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TOMOYO Linux Cross Reference
Linux/fs/ext3/balloc.c

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  1 /*
  2  *  linux/fs/ext3/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/quotaops.h>
 15 #include <linux/blkdev.h>
 16 #include "ext3.h"
 17 
 18 /*
 19  * balloc.c contains the blocks allocation and deallocation routines
 20  */
 21 
 22 /*
 23  * The free blocks are managed by bitmaps.  A file system contains several
 24  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 25  * block for inodes, N blocks for the inode table and data blocks.
 26  *
 27  * The file system contains group descriptors which are located after the
 28  * super block.  Each descriptor contains the number of the bitmap block and
 29  * the free blocks count in the block.  The descriptors are loaded in memory
 30  * when a file system is mounted (see ext3_fill_super).
 31  */
 32 
 33 
 34 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 35 
 36 /*
 37  * Calculate the block group number and offset, given a block number
 38  */
 39 static void ext3_get_group_no_and_offset(struct super_block *sb,
 40         ext3_fsblk_t blocknr, unsigned long *blockgrpp, ext3_grpblk_t *offsetp)
 41 {
 42         struct ext3_super_block *es = EXT3_SB(sb)->s_es;
 43 
 44         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
 45         if (offsetp)
 46                 *offsetp = blocknr % EXT3_BLOCKS_PER_GROUP(sb);
 47         if (blockgrpp)
 48                 *blockgrpp = blocknr / EXT3_BLOCKS_PER_GROUP(sb);
 49 }
 50 
 51 /**
 52  * ext3_get_group_desc() -- load group descriptor from disk
 53  * @sb:                 super block
 54  * @block_group:        given block group
 55  * @bh:                 pointer to the buffer head to store the block
 56  *                      group descriptor
 57  */
 58 struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
 59                                              unsigned int block_group,
 60                                              struct buffer_head ** bh)
 61 {
 62         unsigned long group_desc;
 63         unsigned long offset;
 64         struct ext3_group_desc * desc;
 65         struct ext3_sb_info *sbi = EXT3_SB(sb);
 66 
 67         if (block_group >= sbi->s_groups_count) {
 68                 ext3_error (sb, "ext3_get_group_desc",
 69                             "block_group >= groups_count - "
 70                             "block_group = %d, groups_count = %lu",
 71                             block_group, sbi->s_groups_count);
 72 
 73                 return NULL;
 74         }
 75         smp_rmb();
 76 
 77         group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
 78         offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
 79         if (!sbi->s_group_desc[group_desc]) {
 80                 ext3_error (sb, "ext3_get_group_desc",
 81                             "Group descriptor not loaded - "
 82                             "block_group = %d, group_desc = %lu, desc = %lu",
 83                              block_group, group_desc, offset);
 84                 return NULL;
 85         }
 86 
 87         desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
 88         if (bh)
 89                 *bh = sbi->s_group_desc[group_desc];
 90         return desc + offset;
 91 }
 92 
 93 static int ext3_valid_block_bitmap(struct super_block *sb,
 94                                         struct ext3_group_desc *desc,
 95                                         unsigned int block_group,
 96                                         struct buffer_head *bh)
 97 {
 98         ext3_grpblk_t offset;
 99         ext3_grpblk_t next_zero_bit;
100         ext3_fsblk_t bitmap_blk;
101         ext3_fsblk_t group_first_block;
102 
103         group_first_block = ext3_group_first_block_no(sb, block_group);
104 
105         /* check whether block bitmap block number is set */
106         bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
107         offset = bitmap_blk - group_first_block;
108         if (!ext3_test_bit(offset, bh->b_data))
109                 /* bad block bitmap */
110                 goto err_out;
111 
112         /* check whether the inode bitmap block number is set */
113         bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
114         offset = bitmap_blk - group_first_block;
115         if (!ext3_test_bit(offset, bh->b_data))
116                 /* bad block bitmap */
117                 goto err_out;
118 
119         /* check whether the inode table block number is set */
120         bitmap_blk = le32_to_cpu(desc->bg_inode_table);
121         offset = bitmap_blk - group_first_block;
122         next_zero_bit = ext3_find_next_zero_bit(bh->b_data,
123                                 offset + EXT3_SB(sb)->s_itb_per_group,
124                                 offset);
125         if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
126                 /* good bitmap for inode tables */
127                 return 1;
128 
129 err_out:
130         ext3_error(sb, __func__,
131                         "Invalid block bitmap - "
132                         "block_group = %d, block = %lu",
133                         block_group, bitmap_blk);
134         return 0;
135 }
136 
137 /**
138  * read_block_bitmap()
139  * @sb:                 super block
140  * @block_group:        given block group
141  *
142  * Read the bitmap for a given block_group,and validate the
143  * bits for block/inode/inode tables are set in the bitmaps
144  *
145  * Return buffer_head on success or NULL in case of failure.
146  */
147 static struct buffer_head *
148 read_block_bitmap(struct super_block *sb, unsigned int block_group)
149 {
150         struct ext3_group_desc * desc;
151         struct buffer_head * bh = NULL;
152         ext3_fsblk_t bitmap_blk;
153 
154         desc = ext3_get_group_desc(sb, block_group, NULL);
155         if (!desc)
156                 return NULL;
157         trace_ext3_read_block_bitmap(sb, block_group);
158         bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
159         bh = sb_getblk(sb, bitmap_blk);
160         if (unlikely(!bh)) {
161                 ext3_error(sb, __func__,
162                             "Cannot read block bitmap - "
163                             "block_group = %d, block_bitmap = %u",
164                             block_group, le32_to_cpu(desc->bg_block_bitmap));
165                 return NULL;
166         }
167         if (likely(bh_uptodate_or_lock(bh)))
168                 return bh;
169 
170         if (bh_submit_read(bh) < 0) {
171                 brelse(bh);
172                 ext3_error(sb, __func__,
173                             "Cannot read block bitmap - "
174                             "block_group = %d, block_bitmap = %u",
175                             block_group, le32_to_cpu(desc->bg_block_bitmap));
176                 return NULL;
177         }
178         ext3_valid_block_bitmap(sb, desc, block_group, bh);
179         /*
180          * file system mounted not to panic on error, continue with corrupt
181          * bitmap
182          */
183         return bh;
184 }
185 /*
186  * The reservation window structure operations
187  * --------------------------------------------
188  * Operations include:
189  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
190  *
191  * We use a red-black tree to represent per-filesystem reservation
192  * windows.
193  *
194  */
195 
196 /**
197  * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
198  * @rb_root:            root of per-filesystem reservation rb tree
199  * @verbose:            verbose mode
200  * @fn:                 function which wishes to dump the reservation map
201  *
202  * If verbose is turned on, it will print the whole block reservation
203  * windows(start, end). Otherwise, it will only print out the "bad" windows,
204  * those windows that overlap with their immediate neighbors.
205  */
206 #if 1
207 static void __rsv_window_dump(struct rb_root *root, int verbose,
208                               const char *fn)
209 {
210         struct rb_node *n;
211         struct ext3_reserve_window_node *rsv, *prev;
212         int bad;
213 
214 restart:
215         n = rb_first(root);
216         bad = 0;
217         prev = NULL;
218 
219         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
220         while (n) {
221                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
222                 if (verbose)
223                         printk("reservation window 0x%p "
224                                "start:  %lu, end:  %lu\n",
225                                rsv, rsv->rsv_start, rsv->rsv_end);
226                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
227                         printk("Bad reservation %p (start >= end)\n",
228                                rsv);
229                         bad = 1;
230                 }
231                 if (prev && prev->rsv_end >= rsv->rsv_start) {
232                         printk("Bad reservation %p (prev->end >= start)\n",
233                                rsv);
234                         bad = 1;
235                 }
236                 if (bad) {
237                         if (!verbose) {
238                                 printk("Restarting reservation walk in verbose mode\n");
239                                 verbose = 1;
240                                 goto restart;
241                         }
242                 }
243                 n = rb_next(n);
244                 prev = rsv;
245         }
246         printk("Window map complete.\n");
247         BUG_ON(bad);
248 }
249 #define rsv_window_dump(root, verbose) \
250         __rsv_window_dump((root), (verbose), __func__)
251 #else
252 #define rsv_window_dump(root, verbose) do {} while (0)
253 #endif
254 
255 /**
256  * goal_in_my_reservation()
257  * @rsv:                inode's reservation window
258  * @grp_goal:           given goal block relative to the allocation block group
259  * @group:              the current allocation block group
260  * @sb:                 filesystem super block
261  *
262  * Test if the given goal block (group relative) is within the file's
263  * own block reservation window range.
264  *
265  * If the reservation window is outside the goal allocation group, return 0;
266  * grp_goal (given goal block) could be -1, which means no specific
267  * goal block. In this case, always return 1.
