1/*
   2 *  linux/fs/ext2/balloc.c
   3 *
   4 * Copyright (C) 1992, 1993, 1994, 1995
   5 * Remy Card (card@masi.ibp.fr)
   6 * Laboratoire MASI - Institut Blaise Pascal
   7 * Universite Pierre et Marie Curie (Paris VI)
   8 *
   9 *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
  10 *  Big-endian to little-endian byte-swapping/bitmaps by
  11 *        David S. Miller (davem@caip.rutgers.edu), 1995
  12 */
  13
  14#include "ext2.h"
  15#include <linux/quotaops.h>
  16#include <linux/slab.h>
  17#include <linux/sched.h>
 
  18#include <linux/buffer_head.h>
  19#include <linux/capability.h>
  20
  21/*
  22 * balloc.c contains the blocks allocation and deallocation routines
  23 */
  24
  25/*
  26 * The free blocks are managed by bitmaps.  A file system contains several
  27 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  28 * block for inodes, N blocks for the inode table and data blocks.
  29 *
  30 * The file system contains group descriptors which are located after the
  31 * super block.  Each descriptor contains the number of the bitmap block and
  32 * the free blocks count in the block.  The descriptors are loaded in memory
  33 * when a file system is mounted (see ext2_fill_super).
  34 */
  35
  36
  37#define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)
  38
  39struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
  40					     unsigned int block_group,
  41					     struct buffer_head ** bh)
  42{
  43	unsigned long group_desc;
  44	unsigned long offset;
  45	struct ext2_group_desc * desc;
  46	struct ext2_sb_info *sbi = EXT2_SB(sb);
  47
  48	if (block_group >= sbi->s_groups_count) {
  49		ext2_error (sb, "ext2_get_group_desc",
  50			    "block_group >= groups_count - "
  51			    "block_group = %d, groups_count = %lu",
  52			    block_group, sbi->s_groups_count);
  53
  54		return NULL;
  55	}
  56
  57	group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
  58	offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
  59	if (!sbi->s_group_desc[group_desc]) {
  60		ext2_error (sb, "ext2_get_group_desc",
  61			    "Group descriptor not loaded - "
  62			    "block_group = %d, group_desc = %lu, desc = %lu",
  63			     block_group, group_desc, offset);
  64		return NULL;
  65	}
  66
  67	desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  68	if (bh)
  69		*bh = sbi->s_group_desc[group_desc];
  70	return desc + offset;
  71}
  72
  73static int ext2_valid_block_bitmap(struct super_block *sb,
  74					struct ext2_group_desc *desc,
  75					unsigned int block_group,
  76					struct buffer_head *bh)
  77{
  78	ext2_grpblk_t offset;
  79	ext2_grpblk_t next_zero_bit;
  80	ext2_fsblk_t bitmap_blk;
  81	ext2_fsblk_t group_first_block;
 
  82
  83	group_first_block = ext2_group_first_block_no(sb, block_group);
 
  84
  85	/* check whether block bitmap block number is set */
  86	bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
  87	offset = bitmap_blk - group_first_block;
  88	if (!ext2_test_bit(offset, bh->b_data))
 
  89		/* bad block bitmap */
  90		goto err_out;
  91
  92	/* check whether the inode bitmap block number is set */
  93	bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
  94	offset = bitmap_blk - group_first_block;
  95	if (!ext2_test_bit(offset, bh->b_data))
 
  96		/* bad block bitmap */
  97		goto err_out;
  98
  99	/* check whether the inode table block number is set */
 100	bitmap_blk = le32_to_cpu(desc->bg_inode_table);
 101	offset = bitmap_blk - group_first_block;
 
 
 
 102	next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
 103				offset + EXT2_SB(sb)->s_itb_per_group,
 104				offset);
 105	if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
 106		/* good bitmap for inode tables */
 107		return 1;
 108
 109err_out:
 110	ext2_error(sb, __func__,
 111			"Invalid block bitmap - "
 112			"block_group = %d, block = %lu",
 113			block_group, bitmap_blk);
 114	return 0;
 115}
 116
 117/*
 118 * Read the bitmap for a given block_group,and validate the
 119 * bits for block/inode/inode tables are set in the bitmaps
 120 *
 121 * Return buffer_head on success or NULL in case of failure.
 122 */
 123static struct buffer_head *
 124read_block_bitmap(struct super_block *sb, unsigned int block_group)
 125{
 126	struct ext2_group_desc * desc;
 127	struct buffer_head * bh = NULL;
 128	ext2_fsblk_t bitmap_blk;
 
 129
 130	desc = ext2_get_group_desc(sb, block_group, NULL);
 131	if (!desc)
 132		return NULL;
 133	bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
 134	bh = sb_getblk(sb, bitmap_blk);
 135	if (unlikely(!bh)) {
 136		ext2_error(sb, __func__,
 137			    "Cannot read block bitmap - "
 138			    "block_group = %d, block_bitmap = %u",
 139			    block_group, le32_to_cpu(desc->bg_block_bitmap));
 140		return NULL;
 141	}
 142	if (likely(bh_uptodate_or_lock(bh)))
 
