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      1 /*
      2  * blkmap64_rb.c --- Simple rb-tree implementation for bitmaps
      3  *
      4  * (C)2010 Red Hat, Inc., Lukas Czerner <lczerner (at) redhat.com>
      5  *
      6  * %Begin-Header%
      7  * This file may be redistributed under the terms of the GNU Public
      8  * License.
      9  * %End-Header%
     10  */
     11 
     12 #include <stdio.h>
     13 #include <string.h>
     14 #if HAVE_UNISTD_H
     15 #include <unistd.h>
     16 #endif
     17 #include <fcntl.h>
     18 #include <time.h>
     19 #if HAVE_SYS_STAT_H
     20 #include <sys/stat.h>
     21 #endif
     22 #if HAVE_SYS_TYPES_H
     23 #include <sys/types.h>
     24 #endif
     25 
     26 #include "ext2_fs.h"
     27 #include "ext2fsP.h"
     28 #include "bmap64.h"
     29 #include "rbtree.h"
     30 
     31 #include <limits.h>
     32 
     33 struct bmap_rb_extent {
     34 	struct rb_node node;
     35 	__u64 start;
     36 	__u64 count;
     37 };
     38 
     39 struct ext2fs_rb_private {
     40 	struct rb_root root;
     41 	struct bmap_rb_extent *wcursor;
     42 	struct bmap_rb_extent *rcursor;
     43 	struct bmap_rb_extent *rcursor_next;
     44 #ifdef BMAP_STATS_OPS
     45 	__u64 mark_hit;
     46 	__u64 test_hit;
     47 #endif
     48 };
     49 
     50 inline static struct bmap_rb_extent *node_to_extent(struct rb_node *node)
     51 {
     52 	/*
     53 	 * This depends on the fact the struct rb_node is at the
     54 	 * beginning of the bmap_rb_extent structure.  We use this
     55 	 * instead of the ext2fs_rb_entry macro because it causes gcc
     56 	 * -Wall to generate a huge amount of noise.
     57 	 */
     58 	return (struct bmap_rb_extent *) node;
     59 }
     60 
     61 static int rb_insert_extent(__u64 start, __u64 count,
     62 			    struct ext2fs_rb_private *);
     63 static void rb_get_new_extent(struct bmap_rb_extent **, __u64, __u64);
     64 
     65 /* #define DEBUG_RB */
     66 
     67 #ifdef DEBUG_RB
     68 static void print_tree(struct rb_root *root)
     69 {
     70 	struct rb_node *node = NULL;
     71 	struct bmap_rb_extent *ext;
     72 
     73 	printf("\t\t\t=================================\n");
     74 	node = ext2fs_rb_first(root);
     75 	for (node = ext2fs_rb_first(root); node != NULL;
     76 	     node = ext2fs_rb_next(node)) {
     77 		ext = node_to_extent(node);
     78 		printf("\t\t\t--> (%llu -> %llu)\n",
     79 			ext->start, ext->start + ext->count);
     80 	}
     81 	printf("\t\t\t=================================\n");
     82 }
     83 
     84 static void check_tree(struct rb_root *root, const char *msg)
     85 {
     86 	struct rb_node *new_node, *node, *next;
     87 	struct bmap_rb_extent *ext, *old = NULL;
     88 
     89 	for (node = ext2fs_rb_first(root); node;
     90 	     node = ext2fs_rb_next(node)) {
     91 		ext = node_to_extent(node);
     92 		if (ext->count <= 0) {
     93 			printf("Tree Error: count is crazy\n");
     94 			printf("extent: %llu -> %llu (%u)\n", ext->start,
     95 				ext->start + ext->count, ext->count);
     96 			goto err_out;
     97 		}
     98 		if (ext->start < 0) {
     99 			printf("Tree Error: start is crazy\n");
