staging: lustre: llite: handle xattr cache refill race

In ll_xattr_cache_refill() if the xattr cache was invalid (and no
request was sent) then return -EAGAIN so that ll_getxattr_common()
caller will fetch the xattr from the MDT.
Signed-off-by: John L. Hammond <john.hammond@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-10132
Reviewed-on: https://review.whamcloud.com/29654Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/xattr_cache.c

@@ -357,7 +357,7 @@ static int ll_xattr_cache_refill(struct inode *inode)
 	if (unlikely(!req)) {
 		CDEBUG(D_CACHE, "cancelled by a parallel getxattr\n");
 		ll_intent_drop_lock(&oit);
-		rc = -EIO;
+		rc = -EAGAIN;
 		goto err_unlock;
 	}