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, 24 insertions, 23 deletions

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index aaec186f7ba6..218d486259a3 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -223,8 +223,9 @@ void bch_btree_node_read(struct btree *b)
         struct closure cl;
         struct bio *bio;
 
+        trace_bcache_btree_read(b);
+
         closure_init_stack(&cl);
-        pr_debug("%s", pbtree(b));
 
         bio = bch_bbio_alloc(b->c);
         bio->bi_rw      = REQ_META|READ_SYNC;
@@ -234,7 +235,6 @@ void bch_btree_node_read(struct btree *b)
 
         bch_bio_map(bio, b->sets[0].data);
 
-        trace_bcache_btree_read(bio);
         bch_submit_bbio(bio, b->c, &b->key, 0);
         closure_sync(&cl);
 
@@ -343,7 +343,6 @@ static void do_btree_node_write(struct btree *b)
                         memcpy(page_address(bv->bv_page),
                                base + j * PAGE_SIZE, PAGE_SIZE);
 
-                trace_bcache_btree_write(b->bio);
                 bch_submit_bbio(b->bio, b->c, &k.key, 0);
 
                 continue_at(cl, btree_node_write_done, NULL);
@@ -351,7 +350,6 @@ static void do_btree_node_write(struct btree *b)
                 b->bio->bi_vcnt = 0;
                 bch_bio_map(b->bio, i);
 
-                trace_bcache_btree_write(b->bio);
                 bch_submit_bbio(b->bio, b->c, &k.key, 0);
 
                 closure_sync(cl);
@@ -363,10 +361,13 @@ void bch_btree_node_write(struct btree *b, struct closure *parent)
 {
         struct bset *i = b->sets[b->nsets].data;
 
+        trace_bcache_btree_write(b);
+
         BUG_ON(current->bio_list);
         BUG_ON(b->written >= btree_blocks(b));
         BUG_ON(b->written && !i->keys);
         BUG_ON(b->sets->data->seq != i->seq);
+        bch_check_key_order(b, i);
 
         cancel_delayed_work(&b->work);
 
@@ -376,12 +377,8 @@ void bch_btree_node_write(struct btree *b, struct closure *parent)
         clear_bit(BTREE_NODE_dirty,      &b->flags);
         change_bit(BTREE_NODE_write_idx, &b->flags);
 
-        bch_check_key_order(b, i);
-
         do_btree_node_write(b);
 
-        pr_debug("%s block %i keys %i", pbtree(b), b->written, i->keys);
-
         b->written += set_blocks(i, b->c);
         atomic_long_add(set_blocks(i, b->c) * b->c->sb.block_size,
                         &PTR_CACHE(b->c, &b->key, 0)->btree_sectors_written);
@@ -752,6 +749,8 @@ static struct btree *mca_cannibalize(struct cache_set *c, struct bkey *k,
         int ret = -ENOMEM;
         struct btree *i;
 
+        trace_bcache_btree_cache_cannibalize(c);
+
         if (!cl)
                 return ERR_PTR(-ENOMEM);
 
@@ -770,7 +769,6 @@ static struct btree *mca_cannibalize(struct cache_set *c, struct bkey *k,
                 return ERR_PTR(-EAGAIN);
         }
 
-        /* XXX: tracepoint */
         c->try_harder = cl;
         c->try_harder_start = local_clock();
 retry:
@@ -956,13 +954,14 @@ static void btree_node_free(struct btree *b, struct btree_op *op)
 {
         unsigned i;
 
+        trace_bcache_btree_node_free(b);
+
         /*
          * The BUG_ON() in btree_node_get() implies that we must have a write
          * lock on parent to free or even invalidate a node
          */
         BUG_ON(op->lock <= b->level);
         BUG_ON(b == b->c->root);
-        pr_debug("bucket %s", pbtree(b));
 
         if (btree_node_dirty(b))
                 btree_complete_write(b, btree_current_write(b));
@@ -1012,12 +1011,16 @@ retry:
         bch_bset_init_next(b);
 
         mutex_unlock(&c->bucket_lock);
+
+        trace_bcache_btree_node_alloc(b);
         return b;
 err_free:
         bch_bucket_free(c, &k.key);
         __bkey_put(c, &k.key);
 err:
         mutex_unlock(&c->bucket_lock);
+
+        trace_bcache_btree_node_alloc_fail(b);
         return b;
 }
 