    100 			printf("extent: %llu -> %llu (%u)\n", ext->start,
    101 				ext->start + ext->count, ext->count);
    102 			goto err_out;
    103 		}
    104 
    105 		if (old) {
    106 			if (old->start > ext->start) {
    107 				printf("Tree Error: start is crazy\n");
    108 				printf("extent: %llu -> %llu (%u)\n",
    109 					old->start, old->start + old->count,
    110 					old->count);
    111 				printf("extent next: %llu -> %llu (%u)\n",
    112 					ext->start, ext->start + ext->count,
    113 					ext->count);
    114 				goto err_out;
    115 			}
    116 			if ((old->start + old->count) >= ext->start) {
    117 				printf("Tree Error: extent is crazy\n");
    118 				printf("extent: %llu -> %llu (%u)\n",
    119 					old->start, old->start + old->count,
    120 					old->count);
    121 				printf("extent next: %llu -> %llu (%u)\n",
    122 					ext->start, ext->start + ext->count,
    123 					ext->count);
    124 				goto err_out;
    125 			}
    126 		}
    127 		old = ext;
    128 	}
    129 	return;
    130 
    131 err_out:
    132 	printf("%s\n", msg);
    133 	print_tree(root);
    134 	exit(1);
    135 }
    136 #else
    137 #define check_tree(root, msg) do {} while (0)
    138 #define print_tree(root, msg) do {} while (0)
    139 #endif
    140 
    141 static void rb_get_new_extent(struct bmap_rb_extent **ext, __u64 start,
    142 			     __u64 count)
    143 {
    144 	struct bmap_rb_extent *new_ext;
    145 	int retval;
    146 
    147 	retval = ext2fs_get_mem(sizeof (struct bmap_rb_extent),
    148 				&new_ext);
    149 	if (retval) {
    150 		perror("ext2fs_get_mem");
    151 		exit(1);
    152 	}
    153 
    154 	new_ext->start = start;
    155 	new_ext->count = count;
    156 	*ext = new_ext;
    157 }
    158 
    159 inline
    160 static void rb_free_extent(struct ext2fs_rb_private *bp,
    161 			   struct bmap_rb_extent *ext)
    162 {
    163 	if (bp->wcursor == ext)
    164 		bp->wcursor = NULL;
    165 	if (bp->rcursor == ext)
    166 		bp->rcursor = NULL;
    167 	if (bp->rcursor_next == ext)
    168 		bp->rcursor_next = NULL;
    169 	ext2fs_free_mem(&ext);
    170 }
    171 
    172 static errcode_t rb_alloc_private_data (ext2fs_generic_bitmap bitmap)
    173 {
    174 	struct ext2fs_rb_private *bp;
    175 	errcode_t	retval;
    176 
    177 	retval = ext2fs_get_mem(sizeof (struct ext2fs_rb_private), &bp);
    178 	if (retval)
    179 		return retval;
    180 
    181 	bp->root = RB_ROOT;
    182 	bp->rcursor = NULL;
    183 	bp->rcursor_next = NULL;
    184 	bp->wcursor = NULL;
    185 
    186 #ifdef BMAP_STATS_OPS
    187 	bp->test_hit = 0;
    188 	bp->mark_hit = 0;
    189 #endif
    190 
    191 	bitmap->private = (void *) bp;
    192 	return 0;
    193 }
    194 
    195 static errcode_t rb_new_bmap(ext2_filsys fs EXT2FS_ATTR((unused)),
    196 			     ext2fs_generic_bitmap bitmap)
    197 {
    198 	errcode_t	retval;
    199 
    200 	retval = rb_alloc_private_data (bitmap);
    201 	if (retval)
    202 		return retval;
    203 
    204 	return 0;
    205 }
    206 
    207 static void rb_free_tree(struct rb_root *root)
    208 {
    209 	struct bmap_rb_extent *ext;
    210 	struct rb_node *node, *next;
    211 
