Re: blk-mq request allocation stalls

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 01/12/2015 11:35 AM, Keith Busch wrote:
On Mon, 12 Jan 2015, Keith Busch wrote:
Oh, let's look at "__blk_rq_prep_clone". dm calls that after
blk_get_request() for the blk-mq based multipath types and overrides the
destinations cmd_flags with the source's even though the source was not
allocated from a blk-mq based queue, much less a shared tag.

Untested patch. This will also preserve the failfast cmd_flag dm-mpath
set after allocating.

---
diff --git a/block/blk-core.c b/block/blk-core.c
index 7e78931..6201090 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2895,7 +2895,10 @@ EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
  static void __blk_rq_prep_clone(struct request *dst, struct request *src)
  {
      dst->cpu = src->cpu;
-    dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
+    if (dst->q->mq_ops)
+        dst->cmd_flags |= (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
+    else
+        dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;

Making the two cases different is a bit... nonsensical. We should do this for both cases, if safe, or move the MQ_INFLIGHT flag and expand the CLONE_MASK.

--
Jens Axboe

--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel



[Index of Archives]     [DM Crypt]     [Fedora Desktop]     [ATA RAID]     [Fedora Marketing]     [Fedora Packaging]     [Fedora SELinux]     [Yosemite Discussion]     [KDE Users]     [Fedora Docs]

  Powered by Linux