fs/minix/bitmap.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  linux/fs/minix/bitmap.c
0004  *
0005  *  Copyright (C) 1991, 1992  Linus Torvalds
0006  */
0007
0008 /*
0009  * Modified for 680x0 by Hamish Macdonald
0010  * Fixed for 680x0 by Andreas Schwab
0011  */
0012
0013 /* bitmap.c contains the code that handles the inode and block bitmaps */
0014
0015 #include "minix.h"
0016 #include <linux/buffer_head.h>
0017 #include <linux/bitops.h>
0018 #include <linux/sched.h>
0019
0020 static DEFINE_SPINLOCK(bitmap_lock);
0021
0022 /*
0023  * bitmap consists of blocks filled with 16bit words
0024  * bit set == busy, bit clear == free
0025  * endianness is a mess, but for counting zero bits it really doesn't matter...
0026  */
0027 static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
0028 {
0029     __u32 sum = 0;
0030     unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);
0031
0032     while (blocks--) {
0033         unsigned words = blocksize / 2;
0034         __u16 *p = (__u16 *)(*map++)->b_data;
0035         while (words--)
0036             sum += 16 - hweight16(*p++);
0037     }
0038
0039     return sum;
0040 }
0041
0042 void minix_free_block(struct inode *inode, unsigned long block)
0043 {
0044     struct super_block *sb = inode->i_sb;
0045     struct minix_sb_info *sbi = minix_sb(sb);
0046     struct buffer_head *bh;
0047     int k = sb->s_blocksize_bits + 3;
0048     unsigned long bit, zone;
0049
0050     if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
0051         printk("Trying to free block not in datazone\n");
0052         return;
0053     }
0054     zone = block - sbi->s_firstdatazone + 1;
0055     bit = zone & ((1<<k) - 1);
0056     zone >>= k;
0057     if (zone >= sbi->s_zmap_blocks) {
0058         printk("minix_free_block: nonexistent bitmap buffer\n");
0059         return;
0060     }
0061     bh = sbi->s_zmap[zone];
0062     spin_lock(&bitmap_lock);
0063     if (!minix_test_and_clear_bit(bit, bh->b_data))
0064         printk("minix_free_block (%s:%lu): bit already cleared\n",
0065                sb->s_id, block);
0066     spin_unlock(&bitmap_lock);
0067     mark_buffer_dirty(bh);
0068     return;
0069 }
0070
0071 int minix_new_block(struct inode * inode)
0072 {
0073     struct minix_sb_info *sbi = minix_sb(inode->i_sb);
0074     int bits_per_zone = 8 * inode->i_sb->s_blocksize;
0075     int i;
0076
0077     for (i = 0; i < sbi->s_zmap_blocks; i++) {
0078         struct buffer_head *bh = sbi->s_zmap[i];
0079         int j;
0080
0081         spin_lock(&bitmap_lock);
0082         j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
0083         if (j < bits_per_zone) {
0084             minix_set_bit(j, bh->b_data);
0085             spin_unlock(&bitmap_lock);
0086             mark_buffer_dirty(bh);
0087             j += i * bits_per_zone + sbi->s_firstdatazone-1;
0088             if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
0089                 break;
0090             return j;
0091         }
0092         spin_unlock(&bitmap_lock);
0093     }
0094     return 0;
0095 }
0096
0097 unsigned long minix_count_free_blocks(struct super_block *sb)
0098 {
0099     struct minix_sb_info *sbi = minix_sb(sb);
0100     u32 bits = sbi->s_nzones - sbi->s_firstdatazone + 1;
0101
0102     return (count_free(sbi->s_zmap, sb->s_blocksize, bits)
0103         << sbi->s_log_zone_size);
0104 }
0105
0106 struct minix_inode *
0107 minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
0108 {
0109     int block;
0110     struct minix_sb_info *sbi = minix_sb(sb);
0111     struct minix_inode *p;
0112
0113     if (!ino || ino > sbi->s_ninodes) {
0114         printk("Bad inode number on dev %s: %ld is out of range\n",
0115                sb->s_id, (long)ino);
0116         return NULL;
0117     }
0118     ino--;
0119     block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
0120          ino / MINIX_INODES_PER_BLOCK;
0121     *bh = sb_bread(sb, block);
0122     if (!*bh) {
0123         printk("Unable to read inode block\n");
0124         return NULL;
0125     }
0126     p = (void *)(*bh)->b_data;
0127     return p + ino % MINIX_INODES_PER_BLOCK;
0128 }
0129
0130 struct minix2_inode *
0131 minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
0132 {
0133     int block;
0134     struct minix_sb_info *sbi = minix_sb(sb);
0135     struct minix2_inode *p;
0136     int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);
0137