    212 	for (node = ext2fs_rb_first(root); node; node = next) {
    213 		next = ext2fs_rb_next(node);
    214 		ext = node_to_extent(node);
    215 		ext2fs_rb_erase(node, root);
    216 		ext2fs_free_mem(&ext);
    217 	}
    218 }
    219 
    220 static void rb_free_bmap(ext2fs_generic_bitmap bitmap)
    221 {
    222 	struct ext2fs_rb_private *bp;
    223 
    224 	bp = (struct ext2fs_rb_private *) bitmap->private;
    225 
    226 	rb_free_tree(&bp->root);
    227 	ext2fs_free_mem(&bp);
    228 	bp = 0;
    229 }
    230 
    231 static errcode_t rb_copy_bmap(ext2fs_generic_bitmap src,
    232 			      ext2fs_generic_bitmap dest)
    233 {
    234 	struct ext2fs_rb_private *src_bp, *dest_bp;
    235 	struct bmap_rb_extent *src_ext, *dest_ext;
    236 	struct rb_node *dest_node, *src_node, *dest_last, **n;
    237 	errcode_t retval = 0;
    238 
    239 	retval = rb_alloc_private_data (dest);
    240 	if (retval)
    241 		return retval;
    242 
    243 	src_bp = (struct ext2fs_rb_private *) src->private;
    244 	dest_bp = (struct ext2fs_rb_private *) dest->private;
    245 	src_bp->rcursor = NULL;
    246 	dest_bp->rcursor = NULL;
    247 
    248 	src_node = ext2fs_rb_first(&src_bp->root);
    249 	while (src_node) {
    250 		src_ext = node_to_extent(src_node);
    251 		retval = ext2fs_get_mem(sizeof (struct bmap_rb_extent),
    252 					&dest_ext);
    253 		if (retval)
    254 			break;
    255 
    256 		memcpy(dest_ext, src_ext, sizeof(struct bmap_rb_extent));
    257 
    258 		dest_node = &dest_ext->node;
    259 		n = &dest_bp->root.rb_node;
    260 
    261 		dest_last = NULL;
    262 		if (*n) {
    263 			dest_last = ext2fs_rb_last(&dest_bp->root);
    264 			n = &(dest_last)->rb_right;
    265 		}
    266 
    267 		ext2fs_rb_link_node(dest_node, dest_last, n);
    268 		ext2fs_rb_insert_color(dest_node, &dest_bp->root);
    269 
    270 		src_node = ext2fs_rb_next(src_node);
    271 	}
    272 
    273 	return retval;
    274 }
    275 
    276 static void rb_truncate(__u64 new_max, struct rb_root *root)
    277 {
    278 	struct bmap_rb_extent *ext;
    279 	struct rb_node *node;
    280 
    281 	node = ext2fs_rb_last(root);
    282 	while (node) {
    283 		ext = node_to_extent(node);
    284 
    285 		if ((ext->start + ext->count - 1) <= new_max)
    286 			break;
    287 		else if (ext->start > new_max) {
    288 			ext2fs_rb_erase(node, root);
    289 			ext2fs_free_mem(&ext);
    290 			node = ext2fs_rb_last(root);
    291 			continue;
    292 		} else
    293 			ext->count = new_max - ext->start + 1;
    294 	}
    295 }
    296 
    297 static errcode_t rb_resize_bmap(ext2fs_generic_bitmap bmap,
    298 				__u64 new_end, __u64 new_real_end)
    299 {
    300 	struct ext2fs_rb_private *bp;
    301 
    302 	if (new_real_end >= bmap->real_end) {
    303 		bmap->end = new_end;
    304 		bmap->real_end = new_real_end;
    305 		return 0;
    306 	}
    307 
    308 	bp = (struct ext2fs_rb_private *) bmap->private;
    309 	bp->rcursor = NULL;
    310 	bp->wcursor = NULL;
    311 
    312 	/* truncate tree to new_real_end size */
    313 	rb_truncate(new_real_end, &bp->root);
    314 
    315 	bmap->end = new_end;
    316 	bmap->real_end = new_real_end;
    317 	return 0;
    318 
    319 }