 143		return bh;
 144
 145	if (bh_submit_read(bh) < 0) {
 146		brelse(bh);
 147		ext2_error(sb, __func__,
 148			    "Cannot read block bitmap - "
 149			    "block_group = %d, block_bitmap = %u",
 150			    block_group, le32_to_cpu(desc->bg_block_bitmap));
 151		return NULL;
 152	}
 153
 154	ext2_valid_block_bitmap(sb, desc, block_group, bh);
 155	/*
 156	 * file system mounted not to panic on error, continue with corrupt
 157	 * bitmap
 158	 */
 159	return bh;
 160}
 161
 162static void release_blocks(struct super_block *sb, int count)
 163{
 164	if (count) {
 165		struct ext2_sb_info *sbi = EXT2_SB(sb);
 166
 167		percpu_counter_add(&sbi->s_freeblocks_counter, count);
 168		sb->s_dirt = 1;
 169	}
 170}
 171
 172static void group_adjust_blocks(struct super_block *sb, int group_no,
 173	struct ext2_group_desc *desc, struct buffer_head *bh, int count)
 174{
 175	if (count) {
 176		struct ext2_sb_info *sbi = EXT2_SB(sb);
 177		unsigned free_blocks;
 178
 179		spin_lock(sb_bgl_lock(sbi, group_no));
 180		free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
 181		desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
 182		spin_unlock(sb_bgl_lock(sbi, group_no));
 183		sb->s_dirt = 1;
 184		mark_buffer_dirty(bh);
 185	}
 186}
 187
 188/*
 189 * The reservation window structure operations
 190 * --------------------------------------------
 191 * Operations include:
 192 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 193 *
 194 * We use a red-black tree to represent per-filesystem reservation
 195 * windows.
 196 *
 197 */
 198
 199/**
 200 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
 201 * @rb_root:		root of per-filesystem reservation rb tree
 202 * @verbose:		verbose mode
 203 * @fn:			function which wishes to dump the reservation map
 204 *
 205 * If verbose is turned on, it will print the whole block reservation
 206 * windows(start, end). Otherwise, it will only print out the "bad" windows,
 207 * those windows that overlap with their immediate neighbors.
 208 */
 209#if 1
 210static void __rsv_window_dump(struct rb_root *root, int verbose,
 211			      const char *fn)
 212{
 213	struct rb_node *n;
 214	struct ext2_reserve_window_node *rsv, *prev;
 215	int bad;
 216
 217restart:
 218	n = rb_first(root);
 219	bad = 0;
 220	prev = NULL;
 221
 222	printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 223	while (n) {
 224		rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
 225		if (verbose)
 226			printk("reservation window 0x%p "
 227				"start: %lu, end: %lu\n",
 228				rsv, rsv->rsv_start, rsv->rsv_end);
 229		if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 230			printk("Bad reservation %p (start >= end)\n",
 231			       rsv);
 232			bad = 1;
 233		}
 234		if (prev && prev->rsv_end >= rsv->rsv_start) {
 235			printk("Bad reservation %p (prev->end >= start)\n",
 236			       rsv);
 237			bad = 1;
 238		}
 239		if (bad) {
 240			if (!verbose) {
 241				printk("Restarting reservation walk in verbose mode\n");
 242				verbose = 1;
 243				goto restart;
 244			}
 245		}
 246		n = rb_next(n);
 247		prev = rsv;
 248	}
 249	printk("Window map complete.\n");
 250	BUG_ON(bad);
 251}
 252#define rsv_window_dump(root, verbose) \
 253	__rsv_window_dump((root), (verbose), __func__)
 254#else
 255#define rsv_window_dump(root, verbose) do {} while (0)
 256#endif
 257
 258/**
 259 * goal_in_my_reservation()
 260 * @rsv:		inode's reservation window
 261 * @grp_goal:		given goal block relative to the allocation block group
 262 * @group:		the current allocation block group
 263 * @sb:			filesystem super block
 264 *
 265 * Test if the given goal block (group relative) is within the file's
 266 * own block reservation window range.
 267 *
 268 * If the reservation window is outside the goal allocation group, return 0;
 269 * grp_goal (given goal block) could be -1, which means no specific
 270 * goal block. In this case, always return 1.
 271 * If the goal block is within the reservation window, return 1;
 272 * otherwise, return 0;
 273 */
 274static int
 275goal_in_my_reservation(struct ext2_reserve_window *rsv, ext2_grpblk_t grp_goal,
 276			unsigned int group, struct super_block * sb)
 277{
 278	ext2_fsblk_t group_first_block, group_last_block;
 279
 280	group_first_block = ext2_group_first_block_no(sb, group);
 281	group_last_block = group_first_block + EXT2_BLOCKS_PER_GROUP(sb) - 1;
 282
 283	if ((rsv->_rsv_start > group_last_block) ||
 284	    (rsv->_rsv_end < group_first_block))
 285		return 0;
 286	if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
 287		|| (grp_goal + group_first_block > rsv->_rsv_end)))
 288		return 0;
 289	return 1;
 290}
 291
 292/**
 293 * search_reserve_window()
 294 * @rb_root:		root of reservation tree
 295 * @goal:		target allocation block
 296 *
 297 * Find the reserved window which includes the goal, or the previous one
 298 * if the goal is not in any window.
 299 * Returns NULL if there are no windows or if all windows start after the goal.
 300 */
 301static struct ext2_reserve_window_node *
 302search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
 303{
 304	struct rb_node *n = root->rb_node;
 305	struct ext2_reserve_window_node *rsv;
 306
 307	if (!n)
 308		return NULL;
 309
 310	do {
 311		rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
 312
 313		if (goal < rsv->rsv_start)
 314			n = n->rb_left;
 315		else if (goal > rsv->rsv_end)
 316			n = n->rb_right;
 317		else
 318			return rsv;
 319	} while (n);
 320	/*
 321	 * We've fallen off the end of the tree: the goal wasn't inside
 322	 * any particular node.  OK, the previous node must be to one
 323	 * side of the interval containing the goal.  If it's the RHS,
 324	 * we need to back up one.
 325	 */
 326	if (rsv->rsv_start > goal) {
 327		n = rb_prev(&rsv->rsv_node);
 328		rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
 329	}
 330	return rsv;
 331}
 332
 333/*
 334 * ext2_rsv_window_add() -- Insert a window to the block reservation rb tree.
 335 * @sb:			super block
 336 * @rsv:		reservation window to add
 337 *
 338 * Must be called with rsv_lock held.
 339 */
 340void ext2_rsv_window_add(struct super_block *sb,
 341		    struct ext2_reserve_window_node *rsv)
 342{
 343	struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
 344	struct rb_node *node = &rsv->rsv_node;
 345	ext2_fsblk_t start = rsv->rsv_start;
 346
 347	struct rb_node ** p = &root->rb_node;
 348	struct rb_node * parent = NULL;
 349	struct ext2_reserve_window_node *this;
 350
 351	while (*p)
 352	{
 353		parent = *p;
 354		this = rb_entry(parent, struct ext2_reserve_window_node, rsv_node);
 355
 356		if (start < this->rsv_start)
 357			p = &(*p)->rb_left;
 358		else if (start > this->rsv_end)
 359			p = &(*p)->rb_right;
 360		else {
 361			rsv_window_dump(root, 1);
 362			BUG();
 363		}
 364	}
 365
 366	rb_link_node(node, parent, p);
 367	rb_insert_color(node, root);
 368}
 369
 370/**
 371 * rsv_window_remove() -- unlink a window from the reservation rb tree
 372 * @sb:			super block
