bcachefs: Tweak bch2_data_update_init() for stack usage

- Separate out a slowpath for bkey_nocow_lock()
- Don't call bch2_bkey_ptrs_c() or loop over pointers more than
  necessary

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

diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c
index c34e5b88ba9d0f19d04312251aacb37995be987f..1216729c20e8f50e08a84bebad6dc16b0b8353d5 100644 (file)
--- a/fs/bcachefs/data_update.c
+++ b/fs/bcachefs/data_update.c
@@ -66,37 +66,46 @@ static void bkey_nocow_unlock(struct bch_fs *c, struct bkey_s_c k)
        }
 }
 
-static bool bkey_nocow_lock(struct bch_fs *c, struct moving_context *ctxt, struct bkey_s_c k)
+static noinline_for_stack
+bool __bkey_nocow_lock(struct bch_fs *c, struct moving_context *ctxt, struct bkey_ptrs_c ptrs,
+                      const struct bch_extent_ptr *start)
 {
-       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+       if (!ctxt) {
+               bkey_for_each_ptr(ptrs, ptr) {
+                       if (ptr == start)
+                               break;
+
+                       struct bch_dev *ca = bch2_dev_have_ref(c, ptr->dev);
+                       struct bpos bucket = PTR_BUCKET_POS(ca, ptr);
+                       bch2_bucket_nocow_unlock(&c->nocow_locks, bucket, 0);
+               }
+               return false;
+       }
 
+       __bkey_for_each_ptr(start, ptrs.end, ptr) {
+               struct bch_dev *ca = bch2_dev_have_ref(c, ptr->dev);
+               struct bpos bucket = PTR_BUCKET_POS(ca, ptr);
+
+               bool locked;
+               move_ctxt_wait_event(ctxt,
+                                    (locked = bch2_bucket_nocow_trylock(&c->nocow_locks, bucket, 0)) ||
+                                    list_empty(&ctxt->ios));
+               if (!locked)
+                       bch2_bucket_nocow_lock(&c->nocow_locks, bucket, 0);
+       }
+       return true;
+}
+
+static bool bkey_nocow_lock(struct bch_fs *c, struct moving_context *ctxt, struct bkey_ptrs_c ptrs)
+{
        bkey_for_each_ptr(ptrs, ptr) {
                struct bch_dev *ca = bch2_dev_have_ref(c, ptr->dev);
                struct bpos bucket = PTR_BUCKET_POS(ca, ptr);
 
-               if (ctxt) {
-                       bool locked;
-
-                       move_ctxt_wait_event(ctxt,
-                               (locked = bch2_bucket_nocow_trylock(&c->nocow_locks, bucket, 0)) ||
-                               list_empty(&ctxt->ios));
-
-                       if (!locked)
-                               bch2_bucket_nocow_lock(&c->nocow_locks, bucket, 0);
-               } else {
-                       if (!bch2_bucket_nocow_trylock(&c->nocow_locks, bucket, 0)) {
-                               bkey_for_each_ptr(ptrs, ptr2) {
-                                       if (ptr2 == ptr)
-                                               break;
-
-                                       ca = bch2_dev_have_ref(c, ptr2->dev);
-                                       bucket = PTR_BUCKET_POS(ca, ptr2);
-                                       bch2_bucket_nocow_unlock(&c->nocow_locks, bucket, 0);
-                               }
-                               return false;
-                       }
-               }
+               if (!bch2_bucket_nocow_trylock(&c->nocow_locks, bucket, 0))
+                       return __bkey_nocow_lock(c, ctxt, ptrs, ptr);
        }
+
        return true;
 }
 
@@ -523,8 +532,9 @@ void bch2_data_update_exit(struct data_update *update)
        bch2_bkey_buf_exit(&update->k, c);
 }
 
-static int bch2_update_unwritten_extent(struct btree_trans *trans,
-                                       struct data_update *update)
+static noinline_for_stack
+int bch2_update_unwritten_extent(struct btree_trans *trans,
+                                struct data_update *update)
 {
        struct bch_fs *c = update->op.c;
        struct bkey_i_extent *e;
@@ -716,18 +726,10 @@ int bch2_extent_drop_ptrs(struct btree_trans *trans,
                bch2_trans_commit(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc);
 }
 