    320 
    321 inline static int
    322 rb_test_bit(struct ext2fs_rb_private *bp, __u64 bit)
    323 {
    324 	struct bmap_rb_extent *rcursor, *next_ext = NULL;
    325 	struct rb_node *parent = NULL, *next;
    326 	struct rb_node **n = &bp->root.rb_node;
    327 	struct bmap_rb_extent *ext;
    328 
    329 	rcursor = bp->rcursor;
    330 	if (!rcursor)
    331 		goto search_tree;
    332 
    333 	if (bit >= rcursor->start && bit < rcursor->start + rcursor->count) {
    334 #ifdef BMAP_STATS_OPS
    335 		bp->test_hit++;
    336 #endif
    337 		return 1;
    338 	}
    339 
    340 	next_ext = bp->rcursor_next;
    341 	if (!next_ext) {
    342 		next = ext2fs_rb_next(&rcursor->node);
    343 		if (next)
    344 			next_ext = node_to_extent(next);
    345 		bp->rcursor_next = next_ext;
    346 	}
    347 	if (next_ext) {
    348 		if ((bit >= rcursor->start + rcursor->count) &&
    349 		    (bit < next_ext->start)) {
    350 #ifdef BMAP_STATS_OPS
    351 			bp->test_hit++;
    352 #endif
    353 			return 0;
    354 		}
    355 	}
    356 	bp->rcursor = NULL;
    357 	bp->rcursor_next = NULL;
    358 
    359 	rcursor = bp->wcursor;
    360 	if (!rcursor)
    361 		goto search_tree;
    362 
    363 	if (bit >= rcursor->start && bit < rcursor->start + rcursor->count)
    364 		return 1;
    365 
    366 search_tree:
    367 
    368 	while (*n) {
    369 		parent = *n;
    370 		ext = node_to_extent(parent);
    371 		if (bit < ext->start)
    372 			n = &(*n)->rb_left;
    373 		else if (bit >= (ext->start + ext->count))
    374 			n = &(*n)->rb_right;
    375 		else {
    376 			bp->rcursor = ext;
    377 			bp->rcursor_next = NULL;
    378 			return 1;
    379 		}
    380 	}
    381 	return 0;
    382 }
    383 
    384 static int rb_insert_extent(__u64 start, __u64 count,
    385 			    struct ext2fs_rb_private *bp)
    386 {
    387 	struct rb_root *root = &bp->root;
    388 	struct rb_node *parent = NULL, **n = &root->rb_node;
    389 	struct rb_node *new_node, *node, *next;
    390 	struct bmap_rb_extent *new_ext;
    391 	struct bmap_rb_extent *ext;
    392 	int retval = 0;
    393 
    394 	bp->rcursor_next = NULL;
    395 	ext = bp->wcursor;
    396 	if (ext) {
    397 		if (start >= ext->start &&
    398 		    start <= (ext->start + ext->count)) {
    399 #ifdef BMAP_STATS_OPS
    400 			bp->mark_hit++;
    401 #endif
    402 			goto got_extent;
    403 		}
    404 	}
    405 
    406 	while (*n) {
    407 		parent = *n;
    408 		ext = node_to_extent(parent);
    409 
    410 		if (start < ext->start) {
    411 			n = &(*n)->rb_left;
    412 		} else if (start > (ext->start + ext->count)) {
    413 			n = &(*n)->rb_right;
    414 		} else {
    415 got_extent:
    416 			if ((start + count) <= (ext->start + ext->count))
    417 				return 1;
    418 
    419 			if ((ext->start + ext->count) == start)
    420 				retval = 0;
    421 			else
    422 				retval = 1;
    423 
    424 			count += (start - ext->start);
    425 			start = ext->start;
    426 			new_ext = ext;
    427 			new_node = &ext->node;
    428 
    429 			goto skip_insert;
    430 		}
    431 	}
    432 
    433 	rb_get_new_extent(&new_ext, start, count);
    434 
    435 	new_node = &new_ext->node;