 373 * @rsv:		reservation window to remove
 374 *
 375 * Mark the block reservation window as not allocated, and unlink it
 376 * from the filesystem reservation window rb tree. Must be called with
 377 * rsv_lock held.
 378 */
 379static void rsv_window_remove(struct super_block *sb,
 380			      struct ext2_reserve_window_node *rsv)
 381{
 382	rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 383	rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 384	rsv->rsv_alloc_hit = 0;
 385	rb_erase(&rsv->rsv_node, &EXT2_SB(sb)->s_rsv_window_root);
 386}
 387
 388/*
 389 * rsv_is_empty() -- Check if the reservation window is allocated.
 390 * @rsv:		given reservation window to check
 391 *
 392 * returns 1 if the end block is EXT2_RESERVE_WINDOW_NOT_ALLOCATED.
 393 */
 394static inline int rsv_is_empty(struct ext2_reserve_window *rsv)
 395{
 396	/* a valid reservation end block could not be 0 */
 397	return (rsv->_rsv_end == EXT2_RESERVE_WINDOW_NOT_ALLOCATED);
 398}
 399
 400/**
 401 * ext2_init_block_alloc_info()
 402 * @inode:		file inode structure
 403 *
 404 * Allocate and initialize the  reservation window structure, and
 405 * link the window to the ext2 inode structure at last
 406 *
 407 * The reservation window structure is only dynamically allocated
 408 * and linked to ext2 inode the first time the open file
 409 * needs a new block. So, before every ext2_new_block(s) call, for
 410 * regular files, we should check whether the reservation window
 411 * structure exists or not. In the latter case, this function is called.
 412 * Fail to do so will result in block reservation being turned off for that
 413 * open file.
 414 *
 415 * This function is called from ext2_get_blocks_handle(), also called
 416 * when setting the reservation window size through ioctl before the file
 417 * is open for write (needs block allocation).
 418 *
 419 * Needs truncate_mutex protection prior to calling this function.
 420 */
 421void ext2_init_block_alloc_info(struct inode *inode)
 422{
 423	struct ext2_inode_info *ei = EXT2_I(inode);
 424	struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
 425	struct super_block *sb = inode->i_sb;
 426
 427	block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
 428	if (block_i) {
 429		struct ext2_reserve_window_node *rsv = &block_i->rsv_window_node;
 430
 431		rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 432		rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
 433
 434	 	/*
 435		 * if filesystem is mounted with NORESERVATION, the goal
 436		 * reservation window size is set to zero to indicate
 437		 * block reservation is off
 438		 */
 439		if (!test_opt(sb, RESERVATION))
 440			rsv->rsv_goal_size = 0;
 441		else
 442			rsv->rsv_goal_size = EXT2_DEFAULT_RESERVE_BLOCKS;
 443		rsv->rsv_alloc_hit = 0;
 444		block_i->last_alloc_logical_block = 0;
 445		block_i->last_alloc_physical_block = 0;
 446	}
 447	ei->i_block_alloc_info = block_i;
 448}
 449
 450/**
 451 * ext2_discard_reservation()
 452 * @inode:		inode
 453 *
 454 * Discard(free) block reservation window on last file close, or truncate
 455 * or at last iput().
 456 *
 457 * It is being called in three cases:
 458 * 	ext2_release_file(): last writer closes the file
 459 * 	ext2_clear_inode(): last iput(), when nobody links to this file.
 460 * 	ext2_truncate(): when the block indirect map is about to change.
 461 */
 462void ext2_discard_reservation(struct inode *inode)
 463{
 464	struct ext2_inode_info *ei = EXT2_I(inode);
 465	struct ext2_block_alloc_info *block_i = ei->i_block_alloc_info;
 466	struct ext2_reserve_window_node *rsv;
 467	spinlock_t *rsv_lock = &EXT2_SB(inode->i_sb)->s_rsv_window_lock;
 468
 469	if (!block_i)
 470		return;
 471
 472	rsv = &block_i->rsv_window_node;
 473	if (!rsv_is_empty(&rsv->rsv_window)) {
 474		spin_lock(rsv_lock);
 475		if (!rsv_is_empty(&rsv->rsv_window))
 476			rsv_window_remove(inode->i_sb, rsv);
 477		spin_unlock(rsv_lock);
 478	}
 479}
 480
 481/**
 482 * ext2_free_blocks_sb() -- Free given blocks and update quota and i_blocks
 483 * @inode:		inode
 484 * @block:		start physcial block to free
 485 * @count:		number of blocks to free
 486 */
 487void ext2_free_blocks (struct inode * inode, unsigned long block,
 488		       unsigned long count)
 489{
 490	struct buffer_head *bitmap_bh = NULL;
 491	struct buffer_head * bh2;
 492	unsigned long block_group;
 493	unsigned long bit;
 494	unsigned long i;
 495	unsigned long overflow;
 496	struct super_block * sb = inode->i_sb;
 497	struct ext2_sb_info * sbi = EXT2_SB(sb);
 498	struct ext2_group_desc * desc;
 499	struct ext2_super_block * es = sbi->s_es;
 500	unsigned freed = 0, group_freed;
 501
 502	if (block < le32_to_cpu(es->s_first_data_block) ||
 503	    block + count < block ||
 504	    block + count > le32_to_cpu(es->s_blocks_count)) {
 505		ext2_error (sb, "ext2_free_blocks",
 506			    "Freeing blocks not in datazone - "
 507			    "block = %lu, count = %lu", block, count);
 508		goto error_return;
 509	}
 510
 511	ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 512
 513do_more:
 514	overflow = 0;
 515	block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 516		      EXT2_BLOCKS_PER_GROUP(sb);
 517	bit = (block - le32_to_cpu(es->s_first_data_block)) %
 518		      EXT2_BLOCKS_PER_GROUP(sb);
 519	/*
 520	 * Check to see if we are freeing blocks across a group
 521	 * boundary.
 522	 */
 523	if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
 524		overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
 525		count -= overflow;
 526	}
 527	brelse(bitmap_bh);
 528	bitmap_bh = read_block_bitmap(sb, block_group);
 529	if (!bitmap_bh)
 530		goto error_return;
 531
 532	desc = ext2_get_group_desc (sb, block_group, &bh2);
 533	if (!desc)
 534		goto error_return;
 535
 536	if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 537	    in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 538	    in_range (block, le32_to_cpu(desc->bg_inode_table),
 539		      sbi->s_itb_per_group) ||
 540	    in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 541		      sbi->s_itb_per_group)) {
 542		ext2_error (sb, "ext2_free_blocks",
 543			    "Freeing blocks in system zones - "
 544			    "Block = %lu, count = %lu",
 545			    block, count);
 546		goto error_return;
 547	}
 548
 549	for (i = 0, group_freed = 0; i < count; i++) {
 550		if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 551						bit + i, bitmap_bh->b_data)) {
 552			ext2_error(sb, __func__,
 553				"bit already cleared for block %lu", block + i);
 554		} else {
 555			group_freed++;
 556		}
 557	}
 558
 559	mark_buffer_dirty(bitmap_bh);
 560	if (sb->s_flags & MS_SYNCHRONOUS)
 561		sync_dirty_buffer(bitmap_bh);
 562
 563	group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
 564	freed += group_freed;
 565
 566	if (overflow) {
 567		block += count;
 568		count = overflow;
 569		goto do_more;
 570	}
 571error_return:
 572	brelse(bitmap_bh);
 573	release_blocks(sb, freed);
 574	dquot_free_block_nodirty(inode, freed);
 
