diff options
Diffstat (limited to 'fs/sysv/balloc.c')
| -rw-r--r-- | fs/sysv/balloc.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/fs/sysv/balloc.c b/fs/sysv/balloc.c new file mode 100644 index 0000000..9a6ad96a --- /dev/null +++ b/fs/sysv/balloc.c @@ -0,0 +1,239 @@ +/* + * linux/fs/sysv/balloc.c + * + * minix/bitmap.c + * Copyright (C) 1991, 1992 Linus Torvalds + * + * ext/freelists.c + * Copyright (C) 1992 Remy Card (card@masi.ibp.fr) + * + * xenix/alloc.c + * Copyright (C) 1992 Doug Evans + * + * coh/alloc.c + * Copyright (C) 1993 Pascal Haible, Bruno Haible + * + * sysv/balloc.c + * Copyright (C) 1993 Bruno Haible + * + * This file contains code for allocating/freeing blocks. + */ + +#include <linux/buffer_head.h> +#include <linux/string.h> +#include "sysv.h" + +/* We don't trust the value of + sb->sv_sbd2->s_tfree = *sb->sv_free_blocks + but we nevertheless keep it up to date. */ + +static inline sysv_zone_t *get_chunk(struct super_block *sb, struct buffer_head *bh) +{ + char *bh_data = bh->b_data; + + if (SYSV_SB(sb)->s_type == FSTYPE_SYSV4) + return (sysv_zone_t*)(bh_data+4); + else + return (sysv_zone_t*)(bh_data+2); +} + +/* NOTE NOTE NOTE: nr is a block number _as_ _stored_ _on_ _disk_ */ + +void sysv_free_block(struct super_block * sb, sysv_zone_t nr) +{ + struct sysv_sb_info * sbi = SYSV_SB(sb); + struct buffer_head * bh; + sysv_zone_t *blocks = sbi->s_bcache; + unsigned count; + unsigned block = fs32_to_cpu(sbi, nr); + + /* + * This code does not work at all for AFS (it has a bitmap + * free list). As AFS is supposed to be read-only no one + * should call this for an AFS filesystem anyway... + */ + if (sbi->s_type == FSTYPE_AFS) + return; + + if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) { + printk("sysv_free_block: trying to free block not in datazone\n"); + return; + } + + lock_super(sb); + count = fs16_to_cpu(sbi, *sbi->s_bcache_count); + + if (count > sbi->s_flc_size) { + printk("sysv_free_block: flc_count > flc_size\n"); + unlock_super(sb); + return; + } + /* If the free list head in super-block is full, it is copied + * into this block being freed, ditto if it's completely empty + * (applies only on Coherent). + */ + if (count == sbi->s_flc_size || count == 0) { + block += sbi->s_block_base; + bh = sb_getblk(sb, block); + if (!bh) { + printk("sysv_free_block: getblk() failed\n"); + unlock_super(sb); + return; + } + memset(bh->b_data, 0, sb->s_blocksize); + *(__fs16*)bh->b_data = cpu_to_fs16(sbi, count); + memcpy(get_chunk(sb,bh), blocks, count * sizeof(sysv_zone_t)); + mark_buffer_dirty(bh); + set_buffer_uptodate(bh); + brelse(bh); + count = 0; + } + sbi->s_bcache[count++] = nr; + + *sbi->s_bcache_count = cpu_to_fs16(sbi, count); + fs32_add(sbi, sbi->s_free_blocks, 1); + dirty_sb(sb); + unlock_super(sb); +} + +sysv_zone_t sysv_new_block(struct super_block * sb) +{ + struct sysv_sb_info *sbi = SYSV_SB(sb); + unsigned int block; + sysv_zone_t nr; + struct buffer_head * bh; + unsigned count; + + lock_super(sb); + count = fs16_to_cpu(sbi, *sbi->s_bcache_count); + + if (count == 0) /* Applies only to Coherent FS */ + goto Enospc; + nr = sbi->s_bcache[--count]; + if (nr == 0) /* Applies only to Xenix FS, SystemV FS */ + goto Enospc; + + block = fs32_to_cpu(sbi, nr); + + *sbi->s_bcache_count = cpu_to_fs16(sbi, count); + + if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) { + printk("sysv_new_block: new block %d is not in data zone\n", + block); + goto Enospc; + } + + if (count == 0) { /* the last block continues the free list */ + unsigned count; + + block += sbi->s_block_base; + if (!(bh = sb_bread(sb, block))) { + printk("sysv_new_block: cannot read free-list block\n"); + /* retry this same block next time */ + *sbi->s_bcache_count = cpu_to_fs16(sbi, 1); + goto Enospc; + } + count = fs16_to_cpu(sbi, *(__fs16*)bh->b_data); + if (count > sbi->s_flc_size) { + printk("sysv_new_block: free-list block with >flc_size entries\n"); + brelse(bh); + goto Enospc; + } + *sbi->s_bcache_count = cpu_to_fs16(sbi, count); + memcpy(sbi->s_bcache, get_chunk(sb, bh), + count * sizeof(sysv_zone_t)); + brelse(bh); + } + /* Now the free list head in the superblock is valid again. */ + fs32_add(sbi, sbi->s_free_blocks, -1); + dirty_sb(sb); + unlock_super(sb); + return nr; + +Enospc: + unlock_super(sb); + return 0; +} + +unsigned long sysv_count_free_blocks(struct super_block * sb) +{ + struct sysv_sb_info * sbi = SYSV_SB(sb); + int sb_count; + int count; + struct buffer_head * bh = NULL; + sysv_zone_t *blocks; + unsigned block; + int n; + + /* + * This code does not work at all for AFS (it has a bitmap + * free list). As AFS is supposed to be read-only we just + * lie and say it has no free block at all. + */ + if (sbi->s_type == FSTYPE_AFS) + return 0; + + lock_super(sb); + sb_count = fs32_to_cpu(sbi, *sbi->s_free_blocks); + + if (0) + goto trust_sb; + + /* this causes a lot of disk traffic ... */ + count = 0; + n = fs16_to_cpu(sbi, *sbi->s_bcache_count); + blocks = sbi->s_bcache; + while (1) { + sysv_zone_t zone; + if (n > sbi->s_flc_size) + goto E2big; + zone = 0; + while (n && (zone = blocks[--n]) != 0) + count++; + if (zone == 0) + break; + + block = fs32_to_cpu(sbi, zone); + if (bh) + brelse(bh); + + if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) + goto Einval; + block += sbi->s_block_base; + bh = sb_bread(sb, block); + if (!bh) + goto Eio; + n = fs16_to_cpu(sbi, *(__fs16*)bh->b_data); + blocks = get_chunk(sb, bh); + } + if (bh) + brelse(bh); + if (count != sb_count) + goto Ecount; +done: + unlock_super(sb); + return count; + +Einval: + printk("sysv_count_free_blocks: new block %d is not in data zone\n", + block); + goto trust_sb; +Eio: + printk("sysv_count_free_blocks: cannot read free-list block\n"); + goto trust_sb; +E2big: + printk("sysv_count_free_blocks: >flc_size entries in free-list block\n"); + if (bh) + brelse(bh); +trust_sb: + count = sb_count; + goto done; +Ecount: + printk("sysv_count_free_blocks: free block count was %d, " + "correcting to %d\n", sb_count, count); + if (!(sb->s_flags & MS_RDONLY)) { + *sbi->s_free_blocks = cpu_to_fs32(sbi, count); + dirty_sb(sb); + } + goto done; +} |