    436 	ext2fs_rb_link_node(new_node, parent, n);
    437 	ext2fs_rb_insert_color(new_node, root);
    438 	bp->wcursor = new_ext;
    439 
    440 	node = ext2fs_rb_prev(new_node);
    441 	if (node) {
    442 		ext = node_to_extent(node);
    443 		if ((ext->start + ext->count) == start) {
    444 			start = ext->start;
    445 			count += ext->count;
    446 			ext2fs_rb_erase(node, root);
    447 			rb_free_extent(bp, ext);
    448 		}
    449 	}
    450 
    451 skip_insert:
    452 	/* See if we can merge extent to the right */
    453 	for (node = ext2fs_rb_next(new_node); node != NULL; node = next) {
    454 		next = ext2fs_rb_next(node);
    455 		ext = node_to_extent(node);
    456 
    457 		if ((ext->start + ext->count) <= start)
    458 			continue;
    459 
    460 		/* No more merging */
    461 		if ((start + count) < ext->start)
    462 			break;
    463 
    464 		/* ext is embedded in new_ext interval */
    465 		if ((start + count) >= (ext->start + ext->count)) {
    466 			ext2fs_rb_erase(node, root);
    467 			rb_free_extent(bp, ext);
    468 			continue;
    469 		} else {
    470 		/* merge ext with new_ext */
    471 			count += ((ext->start + ext->count) -
    472 				  (start + count));
    473 			ext2fs_rb_erase(node, root);
    474 			rb_free_extent(bp, ext);
    475 			break;
    476 		}
    477 	}
    478 
    479 	new_ext->start = start;
    480 	new_ext->count = count;
    481 
    482 	return retval;
    483 }
    484 
    485 static int rb_remove_extent(__u64 start, __u64 count,
    486 			    struct ext2fs_rb_private *bp)
    487 {
    488 	struct rb_root *root = &bp->root;
    489 	struct rb_node *parent = NULL, **n = &root->rb_node;
    490 	struct rb_node *node;
    491 	struct bmap_rb_extent *ext;
    492 	__u64 new_start, new_count;
    493 	int retval = 0;
    494 
    495 	if (EXT2FS_RB_EMPTY_ROOT(root))
    496 		return 0;
    497 
    498 	while (*n) {
    499 		parent = *n;
    500 		ext = node_to_extent(parent);
    501 		if (start < ext->start) {
    502 			n = &(*n)->rb_left;
    503 			continue;
    504 		} else if (start >= (ext->start + ext->count)) {
    505 			n = &(*n)->rb_right;
    506 			continue;
    507 		}
    508 
    509 		if ((start > ext->start) &&
    510 		    (start + count) < (ext->start + ext->count)) {
    511 			/* We have to split extent into two */
    512 			new_start = start + count;
    513 			new_count = (ext->start + ext->count) - new_start;
    514 
    515 			ext->count = start - ext->start;
    516 
    517 			rb_insert_extent(new_start, new_count, bp);
    518 			return 1;
    519 		}
    520 
    521 		if ((start + count) >= (ext->start + ext->count)) {
    522 			ext->count = start - ext->start;
    523 			retval = 1;
    524 		}
    525 
    526 		if (0 == ext->count) {
    527 			parent = ext2fs_rb_next(&ext->node);
    528 			ext2fs_rb_erase(&ext->node, root);
    529 			rb_free_extent(bp, ext);
    530 			break;
    531 		}
    532 
    533 		if (start == ext->start) {
    534 			ext->start += count;
    535 			ext->count -= count;
    536 			return 1;
    537 		}
    538 	}
    539 
    540 	/* See if we should delete or truncate extent on the right */
    541 	for (; parent != NULL; parent = node) {