 
 
 575}
 576
 577/**
 578 * bitmap_search_next_usable_block()
 579 * @start:		the starting block (group relative) of the search
 580 * @bh:			bufferhead contains the block group bitmap
 581 * @maxblocks:		the ending block (group relative) of the reservation
 582 *
 583 * The bitmap search --- search forward through the actual bitmap on disk until
 584 * we find a bit free.
 585 */
 586static ext2_grpblk_t
 587bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
 588					ext2_grpblk_t maxblocks)
 589{
 590	ext2_grpblk_t next;
 591
 592	next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
 593	if (next >= maxblocks)
 594		return -1;
 595	return next;
 596}
 597
 598/**
 599 * find_next_usable_block()
 600 * @start:		the starting block (group relative) to find next
 601 * 			allocatable block in bitmap.
 602 * @bh:			bufferhead contains the block group bitmap
 603 * @maxblocks:		the ending block (group relative) for the search
 604 *
 605 * Find an allocatable block in a bitmap.  We perform the "most
 606 * appropriate allocation" algorithm of looking for a free block near
 607 * the initial goal; then for a free byte somewhere in the bitmap;
 608 * then for any free bit in the bitmap.
 609 */
 610static ext2_grpblk_t
 611find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 612{
 613	ext2_grpblk_t here, next;
 614	char *p, *r;
 615
 616	if (start > 0) {
 617		/*
 618		 * The goal was occupied; search forward for a free 
 619		 * block within the next XX blocks.
 620		 *
 621		 * end_goal is more or less random, but it has to be
 622		 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
 623		 * next 64-bit boundary is simple..
 624		 */
 625		ext2_grpblk_t end_goal = (start + 63) & ~63;
 626		if (end_goal > maxblocks)
 627			end_goal = maxblocks;
 628		here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
 629		if (here < end_goal)
 630			return here;
 631		ext2_debug("Bit not found near goal\n");
 632	}
 633
 634	here = start;
 635	if (here < 0)
 636		here = 0;
 637
 638	p = ((char *)bh->b_data) + (here >> 3);
 639	r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 640	next = (r - ((char *)bh->b_data)) << 3;
 641
 642	if (next < maxblocks && next >= here)
 643		return next;
 644
 645	here = bitmap_search_next_usable_block(here, bh, maxblocks);
 646	return here;
 647}
 648
 649/**
 650 * ext2_try_to_allocate()
 651 * @sb:			superblock
 652 * @group:		given allocation block group
 653 * @bitmap_bh:		bufferhead holds the block bitmap
 654 * @grp_goal:		given target block within the group
 655 * @count:		target number of blocks to allocate
 656 * @my_rsv:		reservation window
 657 *
 658 * Attempt to allocate blocks within a give range. Set the range of allocation
 659 * first, then find the first free bit(s) from the bitmap (within the range),
 660 * and at last, allocate the blocks by claiming the found free bit as allocated.
 661 *
 662 * To set the range of this allocation:
 663 * 	if there is a reservation window, only try to allocate block(s)
 664 * 	from the file's own reservation window;
 665 * 	Otherwise, the allocation range starts from the give goal block,
 666 * 	ends at the block group's last block.
 667 *
 668 * If we failed to allocate the desired block then we may end up crossing to a
 669 * new bitmap.
 670 */
 671static int
 672ext2_try_to_allocate(struct super_block *sb, int group,
 673			struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
 674			unsigned long *count,
 675			struct ext2_reserve_window *my_rsv)
 676{
 677	ext2_fsblk_t group_first_block;
 678       	ext2_grpblk_t start, end;
 
 679	unsigned long num = 0;
 680
 
 
 681	/* we do allocation within the reservation window if we have a window */
 682	if (my_rsv) {
 683		group_first_block = ext2_group_first_block_no(sb, group);
 684		if (my_rsv->_rsv_start >= group_first_block)
 685			start = my_rsv->_rsv_start - group_first_block;
 686		else
 687			/* reservation window cross group boundary */
 688			start = 0;
 689		end = my_rsv->_rsv_end - group_first_block + 1;
 690		if (end > EXT2_BLOCKS_PER_GROUP(sb))
 691			/* reservation window crosses group boundary */
 692			end = EXT2_BLOCKS_PER_GROUP(sb);
 693		if ((start <= grp_goal) && (grp_goal < end))
 694			start = grp_goal;
 695		else
 696			grp_goal = -1;
 697	} else {
 698		if (grp_goal > 0)
 699			start = grp_goal;
 700		else
 701			start = 0;
 702		end = EXT2_BLOCKS_PER_GROUP(sb);
 703	}
 704
 705	BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
 706
 707repeat:
 708	if (grp_goal < 0) {
 709		grp_goal = find_next_usable_block(start, bitmap_bh, end);
 710		if (grp_goal < 0)
 711			goto fail_access;
 712		if (!my_rsv) {
 713			int i;
 714
 715			for (i = 0; i < 7 && grp_goal > start &&
 716					!ext2_test_bit(grp_goal - 1,
 717					     		bitmap_bh->b_data);
 718			     		i++, grp_goal--)
 719				;
 720		}
 721	}
 722	start = grp_goal;
 723
 724	if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group), grp_goal,
 725			       				bitmap_bh->b_data)) {
 726		/*
 727		 * The block was allocated by another thread, or it was
 728		 * allocated and then freed by another thread
 729		 */
 730		start++;
 731		grp_goal++;
 732		if (start >= end)
 733			goto fail_access;
 734		goto repeat;
 735	}
 736	num++;
 737	grp_goal++;
 738	while (num < *count && grp_goal < end
 739		&& !ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
 740					grp_goal, bitmap_bh->b_data)) {
 
 
 
 
 741		num++;
 742		grp_goal++;
 743	}
 
 
 
 
 744	*count = num;
 745	return grp_goal - num;
 746fail_access:
 747	*count = num;
 748	return -1;
 749}
 750
 751/**
 752 * 	find_next_reservable_window():
 753 *		find a reservable space within the given range.
 754 *		It does not allocate the reservation window for now:
 755 *		alloc_new_reservation() will do the work later.
 756 *
 757 * 	@search_head: the head of the searching list;
 758 *		This is not necessarily the list head of the whole filesystem
 759 *
 760 *		We have both head and start_block to assist the search
 761 *		for the reservable space. The list starts from head,
 762 *		but we will shift to the place where start_block is,
 763 *		then start from there, when looking for a reservable space.
 764 *
 765 * 	@size: the target new reservation window size
 766 *
 767 * 	@group_first_block: the first block we consider to start
 768 *			the real search from
 769 *
 770 * 	@last_block:
 771 *		the maximum block number that our goal reservable space
 772 *		could start from. This is normally the last block in this
 773 *		group. The search will end when we found the start of next
 774 *		possible reservable space is out of this boundary.
 775 *		This could handle the cross boundary reservation window
 776 *		request.
 777 *
 778 * 	basically we search from the given range, rather than the whole
 779 * 	reservation double linked list, (start_block, last_block)
 780 * 	to find a free region that is of my size and has not
 781 * 	been reserved.
 782 *
 
