cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
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balloc.c (45689B)


      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 *  linux/fs/ext2/balloc.c
      4 *
      5 * Copyright (C) 1992, 1993, 1994, 1995
      6 * Remy Card (card@masi.ibp.fr)
      7 * Laboratoire MASI - Institut Blaise Pascal
      8 * Universite Pierre et Marie Curie (Paris VI)
      9 *
     10 *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
     11 *  Big-endian to little-endian byte-swapping/bitmaps by
     12 *        David S. Miller (davem@caip.rutgers.edu), 1995
     13 */
     14
     15#include "ext2.h"
     16#include <linux/quotaops.h>
     17#include <linux/slab.h>
     18#include <linux/sched.h>
     19#include <linux/cred.h>
     20#include <linux/buffer_head.h>
     21#include <linux/capability.h>
     22
     23/*
     24 * balloc.c contains the blocks allocation and deallocation routines
     25 */
     26
     27/*
     28 * The free blocks are managed by bitmaps.  A file system contains several
     29 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
     30 * block for inodes, N blocks for the inode table and data blocks.
     31 *
     32 * The file system contains group descriptors which are located after the
     33 * super block.  Each descriptor contains the number of the bitmap block and
     34 * the free blocks count in the block.  The descriptors are loaded in memory
     35 * when a file system is mounted (see ext2_fill_super).
     36 */
     37
     38
     39#define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)
     40
     41struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
     42					     unsigned int block_group,
     43					     struct buffer_head ** bh)
     44{
     45	unsigned long group_desc;
     46	unsigned long offset;
     47	struct ext2_group_desc * desc;
     48	struct ext2_sb_info *sbi = EXT2_SB(sb);
     49
     50	if (block_group >= sbi->s_groups_count) {
     51		WARN(1, "block_group >= groups_count - "
     52		     "block_group = %d, groups_count = %lu",
     53		     block_group, sbi->s_groups_count);
     54
     55		return NULL;
     56	}
     57
     58	group_desc = block_group >> EXT2_DESC_PER_BLOCK_BITS(sb);
     59	offset = block_group & (EXT2_DESC_PER_BLOCK(sb) - 1);
     60	if (!sbi->s_group_desc[group_desc]) {
     61		WARN(1, "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 * @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 = ext2_group_last_block_no(sb, group);
    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 * @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 (!ext2_data_block_valid(sbi, block, count)) {
    492		ext2_error (sb, "ext2_free_blocks",
    493			    "Freeing blocks not in datazone - "
    494			    "block = %lu, count = %lu", block, count);
    495		goto error_return;
    496	}
    497
    498	ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
    499
    500do_more:
    501	overflow = 0;
    502	block_group = (block - le32_to_cpu(es->s_first_data_block)) /
    503		      EXT2_BLOCKS_PER_GROUP(sb);
    504	bit = (block - le32_to_cpu(es->s_first_data_block)) %
    505		      EXT2_BLOCKS_PER_GROUP(sb);
    506	/*
    507	 * Check to see if we are freeing blocks across a group
    508	 * boundary.
    509	 */
    510	if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
    511		overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
    512		count -= overflow;
    513	}
    514	brelse(bitmap_bh);
    515	bitmap_bh = read_block_bitmap(sb, block_group);
    516	if (!bitmap_bh)
    517		goto error_return;
    518
    519	desc = ext2_get_group_desc (sb, block_group, &bh2);
    520	if (!desc)
    521		goto error_return;
    522
    523	if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
    524	    in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
    525	    in_range (block, le32_to_cpu(desc->bg_inode_table),
    526		      sbi->s_itb_per_group) ||
    527	    in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
    528		      sbi->s_itb_per_group)) {
    529		ext2_error (sb, "ext2_free_blocks",
    530			    "Freeing blocks in system zones - "
    531			    "Block = %lu, count = %lu",
    532			    block, count);
    533		goto error_return;
    534	}
    535
    536	for (i = 0, group_freed = 0; i < count; i++) {
    537		if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
    538						bit + i, bitmap_bh->b_data)) {
    539			ext2_error(sb, __func__,
    540				"bit already cleared for block %lu", block + i);
    541		} else {
    542			group_freed++;
    543		}
    544	}
    545
    546	mark_buffer_dirty(bitmap_bh);
    547	if (sb->s_flags & SB_SYNCHRONOUS)
    548		sync_dirty_buffer(bitmap_bh);
    549
    550	group_adjust_blocks(sb, block_group, desc, bh2, group_freed);
    551	freed += group_freed;
    552
    553	if (overflow) {
    554		block += count;
    555		count = overflow;
    556		goto do_more;
    557	}
    558error_return:
    559	brelse(bitmap_bh);
    560	if (freed) {
    561		percpu_counter_add(&sbi->s_freeblocks_counter, freed);
    562		dquot_free_block_nodirty(inode, freed);
    563		mark_inode_dirty(inode);
    564	}
    565}
    566
    567/**
    568 * bitmap_search_next_usable_block()
    569 * @start:		the starting block (group relative) of the search
    570 * @bh:			bufferhead contains the block group bitmap
    571 * @maxblocks:		the ending block (group relative) of the reservation
    572 *
    573 * The bitmap search --- search forward through the actual bitmap on disk until
    574 * we find a bit free.
