? EXT2_GOOD_OLD_INODE_SIZE \
: grub_le_to_cpu16 (data->sblock.inode_size))
-#define EXT3_FEATURE_COMPAT_HAS_JOURNAL 0x0004
+/* Superblock filesystem feature flags (RW compatible)
+ * A filesystem with any of these enabled can be read and written by a driver
+ * that does not understand them without causing metadata/data corruption */
+#define EXT2_FEATURE_COMPAT_DIR_PREALLOC 0x0001
+#define EXT2_FEATURE_COMPAT_IMAGIC_INODES 0x0002
+#define EXT3_FEATURE_COMPAT_HAS_JOURNAL 0x0004
+#define EXT2_FEATURE_COMPAT_EXT_ATTR 0x0008
+#define EXT2_FEATURE_COMPAT_RESIZE_INODE 0x0010
+#define EXT2_FEATURE_COMPAT_DIR_INDEX 0x0020
+/* Superblock filesystem feature flags (RO compatible)
+ * A filesystem with any of these enabled can be safely read by a driver that
+ * does not understand them, but should not be written to, usually because
+ * additional metadata is required */
+#define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
+#define EXT2_FEATURE_RO_COMPAT_LARGE_FILE 0x0002
+#define EXT2_FEATURE_RO_COMPAT_BTREE_DIR 0x0004
+#define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010
+#define EXT4_FEATURE_RO_COMPAT_DIR_NLINK 0x0020
+#define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE 0x0040
+/* Superblock filesystem feature flags (back-incompatible)
+ * A filesystem with any of these enabled should not be attempted to be read
+ * by a driver that does not understand them, since they usually indicate
+ * metadata format changes that might confuse the reader. */
+#define EXT2_FEATURE_INCOMPAT_COMPRESSION 0x0001
+#define EXT2_FEATURE_INCOMPAT_FILETYPE 0x0002
+#define EXT3_FEATURE_INCOMPAT_RECOVER 0x0004 /* Needs recovery */
+#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008 /* Volume is journal device */
+#define EXT2_FEATURE_INCOMPAT_META_BG 0x0010
+#define EXT4_FEATURE_INCOMPAT_EXTENTS 0x0040 /* Extents used */
+#define EXT4_FEATURE_INCOMPAT_64BIT 0x0080
+#define EXT4_FEATURE_INCOMPAT_FLEX_BG 0x0200
+
+/* The set of back-incompatible features this driver DOES support. Add (OR)
+ * flags here as the related features are implemented into the driver */
+#define EXT2_DRIVER_SUPPORTED_INCOMPAT ( EXT2_FEATURE_INCOMPAT_FILETYPE \
+ | EXT4_FEATURE_INCOMPAT_EXTENTS )
+/* List of rationales for the ignored "incompatible" features:
+ * needs_recovery: Not really back-incompatible - was added as such to forbid
+ * ext2 drivers from mounting an ext3 volume with a dirty
+ * journal because they will ignore the journal, but the next
+ * ext3 driver to mount the volume will find the journal and
+ * replay it, potentially corrupting the metadata written by
+ * the ext2 drivers
+ */
+#define EXT2_DRIVER_IGNORED_INCOMPAT ( EXT3_FEATURE_INCOMPAT_RECOVER )
+
#define EXT3_JOURNAL_MAGIC_NUMBER 0xc03b3998U
/* Make sure this is an ext2 filesystem. */
if (grub_le_to_cpu16 (data->sblock.magic) != EXT2_MAGIC)
- goto fail;
+ {
+ grub_error (GRUB_ERR_BAD_FS, "not an ext2 filesystem");
+ goto fail;
+ }
+
+ /* Check the FS doesn't have feature bits enabled that we don't support. */
+ if (grub_le_to_cpu32 (data->sblock.feature_incompat)
+ & ~(EXT2_DRIVER_SUPPORTED_INCOMPAT | EXT2_DRIVER_IGNORED_INCOMPAT))
+ {
+ grub_error (GRUB_ERR_BAD_FS, "filesystem has unsupported incompatible features");
+ goto fail;
+ }
+
data->disk = disk;
return data;
fail:
- grub_error (GRUB_ERR_BAD_FS, "not an ext2 filesystem");
grub_free (data);
return 0;
}