staging/lustre/hsm: HSM requests not delivered

The total size of an HSM archive request may exceed the
desired (LNET) message. When this happens, it can hang
the client and not allow the archive request to succeed.

Before we know the total size of the hsm_action_items, we
need to limit the size of the reguest. Doing this limits
the number of items that can be sent in one archive request.
We'e reduced the size allowed for the user archive request
to MDS_MAXREQSIZE/3.
Signed-off-by: NJames Nunez <james.a.nunez@intel.com>
Reviewed-on: http://review.whamcloud.com/9393
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4639Reviewed-by: NJohn L. Hammond <john.hammond@intel.com>
Reviewed-by: NJinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: NOleg Drokin <oleg.drokin@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lustre_net.h

@@ -264,6 +264,8 @@
 #define LDLM_MAXREQSIZE   (5 * 1024)
 #define LDLM_MAXREPSIZE   (1024)
 
+#define MDS_MAXREQSIZE		(5 * 1024)	/* >= 4736 */
+
 #define OST_MAXREQSIZE		(5 * 1024)
 
 /* Macro to hide a typecast. */

drivers/staging/lustre/lustre/llite/dir.c

@@ -1804,6 +1804,11 @@ static long ll_dir_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		/* Compute the whole struct size */
 		totalsize = hur_len(hur);
 		OBD_FREE_PTR(hur);
+
+		/* Final size will be more than double totalsize */
+		if (totalsize >= MDS_MAXREQSIZE / 3)
+			return -E2BIG;
+
 		OBD_ALLOC_LARGE(hur, totalsize);
 		if (hur == NULL)
 			return -ENOMEM;