On 06/08/2013 02:11 AM, Sergei Trofimovich wrote: > On Fri, 07 Jun 2013 23:47:33 -0400 > Richard Yao <r...@gentoo.org> wrote: > >> When you use dm-crypt, block IO requests to a dm-* device will invoke >> dm_request_fn() -> map_request() -> crypt_map(). If a BIO is a write >> barrier, crypt_map() will return DM_MAPIO_REMAPPED to map_request(), >> which will immediately queue it to the device. >> >> If a few dozen IOs are queued in rapid succession with multiple write >> barriers, all write barriers will be executed before any actual write >> BIOs occur because the write IOs will be processed asynchronously in a >> work queue. Since the barriers will be long gone by the time the write >> IOs are queued, they can be queued in any order. >> >> Am I misunderstanding this or is dm-crypt ignoring proper write barrier >> semantics? >> > http://www.saout.de/pipermail/dm-crypt/2012-April/002441.html > http://lwn.net/Articles/400541/ >
It might be worth stating that I thought flush was a synonym for barrier. It still looks like there is an issue, despite my incorrect terminology.
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