bcachefs: Rhashtable based buckets_in_flight for copygc
authorKent Overstreet <kent.overstreet@linux.dev>
Sat, 11 Mar 2023 19:44:41 +0000 (14:44 -0500)
committerKent Overstreet <kent.overstreet@linux.dev>
Sun, 22 Oct 2023 21:09:58 +0000 (17:09 -0400)
Previously, copygc used a fifo for tracking buckets in flight - this had
the disadvantage of being fixed size, since we pass references to
elements into the move code.

This restructures it to be a hash table and linked list, since with
erasure coding we need to be able to pipeline across an arbitrary number
of buckets.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
fs/bcachefs/move_types.h
fs/bcachefs/movinggc.c

index 285ffdb762aca17ab9769ca2ab36b7e404c2dd3e..baf1f8570b3fe05f1733ae9be1cfa28c9e3db933 100644 (file)
@@ -16,9 +16,20 @@ struct bch_move_stats {
        atomic64_t              sectors_raced;
 };
 
-struct move_bucket_in_flight {
+struct move_bucket_key {
        struct bpos             bucket;
        u8                      gen;
+};
+
+struct move_bucket {
+       struct move_bucket_key  k;
+       unsigned                sectors;
+};
+
+struct move_bucket_in_flight {
+       struct move_bucket_in_flight *next;
+       struct rhash_head       hash;
+       struct move_bucket      bucket;
        atomic_t                count;
 };
 
index e91067b428cd8eb9357d9558e21a9f990a4f82ca..2d75334c541dd78960f696d4af5c9e17095da947 100644 (file)
 #include <linux/sort.h>
 #include <linux/wait.h>
 
+struct buckets_in_flight {
+       struct rhashtable               table;
+       struct move_bucket_in_flight    *first;
+       struct move_bucket_in_flight    *last;
+       size_t                          nr;
+       size_t                          sectors;
+};
+
+static const struct rhashtable_params bch_move_bucket_params = {
+       .head_offset    = offsetof(struct move_bucket_in_flight, hash),
+       .key_offset     = offsetof(struct move_bucket_in_flight, bucket.k),
+       .key_len        = sizeof(struct move_bucket_key),
+};
+
+static struct move_bucket_in_flight *
+move_bucket_in_flight_add(struct buckets_in_flight *list, struct move_bucket b)
+{
+       struct move_bucket_in_flight *new = kzalloc(sizeof(*new), GFP_KERNEL);
+       int ret;
+
+       if (!new)
+               return ERR_PTR(-ENOMEM);
+
+       new->bucket = b;
+
+       ret = rhashtable_lookup_insert_fast(&list->table, &new->hash,
+                                           bch_move_bucket_params);
+       if (ret) {
+               kfree(new);
+               return ERR_PTR(ret);
+       }
+
+       if (!list->first)
+               list->first = new;
+       else
+               list->last->next = new;
+
+       list->last = new;
+       list->nr++;
+       list->sectors += b.sectors;
+       return new;
+}
+
 static int bch2_bucket_is_movable(struct btree_trans *trans,
-                                 struct bpos bucket, u64 time, u8 *gen)
+                                 struct move_bucket *b, u64 time)
 {
        struct btree_iter iter;
        struct bkey_s_c k;
@@ -43,10 +86,13 @@ static int bch2_bucket_is_movable(struct btree_trans *trans,
        const struct bch_alloc_v4 *a;
        int ret;
 
-       if (bch2_bucket_is_open(trans->c, bucket.inode, bucket.offset))
+       if (bch2_bucket_is_open(trans->c,
+                               b->k.bucket.inode,
+                               b->k.bucket.offset))
                return 0;
 
-       bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc, bucket, BTREE_ITER_CACHED);
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
+                            b->k.bucket, BTREE_ITER_CACHED);
        k = bch2_btree_iter_peek_slot(&iter);
        ret = bkey_err(k);
        bch2_trans_iter_exit(trans, &iter);
@@ -55,12 +101,14 @@ static int bch2_bucket_is_movable(struct btree_trans *trans,
                return ret;
 
        a = bch2_alloc_to_v4(k, &_a);
-       *gen = a->gen;
+       b->k.gen        = a->gen;
+       b->sectors      = a->dirty_sectors;
+
        ret = data_type_movable(a->data_type) &&
                a->fragmentation_lru &&
                a->fragmentation_lru <= time;
 
-       if (ret) {
+       if (!ret) {
                struct printbuf buf = PRINTBUF;
 
                bch2_bkey_val_to_text(&buf, trans->c, k);
@@ -71,41 +119,16 @@ static int bch2_bucket_is_movable(struct btree_trans *trans,
        return ret;
 }
 