    542 		node = ext2fs_rb_next(parent);
    543 		ext = node_to_extent(parent);
    544 		if ((ext->start + ext->count) <= start)
    545 			continue;
    546 
    547 		/* No more extents to be removed/truncated */
    548 		if ((start + count) < ext->start)
    549 			break;
    550 
    551 		/* The entire extent is within the region to be removed */
    552 		if ((start + count) >= (ext->start + ext->count)) {
    553 			ext2fs_rb_erase(parent, root);
    554 			rb_free_extent(bp, ext);
    555 			retval = 1;
    556 			continue;
    557 		} else {
    558 			/* modify the last extent in reigon to be removed */
    559 			ext->count -= ((start + count) - ext->start);
    560 			ext->start = start + count;
    561 			retval = 1;
    562 			break;
    563 		}
    564 	}
    565 
    566 	return retval;
    567 }
    568 
    569 static int rb_mark_bmap(ext2fs_generic_bitmap bitmap, __u64 arg)
    570 {
    571 	struct ext2fs_rb_private *bp;
    572 
    573 	bp = (struct ext2fs_rb_private *) bitmap->private;
    574 	arg -= bitmap->start;
    575 
    576 	return rb_insert_extent(arg, 1, bp);
    577 }
    578 
    579 static int rb_unmark_bmap(ext2fs_generic_bitmap bitmap, __u64 arg)
    580 {
    581 	struct ext2fs_rb_private *bp;
    582 	int retval;
    583 
    584 	bp = (struct ext2fs_rb_private *) bitmap->private;
    585 	arg -= bitmap->start;
    586 
    587 	retval = rb_remove_extent(arg, 1, bp);
    588 	check_tree(&bp->root, __func__);
    589 
    590 	return retval;
    591 }
    592 
    593 inline
    594 static int rb_test_bmap(ext2fs_generic_bitmap bitmap, __u64 arg)
    595 {
    596 	struct ext2fs_rb_private *bp;
    597 
    598 	bp = (struct ext2fs_rb_private *) bitmap->private;
    599 	arg -= bitmap->start;
    600 
    601 	return rb_test_bit(bp, arg);
    602 }
    603 
    604 static void rb_mark_bmap_extent(ext2fs_generic_bitmap bitmap, __u64 arg,
    605 				unsigned int num)
    606 {
    607 	struct ext2fs_rb_private *bp;
    608 
    609 	bp = (struct ext2fs_rb_private *) bitmap->private;
    610 	arg -= bitmap->start;
    611 
    612 	rb_insert_extent(arg, num, bp);
    613 }
    614 
    615 static void rb_unmark_bmap_extent(ext2fs_generic_bitmap bitmap, __u64 arg,
    616 				  unsigned int num)
    617 {
    618 	struct ext2fs_rb_private *bp;
    619 
    620 	bp = (struct ext2fs_rb_private *) bitmap->private;
    621 	arg -= bitmap->start;
    622 
    623 	rb_remove_extent(arg, num, bp);
    624 	check_tree(&bp->root, __func__);
    625 }
    626 
    627 static int rb_test_clear_bmap_extent(ext2fs_generic_bitmap bitmap,
    628 				     __u64 start, unsigned int len)
    629 {
    630 	struct rb_node *parent = NULL, **n;
    631 	struct rb_node *node, *next;
    632 	struct ext2fs_rb_private *bp;
    633 	struct bmap_rb_extent *ext;
    634 	int retval = 1;
    635 
    636 	bp = (struct ext2fs_rb_private *) bitmap->private;
    637 	n = &bp->root.rb_node;
    638 	start -= bitmap->start;
    639 
    640 	if ((len == 0) || EXT2FS_RB_EMPTY_ROOT(&bp->root))
    641 		return 1;
    642 
    643 	/*
    644 	 * If we find nothing, we should examine whole extent, but
    645 	 * when we find match, the extent is not clean, thus be return
    646 	 * false.