 
 783 */
 784static int find_next_reservable_window(
 785				struct ext2_reserve_window_node *search_head,
 786				struct ext2_reserve_window_node *my_rsv,
 787				struct super_block * sb,
 788				ext2_fsblk_t start_block,
 789				ext2_fsblk_t last_block)
 790{
 791	struct rb_node *next;
 792	struct ext2_reserve_window_node *rsv, *prev;
 793	ext2_fsblk_t cur;
 794	int size = my_rsv->rsv_goal_size;
 795
 796	/* TODO: make the start of the reservation window byte-aligned */
 797	/* cur = *start_block & ~7;*/
 798	cur = start_block;
 799	rsv = search_head;
 800	if (!rsv)
 801		return -1;
 802
 803	while (1) {
 804		if (cur <= rsv->rsv_end)
 805			cur = rsv->rsv_end + 1;
 806
 807		/* TODO?
 808		 * in the case we could not find a reservable space
 809		 * that is what is expected, during the re-search, we could
 810		 * remember what's the largest reservable space we could have
 811		 * and return that one.
 812		 *
 813		 * For now it will fail if we could not find the reservable
 814		 * space with expected-size (or more)...
 815		 */
 816		if (cur > last_block)
 817			return -1;		/* fail */
 818
 819		prev = rsv;
 820		next = rb_next(&rsv->rsv_node);
 821		rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
 822
 823		/*
 824		 * Reached the last reservation, we can just append to the
 825		 * previous one.
 826		 */
 827		if (!next)
 828			break;
 829
 830		if (cur + size <= rsv->rsv_start) {
 831			/*
 832			 * Found a reserveable space big enough.  We could
 833			 * have a reservation across the group boundary here
 834		 	 */
 835			break;
 836		}
 837	}
 838	/*
 839	 * we come here either :
 840	 * when we reach the end of the whole list,
 841	 * and there is empty reservable space after last entry in the list.
 842	 * append it to the end of the list.
 843	 *
 844	 * or we found one reservable space in the middle of the list,
 845	 * return the reservation window that we could append to.
 846	 * succeed.
 847	 */
 848
 849	if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
 850		rsv_window_remove(sb, my_rsv);
 851
 852	/*
 853	 * Let's book the whole available window for now.  We will check the
 854	 * disk bitmap later and then, if there are free blocks then we adjust
 855	 * the window size if it's larger than requested.
 856	 * Otherwise, we will remove this node from the tree next time
 857	 * call find_next_reservable_window.
 858	 */
 859	my_rsv->rsv_start = cur;
 860	my_rsv->rsv_end = cur + size - 1;
 861	my_rsv->rsv_alloc_hit = 0;
 862
 863	if (prev != my_rsv)
 864		ext2_rsv_window_add(sb, my_rsv);
 865
 866	return 0;
 867}
 868
 869/**
 870 * 	alloc_new_reservation()--allocate a new reservation window
 871 *
 872 *		To make a new reservation, we search part of the filesystem
 873 *		reservation list (the list that inside the group). We try to
 874 *		allocate a new reservation window near the allocation goal,
 875 *		or the beginning of the group, if there is no goal.
 876 *
 877 *		We first find a reservable space after the goal, then from
 878 *		there, we check the bitmap for the first free block after
 879 *		it. If there is no free block until the end of group, then the
 880 *		whole group is full, we failed. Otherwise, check if the free
 881 *		block is inside the expected reservable space, if so, we
 882 *		succeed.
 883 *		If the first free block is outside the reservable space, then
 884 *		start from the first free block, we search for next available
 885 *		space, and go on.
 886 *
 887 *	on succeed, a new reservation will be found and inserted into the list
 888 *	It contains at least one free block, and it does not overlap with other
 889 *	reservation windows.
 890 *
 891 *	failed: we failed to find a reservation window in this group
 892 *
 893 *	@rsv: the reservation
 894 *
 895 *	@grp_goal: The goal (group-relative).  It is where the search for a
 896 *		free reservable space should start from.
 897 *		if we have a goal(goal >0 ), then start from there,
 898 *		no goal(goal = -1), we start from the first block
 899 *		of the group.
 900 *
 901 *	@sb: the super block
 902 *	@group: the group we are trying to allocate in
 903 *	@bitmap_bh: the block group block bitmap
 904 *
 
