[SCSI] iscsi_tcp: make padbuf non-static

virt_to_page() call should not be used on kernel text and data
addresses.  virt_to_page() is used by sg_init_one(). So change padbuf
to be allocated within iscsi_segment.
Signed-off-by: Karen Xie <kxie@chelsio.com>
Acked-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/libiscsi_tcp.c

@@ -177,7 +177,6 @@ int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
 			   struct iscsi_segment *segment, int recv,
 			   unsigned copied)
 {
-	static unsigned char padbuf[ISCSI_PAD_LEN];
 	struct scatterlist sg;
 	unsigned int pad;
 
@@ -233,7 +232,7 @@ int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
 			debug_tcp("consume %d pad bytes\n", pad);
 			segment->total_size += pad;
 			segment->size = pad;
-			segment->data = padbuf;
+			segment->data = segment->padbuf;
 			return 0;
 		}
 	}

include/scsi/libiscsi_tcp.h

@@ -39,6 +39,7 @@ struct iscsi_segment {
 	unsigned int		total_copied;
 
 	struct hash_desc	*hash;
+	unsigned char		padbuf[ISCSI_PAD_LEN];
 	unsigned char		recv_digest[ISCSI_DIGEST_SIZE];
 	unsigned char		digest[ISCSI_DIGEST_SIZE];
 	unsigned int		digest_len;