inode.c

linux平台下的systv文件系统源代码

					if (sb->sv_block_size>BLOCK_SIZE && (offsets[i] % 2))
						goto bad_shift;
					sb->sv_block_base = (offsets[i] << sb->sv_block_size_dec_bits) >> sb->sv_block_size_inc_bits;
					goto ok;
				}
				if ((found = detect_sysv2(sb,bh)) != NULL) {
					if (sb->sv_block_size>BLOCK_SIZE && (offsets[i] % 2))
						goto bad_shift;
					sb->sv_block_base = (offsets[i] << sb->sv_block_size_dec_bits) >> sb->sv_block_size_inc_bits;
					goto ok;
				}
				brelse(bh);
			}
	}
	bad_shift:
	if (!silent)
		printk("VFS: unable to read Xenix/SystemV/Coherent superblock on device "
		       "%s\n", kdevname(dev));
	failed:
	return NULL;

	ok:
	if (sb->sv_block_size >= BLOCK_SIZE) {
		if (sb->sv_block_size != BLOCK_SIZE) {
			brelse(bh);
			set_blocksize(dev, sb->sv_block_size);
			blocknr = (bh->b_blocknr << sb->sv_block_size_dec_bits) >> sb->sv_block_size_inc_bits;
			if ((bh = bread(dev, blocknr, sb->sv_block_size)) == NULL)
				goto bad_superblock;
		}
		switch (sb->sv_type) {
			case FSTYPE_XENIX:
				if (!detected_xenix(sb,bh,bh))
					goto bad_superblock;
				break;
			case FSTYPE_SYSV4:
				if (!detected_sysv4(sb,bh))
					goto bad_superblock;
				break;
			case FSTYPE_SYSV2:
				if (!detected_sysv2(sb,bh))
					goto bad_superblock;
				break;
			default: goto bad_superblock;
		goto superblock_ok;
		bad_superblock:
			brelse(bh);
			printk("SysV FS: cannot read superblock in %d byte mode\n", sb->sv_block_size);
			goto failed;
		superblock_ok:
		}
	} else {
		/* Switch to 512 block size. Unfortunately, we have to
		   release the block bh and read it again. */
		struct buffer_head *bh1, *bh2;
		unsigned long blocknr = (bh->b_blocknr << sb->sv_block_size_dec_bits) >> sb->sv_block_size_inc_bits;

		brelse(bh);
		set_blocksize(dev,sb->sv_block_size);
		bh1 = NULL; bh2 = NULL;
		switch (sb->sv_type) {
			case FSTYPE_XENIX:
				if ((bh1 = bread(dev, blocknr, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_xenix(sb,bh1,bh2))
					goto bad_superblock2;
				break;
			case FSTYPE_SYSV4:
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_sysv4(sb,bh2))
					goto bad_superblock2;
				break;
			case FSTYPE_SYSV2:
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_sysv2(sb,bh2))
					goto bad_superblock2;
				break;
			case FSTYPE_COH:
				if ((bh2 = bread(dev, blocknr+1, sb->sv_block_size)) == NULL)
					goto bad_superblock2;
				if (!detected_coherent(sb,bh2))
					goto bad_superblock2;
				break;
			default:
			bad_superblock2:
				brelse(bh1);
				brelse(bh2);
				set_blocksize(sb->s_dev,BLOCK_SIZE);
				printk("SysV FS: cannot read superblock in 512 byte mode\n");
				goto failed;
		}
	}
	sb->sv_ninodes = (sb->sv_firstdatazone - sb->sv_firstinodezone) << sb->sv_inodes_per_block_bits;
	if (!silent)
		printk("VFS: Found a %s FS (block size = %d) on device %s\n",
		       found, sb->sv_block_size, kdevname(dev));
	sb->s_magic = SYSV_MAGIC_BASE + sb->sv_type;
	/* The buffer code now supports block size 512 as well as 1024. */
	sb->s_blocksize = sb->sv_block_size;
	sb->s_blocksize_bits = sb->sv_block_size_bits;
	/* set up enough so that it can read an inode */
	sb->s_op = &sysv_sops;
	root_inode = iget(sb,SYSV_ROOT_INO);
	sb->s_root = d_alloc_root(root_inode);
	if (!sb->s_root) {
		printk("SysV FS: get root inode failed\n");
		sysv_put_super(sb);
		return NULL;
	}
#ifndef CONFIG_SYSV_FS_WRITE
	sb->s_flags |= MS_RDONLY;
#endif
	sb->s_dirt = 1;
	/* brelse(bh);  resp.  brelse(bh1); brelse(bh2);
	   occurs when the disk is unmounted. */
	return sb;
}