 
 905 */
 906static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
 907		ext2_grpblk_t grp_goal, struct super_block *sb,
 908		unsigned int group, struct buffer_head *bitmap_bh)
 909{
 910	struct ext2_reserve_window_node *search_head;
 911	ext2_fsblk_t group_first_block, group_end_block, start_block;
 912	ext2_grpblk_t first_free_block;
 913	struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
 914	unsigned long size;
 915	int ret;
 916	spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
 917
 918	group_first_block = ext2_group_first_block_no(sb, group);
 919	group_end_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
 920
 921	if (grp_goal < 0)
 922		start_block = group_first_block;
 923	else
 924		start_block = grp_goal + group_first_block;
 925
 926	size = my_rsv->rsv_goal_size;
 927
 928	if (!rsv_is_empty(&my_rsv->rsv_window)) {
 929		/*
 930		 * if the old reservation is cross group boundary
 931		 * and if the goal is inside the old reservation window,
 932		 * we will come here when we just failed to allocate from
 933		 * the first part of the window. We still have another part
 934		 * that belongs to the next group. In this case, there is no
 935		 * point to discard our window and try to allocate a new one
 936		 * in this group(which will fail). we should
 937		 * keep the reservation window, just simply move on.
 938		 *
 939		 * Maybe we could shift the start block of the reservation
 940		 * window to the first block of next group.
 941		 */
 942
 943		if ((my_rsv->rsv_start <= group_end_block) &&
 944				(my_rsv->rsv_end > group_end_block) &&
 945				(start_block >= my_rsv->rsv_start))
 946			return -1;
 947
 948		if ((my_rsv->rsv_alloc_hit >
 949		     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
 950			/*
 951			 * if the previously allocation hit ratio is
 952			 * greater than 1/2, then we double the size of
 953			 * the reservation window the next time,
 954			 * otherwise we keep the same size window
 955			 */
 956			size = size * 2;
 957			if (size > EXT2_MAX_RESERVE_BLOCKS)
 958				size = EXT2_MAX_RESERVE_BLOCKS;
 959			my_rsv->rsv_goal_size= size;
 960		}
 961	}
 962
 963	spin_lock(rsv_lock);
 964	/*
 965	 * shift the search start to the window near the goal block
 966	 */
 967	search_head = search_reserve_window(fs_rsv_root, start_block);
 968
 969	/*
 970	 * find_next_reservable_window() simply finds a reservable window
 971	 * inside the given range(start_block, group_end_block).
 972	 *
 973	 * To make sure the reservation window has a free bit inside it, we
 974	 * need to check the bitmap after we found a reservable window.
 975	 */
 976retry:
 977	ret = find_next_reservable_window(search_head, my_rsv, sb,
 978						start_block, group_end_block);
 979
 980	if (ret == -1) {
 981		if (!rsv_is_empty(&my_rsv->rsv_window))
 982			rsv_window_remove(sb, my_rsv);
 983		spin_unlock(rsv_lock);
 984		return -1;
 985	}
 986
 987	/*
 988	 * On success, find_next_reservable_window() returns the
 989	 * reservation window where there is a reservable space after it.
 990	 * Before we reserve this reservable space, we need
 991	 * to make sure there is at least a free block inside this region.
 992	 *
 993	 * Search the first free bit on the block bitmap.  Search starts from
 994	 * the start block of the reservable space we just found.
 995	 */
 996	spin_unlock(rsv_lock);
 997	first_free_block = bitmap_search_next_usable_block(
 998			my_rsv->rsv_start - group_first_block,
 999			bitmap_bh, group_end_block - group_first_block + 1);
1000
1001	if (first_free_block < 0) {
1002		/*
1003		 * no free block left on the bitmap, no point
1004		 * to reserve the space. return failed.
1005		 */
1006		spin_lock(rsv_lock);
1007		if (!rsv_is_empty(&my_rsv->rsv_window))
1008			rsv_window_remove(sb, my_rsv);
1009		spin_unlock(rsv_lock);
1010		return -1;		/* failed */
1011	}
1012
1013	start_block = first_free_block + group_first_block;
1014	/*
1015	 * check if the first free block is within the
1016	 * free space we just reserved
1017	 */
1018	if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1019		return 0;		/* success */
1020	/*
1021	 * if the first free bit we found is out of the reservable space
1022	 * continue search for next reservable space,
1023	 * start from where the free block is,
1024	 * we also shift the list head to where we stopped last time
1025	 */
1026	search_head = my_rsv;
1027	spin_lock(rsv_lock);
1028	goto retry;
1029}
1030
1031/**
1032 * try_to_extend_reservation()
1033 * @my_rsv:		given reservation window
1034 * @sb:			super block
1035 * @size:		the delta to extend
1036 *
1037 * Attempt to expand the reservation window large enough to have
1038 * required number of free blocks
1039 *
1040 * Since ext2_try_to_allocate() will always allocate blocks within
1041 * the reservation window range, if the window size is too small,
1042 * multiple blocks allocation has to stop at the end of the reservation
1043 * window. To make this more efficient, given the total number of
1044 * blocks needed and the current size of the window, we try to
1045 * expand the reservation window size if necessary on a best-effort
1046 * basis before ext2_new_blocks() tries to allocate blocks.
1047 */
1048static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
1049			struct super_block *sb, int size)
1050{
1051	struct ext2_reserve_window_node *next_rsv;
1052	struct rb_node *next;
1053	spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
1054
1055	if (!spin_trylock(rsv_lock))
1056		return;
1057
1058	next = rb_next(&my_rsv->rsv_node);
1059
1060	if (!next)
1061		my_rsv->rsv_end += size;
1062	else {
1063		next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
1064
1065		if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1066			my_rsv->rsv_end += size;
1067		else
1068			my_rsv->rsv_end = next_rsv->rsv_start - 1;
1069	}
1070	spin_unlock(rsv_lock);
1071}
1072
1073/**
1074 * ext2_try_to_allocate_with_rsv()
1075 * @sb:			superblock
1076 * @group:		given allocation block group
1077 * @bitmap_bh:		bufferhead holds the block bitmap
1078 * @grp_goal:		given target block within the group
1079 * @count:		target number of blocks to allocate
1080 * @my_rsv:		reservation window
1081 *
1082 * This is the main function used to allocate a new block and its reservation
1083 * window.
1084 *
1085 * Each time when a new block allocation is need, first try to allocate from
1086 * its own reservation.  If it does not have a reservation window, instead of
1087 * looking for a free bit on bitmap first, then look up the reservation list to
1088 * see if it is inside somebody else's reservation window, we try to allocate a
1089 * reservation window for it starting from the goal first. Then do the block
1090 * allocation within the reservation window.
1091 *
1092 * This will avoid keeping on searching the reservation list again and
1093 * again when somebody is looking for a free block (without
1094 * reservation), and there are lots of free blocks, but they are all
1095 * being reserved.
1096 *
1097 * We use a red-black tree for the per-filesystem reservation list.
1098 */
1099static ext2_grpblk_t
1100ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
1101			struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
1102			struct ext2_reserve_window_node * my_rsv,
1103			unsigned long *count)
1104{
1105	ext2_fsblk_t group_first_block, group_last_block;
1106	ext2_grpblk_t ret = 0;
1107	unsigned long num = *count;
1108
1109	/*
1110	 * we don't deal with reservation when
1111	 * filesystem is mounted without reservation
1112	 * or the file is not a regular file
1113	 * or last attempt to allocate a block with reservation turned on failed
1114	 */
1115	if (my_rsv == NULL) {
1116		return ext2_try_to_allocate(sb, group, bitmap_bh,
1117						grp_goal, count, NULL);
1118	}
1119	/*
1120	 * grp_goal is a group relative block number (if there is a goal)
1121	 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
1122	 * first block is a filesystem wide block number
1123	 * first block is the block number of the first block in this group
1124	 */
1125	group_first_block = ext2_group_first_block_no(sb, group);
1126	group_last_block = group_first_block + (EXT2_BLOCKS_PER_GROUP(sb) - 1);
1127
1128	/*
1129	 * Basically we will allocate a new block from inode's reservation
1130	 * window.
1131	 *
1132	 * We need to allocate a new reservation window, if:
1133	 * a) inode does not have a reservation window; or
1134	 * b) last attempt to allocate a block from existing reservation
1135	 *    failed; or
1136	 * c) we come here with a goal and with a reservation window
1137	 *
1138	 * We do not need to allocate a new reservation window if we come here
1139	 * at the beginning with a goal and the goal is inside the window, or
1140	 * we don't have a goal but already have a reservation window.
1141	 * then we could go to allocate from the reservation window directly.
1142	 */
1143	while (1) {
1144		if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1145			!goal_in_my_reservation(&my_rsv->rsv_window,
1146						grp_goal, group, sb)) {
1147			if (my_rsv->rsv_goal_size < *count)
1148				my_rsv->rsv_goal_size = *count;
1149			ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1150							group, bitmap_bh);
1151			if (ret < 0)
1152				break;			/* failed */
1153
1154			if (!goal_in_my_reservation(&my_rsv->rsv_window,
1155							grp_goal, group, sb))
1156				grp_goal = -1;
1157		} else if (grp_goal >= 0) {
1158			int curr = my_rsv->rsv_end -
1159					(grp_goal + group_first_block) + 1;
1160
1161			if (curr < *count)
1162				try_to_extend_reservation(my_rsv, sb,
1163							*count - curr);
1164		}
1165
1166		if ((my_rsv->rsv_start > group_last_block) ||
1167				(my_rsv->rsv_end < group_first_block)) {
 
