Initial commit of an I/O provider for DTrace on FreeBSD.

These probes are most useful when looking into the structures
they provide, which are listed in io.d.  For example:

dtrace -n 'io:genunix::start { printf("%d\n", args[0]->bio_bcount); }'

Note that the I/O systems in FreeBSD and Solaris/Illumos are sufficiently
different that there is not a 1:1 mapping from scripts that work
with one to the other.
MFC after:	1 month

1 files changed, 19 insertions, 0 deletions

diff --git a/sys/sys/dtrace_bsd.h b/sys/sys/dtrace_bsd.h
index eb348b28f184..2198b264db2f 100644
--- a/sys/sys/dtrace_bsd.h
+++ b/sys/sys/dtrace_bsd.h
@@ -38,6 +38,8 @@ struct thread;
 struct vattr;
 struct vnode;
 struct reg;
+struct devstat;
+struct bio;
 
 /*
  * Cyclic clock function type definition used to hook the cyclic
@@ -168,6 +170,23 @@ extern dtrace_nfsclient_nfs23_done_probe_func_t
 extern dtrace_nfsclient_nfs23_done_probe_func_t
     dtrace_nfscl_nfs234_done_probe;
 
+/* IO Provider hooks, really hook into devstat */
+typedef void (*dtrace_io_start_probe_func_t)(uint32_t, struct bio *,
+					     struct devstat *);
+extern dtrace_io_start_probe_func_t dtrace_io_start_probe;
+
+typedef void (*dtrace_io_done_probe_func_t)(uint32_t, struct bio *,
+					    struct devstat *);
+extern dtrace_io_done_probe_func_t dtrace_io_done_probe;
+
+typedef void (*dtrace_io_wait_start_probe_func_t)(uint32_t, uintptr_t *, 
+						  struct devstat *);
+extern dtrace_io_wait_start_probe_func_t dtrace_io_wait_start_probe;
+
+typedef void (*dtrace_io_wait_done_probe_func_t)(uint32_t, uintptr_t *, 
+						 struct devstat *);
+extern dtrace_io_wait_done_probe_func_t dtrace_io_wait_done_probe;
+
 /*
  * Functions which allow the dtrace module to check that the kernel 
  * hooks have been compiled with sufficient space for it's private