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, 241 insertions, 111 deletions

diff --git a/include/trace/events/bcache.h b/include/trace/events/bcache.h
index 3cc5a0b278c3..c9952b36fcea 100644
--- a/include/trace/events/bcache.h
+++ b/include/trace/events/bcache.h
@@ -9,9 +9,7 @@
 struct search;
 
 DECLARE_EVENT_CLASS(bcache_request,
-
         TP_PROTO(struct search *s, struct bio *bio),
-
         TP_ARGS(s, bio),
 
         TP_STRUCT__entry(
@@ -22,7 +20,6 @@ DECLARE_EVENT_CLASS(bcache_request,
                 __field(dev_t,          orig_sector             )
                 __field(unsigned int,   nr_sector               )
                 __array(char,           rwbs,   6               )
-                __array(char,           comm,   TASK_COMM_LEN   )
         ),
 
         TP_fast_assign(
@@ -33,36 +30,66 @@ DECLARE_EVENT_CLASS(bcache_request,
                 __entry->orig_sector    = bio->bi_sector - 16;
                 __entry->nr_sector      = bio->bi_size >> 9;
                 blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
-                memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
         ),
 
-        TP_printk("%d,%d %s %llu + %u [%s] (from %d,%d @ %llu)",
+        TP_printk("%d,%d %s %llu + %u (from %d,%d @ %llu)",
                   MAJOR(__entry->dev), MINOR(__entry->dev),
-                  __entry->rwbs,
-                  (unsigned long long)__entry->sector,
-                  __entry->nr_sector, __entry->comm,
-                  __entry->orig_major, __entry->orig_minor,
+                  __entry->rwbs, (unsigned long long)__entry->sector,
+                  __entry->nr_sector, __entry->orig_major, __entry->orig_minor,
                   (unsigned long long)__entry->orig_sector)
 );
 
-DEFINE_EVENT(bcache_request, bcache_request_start,
+DECLARE_EVENT_CLASS(bkey,
+        TP_PROTO(struct bkey *k),
+        TP_ARGS(k),
 
-        TP_PROTO(struct search *s, struct bio *bio),
+        TP_STRUCT__entry(
+                __field(u32,    size                            )
+                __field(u32,    inode                           )
+                __field(u64,    offset                          )
+                __field(bool,   dirty                           )
+        ),
 
-        TP_ARGS(s, bio)
+        TP_fast_assign(
+                __entry->inode  = KEY_INODE(k);
+                __entry->offset = KEY_OFFSET(k);
+                __entry->size   = KEY_SIZE(k);
+                __entry->dirty  = KEY_DIRTY(k);
+        ),
+
+        TP_printk("%u:%llu len %u dirty %u", __entry->inode,
+                  __entry->offset, __entry->size, __entry->dirty)
 );
 
-DEFINE_EVENT(bcache_request, bcache_request_end,
+DECLARE_EVENT_CLASS(btree_node,
+        TP_PROTO(struct btree *b),
+        TP_ARGS(b),
+
+        TP_STRUCT__entry(
+                __field(size_t,         bucket                  )
+        ),
+
+        TP_fast_assign(
+                __entry->bucket = PTR_BUCKET_NR(b->c, &b->key, 0);
+        ),
 
+        TP_printk("bucket %zu", __entry->bucket)
+);
+
+/* request.c */
+
+DEFINE_EVENT(bcache_request, bcache_request_start,
         TP_PROTO(struct search *s, struct bio *bio),
+        TP_ARGS(s, bio)
+);
 
+DEFINE_EVENT(bcache_request, bcache_request_end,
+        TP_PROTO(struct search *s, struct bio *bio),
         TP_ARGS(s, bio)
 );
 
 DECLARE_EVENT_CLASS(bcache_bio,
-
         TP_PROTO(struct bio *bio),
-
         TP_ARGS(bio),
 
         TP_STRUCT__entry(
@@ -70,7 +97,6 @@ DECLARE_EVENT_CLASS(bcache_bio,
                 __field(sector_t,       sector                  )
                 __field(unsigned int,   nr_sector               )
                 __array(char,           rwbs,   6               )
-                __array(char,           comm,   TASK_COMM_LEN   )
         ),
 
         TP_fast_assign(
@@ -78,191 +104,295 @@ DECLARE_EVENT_CLASS(bcache_bio,
                 __entry->sector         = bio->bi_sector;
                 __entry->nr_sector      = bio->bi_size >> 9;
                 blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
-                memcpy(__entry->comm, current->comm, TASK_COMM_LEN);
         ),
 
-        TP_printk("%d,%d  %s %llu + %u [%s]",
-                  MAJOR(__entry->dev), MINOR(__entry->dev),
-                  __entry->rwbs,
-                  (unsigned long long)__entry->sector,
-                  __entry->nr_sector, __entry->comm)
+        TP_printk("%d,%d  %s %llu + %u",
+                  MAJOR(__entry->dev), MINOR(__entry->dev), __entry->rwbs,
+                  (unsigned long long)__entry->sector, __entry->nr_sector)
 );
 
-
-DEFINE_EVENT(bcache_bio, bcache_passthrough,
-
+DEFINE_EVENT(bcache_bio, bcache_bypass_sequential,
         TP_PROTO(struct bio *bio),
-
         TP_ARGS(bio)
 );
 
-DEFINE_EVENT(bcache_bio, bcache_cache_hit,
-
+DEFINE_EVENT(bcache_bio, bcache_bypass_congested,
         TP_PROTO(struct bio *bio),
-
         TP_ARGS(bio)
 );
 
-DEFINE_EVENT(bcache_bio, bcache_cache_miss,
+TRACE_EVENT(bcache_read,
+        TP_PROTO(struct bio *bio, bool hit, bool bypass),
+        TP_ARGS(bio, hit, bypass),
 
-        TP_PROTO(struct bio *bio),
+        TP_STRUCT__entry(
+                __field(dev_t,          dev                     )
+                __field(sector_t,       sector                  )
+                __field(unsigned int,   nr_sector               )
+                __array(char,           rwbs,   6               )
+                __field(bool,           cache_hit               )
+                __field(bool,           bypass                  )
+        ),
 
-        TP_ARGS(bio)
+        TP_fast_assign(
+                __entry->dev            = bio->bi_bdev->bd_dev;
+                __entry->sector         = bio->bi_sector;
+                __entry->nr_sector      = bio->bi_size >> 9;
+                blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
+                __entry->cache_hit = hit;
+                __entry->bypass = bypass;
+        ),
+
+        TP_printk("%d,%d  %s %llu + %u hit %u bypass %u",
+                  MAJOR(__entry->dev), MINOR(__entry->dev),