Re: nfsd: skip some unnecessary stats in the v4 case

[Colin Ian King <colin.king@canonical.com>]

On 25/11/2020 16:47, J. Bruce Fields wrote:
> On Wed, Nov 25, 2020 at 02:50:51PM +0000, Colin Ian King wrote:
>> Static analysis on today's linux-next has found an issue with the
>> following commit:
> 
> Thanks!  I'll probably do something like this.

Looks good to me, even if it is a little more convoluted. Thanks.

> 
> Though this still all seems slightly more complicated than necessary.
> 
> --b.
> 
> diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
> index 8502a493be6d..7eb761801169 100644
> --- a/fs/nfsd/nfs3xdr.c
> +++ b/fs/nfsd/nfs3xdr.c
> @@ -260,13 +260,12 @@ void fill_pre_wcc(struct svc_fh *fhp)
>  	struct inode    *inode;
>  	struct kstat	stat;
>  	bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
> -	__be32 err;
>  
>  	if (fhp->fh_pre_saved)
>  		return;
>  	inode = d_inode(fhp->fh_dentry);
>  	if (!v4 || !inode->i_sb->s_export_op->fetch_iversion) {
> -		err = fh_getattr(fhp, &stat);
> +		__be32 err = fh_getattr(fhp, &stat);
>  		if (err) {
>  			/* Grab the times from inode anyway */
>  			stat.mtime = inode->i_mtime;
> @@ -290,23 +289,23 @@ void fill_post_wcc(struct svc_fh *fhp)
>  {
>  	bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE);
>  	struct inode *inode = d_inode(fhp->fh_dentry);
> -	__be32 err;
>  
>  	if (fhp->fh_post_saved)
>  		printk("nfsd: inode locked twice during operation.\n");
>  
> +	fhp->fh_post_saved = true;
>  
> -	if (!v4 || !inode->i_sb->s_export_op->fetch_iversion)
> -		err = fh_getattr(fhp, &fhp->fh_post_attr);
> +	if (!v4 || !inode->i_sb->s_export_op->fetch_iversion) {
> +		__be32 err = fh_getattr(fhp, &fhp->fh_post_attr);
> +		if (err) {
> +			fhp->fh_post_saved = false;
> +			/* set_change_info might still need this: */
> +			fhp->fh_post_attr.ctime = inode->i_ctime;
> +		}
> +	}
>  	if (v4)
>  		fhp->fh_post_change =
>  			nfsd4_change_attribute(&fhp->fh_post_attr, inode);
> -	if (err) {
> -		fhp->fh_post_saved = false;
> -		/* Grab the ctime anyway - set_change_info might use it */
> -		fhp->fh_post_attr.ctime = inode->i_ctime;
> -	} else
> -		fhp->fh_post_saved = true;
>  }
>  
>  /*
>