Re: [PATCH 1/1 V2] mqueue: Implment generic xattr support

[Christoph Hellwig <hch@infradead.org>]

> +/*
> + * Callback for security_inode_init_security() for acquiring xattrs.
> + */
> +static int mqueue_initxattrs(struct inode *inode,
> +			    const struct xattr *xattr_array,
> +			    void *fs_info)
> +{
> +	struct mqueue_inode_info *info = MQUEUE_I(inode);
> +	const struct xattr *xattr;
> +	struct simple_xattr *new_xattr;
> +	size_t len;
> +
> +	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
> +		new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
> +		if (!new_xattr)
> +			return -ENOMEM;
> +		len = strlen(xattr->name) + 1;
> +		new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
> +					  GFP_KERNEL);
> +		if (!new_xattr->name) {
> +			kfree(new_xattr);
> +			return -ENOMEM;
> +		}
> +
> +		memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
> +		       XATTR_SECURITY_PREFIX_LEN);
> +		memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
> +		       xattr->name, len);
> +
> +		simple_xattr_list_add(&info->xattrs, new_xattr);
> +	}
> +
> +	return 0;
> +}

This is a 1:1 copy of the shmem code, we rally should consolidate it
into a single place first, as people will want it for whatever virtual
fs they care about sooner or later.