inode.c

linux平台下的systv文件系统源代码

{
	struct super_block *sb;
	int ret, err, new;
	struct buffer_head *bh;
	unsigned long ptr, phys;

	if (!create) {
		phys = sysv_block_map(inode, iblock);
		if (phys) {
			bh_result->b_dev = inode->i_dev;
			bh_result->b_blocknr = phys;
			bh_result->b_state |= (1UL << BH_Mapped);
		}
		return 0;
	}

	err = -EIO;
	new = 0;
	ret = 0;
	bh = NULL;

	lock_kernel();
	sb = inode->i_sb;
	if (iblock < 0)
		goto abort_negative;
	if (iblock > sb->sv_ind_per_block_3)
		goto abort_too_big;

	err = 0;
	ptr = iblock;

	/*
	 * ok, these macros clean the logic up a bit and make
	 * it much more readable:
	 */
#define GET_INODE_DATABLOCK(x) \
		inode_getblk(inode, x, iblock, &err, 0, &phys, &new)
#define GET_INODE_PTR(x) \
		inode_getblk(inode, x, iblock, &err, 1, NULL, NULL)
#define GET_INDIRECT_DATABLOCK(x) \
		block_getblk (inode, bh, x, iblock, &err, 0, &phys, &new);
#define GET_INDIRECT_PTR(x) \
		block_getblk (inode, bh, x, iblock, &err, 1, NULL, NULL);

	if (ptr < 10) {
		bh = GET_INODE_DATABLOCK(ptr);
		goto out;
	}
	ptr -= 10;
	if (ptr < sb->sv_ind_per_block) {
		bh = GET_INODE_PTR(10);
		goto get_indirect;
	}
	ptr -= sb->sv_ind_per_block;
	if (ptr < sb->sv_ind_per_block_2) {
		bh = GET_INODE_PTR(11);
		goto get_double;
	}
	ptr -= sb->sv_ind_per_block_2;
	bh = GET_INODE_PTR(12);
	bh = GET_INDIRECT_PTR(ptr >> sb->sv_ind_per_block_2_bits);
get_double:
	bh = GET_INDIRECT_PTR((ptr >> sb->sv_ind_per_block_bits) & sb->sv_ind_per_block_1);
get_indirect:
	bh = GET_INDIRECT_DATABLOCK(ptr & sb->sv_ind_per_block_1);

#undef GET_INODE_DATABLOCK
#undef GET_INODE_PTR
#undef GET_INDIRECT_DATABLOCK
#undef GET_INDIRECT_PTR

out:
	if (err)
		goto abort;
	bh_result->b_dev = inode->i_dev;
	bh_result->b_blocknr = phys;
	bh_result->b_state |= (1UL << BH_Mapped);
	if (new)
		bh_result->b_state |= (1UL << BH_New);
abort:
	unlock_kernel();
	return err;

abort_negative:
	printk("sysv_get_block: block < 0\n");
	goto abort;

abort_too_big:
	printk("sysv_get_block: block > big\n");
	goto abort;
}

static struct buffer_head *sysv_getblk(struct inode *inode, unsigned int block, int create)
{
	struct buffer_head dummy;
	int error;

	dummy.b_state = 0;
	dummy.b_blocknr = -1000;
	error = sysv_get_block(inode, block, &dummy, create);
	if (!error && buffer_mapped(&dummy)) {
		struct buffer_head *bh;
		bh = getblk(dummy.b_dev, dummy.b_blocknr, inode->i_sb->sv_block_size);
		if (buffer_new(&dummy)) {
			memset(bh->b_data, 0, inode->i_sb->sv_block_size);
			mark_buffer_uptodate(bh, 1);
			mark_buffer_dirty(bh);
		}
		return bh;
	}
	return NULL;
}

struct buffer_head *sysv_file_bread(struct inode *inode, int block, int create)
{
	struct buffer_head *bh;

	bh = sysv_getblk(inode, block, create);
	if (!bh || buffer_uptodate(bh))
		return bh;
	ll_rw_block(READ, 1, &bh);
	wait_on_buffer(bh);
	if (buffer_uptodate(bh))
		return bh;
	brelse(bh);
	return NULL;
}

static int sysv_writepage(struct page *page)
{
	return block_write_full_page(page,sysv_get_block);
}
static int sysv_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page,sysv_get_block);
}
static int sysv_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
	return block_prepare_write(page,from,to,sysv_get_block);
}
static int sysv_bmap(struct address_space *mapping, long block)
{
	return generic_block_bmap(mapping,block,sysv_get_block);
}
struct address_space_operations sysv_aops = {
	readpage: sysv_readpage,
	writepage: sysv_writepage,
	sync_page: block_sync_page,
	prepare_write: sysv_prepare_write,
	commit_write: generic_commit_write,
	bmap: sysv_bmap
};

