Hello, this series addresses a performance issue caused by commit b685d3d65ac7 "block: treat REQ_FUA and REQ_PREFLUSH as synchronous". We know for certain this problem significanly regresses (over 10%, in some cases up to 100%) ext4 and btrfs for dbench4 and reaim benchmarks. Based on this I have fixed up also other places which suffer from the same problem however those changes are untested so maintainers please have a look whether the change makes sense to you and also whether I possibly didn't miss some cases where REQ_SYNC should be also added. Patches in this series are completely independent so if maintainers agree with the change, feel free to take it through your tree. The core of the problem is that above mentioned commit removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...} definitions. generic_make_request_checks() however strips REQ_FUA and REQ_PREFLUSH flags from a bio when the storage doesn't report volatile write cache and thus write effectively becomes asynchronous which can lead to performance regressions. A side note for ext4: The two patches for ext4 & jbd2 are on top of the change that got merged in the ext4 tree already. Honza -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel