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root/fs/minix/bitmap.c

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DEFINITIONS

This source file includes following definitions.
  1. count_free
  2. minix_free_block
  3. minix_new_block
  4. minix_count_free_blocks
  5. minix_V1_raw_inode
  6. minix_V2_raw_inode
  7. minix_clear_inode
  8. minix_free_inode
  9. minix_new_inode
  10. minix_count_free_inodes

/*
 *  linux/fs/minix/bitmap.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * Modified for 680x0 by Hamish Macdonald
 * Fixed for 680x0 by Andreas Schwab
 */

/* bitmap.c contains the code that handles the inode and block bitmaps */

#include "minix.h"
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>
#include <linux/bitops.h>
#include <linux/sched.h>

static const int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 };

static unsigned long count_free(struct buffer_head *map[], unsigned numblocks, __u32 numbits)
{
        unsigned i, j, sum = 0;
        struct buffer_head *bh;
  
        for (i=0; i<numblocks-1; i++) {
                if (!(bh=map[i])) 
                        return(0);
                for (j=0; j<bh->b_size; j++)
                        sum += nibblemap[bh->b_data[j] & 0xf]
                                + nibblemap[(bh->b_data[j]>>4) & 0xf];
        }

        if (numblocks==0 || !(bh=map[numblocks-1]))
                return(0);
        i = ((numbits - (numblocks-1) * bh->b_size * 8) / 16) * 2;
        for (j=0; j<i; j++) {
                sum += nibblemap[bh->b_data[j] & 0xf]
                        + nibblemap[(bh->b_data[j]>>4) & 0xf];
        }

        i = numbits%16;
        if (i!=0) {
                i = *(__u16 *)(&bh->b_data[j]) | ~((1<<i) - 1);
                sum += nibblemap[i & 0xf] + nibblemap[(i>>4) & 0xf];
                sum += nibblemap[(i>>8) & 0xf] + nibblemap[(i>>12) & 0xf];
        }
        return(sum);
}

void minix_free_block(struct inode *inode, unsigned long block)
{
        struct super_block *sb = inode->i_sb;
        struct minix_sb_info *sbi = minix_sb(sb);
        struct buffer_head *bh;
        int k = sb->s_blocksize_bits + 3;
        unsigned long bit, zone;

        if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
                printk("Trying to free block not in datazone\n");
                return;
        }
        zone = block - sbi->s_firstdatazone + 1;
        bit = zone & ((1<<k) - 1);
        zone >>= k;
        if (zone >= sbi->s_zmap_blocks) {
                printk("minix_free_block: nonexistent bitmap buffer\n");
                return;
        }
        bh = sbi->s_zmap[zone];
        lock_kernel();
        if (!minix_test_and_clear_bit(bit, bh->b_data))
                printk("minix_free_block (%s:%lu): bit already cleared\n",
                       sb->s_id, block);
        unlock_kernel();
        mark_buffer_dirty(bh);
        return;
}

int minix_new_block(struct inode * inode)
{
        struct minix_sb_info *sbi = minix_sb(inode->i_sb);
        int bits_per_zone = 8 * inode->i_sb->s_blocksize;
        int i;

        for (i = 0; i < sbi->s_zmap_blocks; i++) {
                struct buffer_head *bh = sbi->s_zmap[i];
                int j;

                lock_kernel();
                j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
                if (j < bits_per_zone) {
                        minix_set_bit(j, bh->b_data);
                        unlock_kernel();
                        mark_buffer_dirty(bh);
                        j += i * bits_per_zone + sbi->s_firstdatazone-1;
                        if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
                                break;
                        return j;
                }
                unlock_kernel();
        }
        return 0;
}

unsigned long minix_count_free_blocks(struct minix_sb_info *sbi)
{
        return (count_free(sbi->s_zmap, sbi->s_zmap_blocks,
                sbi->s_nzones - sbi->s_firstdatazone + 1)
                << sbi->s_log_zone_size);
}

struct minix_inode *
minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
{
        int block;
        struct minix_sb_info *sbi = minix_sb(sb);
        struct minix_inode *p;

        if (!ino || ino > sbi->s_ninodes) {
                printk("Bad inode number on dev %s: %ld is out of range\n",
                       sb->s_id, (long)ino);
                return NULL;
        }
        ino--;
        block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
                 ino / MINIX_INODES_PER_BLOCK;
        *bh = sb_bread(sb, block);
        if (!*bh) {
                printk("Unable to read inode block\n");
                return NULL;
        }
        p = (void *)(*bh)->b_data;
        return p + ino % MINIX_INODES_PER_BLOCK;
}

struct minix2_inode *
minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
{
        int block;
        struct minix_sb_info *sbi = minix_sb(sb);
        struct minix2_inode *p;
        int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);

