bcachefs: Call bch2_fs_init_rw() early if we'll be going rw

kthread creation checks for pending signals, which is _very_ annoying if
we have to do a long recovery and don't go rw until we've done
significant work.

Check if we'll be going rw and pre-allocate kthreads/workqueues.

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

Author: Kent Overstreet

fs/bcachefs/recovery.c

@@ -762,6 +762,16 @@ int bch2_fs_recovery(struct bch_fs *c)
 		c->opts.fsck = true;
 	}
 
+	if (go_rw_in_recovery(c)) {
+		/*
+		 * start workqueues/kworkers early - kthread creation checks for
+		 * pending signals, which is _very_ annoying
+		 */
+		ret = bch2_fs_init_rw(c);
+		if (ret)
+			goto err;
+	}
+
 	mutex_lock(&c->sb_lock);
 	struct bch_sb_field_ext *ext = bch2_sb_field_get(c->disk_sb.sb, ext);
 	bool write_sb = false;

fs/bcachefs/recovery_passes.c

@@ -217,11 +217,7 @@ static int bch2_set_may_go_rw(struct bch_fs *c)
 
 	set_bit(BCH_FS_may_go_rw, &c->flags);
 
-	if (keys->nr ||
-	    !c->opts.read_only ||
-	    !c->sb.clean ||
-	    c->opts.recovery_passes ||
-	    (c->opts.fsck && !(c->sb.features & BIT_ULL(BCH_FEATURE_no_alloc_info)))) {
+	if (go_rw_in_recovery(c)) {
 		if (c->sb.features & BIT_ULL(BCH_FEATURE_no_alloc_info)) {
 			bch_info(c, "mounting a filesystem with no alloc info read-write; will recreate");
 			bch2_reconstruct_alloc(c);

fs/bcachefs/recovery_passes.h

@@ -17,6 +17,15 @@ enum bch_run_recovery_pass_flags {
 	RUN_RECOVERY_PASS_ratelimit	= BIT(1),
 };
 
+static inline bool go_rw_in_recovery(struct bch_fs *c)
+{
+	return (c->journal_keys.nr ||
+		!c->opts.read_only ||
+		!c->sb.clean ||
+		c->opts.recovery_passes ||
+		(c->opts.fsck && !(c->sb.features & BIT_ULL(BCH_FEATURE_no_alloc_info))));
+}
+
 int bch2_run_print_explicit_recovery_pass(struct bch_fs *, enum bch_recovery_pass);
 
 int __bch2_run_explicit_recovery_pass(struct bch_fs *, struct printbuf *,

fs/bcachefs/super.c

@@ -210,7 +210,6 @@ static int bch2_dev_alloc(struct bch_fs *, unsigned);
 static int bch2_dev_sysfs_online(struct bch_fs *, struct bch_dev *);
 static void bch2_dev_io_ref_stop(struct bch_dev *, int);
 static void __bch2_dev_read_only(struct bch_fs *, struct bch_dev *);
-static int bch2_fs_init_rw(struct bch_fs *);
 
 struct bch_fs *bch2_dev_to_fs(dev_t dev)
 {
@@ -794,7 +793,7 @@ static int bch2_fs_online(struct bch_fs *c)
 	return ret;
 }
 
-static int bch2_fs_init_rw(struct bch_fs *c)
+int bch2_fs_init_rw(struct bch_fs *c)
 {
 	if (test_bit(BCH_FS_rw_init_done, &c->flags))
 		return 0;
@@ -1015,6 +1014,16 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts *opts,
 	if (ret)
 		goto err;
 
+	if (go_rw_in_recovery(c)) {
+		/*
+		 * start workqueues/kworkers early - kthread creation checks for
+		 * pending signals, which is _very_ annoying
+		 */
+		ret = bch2_fs_init_rw(c);
+		if (ret)
+			goto err;
+	}
+
 #ifdef CONFIG_UNICODE
 	/* Default encoding until we can potentially have more as an option. */
 	c->cf_encoding = utf8_load(BCH_FS_DEFAULT_UTF8_ENCODING);

fs/bcachefs/super.h

@@ -46,6 +46,7 @@ void __bch2_fs_stop(struct bch_fs *);
 void bch2_fs_free(struct bch_fs *);
 void bch2_fs_stop(struct bch_fs *);
 
+int bch2_fs_init_rw(struct bch_fs *);
 int bch2_fs_start(struct bch_fs *);
 struct bch_fs *bch2_fs_open(darray_const_str *, struct bch_opts *);