bcache: Performance fix for when journal entry is full

We were unnecessarily waiting on a journal write to complete when we just needed
to start a journal write and start setting up the next one.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 29cccc510eb6..ad687285c2df 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -673,6 +673,7 @@ static struct journal_write *journal_wait_for_write(struct cache_set *c,
 {
         size_t sectors;
         struct closure cl;
+        bool wait = false;
 
         closure_init_stack(&cl);
 
@@ -689,9 +690,12 @@ static struct journal_write *journal_wait_for_write(struct cache_set *c,
                                      PAGE_SECTORS << JSET_BITS))
                         return w;
 
-                /* XXX: tracepoint */
+                if (wait)
+                        closure_wait(&c->journal.wait, &cl);
+
                 if (!journal_full(&c->journal)) {
-                        trace_bcache_journal_entry_full(c);
+                        if (wait)
+                                trace_bcache_journal_entry_full(c);
 
                         /*
                          * XXX: If we were inserting so many keys that they
@@ -701,12 +705,11 @@ static struct journal_write *journal_wait_for_write(struct cache_set *c,
                          */
                         BUG_ON(!w->data->keys);
 
-                        closure_wait(&w->wait, &cl);
                         journal_try_write(c); /* unlocks */
                 } else {
-                        trace_bcache_journal_full(c);
+                        if (wait)
+                                trace_bcache_journal_full(c);
 
-                        closure_wait(&c->journal.wait, &cl);
                         journal_reclaim(c);
                         spin_unlock(&c->journal.lock);
 
@@ -715,6 +718,7 @@ static struct journal_write *journal_wait_for_write(struct cache_set *c,
 
                 closure_sync(&cl);
                 spin_lock(&c->journal.lock);
+                wait = true;
         }
 }