bcachefs: Add an option to control btree node prefetching

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

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 7e5c797cfaf240e0258259cddae26bdb8bb3fcef..fa298289e01656b989db38dcf19301ae4d880bb7 100644 (file)
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -897,7 +897,8 @@ static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
 
        bch2_bkey_buf_reassemble(out, c, k);
 
-       if (flags & BTREE_ITER_PREFETCH)
+       if ((flags & BTREE_ITER_PREFETCH) &&
+           c->opts.btree_node_prefetch)
                ret = btree_path_prefetch_j(trans, path, &jiter);
 
        bch2_btree_and_journal_iter_exit(&jiter);
@@ -929,7 +930,8 @@ static __always_inline int btree_path_down(struct btree_trans *trans,
                bch2_bkey_buf_unpack(&tmp, c, l->b,
                                 bch2_btree_node_iter_peek(&l->iter, l->b));
 
-               if (flags & BTREE_ITER_PREFETCH) {
+               if ((flags & BTREE_ITER_PREFETCH) &&
+                   c->opts.btree_node_prefetch) {
                        ret = btree_path_prefetch(trans, path);
                        if (ret)
                                goto err;

diff --git a/fs/bcachefs/opts.h b/fs/bcachefs/opts.h
index a6f5185ecd67e58d446f221b4dcab3704e6edaa9..93a24fef42148488cdddb391cd291dd0e0168063 100644 (file)
--- a/fs/bcachefs/opts.h
+++ b/fs/bcachefs/opts.h
@@ -458,7 +458,13 @@ enum fsck_err_opts {
          OPT_UINT(0, BCH_REPLICAS_MAX),                                \
          BCH2_NO_SB_OPT,               1,                              \
          "n",          "Data written to this device will be considered\n"\
-                       "to have already been replicated n times")
+                       "to have already been replicated n times")      \
+       x(btree_node_prefetch,          u8,                             \
+         OPT_FS|OPT_MOUNT|OPT_RUNTIME,                                 \
+         OPT_BOOL(),                                                   \
+         BCH2_NO_SB_OPT,               true,                           \
+         NULL,         "BTREE_ITER_PREFETCH casuse btree nodes to be\n"\
+         " prefetched sequentially")
 
 struct bch_opts {
 #define x(_name, _bits, ...)   unsigned _name##_defined:1;