    647 	 */
    648 	while (*n) {
    649 		parent = *n;
    650 		ext = node_to_extent(parent);
    651 		if (start < ext->start) {
    652 			n = &(*n)->rb_left;
    653 		} else if (start >= (ext->start + ext->count)) {
    654 			n = &(*n)->rb_right;
    655 		} else {
    656 			/*
    657 			 * We found extent int the tree -> extent is not
    658 			 * clean
    659 			 */
    660 			return 0;
    661 		}
    662 	}
    663 
    664 	node = parent;
    665 	while (node) {
    666 		next = ext2fs_rb_next(node);
    667 		ext = node_to_extent(node);
    668 		node = next;
    669 
    670 		if ((ext->start + ext->count) <= start)
    671 			continue;
    672 
    673 		/* No more merging */
    674 		if ((start + len) <= ext->start)
    675 			break;
    676 
    677 		retval = 0;
    678 		break;
    679 	}
    680 	return retval;
    681 }
    682 
    683 static errcode_t rb_set_bmap_range(ext2fs_generic_bitmap bitmap,
    684 				     __u64 start, size_t num, void *in)
    685 {
    686 	struct ext2fs_rb_private *bp;
    687 	unsigned char *cp = in;
    688 	size_t i;
    689 	int first_set = -1;
    690 
    691 	bp = (struct ext2fs_rb_private *) bitmap->private;
    692 
    693 	for (i = 0; i < num; i++) {
    694 		if ((i & 7) == 0) {
    695 			unsigned char c = cp[i/8];
    696 			if (c == 0xFF) {
    697 				if (first_set == -1)
    698 					first_set = i;
    699 				i += 7;
    700 				continue;
    701 			}
    702 			if ((c == 0x00) && (first_set == -1)) {
    703 				i += 7;
    704 				continue;
    705 			}
    706 		}
    707 		if (ext2fs_test_bit(i, in)) {
    708 			if (first_set == -1)
    709 				first_set = i;
    710 			continue;
    711 		}
    712 		if (first_set == -1)
    713 			continue;
    714 
    715 		rb_insert_extent(start + first_set - bitmap->start,
    716 				 i - first_set, bp);
    717 		first_set = -1;
    718 	}
    719 	if (first_set != -1)
    720 		rb_insert_extent(start + first_set - bitmap->start,
    721 				 num - first_set, bp);
    722 
    723 	return 0;
    724 }
    725 
    726 static errcode_t rb_get_bmap_range(ext2fs_generic_bitmap bitmap,
    727 				     __u64 start, size_t num, void *out)
    728 {
    729 
    730 	struct rb_node *parent = NULL, *next, **n;
    731 	struct ext2fs_rb_private *bp;
    732 	struct bmap_rb_extent *ext;
    733 	int count;
    734 	__u64 pos;
    735 
    736 	bp = (struct ext2fs_rb_private *) bitmap->private;
    737 	n = &bp->root.rb_node;
    738 	start -= bitmap->start;
    739 
    740 	if (EXT2FS_RB_EMPTY_ROOT(&bp->root))
    741 		return 0;
    742 
    743 	while (*n) {
    744 		parent = *n;
    745 		ext = node_to_extent(parent);
    746 		if (start < ext->start) {
    747 			n = &(*n)->rb_left;
    748 		} else if (start >= (ext->start + ext->count)) {
    749 			n = &(*n)->rb_right;
    750 		} else
    751 			break;
    752 	}
    753 
    754 	memset(out, 0, (num + 7) >> 3);
    755 
    756 	for (; parent != NULL; parent = next) {
    757 		next = ext2fs_rb_next(parent);
    758 		ext = node_to_extent(parent);
    759 
    760 		pos = ext->start;
    761 		count = ext->count;
    762 		if (pos >= start + num)
    763 			break;
    764 		if (pos < start) {
    765 			count -= start - pos;
    766 			if (count < 0)
    767 				continue;
    768 			pos = start;
    769 		}
    770 		if (pos + count > start + num)
    771 			count = start + num - pos;
    772 
    773 		while (count > 0) {
    774 			if ((count >= 8) &&
    775 			    ((pos - start) % 8) == 0) {
    776 				int nbytes = count >> 3;
    777 				int offset = (pos - start) >> 3;
    778 
    779 				memset(((char *) out) + offset, 0xFF, nbytes);
    780 				pos += nbytes << 3;
