NFS: Save struct inode * inside nfs_commit_info to clarify usage of i_lock

Commit ea2cf22 created nfs_commit_info and saved &inode->i_lock inside
this NFS specific structure.  This obscures the usage of i_lock.
Instead, save struct inode * so later it's clear the spinlock taken is
i_lock.

Should be no functional change.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 0cb1abd..3b398f7 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -745,7 +745,7 @@
 	else {
 		int i;
 
-		spin_lock(cinfo->lock);
+		spin_lock(&cinfo->inode->i_lock);
 		if (cinfo->ds->nbuckets != 0)
 			kfree(buckets);
 		else {
@@ -759,7 +759,7 @@
 					NFS_INVALID_STABLE_HOW;
 			}
 		}
-		spin_unlock(cinfo->lock);
+		spin_unlock(&cinfo->inode->i_lock);
 		return 0;
 	}
 }