bcachefs: bch_member.last_journal_bucket

On recovery from clean shutdown we don't typically read the journal, but
we still want to avoid overwriting existing entries in the journal for
list_journal debugging.

Thus, add some fields to the member info section so we can remember
where we left off.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs_format.h

@@ -589,6 +589,13 @@ struct bch_member {
 	__le64			errors_reset_time;
 	__le64			seq;
 	__le64			btree_allocated_bitmap;
+	/*
+	 * On recovery from a clean shutdown we don't normally read the journal,
+	 * but we still want to resume writing from where we left off so we
+	 * don't overwrite more than is necessary, for list journal debugging:
+	 */
+	__le32			last_journal_bucket;
+	__le32			last_journal_bucket_offset;
 };
 
 /*

fs/bcachefs/journal_io.c

@@ -17,6 +17,34 @@
 #include "sb-clean.h"
 #include "trace.h"
 
+void bch2_journal_pos_from_member_info_set(struct bch_fs *c)
+{
+	lockdep_assert_held(&c->sb_lock);
+
+	for_each_member_device(c, ca) {
+		struct bch_member *m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
+
+		m->last_journal_bucket = cpu_to_le32(ca->journal.cur_idx);
+		m->last_journal_bucket_offset = cpu_to_le32(ca->mi.bucket_size - ca->journal.sectors_free);
+	}
+}
+
+void bch2_journal_pos_from_member_info_resume(struct bch_fs *c)
+{
+	mutex_lock(&c->sb_lock);
+	for_each_member_device(c, ca) {
+		struct bch_member m = bch2_sb_member_get(c->disk_sb.sb, ca->dev_idx);
+
+		unsigned idx = le32_to_cpu(m.last_journal_bucket);
+		if (idx < ca->journal.nr)
+			ca->journal.cur_idx = idx;
+		unsigned offset = le32_to_cpu(m.last_journal_bucket_offset);
+		if (offset <= ca->mi.bucket_size)
+			ca->journal.sectors_free = ca->mi.bucket_size - offset;
+	}
+	mutex_unlock(&c->sb_lock);
+}
+
 void bch2_journal_ptrs_to_text(struct printbuf *out, struct bch_fs *c,
 			       struct journal_replay *j)
 {

fs/bcachefs/journal_io.h

@@ -4,6 +4,9 @@
 
 #include "darray.h"
 
+void bch2_journal_pos_from_member_info_set(struct bch_fs *);
+void bch2_journal_pos_from_member_info_resume(struct bch_fs *);
+
 struct journal_ptr {
 	bool		csum_good;
 	u8		dev;

fs/bcachefs/recovery.c

@@ -670,6 +670,8 @@ int bch2_fs_recovery(struct bch_fs *c)
 		goto err;
 	}
 
+	bch2_journal_pos_from_member_info_resume(c);
+
 	if (!c->sb.clean || c->opts.retain_recovery_info) {
 		struct genradix_iter iter;
 		struct journal_replay **i;

fs/bcachefs/sb-clean.c

@@ -390,6 +390,8 @@ void bch2_fs_mark_clean(struct bch_fs *c)
 		goto out;
 	}
 
+	bch2_journal_pos_from_member_info_set(c);
+
 	bch2_write_super(c);
 out:
 	mutex_unlock(&c->sb_lock);