Re: [PATCH v2 05/15] xfs: mount-api - make xfs_parse_param() take context .parse_param() args

[Brian Foster <bfoster@redhat.com>]

On Fri, Aug 23, 2019 at 08:59:43AM +0800, Ian Kent wrote:
> Make xfs_parse_param() take arguments of the fs context operation
> .parse_param() in preperation for switching to use the file system
> mount context for mount.
> 
> The function fc_parse() only uses the file system context (fc here)
> when calling log macros warnf() and invalf() which in turn check
> only the fc->log field to determine if the message should be saved
> to a context buffer (for later retrival by userspace) or logged
> using printk().
> 
> Also the temporary function match_kstrtoint() is now unused, remove it.
> 
> Signed-off-by: Ian Kent <raven@themaw.net>
> ---

I see Eric had some feedback on this patch already. Some additional
notes (which may overlap)...

>  fs/xfs/xfs_super.c |  187 ++++++++++++++++++++++++++++++----------------------
>  1 file changed, 108 insertions(+), 79 deletions(-)
> 
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 3ae29938dd89..754d2ccfd960 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
...
> @@ -275,33 +271,38 @@ xfs_parse_param(
>  		mp->m_flags |= XFS_MOUNT_NOUUID;
>  		break;
>  	case Opt_ikeep:
> -		mp->m_flags |= XFS_MOUNT_IKEEP;
> -		break;
> -	case Opt_noikeep:
> -		mp->m_flags &= ~XFS_MOUNT_IKEEP;
> +		if (result.negated)
> +			mp->m_flags &= ~XFS_MOUNT_IKEEP;
> +		else
> +			mp->m_flags |= XFS_MOUNT_IKEEP;
>  		break;
>  	case Opt_largeio:
> -		mp->m_flags &= ~XFS_MOUNT_COMPAT_IOSIZE;
> -		break;
> -	case Opt_nolargeio:
> -		mp->m_flags |= XFS_MOUNT_COMPAT_IOSIZE;
> +		if (result.negated)
> +			mp->m_flags |= XFS_MOUNT_COMPAT_IOSIZE;
> +		else
> +			mp->m_flags &= ~XFS_MOUNT_COMPAT_IOSIZE;
>  		break;
>  	case Opt_attr2:
> -		mp->m_flags |= XFS_MOUNT_ATTR2;
> -		break;
> -	case Opt_noattr2:
> -		mp->m_flags &= ~XFS_MOUNT_ATTR2;
> -		mp->m_flags |= XFS_MOUNT_NOATTR2;
> +		if (!result.negated) {
> +			mp->m_flags |= XFS_MOUNT_ATTR2;
> +		} else {
> +			mp->m_flags &= ~XFS_MOUNT_ATTR2;
> +			mp->m_flags |= XFS_MOUNT_NOATTR2;
> +		}

Eric's comments aside, it would be nice to have some consistency between
the various result.negated checks (i.e. 'if (negated)' vs 'if
(!negated)').

>  		break;
>  	case Opt_filestreams:
>  		mp->m_flags |= XFS_MOUNT_FILESTREAMS;
>  		break;
> -	case Opt_noquota:
> -		mp->m_qflags &= ~XFS_ALL_QUOTA_ACCT;
> -		mp->m_qflags &= ~XFS_ALL_QUOTA_ENFD;
> -		mp->m_qflags &= ~XFS_ALL_QUOTA_ACTIVE;
> -		break;
>  	case Opt_quota:
> +		if (!result.negated) {
> +			mp->m_qflags |= (XFS_UQUOTA_ACCT | XFS_UQUOTA_ACTIVE |
> +					 XFS_UQUOTA_ENFD);
> +		} else {
> +			mp->m_qflags &= ~XFS_ALL_QUOTA_ACCT;
> +			mp->m_qflags &= ~XFS_ALL_QUOTA_ENFD;
> +			mp->m_qflags &= ~XFS_ALL_QUOTA_ACTIVE;
> +		}
> +		break;
>  	case Opt_uquota:
>  	case Opt_usrquota:
>  		mp->m_qflags |= (XFS_UQUOTA_ACCT | XFS_UQUOTA_ACTIVE |
...
> @@ -367,10 +368,10 @@ xfs_parseargs(
>  {
>  	const struct super_block *sb = mp->m_super;
>  	char			*p;
> -	substring_t		args[MAX_OPT_ARGS];
> -	int			dsunit = 0;
> -	int			dswidth = 0;
> -	uint8_t			iosizelog = 0;
> +
> +	struct fs_context	fc;
> +	struct xfs_fs_context	context;
> +	struct xfs_fs_context	*ctx = &context;

I don't really see the point for having a separate pointer variable
based on the code so far. Why not just do:

	struct xfs_fs_context	ctx = {0,};

... and pass by reference where necessary?

>  
>  	/*
>  	 * set up the mount name first so all the errors will refer to the
> @@ -406,17 +407,41 @@ xfs_parseargs(
>  	if (!options)
>  		goto done;
>  
> +	memset(&fc, 0, sizeof(fc));
> +	memset(&ctx, 0, sizeof(ctx));
> +	fc.fs_private = ctx;
> +	fc.s_fs_info = mp;
> +
>  	while ((p = strsep(&options, ",")) != NULL) {
> -		int		token;
> -		int		ret;
> +		struct fs_parameter	param;
> +		char			*value;
> +		int			ret;
>  
>  		if (!*p)
>  			continue;
>  
> -		token = match_token(p, tokens, args);
> -		ret = xfs_parse_param(token, p, args, mp,
> -				      &dsunit, &dswidth, &iosizelog);
> -		if (ret)
> +		param.key = p;
> +		param.type = fs_value_is_string;
> +		param.size = 0;
> +
> +		value = strchr(p, '=');
> +		if (value) {
> +			if (value == p)
> +				continue;

What's the purpose of the above check? Why do we skip the param as
opposed to return an error or something?

> +			*value++ = 0;
> +			param.size = strlen(value);
> +			if (param.size > 0) {
> +				param.string = kmemdup_nul(value,
> +							   param.size,
> +							   GFP_KERNEL);
> +				if (!param.string)
> +					return -ENOMEM;
> +			}
> +		}
> +
> +		ret = xfs_parse_param(&fc, &param);
> +		kfree(param.string);
> +		if (ret < 0)
>  			return ret;
>  	}
>  
...
> @@ -1914,6 +1939,10 @@ static const struct super_operations xfs_super_operations = {
>  	.free_cached_objects	= xfs_fs_free_cached_objects,
>  };
>  
> +static const struct fs_context_operations xfs_context_ops = {
> +	.parse_param = xfs_parse_param,
> +};
> +

It's probably better to introduce this in the first patch where it's used.

Brian

>  static struct file_system_type xfs_fs_type = {
>  	.owner			= THIS_MODULE,
>  	.name			= "xfs",
>