    575 */
    576static ext2_grpblk_t
    577bitmap_search_next_usable_block(ext2_grpblk_t start, struct buffer_head *bh,
    578					ext2_grpblk_t maxblocks)
    579{
    580	ext2_grpblk_t next;
    581
    582	next = ext2_find_next_zero_bit(bh->b_data, maxblocks, start);
    583	if (next >= maxblocks)
    584		return -1;
    585	return next;
    586}
    587
    588/**
    589 * find_next_usable_block()
    590 * @start:		the starting block (group relative) to find next
    591 * 			allocatable block in bitmap.
    592 * @bh:			bufferhead contains the block group bitmap
    593 * @maxblocks:		the ending block (group relative) for the search
    594 *
    595 * Find an allocatable block in a bitmap.  We perform the "most
    596 * appropriate allocation" algorithm of looking for a free block near
    597 * the initial goal; then for a free byte somewhere in the bitmap;
    598 * then for any free bit in the bitmap.
    599 */
    600static ext2_grpblk_t
    601find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
    602{
    603	ext2_grpblk_t here, next;
    604	char *p, *r;
    605
    606	if (start > 0) {
    607		/*
    608		 * The goal was occupied; search forward for a free 
    609		 * block within the next XX blocks.
    610		 *
    611		 * end_goal is more or less random, but it has to be
    612		 * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
    613		 * next 64-bit boundary is simple..
    614		 */
    615		ext2_grpblk_t end_goal = (start + 63) & ~63;
    616		if (end_goal > maxblocks)
    617			end_goal = maxblocks;
    618		here = ext2_find_next_zero_bit(bh->b_data, end_goal, start);
    619		if (here < end_goal)
    620			return here;
    621		ext2_debug("Bit not found near goal\n");
    622	}
    623
    624	here = start;
    625	if (here < 0)
    626		here = 0;
    627
    628	p = ((char *)bh->b_data) + (here >> 3);
    629	r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
    630	next = (r - ((char *)bh->b_data)) << 3;
    631
    632	if (next < maxblocks && next >= here)
    633		return next;
    634
    635	here = bitmap_search_next_usable_block(here, bh, maxblocks);
    636	return here;
    637}
    638
    639/**
    640 * ext2_try_to_allocate()
    641 * @sb:			superblock
    642 * @group:		given allocation block group
    643 * @bitmap_bh:		bufferhead holds the block bitmap
    644 * @grp_goal:		given target block within the group
    645 * @count:		target number of blocks to allocate
    646 * @my_rsv:		reservation window
    647 *
    648 * Attempt to allocate blocks within a give range. Set the range of allocation
    649 * first, then find the first free bit(s) from the bitmap (within the range),
    650 * and at last, allocate the blocks by claiming the found free bit as allocated.
    651 *
    652 * To set the range of this allocation:
    653 * 	if there is a reservation window, only try to allocate block(s)
    654 * 	from the file's own reservation window;
    655 * 	Otherwise, the allocation range starts from the give goal block,
    656 * 	ends at the block group's last block.
    657 *
    658 * If we failed to allocate the desired block then we may end up crossing to a
    659 * new bitmap.
    660 */
    661static int
    662ext2_try_to_allocate(struct super_block *sb, int group,
    663			struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
    664			unsigned long *count,
    665			struct ext2_reserve_window *my_rsv)
    666{
    667	ext2_fsblk_t group_first_block = ext2_group_first_block_no(sb, group);
    668	ext2_fsblk_t group_last_block = ext2_group_last_block_no(sb, group);
    669       	ext2_grpblk_t start, end;
    670	unsigned long num = 0;
    671
    672	start = 0;
    673	end = group_last_block - group_first_block + 1;
    674	/* we do allocation within the reservation window if we have a window */
    675	if (my_rsv) {
    676		if (my_rsv->_rsv_start >= group_first_block)
    677			start = my_rsv->_rsv_start - group_first_block;
    678		if (my_rsv->_rsv_end < group_last_block)
    679			end = my_rsv->_rsv_end - group_first_block + 1;
    680		if (grp_goal < start || grp_goal >= end)
    681			grp_goal = -1;
    682	}
    683	BUG_ON(start > EXT2_BLOCKS_PER_GROUP(sb));
    684
    685	if (grp_goal < 0) {
    686		grp_goal = find_next_usable_block(start, bitmap_bh, end);
    687		if (grp_goal < 0)
    688			goto fail_access;
    689		if (!my_rsv) {
    690			int i;
    691
    692			for (i = 0; i < 7 && grp_goal > start &&
    693					!ext2_test_bit(grp_goal - 1,
    694					     		bitmap_bh->b_data);
    695			     		i++, grp_goal--)
    696				;
    697		}
    698	}
    699
    700	for (; num < *count && grp_goal < end; grp_goal++) {
    701		if (ext2_set_bit_atomic(sb_bgl_lock(EXT2_SB(sb), group),
    702					grp_goal, bitmap_bh->b_data)) {
    703			if (num == 0)
    704				continue;
    705			break;
    706		}
    707		num++;
    708	}
    709
    710	if (num == 0)
    711		goto fail_access;
    712
    713	*count = num;
    714	return grp_goal - num;
    715fail_access:
    716	return -1;
    717}
    718
    719/**
    720 * 	find_next_reservable_window():
    721 *		find a reservable space within the given range.
