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authorChristoph Hellwig <hch@lst.de>2017-11-02 21:29:50 +0300
committerJens Axboe <axboe@kernel.dk>2017-11-03 10:31:48 -0600
commitf421e1d9ade4e1b88183e54425cf50e390d16a7f (patch)
tree3a60f286c4e7884dea8408b091ba90f60c47a954 /block
parent96222bcc732d0504363dc772637c50e53b4bd41e (diff)
block: provide a direct_make_request helper
This helper allows reinserting a bio into a new queue without much overhead, but requires all queue limits to be the same for the upper and lower queues, and it does not provide any recursion preventions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Javier González <javier@cnexlabs.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index bb4fce694a60..96aaa3a419a3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2244,6 +2244,40 @@ out:
EXPORT_SYMBOL(generic_make_request);
/**
+ * direct_make_request - hand a buffer directly to its device driver for I/O
+ * @bio: The bio describing the location in memory and on the device.
+ *
+ * This function behaves like generic_make_request(), but does not protect
+ * against recursion. Must only be used if the called driver is known
+ * to not call generic_make_request (or direct_make_request) again from
+ * its make_request function. (Calling direct_make_request again from
+ * a workqueue is perfectly fine as that doesn't recurse).
+ */
+blk_qc_t direct_make_request(struct bio *bio)
+{
+ struct request_queue *q = bio->bi_disk->queue;
+ bool nowait = bio->bi_opf & REQ_NOWAIT;
+ blk_qc_t ret;
+
+ if (!generic_make_request_checks(bio))
+ return BLK_QC_T_NONE;
+
+ if (unlikely(blk_queue_enter(q, nowait))) {
+ if (nowait && !blk_queue_dying(q))
+ bio->bi_status = BLK_STS_AGAIN;
+ else
+ bio->bi_status = BLK_STS_IOERR;
+ bio_endio(bio);
+ return BLK_QC_T_NONE;
+ }
+
+ ret = q->make_request_fn(q, bio);
+ blk_queue_exit(q);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(direct_make_request);
+
+/**
* submit_bio - submit a bio to the block device layer for I/O
* @bio: The &struct bio which describes the I/O
*