-typedef FIFO(struct move_bucket_in_flight) move_buckets_in_flight;
-
-struct move_bucket {
-       struct bpos             bucket;
-       u8                      gen;
-};
-
-typedef DARRAY(struct move_bucket) move_buckets;
-
-static int move_bucket_cmp(const void *_l, const void *_r)
-{
-       const struct move_bucket *l = _l;
-       const struct move_bucket *r = _r;
-
-       return bkey_cmp(l->bucket, r->bucket);
-}
-
-static bool bucket_in_flight(move_buckets *buckets_sorted, struct move_bucket b)
-{
-       return bsearch(&b,
-                      buckets_sorted->data,
-                      buckets_sorted->nr,
-                      sizeof(buckets_sorted->data[0]),
-                      move_bucket_cmp) != NULL;
-}
-
 static void move_buckets_wait(struct btree_trans *trans,
                              struct moving_context *ctxt,
-                             move_buckets_in_flight *buckets_in_flight,
-                             size_t nr, bool verify_evacuated)
+                             struct buckets_in_flight *list,
+                             bool flush)
 {
-       while (!fifo_empty(buckets_in_flight)) {
-               struct move_bucket_in_flight *i = &fifo_peek_front(buckets_in_flight);
+       struct move_bucket_in_flight *i;
+       int ret;
 
-               if (fifo_used(buckets_in_flight) > nr)
+       while ((i = list->first)) {
+               if (flush)
                        move_ctxt_wait_event(ctxt, trans, !atomic_read(&i->count));
 
                if (atomic_read(&i->count))
@@ -116,66 +139,82 @@ static void move_buckets_wait(struct btree_trans *trans,
                 * reads, which inits another btree_trans; this one must be
                 * unlocked:
                 */
-               if (verify_evacuated)
-                       bch2_verify_bucket_evacuated(trans, i->bucket, i->gen);
-               buckets_in_flight->front++;
+               bch2_verify_bucket_evacuated(trans, i->bucket.k.bucket, i->bucket.k.gen);
+
+               list->first = i->next;
+               if (!list->first)
+                       list->last = NULL;
+
+               list->nr--;
+               list->sectors -= i->bucket.sectors;
+
+               ret = rhashtable_remove_fast(&list->table, &i->hash,
+                                            bch_move_bucket_params);
+               BUG_ON(ret);
+               kfree(i);
        }
 
        bch2_trans_unlock(trans);
 }
 
+static bool bucket_in_flight(struct buckets_in_flight *list,
+                            struct move_bucket_key k)
+{
+       return rhashtable_lookup_fast(&list->table, &k, bch_move_bucket_params);
+}
+
+typedef DARRAY(struct move_bucket) move_buckets;
+
 static int bch2_copygc_get_buckets(struct btree_trans *trans,
                        struct moving_context *ctxt,
-                       move_buckets_in_flight *buckets_in_flight,
+                       struct buckets_in_flight *buckets_in_flight,
                        move_buckets *buckets)
 {
+       struct bch_fs *c = trans->c;
        struct btree_iter iter;
-       move_buckets buckets_sorted = { 0 };
-       struct move_bucket_in_flight *i;
        struct bkey_s_c k;
-       size_t fifo_iter, nr_to_get;
+       size_t nr_to_get = max(16UL, buckets_in_flight->nr / 4);
+       size_t saw = 0, in_flight = 0, not_movable = 0, sectors = 0;
        int ret;
 
-       move_buckets_wait(trans, ctxt, buckets_in_flight, buckets_in_flight->size / 2, true);
+       move_buckets_wait(trans, ctxt, buckets_in_flight, false);
 
-       nr_to_get = max(16UL, fifo_used(buckets_in_flight) / 4);
-
-       fifo_for_each_entry_ptr(i, buckets_in_flight, fifo_iter) {
-               ret = darray_push(&buckets_sorted, ((struct move_bucket) {i->bucket, i->gen}));
-               if (ret) {
-                       bch_err(trans->c, "error allocating move_buckets_sorted");
-                       goto err;
-               }
-       }
-
-       sort(buckets_sorted.data,
-            buckets_sorted.nr,
-            sizeof(buckets_sorted.data[0]),
-            move_bucket_cmp,
-            NULL);
+       ret = bch2_btree_write_buffer_flush(trans);
+       if (bch2_fs_fatal_err_on(ret, c, "%s: error %s from bch2_btree_write_buffer_flush()",
+                                __func__, bch2_err_str(ret)))
+               return ret;
 
        ret = for_each_btree_key2_upto(trans, iter, BTREE_ID_lru,
                                  lru_pos(BCH_LRU_FRAGMENTATION_START, 0, 0),
                                  lru_pos(BCH_LRU_FRAGMENTATION_START, U64_MAX, LRU_TIME_MAX),
                                  0, k, ({
-               struct move_bucket b = { .bucket = u64_to_bucket(k.k->p.offset) };
+               struct move_bucket b = { .k.bucket = u64_to_bucket(k.k->p.offset) };
                int ret = 0;
 
-               if (!bucket_in_flight(&buckets_sorted, b) &&
-                   bch2_bucket_is_movable(trans, b.bucket, lru_pos_time(k.k->p), &b.gen))
-                       ret = darray_push(buckets, b) ?: buckets->nr >= nr_to_get;
+               saw++;
 
