bcachefs: Fix a bug with the journal_seq_blacklist mechanism

Previously, we would start doing btree updates before writing the first
journal entry; if this was after an unclean shutdown, this could cause
those btree updates to not be blacklisted.

Also, move some code to headers for userspace debug tools.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_io.c

@@ -597,34 +597,6 @@ void bch2_btree_init_next(struct bch_fs *c, struct btree *b,
 		bch2_btree_iter_reinit_node(iter, b);
 }
 
-static struct nonce btree_nonce(struct bset *i, unsigned offset)
-{
-	return (struct nonce) {{
-		[0] = cpu_to_le32(offset),
-		[1] = ((__le32 *) &i->seq)[0],
-		[2] = ((__le32 *) &i->seq)[1],
-		[3] = ((__le32 *) &i->journal_seq)[0]^BCH_NONCE_BTREE,
-	}};
-}
-
-static void bset_encrypt(struct bch_fs *c, struct bset *i, unsigned offset)
-{
-	struct nonce nonce = btree_nonce(i, offset);
-
-	if (!offset) {
-		struct btree_node *bn = container_of(i, struct btree_node, keys);
-		unsigned bytes = (void *) &bn->keys - (void *) &bn->flags;
-
-		bch2_encrypt(c, BSET_CSUM_TYPE(i), nonce, &bn->flags,
-			     bytes);
-
-		nonce = nonce_add(nonce, round_up(bytes, CHACHA_BLOCK_SIZE));
-	}
-
-	bch2_encrypt(c, BSET_CSUM_TYPE(i), nonce, i->_data,
-		     vstruct_end(i) - (void *) i->_data);
-}
-
 static void btree_err_msg(struct printbuf *out, struct bch_fs *c,
 			  struct btree *b, struct bset *i,
 			  unsigned offset, int write)

fs/bcachefs/btree_io.h

@@ -5,6 +5,7 @@
 #include "bkey_methods.h"
 #include "bset.h"
 #include "btree_locking.h"
+#include "checksum.h"
 #include "extents.h"
 #include "io_types.h"
 
@@ -82,6 +83,34 @@ static inline bool bch2_maybe_compact_whiteouts(struct bch_fs *c, struct btree *
 	return false;
 }
 
+static inline struct nonce btree_nonce(struct bset *i, unsigned offset)
+{
+	return (struct nonce) {{
+		[0] = cpu_to_le32(offset),
+		[1] = ((__le32 *) &i->seq)[0],
+		[2] = ((__le32 *) &i->seq)[1],
+		[3] = ((__le32 *) &i->journal_seq)[0]^BCH_NONCE_BTREE,
+	}};
+}
+
+static inline void bset_encrypt(struct bch_fs *c, struct bset *i, unsigned offset)
+{
+	struct nonce nonce = btree_nonce(i, offset);
+
+	if (!offset) {
+		struct btree_node *bn = container_of(i, struct btree_node, keys);
+		unsigned bytes = (void *) &bn->keys - (void *) &bn->flags;
+
+		bch2_encrypt(c, BSET_CSUM_TYPE(i), nonce, &bn->flags,
+			     bytes);
+
+		nonce = nonce_add(nonce, round_up(bytes, CHACHA_BLOCK_SIZE));
+	}
+
+	bch2_encrypt(c, BSET_CSUM_TYPE(i), nonce, i->_data,
+		     vstruct_end(i) - (void *) i->_data);
+}
+
 void bch2_btree_sort_into(struct bch_fs *, struct btree *, struct btree *);
 
 void bch2_btree_build_aux_trees(struct btree *);

fs/bcachefs/journal_seq_blacklist.c

@@ -36,15 +36,6 @@
  * that bset, until that btree node is rewritten.
  */
 
-static unsigned
-blacklist_nr_entries(struct bch_sb_field_journal_seq_blacklist *bl)
-{
-	return bl
-		? ((vstruct_end(&bl->field) - (void *) &bl->start[0]) /
-		   sizeof(struct journal_seq_blacklist_entry))
-		: 0;
-}
-
 static unsigned sb_blacklist_u64s(unsigned nr)
 {
 	struct bch_sb_field_journal_seq_blacklist *bl;

fs/bcachefs/journal_seq_blacklist.h

@@ -2,6 +2,15 @@
 #ifndef _BCACHEFS_JOURNAL_SEQ_BLACKLIST_H
 #define _BCACHEFS_JOURNAL_SEQ_BLACKLIST_H
 
+static inline unsigned
+blacklist_nr_entries(struct bch_sb_field_journal_seq_blacklist *bl)
+{
+	return bl
+		? ((vstruct_end(&bl->field) - (void *) &bl->start[0]) /
+		   sizeof(struct journal_seq_blacklist_entry))
+		: 0;
+}
+
 bool bch2_journal_seq_is_blacklisted(struct bch_fs *, u64, bool);
 int bch2_journal_seq_blacklist_add(struct bch_fs *c, u64, u64);
 int bch2_blacklist_table_initialize(struct bch_fs *);

fs/bcachefs/recovery.c

@@ -1039,6 +1039,11 @@ int bch2_fs_recovery(struct bch_fs *c)
 		}
 
 		journal_seq += 4;
+
+		/*
+		 * The superblock needs to be written before we do any btree
+		 * node writes: it will be in the read_write() path
+		 */
 	}
 
 	ret = bch2_blacklist_table_initialize(c);

fs/bcachefs/super.c

@@ -352,8 +352,8 @@ bool bch2_fs_emergency_read_only(struct bch_fs *c)
 {
 	bool ret = !test_and_set_bit(BCH_FS_EMERGENCY_RO, &c->flags);
 
-	bch2_fs_read_only_async(c);
 	bch2_journal_halt(&c->journal);
+	bch2_fs_read_only_async(c);
 
 	wake_up(&bch_read_only_wait);
 	return ret;
@@ -410,6 +410,13 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 	if (ret)
 		goto err;
 
+	/*
+	 * We need to write out a journal entry before we start doing btree
+	 * updates, to ensure that on unclean shutdown new journal blacklist
+	 * entries are created:
+	 */
+	bch2_journal_meta(&c->journal);
+
 	clear_bit(BCH_FS_ALLOC_CLEAN, &c->flags);
 
 	for_each_rw_member(ca, c, i)