bcachefs: BCH_RECOVERY_PASS_NO_RATELIMIT

Add a superblock flag to temporarily disable ratelimiting for a recovery
pass.

This will be used to make check_key_has_snapshot safer: we don't want to
delete a key for a missing snapshot unless we know that the snapshots
and subvolumes btrees are consistent, i.e. check_snapshots and
check_subvols have run recently.

Changing those btrees - creating/deleting a subvolume or snapshot - will
set the "disable ratelimit" flag, i.e. ensuring that those passes run if
check_key_has_snapshot discovers an error.

We're only disabling ratelimiting in the snapshot/subvol delete paths,
we're not so concerned about the create paths.

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

fs/bcachefs/recovery_passes.c

@@ -103,20 +103,20 @@ static void bch2_sb_recovery_passes_to_text(struct printbuf *out,
 		prt_tab(out);
 
 		bch2_pr_time_units(out, le32_to_cpu(i->last_runtime) * NSEC_PER_SEC);
+
+		if (BCH_RECOVERY_PASS_NO_RATELIMIT(i))
+			prt_str(out, " (no ratelimit)");
+
 		prt_newline(out);
 	}
 }
 
-static void bch2_sb_recovery_pass_complete(struct bch_fs *c,
+static struct recovery_pass_entry *bch2_sb_recovery_pass_entry(struct bch_fs *c,
-					   enum bch_recovery_pass pass,
+							       enum bch_recovery_pass pass)
-					   s64 start_time)
 {
 	enum bch_recovery_pass_stable stable = bch2_recovery_pass_to_stable(pass);
-	s64 end_time = ktime_get_real_seconds();
 
-	mutex_lock(&c->sb_lock);
+	lockdep_assert_held(&c->sb_lock);
-	struct bch_sb_field_ext *ext = bch2_sb_field_get(c->disk_sb.sb, ext);
-	__clear_bit_le64(stable, ext->recovery_passes_required);
 
 	struct bch_sb_field_recovery_passes *r =
 		bch2_sb_field_get(c->disk_sb.sb, recovery_passes);
@@ -127,15 +127,43 @@ static void bch2_sb_recovery_pass_complete(struct bch_fs *c,
 		r = bch2_sb_field_resize(&c->disk_sb, recovery_passes, u64s);
 		if (!r) {
 			bch_err(c, "error creating recovery_passes sb section");
-			goto out;
+			return NULL;
 		}
 	}
 
-	r->start[stable].last_run	= cpu_to_le64(end_time);
+	return r->start + stable;
-	r->start[stable].last_runtime	= cpu_to_le32(max(0, end_time - start_time));
+}
-out:
+
+static void bch2_sb_recovery_pass_complete(struct bch_fs *c,
+					   enum bch_recovery_pass pass,
+					   s64 start_time)
+{
+	guard(mutex)(&c->sb_lock);
+	struct bch_sb_field_ext *ext = bch2_sb_field_get(c->disk_sb.sb, ext);
+	__clear_bit_le64(bch2_recovery_pass_to_stable(pass),
+			 ext->recovery_passes_required);
+
+	struct recovery_pass_entry *e = bch2_sb_recovery_pass_entry(c, pass);
+	if (e) {
+		s64 end_time	= ktime_get_real_seconds();
+		e->last_run	= cpu_to_le64(end_time);
+		e->last_runtime	= cpu_to_le32(max(0, end_time - start_time));
+		SET_BCH_RECOVERY_PASS_NO_RATELIMIT(e, false);
+	}
+
 	bch2_write_super(c);
-	mutex_unlock(&c->sb_lock);
+}
+
+void bch2_recovery_pass_set_no_ratelimit(struct bch_fs *c,
+					 enum bch_recovery_pass pass)
+{
+	guard(mutex)(&c->sb_lock);
+
+	struct recovery_pass_entry *e = bch2_sb_recovery_pass_entry(c, pass);
+	if (e && !BCH_RECOVERY_PASS_NO_RATELIMIT(e)) {
+		SET_BCH_RECOVERY_PASS_NO_RATELIMIT(e, false);
+		bch2_write_super(c);
+	}
 }
 
 static bool bch2_recovery_pass_want_ratelimit(struct bch_fs *c, enum bch_recovery_pass pass)
@@ -157,6 +185,9 @@ static bool bch2_recovery_pass_want_ratelimit(struct bch_fs *c, enum bch_recover
 		 */
 		ret = (u64) le32_to_cpu(i->last_runtime) * 100 >
 			ktime_get_real_seconds() - le64_to_cpu(i->last_run);
+
+		if (BCH_RECOVERY_PASS_NO_RATELIMIT(i))
+			ret = false;
 	}
 
 	return ret;

fs/bcachefs/recovery_passes.h

@@ -10,6 +10,8 @@ u64 bch2_recovery_passes_from_stable(u64 v);
 
 u64 bch2_fsck_recovery_passes(void);
 
+void bch2_recovery_pass_set_no_ratelimit(struct bch_fs *, enum bch_recovery_pass);
+
 enum bch_run_recovery_pass_flags {
 	RUN_RECOVERY_PASS_nopersistent	= BIT(0),
 	RUN_RECOVERY_PASS_ratelimit	= BIT(1),

fs/bcachefs/recovery_passes_format.h

@@ -87,6 +87,8 @@ struct recovery_pass_entry {
 	__le32			flags;
 };
 
+LE32_BITMASK(BCH_RECOVERY_PASS_NO_RATELIMIT,	struct recovery_pass_entry, flags, 0, 1)
+
 struct bch_sb_field_recovery_passes {
 	struct bch_sb_field	field;
 	struct recovery_pass_entry start[];

fs/bcachefs/snapshot.c

@@ -1878,6 +1878,8 @@ int __bch2_delete_dead_snapshots(struct bch_fs *c)
 	d->running = false;
 	mutex_unlock(&d->progress_lock);
 	bch2_trans_put(trans);
+
+	bch2_recovery_pass_set_no_ratelimit(c, BCH_RECOVERY_PASS_check_snapshots);
 out_unlock:
 	mutex_unlock(&d->lock);
 	if (!bch2_err_matches(ret, EROFS))

fs/bcachefs/subvolume.c

@@ -482,9 +482,12 @@ static int __bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
 
 static int bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
 {
-	return bch2_subvolumes_reparent(trans, subvolid) ?:
+	int ret = bch2_subvolumes_reparent(trans, subvolid) ?:
 		commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
 			  __bch2_subvolume_delete(trans, subvolid));
+
+	bch2_recovery_pass_set_no_ratelimit(trans->c, BCH_RECOVERY_PASS_check_subvols);
+	return ret;
 }
 
 static void bch2_subvolume_wait_for_pagecache_and_delete(struct work_struct *work)