+               if (!bch2_bucket_is_movable(trans, &b, lru_pos_time(k.k->p)))
+                       not_movable++;
+               else if (bucket_in_flight(buckets_in_flight, b.k))
+                       in_flight++;
+               else {
+                       ret = darray_push(buckets, b) ?: buckets->nr >= nr_to_get;
+                       if (ret >= 0)
+                               sectors += b.sectors;
+               }
                ret;
        }));
-err:
-       darray_exit(&buckets_sorted);
+
+       pr_debug("have: %zu (%zu) saw %zu in flight %zu not movable %zu got %zu (%zu)/%zu buckets ret %i",
+                buckets_in_flight->nr, buckets_in_flight->sectors,
+                saw, in_flight, not_movable, buckets->nr, sectors, nr_to_get, ret);
 
        return ret < 0 ? ret : 0;
 }
 
 static int bch2_copygc(struct btree_trans *trans,
                       struct moving_context *ctxt,
-                      move_buckets_in_flight *buckets_in_flight)
+                      struct buckets_in_flight *buckets_in_flight)
 {
        struct bch_fs *c = trans->c;
        struct data_update_opts data_opts = {
@@ -187,11 +226,6 @@ static int bch2_copygc(struct btree_trans *trans,
        u64 moved = atomic64_read(&ctxt->stats->sectors_moved);
        int ret = 0;
 
-       ret = bch2_btree_write_buffer_flush(trans);
-       if (bch2_fs_fatal_err_on(ret, c, "%s: error %s from bch2_btree_write_buffer_flush()",
-                                __func__, bch2_err_str(ret)))
-               return ret;
-
        ret = bch2_copygc_get_buckets(trans, ctxt, buckets_in_flight, &buckets);
        if (ret)
                goto err;
@@ -200,12 +234,17 @@ static int bch2_copygc(struct btree_trans *trans,
                if (unlikely(freezing(current)))
                        break;
 
-               f = fifo_push_ref(buckets_in_flight);
-               f->bucket       = i->bucket;
-               f->gen          = i->gen;
-               atomic_set(&f->count, 0);
+               f = move_bucket_in_flight_add(buckets_in_flight, *i);
+               ret = PTR_ERR_OR_ZERO(f);
+               if (ret == -EEXIST) /* rare race: copygc_get_buckets returned same bucket more than once */
+                       continue;
+               if (ret == -ENOMEM) { /* flush IO, continue later */
+                       ret = 0;
+                       break;
+               }
 
-               ret = __bch2_evacuate_bucket(trans, ctxt, f, f->bucket, f->gen, data_opts);
+               ret = __bch2_evacuate_bucket(trans, ctxt, f, f->bucket.k.bucket,
+                                            f->bucket.k.gen, data_opts);
                if (ret)
                        goto err;
        }
@@ -287,13 +326,17 @@ static int bch2_copygc_thread(void *arg)
        struct moving_context ctxt;
        struct bch_move_stats move_stats;
        struct io_clock *clock = &c->io_clock[WRITE];
-       move_buckets_in_flight move_buckets;
+       struct buckets_in_flight move_buckets;
        u64 last, wait;
        int ret = 0;
 
-       if (!init_fifo(&move_buckets, 1 << 14, GFP_KERNEL)) {
-               bch_err(c, "error allocating copygc buckets in flight");
-               return -ENOMEM;
+       memset(&move_buckets, 0, sizeof(move_buckets));
+
+       ret = rhashtable_init(&move_buckets.table, &bch_move_bucket_params);
+       if (ret) {
+               bch_err(c, "error allocating copygc buckets in flight: %s",
+                       bch2_err_str(ret));
+               return ret;
        }
 
        set_freezable();
@@ -309,12 +352,12 @@ static int bch2_copygc_thread(void *arg)
                cond_resched();
 
                if (!c->copy_gc_enabled) {
-                       move_buckets_wait(&trans, &ctxt, &move_buckets, 0, true);
+                       move_buckets_wait(&trans, &ctxt, &move_buckets, true);
                        kthread_wait_freezable(c->copy_gc_enabled);
                }
 
                if (unlikely(freezing(current))) {
-                       move_buckets_wait(&trans, &ctxt, &move_buckets, 0, true);
+                       move_buckets_wait(&trans, &ctxt, &move_buckets, true);
                        __refrigerator(false);
                        continue;
                }
@@ -325,8 +368,7 @@ static int bch2_copygc_thread(void *arg)
                if (wait > clock->max_slop) {
                        c->copygc_wait_at = last;
                        c->copygc_wait = last + wait;
-
-                       move_buckets_wait(&trans, &ctxt, &move_buckets, 0, true);
+                       move_buckets_wait(&trans, &ctxt, &move_buckets, true);
                        trace_and_count(c, copygc_wait, c, wait, last + wait);
                        bch2_kthread_io_clock_wait(clock, last + wait,
                                        MAX_SCHEDULE_TIMEOUT);
@@ -342,9 +384,9 @@ static int bch2_copygc_thread(void *arg)
                wake_up(&c->copygc_running_wq);
        }
 
+       move_buckets_wait(&trans, &ctxt, &move_buckets, true);
        bch2_trans_exit(&trans);
        bch2_moving_ctxt_exit(&ctxt);
-       free_fifo(&move_buckets);
 
        return 0;
 }