268  * If the goal block is within the reservation window, return 1;
269  * otherwise, return 0;
270  */
271 static int
272 goal_in_my_reservation(struct ext3_reserve_window *rsv, ext3_grpblk_t grp_goal,
273                         unsigned int group, struct super_block * sb)
274 {
275         ext3_fsblk_t group_first_block, group_last_block;
276 
277         group_first_block = ext3_group_first_block_no(sb, group);
278         group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
279 
280         if ((rsv->_rsv_start > group_last_block) ||
281             (rsv->_rsv_end < group_first_block))
282                 return 0;
283         if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
284                 || (grp_goal + group_first_block > rsv->_rsv_end)))
285                 return 0;
286         return 1;
287 }
288 
289 /**
290  * search_reserve_window()
291  * @rb_root:            root of reservation tree
292  * @goal:               target allocation block
293  *
294  * Find the reserved window which includes the goal, or the previous one
295  * if the goal is not in any window.
296  * Returns NULL if there are no windows or if all windows start after the goal.
297  */
298 static struct ext3_reserve_window_node *
299 search_reserve_window(struct rb_root *root, ext3_fsblk_t goal)
300 {
301         struct rb_node *n = root->rb_node;
302         struct ext3_reserve_window_node *rsv;
303 
304         if (!n)
305                 return NULL;
306 
307         do {
308                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
309 
310                 if (goal < rsv->rsv_start)
311                         n = n->rb_left;
312                 else if (goal > rsv->rsv_end)
313                         n = n->rb_right;
314                 else
315                         return rsv;
316         } while (n);
317         /*
318          * We've fallen off the end of the tree: the goal wasn't inside
319          * any particular node.  OK, the previous node must be to one
320          * side of the interval containing the goal.  If it's the RHS,
321          * we need to back up one.
322          */
323         if (rsv->rsv_start > goal) {
324                 n = rb_prev(&rsv->rsv_node);
325                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
326         }
327         return rsv;
328 }
329 
330 /**
331  * ext3_rsv_window_add() -- Insert a window to the block reservation rb tree.
332  * @sb:                 super block
333  * @rsv:                reservation window to add
334  *
335  * Must be called with rsv_lock hold.
336  */
337 void ext3_rsv_window_add(struct super_block *sb,
338                     struct ext3_reserve_window_node *rsv)
339 {
340         struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
341         struct rb_node *node = &rsv->rsv_node;
342         ext3_fsblk_t start = rsv->rsv_start;
343 
344         struct rb_node ** p = &root->rb_node;
345         struct rb_node * parent = NULL;
346         struct ext3_reserve_window_node *this;
347 
348         trace_ext3_rsv_window_add(sb, rsv);
349         while (*p)
350         {
351                 parent = *p;
352                 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
353 
354                 if (start < this->rsv_start)
355                         p = &(*p)->rb_left;
356                 else if (start > this->rsv_end)
357                         p = &(*p)->rb_right;
358                 else {
359                         rsv_window_dump(root, 1);
360                         BUG();
361                 }
362         }
363 
364         rb_link_node(node, parent, p);
365         rb_insert_color(node, root);
366 }
367 
368 /**
369  * ext3_rsv_window_remove() -- unlink a window from the reservation rb tree
370  * @sb:                 super block
371  * @rsv:                reservation window to remove
372  *
373  * Mark the block reservation window as not allocated, and unlink it
374  * from the filesystem reservation window rb tree. Must be called with
375  * rsv_lock hold.
376  */
377 static void rsv_window_remove(struct super_block *sb,
378                               struct ext3_reserve_window_node *rsv)
379 {
380         rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
381         rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
382         rsv->rsv_alloc_hit = 0;
383         rb_erase(&rsv->rsv_node, &EXT3_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 EXT3_RESERVE_WINDOW_NOT_ALLOCATED.
391  */
392 static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
393 {
394         /* a valid reservation end block could not be 0 */
395         return rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
396 }
397 
398 /**
399  * ext3_init_block_alloc_info()
400  * @inode:              file inode structure
401  *
402  * Allocate and initialize the  reservation window structure, and
403  * link the window to the ext3 inode structure at last
404  *
405  * The reservation window structure is only dynamically allocated
406  * and linked to ext3 inode the first time the open file
407  * needs a new block. So, before every ext3_new_block(s) call, for
408  * regular files, we should check whether the reservation window
409  * structure exists or not. In the latter case, this function is called.
410  * Fail to do so will result in block reservation being turned off for that
411  * open file.
412  *
413  * This function is called from ext3_get_blocks_handle(), also called
414  * when setting the reservation window size through ioctl before the file
415  * is open for write (needs block allocation).
416  *
417  * Needs truncate_mutex protection prior to call this function.
418  */
419 void ext3_init_block_alloc_info(struct inode *inode)
420 {
421         struct ext3_inode_info *ei = EXT3_I(inode);
422         struct ext3_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 ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
428 
429                 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
430                 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
431 
432                 /*
433                  * if filesystem is mounted with NORESERVATION, the goal
434                  * reservation window size is set to zero to indicate
435                  * block reservation is off
436                  */
437                 if (!test_opt(sb, RESERVATION))
438                         rsv->rsv_goal_size = 0;
439                 else
440                         rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
441                 rsv->rsv_alloc_hit = 0;
442                 block_i->last_alloc_logical_block = 0;
443                 block_i->last_alloc_physical_block = 0;
444         }
445         ei->i_block_alloc_info = block_i;
446 }
447 
448 /**
449  * ext3_discard_reservation()
450  * @inode:              inode
451  *
452  * Discard(free) block reservation window on last file close, or truncate
453  * or at last iput().
454  *
455  * It is being called in three cases:
456  *      ext3_release_file(): last writer close the file
457  *      ext3_clear_inode(): last iput(), when nobody link to this file.
458  *      ext3_truncate(): when the block indirect map is about to change.
459  *
460  */
461 void ext3_discard_reservation(struct inode *inode)
462 {
463         struct ext3_inode_info *ei = EXT3_I(inode);
464         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
465         struct ext3_reserve_window_node *rsv;
466         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
467 
468         if (!block_i)
469                 return;
470 
471         rsv = &block_i->rsv_window_node;
472         if (!rsv_is_empty(&rsv->rsv_window)) {
473                 spin_lock(rsv_lock);
474                 if (!rsv_is_empty(&rsv->rsv_window)) {
475                         trace_ext3_discard_reservation(inode, rsv);
476                         rsv_window_remove(inode->i_sb, rsv);
477                 }
478                 spin_unlock(rsv_lock);
479         }
480 }
481 
482 /**
483  * ext3_free_blocks_sb() -- Free given blocks and update quota
484  * @handle:                     handle to this transaction
485  * @sb:                         super block
486  * @block:                      start physical block to free
487  * @count:                      number of blocks to free
488  * @pdquot_freed_blocks:        pointer to quota
489  */
490 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
491                          ext3_fsblk_t block, unsigned long count,
492                          unsigned long *pdquot_freed_blocks)
493 {
494         struct buffer_head *bitmap_bh = NULL;
495         struct buffer_head *gd_bh;
496         unsigned long block_group;
497         ext3_grpblk_t bit;
498         unsigned long i;
499         unsigned long overflow;
500         struct ext3_group_desc * desc;
501         struct ext3_super_block * es;
502         struct ext3_sb_info *sbi;
503         int err = 0, ret;
504         ext3_grpblk_t group_freed;
505 
506         *pdquot_freed_blocks = 0;
507         sbi = EXT3_SB(sb);
508         es = sbi->s_es;
509         if (block < le32_to_cpu(es->s_first_data_block) ||
510             block + count < block ||
511             block + count > le32_to_cpu(es->s_blocks_count)) {
512                 ext3_error (sb, "ext3_free_blocks",
513                             "Freeing blocks not in datazone - "
514                             "block = "E3FSBLK", count = %lu", block, count);
515                 goto error_return;
516         }
517 
518         ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
519 
520 do_more:
521         overflow = 0;
522         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
523                       EXT3_BLOCKS_PER_GROUP(sb);
524         bit = (block - le32_to_cpu(es->s_first_data_block)) %
525                       EXT3_BLOCKS_PER_GROUP(sb);
526         /*
527          * Check to see if we are freeing blocks across a group
528          * boundary.
529          */
530         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
531                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
532                 count -= overflow;
533         }
534         brelse(bitmap_bh);
535         bitmap_bh = read_block_bitmap(sb, block_group);
536         if (!bitmap_bh)
537                 goto error_return;
538         desc = ext3_get_group_desc (sb, block_group, &gd_bh);
539         if (!desc)
540                 goto error_return;
541 
542         if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
543             in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
544             in_range (block, le32_to_cpu(desc->bg_inode_table),
545                       sbi->s_itb_per_group) ||
546             in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
547                       sbi->s_itb_per_group)) {
548                 ext3_error (sb, "ext3_free_blocks",
549                             "Freeing blocks in system zones - "
550                             "Block = "E3FSBLK", count = %lu",
551                             block, count);
552                 goto error_return;
553         }
554 
555         /*
556          * We are about to start releasing blocks in the bitmap,
557          * so we need undo access.
558          */
559         /* @@@ check errors */
560         BUFFER_TRACE(bitmap_bh, "getting undo access");
561         err = ext3_journal_get_undo_access(handle, bitmap_bh);
562         if (err)
563                 goto error_return;
564 
565         /*
566          * We are about to modify some metadata.  Call the journal APIs
567          * to unshare ->b_data if a currently-committing transaction is
568          * using it
569          */
570         BUFFER_TRACE(gd_bh, "get_write_access");
571         err = ext3_journal_get_write_access(handle, gd_bh);
572         if (err)
573                 goto error_return;
574 
575         jbd_lock_bh_state(bitmap_bh);
576 
577         for (i = 0, group_freed = 0; i < count; i++) {
578                 /*
579                  * An HJ special.  This is expensive...