 
 
 
 
1168			rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
1169			BUG();
1170		}
1171		ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
1172					   &num, &my_rsv->rsv_window);
1173		if (ret >= 0) {
1174			my_rsv->rsv_alloc_hit += num;
1175			*count = num;
1176			break;				/* succeed */
1177		}
1178		num = *count;
1179	}
1180	return ret;
1181}
1182
1183/**
1184 * ext2_has_free_blocks()
1185 * @sbi:		in-core super block structure.
1186 *
1187 * Check if filesystem has at least 1 free block available for allocation.
1188 */
1189static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
1190{
1191	ext2_fsblk_t free_blocks, root_blocks;
1192
1193	free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1194	root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1195	if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1196		sbi->s_resuid != current_fsuid() &&
1197		(sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
 
1198		return 0;
1199	}
1200	return 1;
1201}
1202
1203/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1204 * ext2_new_blocks() -- core block(s) allocation function
1205 * @inode:		file inode
1206 * @goal:		given target block(filesystem wide)
1207 * @count:		target number of blocks to allocate
1208 * @errp:		error code
 
1209 *
1210 * ext2_new_blocks uses a goal block to assist allocation.  If the goal is
1211 * free, or there is a free block within 32 blocks of the goal, that block
1212 * is allocated.  Otherwise a forward search is made for a free block; within 
1213 * each block group the search first looks for an entire free byte in the block
1214 * bitmap, and then for any free bit if that fails.
1215 * This function also updates quota and i_blocks field.
1216 */
1217ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
1218		    unsigned long *count, int *errp)
1219{
1220	struct buffer_head *bitmap_bh = NULL;
1221	struct buffer_head *gdp_bh;
1222	int group_no;
1223	int goal_group;
1224	ext2_grpblk_t grp_target_blk;	/* blockgroup relative goal block */
1225	ext2_grpblk_t grp_alloc_blk;	/* blockgroup-relative allocated block*/
1226	ext2_fsblk_t ret_block;		/* filesyetem-wide allocated block */
1227	int bgi;			/* blockgroup iteration index */
1228	int performed_allocation = 0;
1229	ext2_grpblk_t free_blocks;	/* number of free blocks in a group */
1230	struct super_block *sb;
1231	struct ext2_group_desc *gdp;
1232	struct ext2_super_block *es;
1233	struct ext2_sb_info *sbi;
1234	struct ext2_reserve_window_node *my_rsv = NULL;
1235	struct ext2_block_alloc_info *block_i;
1236	unsigned short windowsz = 0;
1237	unsigned long ngroups;
1238	unsigned long num = *count;
1239	int ret;
1240
1241	*errp = -ENOSPC;
1242	sb = inode->i_sb;
1243	if (!sb) {
1244		printk("ext2_new_blocks: nonexistent device");
1245		return 0;
1246	}
1247
1248	/*
1249	 * Check quota for allocation of this block.
1250	 */
1251	ret = dquot_alloc_block(inode, num);
1252	if (ret) {
1253		*errp = ret;
1254		return 0;
1255	}
1256
1257	sbi = EXT2_SB(sb);
1258	es = EXT2_SB(sb)->s_es;
1259	ext2_debug("goal=%lu.\n", goal);
1260	/*
1261	 * Allocate a block from reservation only when
1262	 * filesystem is mounted with reservation(default,-o reservation), and
1263	 * it's a regular file, and
1264	 * the desired window size is greater than 0 (One could use ioctl
1265	 * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
1266	 * reservation on that particular file)
1267	 */
1268	block_i = EXT2_I(inode)->i_block_alloc_info;
1269	if (block_i) {
1270		windowsz = block_i->rsv_window_node.rsv_goal_size;
1271		if (windowsz > 0)
1272			my_rsv = &block_i->rsv_window_node;
1273	}
1274
1275	if (!ext2_has_free_blocks(sbi)) {
1276		*errp = -ENOSPC;
1277		goto out;
1278	}
1279
1280	/*
1281	 * First, test whether the goal block is free.
1282	 */
1283	if (goal < le32_to_cpu(es->s_first_data_block) ||
1284	    goal >= le32_to_cpu(es->s_blocks_count))
1285		goal = le32_to_cpu(es->s_first_data_block);
1286	group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1287			EXT2_BLOCKS_PER_GROUP(sb);
1288	goal_group = group_no;
1289retry_alloc:
1290	gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1291	if (!gdp)
1292		goto io_error;
1293
1294	free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1295	/*
1296	 * if there is not enough free blocks to make a new resevation
1297	 * turn off reservation for this allocation
1298	 */
1299	if (my_rsv && (free_blocks < windowsz)
1300		&& (free_blocks > 0)
1301		&& (rsv_is_empty(&my_rsv->rsv_window)))
1302		my_rsv = NULL;
1303
1304	if (free_blocks > 0) {
1305		grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1306				EXT2_BLOCKS_PER_GROUP(sb));
 
 
 
 
 
 
 
