[Qemu-devel] [PATCH 04/13] qed: extract qed_start_allocating_write()

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

Copy-on-read requests are a form of allocating write and will need to be
queued like other allocating writes.  This patch extracts the request
queuing code for allocating writes so that it can be reused for
copy-on-read in a later patch.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 block/qed.c |   32 ++++++++++++++++++++++++++------
 1 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/block/qed.c b/block/qed.c
index 565bbc1..cc193ad 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1097,14 +1097,15 @@ static bool qed_should_set_need_check(BDRVQEDState *s)
 }
 
 /**
- * Write new data cluster
+ * Start an allocating write request or queue it
  *
- * @acb:        Write request
- * @len:        Length in bytes
+ * @ret:        true if request can proceed, false if queued
  *
- * This path is taken when writing to previously unallocated clusters.
+ * If a request is queued this function returns false and the caller should
+ * return.  When it becomes time for the request to proceed the qed_aio_next()
+ * function will be called.
  */
-static void qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
+static bool qed_start_allocating_write(QEDAIOCB *acb)
 {
     BDRVQEDState *s = acb_to_s(acb);
 
@@ -1119,7 +1120,26 @@ static void qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
     }
     if (acb != QSIMPLEQ_FIRST(&s->allocating_write_reqs) ||
         s->allocating_write_reqs_plugged) {
-        return; /* wait for existing request to finish */
+        return false;
+    }
+    return true;
+}
+
+/**
+ * Write new data cluster
+ *
+ * @acb:        Write request
+ * @len:        Length in bytes
+ *
+ * This path is taken when writing to previously unallocated clusters.
+ */
+static void qed_aio_write_alloc(QEDAIOCB *acb, size_t len)
+{
+    BDRVQEDState *s = acb_to_s(acb);
+    BlockDriverCompletionFunc *cb;
+
+    if (!qed_start_allocating_write(acb)) {
+        return;
     }
 
     acb->cur_nclusters = qed_bytes_to_clusters(s,
-- 
1.7.5.3