/* This is only called on sync() and umount(), when s_dirt=1. */
static void sysv_write_super(struct super_block *sb)
{
	if (buffer_dirty(sb->sv_bh1) || buffer_dirty(sb->sv_bh2)) {
		/* If we are going to write out the super block,
		   then attach current time stamp.
		   But if the filesystem was marked clean, keep it clean. */
		unsigned long time = CURRENT_TIME;
		unsigned long old_time = *sb->sv_sb_time;
		if (sb->sv_convert)
			old_time = from_coh_ulong(old_time);
		if (sb->sv_type == FSTYPE_SYSV4)
			if (*sb->sv_sb_state == 0x7c269d38 - old_time)
				*sb->sv_sb_state = 0x7c269d38 - time;
		if (sb->sv_convert)
			time = to_coh_ulong(time);
		*sb->sv_sb_time = time;
		mark_buffer_dirty(sb->sv_bh2);
	}
	sb->s_dirt = 0;
}

static void sysv_put_super(struct super_block *sb)
{
	/* we can assume sysv_write_super() has already been called,
	   and that the superblock is locked */
	brelse(sb->sv_bh1);
	if (sb->sv_bh1 != sb->sv_bh2) brelse(sb->sv_bh2);
	/* switch back to default block size */
	if (sb->s_blocksize != BLOCK_SIZE)
		set_blocksize(sb->s_dev,BLOCK_SIZE);
}

static int sysv_statfs(struct super_block *sb, struct statfs *buf)
{
	buf->f_type = sb->s_magic;			/* type of filesystem */
	buf->f_bsize = sb->sv_block_size;		/* block size */
	buf->f_blocks = sb->sv_ndatazones;		/* total data blocks in file system */
	buf->f_bfree = sysv_count_free_blocks(sb);	/* free blocks in fs */
	buf->f_bavail = buf->f_bfree;			/* free blocks available to non-superuser */
	buf->f_files = sb->sv_ninodes;			/* total file nodes in file system */
	buf->f_ffree = sysv_count_free_inodes(sb);	/* free file nodes in fs */
	buf->f_namelen = SYSV_NAMELEN;
	/* Don't know what value to put in buf->f_fsid */ /* file system id */
	return 0;
}


/* bmap support for running executables and shared libraries. */

static inline int inode_bmap(struct super_block * sb, struct inode * inode, int nr)
{
	int tmp = inode->u.sysv_i.i_data[nr];
	if (!tmp)
		return 0;
	return tmp + sb->sv_block_base;
}

static int block_bmap(struct super_block * sb, struct buffer_head * bh, int nr, int convert)
{
	int tmp;

	if (!bh)
		return 0;
	tmp = ((sysv_zone_t *) bh->b_data) [nr];
	if (convert)
		tmp = from_coh_ulong(tmp);
	brelse(bh);
	if (!tmp)
		return 0;
	return tmp + sb->sv_block_base;
}

static unsigned int sysv_block_map(struct inode *inode, unsigned int block)
{
	struct super_block *sb;
	int i, ret, convert;