    781 				count -= nbytes << 3;
    782 				continue;
    783 			}
    784 			ext2fs_fast_set_bit64((pos - start), out);
    785 			pos++;
    786 			count--;
    787 		}
    788 	}
    789 	return 0;
    790 }
    791 
    792 static void rb_clear_bmap(ext2fs_generic_bitmap bitmap)
    793 {
    794 	struct ext2fs_rb_private *bp;
    795 
    796 	bp = (struct ext2fs_rb_private *) bitmap->private;
    797 
    798 	rb_free_tree(&bp->root);
    799 	bp->rcursor = NULL;
    800 	bp->rcursor_next = NULL;
    801 	bp->wcursor = NULL;
    802 }
    803 
    804 #ifdef BMAP_STATS
    805 static void rb_print_stats(ext2fs_generic_bitmap bitmap)
    806 {
    807 	struct ext2fs_rb_private *bp;
    808 	struct rb_node *node = NULL;
    809 	struct bmap_rb_extent *ext;
    810 	__u64 count = 0;
    811 	__u64 max_size = 0;
    812 	__u64 min_size = ULONG_MAX;
    813 	__u64 size = 0, avg_size = 0;
    814 	double eff;
    815 #ifdef BMAP_STATS_OPS
    816 	__u64 mark_all, test_all;
    817 	double m_hit = 0.0, t_hit = 0.0;
    818 #endif
    819 
    820 	bp = (struct ext2fs_rb_private *) bitmap->private;
    821 
    822 	node = ext2fs_rb_first(&bp->root);
    823 	for (node = ext2fs_rb_first(&bp->root); node != NULL;
    824 	     node = ext2fs_rb_next(node)) {
    825 		ext = node_to_extent(node);
    826 		count++;
    827 		if (ext->count > max_size)
    828 			max_size = ext->count;
    829 		if (ext->count < min_size)
    830 			min_size = ext->count;
    831 		size += ext->count;
    832 	}
    833 
    834 	if (count)
    835 		avg_size = size / count;
    836 	if (min_size == ULONG_MAX)
    837 		min_size = 0;
    838 	eff = (double)((count * sizeof(struct bmap_rb_extent)) << 3) /
    839 	      (bitmap->real_end - bitmap->start);
    840 #ifdef BMAP_STATS_OPS
    841 	mark_all = bitmap->stats.mark_count + bitmap->stats.mark_ext_count;
    842 	test_all = bitmap->stats.test_count + bitmap->stats.test_ext_count;
    843 	if (mark_all)
    844 		m_hit = ((double)bp->mark_hit / mark_all) * 100;
    845 	if (test_all)
    846 		t_hit = ((double)bp->test_hit / test_all) * 100;
    847 
    848 	fprintf(stderr, "%16llu cache hits on test (%.2f%%)\n"
    849 		"%16llu cache hits on mark (%.2f%%)\n",
    850 		bp->test_hit, t_hit, bp->mark_hit, m_hit);
    851 #endif
    852 	fprintf(stderr, "%16llu extents (%llu bytes)\n",
    853 		count, ((count * sizeof(struct bmap_rb_extent)) +
    854 			sizeof(struct ext2fs_rb_private)));
    855  	fprintf(stderr, "%16llu bits minimum size\n",
    856 		min_size);
    857 	fprintf(stderr, "%16llu bits maximum size\n"
    858 		"%16llu bits average size\n",
    859 		max_size, avg_size);
    860 	fprintf(stderr, "%16llu bits set in bitmap (out of %llu)\n", size,
    861 		bitmap->real_end - bitmap->start);
    862 	fprintf(stderr,
    863 		"%16.4lf memory / bitmap bit memory ratio (bitarray = 1)\n",
    864 		eff);
    865 }
    866 #else
    867 static void rb_print_stats(ext2fs_generic_bitmap bitmap){}
    868 #endif
    869 
    870 struct ext2_bitmap_ops ext2fs_blkmap64_rbtree = {
    871 	.type = EXT2FS_BMAP64_RBTREE,
    872 	.new_bmap = rb_new_bmap,
    873 	.free_bmap = rb_free_bmap,
    874 	.copy_bmap = rb_copy_bmap,
    875 	.resize_bmap = rb_resize_bmap,
    876 	.mark_bmap = rb_mark_bmap,
    877 	.unmark_bmap = rb_unmark_bmap,
    878 	.test_bmap = rb_test_bmap,
    879 	.test_clear_bmap_extent = rb_test_clear_bmap_extent,
    880 	.mark_bmap_extent = rb_mark_bmap_extent,
    881 	.unmark_bmap_extent = rb_unmark_bmap_extent,
    882 	.set_bmap_range = rb_set_bmap_range,
    883 	.get_bmap_range = rb_get_bmap_range,
    884 	.clear_bmap = rb_clear_bmap,
    885 	.print_stats = rb_print_stats,
    886 };
    887