bcache: Fix/revamp tracepoints

The tracepoints were reworked to be more sensible, and fixed a null
pointer deref in one of the tracepoints.

Converted some of the pr_debug()s to tracepoints - this is partly a
performance optimization; it used to be that with DEBUG or
CONFIG_DYNAMIC_DEBUG pr_debug() was an empty macro; but at some point it
was changed to an empty inline function.

Some of the pr_debug() statements had rather expensive function calls as
part of the arguments, so this code was getting run unnecessarily even
on non debug kernels - in some fast paths, too.

Signed-off-by: Kent Overstreet <koverstreet@google.com>

1 files changed, 5 insertions, 7 deletions

diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
index 8589512c972e..04f6b97ffda6 100644
--- a/drivers/md/bcache/movinggc.c
+++ b/drivers/md/bcache/movinggc.c
@@ -9,6 +9,8 @@
 #include "debug.h"
 #include "request.h"
 
+#include <trace/events/bcache.h>
+
 struct moving_io {
         struct keybuf_key       *w;
         struct search           s;
@@ -49,9 +51,8 @@ static void write_moving_finish(struct closure *cl)
         while (bv-- != bio->bi_io_vec)
                 __free_page(bv->bv_page);
 
-        pr_debug("%s %s", io->s.op.insert_collision
-                 ? "collision moving" : "moved",
-                 pkey(&io->w->key));
+        if (io->s.op.insert_collision)
+                trace_bcache_gc_copy_collision(&io->w->key);
 
         bch_keybuf_del(&io->s.op.c->moving_gc_keys, io->w);
 
@@ -94,8 +95,6 @@ static void write_moving(struct closure *cl)
         struct moving_io *io = container_of(s, struct moving_io, s);
 
         if (!s->error) {
-                trace_bcache_write_moving(&io->bio.bio);
-
                 moving_init(io);
 
                 io->bio.bio.bi_sector   = KEY_START(&io->w->key);
@@ -122,7 +121,6 @@ static void read_moving_submit(struct closure *cl)
         struct moving_io *io = container_of(s, struct moving_io, s);
         struct bio *bio = &io->bio.bio;
 
-        trace_bcache_read_moving(bio);
         bch_submit_bbio(bio, s->op.c, &io->w->key, 0);
 
         continue_at(cl, write_moving, bch_gc_wq);
@@ -162,7 +160,7 @@ static void read_moving(struct closure *cl)
                 if (bch_bio_alloc_pages(bio, GFP_KERNEL))
                         goto err;
 
-                pr_debug("%s", pkey(&w->key));
+                trace_bcache_gc_copy(&w->key);
 
                 closure_call(&io->s.cl, read_moving_submit, NULL, &c->gc.cl);