Hello, On Fri, Mar 14, 2014 at 11:07:04PM +0900, Roman Peniaev wrote: > Seems the following message should be better: > When data inegrity operation (sync, fsync, fdatasync calls) happens > writeback control is set to WB_SYNC_ALL. > In that case all write requests are marked with WRITE_SYNC, but on > mpage writeback path > WRITE_SYNC is missed. This patch fixes this. > > Is it ok, what do you think?
I think the description should make it clear that WRITE_SYNC is about latency, not about integrity and we probably should add comments explaining why we're using WRITE_SYNC for WB_SYNC_ALL (because there probably is someone waiting). > Also, could you please help me do understand how can I guarantee > integrity in case of block device with big volatile > cache and filesystem, which does not support REQ_FLUSH/FUA? If a device has a volatile cache but doesn't support flush, it can't guarantee integrity. There's no way for its user to determine or force whether certain data is on non-volatile media. It's an inherently broken device. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
