On Tue, Mar 05, 2019 at 08:59:00PM -0600, Jayashree wrote: > In this file, we document the crash-recovery guarantees > provided by four Linux file systems - xfs, ext4, F2FS and btrfs. We also > present Dave Chinner's proposal of Strictly-Ordered Metadata Consistency > (SOMC), which is provided by xfs. It is not clear to us if other file systems > provide SOMC; we would be happy to modify the document if file-system > developers claim that their system provides (or aims to provide) SOMC. I haven't had time to read this yet, but I will point out that fstests assumes that filesystems that run "_require_metadata_journaling" tests present SOMC semantics to users. i.e. we are not testing POSIX semantics in fstests, we are testing for SOMC crash-recovery semantics because POSIX does not define a useful set of semantics. That was the whole point of genericising that test infrastructure - to make sure all the linux journalling filesystems behave the same way in the same circumstances... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
