new_blocks",
1389  "Allocating block in system zone - "
1390  "blocks from "E2FSBLK", length %lu",
1391  ret_block, num);
1392  /*
1393  * ext2_try_to_allocate marked the blocks we allocated as in
1394  * use. So we may want to selectively mark some of the blocks
1395  * as free
1396  */
1397  goto retry_alloc;
1398  }
1399 
1400  performed_allocation = 1;
1401 
1402  if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1403  ext2_error(sb, "ext2_new_blocks",
1404  "block("E2FSBLK") >= blocks count(%d) - "
1405  "block_group = %d, es == %p ", ret_block,
1406  le32_to_cpu(es->s_blocks_count), group_no, es);
1407  goto out;
1408  }
1409 
1410  group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1411  percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1412 
1413  mark_buffer_dirty(bitmap_bh);
1414  if (sb->s_flags & MS_SYNCHRONOUS)
1415  sync_dirty_buffer(bitmap_bh);
1416 
1417  *errp = 0;
1418  brelse(bitmap_bh);
1419  dquot_free_block_nodirty(inode, *count-num);
1420  mark_inode_dirty(inode);
1421  *count = num;
1422  return ret_block;
1423 
1424 io_error:
1425  *errp = -EIO;
1426 out:
1427  /*
1428  * Undo the block allocation
1429  */
1430  if (!performed_allocation) {
1431  dquot_free_block_nodirty(inode, *count);
1432  mark_inode_dirty(inode);
1433  }
1434  brelse(bitmap_bh);
1435  return 0;
1436 }
1437 
1438 ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1439 {
1440  unsigned long count = 1;
1441 
1442  return ext2_new_blocks(inode, goal, &count, errp);
1443 }
1444 
1445 #ifdef EXT2FS_DEBUG
1446 
1447 unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
1448 {
1449  return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
1450 }
1451 
1452 #endif /* EXT2FS_DEBUG */
1453 
1454 unsigned long ext2_count_free_blocks (struct super_block * sb)
1455 {
1456  struct ext2_group_desc * desc;
1457  unsigned long desc_count = 0;
1458  int i;
1459 #ifdef EXT2FS_DEBUG
1460  unsigned long bitmap_count, x;
1461  struct ext2_super_block *es;
1462 
1463  es = EXT2_SB(sb)->s_es;
1464  desc_count = 0;
1465  bitmap_count = 0;
1466  desc = NULL;
1467  for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1468  struct buffer_head *bitmap_bh;
1469  desc = ext2_get_group_desc (sb, i, NULL);
1470  if (!desc)
1471  continue;
1472  desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1473  bitmap_bh = read_block_bitmap(sb, i);
1474  if (!bitmap_bh)
1475  continue;
1476 
1477  x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1478  printk ("group %d: stored = %d, counted = %lu\n",
1479  i, le16_to_cpu(desc->bg_free_blocks_count), x);
1480  bitmap_count += x;
1481  brelse(bitmap_bh);
1482  }
1483  printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1484  (long)le32_to_cpu(es->s_free_blocks_count),
1485  desc_count, bitmap_count);
1486  return bitmap_count;
1487 #else
1488  for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1489  desc = ext2_get_group_desc (sb, i, NULL);
1490  if (!desc)
1491  continue;
1492  desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1493  }
1494  return desc_count;
1495 #endif
1496 }
1497 
1498 static inline int test_root(int a, int b)
1499 {
1500  int num = b;
1501 
1502  while (a > num)
1503  num *= b;
1504  return num == a;
1505 }
1506 
1507 static int ext2_group_sparse(int group)
1508 {
1509  if (group <= 1)
1510  return 1;
1511  return (test_root(group, 3) || test_root(group, 5) ||
1512  test_root(group, 7));
1513 }
1514 
1523 int ext2_bg_has_super(struct super_block *sb, int group)
1524 {
1526  !ext2_group_sparse(group))
1527  return 0;
1528  return 1;
1529 }
1530 
1540 unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1541 {
1542  return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1543 }
1544