	ret = 0;
	lock_kernel();
	sb = inode->i_sb;
	if (block < 10) {
		ret = inode_bmap(sb, inode, block);
		goto out;
	}
	block -= 10;
	convert = sb->sv_convert;
	if (block < sb->sv_ind_per_block) {
		i = inode_bmap(sb, inode, 10);
		if (!i)
			goto out;
		ret = block_bmap(sb,
				 bread(inode->i_dev, i, sb->sv_block_size),
				 block, convert);
		goto out;
	}
	block -= sb->sv_ind_per_block;
	if (block < sb->sv_ind_per_block_2) {
		i = inode_bmap(sb, inode, 11);
		if (!i)
			goto out;
		i = block_bmap(sb,
			       bread(inode->i_dev, i, sb->sv_block_size),
			       (block >> sb->sv_ind_per_block_bits), convert);
		if (!i)
			goto out;
		ret = block_bmap(sb,
				 bread(inode->i_dev, i, sb->sv_block_size),
				 (block & sb->sv_ind_per_block_1), convert);
		goto out;
	}
	block -= sb->sv_ind_per_block_2;
	if (block < sb->sv_ind_per_block_3) {
		i = inode_bmap(sb, inode, 12);
		if (!i)
			goto out;
		i = block_bmap(sb,
			       bread(inode->i_dev, i, sb->sv_block_size),
			       (block >> sb->sv_ind_per_block_2_bits), convert);
		if (!i)
			goto out;
		ret = block_bmap(sb,
				 bread(inode->i_dev, i, sb->sv_block_size),
				 ((block >> sb->sv_ind_per_block_bits) &
				  sb->sv_ind_per_block_1), convert);
		if (!i)
			goto out;
		ret = block_bmap(sb,
				 bread(inode->i_dev, i, sb->sv_block_size),
				 (block & sb->sv_ind_per_block_1), convert);
		goto out;
	}
	if ((int)block < 0)
		printk("sysv_block_map: block < 0\n");
	else
		printk("sysv_block_map: block > big\n");
out:
	unlock_kernel();
	return ret;
}

/* End of bmap support. */


/* Access selected blocks of regular files (or directories) */

static struct buffer_head *inode_getblk(struct inode *inode, int nr, int new_block,
	int *err, int metadata, long *phys, int *new)
{
	struct super_block *sb;
	u32 tmp;
	u32 *p;
	struct buffer_head * result;

	sb = inode->i_sb;
	p = inode->u.sysv_i.i_data + nr;
repeat:
	tmp = *p;
	if (tmp) {
		if (metadata) {
			result = sv_getblk(sb, inode->i_dev, tmp);
			if (tmp == *p)
				return result;
			brelse(result);
			goto repeat;
		} else {
			*phys = tmp;
			return NULL;
		}
	}

	tmp = sysv_new_block(sb);
	if (!tmp) {
		*err = -ENOSPC;
		return NULL;
	}
	if (metadata) {
		result = sv_getblk(sb, inode->i_dev, tmp);
		if (*p) {
			sysv_free_block(sb, tmp);
			brelse(result);
			goto repeat;
		}
	} else {
		if (*p) {
			/*
			 * Nobody is allowed to change block allocation
			 * state from under us:
			 */
			BUG();
			sysv_free_block(sb, tmp);
			goto repeat;
		}
		*phys = tmp;
		result = NULL;
		*err = 0;
		*new = 1;
	}
	*p = tmp;

	inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty(inode);
	return result;
}

static struct buffer_head *block_getblk(struct inode *inode,
	struct buffer_head *bh, int nr, int new_block, int *err,
	int metadata, long *phys, int *new)
{
	struct super_block *sb;
	u32 tmp, block;
	sysv_zone_t *p;
	struct buffer_head * result;

	result = NULL;
	if (!bh)
		goto out;
	if (!buffer_uptodate(bh)) {
		ll_rw_block(READ, 1, &bh);
		wait_on_buffer(bh);
		if (!buffer_uptodate(bh))
			goto out;
	}
	sb = inode->i_sb;
	p = nr + (sysv_zone_t *) bh->b_data;
repeat:
	block = tmp = *p;
	if (sb->sv_convert)
		block = from_coh_ulong(block);
	if (tmp) {
		if (metadata) {
			result = sv_getblk(sb, bh->b_dev, block);
			if (tmp == *p)
				goto out;
			brelse(result);
			goto repeat;
		} else {
			*phys = tmp;
			goto out;
		}
	}

	block = sysv_new_block(sb);
	if (!block)
		goto out;
	if (metadata) {
		result = sv_getblk(sb, bh->b_dev, block);
		if (*p) {
			sysv_free_block(sb, block);
			brelse(result);
			goto repeat;
		}
		memset(result->b_data, 0, sb->sv_block_size);
		mark_buffer_uptodate(result, 1);
		mark_buffer_dirty(result);
	} else {
		*phys = tmp;
		*new = 1;
	}
	if (*p) {
		sysv_free_block(sb, block);
		brelse(result);
		goto repeat;
	}
	*p = (sb->sv_convert ? to_coh_ulong(block) : block);
	mark_buffer_dirty(bh);
	*err = 0;
out:
	brelse(bh);
	return result;
}

static int sysv_get_block(struct inode *inode, long iblock, struct buffer_head *bh_result, int create)