    722 *		It does not allocate the reservation window for now:
    723 *		alloc_new_reservation() will do the work later.
    724 *
    725 * 	@search_head: the head of the searching list;
    726 *		This is not necessarily the list head of the whole filesystem
    727 *
    728 *		We have both head and start_block to assist the search
    729 *		for the reservable space. The list starts from head,
    730 *		but we will shift to the place where start_block is,
    731 *		then start from there, when looking for a reservable space.
    732 *
    733 *	@sb: the super block.
    734 *
    735 * 	@start_block: the first block we consider to start the real search from
    736 *
    737 * 	@last_block:
    738 *		the maximum block number that our goal reservable space
    739 *		could start from. This is normally the last block in this
    740 *		group. The search will end when we found the start of next
    741 *		possible reservable space is out of this boundary.
    742 *		This could handle the cross boundary reservation window
    743 *		request.
    744 *
    745 * 	basically we search from the given range, rather than the whole
    746 * 	reservation double linked list, (start_block, last_block)
    747 * 	to find a free region that is of my size and has not
    748 * 	been reserved.
    749 *
    750 */
    751static int find_next_reservable_window(
    752				struct ext2_reserve_window_node *search_head,
    753				struct ext2_reserve_window_node *my_rsv,
    754				struct super_block * sb,
    755				ext2_fsblk_t start_block,
    756				ext2_fsblk_t last_block)
    757{
    758	struct rb_node *next;
    759	struct ext2_reserve_window_node *rsv, *prev;
    760	ext2_fsblk_t cur;
    761	int size = my_rsv->rsv_goal_size;
    762
    763	/* TODO: make the start of the reservation window byte-aligned */
    764	/* cur = *start_block & ~7;*/
    765	cur = start_block;
    766	rsv = search_head;
    767	if (!rsv)
    768		return -1;
    769
    770	while (1) {
    771		if (cur <= rsv->rsv_end)
    772			cur = rsv->rsv_end + 1;
    773
    774		/* TODO?
    775		 * in the case we could not find a reservable space
    776		 * that is what is expected, during the re-search, we could
    777		 * remember what's the largest reservable space we could have
    778		 * and return that one.
    779		 *
    780		 * For now it will fail if we could not find the reservable
    781		 * space with expected-size (or more)...
    782		 */
    783		if (cur > last_block)
    784			return -1;		/* fail */
    785
    786		prev = rsv;
    787		next = rb_next(&rsv->rsv_node);
    788		rsv = rb_entry(next,struct ext2_reserve_window_node,rsv_node);
    789
    790		/*
    791		 * Reached the last reservation, we can just append to the
    792		 * previous one.
    793		 */
    794		if (!next)
    795			break;
    796
    797		if (cur + size <= rsv->rsv_start) {
    798			/*
    799			 * Found a reserveable space big enough.  We could
    800			 * have a reservation across the group boundary here
    801		 	 */
    802			break;
    803		}
    804	}
    805	/*
    806	 * we come here either :
    807	 * when we reach the end of the whole list,
    808	 * and there is empty reservable space after last entry in the list.
    809	 * append it to the end of the list.
    810	 *
    811	 * or we found one reservable space in the middle of the list,
    812	 * return the reservation window that we could append to.
    813	 * succeed.
    814	 */
    815
    816	if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
    817		rsv_window_remove(sb, my_rsv);
    818
    819	/*
    820	 * Let's book the whole available window for now.  We will check the
    821	 * disk bitmap later and then, if there are free blocks then we adjust
    822	 * the window size if it's larger than requested.
    823	 * Otherwise, we will remove this node from the tree next time
    824	 * call find_next_reservable_window.
    825	 */
    826	my_rsv->rsv_start = cur;
    827	my_rsv->rsv_end = cur + size - 1;
    828	my_rsv->rsv_alloc_hit = 0;
    829
    830	if (prev != my_rsv)
    831		ext2_rsv_window_add(sb, my_rsv);
    832
    833	return 0;
    834}
    835
    836/**
    837 * 	alloc_new_reservation()--allocate a new reservation window
    838 *
    839 *		To make a new reservation, we search part of the filesystem
    840 *		reservation list (the list that inside the group). We try to
    841 *		allocate a new reservation window near the allocation goal,
    842 *		or the beginning of the group, if there is no goal.
    843 *
    844 *		We first find a reservable space after the goal, then from
    845 *		there, we check the bitmap for the first free block after
    846 *		it. If there is no free block until the end of group, then the
    847 *		whole group is full, we failed. Otherwise, check if the free
    848 *		block is inside the expected reservable space, if so, we
    849 *		succeed.
    850 *		If the first free block is outside the reservable space, then
    851 *		start from the first free block, we search for next available
    852 *		space, and go on.
    853 *
    854 *	on succeed, a new reservation will be found and inserted into the list
    855 *	It contains at least one free block, and it does not overlap with other
    856 *	reservation windows.
    857 *
    858 *	failed: we failed to find a reservation window in this group
    859 *
    860 *	@my_rsv: the reservation
    861 *
    862 *	@grp_goal: The goal (group-relative).  It is where the search for a
    863 *		free reservable space should start from.
