[lustre-devel] [PATCH] lustre: fix inode refcount problem with fhandle access

[James Simmons]

> ll_iget_for_nfs() currently calls d_obtain_alias() twice.
> This decrements the refcount on the inode twice, and
> increments it on the dentry twice.
> In each case, only once is correct.
> The result is that the refcounts are wrong and warnings
> result.
> 
> Also, if the first d_obtain_alias() returns an error,
> iput() is called.  As the comment at the second d_obtain_alias()
> explains, this is incorrect.

Fixed my problems!!! Thank you.

Reviewed-by: James Simmons <jsimmons at infradead.org>
 
> Reported-by: James Simmons <jsimmons at infradead.org>
> Signed-off-by: NeilBrown <neilb at suse.com>
> ---
>  drivers/staging/lustre/lustre/llite/llite_nfs.c | 20 +++++++-------------
>  1 file changed, 7 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/llite/llite_nfs.c b/drivers/staging/lustre/lustre/llite/llite_nfs.c
> index 14172688d55f..9efb20e91476 100644
> --- a/drivers/staging/lustre/lustre/llite/llite_nfs.c
> +++ b/drivers/staging/lustre/lustre/llite/llite_nfs.c
> @@ -150,10 +150,8 @@ ll_iget_for_nfs(struct super_block *sb,
>  	}
>  
>  	result = d_obtain_alias(inode);
> -	if (IS_ERR(result)) {
> -		iput(inode);
> +	if (IS_ERR(result))
>  		return result;
> -	}
>  
>  	/**
>  	 * In case d_obtain_alias() found a disconnected dentry, always update
> @@ -168,16 +166,12 @@ ll_iget_for_nfs(struct super_block *sb,
>  		spin_unlock(&lli->lli_lock);
>  	}
>  
> -	/* N.B. d_obtain_alias() drops inode ref on error */
> -	result = d_obtain_alias(inode);
> -	if (!IS_ERR(result)) {
> -		/*
> -		 * Need to signal to the ll_intent_file_open that
> -		 * we came from NFS and so opencache needs to be
> -		 * enabled for this one
> -		 */
> -		ll_d2d(result)->lld_nfs_dentry = 1;
> -	}
> +	/*
> +	 * Need to signal to the ll_intent_file_open that
> +	 * we came from NFS and so opencache needs to be
> +	 * enabled for this one
> +	 */
> +	ll_d2d(result)->lld_nfs_dentry = 1;
>  
>  	return result;
>  }
> -- 
> 2.14.0.rc0.dirty
> 
>