Force sync writes to meta.json in case of host crash (thanos-io#8282)

* Force sync writes to meta.json in case of host crash

Signed-off-by: Anna Tran <trananna@amazon.com>

* Update CHANGELOG for fsync meta.json

Signed-off-by: Anna Tran <trananna@amazon.com>

---------

Signed-off-by: Anna Tran <trananna@amazon.com>

Author: anna-tran

CHANGELOG.md

@@ -12,6 +12,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#8190](https://github.com/thanos-io/thanos/pull/8190) Fix markdown formatting in CHANGELOG.
 - [#8202](https://github.com/thanos-io/thanos/pull/8202) Receive: Unhide `--tsdb.enable-native-histograms` flag
 - [#8225](https://github.com/thanos-io/thanos/pull/8225) tools: Extend bucket ls options.
+- [#8282](https://github.com/thanos-io/thanos/pull/8282) Force sync writes to meta.json in case of host crash
 
 ### Added
 

pkg/block/metadata/meta.go

@@ -209,6 +209,11 @@ func (m Meta) WriteToDir(logger log.Logger, dir string) error {
 		runutil.CloseWithLogOnErr(logger, f, "close meta")
 		return err
 	}
+
+	// Force the kernel to persist the file on disk to avoid data loss if the host crashes.
+	if err := f.Sync(); err != nil {
+		return err
+	}
 	if err := f.Close(); err != nil {
 		return err
 	}

pkg/shipper/shipper.go

@@ -467,6 +467,11 @@ func WriteMetaFile(logger log.Logger, path string, meta *Meta) error {
 		runutil.CloseWithLogOnErr(logger, f, "write meta file close")
 		return err
 	}
+
+	// Force the kernel to persist the file on disk to avoid data loss if the host crashes.
+	if err := f.Sync(); err != nil {
+		return err
+	}
 	if err := f.Close(); err != nil {
 		return err
 	}