    864 *		if we have a goal(goal >0 ), then start from there,
    865 *		no goal(goal = -1), we start from the first block
    866 *		of the group.
    867 *
    868 *	@sb: the super block
    869 *	@group: the group we are trying to allocate in
    870 *	@bitmap_bh: the block group block bitmap
    871 *
    872 */
    873static int alloc_new_reservation(struct ext2_reserve_window_node *my_rsv,
    874		ext2_grpblk_t grp_goal, struct super_block *sb,
    875		unsigned int group, struct buffer_head *bitmap_bh)
    876{
    877	struct ext2_reserve_window_node *search_head;
    878	ext2_fsblk_t group_first_block, group_end_block, start_block;
    879	ext2_grpblk_t first_free_block;
    880	struct rb_root *fs_rsv_root = &EXT2_SB(sb)->s_rsv_window_root;
    881	unsigned long size;
    882	int ret;
    883	spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
    884
    885	group_first_block = ext2_group_first_block_no(sb, group);
    886	group_end_block = ext2_group_last_block_no(sb, group);
    887
    888	if (grp_goal < 0)
    889		start_block = group_first_block;
    890	else
    891		start_block = grp_goal + group_first_block;
    892
    893	size = my_rsv->rsv_goal_size;
    894
    895	if (!rsv_is_empty(&my_rsv->rsv_window)) {
    896		/*
    897		 * if the old reservation is cross group boundary
    898		 * and if the goal is inside the old reservation window,
    899		 * we will come here when we just failed to allocate from
    900		 * the first part of the window. We still have another part
    901		 * that belongs to the next group. In this case, there is no
    902		 * point to discard our window and try to allocate a new one
    903		 * in this group(which will fail). we should
    904		 * keep the reservation window, just simply move on.
    905		 *
    906		 * Maybe we could shift the start block of the reservation
    907		 * window to the first block of next group.
    908		 */
    909
    910		if ((my_rsv->rsv_start <= group_end_block) &&
    911				(my_rsv->rsv_end > group_end_block) &&
    912				(start_block >= my_rsv->rsv_start))
    913			return -1;
    914
    915		if ((my_rsv->rsv_alloc_hit >
    916		     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
    917			/*
    918			 * if the previously allocation hit ratio is
    919			 * greater than 1/2, then we double the size of
    920			 * the reservation window the next time,
    921			 * otherwise we keep the same size window
    922			 */
    923			size = size * 2;
    924			if (size > EXT2_MAX_RESERVE_BLOCKS)
    925				size = EXT2_MAX_RESERVE_BLOCKS;
    926			my_rsv->rsv_goal_size= size;
    927		}
    928	}
    929
    930	spin_lock(rsv_lock);
    931	/*
    932	 * shift the search start to the window near the goal block
    933	 */
    934	search_head = search_reserve_window(fs_rsv_root, start_block);
    935
    936	/*
    937	 * find_next_reservable_window() simply finds a reservable window
    938	 * inside the given range(start_block, group_end_block).
    939	 *
    940	 * To make sure the reservation window has a free bit inside it, we
    941	 * need to check the bitmap after we found a reservable window.
    942	 */
    943retry:
    944	ret = find_next_reservable_window(search_head, my_rsv, sb,
    945						start_block, group_end_block);
    946
    947	if (ret == -1) {
    948		if (!rsv_is_empty(&my_rsv->rsv_window))
    949			rsv_window_remove(sb, my_rsv);
    950		spin_unlock(rsv_lock);
    951		return -1;
    952	}
    953
    954	/*
    955	 * On success, find_next_reservable_window() returns the
    956	 * reservation window where there is a reservable space after it.
    957	 * Before we reserve this reservable space, we need
    958	 * to make sure there is at least a free block inside this region.
    959	 *
    960	 * Search the first free bit on the block bitmap.  Search starts from
    961	 * the start block of the reservable space we just found.
    962	 */
    963	spin_unlock(rsv_lock);
    964	first_free_block = bitmap_search_next_usable_block(
    965			my_rsv->rsv_start - group_first_block,
    966			bitmap_bh, group_end_block - group_first_block + 1);
    967
    968	if (first_free_block < 0) {
    969		/*
    970		 * no free block left on the bitmap, no point
    971		 * to reserve the space. return failed.
    972		 */
    973		spin_lock(rsv_lock);
    974		if (!rsv_is_empty(&my_rsv->rsv_window))
    975			rsv_window_remove(sb, my_rsv);
    976		spin_unlock(rsv_lock);
    977		return -1;		/* failed */
    978	}
    979
    980	start_block = first_free_block + group_first_block;
    981	/*
    982	 * check if the first free block is within the
    983	 * free space we just reserved
    984	 */
    985	if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
    986		return 0;		/* success */
    987	/*
    988	 * if the first free bit we found is out of the reservable space
    989	 * continue search for next reservable space,
    990	 * start from where the free block is,
    991	 * we also shift the list head to where we stopped last time
    992	 */
    993	search_head = my_rsv;
    994	spin_lock(rsv_lock);
    995	goto retry;
    996}
    997
    998/**
    999 * try_to_extend_reservation()
   1000 * @my_rsv:		given reservation window
   1001 * @sb:			super block
   1002 * @size:		the delta to extend
   1003 *
   1004 * Attempt to expand the reservation window large enough to have
   1005 * required number of free blocks
   1006 *
   1007 * Since ext2_try_to_allocate() will always allocate blocks within
   1008 * the reservation window range, if the window size is too small,
   1009 * multiple blocks allocation has to stop at the end of the reservation
   1010 * window. To make this more efficient, given the total number of
   1011 * blocks needed and the current size of the window, we try to
   1012 * expand the reservation window size if necessary on a best-effort
   1013 * basis before ext2_new_blocks() tries to allocate blocks.
