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