commit c614b5785876c46cb15fd3f340f739926e913859
Author: Andi Kleen <ak@linux.intel.com>
Date:   Wed Apr 6 15:12:41 2011 -0700

    Fix io_submit decoding in strace
    
    strace didn't decode important fields in the iocb passed to io_submit.
    This patch changes the code to dump them all. Also I prefixed the fields
    with names to make it easier to read.

diff --git a/desc.c b/desc.c
index 2b9f30a..57dc755 100644
--- a/desc.c
+++ b/desc.c
@@ -806,6 +806,51 @@ sys_io_destroy(struct tcb *tcp)
 	return 0;
 }
 
+#define ARRAY_SIZE(x) (sizeof(x)/sizeof(*(x)))
+
+enum iocb_sub {
+	SUB_NONE, SUB_COMMON, SUB_POLL, SUB_VECTOR
+};
+
+static const char *
+iocb_cmd_lookup(unsigned cmd, enum iocb_sub *sub)
+{
+	static char buf[20];
+	static struct {
+		const char *name;
+		enum iocb_sub sub;
+	} cmds[] = { 
+		{ "pread", SUB_COMMON },
+		{ "pwrite", SUB_COMMON },
+		{ "fsync", SUB_NONE },
+		{ "fdsync", SUB_NONE },
+		{ "op4", SUB_NONE },
+		{ "poll", SUB_POLL },
+		{ "noop", SUB_NONE },
+		{ "preadv", SUB_VECTOR },
+		{ "pwritev", SUB_VECTOR },
+	};
+
+	if (cmd < ARRAY_SIZE(cmds)) {
+		*sub = cmds[cmd].sub;
+		return cmds[cmd].name;
+	}
+	*sub = SUB_NONE;
+	snprintf(buf, sizeof buf, "?%u?", cmd); 
+	return buf;
+}
+
+/* Not defined in libaio.h */
+#define IOCB_RESFD (1 << 0)
+
+static void
+print_common_flags(struct iocb *iocb)
+{
+     if (iocb->u.c.flags & IOCB_RESFD)
+	     tprintf("resfd=%d, ", iocb->u.c.resfd);
+     if (iocb->u.c.flags & ~IOCB_RESFD)
+	     tprintf("flags=%x, ", iocb->u.c.flags);
+}
 int
 sys_io_submit(struct tcb *tcp)
 {
@@ -822,7 +867,9 @@ sys_io_submit(struct tcb *tcp)
 			struct iocb *iocbp, **iocbs = (void *)tcp->u_arg[2];
 
 			for (i = 0; i < nr; i++, iocbs++) {
+				enum iocb_sub sub;
 				struct iocb iocb;
+				int k;
 				if (i == 0)
 					tprintf("{");
 				else
@@ -833,10 +880,45 @@ sys_io_submit(struct tcb *tcp)
 					tprintf("{...}");
 					continue;
 				}
-				tprintf("{%p, %u, %hu, %hu, %d}",
-					iocb.data, iocb.key,
-					iocb.aio_lio_opcode,
-					iocb.aio_reqprio, iocb.aio_fildes);
+				tprintf("{");
+				if (iocb.data)
+					tprintf("data:%p, ", iocb.data);
+				if (iocb.key)
+					tprintf("key:%u, ", iocb.key);
+				tprintf("%s, ", iocb_cmd_lookup(iocb.aio_lio_opcode, &sub));
+				if (iocb.aio_reqprio)
+					tprintf("reqprio:%d, ", iocb.aio_reqprio);
+				tprintf("filedes:%d", iocb.aio_fildes);
+				switch (sub) {
+				case SUB_COMMON:
+					tprintf(", buf:%p, nbytes:%lu, offset:%llx", 
+						iocb.u.c.buf,
+						iocb.u.c.nbytes,
+						iocb.u.c.offset);
+					print_common_flags(&iocb);
+					break;
+				case SUB_VECTOR:
+					tprintf(", %llx, ", iocb.u.v.offset);
+					print_common_flags(&iocb);
+					for (k = 0; k < iocb.u.v.nr; k++) {
+						struct iovec iov;
+						tprintf("%s", k == 0 ? "" : ", ");
+						if (umove(tcp, (unsigned long)iocb.u.v.vec + 
+								sizeof(struct iovec)*k, &iov))
+							tprintf("{...}");
+						else
+							tprintf("{ %p, %lu }", 
+								iov.iov_base, 
+								iov.iov_len);
+					}
+					break;
+				case SUB_POLL:
+					tprintf(", %x", iocb.u.poll.events);
+					break;
+				case SUB_NONE:
+				        break;
+				}
+				tprintf("}");
 			}
 			if (i)
 				tprintf("}");