   1014 */
   1015static void try_to_extend_reservation(struct ext2_reserve_window_node *my_rsv,
   1016			struct super_block *sb, int size)
   1017{
   1018	struct ext2_reserve_window_node *next_rsv;
   1019	struct rb_node *next;
   1020	spinlock_t *rsv_lock = &EXT2_SB(sb)->s_rsv_window_lock;
   1021
   1022	if (!spin_trylock(rsv_lock))
   1023		return;
   1024
   1025	next = rb_next(&my_rsv->rsv_node);
   1026
   1027	if (!next)
   1028		my_rsv->rsv_end += size;
   1029	else {
   1030		next_rsv = rb_entry(next, struct ext2_reserve_window_node, rsv_node);
   1031
   1032		if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
   1033			my_rsv->rsv_end += size;
   1034		else
   1035			my_rsv->rsv_end = next_rsv->rsv_start - 1;
   1036	}
   1037	spin_unlock(rsv_lock);
   1038}
   1039
   1040/**
   1041 * ext2_try_to_allocate_with_rsv()
   1042 * @sb:			superblock
   1043 * @group:		given allocation block group
   1044 * @bitmap_bh:		bufferhead holds the block bitmap
   1045 * @grp_goal:		given target block within the group
   1046 * @count:		target number of blocks to allocate
   1047 * @my_rsv:		reservation window
   1048 *
   1049 * This is the main function used to allocate a new block and its reservation
   1050 * window.
   1051 *
   1052 * Each time when a new block allocation is need, first try to allocate from
   1053 * its own reservation.  If it does not have a reservation window, instead of
   1054 * looking for a free bit on bitmap first, then look up the reservation list to
   1055 * see if it is inside somebody else's reservation window, we try to allocate a
   1056 * reservation window for it starting from the goal first. Then do the block
   1057 * allocation within the reservation window.
   1058 *
   1059 * This will avoid keeping on searching the reservation list again and
   1060 * again when somebody is looking for a free block (without
   1061 * reservation), and there are lots of free blocks, but they are all
   1062 * being reserved.
   1063 *
   1064 * We use a red-black tree for the per-filesystem reservation list.
   1065 */
   1066static ext2_grpblk_t
   1067ext2_try_to_allocate_with_rsv(struct super_block *sb, unsigned int group,
   1068			struct buffer_head *bitmap_bh, ext2_grpblk_t grp_goal,
   1069			struct ext2_reserve_window_node * my_rsv,
   1070			unsigned long *count)
   1071{
   1072	ext2_fsblk_t group_first_block, group_last_block;
   1073	ext2_grpblk_t ret = 0;
   1074	unsigned long num = *count;
   1075
   1076	/*
   1077	 * we don't deal with reservation when
   1078	 * filesystem is mounted without reservation
   1079	 * or the file is not a regular file
   1080	 * or last attempt to allocate a block with reservation turned on failed
   1081	 */
   1082	if (my_rsv == NULL) {
   1083		return ext2_try_to_allocate(sb, group, bitmap_bh,
   1084						grp_goal, count, NULL);
   1085	}
   1086	/*
   1087	 * grp_goal is a group relative block number (if there is a goal)
   1088	 * 0 <= grp_goal < EXT2_BLOCKS_PER_GROUP(sb)
   1089	 * first block is a filesystem wide block number
   1090	 * first block is the block number of the first block in this group
   1091	 */
   1092	group_first_block = ext2_group_first_block_no(sb, group);
   1093	group_last_block = ext2_group_last_block_no(sb, group);
   1094
   1095	/*
   1096	 * Basically we will allocate a new block from inode's reservation
   1097	 * window.
   1098	 *
   1099	 * We need to allocate a new reservation window, if:
   1100	 * a) inode does not have a reservation window; or
   1101	 * b) last attempt to allocate a block from existing reservation
   1102	 *    failed; or
   1103	 * c) we come here with a goal and with a reservation window
   1104	 *
   1105	 * We do not need to allocate a new reservation window if we come here
   1106	 * at the beginning with a goal and the goal is inside the window, or
   1107	 * we don't have a goal but already have a reservation window.
   1108	 * then we could go to allocate from the reservation window directly.
   1109	 */
   1110	while (1) {
   1111		if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
   1112			!goal_in_my_reservation(&my_rsv->rsv_window,
   1113						grp_goal, group, sb)) {
   1114			if (my_rsv->rsv_goal_size < *count)
   1115				my_rsv->rsv_goal_size = *count;
   1116			ret = alloc_new_reservation(my_rsv, grp_goal, sb,
   1117							group, bitmap_bh);
   1118			if (ret < 0)
   1119				break;			/* failed */
   1120
   1121			if (!goal_in_my_reservation(&my_rsv->rsv_window,
   1122							grp_goal, group, sb))
   1123				grp_goal = -1;
   1124		} else if (grp_goal >= 0) {
   1125			int curr = my_rsv->rsv_end -
   1126					(grp_goal + group_first_block) + 1;
   1127
   1128			if (curr < *count)
   1129				try_to_extend_reservation(my_rsv, sb,
   1130							*count - curr);
   1131		}
   1132
   1133		if ((my_rsv->rsv_start > group_last_block) ||
   1134				(my_rsv->rsv_end < group_first_block)) {
   1135			rsv_window_dump(&EXT2_SB(sb)->s_rsv_window_root, 1);
   1136			BUG();
   1137		}
   1138		ret = ext2_try_to_allocate(sb, group, bitmap_bh, grp_goal,
   1139					   &num, &my_rsv->rsv_window);
   1140		if (ret >= 0) {
   1141			my_rsv->rsv_alloc_hit += num;
   1142			*count = num;
   1143			break;				/* succeed */
   1144		}
   1145		num = *count;
   1146	}
   1147	return ret;
   1148}
   1149
   1150/**
   1151 * ext2_has_free_blocks()
   1152 * @sbi:		in-core super block structure.
   1153 *
   1154 * Check if filesystem has at least 1 free block available for allocation.
   1155 */
   1156static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
   1157{
   1158	ext2_fsblk_t free_blocks, root_blocks;
   1159
   1160	free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
   1161	root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
   1162	if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
   1163		!uid_eq(sbi->s_resuid, current_fsuid()) &&
   1164		(gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
   1165		 !in_group_p (sbi->s_resgid))) {
   1166		return 0;
   1167	}
   1168	return 1;
   1169}
   1170
   1171/*
   1172 * Returns 1 if the passed-in block region is valid; 0 if some part overlaps
   1173 * with filesystem metadata blocks.
   1174 */
   1175int ext2_data_block_valid(struct ext2_sb_info *sbi, ext2_fsblk_t start_blk,
   1176			  unsigned int count)
   1177{
   1178	if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
   1179	    (start_blk + count - 1 < start_blk) ||
   1180	    (start_blk + count - 1 >= le32_to_cpu(sbi->s_es->s_blocks_count)))
   1181		return 0;
   1182
   1183	/* Ensure we do not step over superblock */
   1184	if ((start_blk <= sbi->s_sb_block) &&
   1185	    (start_blk + count - 1 >= sbi->s_sb_block))
   1186		return 0;
   1187
   1188	return 1;
   1189}
   1190
   1191/*
   1192 * ext2_new_blocks() -- core block(s) allocation function
   1193 * @inode:		file inode
   1194 * @goal:		given target block(filesystem wide)
   1195 * @count:		target number of blocks to allocate
   1196 * @errp:		error code
   1197 *
   1198 * ext2_new_blocks uses a goal block to assist allocation.  If the goal is
   1199 * free, or there is a free block within 32 blocks of the goal, that block
   1200 * is allocated.  Otherwise a forward search is made for a free block; within 
   1201 * each block group the search first looks for an entire free byte in the block
   1202 * bitmap, and then for any free bit if that fails.
   1203 * This function also updates quota and i_blocks field.
   1204 */
   1205ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal,
   1206		    unsigned long *count, int *errp)
   1207{
   1208	struct buffer_head *bitmap_bh = NULL;
   1209	struct buffer_head *gdp_bh;
   1210	int group_no;
   1211	int goal_group;
   1212	ext2_grpblk_t grp_target_blk;	/* blockgroup relative goal block */
   1213	ext2_grpblk_t grp_alloc_blk;	/* blockgroup-relative allocated block*/
   1214	ext2_fsblk_t ret_block;		/* filesyetem-wide allocated block */
   1215	int bgi;			/* blockgroup iteration index */
   1216	int performed_allocation = 0;
   1217	ext2_grpblk_t free_blocks;	/* number of free blocks in a group */
   1218	struct super_block *sb;
   1219	struct ext2_group_desc *gdp;
   1220	struct ext2_super_block *es;
   1221	struct ext2_sb_info *sbi;
   1222	struct ext2_reserve_window_node *my_rsv = NULL;
   1223	struct ext2_block_alloc_info *block_i;
   1224	unsigned short windowsz = 0;
   1225	unsigned long ngroups;
   1226	unsigned long num = *count;
   1227	int ret;
   1228
   1229	*errp = -ENOSPC;
   1230	sb = inode->i_sb;
   1231
   1232	/*
   1233	 * Check quota for allocation of this block.
