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freebsd/sys/gnu/fs/ext2fs/ext2_linux_balloc.c
Jens Schweikhardt d64ada501a Fix typos, mostly s/ an / a / where appropriate and a few s/an/and/ 
Add FreeBSD Id tag where missing.
2002-12-30 21:18:15 +00:00

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/*
* modified for Lites 1.1
*
* Aug 1995, Godmar Back (gback@cs.utah.edu)
* University of Utah, Department of Computer Science
*
* $FreeBSD$
*/
/*
* linux/fs/ext2/balloc.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* Enhanced block allocation by Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
*/
/*
* The free blocks are managed by bitmaps. A file system contains several
* blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
* block for inodes, N blocks for the inode table and data blocks.
*
* The file system contains group descriptors which are located after the
* super block. Each descriptor contains the number of the bitmap block and
* the free blocks count in the block. The descriptors are loaded in memory
* when a file system is mounted (see ext2_read_super).
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <gnu/ext2fs/inode.h>
#include <gnu/ext2fs/ext2_mount.h>
#include <gnu/ext2fs/ext2_extern.h>
#include <gnu/ext2fs/ext2_fs.h>
#include <gnu/ext2fs/ext2_fs_sb.h>
#include <gnu/ext2fs/fs.h>
#ifdef __i386__
#include <gnu/ext2fs/i386-bitops.h>
#elif __alpha__
#include <gnu/ext2fs/alpha-bitops.h>
#else
#error Provide a bitops.h file, please!
#endif
#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
/* got rid of get_group_desc since it can already be found in
* ext2_linux_ialloc.c
*/
static void read_block_bitmap (struct mount * mp,
unsigned int block_group,
unsigned long bitmap_nr)
{
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
struct ext2_group_desc * gdp;
struct buffer_head * bh;
int error;
gdp = get_group_desc (mp, block_group, NULL);
if ((error = bread (VFSTOEXT2(mp)->um_devvp,
fsbtodb(sb, gdp->bg_block_bitmap),sb->s_blocksize, NOCRED, &bh)) != 0)
panic ( "read_block_bitmap: "
"Cannot read block bitmap - "
"block_group = %d, block_bitmap = %lu",
block_group, (unsigned long) gdp->bg_block_bitmap);
sb->s_block_bitmap_number[bitmap_nr] = block_group;
sb->s_block_bitmap[bitmap_nr] = bh;
LCK_BUF(bh)
}
/*
* load_block_bitmap loads the block bitmap for a blocks group
*
* It maintains a cache for the last bitmaps loaded. This cache is managed
* with a LRU algorithm.
*
* Notes:
* 1/ There is one cache per mounted file system.
* 2/ If the file system contains less than EXT2_MAX_GROUP_LOADED groups,
* this function reads the bitmap without maintaining a LRU cache.