#ifdef __BIG_ENDIAN

static inline unsigned long read3byte (unsigned char * p)
{
	return (p[2] | (p[1]<<8) | (p[0]<<16));
}

static inline void write3byte (unsigned char *p , unsigned long val)
{
	p[2]=val&0xFF;
	p[1]=(val>>8)&0xFF;
	p[0]=(val>>16)&0xFF;
}

#else

static inline unsigned long read3byte (unsigned char * p)
{
	return (unsigned long)(*(unsigned short *)p)
	     | (unsigned long)(*(unsigned char *)(p+2)) << 16;
}

static inline void write3byte (unsigned char * p, unsigned long val)
{
	*(unsigned short *)p = (unsigned short) val;
	*(unsigned char *)(p+2) = val >> 16;
}

#endif

static inline unsigned long coh_read3byte (unsigned char * p)
{
	return (unsigned long)(*(unsigned char *)p) << 16
	     | (unsigned long)(*(unsigned short *)(p+1));
}

static inline void coh_write3byte (unsigned char * p, unsigned long val)
{
	*(unsigned char *)p = val >> 16;
	*(unsigned short *)(p+1) = (unsigned short) val;
}

struct inode_operations sysv_symlink_inode_operations = {
	readlink:	page_readlink,
	follow_link:	page_follow_link,
	setattr:	sysv_notify_change,
};

static void sysv_read_inode(struct inode *inode)
{
	struct super_block * sb = inode->i_sb;
	struct buffer_head * bh;
	struct sysv_inode * raw_inode;
	unsigned int block, ino;
	umode_t mode;

	ino = inode->i_ino;
	inode->i_mode = 0;
	if (!ino || ino > sb->sv_ninodes) {
		printk("Bad inode number on dev %s"
		       ": %d is out of range\n",
		       kdevname(inode->i_dev), ino);
		return;
	}
	block = sb->sv_firstinodezone + ((ino-1) >> sb->sv_inodes_per_block_bits);
	if (!(bh = sv_bread(sb,inode->i_dev,block))) {
		printk("Major problem: unable to read inode from dev "
		       "%s\n",
		       kdevname(inode->i_dev));
		return;
	}
	raw_inode = (struct sysv_inode *) bh->b_data + ((ino-1) & sb->sv_inodes_per_block_1);
	mode = raw_inode->i_mode;
	if (sb->sv_kludge_symlinks)
		mode = from_coh_imode(mode);
	/* SystemV FS: kludge permissions if ino==SYSV_ROOT_INO ?? */
	inode->i_mode = mode;
	inode->i_uid = (uid_t)raw_inode->i_uid;
	inode->i_gid = (gid_t)raw_inode->i_gid;
	inode->i_nlink = raw_inode->i_nlink;
	if (sb->sv_convert) {
		inode->i_size = from_coh_ulong(raw_inode->i_size);
		inode->i_atime = from_coh_ulong(raw_inode->i_atime);
		inode->i_mtime = from_coh_ulong(raw_inode->i_mtime);
		inode->i_ctime = from_coh_ulong(raw_inode->i_ctime);
	} else {
		inode->i_size = raw_inode->i_size;
		inode->i_atime = raw_inode->i_atime;
		inode->i_mtime = raw_inode->i_mtime;
		inode->i_ctime = raw_inode->i_ctime;
	}
	inode->i_blocks = inode->i_blksize = 0;
	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
		;
	else
	if (sb->sv_convert)
		for (block = 0; block < 10+1+1+1; block++)
			inode->u.sysv_i.i_data[block] =
				coh_read3byte(&raw_inode->i_a.i_addb[3*block]);
	else
		for (block = 0; block < 10+1+1+1; block++)
			inode->u.sysv_i.i_data[block] =
				read3byte(&raw_inode->i_a.i_addb[3*block]);
	if (S_ISREG(inode->i_mode)) {
		inode->i_op = &sysv_file_inode_operations;
		inode->i_fop = &sysv_file_operations;
		inode->i_mapping->a_ops = &sysv_aops;
	} else if (S_ISDIR(inode->i_mode)) {
		inode->i_op = &sysv_dir_inode_operations;
		inode->i_fop = &sysv_dir_operations;
	} else if (S_ISLNK(inode->i_mode)) {
		inode->i_op = &sysv_symlink_inode_operations;
		inode->i_mapping->a_ops = &sysv_aops;
	} else
		init_special_inode(inode, inode->i_mode,raw_inode->i_a.i_rdev);
	brelse(bh);
}

