Add support for O_ATOMIC
O_ATOMIC makes writes atomic, meaning that they are fully stable
on media (in the event of a power cut) when acknowledged by the
device and OS.
This only truly works on Linux with the pending patches to
add O_ATOMIC.
Updated by Jens to:
- Add man page and HOWTO description of the option
- Make O_ATOMIC imply O_DIRECT, so that it actually works if you
don't set O_DIRECT manually.
- Add the option to the conversion list so it works for
client/server.
- Error handling so that if atomic=1 is set and the OS does not
support it, error out instead of just pretending it works.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/HOWTO b/HOWTO
index eb2ed25..250bc58 100644
--- a/HOWTO
+++ b/HOWTO
@@ -695,6 +695,11 @@
O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
On Windows the synchronous ioengines don't support direct io.
+atomic=bool If value is true, attempt to use atomic direct IO. Atomic
+ writes are guaranteed to be stable once acknowledged by
+ the operating system. Only Linux supports O_ATOMIC right
+ now.
+
buffered=bool If value is true, use buffered io. This is the opposite
of the 'direct' option. Defaults to true.