*/
static int load__block_bitmap (struct mount * mp,
unsigned int block_group)
{
int i, j;
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
unsigned long block_bitmap_number;
struct buffer_head * block_bitmap;
if (block_group >= sb->s_groups_count)
panic ( "load_block_bitmap: "
"block_group >= groups_count - "
"block_group = %d, groups_count = %lu",
block_group, sb->s_groups_count);
if (sb->s_groups_count <= EXT2_MAX_GROUP_LOADED) {
if (sb->s_block_bitmap[block_group]) {
if (sb->s_block_bitmap_number[block_group] !=
block_group)
panic ( "load_block_bitmap: "
"block_group != block_bitmap_number");
else
return block_group;
} else {
read_block_bitmap (mp, block_group, block_group);
return block_group;
}
}
for (i = 0; i < sb->s_loaded_block_bitmaps &&
sb->s_block_bitmap_number[i] != block_group; i++)
;
if (i < sb->s_loaded_block_bitmaps &&
sb->s_block_bitmap_number[i] == block_group) {
block_bitmap_number = sb->s_block_bitmap_number[i];
block_bitmap = sb->s_block_bitmap[i];
for (j = i; j > 0; j--) {
sb->s_block_bitmap_number[j] =
sb->s_block_bitmap_number[j - 1];
sb->s_block_bitmap[j] =
sb->s_block_bitmap[j - 1];
}
sb->s_block_bitmap_number[0] = block_bitmap_number;
sb->s_block_bitmap[0] = block_bitmap;
} else {
if (sb->s_loaded_block_bitmaps < EXT2_MAX_GROUP_LOADED)
sb->s_loaded_block_bitmaps++;
else
ULCK_BUF(sb->s_block_bitmap[EXT2_MAX_GROUP_LOADED - 1])
for (j = sb->s_loaded_block_bitmaps - 1; j > 0; j--) {
sb->s_block_bitmap_number[j] =
sb->s_block_bitmap_number[j - 1];
sb->s_block_bitmap[j] =
sb->s_block_bitmap[j - 1];
}
read_block_bitmap (mp, block_group, 0);
}
return 0;
}
static __inline int load_block_bitmap (struct mount * mp,
unsigned int block_group)
{
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
if (sb->s_loaded_block_bitmaps > 0 &&
sb->s_block_bitmap_number[0] == block_group)
return 0;
if (sb->s_groups_count <= EXT2_MAX_GROUP_LOADED &&
sb->s_block_bitmap_number[block_group] == block_group &&
sb->s_block_bitmap[block_group])
return block_group;
return load__block_bitmap (mp, block_group);
}
void ext2_free_blocks (struct mount * mp, unsigned long block,
unsigned long count)
{
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
struct buffer_head * bh;
struct buffer_head * bh2;
unsigned long block_group;
unsigned long bit;
unsigned long i;
int bitmap_nr;
struct ext2_group_desc * gdp;
struct ext2_super_block * es = sb->s_es;
if (!sb) {
printf ("ext2_free_blocks: nonexistent device");
return;
}
lock_super (VFSTOEXT2(mp)->um_devvp);
if (block < es->s_first_data_block ||
(block + count) > es->s_blocks_count) {
printf ( "ext2_free_blocks: "
"Freeing blocks not in datazone - "
"block = %lu, count = %lu", block, count);
unlock_super (VFSTOEXT2(mp)->um_devvp);
return;
}
ext2_debug ("freeing blocks %lu to %lu\n", block, block+count-1);
block_group = (block - es->s_first_data_block) /
EXT2_BLOCKS_PER_GROUP(sb);
bit = (block - es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb);
if (bit + count > EXT2_BLOCKS_PER_GROUP(sb))
panic ( "ext2_free_blocks: "
"Freeing blocks across group boundary - "
"Block = %lu, count = %lu",
block, count);
bitmap_nr = load_block_bitmap (mp, block_group);
bh = sb->s_block_bitmap[bitmap_nr];
gdp = get_group_desc (mp, block_group, &bh2);
if (/* test_opt (sb, CHECK_STRICT) && assume always strict ! */
(in_range (gdp->bg_block_bitmap, block, count) ||
in_range (gdp->bg_inode_bitmap, block, count) ||
in_range (block, gdp->bg_inode_table,
sb->s_itb_per_group) ||
in_range (block + count - 1, gdp->bg_inode_table,
sb->s_itb_per_group)))
panic ( "ext2_free_blocks: "
"Freeing blocks in system zones - "
"Block = %lu, count = %lu",
block, count);
for (i = 0; i < count; i++) {
if (!clear_bit (bit + i, bh->b_data))
printf ("ext2_free_blocks: "
"bit already cleared for block %lu",
block);
else {
gdp->bg_free_blocks_count++;
es->s_free_blocks_count++;
}
}
mark_buffer_dirty(bh2);
mark_buffer_dirty(bh);
/****
if (sb->s_flags & MS_SYNCHRONOUS) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
****/
sb->s_dirt = 1;
unlock_super (VFSTOEXT2(mp)->um_devvp);
return;
}
/*
* ext2_new_block uses a goal block to assist allocation. If the goal is
* free, or there is a free block within 32 blocks of the goal, that block
* is allocated. Otherwise a forward search is made for a free block; within
* each block group the search first looks for an entire free byte in the block
* bitmap, and then for any free bit if that fails.
