bcachefs: Get ref on c->writes in move.c

There's no point reading an extent in order to move it if the write is
going to fail because we're shutting down. This patch changes the move
path so that moving_io now owns a ref on c->writes - as a bonus,
rebalance and copygc will now notice that we're shutting down and exit
quicker.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
index a19c3117f9fe..eae93c65e1c7 100644
--- a/fs/bcachefs/move.c
+++ b/fs/bcachefs/move.c
@@ -52,9 +52,11 @@ struct moving_io {
 static void move_free(struct moving_io *io)
 {
 	struct moving_context *ctxt = io->write.ctxt;
+	struct bch_fs *c = ctxt->c;
 
 	bch2_data_update_exit(&io->write);
 	wake_up(&ctxt->wait);
+	percpu_ref_put(&c->writes);
 	kfree(io);
 }
 
@@ -192,6 +194,9 @@ static int bch2_move_extent(struct btree_trans *trans,
 	unsigned sectors = k.k->size, pages;
 	int ret = -ENOMEM;
 
+	if (!percpu_ref_tryget_live(&c->writes))
+		return -EROFS;
+
 	/* write path might have to decompress data: */
 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
 		sectors = max_t(unsigned, sectors, p.crc.uncompressed_size);
@@ -258,6 +263,7 @@ err_free_pages:
 err_free:
 	kfree(io);
 err:
+	percpu_ref_put(&c->writes);
 	trace_move_alloc_mem_fail(k.k);
 	return ret;
 }