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xen/blkfront: map REQ_FLUSH into a full barrier
Implement a flush as a full barrier, since we have nothing weaker. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Christoph Hellwig <hch@lst.de>
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c8ddb2713c
commit
c64e38ea17
1 changed files with 5 additions and 14 deletions
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@ -245,14 +245,11 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
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}
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/*
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* blkif_queue_request
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* Generate a Xen blkfront IO request from a blk layer request. Reads
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* and writes are handled as expected. Since we lack a loose flush
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* request, we map flushes into a full ordered barrier.
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*
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* request block io
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*
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* id: for guest use only.
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* operation: BLKIF_OP_{READ,WRITE,PROBE}
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* buffer: buffer to read/write into. this should be a
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* virtual address in the guest os.
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* @req: a request struct
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*/
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static int blkif_queue_request(struct request *req)
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{
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@ -289,7 +286,7 @@ static int blkif_queue_request(struct request *req)
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ring_req->operation = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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if (req->cmd_flags & REQ_HARDBARRIER)
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if (req->cmd_flags & REQ_FLUSH)
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ring_req->operation = BLKIF_OP_WRITE_BARRIER;
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ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
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@ -1069,14 +1066,8 @@ static void blkfront_connect(struct blkfront_info *info)
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*/
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info->feature_flush = 0;
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/*
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* The driver doesn't properly handled empty flushes, so
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* lets disable barrier support for now.
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*/
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#if 0
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if (!err && barrier)
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info->feature_flush = REQ_FLUSH;
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#endif
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err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
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if (err) {
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