580                  */
581 #ifdef CONFIG_JBD_DEBUG
582                 jbd_unlock_bh_state(bitmap_bh);
583                 {
584                         struct buffer_head *debug_bh;
585                         debug_bh = sb_find_get_block(sb, block + i);
586                         if (debug_bh) {
587                                 BUFFER_TRACE(debug_bh, "Deleted!");
588                                 if (!bh2jh(bitmap_bh)->b_committed_data)
589                                         BUFFER_TRACE(debug_bh,
590                                                 "No committed data in bitmap");
591                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
592                                 __brelse(debug_bh);
593                         }
594                 }
595                 jbd_lock_bh_state(bitmap_bh);
596 #endif
597                 if (need_resched()) {
598                         jbd_unlock_bh_state(bitmap_bh);
599                         cond_resched();
600                         jbd_lock_bh_state(bitmap_bh);
601                 }
602                 /* @@@ This prevents newly-allocated data from being
603                  * freed and then reallocated within the same
604                  * transaction.
605                  *
606                  * Ideally we would want to allow that to happen, but to
607                  * do so requires making journal_forget() capable of
608                  * revoking the queued write of a data block, which
609                  * implies blocking on the journal lock.  *forget()
610                  * cannot block due to truncate races.
611                  *
612                  * Eventually we can fix this by making journal_forget()
613                  * return a status indicating whether or not it was able
614                  * to revoke the buffer.  On successful revoke, it is
615                  * safe not to set the allocation bit in the committed
616                  * bitmap, because we know that there is no outstanding
617                  * activity on the buffer any more and so it is safe to
618                  * reallocate it.
619                  */
620                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
621                 J_ASSERT_BH(bitmap_bh,
622                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
623                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
624                                 bh2jh(bitmap_bh)->b_committed_data);
625 
626                 /*
627                  * We clear the bit in the bitmap after setting the committed
628                  * data bit, because this is the reverse order to that which
629                  * the allocator uses.
630                  */
631                 BUFFER_TRACE(bitmap_bh, "clear bit");
632                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
633                                                 bit + i, bitmap_bh->b_data)) {
634                         jbd_unlock_bh_state(bitmap_bh);
635                         ext3_error(sb, __func__,
636                                 "bit already cleared for block "E3FSBLK,
637                                  block + i);
638                         jbd_lock_bh_state(bitmap_bh);
639                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
640                 } else {
641                         group_freed++;
642                 }
643         }
644         jbd_unlock_bh_state(bitmap_bh);
645 
646         spin_lock(sb_bgl_lock(sbi, block_group));
647         le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
648         spin_unlock(sb_bgl_lock(sbi, block_group));
649         percpu_counter_add(&sbi->s_freeblocks_counter, count);
650 
651         /* We dirtied the bitmap block */
652         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
653         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
654 
655         /* And the group descriptor block */
656         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
657         ret = ext3_journal_dirty_metadata(handle, gd_bh);
658         if (!err) err = ret;
659         *pdquot_freed_blocks += group_freed;
660 
661         if (overflow && !err) {
662                 block += count;
663                 count = overflow;
664                 goto do_more;
665         }
666 
667 error_return:
668         brelse(bitmap_bh);
669         ext3_std_error(sb, err);
670         return;
671 }
672 
673 /**
674  * ext3_free_blocks() -- Free given blocks and update quota
675  * @handle:             handle for this transaction
676  * @inode:              inode
677  * @block:              start physical block to free
678  * @count:              number of blocks to count
679  */
680 void ext3_free_blocks(handle_t *handle, struct inode *inode,
681                         ext3_fsblk_t block, unsigned long count)
682 {
683         struct super_block *sb = inode->i_sb;
684         unsigned long dquot_freed_blocks;
685 
686         trace_ext3_free_blocks(inode, block, count);
687         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
688         if (dquot_freed_blocks)
689                 dquot_free_block(inode, dquot_freed_blocks);
690         return;
691 }
692 
693 /**
694  * ext3_test_allocatable()
695  * @nr:                 given allocation block group
696  * @bh:                 bufferhead contains the bitmap of the given block group
697  *
698  * For ext3 allocations, we must not reuse any blocks which are
699  * allocated in the bitmap buffer's "last committed data" copy.  This
700  * prevents deletes from freeing up the page for reuse until we have
701  * committed the delete transaction.
702  *
703  * If we didn't do this, then deleting something and reallocating it as
704  * data would allow the old block to be overwritten before the
705  * transaction committed (because we force data to disk before commit).
706  * This would lead to corruption if we crashed between overwriting the
707  * data and committing the delete.
708  *
709  * @@@ We may want to make this allocation behaviour conditional on
710  * data-writes at some point, and disable it for metadata allocations or
711  * sync-data inodes.
712  */
713 static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh)
714 {
715         int ret;
716         struct journal_head *jh = bh2jh(bh);
717 
718         if (ext3_test_bit(nr, bh->b_data))
719                 return 0;
720 
721         jbd_lock_bh_state(bh);
722         if (!jh->b_committed_data)
723                 ret = 1;
724         else
725                 ret = !ext3_test_bit(nr, jh->b_committed_data);
726         jbd_unlock_bh_state(bh);
727         return ret;
728 }
729 
730 /**
731  * bitmap_search_next_usable_block()
732  * @start:              the starting block (group relative) of the search
733  * @bh:                 bufferhead contains the block group bitmap
734  * @maxblocks:          the ending block (group relative) of the reservation
735  *
736  * The bitmap search --- search forward alternately through the actual
737  * bitmap on disk and the last-committed copy in journal, until we find a
738  * bit free in both bitmaps.
739  */
740 static ext3_grpblk_t
741 bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
742                                         ext3_grpblk_t maxblocks)
743 {
744         ext3_grpblk_t next;
745         struct journal_head *jh = bh2jh(bh);
746 
747         while (start < maxblocks) {
748                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
749                 if (next >= maxblocks)
750                         return -1;
751                 if (ext3_test_allocatable(next, bh))
752                         return next;
753                 jbd_lock_bh_state(bh);
754                 if (jh->b_committed_data)
755                         start = ext3_find_next_zero_bit(jh->b_committed_data,
756                                                         maxblocks, next);
757                 jbd_unlock_bh_state(bh);
758         }
759         return -1;
760 }
761 
762 /**
763  * find_next_usable_block()
764  * @start:              the starting block (group relative) to find next
765  *                      allocatable block in bitmap.
766  * @bh:                 bufferhead contains the block group bitmap
767  * @maxblocks:          the ending block (group relative) for the search
768  *
769  * Find an allocatable block in a bitmap.  We honor both the bitmap and
770  * its last-committed copy (if that exists), and perform the "most
771  * appropriate allocation" algorithm of looking for a free block near
772  * the initial goal; then for a free byte somewhere in the bitmap; then
773  * for any free bit in the bitmap.
774  */
775 static ext3_grpblk_t
776 find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
777                         ext3_grpblk_t maxblocks)
778 {
779         ext3_grpblk_t here, next;
780         char *p, *r;
781 
782         if (start > 0) {
783                 /*
784                  * The goal was occupied; search forward for a free
785                  * block within the next XX blocks.
786                  *
787                  * end_goal is more or less random, but it has to be
788                  * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
789                  * next 64-bit boundary is simple..
790                  */
791                 ext3_grpblk_t end_goal = (start + 63) & ~63;
792                 if (end_goal > maxblocks)
793                         end_goal = maxblocks;
794                 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
795                 if (here < end_goal && ext3_test_allocatable(here, bh))
796                         return here;
797                 ext3_debug("Bit not found near goal\n");
798         }
799 
800         here = start;
801         if (here < 0)
802                 here = 0;
803 
804         p = bh->b_data + (here >> 3);
805         r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
806         next = (r - bh->b_data) << 3;
807 
808         if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
809                 return next;
810 
811         /*
812          * The bitmap search --- search forward alternately through the actual
813          * bitmap and the last-committed copy until we find a bit free in
814          * both
815          */
816         here = bitmap_search_next_usable_block(here, bh, maxblocks);
817         return here;
818 }
819 
820 /**
821  * claim_block()
822  * @lock:               the spin lock for this block group
823  * @block:              the free block (group relative) to allocate
824  * @bh:                 the buffer_head contains the block group bitmap
825  *
826  * We think we can allocate this block in this bitmap.  Try to set the bit.
827  * If that succeeds then check that nobody has allocated and then freed the
828  * block since we saw that is was not marked in b_committed_data.  If it _was_
829  * allocated and freed then clear the bit in the bitmap again and return
830  * zero (failure).