   1234	 */
   1235	ret = dquot_alloc_block(inode, num);
   1236	if (ret) {
   1237		*errp = ret;
   1238		return 0;
   1239	}
   1240
   1241	sbi = EXT2_SB(sb);
   1242	es = EXT2_SB(sb)->s_es;
   1243	ext2_debug("goal=%lu.\n", goal);
   1244	/*
   1245	 * Allocate a block from reservation only when
   1246	 * filesystem is mounted with reservation(default,-o reservation), and
   1247	 * it's a regular file, and
   1248	 * the desired window size is greater than 0 (One could use ioctl
   1249	 * command EXT2_IOC_SETRSVSZ to set the window size to 0 to turn off
   1250	 * reservation on that particular file)
   1251	 */
   1252	block_i = EXT2_I(inode)->i_block_alloc_info;
   1253	if (block_i) {
   1254		windowsz = block_i->rsv_window_node.rsv_goal_size;
   1255		if (windowsz > 0)
   1256			my_rsv = &block_i->rsv_window_node;
   1257	}
   1258
   1259	if (!ext2_has_free_blocks(sbi)) {
   1260		*errp = -ENOSPC;
   1261		goto out;
   1262	}
   1263
   1264	/*
   1265	 * First, test whether the goal block is free.
   1266	 */
   1267	if (goal < le32_to_cpu(es->s_first_data_block) ||
   1268	    goal >= le32_to_cpu(es->s_blocks_count))
   1269		goal = le32_to_cpu(es->s_first_data_block);
   1270	group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
   1271			EXT2_BLOCKS_PER_GROUP(sb);
   1272	goal_group = group_no;
   1273retry_alloc:
   1274	gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
   1275	if (!gdp)
   1276		goto io_error;
   1277
   1278	free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
   1279	/*
   1280	 * if there is not enough free blocks to make a new resevation
   1281	 * turn off reservation for this allocation
   1282	 */
   1283	if (my_rsv && (free_blocks < windowsz)
   1284		&& (free_blocks > 0)
   1285		&& (rsv_is_empty(&my_rsv->rsv_window)))
   1286		my_rsv = NULL;
   1287
   1288	if (free_blocks > 0) {
   1289		grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
   1290				EXT2_BLOCKS_PER_GROUP(sb));
   1291		/*
   1292		 * In case we retry allocation (due to fs reservation not
   1293		 * working out or fs corruption), the bitmap_bh is non-null
   1294		 * pointer and we have to release it before calling
   1295		 * read_block_bitmap().
   1296		 */
   1297		brelse(bitmap_bh);
   1298		bitmap_bh = read_block_bitmap(sb, group_no);
   1299		if (!bitmap_bh)
   1300			goto io_error;
   1301		grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
   1302					bitmap_bh, grp_target_blk,
   1303					my_rsv, &num);
   1304		if (grp_alloc_blk >= 0)
   1305			goto allocated;
   1306	}
   1307
   1308	ngroups = EXT2_SB(sb)->s_groups_count;
   1309	smp_rmb();
   1310
   1311	/*
   1312	 * Now search the rest of the groups.  We assume that
   1313	 * group_no and gdp correctly point to the last group visited.
   1314	 */
   1315	for (bgi = 0; bgi < ngroups; bgi++) {
   1316		group_no++;
   1317		if (group_no >= ngroups)
   1318			group_no = 0;
   1319		gdp = ext2_get_group_desc(sb, group_no, &gdp_bh);
   1320		if (!gdp)
   1321			goto io_error;
   1322
   1323		free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
   1324		/*
   1325		 * skip this group (and avoid loading bitmap) if there
   1326		 * are no free blocks
   1327		 */
   1328		if (!free_blocks)
   1329			continue;
   1330		/*
   1331		 * skip this group if the number of
   1332		 * free blocks is less than half of the reservation
   1333		 * window size.
   1334		 */
   1335		if (my_rsv && (free_blocks <= (windowsz/2)))
   1336			continue;
   1337
   1338		brelse(bitmap_bh);
   1339		bitmap_bh = read_block_bitmap(sb, group_no);
   1340		if (!bitmap_bh)
   1341			goto io_error;
   1342		/*
   1343		 * try to allocate block(s) from this group, without a goal(-1).
   1344		 */
   1345		grp_alloc_blk = ext2_try_to_allocate_with_rsv(sb, group_no,
   1346					bitmap_bh, -1, my_rsv, &num);
   1347		if (grp_alloc_blk >= 0)
   1348			goto allocated;
   1349	}
   1350	/*
   1351	 * We may end up a bogus earlier ENOSPC error due to
   1352	 * filesystem is "full" of reservations, but
   1353	 * there maybe indeed free blocks available on disk
   1354	 * In this case, we just forget about the reservations
   1355	 * just do block allocation as without reservations.
