bcache: Kill bucket->gc_gen

gc_gen was a temporary used to recalculate last_gc, but since we only need
bucket->last_gc when gc isn't running (gc_mark_valid = 1), we can just update
last_gc directly.

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

4 files changed, 9 insertions, 11 deletions

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 200efc1b5cf8..82c9c5d35251 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -196,7 +196,6 @@ struct bucket {
         uint16_t        prio;
         uint8_t         gen;
         uint8_t         last_gc; /* Most out of date gen in the btree */
-        uint8_t         gc_gen;
         uint16_t        gc_mark; /* Bitfield used by GC. See below for field */
 };
 
@@ -588,7 +587,7 @@ struct cache_set {
         uint16_t                min_prio;
 
         /*
-         * max(gen - gc_gen) for all buckets. When it gets too big we have to gc
+         * max(gen - last_gc) for all buckets. When it gets too big we have to gc
          * to keep gens from wrapping around.
          */
         uint8_t                 need_gc;
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 4c340c85b122..7347b6100961 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1178,8 +1178,8 @@ static uint8_t __bch_btree_mark_key(struct cache_set *c, int level,
 
                 g = PTR_BUCKET(c, k, i);
 
-                if (gen_after(g->gc_gen, PTR_GEN(k, i)))
-                        g->gc_gen = PTR_GEN(k, i);
+                if (gen_after(g->last_gc, PTR_GEN(k, i)))
+                        g->last_gc = PTR_GEN(k, i);
 
                 if (ptr_stale(c, k, i)) {
                         stale = max(stale, ptr_stale(c, k, i));
@@ -1631,7 +1631,7 @@ static void btree_gc_start(struct cache_set *c)
 
         for_each_cache(ca, c, i)
                 for_each_bucket(b, ca) {
-                        b->gc_gen = b->gen;
+                        b->last_gc = b->gen;
                         if (!atomic_read(&b->pin)) {
                                 SET_GC_MARK(b, 0);
                                 SET_GC_SECTORS_USED(b, 0);
@@ -1693,7 +1693,6 @@ static size_t bch_btree_gc_finish(struct cache_set *c)
                         SET_GC_MARK(ca->buckets + *i, GC_MARK_METADATA);
 
                 for_each_bucket(b, ca) {
-                        b->last_gc      = b->gc_gen;
                         c->need_gc      = max(c->need_gc, bucket_gc_gen(b));
 
                         if (atomic_read(&b->pin))
diff --git a/drivers/md/bcache/extents.c b/drivers/md/bcache/extents.c
index 82d5e3288a6c..35887330b49d 100644
--- a/drivers/md/bcache/extents.c
+++ b/drivers/md/bcache/extents.c
@@ -194,9 +194,9 @@ err:
         mutex_unlock(&b->c->bucket_lock);
         bch_extent_to_text(buf, sizeof(buf), k);
         btree_bug(b,
-"inconsistent btree pointer %s: bucket %zi pin %i prio %i gen %i last_gc %i mark %llu gc_gen %i",
+"inconsistent btree pointer %s: bucket %zi pin %i prio %i gen %i last_gc %i mark %llu",
                   buf, PTR_BUCKET_NR(b->c, k, i), atomic_read(&g->pin),
-                  g->prio, g->gen, g->last_gc, GC_MARK(g), g->gc_gen);
+                  g->prio, g->gen, g->last_gc, GC_MARK(g));
         return true;
 }
 
@@ -515,9 +515,9 @@ err:
         mutex_unlock(&b->c->bucket_lock);
         bch_extent_to_text(buf, sizeof(buf), k);
         btree_bug(b,
-"inconsistent extent pointer %s:\nbucket %zu pin %i prio %i gen %i last_gc %i mark %llu gc_gen %i",
+"inconsistent extent pointer %s:\nbucket %zu pin %i prio %i gen %i last_gc %i mark %llu",
                   buf, PTR_BUCKET_NR(b->c, k, ptr), atomic_read(&g->pin),
-                  g->prio, g->gen, g->last_gc, GC_MARK(g), g->gc_gen);
+                  g->prio, g->gen, g->last_gc, GC_MARK(g));
         return true;
 }
 
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index a8c57d59a726..926ded8ccbf5 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -635,7 +635,7 @@ static void prio_read(struct cache *ca, uint64_t bucket)
                 }
 
                 b->prio = le16_to_cpu(d->prio);
-                b->gen = b->last_gc = b->gc_gen = d->gen;
+                b->gen = b->last_gc = d->gen;
         }
 }