[pnfs] [PATCH 21/37] pnfs: client layout cache: unlock layout around call to get_layout

[Dean Hildebrand]

Benny Halevy wrote:
> get_layout sends an rpc to the server so the layout spinlock should be
> released around the call.
>
> Signed-off-by: Benny Halevy <bhalevy at panasas.com>
> ---
>  fs/nfs/pnfs.c |   19 ++++++++++++-------
>  1 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index d11145c..edc087c 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -578,8 +578,6 @@ pnfs_update_layout(struct inode *ino,
>  		return 0; /* Already have layout information */
>  	}
>  
> -	res.layout.buf = NULL;
> -
>  	/* if get layout already failed once goto out */
>  	if (nfsi->pnfs_layout_state & NFS_INO_LAYOUT_FAILED) {
>  		if (unlikely(nfsi->pnfs_layout_suspend &&
> @@ -593,7 +591,14 @@ pnfs_update_layout(struct inode *ino,
>  		}
>  	}
>  
> +	res.layout.buf = NULL;
> +	spin_unlock(&nfsi->lo_lock);
>  	result = get_layout(ino, ctx, &arg, &res);
> +	spin_lock(&nfsi->lo_lock);
> +
> +	/* we got a reference on current_layout */
> +	BUG_ON(nfsi->current_layout != layout_new);
> +
>   
Couldn't something have happened while the lock was released?  Does this 
need to be checked?  If not, maybe some comments could explain the 
situation.
Dean
>  	if (result) {
>  		printk(KERN_ERR "%s: ERROR retrieving layout %d\n",
>  		       __FUNCTION__, result);
> @@ -620,14 +625,14 @@ pnfs_update_layout(struct inode *ino,
>  			/* mark with NFS_INO_LAYOUT_FAILED */
>  			break;
>  		}
> -		goto out;
> +		goto get_out;
>  	}
>  
>  	if (res.layout.len <= 0) {
>  		printk(KERN_ERR
>  		       "%s: ERROR!  Layout size is ZERO!\n", __FUNCTION__);
>  		result =  -EIO;
> -		goto out;
> +		goto get_out;
>  	}
>  
>  	/* Inject layout blob into I/O device driver */
> @@ -637,7 +642,7 @@ pnfs_update_layout(struct inode *ino,
>  		printk(KERN_ERR "%s: ERROR!  Could not inject layout (%d)\n",
>  		       __FUNCTION__, result);
>  		result =  -EIO;
> -		goto out;
> +		goto get_out;
>  	}
>  
>  	if (res.return_on_close) {
> @@ -648,14 +653,14 @@ pnfs_update_layout(struct inode *ino,
>  	nfsi->current_layout = layout_new;
>  
>  	result = 0;
> -out:
> -
> +get_out:
>  	/* remember that get layout failed and don't try again */
>  	if (result < 0)
>  		nfsi->pnfs_layout_state |= NFS_INO_LAYOUT_FAILED;
>  
>  	/* res.layout.buf kalloc'ed by the xdr decoder? */
>  	kfree(res.layout.buf);
> +out:
>  	put_unlock_current_layout(nfsi, layout_new);
>  ret:
>  	dprintk("%s end (err:%d) state 0x%lx\n",
>