Messages in this thread Patch in this message | | | Date | Thu, 13 Sep 2012 09:12:25 +1000 | Subject | Re: [Drbd-dev] FLUSH/FUA documentation & code discrepancy | From | Joseph Glanville <> |
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On 13 September 2012 04:58, Tejun Heo <tj@kernel.org> wrote: > Hello, > > On Tue, Sep 11, 2012 at 10:25:01AM +0200, Lars Ellenberg wrote: >> Or do we have a better place to document write ordering requirements? >> >> "To enforce write-after-write dependencies, you *have* to drain the >> queue (do we have a generic interface available for that?), >> or at least wait for the completion of all the requests you >> (potentially) depend upon, before even submitting the dependent request. >> >> Additionally, to avoid integrity issues due to volatile caches, >> you need to use FLUSH/FUA as appropriate." > > I think it would be best to note the lack of any ordering guarantee in > the comment of bio_submit()? Any one interested in submitting a > patch? > > Thanks. > > -- > tejun > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
Something along the lines of this?
diff --git a/block/blk-core.c b/block/blk-core.c index 4b4dbdf..68b5671 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1809,6 +1809,9 @@ EXPORT_SYMBOL(generic_make_request); * uses that function to do most of the work. Both are fairly rough * interfaces; @bio must be presetup and ready for I/O. * + * Ordering of requests is not guaranteed, callers should drain the queue + * and issue a flush before submission of any dependent bios. + * */ void submit_bio(int rw, struct bio *bio) { -- CTO | Orion Virtualisation Solutions | www.orionvm.com.au Phone: 1300 56 99 52 | Mobile: 0428 754 846
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