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authorJeff Moyer <jmoyer@redhat.com>2011-08-09 20:32:09 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-08-09 20:32:09 +0200
commitfa1bf42ff9296ac4cf211b0a1b450a6071d26a95 (patch)
tree0c7f43ca005c70022e64abb8b8d0b0d549b73959 /block
parent4931402a9dd00b2997e95bfbb89409b2a6dbb383 (diff)
downloadlinux-stericsson-fa1bf42ff9296ac4cf211b0a1b450a6071d26a95.tar.gz
allow blk_flush_policy to return REQ_FSEQ_DATA independent of *FLUSH
blk_insert_flush has the following check: /* * If there's data but flush is not necessary, the request can be * processed directly without going through flush machinery. Queue * for normal execution. */ if ((policy & REQ_FSEQ_DATA) && !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) { list_add_tail(&rq->queuelist, &q->queue_head); return; } However, blk_flush_policy will not return with policy set to only REQ_FSEQ_DATA: static unsigned int blk_flush_policy(unsigned int fflags, struct request *rq) { unsigned int policy = 0; if (fflags & REQ_FLUSH) { if (rq->cmd_flags & REQ_FLUSH) policy |= REQ_FSEQ_PREFLUSH; if (blk_rq_sectors(rq)) policy |= REQ_FSEQ_DATA; if (!(fflags & REQ_FUA) && (rq->cmd_flags & REQ_FUA)) policy |= REQ_FSEQ_POSTFLUSH; } return policy; } Notice that REQ_FSEQ_DATA is only set if REQ_FLUSH is set. Fix this mismatch by moving the setting of REQ_FSEQ_DATA outside of the REQ_FLUSH check. Tejun notes: Hmmm... yes, this can become a correctness issue if (and only if) blk_queue_flush() is called to change q->flush_flags while requests are in-flight; otherwise, requests wouldn't reach the function at all. Also, I think it would be a generally good idea to always set FSEQ_DATA if the request has data. Cheers, Jeff Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-flush.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/block/blk-flush.c b/block/blk-flush.c
index bb21e4c36f70..2d162bd840d3 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -95,11 +95,12 @@ static unsigned int blk_flush_policy(unsigned int fflags, struct request *rq)
{
unsigned int policy = 0;
+ if (blk_rq_sectors(rq))
+ policy |= REQ_FSEQ_DATA;
+
if (fflags & REQ_FLUSH) {
if (rq->cmd_flags & REQ_FLUSH)
policy |= REQ_FSEQ_PREFLUSH;
- if (blk_rq_sectors(rq))
- policy |= REQ_FSEQ_DATA;
if (!(fflags & REQ_FUA) && (rq->cmd_flags & REQ_FUA))
policy |= REQ_FSEQ_POSTFLUSH;
}