831  */
832 static inline int
833 claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh)
834 {
835         struct journal_head *jh = bh2jh(bh);
836         int ret;
837 
838         if (ext3_set_bit_atomic(lock, block, bh->b_data))
839                 return 0;
840         jbd_lock_bh_state(bh);
841         if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
842                 ext3_clear_bit_atomic(lock, block, bh->b_data);
843                 ret = 0;
844         } else {
845                 ret = 1;
846         }
847         jbd_unlock_bh_state(bh);
848         return ret;
849 }
850 
851 /**
852  * ext3_try_to_allocate()
853  * @sb:                 superblock
854  * @handle:             handle to this transaction
855  * @group:              given allocation block group
856  * @bitmap_bh:          bufferhead holds the block bitmap
857  * @grp_goal:           given target block within the group
858  * @count:              target number of blocks to allocate
859  * @my_rsv:             reservation window
860  *
861  * Attempt to allocate blocks within a give range. Set the range of allocation
862  * first, then find the first free bit(s) from the bitmap (within the range),
863  * and at last, allocate the blocks by claiming the found free bit as allocated.
864  *
865  * To set the range of this allocation:
866  *      if there is a reservation window, only try to allocate block(s) from the
867  *      file's own reservation window;
868  *      Otherwise, the allocation range starts from the give goal block, ends at
869  *      the block group's last block.
870  *
871  * If we failed to allocate the desired block then we may end up crossing to a
872  * new bitmap.  In that case we must release write access to the old one via
873  * ext3_journal_release_buffer(), else we'll run out of credits.
874  */
875 static ext3_grpblk_t
876 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
877                         struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal,
878                         unsigned long *count, struct ext3_reserve_window *my_rsv)
879 {
880         ext3_fsblk_t group_first_block;
881         ext3_grpblk_t start, end;
882         unsigned long num = 0;
883 
884         /* we do allocation within the reservation window if we have a window */
885         if (my_rsv) {
886                 group_first_block = ext3_group_first_block_no(sb, group);
887                 if (my_rsv->_rsv_start >= group_first_block)
888                         start = my_rsv->_rsv_start - group_first_block;
889                 else
890                         /* reservation window cross group boundary */
891                         start = 0;
892                 end = my_rsv->_rsv_end - group_first_block + 1;
893                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
894                         /* reservation window crosses group boundary */
895                         end = EXT3_BLOCKS_PER_GROUP(sb);
896                 if ((start <= grp_goal) && (grp_goal < end))
897                         start = grp_goal;
898                 else
899                         grp_goal = -1;
900         } else {
901                 if (grp_goal > 0)
902                         start = grp_goal;
903                 else
904                         start = 0;
905                 end = EXT3_BLOCKS_PER_GROUP(sb);
906         }
907 
908         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
909 
910 repeat:
911         if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) {
912                 grp_goal = find_next_usable_block(start, bitmap_bh, end);
913                 if (grp_goal < 0)
914                         goto fail_access;
915                 if (!my_rsv) {
916                         int i;
917 
918                         for (i = 0; i < 7 && grp_goal > start &&
919                                         ext3_test_allocatable(grp_goal - 1,
920                                                                 bitmap_bh);
921                                         i++, grp_goal--)
922                                 ;
923                 }
924         }
925         start = grp_goal;
926 
927         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group),
928                 grp_goal, bitmap_bh)) {
929                 /*
930                  * The block was allocated by another thread, or it was
931                  * allocated and then freed by another thread
932                  */
933                 start++;
934                 grp_goal++;
935                 if (start >= end)
936                         goto fail_access;
937                 goto repeat;
938         }
939         num++;
940         grp_goal++;
941         while (num < *count && grp_goal < end
942                 && ext3_test_allocatable(grp_goal, bitmap_bh)
943                 && claim_block(sb_bgl_lock(EXT3_SB(sb), group),
944                                 grp_goal, bitmap_bh)) {
945                 num++;
946                 grp_goal++;
947         }
948         *count = num;
949         return grp_goal - num;
950 fail_access:
951         *count = num;
952         return -1;
953 }
954 
955 /**
956  *      find_next_reservable_window():
957  *              find a reservable space within the given range.
958  *              It does not allocate the reservation window for now:
959  *              alloc_new_reservation() will do the work later.
960  *
961  *      @search_head: the head of the searching list;
962  *              This is not necessarily the list head of the whole filesystem
963  *
964  *              We have both head and start_block to assist the search
965  *              for the reservable space. The list starts from head,
966  *              but we will shift to the place where start_block is,
967  *              then start from there, when looking for a reservable space.
968  *
969  *      @my_rsv: the reservation window
970  *
971  *      @sb: the super block
972  *
973  *      @start_block: the first block we consider to start
974  *                      the real search from
975  *
976  *      @last_block:
977  *              the maximum block number that our goal reservable space
978  *              could start from. This is normally the last block in this
979  *              group. The search will end when we found the start of next
980  *              possible reservable space is out of this boundary.
981  *              This could handle the cross boundary reservation window
982  *              request.
983  *
984  *      basically we search from the given range, rather than the whole
985  *      reservation double linked list, (start_block, last_block)
986  *      to find a free region that is of my size and has not
987  *      been reserved.
988  *
989  */
990 static int find_next_reservable_window(
991                                 struct ext3_reserve_window_node *search_head,
992                                 struct ext3_reserve_window_node *my_rsv,
993                                 struct super_block * sb,
994                                 ext3_fsblk_t start_block,
995                                 ext3_fsblk_t last_block)
996 {
997         struct rb_node *next;
998         struct ext3_reserve_window_node *rsv, *prev;
999         ext3_fsblk_t cur;
1000         int size = my_rsv->rsv_goal_size;
1001 
1002         /* TODO: make the start of the reservation window byte-aligned */
1003         /* cur = *start_block & ~7;*/
1004         cur = start_block;
1005         rsv = search_head;
1006         if (!rsv)
1007                 return -1;
1008 
1009         while (1) {
1010                 if (cur <= rsv->rsv_end)
1011                         cur = rsv->rsv_end + 1;
1012 
1013                 /* TODO?
1014                  * in the case we could not find a reservable space
1015                  * that is what is expected, during the re-search, we could
1016                  * remember what's the largest reservable space we could have
1017                  * and return that one.
1018                  *
1019                  * For now it will fail if we could not find the reservable
1020                  * space with expected-size (or more)...
1021                  */
1022                 if (cur > last_block)
1023                         return -1;              /* fail */
1024 
1025                 prev = rsv;
1026                 next = rb_next(&rsv->rsv_node);
1027                 rsv = rb_entry(next,struct ext3_reserve_window_node,rsv_node);
1028 
1029                 /*
1030                  * Reached the last reservation, we can just append to the
1031                  * previous one.
1032                  */
1033                 if (!next)
1034                         break;
1035 
1036                 if (cur + size <= rsv->rsv_start) {
1037                         /*
1038                          * Found a reserveable space big enough.  We could
1039                          * have a reservation across the group boundary here
1040                          */
1041                         break;
1042                 }
1043         }
1044         /*
1045          * we come here either :
1046          * when we reach the end of the whole list,
1047          * and there is empty reservable space after last entry in the list.
1048          * append it to the end of the list.
1049          *
1050          * or we found one reservable space in the middle of the list,
1051          * return the reservation window that we could append to.
1052          * succeed.
1053          */
1054 
1055         if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
1056                 rsv_window_remove(sb, my_rsv);
1057 
1058         /*
1059          * Let's book the whole available window for now.  We will check the
1060          * disk bitmap later and then, if there are free blocks then we adjust
1061          * the window size if it's larger than requested.
1062          * Otherwise, we will remove this node from the tree next time
1063          * call find_next_reservable_window.
1064          */
1065         my_rsv->rsv_start = cur;
1066         my_rsv->rsv_end = cur + size - 1;
1067         my_rsv->rsv_alloc_hit = 0;
1068 
1069         if (prev != my_rsv)
1070                 ext3_rsv_window_add(sb, my_rsv);
1071 
1072         return 0;
1073 }
1074 
1075 /**
1076  *      alloc_new_reservation()--allocate a new reservation window
1077  *
1078  *              To make a new reservation, we search part of the filesystem
1079  *              reservation list (the list that inside the group). We try to
1080  *              allocate a new reservation window near the allocation goal,
1081  *              or the beginning of the group, if there is no goal.
1082  *
1083  *              We first find a reservable space after the goal, then from
1084  *              there, we check the bitmap for the first free block after
1085  *              it. If there is no free block until the end of group, then the
1086  *              whole group is full, we failed. Otherwise, check if the free
1087  *              block is inside the expected reservable space, if so, we
1088  *              succeed.
1089  *              If the first free block is outside the reservable space, then
1090  *              start from the first free block, we search for next available
1091  *              space, and go on.
1092  *
1093  *      on succeed, a new reservation will be found and inserted into the list
1094  *      It contains at least one free block, and it does not overlap with other
1095  *      reservation windows.
1096  *
1097  *      failed: we failed to find a reservation window in this group
1098  *
1099  *      @my_rsv: the reservation window
1100  *
1101  *      @grp_goal: The goal (group-relative).  It is where the search for a
1102  *              free reservable space should start from.
1103  *              if we have a grp_goal(grp_goal >0 ), then start from there,
1104  *              no grp_goal(grp_goal = -1), we start from the first block
1105  *              of the group.
