Bug 238312

Summary: [FUSEFS] writeback mode actually writes through
Product: Base System Reporter: Alan Somers <asomers>
Component: kernAssignee: Alan Somers <asomers>
Status: Closed FIXED    
Severity: Affects Many People CC: emaste
Priority: ---    
Version: CURRENT   
Hardware: Any   
OS: Any   

Description Alan Somers freebsd_committer freebsd_triage 2019-06-03 17:22:38 UTC 
fusefs has three sysctl-selectable cache modes: uncached, writethrough, and writeback.  Writeback mode is supposed to be the highest performance.  It's supposed to cache dirty data in the kernel and flush it occasionally, like UFS does.  However, it's never actually worked that way.  Instead, it writes through immediately.  Fixing this would probably be as simple as replacing the bwrite calls in fuse_write_biobackend with bdwrite.  But doing it correctly will require a little bit more work.
Comment 1 Alan Somers freebsd_committer freebsd_triage 2019-06-17 23:30:03 UTC 
Fixed by r349038.