0138     *bh = NULL;
0139     if (!ino || ino > sbi->s_ninodes) {
0140         printk("Bad inode number on dev %s: %ld is out of range\n",
0141                sb->s_id, (long)ino);
0142         return NULL;
0143     }
0144     ino--;
0145     block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
0146          ino / minix2_inodes_per_block;
0147     *bh = sb_bread(sb, block);
0148     if (!*bh) {
0149         printk("Unable to read inode block\n");
0150         return NULL;
0151     }
0152     p = (void *)(*bh)->b_data;
0153     return p + ino % minix2_inodes_per_block;
0154 }
0155
0156 /* Clear the link count and mode of a deleted inode on disk. */
0157
0158 static void minix_clear_inode(struct inode *inode)
0159 {
0160     struct buffer_head *bh = NULL;
0161
0162     if (INODE_VERSION(inode) == MINIX_V1) {
0163         struct minix_inode *raw_inode;
0164         raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
0165         if (raw_inode) {
0166             raw_inode->i_nlinks = 0;
0167             raw_inode->i_mode = 0;
0168         }
0169     } else {
0170         struct minix2_inode *raw_inode;
0171         raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
0172         if (raw_inode) {
0173             raw_inode->i_nlinks = 0;
0174             raw_inode->i_mode = 0;
0175         }
0176     }
0177     if (bh) {
0178         mark_buffer_dirty(bh);
0179         brelse (bh);
0180     }
0181 }
0182
0183 void minix_free_inode(struct inode * inode)
0184 {
0185     struct super_block *sb = inode->i_sb;
0186     struct minix_sb_info *sbi = minix_sb(inode->i_sb);
0187     struct buffer_head *bh;
0188     int k = sb->s_blocksize_bits + 3;
0189     unsigned long ino, bit;
0190
0191     ino = inode->i_ino;
0192     if (ino < 1 || ino > sbi->s_ninodes) {
0193         printk("minix_free_inode: inode 0 or nonexistent inode\n");
0194         return;
0195     }
0196     bit = ino & ((1<<k) - 1);
0197     ino >>= k;
0198     if (ino >= sbi->s_imap_blocks) {
0199         printk("minix_free_inode: nonexistent imap in superblock\n");
0200         return;
0201     }
0202
0203     minix_clear_inode(inode);   /* clear on-disk copy */
0204
0205     bh = sbi->s_imap[ino];
0206     spin_lock(&bitmap_lock);
0207     if (!minix_test_and_clear_bit(bit, bh->b_data))
0208         printk("minix_free_inode: bit %lu already cleared\n", bit);
0209     spin_unlock(&bitmap_lock);
0210     mark_buffer_dirty(bh);
0211 }
0212
0213 struct inode *minix_new_inode(const struct inode *dir, umode_t mode, int *error)
0214 {
0215     struct super_block *sb = dir->i_sb;
0216     struct minix_sb_info *sbi = minix_sb(sb);
0217     struct inode *inode = new_inode(sb);
0218     struct buffer_head * bh;
0219     int bits_per_zone = 8 * sb->s_blocksize;
0220     unsigned long j;
0221     int i;
0222
0223     if (!inode) {
0224         *error = -ENOMEM;
0225         return NULL;
0226     }
0227     j = bits_per_zone;
0228     bh = NULL;
0229     *error = -ENOSPC;
0230     spin_lock(&bitmap_lock);
0231     for (i = 0; i < sbi->s_imap_blocks; i++) {
0232         bh = sbi->s_imap[i];
0233         j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
0234         if (j < bits_per_zone)
0235             break;
0236     }
0237     if (!bh || j >= bits_per_zone) {
0238         spin_unlock(&bitmap_lock);
0239         iput(inode);
0240         return NULL;
0241     }
0242     if (minix_test_and_set_bit(j, bh->b_data)) {    /* shouldn't happen */
0243         spin_unlock(&bitmap_lock);
0244         printk("minix_new_inode: bit already set\n");
0245         iput(inode);
0246         return NULL;
0247     }
0248     spin_unlock(&bitmap_lock);
0249     mark_buffer_dirty(bh);
0250     j += i * bits_per_zone;
0251     if (!j || j > sbi->s_ninodes) {
0252         iput(inode);
0253         return NULL;
0254     }
0255     inode_init_owner(&init_user_ns, inode, dir, mode);
0256     inode->i_ino = j;
0257     inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
0258     inode->i_blocks = 0;
0259     memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
0260     insert_inode_hash(inode);
0261     mark_inode_dirty(inode);
0262
0263     *error = 0;
0264     return inode;
0265 }
0266
0267 unsigned long minix_count_free_inodes(struct super_block *sb)
0268 {
0269     struct minix_sb_info *sbi = minix_sb(sb);
0270     u32 bits = sbi->s_ninodes + 1;
0271
0272     return count_free(sbi->s_imap, sb->s_blocksize, bits);
0273 }