1106  *
1107  *      @sb: the super block
1108  *      @group: the group we are trying to allocate in
1109  *      @bitmap_bh: the block group block bitmap
1110  *
1111  */
1112 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
1113                 ext3_grpblk_t grp_goal, struct super_block *sb,
1114                 unsigned int group, struct buffer_head *bitmap_bh)
1115 {
1116         struct ext3_reserve_window_node *search_head;
1117         ext3_fsblk_t group_first_block, group_end_block, start_block;
1118         ext3_grpblk_t first_free_block;
1119         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
1120         unsigned long size;
1121         int ret;
1122         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1123 
1124         group_first_block = ext3_group_first_block_no(sb, group);
1125         group_end_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1126 
1127         if (grp_goal < 0)
1128                 start_block = group_first_block;
1129         else
1130                 start_block = grp_goal + group_first_block;
1131 
1132         trace_ext3_alloc_new_reservation(sb, start_block);
1133         size = my_rsv->rsv_goal_size;
1134 
1135         if (!rsv_is_empty(&my_rsv->rsv_window)) {
1136                 /*
1137                  * if the old reservation is cross group boundary
1138                  * and if the goal is inside the old reservation window,
1139                  * we will come here when we just failed to allocate from
1140                  * the first part of the window. We still have another part
1141                  * that belongs to the next group. In this case, there is no
1142                  * point to discard our window and try to allocate a new one
1143                  * in this group(which will fail). we should
1144                  * keep the reservation window, just simply move on.
1145                  *
1146                  * Maybe we could shift the start block of the reservation
1147                  * window to the first block of next group.
1148                  */
1149 
1150                 if ((my_rsv->rsv_start <= group_end_block) &&
1151                                 (my_rsv->rsv_end > group_end_block) &&
1152                                 (start_block >= my_rsv->rsv_start))
1153                         return -1;
1154 
1155                 if ((my_rsv->rsv_alloc_hit >
1156                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
1157                         /*
1158                          * if the previously allocation hit ratio is
1159                          * greater than 1/2, then we double the size of
1160                          * the reservation window the next time,
1161                          * otherwise we keep the same size window
1162                          */
1163                         size = size * 2;
1164                         if (size > EXT3_MAX_RESERVE_BLOCKS)
1165                                 size = EXT3_MAX_RESERVE_BLOCKS;
1166                         my_rsv->rsv_goal_size= size;
1167                 }
1168         }
1169 
1170         spin_lock(rsv_lock);
1171         /*
1172          * shift the search start to the window near the goal block
1173          */
1174         search_head = search_reserve_window(fs_rsv_root, start_block);
1175 
1176         /*
1177          * find_next_reservable_window() simply finds a reservable window
1178          * inside the given range(start_block, group_end_block).
1179          *
1180          * To make sure the reservation window has a free bit inside it, we
1181          * need to check the bitmap after we found a reservable window.
1182          */
1183 retry:
1184         ret = find_next_reservable_window(search_head, my_rsv, sb,
1185                                                 start_block, group_end_block);
1186 
1187         if (ret == -1) {
1188                 if (!rsv_is_empty(&my_rsv->rsv_window))
1189                         rsv_window_remove(sb, my_rsv);
1190                 spin_unlock(rsv_lock);
1191                 return -1;
1192         }
1193 
1194         /*
1195          * On success, find_next_reservable_window() returns the
1196          * reservation window where there is a reservable space after it.
1197          * Before we reserve this reservable space, we need
1198          * to make sure there is at least a free block inside this region.
1199          *
1200          * searching the first free bit on the block bitmap and copy of
1201          * last committed bitmap alternatively, until we found a allocatable
1202          * block. Search start from the start block of the reservable space
1203          * we just found.
1204          */
1205         spin_unlock(rsv_lock);
1206         first_free_block = bitmap_search_next_usable_block(
1207                         my_rsv->rsv_start - group_first_block,
1208                         bitmap_bh, group_end_block - group_first_block + 1);
1209 
1210         if (first_free_block < 0) {
1211                 /*
1212                  * no free block left on the bitmap, no point
1213                  * to reserve the space. return failed.
1214                  */
1215                 spin_lock(rsv_lock);
1216                 if (!rsv_is_empty(&my_rsv->rsv_window))
1217                         rsv_window_remove(sb, my_rsv);
1218                 spin_unlock(rsv_lock);
1219                 return -1;              /* failed */
1220         }
1221 
1222         start_block = first_free_block + group_first_block;
1223         /*
1224          * check if the first free block is within the
1225          * free space we just reserved
1226          */
1227         if (start_block >= my_rsv->rsv_start &&
1228             start_block <= my_rsv->rsv_end) {
1229                 trace_ext3_reserved(sb, start_block, my_rsv);
1230                 return 0;               /* success */
1231         }
1232         /*
1233          * if the first free bit we found is out of the reservable space
1234          * continue search for next reservable space,
1235          * start from where the free block is,
1236          * we also shift the list head to where we stopped last time
1237          */
1238         search_head = my_rsv;
1239         spin_lock(rsv_lock);
1240         goto retry;
1241 }
1242 
1243 /**
1244  * try_to_extend_reservation()
1245  * @my_rsv:             given reservation window
1246  * @sb:                 super block
1247  * @size:               the delta to extend
1248  *
1249  * Attempt to expand the reservation window large enough to have
1250  * required number of free blocks
1251  *
1252  * Since ext3_try_to_allocate() will always allocate blocks within
1253  * the reservation window range, if the window size is too small,
1254  * multiple blocks allocation has to stop at the end of the reservation
1255  * window. To make this more efficient, given the total number of
1256  * blocks needed and the current size of the window, we try to
1257  * expand the reservation window size if necessary on a best-effort
1258  * basis before ext3_new_blocks() tries to allocate blocks,
1259  */
1260 static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
1261                         struct super_block *sb, int size)
1262 {
1263         struct ext3_reserve_window_node *next_rsv;
1264         struct rb_node *next;
1265         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1266 
1267         if (!spin_trylock(rsv_lock))
1268                 return;
1269 
1270         next = rb_next(&my_rsv->rsv_node);
1271 
1272         if (!next)
1273                 my_rsv->rsv_end += size;
1274         else {
1275                 next_rsv = rb_entry(next, struct ext3_reserve_window_node, rsv_node);
1276 
1277                 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1278                         my_rsv->rsv_end += size;
1279                 else
1280                         my_rsv->rsv_end = next_rsv->rsv_start - 1;
1281         }
1282         spin_unlock(rsv_lock);
1283 }
1284 
1285 /**
1286  * ext3_try_to_allocate_with_rsv()
1287  * @sb:                 superblock
1288  * @handle:             handle to this transaction
1289  * @group:              given allocation block group
1290  * @bitmap_bh:          bufferhead holds the block bitmap
1291  * @grp_goal:           given target block within the group
1292  * @my_rsv:             reservation window
1293  * @count:              target number of blocks to allocate
1294  * @errp:               pointer to store the error code
1295  *
1296  * This is the main function used to allocate a new block and its reservation
1297  * window.
1298  *
1299  * Each time when a new block allocation is need, first try to allocate from
1300  * its own reservation.  If it does not have a reservation window, instead of
1301  * looking for a free bit on bitmap first, then look up the reservation list to
1302  * see if it is inside somebody else's reservation window, we try to allocate a
1303  * reservation window for it starting from the goal first. Then do the block
1304  * allocation within the reservation window.
1305  *
1306  * This will avoid keeping on searching the reservation list again and
1307  * again when somebody is looking for a free block (without
1308  * reservation), and there are lots of free blocks, but they are all
1309  * being reserved.
1310  *
1311  * We use a red-black tree for the per-filesystem reservation list.
1312  *
1313  */
1314 static ext3_grpblk_t
1315 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1316                         unsigned int group, struct buffer_head *bitmap_bh,
1317                         ext3_grpblk_t grp_goal,
1318                         struct ext3_reserve_window_node * my_rsv,
1319                         unsigned long *count, int *errp)
1320 {
1321         ext3_fsblk_t group_first_block, group_last_block;
1322         ext3_grpblk_t ret = 0;
1323         int fatal;
1324         unsigned long num = *count;
1325 
1326         *errp = 0;
1327 
1328         /*
1329          * Make sure we use undo access for the bitmap, because it is critical
1330          * that we do the frozen_data COW on bitmap buffers in all cases even
1331          * if the buffer is in BJ_Forget state in the committing transaction.
1332          */
1333         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1334         fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1335         if (fatal) {
1336                 *errp = fatal;
1337                 return -1;
1338         }
1339 
1340         /*
1341          * we don't deal with reservation when
1342          * filesystem is mounted without reservation
1343          * or the file is not a regular file
1344          * or last attempt to allocate a block with reservation turned on failed
1345          */
1346         if (my_rsv == NULL ) {
1347                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1348                                                 grp_goal, count, NULL);
1349                 goto out;
1350         }
1351         /*
1352          * grp_goal is a group relative block number (if there is a goal)
1353          * 0 <= grp_goal < EXT3_BLOCKS_PER_GROUP(sb)
1354          * first block is a filesystem wide block number
1355          * first block is the block number of the first block in this group
1356          */
1357         group_first_block = ext3_group_first_block_no(sb, group);
1358         group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1359 
1360         /*
1361          * Basically we will allocate a new block from inode's reservation
1362          * window.
