bcachefs: bch2_run_online_recovery_passes()

Add a new helper for running online recovery passes - i.e. online fsck.
This is a subset of our normal recovery passes, and does not - for now -
use or follow c->curr_recovery_pass.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs.h

@@ -1047,6 +1047,13 @@ struct bch_fs {
 	/* RECOVERY */
 	u64			journal_replay_seq_start;
 	u64			journal_replay_seq_end;
+	/*
+	 * Two different uses:
+	 * "Has this fsck pass?" - i.e. should this type of error be an
+	 * emergency read-only
+	 * And, in certain situations fsck will rewind to an earlier pass: used
+	 * for signaling to the toplevel code which pass we want to run now.
+	 */
 	enum bch_recovery_pass	curr_recovery_pass;
 	/* bitmap of explicitly enabled recovery passes: */
 	u64			recovery_passes_explicit;

fs/bcachefs/recovery.c

@@ -665,7 +665,7 @@ u64 bch2_fsck_recovery_passes(void)
 
 static bool should_run_recovery_pass(struct bch_fs *c, enum bch_recovery_pass pass)
 {
-	struct recovery_pass_fn *p = recovery_pass_fns + c->curr_recovery_pass;
+	struct recovery_pass_fn *p = recovery_pass_fns + pass;
 
 	if (c->opts.norecovery && pass > BCH_RECOVERY_PASS_snapshots_read)
 		return false;
@@ -682,39 +682,58 @@ static bool should_run_recovery_pass(struct bch_fs *c, enum bch_recovery_pass pa
 
 static int bch2_run_recovery_pass(struct bch_fs *c, enum bch_recovery_pass pass)
 {
+	struct recovery_pass_fn *p = recovery_pass_fns + pass;
 	int ret;
 
-	c->curr_recovery_pass = pass;
+	if (!(p->when & PASS_SILENT))
+		bch2_print(c, KERN_INFO bch2_log_msg(c, "%s..."),
+			   bch2_recovery_passes[pass]);
+	ret = p->fn(c);
+	if (ret)
+		return ret;
+	if (!(p->when & PASS_SILENT))
+		bch2_print(c, KERN_CONT " done\n");
 
-	if (should_run_recovery_pass(c, pass)) {
-		struct recovery_pass_fn *p = recovery_pass_fns + pass;
+	return 0;
+}
 
-		if (!(p->when & PASS_SILENT))
-			bch2_print(c, KERN_INFO bch2_log_msg(c, "%s..."),
-				   bch2_recovery_passes[pass]);
-		ret = p->fn(c);
-		if (ret)
-			return ret;
-		if (!(p->when & PASS_SILENT))
-			bch2_print(c, KERN_CONT " done\n");
+static int bch2_run_recovery_passes(struct bch_fs *c)
+{
+	int ret = 0;
+
+	while (c->curr_recovery_pass < ARRAY_SIZE(recovery_pass_fns)) {
+		if (should_run_recovery_pass(c, c->curr_recovery_pass)) {
+			ret = bch2_run_recovery_pass(c, c->curr_recovery_pass);
+			if (bch2_err_matches(ret, BCH_ERR_restart_recovery))
+				continue;
+			if (ret)
+				break;
 
-		c->recovery_passes_complete |= BIT_ULL(pass);
+			c->recovery_passes_complete |= BIT_ULL(c->curr_recovery_pass);
+		}
+		c->curr_recovery_pass++;
 	}
 
-	return 0;
+	return ret;
 }
 
-static int bch2_run_recovery_passes(struct bch_fs *c)
+int bch2_run_online_recovery_passes(struct bch_fs *c)
 {
 	int ret = 0;
 
-	while (c->curr_recovery_pass < ARRAY_SIZE(recovery_pass_fns)) {
-		ret = bch2_run_recovery_pass(c, c->curr_recovery_pass);
-		if (bch2_err_matches(ret, BCH_ERR_restart_recovery))
+	for (unsigned i = 0; i < ARRAY_SIZE(recovery_pass_fns); i++) {
+		struct recovery_pass_fn *p = recovery_pass_fns + i;
+
+		if (!(p->when & PASS_ONLINE))
+			continue;
+
+		ret = bch2_run_recovery_pass(c, i);
+		if (bch2_err_matches(ret, BCH_ERR_restart_recovery)) {
+			i = c->curr_recovery_pass;
 			continue;
+		}
 		if (ret)
 			break;
-		c->curr_recovery_pass++;
 	}
 
 	return ret;

fs/bcachefs/recovery.h

@@ -31,6 +31,7 @@ static inline int bch2_run_explicit_recovery_pass(struct bch_fs *c,
 	}
 }
 
+int bch2_run_online_recovery_passes(struct bch_fs *);
 u64 bch2_fsck_recovery_passes(void);
 
 int bch2_fs_recovery(struct bch_fs *);