On Fri, Nov 13, 2015 at 4:06 PM, Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> wrote: > Currently the PMEM driver doesn't accept REQ_FLUSH or REQ_FUA bios. These > are sent down via blkdev_issue_flush() in response to a fsync() or msync() > and are used by filesystems to order their metadata, among other things. > > When we get an msync() or fsync() it is the responsibility of the DAX code > to flush all dirty pages to media. The PMEM driver then just has issue a > wmb_pmem() in response to the REQ_FLUSH to ensure that before we return all > the flushed data has been durably stored on the media. > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> Hmm, I'm not seeing why we need this patch. If the actual flushing of the cache is done by the core why does the driver need support REQ_FLUSH? Especially since it's just a couple instructions. REQ_FUA only makes sense if individual writes can bypass the "drive" cache, but no I/O submitted to the driver proper is ever cached we always flush it through to media. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>