1363          *
1364          * We need to allocate a new reservation window, if:
1365          * a) inode does not have a reservation window; or
1366          * b) last attempt to allocate a block from existing reservation
1367          *    failed; or
1368          * c) we come here with a goal and with a reservation window
1369          *
1370          * We do not need to allocate a new reservation window if we come here
1371          * at the beginning with a goal and the goal is inside the window, or
1372          * we don't have a goal but already have a reservation window.
1373          * then we could go to allocate from the reservation window directly.
1374          */
1375         while (1) {
1376                 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1377                         !goal_in_my_reservation(&my_rsv->rsv_window,
1378                                                 grp_goal, group, sb)) {
1379                         if (my_rsv->rsv_goal_size < *count)
1380                                 my_rsv->rsv_goal_size = *count;
1381                         ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1382                                                         group, bitmap_bh);
1383                         if (ret < 0)
1384                                 break;                  /* failed */
1385 
1386                         if (!goal_in_my_reservation(&my_rsv->rsv_window,
1387                                                         grp_goal, group, sb))
1388                                 grp_goal = -1;
1389                 } else if (grp_goal >= 0) {
1390                         int curr = my_rsv->rsv_end -
1391                                         (grp_goal + group_first_block) + 1;
1392 
1393                         if (curr < *count)
1394                                 try_to_extend_reservation(my_rsv, sb,
1395                                                         *count - curr);
1396                 }
1397 
1398                 if ((my_rsv->rsv_start > group_last_block) ||
1399                                 (my_rsv->rsv_end < group_first_block)) {
1400                         rsv_window_dump(&EXT3_SB(sb)->s_rsv_window_root, 1);
1401                         BUG();
1402                 }
1403                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1404                                            grp_goal, &num, &my_rsv->rsv_window);
1405                 if (ret >= 0) {
1406                         my_rsv->rsv_alloc_hit += num;
1407                         *count = num;
1408                         break;                          /* succeed */
1409                 }
1410                 num = *count;
1411         }
1412 out:
1413         if (ret >= 0) {
1414                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1415                                         "bitmap block");
1416                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1417                 if (fatal) {
1418                         *errp = fatal;
1419                         return -1;
1420                 }
1421                 return ret;
1422         }
1423 
1424         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1425         ext3_journal_release_buffer(handle, bitmap_bh);
1426         return ret;
1427 }
1428 
1429 /**
1430  * ext3_has_free_blocks()
1431  * @sbi:                in-core super block structure.
1432  *
1433  * Check if filesystem has at least 1 free block available for allocation.
1434  */
1435 static int ext3_has_free_blocks(struct ext3_sb_info *sbi, int use_reservation)
1436 {
1437         ext3_fsblk_t free_blocks, root_blocks;
1438 
1439         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1440         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1441         if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1442                 !use_reservation && !uid_eq(sbi->s_resuid, current_fsuid()) &&
1443                 (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
1444                  !in_group_p (sbi->s_resgid))) {
1445                 return 0;
1446         }
1447         return 1;
1448 }
1449 
1450 /**
1451  * ext3_should_retry_alloc()
1452  * @sb:                 super block
1453  * @retries             number of attemps has been made
1454  *
1455  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1456  * it is profitable to retry the operation, this function will wait
1457  * for the current or committing transaction to complete, and then
1458  * return TRUE.
1459  *
1460  * if the total number of retries exceed three times, return FALSE.
1461  */
1462 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1463 {
1464         if (!ext3_has_free_blocks(EXT3_SB(sb), 0) || (*retries)++ > 3)
1465                 return 0;
1466 
1467         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1468 
1469         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1470 }
1471 
1472 /**
1473  * ext3_new_blocks() -- core block(s) allocation function
1474  * @handle:             handle to this transaction
1475  * @inode:              file inode
1476  * @goal:               given target block(filesystem wide)
1477  * @count:              target number of blocks to allocate
1478  * @errp:               error code
1479  *
1480  * ext3_new_blocks uses a goal block to assist allocation.  It tries to
1481  * allocate block(s) from the block group contains the goal block first. If that
1482  * fails, it will try to allocate block(s) from other block groups without
1483  * any specific goal block.
1484  *
1485  */
1486 ext3_fsblk_t ext3_new_blocks(handle_t *handle, struct inode *inode,
1487                         ext3_fsblk_t goal, unsigned long *count, int *errp)
1488 {
1489         struct buffer_head *bitmap_bh = NULL;
1490         struct buffer_head *gdp_bh;
1491         int group_no;
1492         int goal_group;
1493         ext3_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1494         ext3_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1495         ext3_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1496         int bgi;                        /* blockgroup iteration index */
1497         int fatal = 0, err;
1498         int performed_allocation = 0;
1499         ext3_grpblk_t free_blocks;      /* number of free blocks in a group */
1500         struct super_block *sb;
1501         struct ext3_group_desc *gdp;
1502         struct ext3_super_block *es;
1503         struct ext3_sb_info *sbi;
1504         struct ext3_reserve_window_node *my_rsv = NULL;
1505         struct ext3_block_alloc_info *block_i;
1506         unsigned short windowsz = 0;
1507 #ifdef EXT3FS_DEBUG
1508         static int goal_hits, goal_attempts;
1509 #endif
1510         unsigned long ngroups;
1511         unsigned long num = *count;
1512 
1513         *errp = -ENOSPC;
1514         sb = inode->i_sb;
1515 
1516         /*
1517          * Check quota for allocation of this block.
1518          */
1519         err = dquot_alloc_block(inode, num);
1520         if (err) {
1521                 *errp = err;
1522                 return 0;
1523         }
1524 
1525         trace_ext3_request_blocks(inode, goal, num);
1526 
1527         sbi = EXT3_SB(sb);
1528         es = sbi->s_es;
1529         ext3_debug("goal=%lu.\n", goal);
1530         /*
1531          * Allocate a block from reservation only when
1532          * filesystem is mounted with reservation(default,-o reservation), and
1533          * it's a regular file, and
1534          * the desired window size is greater than 0 (One could use ioctl
1535          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1536          * reservation on that particular file)
1537          */
1538         block_i = EXT3_I(inode)->i_block_alloc_info;
1539         if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1540                 my_rsv = &block_i->rsv_window_node;
1541 
1542         if (!ext3_has_free_blocks(sbi, IS_NOQUOTA(inode))) {
1543                 *errp = -ENOSPC;
1544                 goto out;
1545         }
1546 
1547         /*
1548          * First, test whether the goal block is free.
1549          */
1550         if (goal < le32_to_cpu(es->s_first_data_block) ||
1551             goal >= le32_to_cpu(es->s_blocks_count))
1552                 goal = le32_to_cpu(es->s_first_data_block);
1553         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1554                         EXT3_BLOCKS_PER_GROUP(sb);
1555         goal_group = group_no;
1556 retry_alloc:
1557         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1558         if (!gdp)
1559                 goto io_error;
1560 
1561         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1562         /*
1563          * if there is not enough free blocks to make a new resevation
1564          * turn off reservation for this allocation
1565          */
1566         if (my_rsv && (free_blocks < windowsz)
1567                 && (free_blocks > 0)
1568                 && (rsv_is_empty(&my_rsv->rsv_window)))
1569                 my_rsv = NULL;
1570 
1571         if (free_blocks > 0) {
1572                 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1573                                 EXT3_BLOCKS_PER_GROUP(sb));
1574                 bitmap_bh = read_block_bitmap(sb, group_no);
1575                 if (!bitmap_bh)
1576                         goto io_error;
1577                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1578                                         group_no, bitmap_bh, grp_target_blk,
1579                                         my_rsv, &num, &fatal);
1580                 if (fatal)
1581                         goto out;
1582                 if (grp_alloc_blk >= 0)
1583                         goto allocated;
1584         }
1585 
1586         ngroups = EXT3_SB(sb)->s_groups_count;
1587         smp_rmb();
1588 
1589         /*
1590          * Now search the rest of the groups.  We assume that
1591          * group_no and gdp correctly point to the last group visited.
1592          */
1593         for (bgi = 0; bgi < ngroups; bgi++) {
1594                 group_no++;
1595                 if (group_no >= ngroups)
1596                         group_no = 0;
1597                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1598                 if (!gdp)
1599                         goto io_error;
1600                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1601                 /*
1602                  * skip this group (and avoid loading bitmap) if there
1603                  * are no free blocks
1604                  */
1605                 if (!free_blocks)
1606                         continue;
1607                 /*
1608                  * skip this group if the number of
1609                  * free blocks is less than half of the reservation
1610                  * window size.
1611                  */
1612                 if (my_rsv && (free_blocks <= (windowsz/2)))
1613                         continue;
1614 
1615                 brelse(bitmap_bh);
1616                 bitmap_bh = read_block_bitmap(sb, group_no);
1617                 if (!bitmap_bh)
1618                         goto io_error;
1619                 /*
1620                  * try to allocate block(s) from this group, without a goal(-1).
1621                  */
1622                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1623                                         group_no, bitmap_bh, -1, my_rsv,
1624                                         &num, &fatal);
1625                 if (fatal)
1626                         goto out;
1627                 if (grp_alloc_blk >= 0)
1628                         goto allocated;
1629         }
1630         /*
1631          * We may end up a bogus earlier ENOSPC error due to
1632          * filesystem is "full" of reservations, but
1633          * there maybe indeed free blocks available on disk
1634          * In this case, we just forget about the reservations
1635          * just do block allocation as without reservations.
1636          */
1637         if (my_rsv) {
1638                 my_rsv = NULL;
1639                 windowsz = 0;
1640                 group_no = goal_group;
1641                 goto retry_alloc;
1642         }
1643         /* No space left on the device */
1644         *errp = -ENOSPC;
1645         goto out;
1646 
1647 allocated:
1648 
1649         ext3_debug("using block group %d(%d)\n",
1650                         group_no, gdp->bg_free_blocks_count);
1651 
1652         BUFFER_TRACE(gdp_bh, "get_write_access");
1653         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1654         if (fatal)
1655                 goto out;
1656 
1657         ret_block = grp_alloc_blk + ext3_group_first_block_no(sb, group_no);
1658 
1659         if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1660             in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1661             in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1662                       EXT3_SB(sb)->s_itb_per_group) ||
1663             in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1664                       EXT3_SB(sb)->s_itb_per_group)) {
1665                 ext3_error(sb, "ext3_new_block",
1666                             "Allocating block in system zone - "
1667                             "blocks from "E3FSBLK", length %lu",
1668                              ret_block, num);
1669                 /*
1670                  * claim_block() marked the blocks we allocated as in use. So we
1671                  * may want to selectively mark some of the blocks as free.
1672                  */
1673                 goto retry_alloc;
1674         }
1675 
1676         performed_allocation = 1;
1677 
1678 #ifdef CONFIG_JBD_DEBUG
1679         {
1680                 struct buffer_head *debug_bh;
1681 
1682                 /* Record bitmap buffer state in the newly allocated block */
1683                 debug_bh = sb_find_get_block(sb, ret_block);
1684                 if (debug_bh) {
1685                         BUFFER_TRACE(debug_bh, "state when allocated");
1686                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1687                         brelse(debug_bh);
1688                 }
1689         }
1690         jbd_lock_bh_state(bitmap_bh);
1691         spin_lock(sb_bgl_lock(sbi, group_no));
1692         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1693                 int i;
1694 
1695                 for (i = 0; i < num; i++) {
1696                         if (ext3_test_bit(grp_alloc_blk+i,
1697                                         bh2jh(bitmap_bh)->b_committed_data)) {
1698                                 printk("%s: block was unexpectedly set in "
1699                                         "b_committed_data\n", __func__);
1700                         }
1701                 }
1702         }
1703         ext3_debug("found bit %d\n", grp_alloc_blk);
1704         spin_unlock(sb_bgl_lock(sbi, group_no));
1705         jbd_unlock_bh_state(bitmap_bh);
1706 #endif
1707 
1708         if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1709                 ext3_error(sb, "ext3_new_block",
1710                             "block("E3FSBLK") >= blocks count(%d) - "
1711                             "block_group = %d, es == %p ", ret_block,
1712                         le32_to_cpu(es->s_blocks_count), group_no, es);
1713                 goto out;
1714         }
1715 
1716         /*
1717          * It is up to the caller to add the new buffer to a journal
1718          * list of some description.  We don't know in advance whether
1719          * the caller wants to use it as metadata or data.
1720          */
1721         ext3_debug("allocating block %lu. Goal hits %d of %d.\n",
1722                         ret_block, goal_hits, goal_attempts);
1723 
1724         spin_lock(sb_bgl_lock(sbi, group_no));
1725         le16_add_cpu(&gdp->bg_free_blocks_count, -num);
1726         spin_unlock(sb_bgl_lock(sbi, group_no));
1727         percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1728 
1729         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1730         fatal = ext3_journal_dirty_metadata(handle, gdp_bh);
1731         if (fatal)
1732                 goto out;
1733 
1734         *errp = 0;
1735         brelse(bitmap_bh);
1736 
1737         if (num < *count) {
1738                 dquot_free_block(inode, *count-num);
1739                 *count = num;
1740         }
1741 
1742         trace_ext3_allocate_blocks(inode, goal, num,
1743                                    (unsigned long long)ret_block);
1744 
1745         return ret_block;
1746 
1747 io_error:
1748         *errp = -EIO;
1749 out:
1750         if (fatal) {
1751                 *errp = fatal;
1752                 ext3_std_error(sb, fatal);
1753         }
1754         /*
1755          * Undo the block allocation
1756          */
1757         if (!performed_allocation)
1758                 dquot_free_block(inode, *count);
1759         brelse(bitmap_bh);
1760         return 0;
1761 }
1762 
1763 ext3_fsblk_t ext3_new_block(handle_t *handle, struct inode *inode,
1764                         ext3_fsblk_t goal, int *errp)
1765 {
1766         unsigned long count = 1;
1767 
1768         return ext3_new_blocks(handle, inode, goal, &count, errp);
1769 }
1770 
1771 /**
1772  * ext3_count_free_blocks() -- count filesystem free blocks
1773  * @sb:         superblock
1774  *
1775  * Adds up the number of free blocks from each block group.
1776  */
1777 ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
1778 {
1779         ext3_fsblk_t desc_count;
1780         struct ext3_group_desc *gdp;
1781         int i;
1782         unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1783 #ifdef EXT3FS_DEBUG
1784         struct ext3_super_block *es;
1785         ext3_fsblk_t bitmap_count;
1786         unsigned long x;
1787         struct buffer_head *bitmap_bh = NULL;
1788 
1789         es = EXT3_SB(sb)->s_es;
1790         desc_count = 0;
1791         bitmap_count = 0;
1792         gdp = NULL;
1793 
1794         smp_rmb();
1795         for (i = 0; i < ngroups; i++) {
1796                 gdp = ext3_get_group_desc(sb, i, NULL);
1797                 if (!gdp)
1798                         continue;
1799                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1800                 brelse(bitmap_bh);
1801                 bitmap_bh = read_block_bitmap(sb, i);
1802                 if (bitmap_bh == NULL)
1803                         continue;
1804 
1805                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1806                 printk("group %d: stored = %d, counted = %lu\n",
1807                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1808                 bitmap_count += x;
1809         }
1810         brelse(bitmap_bh);
1811         printk("ext3_count_free_blocks: stored = "E3FSBLK
1812                 ", computed = "E3FSBLK", "E3FSBLK"\n",
1813                (ext3_fsblk_t)le32_to_cpu(es->s_free_blocks_count),
1814                 desc_count, bitmap_count);
1815         return bitmap_count;
1816 #else
1817         desc_count = 0;
1818         smp_rmb();
1819         for (i = 0; i < ngroups; i++) {
1820                 gdp = ext3_get_group_desc(sb, i, NULL);
1821                 if (!gdp)
1822                         continue;
1823                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1824         }
1825 
1826         return desc_count;
1827 #endif
1828 }
1829 
1830 static inline int test_root(int a, int b)
1831 {
1832         int num = b;
1833 
1834         while (a > num)
1835                 num *= b;
1836         return num == a;
1837 }
1838 
1839 static int ext3_group_sparse(int group)
1840 {
1841         if (group <= 1)
1842                 return 1;
1843         if (!(group & 1))
1844                 return 0;
1845         return (test_root(group, 7) || test_root(group, 5) ||
1846                 test_root(group, 3));
1847 }
1848 
1849 /**
1850  *      ext3_bg_has_super - number of blocks used by the superblock in group
1851  *      @sb: superblock for filesystem
1852  *      @group: group number to check
1853  *
1854  *      Return the number of blocks used by the superblock (primary or backup)
1855  *      in this group.  Currently this will be only 0 or 1.
1856  */
1857 int ext3_bg_has_super(struct super_block *sb, int group)
1858 {
1859         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1860                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1861                         !ext3_group_sparse(group))
1862                 return 0;
1863         return 1;
1864 }
1865 
1866 static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
1867 {
1868         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1869         unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
1870         unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
1871 
1872         if (group == first || group == first + 1 || group == last)
1873                 return 1;
1874         return 0;
1875 }
1876 
1877 static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
1878 {
1879         return ext3_bg_has_super(sb, group) ? EXT3_SB(sb)->s_gdb_count : 0;
1880 }
1881 
1882 /**
1883  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1884  *      @sb: superblock for filesystem
1885  *      @group: group number to check
1886  *
1887  *      Return the number of blocks used by the group descriptor table
1888  *      (primary or backup) in this group.  In the future there may be a
1889  *      different number of descriptor blocks in each group.
1890  */
1891 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1892 {
1893         unsigned long first_meta_bg =
1894                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
1895         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1896 
1897         if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
1898                         metagroup < first_meta_bg)
1899                 return ext3_bg_num_gdb_nometa(sb,group);
1900 
1901         return ext3_bg_num_gdb_meta(sb,group);
1902 
1903 }
1904 
1905 /**
1906  * ext3_trim_all_free -- function to trim all free space in alloc. group
1907  * @sb:                 super block for file system
1908  * @group:              allocation group to trim
1909  * @start:              first group block to examine
1910  * @max:                last group block to examine
1911  * @gdp:                allocation group description structure
1912  * @minblocks:          minimum extent block count
1913  *
1914  * ext3_trim_all_free walks through group's block bitmap searching for free
1915  * blocks. When the free block is found, it tries to allocate this block and
1916  * consequent free block to get the biggest free extent possible, until it
1917  * reaches any used block. Then issue a TRIM command on this extent and free
1918  * the extent in the block bitmap. This is done until whole group is scanned.