*/
int ext2_new_block (struct mount * mp, unsigned long goal,
u_int32_t * prealloc_count,
u_int32_t * prealloc_block)
{
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
struct buffer_head * bh;
struct buffer_head * bh2;
char * p, * r;
int i, j, k, tmp;
int bitmap_nr;
struct ext2_group_desc * gdp;
struct ext2_super_block * es = sb->s_es;
#ifdef EXT2FS_DEBUG
static int goal_hits = 0, goal_attempts = 0;
#endif
if (!sb) {
printf ("ext2_new_block: nonexistent device");
return 0;
}
lock_super (VFSTOEXT2(mp)->um_devvp);
ext2_debug ("goal=%lu.\n", goal);
repeat:
/*
* First, test whether the goal block is free.
*/
if (goal < es->s_first_data_block || goal >= es->s_blocks_count)
goal = es->s_first_data_block;
i = (goal - es->s_first_data_block) / EXT2_BLOCKS_PER_GROUP(sb);
gdp = get_group_desc (mp, i, &bh2);
if (gdp->bg_free_blocks_count > 0) {
j = ((goal - es->s_first_data_block) % EXT2_BLOCKS_PER_GROUP(sb));
#ifdef EXT2FS_DEBUG
if (j)
goal_attempts++;
#endif
bitmap_nr = load_block_bitmap (mp, i);
bh = sb->s_block_bitmap[bitmap_nr];
ext2_debug ("goal is at %d:%d.\n", i, j);
if (!test_bit(j, bh->b_data)) {
#ifdef EXT2FS_DEBUG
goal_hits++;
ext2_debug ("goal bit allocated.\n");
#endif
goto got_block;
}
if (j) {
/*
* The goal was occupied; search forward for a free
* block within the next XX blocks.
*
* end_goal is more or less random, but it has to be
* less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
* next 64-bit boundary is simple..
*/
int end_goal = (j + 63) & ~63;
j = find_next_zero_bit(bh->b_data, end_goal, j);
if (j < end_goal)
goto got_block;
}
ext2_debug ("Bit not found near goal\n");
/*
* There has been no free block found in the near vicinity
* of the goal: do a search forward through the block groups,
* searching in each group first for an entire free byte in
* the bitmap and then for any free bit.
*
* Search first in the remainder of the current group; then,
* cyclicly search through the rest of the groups.
*/
p = ((char *) bh->b_data) + (j >> 3);
r = memscan(p, 0, (EXT2_BLOCKS_PER_GROUP(sb) - j + 7) >> 3);
k = (r - ((char *) bh->b_data)) << 3;
if (k < EXT2_BLOCKS_PER_GROUP(sb)) {
j = k;
goto search_back;
}
k = find_next_zero_bit ((unsigned long *) bh->b_data,
EXT2_BLOCKS_PER_GROUP(sb),
j);
if (k < EXT2_BLOCKS_PER_GROUP(sb)) {
j = k;
goto got_block;
}
}
ext2_debug ("Bit not found in block group %d.\n", i);
/*
* Now search the rest of the groups. We assume that
* i and gdp correctly point to the last group visited.
*/
for (k = 0; k < sb->s_groups_count; k++) {
i++;
if (i >= sb->s_groups_count)
i = 0;
gdp = get_group_desc (mp, i, &bh2);
if (gdp->bg_free_blocks_count > 0)
break;
}
if (k >= sb->s_groups_count) {
unlock_super (VFSTOEXT2(mp)->um_devvp);
return 0;
}
bitmap_nr = load_block_bitmap (mp, i);
bh = sb->s_block_bitmap[bitmap_nr];
r = memscan(bh->b_data, 0, EXT2_BLOCKS_PER_GROUP(sb) >> 3);
j = (r - bh->b_data) << 3;
if (j < EXT2_BLOCKS_PER_GROUP(sb))
goto search_back;
else
j = find_first_zero_bit ((unsigned long *) bh->b_data,
EXT2_BLOCKS_PER_GROUP(sb));
if (j >= EXT2_BLOCKS_PER_GROUP(sb)) {
printf ( "ext2_new_block: "
"Free blocks count corrupted for block group %d", i);
unlock_super (VFSTOEXT2(mp)->um_devvp);
return 0;
}
search_back:
/*
* We have succeeded in finding a free byte in the block
* bitmap. Now search backwards up to 7 bits to find the
* start of this group of free blocks.
*/
for (k = 0; k < 7 && j > 0 && !test_bit (j - 1, bh->b_data); k++, j--);
got_block:
ext2_debug ("using block group %d(%d)\n", i, gdp->bg_free_blocks_count);
tmp = j + i * EXT2_BLOCKS_PER_GROUP(sb) + es->s_first_data_block;
if (/* test_opt (sb, CHECK_STRICT) && we are always strict. */
(tmp == gdp->bg_block_bitmap ||
tmp == gdp->bg_inode_bitmap ||
in_range (tmp, gdp->bg_inode_table, sb->s_itb_per_group)))
panic ( "ext2_new_block: "
"Allocating block in system zone - "
"%dth block = %u in group %u", j, tmp, i);
if (set_bit (j, bh->b_data)) {
printf ( "ext2_new_block: "
"bit already set for block %d", j);
goto repeat;
}
ext2_debug ("found bit %d\n", j);
/*
* Do block preallocation now if required.
*/
#ifdef EXT2_PREALLOCATE
if (prealloc_block) {
*prealloc_count = 0;
*prealloc_block = tmp + 1;
for (k = 1;
k < 8 && (j + k) < EXT2_BLOCKS_PER_GROUP(sb); k++) {
if (set_bit (j + k, bh->b_data))
break;
(*prealloc_count)++;
}
gdp->bg_free_blocks_count -= *prealloc_count;
es->s_free_blocks_count -= *prealloc_count;
ext2_debug ("Preallocated a further %lu bits.\n",
*prealloc_count);
}
#endif
j = tmp;
mark_buffer_dirty(bh);
/****
if (sb->s_flags & MS_SYNCHRONOUS) {
ll_rw_block (WRITE, 1, &bh);
wait_on_buffer (bh);
}
****/
if (j >= es->s_blocks_count) {
printf ( "ext2_new_block: "
"block >= blocks count - "
"block_group = %d, block=%d", i, j);
unlock_super (VFSTOEXT2(mp)->um_devvp);
return 0;
}
ext2_debug ("allocating block %d. "
"Goal hits %d of %d.\n", j, goal_hits, goal_attempts);
gdp->bg_free_blocks_count--;
mark_buffer_dirty(bh2);
es->s_free_blocks_count--;
sb->s_dirt = 1;
unlock_super (VFSTOEXT2(mp)->um_devvp);
return j;
}
#ifdef unused
static unsigned long ext2_count_free_blocks (struct mount * mp)
{
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
#ifdef EXT2FS_DEBUG
struct ext2_super_block * es;
unsigned long desc_count, bitmap_count, x;
int bitmap_nr;
struct ext2_group_desc * gdp;
int i;
lock_super (VFSTOEXT2(mp)->um_devvp);
es = sb->s_es;
desc_count = 0;
bitmap_count = 0;
gdp = NULL;
for (i = 0; i < sb->s_groups_count; i++) {
gdp = get_group_desc (mp, i, NULL);
desc_count += gdp->bg_free_blocks_count;
bitmap_nr = load_block_bitmap (mp, i);
x = ext2_count_free (sb->s_block_bitmap[bitmap_nr],
sb->s_blocksize);
ext2_debug ("group %d: stored = %d, counted = %lu\n",
i, gdp->bg_free_blocks_count, x);
bitmap_count += x;
}
ext2_debug( "stored = %lu, computed = %lu, %lu\n",
es->s_free_blocks_count, desc_count, bitmap_count);
unlock_super (VFSTOEXT2(mp)->um_devvp);
return bitmap_count;
#else
return sb->s_es->s_free_blocks_count;
#endif
}
#endif /* unused */
static __inline int block_in_use (unsigned long block,
struct ext2_sb_info * sb,
unsigned char * map)
{
return test_bit ((block - sb->s_es->s_first_data_block) %
