Function probe 

pub async fn probe(
    dir: &Path,
    pragmas: Option<SqlitePragmas>,
) -> Result<StorageProbe>

Runs the blocking half on a dedicated thread under PROBE_TIMEOUT, and returns an error if it expires. canonicalize is inside that half deliberately: stat on a hung hard mount blocks uninterruptibly, so the classification can hang before the fsync probe is even reached.

Logs the filesystem classification as soon as it is known, so a mount whose fdatasync hangs still says which filesystem it was.