dir.c

linux 内核源代码

	const char *name = de->d_name.name;
	int len = de->d_name.len;

	lock_kernel();

	error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
	if ( error ) {
		unlock_kernel();
		return error;
	}

	coda_dir_update_mtime(dir);
	drop_nlink(de->d_inode);
	unlock_kernel();
	return 0;
}

int coda_rmdir(struct inode *dir, struct dentry *de)
{
	const char *name = de->d_name.name;
	int len = de->d_name.len;
	int error;

	lock_kernel();

	error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
	if (!error) {
		/* VFS may delete the child */
		if (de->d_inode)
		    de->d_inode->i_nlink = 0;

		/* fix the link count of the parent */
		coda_dir_drop_nlink(dir);
		coda_dir_update_mtime(dir);
	}
	unlock_kernel();
	return error;
}

/* rename */
static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
		       struct inode *new_dir, struct dentry *new_dentry)
{
	const char *old_name = old_dentry->d_name.name;
	const char *new_name = new_dentry->d_name.name;
	int old_length = old_dentry->d_name.len;
	int new_length = new_dentry->d_name.len;
	int error;

	lock_kernel();

	error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
			     coda_i2f(new_dir), old_length, new_length,
			     (const char *) old_name, (const char *)new_name);

	if ( !error ) {
		if ( new_dentry->d_inode ) {
			if ( S_ISDIR(new_dentry->d_inode->i_mode) ) {
				coda_dir_drop_nlink(old_dir);
				coda_dir_inc_nlink(new_dir);
			}
			coda_dir_update_mtime(old_dir);
			coda_dir_update_mtime(new_dir);
			coda_flag_inode(new_dentry->d_inode, C_VATTR);
		} else {
			coda_flag_inode(old_dir, C_VATTR);
			coda_flag_inode(new_dir, C_VATTR);
		}
	}
	unlock_kernel();

	return error;
}


/* file operations for directories */
int coda_readdir(struct file *coda_file, void *buf, filldir_t filldir)
{
	struct coda_file_info *cfi;
	struct file *host_file;
	int ret;

	cfi = CODA_FTOC(coda_file);
	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
	host_file = cfi->cfi_container;

	if (!host_file->f_op)
		return -ENOTDIR;

	if (host_file->f_op->readdir)
	{
		/* potemkin case: we were handed a directory inode.
		 * We can't use vfs_readdir because we have to keep the file
		 * position in sync between the coda_file and the host_file.
		 * and as such we need grab the inode mutex. */
		struct inode *host_inode = host_file->f_path.dentry->d_inode;

		mutex_lock(&host_inode->i_mutex);
		host_file->f_pos = coda_file->f_pos;

		ret = -ENOENT;
		if (!IS_DEADDIR(host_inode)) {
			ret = host_file->f_op->readdir(host_file, buf, filldir);
			file_accessed(host_file);
		}

		coda_file->f_pos = host_file->f_pos;
		mutex_unlock(&host_inode->i_mutex);
	}
	else /* Venus: we must read Venus dirents from a file */
		ret = coda_venus_readdir(coda_file, buf, filldir);

	return ret;
}

static inline unsigned int CDT2DT(unsigned char cdt)
{
	unsigned int dt;

	switch(cdt) {
	case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
	case CDT_FIFO:	  dt = DT_FIFO;    break;
	case CDT_CHR:	  dt = DT_CHR;     break;
	case CDT_DIR:	  dt = DT_DIR;     break;
	case CDT_BLK:	  dt = DT_BLK;     break;
	case CDT_REG:	  dt = DT_REG;     break;
	case CDT_LNK:	  dt = DT_LNK;     break;
	case CDT_SOCK:	  dt = DT_SOCK;    break;
	case CDT_WHT:	  dt = DT_WHT;     break;
	default:	  dt = DT_UNKNOWN; break;
	}
	return dt;
}

/* support routines */
static int coda_venus_readdir(struct file *coda_file, void *buf,
			      filldir_t filldir)
{
	int result = 0; /* # of entries returned */
	struct coda_file_info *cfi;
	struct coda_inode_info *cii;
	struct file *host_file;
	struct dentry *de;
	struct venus_dirent *vdir;
	unsigned long vdir_size =
	    (unsigned long)(&((struct venus_dirent *)0)->d_name);
	unsigned int type;
	struct qstr name;
	ino_t ino;
	int ret;

	cfi = CODA_FTOC(coda_file);
	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
	host_file = cfi->cfi_container;

	de = coda_file->f_path.dentry;
	cii = ITOC(de->d_inode);

	vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
	if (!vdir) return -ENOMEM;

	if (coda_file->f_pos == 0) {
		ret = filldir(buf, ".", 1, 0, de->d_inode->i_ino, DT_DIR);
		if (ret < 0)
			goto out;
		result++;
		coda_file->f_pos++;
	}
	if (coda_file->f_pos == 1) {
		ret = filldir(buf, "..", 2, 1, de->d_parent->d_inode->i_ino, DT_DIR);
		if (ret < 0)
			goto out;
		result++;
		coda_file->f_pos++;
	}
	while (1) {
		/* read entries from the directory file */
		ret = kernel_read(host_file, coda_file->f_pos - 2, (char *)vdir,
				  sizeof(*vdir));
		if (ret < 0) {
			printk(KERN_ERR "coda readdir: read dir %s failed %d\n",
			       coda_f2s(&cii->c_fid), ret);
			break;
		}
		if (ret == 0) break; /* end of directory file reached */