1919  */
1920 static ext3_grpblk_t ext3_trim_all_free(struct super_block *sb,
1921                                         unsigned int group,
1922                                         ext3_grpblk_t start, ext3_grpblk_t max,
1923                                         ext3_grpblk_t minblocks)
1924 {
1925         handle_t *handle;
1926         ext3_grpblk_t next, free_blocks, bit, freed, count = 0;
1927         ext3_fsblk_t discard_block;
1928         struct ext3_sb_info *sbi;
1929         struct buffer_head *gdp_bh, *bitmap_bh = NULL;
1930         struct ext3_group_desc *gdp;
1931         int err = 0, ret = 0;
1932 
1933         /*
1934          * We will update one block bitmap, and one group descriptor
1935          */
1936         handle = ext3_journal_start_sb(sb, 2);
1937         if (IS_ERR(handle))
1938                 return PTR_ERR(handle);
1939 
1940         bitmap_bh = read_block_bitmap(sb, group);
1941         if (!bitmap_bh) {
1942                 err = -EIO;
1943                 goto err_out;
1944         }
1945 
1946         BUFFER_TRACE(bitmap_bh, "getting undo access");
1947         err = ext3_journal_get_undo_access(handle, bitmap_bh);
1948         if (err)
1949                 goto err_out;
1950 
1951         gdp = ext3_get_group_desc(sb, group, &gdp_bh);
1952         if (!gdp) {
1953                 err = -EIO;
1954                 goto err_out;
1955         }
1956 
1957         BUFFER_TRACE(gdp_bh, "get_write_access");
1958         err = ext3_journal_get_write_access(handle, gdp_bh);
1959         if (err)
1960                 goto err_out;
1961 
1962         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1963         sbi = EXT3_SB(sb);
1964 
1965          /* Walk through the whole group */
1966         while (start <= max) {
1967                 start = bitmap_search_next_usable_block(start, bitmap_bh, max);
1968                 if (start < 0)
1969                         break;
1970                 next = start;
1971 
1972                 /*
1973                  * Allocate contiguous free extents by setting bits in the
1974                  * block bitmap
1975                  */
1976                 while (next <= max
1977                         && claim_block(sb_bgl_lock(sbi, group),
1978                                         next, bitmap_bh)) {
1979                         next++;
1980                 }
1981 
1982                  /* We did not claim any blocks */
1983                 if (next == start)
1984                         continue;
1985 
1986                 discard_block = (ext3_fsblk_t)start +
1987                                 ext3_group_first_block_no(sb, group);
1988 
1989                 /* Update counters */
1990                 spin_lock(sb_bgl_lock(sbi, group));
1991                 le16_add_cpu(&gdp->bg_free_blocks_count, start - next);
1992                 spin_unlock(sb_bgl_lock(sbi, group));
1993                 percpu_counter_sub(&sbi->s_freeblocks_counter, next - start);
1994 
1995                 free_blocks -= next - start;
1996                 /* Do not issue a TRIM on extents smaller than minblocks */
1997                 if ((next - start) < minblocks)
1998                         goto free_extent;
1999 
2000                 trace_ext3_discard_blocks(sb, discard_block, next - start);
2001                  /* Send the TRIM command down to the device */
2002                 err = sb_issue_discard(sb, discard_block, next - start,
2003                                        GFP_NOFS, 0);
2004                 count += (next - start);
2005 free_extent:
2006                 freed = 0;
2007 
2008                 /*
2009                  * Clear bits in the bitmap
2010                  */
2011                 for (bit = start; bit < next; bit++) {
2012                         BUFFER_TRACE(bitmap_bh, "clear bit");
2013                         if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, group),
2014                                                 bit, bitmap_bh->b_data)) {
2015                                 ext3_error(sb, __func__,
2016                                         "bit already cleared for block "E3FSBLK,
2017                                          (unsigned long)bit);
2018                                 BUFFER_TRACE(bitmap_bh, "bit already cleared");
2019                         } else {
2020                                 freed++;
2021                         }
2022                 }
2023 
2024                 /* Update couters */
2025                 spin_lock(sb_bgl_lock(sbi, group));
2026                 le16_add_cpu(&gdp->bg_free_blocks_count, freed);
2027                 spin_unlock(sb_bgl_lock(sbi, group));
2028                 percpu_counter_add(&sbi->s_freeblocks_counter, freed);
2029 
2030                 start = next;
2031                 if (err < 0) {
2032                         if (err != -EOPNOTSUPP)
2033                                 ext3_warning(sb, __func__, "Discard command "
2034                                              "returned error %d\n", err);
2035                         break;
2036                 }
2037 
2038                 if (fatal_signal_pending(current)) {
2039                         err = -ERESTARTSYS;
2040                         break;
2041                 }
2042 
2043                 cond_resched();
2044 
2045                 /* No more suitable extents */
2046                 if (free_blocks < minblocks)
2047                         break;
2048         }
2049 
2050         /* We dirtied the bitmap block */
2051         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
2052         ret = ext3_journal_dirty_metadata(handle, bitmap_bh);
2053         if (!err)
2054                 err = ret;
2055 
2056         /* And the group descriptor block */
2057         BUFFER_TRACE(gdp_bh, "dirtied group descriptor block");
2058         ret = ext3_journal_dirty_metadata(handle, gdp_bh);
2059         if (!err)
2060                 err = ret;
2061 
2062         ext3_debug("trimmed %d blocks in the group %d\n",
2063                 count, group);
2064 
2065 err_out:
2066         if (err)
2067                 count = err;
2068         ext3_journal_stop(handle);
2069         brelse(bitmap_bh);
2070 
2071         return count;
2072 }
2073 
2074 /**
2075  * ext3_trim_fs() -- trim ioctl handle function
2076  * @sb:                 superblock for filesystem
2077  * @start:              First Byte to trim
2078  * @len:                number of Bytes to trim from start
2079  * @minlen:             minimum extent length in Bytes
2080  *
2081  * ext3_trim_fs goes through all allocation groups containing Bytes from
2082  * start to start+len. For each such a group ext3_trim_all_free function
2083  * is invoked to trim all free space.
2084  */
2085 int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range)
2086 {
2087         ext3_grpblk_t last_block, first_block;
2088         unsigned long group, first_group, last_group;
2089         struct ext3_group_desc *gdp;
2090         struct ext3_super_block *es = EXT3_SB(sb)->s_es;
2091         uint64_t start, minlen, end, trimmed = 0;
2092         ext3_fsblk_t first_data_blk =
2093                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block);
2094         ext3_fsblk_t max_blks = le32_to_cpu(es->s_blocks_count);
2095         int ret = 0;
2096 
2097         start = range->start >> sb->s_blocksize_bits;
2098         end = start + (range->len >> sb->s_blocksize_bits) - 1;
2099         minlen = range->minlen >> sb->s_blocksize_bits;
2100 
2101         if (minlen > EXT3_BLOCKS_PER_GROUP(sb) ||
2102             start >= max_blks ||
2103             range->len < sb->s_blocksize)
2104                 return -EINVAL;
2105         if (end >= max_blks)
2106                 end = max_blks - 1;
2107         if (end <= first_data_blk)
2108                 goto out;
2109         if (start < first_data_blk)
2110                 start = first_data_blk;
2111 
2112         smp_rmb();
2113 
2114         /* Determine first and last group to examine based on start and len */
2115         ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) start,
2116                                      &first_group, &first_block);
2117         ext3_get_group_no_and_offset(sb, (ext3_fsblk_t) end,
2118                                      &last_group, &last_block);
2119 
2120         /* end now represents the last block to discard in this group */
2121         end = EXT3_BLOCKS_PER_GROUP(sb) - 1;
2122 
2123         for (group = first_group; group <= last_group; group++) {
2124                 gdp = ext3_get_group_desc(sb, group, NULL);
2125                 if (!gdp)
2126                         break;
2127 
2128                 /*
2129                  * For all the groups except the last one, last block will
2130                  * always be EXT3_BLOCKS_PER_GROUP(sb)-1, so we only need to
2131                  * change it for the last group, note that last_block is
2132                  * already computed earlier by ext3_get_group_no_and_offset()
2133                  */
2134                 if (group == last_group)
2135                         end = last_block;
2136 
2137                 if (le16_to_cpu(gdp->bg_free_blocks_count) >= minlen) {
2138                         ret = ext3_trim_all_free(sb, group, first_block,
2139                                                  end, minlen);
2140                         if (ret < 0)
2141                                 break;
2142                         trimmed += ret;
2143                 }
2144 
2145                 /*
2146                  * For every group except the first one, we are sure
2147                  * that the first block to discard will be block #0.
2148                  */
2149                 first_block = 0;
2150         }
2151 
2152         if (ret > 0)
2153                 ret = 0;
2154 
2155 out:
2156         range->len = trimmed * sb->s_blocksize;
2157         return ret;
2158 }
2159 

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