bcachefs: journal_seq_blacklist_add() now handles entries being added out of order

bch2_journal_seq_blacklist_add() was bugged when the new entry
overlapped with multiple existing entries, and it also assumed new
entries are being added in increasing order.

This is true on any sane filesystem, but when trying to recover from
very badly mangled filesystems we might end up with the journal sequence
number rewinding vs. what the blacklist list knows about - easiest to
just handle that here.

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

1 files changed, 21 insertions, 45 deletions

diff --git a/fs/bcachefs/journal_seq_blacklist.c b/fs/bcachefs/journal_seq_blacklist.c
index 0200e299cfbb..5acc1276675c 100644
--- a/fs/bcachefs/journal_seq_blacklist.c
+++ b/fs/bcachefs/journal_seq_blacklist.c
@@ -43,61 +43,36 @@ static unsigned sb_blacklist_u64s(unsigned nr)
 	return (sizeof(*bl) + sizeof(bl->start[0]) * nr) / sizeof(u64);
 }
 
-static struct bch_sb_field_journal_seq_blacklist *
-blacklist_entry_try_merge(struct bch_fs *c,
-			  struct bch_sb_field_journal_seq_blacklist *bl,
-			  unsigned i)
-{
-	unsigned nr = blacklist_nr_entries(bl);
-
-	if (le64_to_cpu(bl->start[i].end) >=
-	    le64_to_cpu(bl->start[i + 1].start)) {
-		bl->start[i].end = bl->start[i + 1].end;
-		--nr;
-		memmove(&bl->start[i],
-			&bl->start[i + 1],
-			sizeof(bl->start[0]) * (nr - i));
-
-		bl = bch2_sb_field_resize(&c->disk_sb, journal_seq_blacklist,
-					  sb_blacklist_u64s(nr));
-		BUG_ON(!bl);
-	}
-
-	return bl;
-}
-
-static bool bl_entry_contig_or_overlaps(struct journal_seq_blacklist_entry *e,
-					u64 start, u64 end)
-{
-	return !(end < le64_to_cpu(e->start) || le64_to_cpu(e->end) < start);
-}
-
 int bch2_journal_seq_blacklist_add(struct bch_fs *c, u64 start, u64 end)
 {
 	struct bch_sb_field_journal_seq_blacklist *bl;
-	unsigned i, nr;
+	unsigned i = 0, nr;
 	int ret = 0;
 
 	mutex_lock(&c->sb_lock);
 	bl = bch2_sb_field_get(c->disk_sb.sb, journal_seq_blacklist);
 	nr = blacklist_nr_entries(bl);
 
-	for (i = 0; i < nr; i++) {
+	while (i < nr) {
 		struct journal_seq_blacklist_entry *e =
 			bl->start + i;
 
-		if (bl_entry_contig_or_overlaps(e, start, end)) {
-			e->start = cpu_to_le64(min(start, le64_to_cpu(e->start)));
-			e->end	= cpu_to_le64(max(end, le64_to_cpu(e->end)));
-
-			if (i + 1 < nr)
-				bl = blacklist_entry_try_merge(c,
-							bl, i);
-			if (i)
-				bl = blacklist_entry_try_merge(c,
-							bl, i - 1);
-			goto out_write_sb;
+		if (end < le64_to_cpu(e->start))
+			break;
+
+		if (start > le64_to_cpu(e->end)) {
+			i++;
+			continue;
 		}
+
+		/*
+		 * Entry is contiguous or overlapping with new entry: merge it
+		 * with new entry, and delete:
+		 */
+
+		start	= min(start,	le64_to_cpu(e->start));
+		end	= max(end,	le64_to_cpu(e->end));
+		array_remove_item(bl->start, nr, i);
 	}
 
 	bl = bch2_sb_field_resize(&c->disk_sb, journal_seq_blacklist,
@@ -107,9 +82,10 @@ int bch2_journal_seq_blacklist_add(struct bch_fs *c, u64 start, u64 end)
 		goto out;
 	}
 
-	bl->start[nr].start	= cpu_to_le64(start);
-	bl->start[nr].end	= cpu_to_le64(end);
-out_write_sb:
+	array_insert_item(bl->start, nr, i, ((struct journal_seq_blacklist_entry) {
+		.start	= cpu_to_le64(start),
+		.end	= cpu_to_le64(end),
+	}));
 	c->disk_sb.sb->features[0] |= cpu_to_le64(1ULL << BCH_FEATURE_journal_seq_blacklist_v3);
 
 	ret = bch2_write_super(c);