Allow loading filesystems with the recovery bit

This is the final step of enabling journal support. Since the test
filesystem can now be loaded, this commit also adds some tests.

Author: nicholasbishop

CHANGELOG.md

@@ -28,6 +28,7 @@
 * Added `Ext4::uuid` to get the filesystem UUID.
 * Made the `Corrupt` type opaque. It is no longer possible to `match` on
   specific types of corruption.
+* Added support for reading filesystems that weren't cleanly unmounted.
 
 ## 0.7.0
 

src/journal.rs

@@ -59,3 +59,24 @@ impl Journal {
         *self.block_map.get(&block_index).unwrap_or(&block_index)
     }
 }
+
+#[cfg(all(test, feature = "std"))]
+mod tests {
+    use crate::test_util::load_compressed_filesystem;
+    use alloc::rc::Rc;
+
+    #[test]
+    fn test_journal() {
+        let mut fs =
+            load_compressed_filesystem("test_disk_4k_block_journal.bin.zst");
+
+        let test_dir = "/dir500";
+
+        // With the journal in place, this directory exists.
+        assert!(fs.exists(test_dir).unwrap());
+
+        // Clear the journal, and verify that the directory no longer exists.
+        Rc::get_mut(&mut fs.0).unwrap().journal.block_map.clear();
+        assert!(!fs.exists(test_dir).unwrap());
+    }
+}

src/journal/superblock.rs

@@ -197,6 +197,28 @@ fn check_incompat_features(
 #[cfg(all(test, feature = "std"))]
 mod tests {
     use super::*;
+    use crate::test_util::load_compressed_filesystem;
+
+    #[test]
+    fn test_load_journal_superblock() {
+        let fs =
+            load_compressed_filesystem("test_disk_4k_block_journal.bin.zst");
+        let journal_inode =
+            Inode::read(&fs, fs.0.superblock.journal_inode.unwrap()).unwrap();
+        let superblock = JournalSuperblock::load(&fs, &journal_inode).unwrap();
+        assert_eq!(
+            superblock,
+            JournalSuperblock {
+                block_size: 4096,
+                sequence: 3,
+                start_block: 289,
+                uuid: Uuid([
+                    0x6c, 0x48, 0x4f, 0x1b, 0x7f, 0x71, 0x47, 0x4c, 0xa1, 0xf9,
+                    0x3b, 0x50, 0x0c, 0xc1, 0xe2, 0x74
+                ]),
+            }
+        );
+    }
 
     fn write_u32be(bytes: &mut [u8], offset: usize, value: u32) {
         bytes[offset..offset + 4].copy_from_slice(&value.to_be_bytes());

src/superblock.rs

@@ -201,7 +201,6 @@ fn check_incompat_features(
     // relax some of these in the future.
     let required_features = IncompatibleFeatures::FILE_TYPE_IN_DIR_ENTRY;
     let disallowed_features = IncompatibleFeatures::COMPRESSION
-        | IncompatibleFeatures::RECOVERY
         | IncompatibleFeatures::SEPARATE_JOURNAL_DEVICE
         | IncompatibleFeatures::META_BLOCK_GROUPS
         | IncompatibleFeatures::MULTIPLE_MOUNT_PROTECTION