   1356	 */
   1357	if (my_rsv) {
   1358		my_rsv = NULL;
   1359		windowsz = 0;
   1360		group_no = goal_group;
   1361		goto retry_alloc;
   1362	}
   1363	/* No space left on the device */
   1364	*errp = -ENOSPC;
   1365	goto out;
   1366
   1367allocated:
   1368
   1369	ext2_debug("using block group %d(%d)\n",
   1370			group_no, gdp->bg_free_blocks_count);
   1371
   1372	ret_block = grp_alloc_blk + ext2_group_first_block_no(sb, group_no);
   1373
   1374	if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
   1375	    in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
   1376	    in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
   1377		      EXT2_SB(sb)->s_itb_per_group) ||
   1378	    in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
   1379		      EXT2_SB(sb)->s_itb_per_group)) {
   1380		ext2_error(sb, "ext2_new_blocks",
   1381			    "Allocating block in system zone - "
   1382			    "blocks from "E2FSBLK", length %lu",
   1383			    ret_block, num);
   1384		/*
   1385		 * ext2_try_to_allocate marked the blocks we allocated as in
   1386		 * use.  So we may want to selectively mark some of the blocks
   1387		 * as free
   1388		 */
   1389		num = *count;
   1390		goto retry_alloc;
   1391	}
   1392
   1393	performed_allocation = 1;
   1394
   1395	if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
   1396		ext2_error(sb, "ext2_new_blocks",
   1397			    "block("E2FSBLK") >= blocks count(%d) - "
   1398			    "block_group = %d, es == %p ", ret_block,
   1399			le32_to_cpu(es->s_blocks_count), group_no, es);
   1400		goto out;
   1401	}
   1402
   1403	group_adjust_blocks(sb, group_no, gdp, gdp_bh, -num);
   1404	percpu_counter_sub(&sbi->s_freeblocks_counter, num);
   1405
   1406	mark_buffer_dirty(bitmap_bh);
   1407	if (sb->s_flags & SB_SYNCHRONOUS)
   1408		sync_dirty_buffer(bitmap_bh);
   1409
   1410	*errp = 0;
   1411	brelse(bitmap_bh);
   1412	if (num < *count) {
   1413		dquot_free_block_nodirty(inode, *count-num);
   1414		mark_inode_dirty(inode);
   1415		*count = num;
   1416	}
   1417	return ret_block;
   1418
   1419io_error:
   1420	*errp = -EIO;
   1421out:
   1422	/*
   1423	 * Undo the block allocation
   1424	 */
   1425	if (!performed_allocation) {
   1426		dquot_free_block_nodirty(inode, *count);
   1427		mark_inode_dirty(inode);
   1428	}
   1429	brelse(bitmap_bh);
   1430	return 0;
   1431}
   1432
   1433ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
   1434{
   1435	unsigned long count = 1;
   1436
   1437	return ext2_new_blocks(inode, goal, &count, errp);
   1438}
   1439
   1440#ifdef EXT2FS_DEBUG
   1441
   1442unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
   1443{
   1444	return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
   1445}
   1446
   1447#endif  /*  EXT2FS_DEBUG  */
   1448
   1449unsigned long ext2_count_free_blocks (struct super_block * sb)
   1450{
   1451	struct ext2_group_desc * desc;
   1452	unsigned long desc_count = 0;
   1453	int i;
   1454#ifdef EXT2FS_DEBUG
   1455	unsigned long bitmap_count, x;
   1456	struct ext2_super_block *es;
   1457
   1458	es = EXT2_SB(sb)->s_es;
   1459	desc_count = 0;
   1460	bitmap_count = 0;
   1461	desc = NULL;
   1462	for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
   1463		struct buffer_head *bitmap_bh;
   1464		desc = ext2_get_group_desc (sb, i, NULL);
   1465		if (!desc)
   1466			continue;
   1467		desc_count += le16_to_cpu(desc->bg_free_blocks_count);
   1468		bitmap_bh = read_block_bitmap(sb, i);
   1469		if (!bitmap_bh)
   1470			continue;
   1471		
   1472		x = ext2_count_free(bitmap_bh, sb->s_blocksize);
   1473		printk ("group %d: stored = %d, counted = %lu\n",
   1474			i, le16_to_cpu(desc->bg_free_blocks_count), x);
   1475		bitmap_count += x;
   1476		brelse(bitmap_bh);
   1477	}
   1478	printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
   1479		(long)le32_to_cpu(es->s_free_blocks_count),
   1480		desc_count, bitmap_count);
   1481	return bitmap_count;
   1482#else
   1483        for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
   1484                desc = ext2_get_group_desc (sb, i, NULL);
   1485                if (!desc)
   1486                        continue;
   1487                desc_count += le16_to_cpu(desc->bg_free_blocks_count);
   1488	}
   1489	return desc_count;
   1490#endif
   1491}
   1492
   1493static inline int test_root(int a, int b)
   1494{
   1495	int num = b;
   1496
   1497	while (a > num)
   1498		num *= b;
   1499	return num == a;
   1500}
   1501
   1502static int ext2_group_sparse(int group)
   1503{
   1504	if (group <= 1)
   1505		return 1;
   1506	return (test_root(group, 3) || test_root(group, 5) ||
   1507		test_root(group, 7));
   1508}
   1509
   1510/**
   1511 *	ext2_bg_has_super - number of blocks used by the superblock in group
   1512 *	@sb: superblock for filesystem
   1513 *	@group: group number to check
   1514 *
   1515 *	Return the number of blocks used by the superblock (primary or backup)
   1516 *	in this group.  Currently this will be only 0 or 1.
   1517 */
   1518int ext2_bg_has_super(struct super_block *sb, int group)
   1519{
   1520	if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
   1521	    !ext2_group_sparse(group))
   1522		return 0;
   1523	return 1;
   1524}
   1525
   1526/**
   1527 *	ext2_bg_num_gdb - number of blocks used by the group table in group
   1528 *	@sb: superblock for filesystem
   1529 *	@group: group number to check
   1530 *
   1531 *	Return the number of blocks used by the group descriptor table
   1532 *	(primary or backup) in this group.  In the future there may be a
   1533 *	different number of descriptor blocks in each group.
   1534 */
   1535unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
   1536{
   1537	return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
   1538}
   1539