@@ -1254,7 +1257,7 @@ static void btree_gc_coalesce(struct btree *b, struct btree_op *op,
         btree_node_free(r->b, op);
         up_write(&r->b->lock);
 
-        pr_debug("coalesced %u nodes", nodes);
+        trace_bcache_btree_gc_coalesce(nodes);
 
         gc->nodes--;
         nodes--;
@@ -1479,8 +1482,7 @@ static void bch_btree_gc(struct closure *cl)
         struct btree_op op;
         uint64_t start_time = local_clock();
 
-        trace_bcache_gc_start(c->sb.set_uuid);
-        blktrace_msg_all(c, "Starting gc");
+        trace_bcache_gc_start(c);
 
         memset(&stats, 0, sizeof(struct gc_stat));
         closure_init_stack(&writes);
@@ -1496,9 +1498,7 @@ static void bch_btree_gc(struct closure *cl)
         closure_sync(&writes);
 
         if (ret) {
-                blktrace_msg_all(c, "Stopped gc");
                 pr_warn("gc failed!");
-
                 continue_at(cl, bch_btree_gc, bch_gc_wq);
         }
 
@@ -1519,8 +1519,7 @@ static void bch_btree_gc(struct closure *cl)
         stats.in_use    = (c->nbuckets - available) * 100 / c->nbuckets;
         memcpy(&c->gc_stats, &stats, sizeof(struct gc_stat));
 
-        blktrace_msg_all(c, "Finished gc");
-        trace_bcache_gc_end(c->sb.set_uuid);
+        trace_bcache_gc_end(c);
 
         continue_at(cl, bch_moving_gc, bch_gc_wq);
 }
@@ -1901,12 +1900,11 @@ static int btree_split(struct btree *b, struct btree_op *op)
 
         split = set_blocks(n1->sets[0].data, n1->c) > (btree_blocks(b) * 4) / 5;
 
-        pr_debug("%ssplitting at %s keys %i", split ? "" : "not ",
-                 pbtree(b), n1->sets[0].data->keys);
-
         if (split) {
                 unsigned keys = 0;
 
+                trace_bcache_btree_node_split(b, n1->sets[0].data->keys);
+
                 n2 = bch_btree_node_alloc(b->c, b->level, &op->cl);
                 if (IS_ERR(n2))
                         goto err_free1;
@@ -1941,8 +1939,11 @@ static int btree_split(struct btree *b, struct btree_op *op)
                 bch_keylist_add(&op->keys, &n2->key);
                 bch_btree_node_write(n2, &op->cl);
                 rw_unlock(true, n2);
-        } else
+        } else {
+                trace_bcache_btree_node_compact(b, n1->sets[0].data->keys);
+
                 bch_btree_insert_keys(n1, op);
+        }
 
         bch_keylist_add(&op->keys, &n1->key);
         bch_btree_node_write(n1, &op->cl);
@@ -2117,6 +2118,8 @@ void bch_btree_set_root(struct btree *b)
 {
         unsigned i;
 
+        trace_bcache_btree_set_root(b);
+
         BUG_ON(!b->written);
 
         for (i = 0; i < KEY_PTRS(&b->key); i++)
@@ -2130,7 +2133,6 @@ void bch_btree_set_root(struct btree *b)
         __bkey_put(b->c, &b->key);
 
         bch_journal_meta(b->c, NULL);
-        pr_debug("%s for %pf", pbtree(b), __builtin_return_address(0));
 }
 
 /* Cache lookup */
@@ -2216,7 +2218,6 @@ static int submit_partial_cache_hit(struct btree *b, struct btree_op *op,
                 n->bi_end_io    = bch_cache_read_endio;
                 n->bi_private   = &s->cl;
 
-                trace_bcache_cache_hit(n);
                 __bch_submit_bbio(n, b->c);
         }