/* To avoid inconsistencies between inodes in memory and inodes on disk. */
int sysv_notify_change(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;
	int error;

	if ((error = inode_change_ok(inode, attr)) != 0)
		return error;

	if (attr->ia_valid & ATTR_MODE)
		if (inode->i_sb->sv_kludge_symlinks)
			if (attr->ia_mode == COH_KLUDGE_SYMLINK_MODE)
				attr->ia_mode = COH_KLUDGE_NOT_SYMLINK;

	inode_setattr(inode, attr);

	return 0;
}

static struct buffer_head * sysv_update_inode(struct inode * inode)
{
	struct super_block * sb = inode->i_sb;
	struct buffer_head * bh;
	struct sysv_inode * raw_inode;
	unsigned int ino, block;
	umode_t mode;

	ino = inode->i_ino;
	if (!ino || ino > sb->sv_ninodes) {
		printk("Bad inode number on dev %s"
		       ": %d is out of range\n",
		       kdevname(inode->i_dev), ino);
		return 0;
	}
	block = sb->sv_firstinodezone + ((ino-1) >> sb->sv_inodes_per_block_bits);
	if (!(bh = sv_bread(sb,inode->i_dev,block))) {
		printk("unable to read i-node block\n");
		return 0;
	}
	raw_inode = (struct sysv_inode *) bh->b_data + ((ino-1) & sb->sv_inodes_per_block_1);
	mode = inode->i_mode;
	if (sb->sv_kludge_symlinks)
		mode = to_coh_imode(mode);
	raw_inode->i_mode = mode;
	raw_inode->i_uid = fs_high2lowuid(inode->i_uid);
	raw_inode->i_gid = fs_high2lowgid(inode->i_gid);
	raw_inode->i_nlink = inode->i_nlink;
	if (sb->sv_convert) {
		raw_inode->i_size = to_coh_ulong(inode->i_size);
		raw_inode->i_atime = to_coh_ulong(inode->i_atime);
		raw_inode->i_mtime = to_coh_ulong(inode->i_mtime);
		raw_inode->i_ctime = to_coh_ulong(inode->i_ctime);
	} else {
		raw_inode->i_size = inode->i_size;
		raw_inode->i_atime = inode->i_atime;
		raw_inode->i_mtime = inode->i_mtime;
		raw_inode->i_ctime = inode->i_ctime;
	}
	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
		raw_inode->i_a.i_rdev = kdev_t_to_nr(inode->i_rdev); /* write 2 or 3 bytes ?? */
	else
	if (sb->sv_convert)
		for (block = 0; block < 10+1+1+1; block++)
			coh_write3byte(&raw_inode->i_a.i_addb[3*block],inode->u.sysv_i.i_data[block]);
	else
		for (block = 0; block < 10+1+1+1; block++)
			write3byte(&raw_inode->i_a.i_addb[3*block],inode->u.sysv_i.i_data[block]);
	mark_buffer_dirty(bh);
	return bh;
}

void sysv_write_inode(struct inode * inode, int wait)
{
	struct buffer_head *bh;
	lock_kernel();
	bh = sysv_update_inode(inode);
	brelse(bh);
	unlock_kernel();
}

int sysv_sync_inode(struct inode * inode)
{
        int err = 0;
        struct buffer_head *bh;

        bh = sysv_update_inode(inode);
        if (bh && buffer_dirty(bh)) {
                ll_rw_block(WRITE, 1, &bh);
                wait_on_buffer(bh);
                if (buffer_req(bh) && !buffer_uptodate(bh))
                {
                        printk ("IO error syncing sysv inode ["
				"%s:%08lx]\n",
                                kdevname(inode->i_dev), inode->i_ino);
                        err = -1;
                }
        }
        else if (!bh)
                err = -1;
        brelse (bh);
        return err;
}

/* Every kernel module contains stuff like this. */

static DECLARE_FSTYPE_DEV(sysv_fs_type, "sysv", sysv_read_super);

static int __init init_sysv_fs(void)
{
	return register_filesystem(&sysv_fs_type);
}

static void __exit exit_sysv_fs(void)
{
	unregister_filesystem(&sysv_fs_type);
}

EXPORT_NO_SYMBOLS;

module_init(init_sysv_fs)
module_exit(exit_sysv_fs)