1307		bitmap_bh = read_block_bitmap(sb, group_no);
1308		if (!bitmap_bh)
1309			goto io_error;
1310		grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1311					bitmap_bh, grp_target_blk,
1312					my_rsv, &num);
1313		if (grp_alloc_blk >= 0)
1314			goto allocated;
1315	}
1316
1317	ngroups = EXT2_SB(sb)->s_groups_count;
1318	smp_rmb();
1319
1320	/*
1321	 * Now search the rest of the groups.  We assume that
1322	 * group_no and gdp correctly point to the last group visited.
1323	 */
1324	for (bgi = 0; bgi < ngroups; bgi++) {
1325		group_no++;
1326		if (group_no >= ngroups)
1327			group_no = 0;
1328		gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
1329		if (!gdp)
1330			goto io_error;
1331
1332		free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1333		/*
1334		 * skip this group (and avoid loading bitmap) if there
1335		 * are no free blocks
1336		 */
1337		if (!free_blocks)
1338			continue;
1339		/*
1340		 * skip this group if the number of
1341		 * free blocks is less than half of the reservation
1342		 * window size.
1343		 */
1344		if (my_rsv && (free_blocks <= (windowsz/2)))
1345			continue;
1346
1347		brelse(bitmap_bh);
1348		bitmap_bh = read_block_bitmap(sb, group_no);
1349		if (!bitmap_bh)
1350			goto io_error;
1351		/*
1352		 * try to allocate block(s) from this group, without a goal(-1).
1353		 */
1354		grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
1355					bitmap_bh, -1, my_rsv, &num);
1356		if (grp_alloc_blk >= 0)
1357			goto allocated;
1358	}
1359	/*
1360	 * We may end up a bogus earlier ENOSPC error due to
1361	 * filesystem is "full" of reservations, but
1362	 * there maybe indeed free blocks available on disk
1363	 * In this case, we just forget about the reservations
1364	 * just do block allocation as without reservations.
1365	 */
1366	if (my_rsv) {
1367		my_rsv = NULL;
1368		windowsz = 0;
1369		group_no = goal_group;
1370		goto retry_alloc;
1371	}
1372	/* No space left on the device */
1373	*errp = -ENOSPC;
1374	goto out;
1375
1376allocated:
1377
1378	ext2_debug("using block group %d(%d)\n",
1379			group_no, gdp->bg_free_blocks_count);
1380
1381	ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
1382
1383	if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1384	    in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1385	    in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1386		      EXT2_SB(sb)->s_itb_per_group) ||
1387	    in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1388		      EXT2_SB(sb)->s_itb_per_group)) {
1389		ext2_error(sb, "ext2_new_blocks",
1390			    "Allocating block in system zone - "
1391			    "blocks from "E2FSBLK", length %lu",
1392			    ret_block, num);
1393		/*
1394		 * ext2_try_to_allocate marked the blocks we allocated as in
1395		 * use.  So we may want to selectively mark some of the blocks
1396		 * as free
1397		 */
 
1398		goto retry_alloc;
1399	}
1400
1401	performed_allocation = 1;
1402
1403	if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1404		ext2_error(sb, "ext2_new_blocks",
1405			    "block("E2FSBLK") >= blocks count(%d) - "
1406			    "block_group = %d, es == %p ", ret_block,
1407			le32_to_cpu(es->s_blocks_count), group_no, es);
1408		goto out;
1409	}
1410
1411	group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
1412	percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1413
1414	mark_buffer_dirty(bitmap_bh);
1415	if (sb->s_flags & MS_SYNCHRONOUS)
1416		sync_dirty_buffer(bitmap_bh);
1417
1418	*errp = 0;
1419	brelse(bitmap_bh);
1420	dquot_free_block_nodirty(inode, *count-num);
1421	mark_inode_dirty(inode);
1422	*count = num;
 
 
1423	return ret_block;
1424
1425io_error:
1426	*errp = -EIO;
1427out:
1428	/*
1429	 * Undo the block allocation
1430	 */
1431	if (!performed_allocation) {
1432		dquot_free_block_nodirty(inode, *count);
1433		mark_inode_dirty(inode);
1434	}
1435	brelse(bitmap_bh);
1436	return 0;
1437}
1438
1439ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
1440{
1441	unsigned long count = 1;
1442
1443	return ext2_new_blocks(inode, goal, &count, errp);
1444}
1445
1446#ifdef EXT2FS_DEBUG
1447
1448static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
1449
1450unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
1451{
1452	unsigned int i;
1453	unsigned long sum = 0;
1454
1455	if (!map)
1456		return (0);
1457	for (i = 0; i < numchars; i++)
1458		sum += nibblemap[map->b_data[i] & 0xf] +
1459			nibblemap[(map->b_data[i] >> 4) & 0xf];
1460	return (sum);
1461}
1462
1463#endif  /*  EXT2FS_DEBUG  */
1464
1465unsigned long ext2_count_free_blocks (struct super_block * sb)
1466{
1467	struct ext2_group_desc * desc;
1468	unsigned long desc_count = 0;
1469	int i;
1470#ifdef EXT2FS_DEBUG
1471	unsigned long bitmap_count, x;
1472	struct ext2_super_block *es;
1473
1474	es = EXT2_SB(sb)->s_es;
1475	desc_count = 0;
1476	bitmap_count = 0;
1477	desc = NULL;
1478	for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1479		struct buffer_head *bitmap_bh;
1480		desc = ext2_get_group_desc (sb, i, NULL);
1481		if (!desc)
1482			continue;
1483		desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1484		bitmap_bh = read_block_bitmap(sb, i);
1485		if (!bitmap_bh)
1486			continue;
1487		
1488		x = ext2_count_free(bitmap_bh, sb->s_blocksize);
1489		printk ("group %d: stored = %d, counted = %lu\n",
1490			i, le16_to_cpu(desc->bg_free_blocks_count), x);
1491		bitmap_count += x;
1492		brelse(bitmap_bh);
1493	}
1494	printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
1495		(long)le32_to_cpu(es->s_free_blocks_count),
1496		desc_count, bitmap_count);
1497	return bitmap_count;
1498#else
1499        for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
1500                desc = ext2_get_group_desc (sb, i, NULL);
1501                if (!desc)
1502                        continue;
1503                desc_count += le16_to_cpu(desc->bg_free_blocks_count);
1504	}
1505	return desc_count;
1506#endif
1507}
1508
1509static inline int test_root(int a, int b)
1510{
1511	int num = b;
1512
1513	while (a > num)
1514		num *= b;
1515	return num == a;
1516}
1517
1518static int ext2_group_sparse(int group)
1519{
1520	if (group <= 1)
1521		return 1;
1522	return (test_root(group, 3) || test_root(group, 5) ||
1523		test_root(group, 7));
1524}
1525
1526/**
1527 *	ext2_bg_has_super - number of blocks used by the superblock in group
1528 *	@sb: superblock for filesystem
1529 *	@group: group number to check
1530 *
1531 *	Return the number of blocks used by the superblock (primary or backup)
1532 *	in this group.  Currently this will be only 0 or 1.
1533 */
1534int ext2_bg_has_super(struct super_block *sb, int group)
1535{
1536	if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1537	    !ext2_group_sparse(group))
1538		return 0;
1539	return 1;
1540}
1541
1542/**
1543 *	ext2_bg_num_gdb - number of blocks used by the group table in group
1544 *	@sb: superblock for filesystem
1545 *	@group: group number to check
1546 *
1547 *	Return the number of blocks used by the group descriptor table
1548 *	(primary or backup) in this group.  In the future there may be a
1549 *	different number of descriptor blocks in each group.
1550 */
1551unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
1552{
1553	return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
1554}
1555