bcachefs: Check for too-large encoded extents

We don't yet repair (split) them, just check.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/extents.c

@@ -1207,6 +1207,14 @@ int bch2_bkey_ptrs_invalid(const struct bch_fs *c, struct bkey_s_c k,
 				return -BCH_ERR_invalid_bkey;
 			}
 			crc_since_last_ptr = true;
+
+			if (crc_is_encoded(crc) &&
+			    (crc.uncompressed_size > c->opts.encoded_extent_max >> 9) &&
+			    (flags & (BKEY_INVALID_WRITE|BKEY_INVALID_COMMIT))) {
+				prt_printf(err, "too large encoded extent");
+				return -BCH_ERR_invalid_bkey;
+			}
+
 			break;
 		case BCH_EXTENT_ENTRY_stripe_ptr:
 			if (have_ec) {

fs/bcachefs/extents.h

@@ -190,6 +190,11 @@ static inline bool crc_is_compressed(struct bch_extent_crc_unpacked crc)
 		crc.compression_type != BCH_COMPRESSION_TYPE_incompressible);
 }
 
+static inline bool crc_is_encoded(struct bch_extent_crc_unpacked crc)
+{
+	return crc.csum_type != BCH_CSUM_none || crc_is_compressed(crc);
+}
+
 /* bkey_ptrs: generically over any key type that has ptrs */
 
 struct bkey_ptrs_c {

fs/bcachefs/fsck.c

@@ -1299,6 +1299,28 @@ static int check_overlapping_extents(struct btree_trans *trans,
 	return ret;
 }
 
+static int check_extent_overbig(struct btree_trans *trans, struct btree_iter *iter,
+				struct bkey_s_c k)
+{
+	struct bch_fs *c = trans->c;
+	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+	struct bch_extent_crc_unpacked crc;
+	const union bch_extent_entry *i;
+	unsigned encoded_extent_max_sectors = c->opts.encoded_extent_max >> 9;
+
+	bkey_for_each_crc(k.k, ptrs, crc, i)
+		if (crc_is_encoded(crc) &&
+		    crc.uncompressed_size > encoded_extent_max_sectors) {
+			struct printbuf buf = PRINTBUF;
+
+			bch2_bkey_val_to_text(&buf, c, k);
+			bch_err(c, "overbig encoded extent, please report this:\n  %s", buf.buf);
+			printbuf_exit(&buf);
+		}
+
+	return 0;
+}
+
 static int check_extent(struct btree_trans *trans, struct btree_iter *iter,
 			struct bkey_s_c k,
 			struct inode_walker *inode,
@@ -1434,7 +1456,8 @@ int bch2_check_extents(struct bch_fs *c)
 			&res, NULL,
 			BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL, ({
 		bch2_disk_reservation_put(c, &res);
-		check_extent(trans, &iter, k, &w, &s, &extent_ends);
+		check_extent(trans, &iter, k, &w, &s, &extent_ends) ?:
+		check_extent_overbig(trans, &iter, k);
 	})) ?:
 	check_i_sectors(trans, &w);
 
@@ -1448,6 +1471,30 @@ int bch2_check_extents(struct bch_fs *c)
 	return ret;
 }
 
+int bch2_check_indirect_extents(struct bch_fs *c)
+{
+	struct btree_trans *trans = bch2_trans_get(c);
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	struct disk_reservation res = { 0 };
+	int ret = 0;
+
+	ret = for_each_btree_key_commit(trans, iter, BTREE_ID_reflink,
+			POS_MIN,
+			BTREE_ITER_PREFETCH, k,
+			&res, NULL,
+			BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL, ({
+		bch2_disk_reservation_put(c, &res);
+		check_extent_overbig(trans, &iter, k);
+	}));
+
+	bch2_disk_reservation_put(c, &res);
+	bch2_trans_put(trans);
+
+	bch_err_fn(c, ret);
+	return ret;
+}
+
 static int check_subdir_count(struct btree_trans *trans, struct inode_walker *w)
 {
 	struct bch_fs *c = trans->c;

fs/bcachefs/fsck.h

@@ -4,6 +4,7 @@
 
 int bch2_check_inodes(struct bch_fs *);
 int bch2_check_extents(struct bch_fs *);
+int bch2_check_indirect_extents(struct bch_fs *);
 int bch2_check_dirents(struct bch_fs *);
 int bch2_check_xattrs(struct bch_fs *);
 int bch2_check_root(struct bch_fs *);

fs/bcachefs/io_write.c

@@ -1092,9 +1092,7 @@ static bool bch2_extent_is_writeable(struct bch_write_op *op,
 
 	e = bkey_s_c_to_extent(k);
 	extent_for_each_ptr_decode(e, p, entry) {
-		if (p.crc.csum_type ||
-		    crc_is_compressed(p.crc) ||
-		    p.has_ec)
+		if (crc_is_encoded(p.crc) || p.has_ec)
 			return false;
 
 		replicas += bch2_extent_ptr_durability(c, &p);

fs/bcachefs/recovery_types.h

@@ -34,6 +34,7 @@
 	x(resume_logged_ops,		PASS_ALWAYS)						\
 	x(check_inodes,			PASS_FSCK)						\
 	x(check_extents,		PASS_FSCK)						\
+	x(check_indirect_extents,	PASS_FSCK)						\
 	x(check_dirents,		PASS_FSCK)						\
 	x(check_xattrs,			PASS_FSCK)						\
 	x(check_root,			PASS_FSCK)						\