-int bch2_data_update_bios_init(struct data_update *m, struct bch_fs *c,
-                              struct bch_io_opts *io_opts)
+static int __bch2_data_update_bios_init(struct data_update *m, struct bch_fs *c,
+                                       struct bch_io_opts *io_opts,
+                                       unsigned buf_bytes)
 {
-       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(bkey_i_to_s_c(m->k.k));
-       const union bch_extent_entry *entry;
-       struct extent_ptr_decoded p;
-
-       /* write path might have to decompress data: */
-       unsigned buf_bytes = 0;
-       bkey_for_each_ptr_decode(&m->k.k->k, ptrs, p, entry)
-               buf_bytes = max_t(unsigned, buf_bytes, p.crc.uncompressed_size << 9);
-
        unsigned nr_vecs = DIV_ROUND_UP(buf_bytes, PAGE_SIZE);
 
        m->bvecs = kmalloc_array(nr_vecs, sizeof*(m->bvecs), GFP_KERNEL);
@@ -751,6 +753,21 @@ int bch2_data_update_bios_init(struct data_update *m, struct bch_fs *c,
        return 0;
 }
 
+int bch2_data_update_bios_init(struct data_update *m, struct bch_fs *c,
+                              struct bch_io_opts *io_opts)
+{
+       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(bkey_i_to_s_c(m->k.k));
+       const union bch_extent_entry *entry;
+       struct extent_ptr_decoded p;
+
+       /* write path might have to decompress data: */
+       unsigned buf_bytes = 0;
+       bkey_for_each_ptr_decode(&m->k.k->k, ptrs, p, entry)
+               buf_bytes = max_t(unsigned, buf_bytes, p.crc.uncompressed_size << 9);
+
+       return __bch2_data_update_bios_init(m, c, io_opts, buf_bytes);
+}
+
 static int can_write_extent(struct bch_fs *c, struct data_update *m)
 {
        if ((m->op.flags & BCH_WRITE_alloc_nowait) &&
@@ -802,10 +819,6 @@ int bch2_data_update_init(struct btree_trans *trans,
                          struct bkey_s_c k)
 {
        struct bch_fs *c = trans->c;
-       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-       const union bch_extent_entry *entry;
-       struct extent_ptr_decoded p;
-       unsigned reserve_sectors = k.k->size * data_opts.extra_replicas;
        int ret = 0;
 
        /*
@@ -842,6 +855,13 @@ int bch2_data_update_init(struct btree_trans *trans,
 
        unsigned durability_have = 0, durability_removing = 0;
 
+       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(bkey_i_to_s_c(m->k.k));
+       const union bch_extent_entry *entry;
+       struct extent_ptr_decoded p;
+       unsigned reserve_sectors = k.k->size * data_opts.extra_replicas;
+       unsigned buf_bytes = 0;
+       bool unwritten = false;
+
        unsigned ptr_bit = 1;
        bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
                if (!p.ptr.cached) {
@@ -872,6 +892,9 @@ int bch2_data_update_init(struct btree_trans *trans,
                if (p.crc.compression_type == BCH_COMPRESSION_TYPE_incompressible)
                        m->op.incompressible = true;
 
+               buf_bytes = max_t(unsigned, buf_bytes, p.crc.uncompressed_size << 9);
+               unwritten |= p.ptr.unwritten;
+
                ptr_bit <<= 1;
        }
 
@@ -946,18 +969,18 @@ int bch2_data_update_init(struct btree_trans *trans,
        }
 
        if (c->opts.nocow_enabled &&
-           !bkey_nocow_lock(c, ctxt, k)) {
+           !bkey_nocow_lock(c, ctxt, ptrs)) {
                ret = -BCH_ERR_nocow_lock_blocked;
                goto out_put_dev_refs;
        }
 
-       if (bkey_extent_is_unwritten(k)) {
+       if (unwritten) {
                ret = bch2_update_unwritten_extent(trans, m) ?:
                        -BCH_ERR_data_update_done_unwritten;
                goto out_nocow_unlock;
        }
 
-       ret = bch2_data_update_bios_init(m, c, io_opts);
+       ret = __bch2_data_update_bios_init(m, c, io_opts, buf_bytes);
        if (ret)
                goto out_nocow_unlock;