EXT2_BLOCKS_PER_GROUP(sb), map);
}
static int test_root(int a, int b)
{
if (a == 0)
return 1;
while (1) {
if (a == 1)
return 1;
if (a % b)
return 0;
a = a / b;
}
}
int ext2_group_sparse(int group)
{
return (test_root(group, 3) || test_root(group, 5) ||
test_root(group, 7));
}
#ifdef unused
static void ext2_check_blocks_bitmap (struct mount * mp)
{
struct ext2_sb_info *sb = VFSTOEXT2(mp)->um_e2fs;
struct buffer_head * bh;
struct ext2_super_block * es;
unsigned long desc_count, bitmap_count, x;
unsigned long desc_blocks;
int bitmap_nr;
struct ext2_group_desc * gdp;
int i, j;
lock_super (VFSTOEXT2(mp)->um_devvp);
es = sb->s_es;
desc_count = 0;
bitmap_count = 0;
gdp = NULL;
desc_blocks = (sb->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
EXT2_DESC_PER_BLOCK(sb);
for (i = 0; i < sb->s_groups_count; i++) {
gdp = get_group_desc (mp, i, NULL);
desc_count += gdp->bg_free_blocks_count;
bitmap_nr = load_block_bitmap (mp, i);
bh = sb->s_block_bitmap[bitmap_nr];
if (!(es->s_feature_ro_compat &
EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER) ||
ext2_group_sparse(i)) {
if (!test_bit (0, bh->b_data))
printf ("ext2_check_blocks_bitmap: "
"Superblock in group %d "
"is marked free", i);
for (j = 0; j < desc_blocks; j++)
if (!test_bit (j + 1, bh->b_data))
printf ("ext2_check_blocks_bitmap: "
"Descriptor block #%d in group "
"%d is marked free", j, i);
}
if (!block_in_use (gdp->bg_block_bitmap, sb, bh->b_data))
printf ("ext2_check_blocks_bitmap: "
"Block bitmap for group %d is marked free",
i);
if (!block_in_use (gdp->bg_inode_bitmap, sb, bh->b_data))
printf ("ext2_check_blocks_bitmap: "
"Inode bitmap for group %d is marked free",
i);
for (j = 0; j < sb->s_itb_per_group; j++)
if (!block_in_use (gdp->bg_inode_table + j, sb, bh->b_data))
printf ("ext2_check_blocks_bitmap: "
"Block #%d of the inode table in "
"group %d is marked free", j, i);
x = ext2_count_free (bh, sb->s_blocksize);
if (gdp->bg_free_blocks_count != x)
printf ("ext2_check_blocks_bitmap: "
"Wrong free blocks count for group %d, "
"stored = %d, counted = %lu", i,
gdp->bg_free_blocks_count, x);
bitmap_count += x;
}
if (es->s_free_blocks_count != bitmap_count)
printf ("ext2_check_blocks_bitmap: "
"Wrong free blocks count in super block, "
"stored = %lu, counted = %lu",
(unsigned long) es->s_free_blocks_count, bitmap_count);
unlock_super (VFSTOEXT2(mp)->um_devvp);
}
#endif /* unused */
/*
* this function is taken from
* linux/fs/ext2/bitmap.c
*/
static int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
{
unsigned int i;
unsigned long sum = 0;
if (!map)
return (0);
for (i = 0; i < numchars; i++)
sum += nibblemap[map->b_data[i] & 0xf] +
nibblemap[(map->b_data[i] >> 4) & 0xf];
return (sum);
}
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