        *bh = NULL;
        if (!ino || ino > sbi->s_ninodes) {
                printk("Bad inode number on dev %s: %ld is out of range\n",
                       sb->s_id, (long)ino);
                return NULL;
        }
        ino--;
        block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
                 ino / minix2_inodes_per_block;
        *bh = sb_bread(sb, block);
        if (!*bh) {
                printk("Unable to read inode block\n");
                return NULL;
        }
        p = (void *)(*bh)->b_data;
        return p + ino % minix2_inodes_per_block;
}

/* Clear the link count and mode of a deleted inode on disk. */

static void minix_clear_inode(struct inode *inode)
{
        struct buffer_head *bh = NULL;

        if (INODE_VERSION(inode) == MINIX_V1) {
                struct minix_inode *raw_inode;
                raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
                if (raw_inode) {
                        raw_inode->i_nlinks = 0;
                        raw_inode->i_mode = 0;
                }
        } else {
                struct minix2_inode *raw_inode;
                raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
                if (raw_inode) {
                        raw_inode->i_nlinks = 0;
                        raw_inode->i_mode = 0;
                }
        }
        if (bh) {
                mark_buffer_dirty(bh);
                brelse (bh);
        }
}

void minix_free_inode(struct inode * inode)
{
        struct super_block *sb = inode->i_sb;
        struct minix_sb_info *sbi = minix_sb(inode->i_sb);
        struct buffer_head *bh;
        int k = sb->s_blocksize_bits + 3;
        unsigned long ino, bit;

        ino = inode->i_ino;
        if (ino < 1 || ino > sbi->s_ninodes) {
                printk("minix_free_inode: inode 0 or nonexistent inode\n");
                goto out;
        }
        bit = ino & ((1<<k) - 1);
        ino >>= k;
        if (ino >= sbi->s_imap_blocks) {
                printk("minix_free_inode: nonexistent imap in superblock\n");
                goto out;
        }

        minix_clear_inode(inode);       /* clear on-disk copy */

        bh = sbi->s_imap[ino];
        lock_kernel();
        if (!minix_test_and_clear_bit(bit, bh->b_data))
                printk("minix_free_inode: bit %lu already cleared\n", bit);
        unlock_kernel();
        mark_buffer_dirty(bh);
 out:
        clear_inode(inode);             /* clear in-memory copy */
}

struct inode * minix_new_inode(const struct inode * dir, int * error)
{
        struct super_block *sb = dir->i_sb;
        struct minix_sb_info *sbi = minix_sb(sb);
        struct inode *inode = new_inode(sb);
        struct buffer_head * bh;
        int bits_per_zone = 8 * sb->s_blocksize;
        unsigned long j;
        int i;

        if (!inode) {
                *error = -ENOMEM;
                return NULL;
        }
        j = bits_per_zone;
        bh = NULL;
        *error = -ENOSPC;
        lock_kernel();
        for (i = 0; i < sbi->s_imap_blocks; i++) {
                bh = sbi->s_imap[i];
                j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
                if (j < bits_per_zone)
                        break;
        }
        if (!bh || j >= bits_per_zone) {
                unlock_kernel();
                iput(inode);
                return NULL;
        }
        if (minix_test_and_set_bit(j, bh->b_data)) {    /* shouldn't happen */
                unlock_kernel();
                printk("minix_new_inode: bit already set\n");
                iput(inode);
                return NULL;
        }
        unlock_kernel();
        mark_buffer_dirty(bh);
        j += i * bits_per_zone;
        if (!j || j > sbi->s_ninodes) {
                iput(inode);
                return NULL;
        }
        inode->i_uid = current->fsuid;
        inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current->fsgid;
        inode->i_ino = j;
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
        inode->i_blocks = 0;
        memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
        insert_inode_hash(inode);
        mark_inode_dirty(inode);

        *error = 0;
        return inode;
}

unsigned long minix_count_free_inodes(struct minix_sb_info *sbi)
{
        return count_free(sbi->s_imap, sbi->s_imap_blocks, sbi->s_ninodes + 1);
}

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