bcachefs: Check for invalid bucket from bucket_gen(), gc_bucket()

Turn more asserts into proper recoverable error paths.

Reported-by: syzbot+246b47da27f8e7e7d6fb@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 22 insertions, 8 deletions

diff --git a/fs/bcachefs/io_read.c b/fs/bcachefs/io_read.c
index 862b79f86b91..c97fa7002b06 100644
--- a/fs/bcachefs/io_read.c
+++ b/fs/bcachefs/io_read.c
@@ -777,18 +777,32 @@ static noinline void read_from_stale_dirty_pointer(struct btree_trans *trans,
 			     PTR_BUCKET_POS(ca, &ptr),
 			     BTREE_ITER_cached);
 
-	prt_printf(&buf, "Attempting to read from stale dirty pointer:\n");
-	printbuf_indent_add(&buf, 2);
+	u8 *gen = bucket_gen(ca, iter.pos.offset);
+	if (gen) {
 
-	bch2_bkey_val_to_text(&buf, c, k);
-	prt_newline(&buf);
+		prt_printf(&buf, "Attempting to read from stale dirty pointer:\n");
+		printbuf_indent_add(&buf, 2);
 
-	prt_printf(&buf, "memory gen: %u", *bucket_gen(ca, iter.pos.offset));
-
-	ret = lockrestart_do(trans, bkey_err(k = bch2_btree_iter_peek_slot(&iter)));
-	if (!ret) {
+		bch2_bkey_val_to_text(&buf, c, k);
 		prt_newline(&buf);
+
+		prt_printf(&buf, "memory gen: %u", *gen);
+
+		ret = lockrestart_do(trans, bkey_err(k = bch2_btree_iter_peek_slot(&iter)));
+		if (!ret) {
+			prt_newline(&buf);
+			bch2_bkey_val_to_text(&buf, c, k);
+		}
+	} else {
+		prt_printf(&buf, "Attempting to read from invalid bucket %llu:%llu:\n",
+			   iter.pos.inode, iter.pos.offset);
+		printbuf_indent_add(&buf, 2);
+
+		prt_printf(&buf, "first bucket %u nbuckets %llu\n",
+			   ca->mi.first_bucket, ca->mi.nbuckets);
+
 		bch2_bkey_val_to_text(&buf, c, k);
+		prt_newline(&buf);
 	}
 
 	bch2_fs_inconsistent(c, "%s", buf.buf);