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block: set REQ_SYNC if we clear REQ_FUA|REQ_PREFLUSH 

If we insert a flush request, we clear REQ_PREFLUSH and/or REQ_FUA,
depending on flush settings. Since op_is_sync() factors those flags
in for deciding whether this request is sync or not, we should
set REQ_SYNC to avoid screwing up this accounting.

This should be less fragile.

Reported-by: Logan Gunthorpe <logang@deltatee.com>
Fixes: b685d3d65a ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous")
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jens Axboe 2016-11-08 19:39:28 -07:00
parent b57d74aff9
commit ae5b2ec8ad
1 changed files with 7 additions and 0 deletions
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7
block/blk-flush.c
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@ -395,6 +395,13 @@ void blk_insert_flush(struct request *rq)
if (!(fflags & (1UL << QUEUE_FLAG_FUA)))
rq->cmd_flags &= ~REQ_FUA;
/*
* REQ_PREFLUSH|REQ_FUA implies REQ_SYNC, so if we clear any
* of those flags, we have to set REQ_SYNC to avoid skewing
* the request accounting.
*/
rq->cmd_flags |= REQ_SYNC;
/*
* An empty flush handed down from a stacking driver may
* translate into nothing if the underlying device does not