From: Kent Overstreet <kent.overstreet@gmail.com>
Date: Thu, 3 Dec 2020 21:20:18 +0000 (-0500)
Subject: bcachefs: Don't issue btree writes that weren't journalled
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5db43418d5097b8aca5c725eb301186dee04c70a;p=linux.git

bcachefs: Don't issue btree writes that weren't journalled

If we have an error in the btree interior update path that prevents us
from journalling the update, we can't issue the corresponding btree node
write - we didn't get a journal sequence number that would cause it to
be ignored in recovery.

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

diff --git a/fs/bcachefs/btree_io.c b/fs/bcachefs/btree_io.c
index 520eef531d397..b2ffdff48637c 100644
--- a/fs/bcachefs/btree_io.c
+++ b/fs/bcachefs/btree_io.c
@@ -1499,6 +1499,9 @@ void __bch2_btree_node_write(struct bch_fs *c, struct btree *b,
 		if (!btree_node_may_write(b))
 			return;
 
+		if (old & (1 << BTREE_NODE_never_write))
+			return;
+
 		if (old & (1 << BTREE_NODE_write_in_flight)) {
 			btree_node_wait_on_io(b);
 			continue;
@@ -1545,6 +1548,8 @@ void __bch2_btree_node_write(struct bch_fs *c, struct btree *b,
 		seq = max(seq, le64_to_cpu(i->journal_seq));
 	}
 
+	BUG_ON(b->written && !seq);
+
 	/* bch2_varint_decode may read up to 7 bytes past the end of the buffer: */
 	bytes += 8;
 
diff --git a/fs/bcachefs/btree_types.h b/fs/bcachefs/btree_types.h
index d30c31f0f11fd..51ad87abc7638 100644
--- a/fs/bcachefs/btree_types.h
+++ b/fs/bcachefs/btree_types.h
@@ -415,6 +415,7 @@ enum btree_flags {
 	BTREE_NODE_fake,
 	BTREE_NODE_old_extent_overwrite,
 	BTREE_NODE_need_rewrite,
+	BTREE_NODE_never_write,
 };
 
 BTREE_FLAG(read_in_flight);
@@ -429,6 +430,7 @@ BTREE_FLAG(dying);
 BTREE_FLAG(fake);
 BTREE_FLAG(old_extent_overwrite);
 BTREE_FLAG(need_rewrite);
+BTREE_FLAG(never_write);
 
 static inline struct btree_write *btree_current_write(struct btree *b)
 {
diff --git a/fs/bcachefs/btree_update_interior.c b/fs/bcachefs/btree_update_interior.c
index aed54d5b5251e..594bcd7975169 100644
--- a/fs/bcachefs/btree_update_interior.c
+++ b/fs/bcachefs/btree_update_interior.c
@@ -603,17 +603,30 @@ err:
 
 		list_del(&as->write_blocked_list);
 
-		if (!ret && as->b == b) {
+		/*
+		 * Node might have been freed, recheck under
+		 * btree_interior_update_lock:
+		 */
+		if (as->b == b) {
 			struct bset *i = btree_bset_last(b);
 
 			BUG_ON(!b->c.level);
 			BUG_ON(!btree_node_dirty(b));
 
-			i->journal_seq = cpu_to_le64(
-				max(journal_seq,
-				    le64_to_cpu(i->journal_seq)));
-
-			bch2_btree_add_journal_pin(c, b, journal_seq);
+			if (!ret) {
+				i->journal_seq = cpu_to_le64(
+					max(journal_seq,
+					    le64_to_cpu(i->journal_seq)));
+
+				bch2_btree_add_journal_pin(c, b, journal_seq);
+			} else {
+				/*
+				 * If we didn't get a journal sequence number we
+				 * can't write this btree node, because recovery
+				 * won't know to ignore this write:
+				 */
+				set_btree_node_never_write(b);
+			}
 		}
 
 		mutex_unlock(&c->btree_interior_update_lock);