test(filemeta): cover crc heal classification (#5841)

* fix(filemeta): classify xl.meta CRC mismatch as FileCorrupt so heal repairs it

A failed CRC means the metadata bytes on disk are not the bytes that were
written — bitrot. Raising it as Error::other() surfaces a generic Io error,
which should_heal_object_on_disk does not recognise as heal-worthy: the drive
is skipped, disks_to_heal_count stays 0, heal_object returns ok, and the
corrupted xl.meta is never rewritten — while the scanner re-submits the same
no-op heal every deep-scan cycle. An explicit admin deep heal fails the same
way, so no heal path repairs metadata bitrot, and every one of them reports
success.

check_xl2_v1 already classifies a short or wrong-magic header as FileCorrupt
for exactly this reason (#5716); this completes the pattern for the two CRC
sites. The existing From<rustfs_filemeta::Error> for DiskError conversion maps
the variant to DiskError::FileCorrupt, which the heal path already handles.
The previously silent is_indexed_meta site now logs the mismatch (structured
event shape) like unmarshal_msg does.

Regression test: corrupt one byte of a marshalled FileMeta and assert
unmarshal_msg reports FileCorrupt; fails on the previous code, which returned
Io(Other).

Verified end-to-end on a 3-node / 12-drive EC:4 cluster: xl.meta corrupted on
2 of 12 drives via dd, admin deep heal — before this change the heal returns
ok with the corruption intact and the scanner loops forever; with it, both
copies are rewritten (decode-identical to the healthy quorum), the object
reads back byte-correct, and a follow-up heal reports all twelve drives
clean.

* test(filemeta): cover crc heal classification

Add regression coverage for the indexed xl.meta CRC path and the metadata-heal decision that consumes FileCorrupt.

Co-Authored-By: heihutu <heihutu@gmail.com>

---------

Co-authored-by: terem42 <9478806+terem42@users.noreply.github.com>
Co-authored-by: heihutu <heihutu@gmail.com>
Co-authored-by: zhi22915 <qiuzgang@gmail.com>

crates/ecstore/src/set_disk/mod.rs

@@ -7391,6 +7391,12 @@ mod tests {
         let (should_heal, _, _) = should_heal_object_on_disk(&err, &[], &meta, &latest_meta);
         assert!(should_heal);
 
+        let err = Some(DiskError::FileCorrupt);
+        let (should_heal, is_meta, reason) = should_heal_object_on_disk(&err, &[], &meta, &latest_meta);
+        assert!(should_heal);
+        assert!(is_meta);
+        assert_eq!(reason, Some(DiskError::FileCorrupt));
+
         // Test with no error and no part errors
         let (should_heal, _, _) = should_heal_object_on_disk(&None, &[CHECK_PART_SUCCESS], &meta, &latest_meta);
         assert!(!should_heal);

crates/filemeta/src/filemeta.rs

@@ -1481,6 +1481,17 @@ mod test {
         assert_eq!(err, Error::FileCorrupt, "CRC mismatch must classify as FileCorrupt, got: {err}");
     }
 
+    #[test]
+    fn test_is_indexed_meta_reports_file_corrupt_on_crc_mismatch() {
+        let fm = FileMeta::default();
+        let mut buf = fm.marshal_msg().expect("serialize default FileMeta");
+        let idx = 8 + 5;
+        buf[idx] ^= 0xff;
+
+        let err = FileMeta::is_indexed_meta(&buf).expect_err("corrupted indexed metadata must fail");
+        assert_eq!(err, Error::FileCorrupt, "indexed CRC mismatch must classify as FileCorrupt, got: {err}");
+    }
+
     #[test]
     fn test_unmarshal_rejects_absurd_version_count() {
         let mut meta = Vec::new();