bcachefs: Rework init order in bch2_data_update_init()

Initialize the write op first, so that in the next patch we can check if
the allocator would block (for BCH_WRITE_alloc_nowait ops) and bail out
before taking nocow locks/dev refs.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c
index 5873abf0a0b25dcea83d43b28e3060db8c3dbded..3e8ad94dca590041eec0abf24266277db1a31817 100644 (file)
--- a/fs/bcachefs/data_update.c
+++ b/fs/bcachefs/data_update.c
@@ -35,7 +35,7 @@ static bool bkey_get_dev_refs(struct bch_fs *c, struct bkey_s_c k)
        struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
 
        bkey_for_each_ptr(ptrs, ptr) {
-               if (!bch2_dev_tryget(c, ptr->dev)) {
+               if (unlikely(!bch2_dev_tryget(c, ptr->dev))) {
                        bkey_for_each_ptr(ptrs, ptr2) {
                                if (ptr2 == ptr)
                                        break;
@@ -449,14 +449,15 @@ void bch2_data_update_exit(struct data_update *update)
        struct bch_fs *c = update->op.c;
        struct bkey_s_c k = bkey_i_to_s_c(update->k.k);
 
+       bch2_bio_free_pages_pool(c, &update->op.wbio.bio);
+       kfree(update->bvecs);
+       update->bvecs = NULL;
+
        if (c->opts.nocow_enabled)
                bkey_nocow_unlock(c, k);
        bkey_put_dev_refs(c, k);
-       bch2_bkey_buf_exit(&update->k, c);
        bch2_disk_reservation_put(c, &update->op.res);
-       bch2_bio_free_pages_pool(c, &update->op.wbio.bio);
-       kfree(update->bvecs);
-       update->bvecs = NULL;
+       bch2_bkey_buf_exit(&update->k, c);
 }
 
 static int bch2_update_unwritten_extent(struct btree_trans *trans,
@@ -663,15 +664,6 @@ int bch2_data_update_init(struct btree_trans *trans,
        if (unlikely(k.k->p.snapshot && !bch2_snapshot_exists(c, k.k->p.snapshot)))
                return -BCH_ERR_data_update_done_no_snapshot;
 
-       if (!bkey_get_dev_refs(c, k))
-               return -BCH_ERR_data_update_done_no_dev_refs;
-
-       if (c->opts.nocow_enabled &&
-           !bkey_nocow_lock(c, ctxt, k)) {
-               bkey_put_dev_refs(c, k);
-               return -BCH_ERR_nocow_lock_blocked;
-       }
-
        bch2_bkey_buf_init(&m->k);
        bch2_bkey_buf_reassemble(&m->k, c, k);
        m->btree_id     = btree_id;
@@ -764,7 +756,7 @@ int bch2_data_update_init(struct btree_trans *trans,
                        ret = bch2_extent_drop_ptrs(trans, iter, k, &io_opts, &m->data_opts);
                if (!ret)
                        ret = -BCH_ERR_data_update_done_no_writes_needed;
-               goto out;
+               goto out_bkey_buf_exit;
        }
 
        if (reserve_sectors) {
@@ -773,13 +765,24 @@ int bch2_data_update_init(struct btree_trans *trans,
                                ? 0
                                : BCH_DISK_RESERVATION_NOFAIL);
                if (ret)
-                       goto out;
+                       goto out_bkey_buf_exit;
+       }
+
+       if (!bkey_get_dev_refs(c, k)) {
+               ret = -BCH_ERR_data_update_done_no_dev_refs;
+               goto out_put_disk_res;
+       }
+
+       if (c->opts.nocow_enabled &&
+           !bkey_nocow_lock(c, ctxt, k)) {
+               ret = -BCH_ERR_nocow_lock_blocked;
+               goto out_put_dev_refs;
        }
 
        if (bkey_extent_is_unwritten(k)) {
                ret = bch2_update_unwritten_extent(trans, m) ?:
                        -BCH_ERR_data_update_done_unwritten;
-               goto out;
+               goto out_nocow_unlock;
        }
 
        /* write path might have to decompress data: */
@@ -807,9 +810,18 @@ int bch2_data_update_init(struct btree_trans *trans,
        return 0;
 enomem:
        ret = -ENOMEM;
-out:
-       bch2_data_update_exit(m);
-       return ret ?: -BCH_ERR_data_update_done;
+       kfree(m->bvecs);
+       m->bvecs = NULL;
+out_nocow_unlock:
+       if (c->opts.nocow_enabled)
+               bkey_nocow_unlock(c, k);
+out_put_dev_refs:
+       bkey_put_dev_refs(c, k);
+out_put_disk_res:
+       bch2_disk_reservation_put(c, &m->op.res);
+out_bkey_buf_exit:
+       bch2_bkey_buf_exit(&m->k, c);
+       return ret;
 }
 
 void bch2_data_update_opts_normalize(struct bkey_s_c k, struct data_update_opts *opts)