		/* catch truncated reads */
		if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
			printk(KERN_ERR "coda readdir: short read on %s\n",
			       coda_f2s(&cii->c_fid));
			ret = -EBADF;
			break;
		}
		/* validate whether the directory file actually makes sense */
		if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
			printk(KERN_ERR "coda readdir: invalid dir %s\n",
			       coda_f2s(&cii->c_fid));
			ret = -EBADF;
			break;
		}

		name.len = vdir->d_namlen;
		name.name = vdir->d_name;

		/* Make sure we skip '.' and '..', we already got those */
		if (name.name[0] == '.' && (name.len == 1 ||
		    (vdir->d_name[1] == '.' && name.len == 2)))
			vdir->d_fileno = name.len = 0;

		/* skip null entries */
		if (vdir->d_fileno && name.len) {
			/* try to look up this entry in the dcache, that way
			 * userspace doesn't have to worry about breaking
			 * getcwd by having mismatched inode numbers for
			 * internal volume mountpoints. */
			ino = find_inode_number(de, &name);
			if (!ino) ino = vdir->d_fileno;

			type = CDT2DT(vdir->d_type);
			ret = filldir(buf, name.name, name.len,
				      coda_file->f_pos, ino, type);
			/* failure means no space for filling in this round */
			if (ret < 0) break;
			result++;
		}
		/* we'll always have progress because d_reclen is unsigned and
		 * we've already established it is non-zero. */
		coda_file->f_pos += vdir->d_reclen;
	}
out:
	kfree(vdir);
	return result ? result : ret;
}

/* called when a cache lookup succeeds */
static int coda_dentry_revalidate(struct dentry *de, struct nameidata *nd)
{
	struct inode *inode = de->d_inode;
	struct coda_inode_info *cii;

	if (!inode)
		return 1;
	lock_kernel();
	if (coda_isroot(inode))
		goto out;
	if (is_bad_inode(inode))
		goto bad;

	cii = ITOC(de->d_inode);
	if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
		goto out;

	shrink_dcache_parent(de);

	/* propagate for a flush */
	if (cii->c_flags & C_FLUSH) 
		coda_flag_inode_children(inode, C_FLUSH);

	if (atomic_read(&de->d_count) > 1)
		/* pretend it's valid, but don't change the flags */
		goto out;

	/* clear the flags. */
	cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);

bad:
	unlock_kernel();
	return 0;
out:
	unlock_kernel();
	return 1;
}

/*
 * This is the callback from dput() when d_count is going to 0.
 * We use this to unhash dentries with bad inodes.
 */
static int coda_dentry_delete(struct dentry * dentry)
{
	int flags;

	if (!dentry->d_inode) 
		return 0;

	flags = (ITOC(dentry->d_inode)->c_flags) & C_PURGE;
	if (is_bad_inode(dentry->d_inode) || flags) {
		return 1;
	}
	return 0;
}



/*
 * This is called when we want to check if the inode has
 * changed on the server.  Coda makes this easy since the
 * cache manager Venus issues a downcall to the kernel when this 
 * happens 
 */
int coda_revalidate_inode(struct dentry *dentry)
{
	struct coda_vattr attr;
	int error = 0;
	int old_mode;
	ino_t old_ino;
	struct inode *inode = dentry->d_inode;
	struct coda_inode_info *cii = ITOC(inode);

	lock_kernel();
	if ( !cii->c_flags )
		goto ok;

	if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
		error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
		if ( error )
			goto return_bad;

		/* this inode may be lost if:
		   - it's ino changed 
		   - type changes must be permitted for repair and
		   missing mount points.
		*/
		old_mode = inode->i_mode;
		old_ino = inode->i_ino;
		coda_vattr_to_iattr(inode, &attr);

		if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
			printk("Coda: inode %ld, fid %s changed type!\n",
			       inode->i_ino, coda_f2s(&(cii->c_fid)));
		}

		/* the following can happen when a local fid is replaced 
		   with a global one, here we lose and declare the inode bad */
		if (inode->i_ino != old_ino)
			goto return_bad;
		
		coda_flag_inode_children(inode, C_FLUSH);
		cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
	}

ok:
	unlock_kernel();
	return 0;

return_bad:
	unlock_kernel();
	return -EIO;
}