blkdev_issue_flush appears to be a NOOP for request-based srivers, because
it returns -ENXIO if no make_request_function is present. AIUI only bio
based drivers have a make_request_function. The preceding comment suggests
this is an attempt to avoid making a request to bio based drivers before
their queue is set up. This should not exclude request based drivers from
getting any flushes. Instead therefore check for EITHER
make_request_function OR request_function and queue flags. The check for
queue flags may be unnecessary as the block layer may simply not send the
flush on.
--
Alex Bligh
Signed-Off-By: Alex Bligh <alex@xxxxxxxxxxx>
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 6c9b5e1..3a6d4bd 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -405,13 +405,14 @@ int blkdev_issue_flush(struct block_device *bdev,
gfp_t gfp_mask,
/*
* some block devices may not have their queue correctly set up here
* (e.g. loop device without a backing file) and so issuing a flush
* here will panic. Ensure there is a request function before
issuing
* the flush.
*/
- if (!q->make_request_fn)
+ if (!q->make_request_fn &&
+ !(q->request_fn && (q->flush_flags & REQ_FLUSH)))
return -ENXIO;
bio = bio_alloc(gfp_mask, 0);
bio->bi_end_io = bio_end_flush;
bio->bi_bdev = bdev;
bio->bi_private = &wait;
--
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