sheepdog: split outstanding list into inflight and pending

outstanding_list_head is used for both pending and inflight requests.
This patch splits it and improves readability.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 24 insertions, 25 deletions

diff --git a/block/sheepdog.c b/block/sheepdog.c
index d4e5e3a..f6cd517 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -259,7 +259,7 @@ typedef struct AIOReq {
     uint8_t flags;
     uint32_t id;
 
-    QLIST_ENTRY(AIOReq) outstanding_aio_siblings;
+    QLIST_ENTRY(AIOReq) aio_siblings;
 } AIOReq;
 
 enum AIOCBState {
@@ -305,7 +305,8 @@ typedef struct BDRVSheepdogState {
     Coroutine *co_recv;
 
     uint32_t aioreq_seq_num;
-    QLIST_HEAD(outstanding_aio_head, AIOReq) outstanding_aio_head;
+    QLIST_HEAD(inflight_aio_head, AIOReq) inflight_aio_head;
+    QLIST_HEAD(pending_aio_head, AIOReq) pending_aio_head;
 } BDRVSheepdogState;
 
 static const char * sd_strerror(int err)
@@ -356,7 +357,7 @@ static const char * sd_strerror(int err)
  * Sheepdog I/O handling:
  *
  * 1. In sd_co_rw_vector, we send the I/O requests to the server and
- *    link the requests to the outstanding_list in the
+ *    link the requests to the inflight_list in the
  *    BDRVSheepdogState.  The function exits without waiting for
  *    receiving the response.
  *
@@ -384,9 +385,6 @@ static inline AIOReq *alloc_aio_req(BDRVSheepdogState *s, SheepdogAIOCB *acb,
     aio_req->flags = flags;
     aio_req->id = s->aioreq_seq_num++;
 
-    QLIST_INSERT_HEAD(&s->outstanding_aio_head, aio_req,
-                      outstanding_aio_siblings);
-
     acb->nr_pending++;
     return aio_req;
 }
@@ -395,7 +393,7 @@ static inline void free_aio_req(BDRVSheepdogState *s, AIOReq *aio_req)
 {
     SheepdogAIOCB *acb = aio_req->aiocb;
 
-    QLIST_REMOVE(aio_req, outstanding_aio_siblings);
+    QLIST_REMOVE(aio_req, aio_siblings);
     g_free(aio_req);
 
     acb->nr_pending--;
@@ -640,22 +638,21 @@ static int coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
  * This function searchs pending requests to the object `oid', and
  * sends them.
  */
-static void coroutine_fn send_pending_req(BDRVSheepdogState *s, uint64_t oid, uint32_t id)
+static void coroutine_fn send_pending_req(BDRVSheepdogState *s, uint64_t oid)
 {
     AIOReq *aio_req, *next;
     SheepdogAIOCB *acb;
     int ret;
 
-    QLIST_FOREACH_SAFE(aio_req, &s->outstanding_aio_head,
-                       outstanding_aio_siblings, next) {
-        if (id == aio_req->id) {
-            continue;
-        }
+    QLIST_FOREACH_SAFE(aio_req, &s->pending_aio_head, aio_siblings, next) {
         if (aio_req->oid != oid) {
             continue;
         }
 
         acb = aio_req->aiocb;
+        /* move aio_req from pending list to inflight one */
+        QLIST_REMOVE(aio_req, aio_siblings);
+        QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
         ret = add_aio_request(s, aio_req, acb->qiov->iov,
                               acb->qiov->niov, 0, acb->aiocb_type);
         if (ret < 0) {
@@ -684,7 +681,7 @@ static void coroutine_fn aio_read_response(void *opaque)
     SheepdogAIOCB *acb;
     unsigned long idx;
 
-    if (QLIST_EMPTY(&s->outstanding_aio_head)) {
+    if (QLIST_EMPTY(&s->inflight_aio_head)) {
         goto out;
     }
 
@@ -695,8 +692,8 @@ static void coroutine_fn aio_read_response(void *opaque)
         goto out;
     }
 
-    /* find the right aio_req from the outstanding_aio list */
-    QLIST_FOREACH(aio_req, &s->outstanding_aio_head, outstanding_aio_siblings) {
+    /* find the right aio_req from the inflight aio list */
+    QLIST_FOREACH(aio_req, &s->inflight_aio_head, aio_siblings) {
         if (aio_req->id == rsp.id) {
             break;
         }
@@ -734,7 +731,7 @@ static void coroutine_fn aio_read_response(void *opaque)
              * create requests are not allowed, so we search the
              * pending requests here.
              */
-            send_pending_req(s, vid_to_data_oid(s->inode.vdi_id, idx), rsp.id);
+            send_pending_req(s, vid_to_data_oid(s->inode.vdi_id, idx));
         }
         break;
     case AIOCB_READ_UDATA:
@@ -786,7 +783,8 @@ static int aio_flush_request(void *opaque)
 {
     BDRVSheepdogState *s = opaque;
 
-    return !QLIST_EMPTY(&s->outstanding_aio_head);
+    return !QLIST_EMPTY(&s->inflight_aio_head) ||
+        !QLIST_EMPTY(&s->pending_aio_head);
 }
 
 static int set_nodelay(int fd)
@@ -1103,7 +1101,8 @@ static int sd_open(BlockDriverState *bs, const char *filename, int flags)
 
     strstart(filename, "sheepdog:", (const char **)&filename);
 
-    QLIST_INIT(&s->outstanding_aio_head);
+    QLIST_INIT(&s->inflight_aio_head);
+    QLIST_INIT(&s->pending_aio_head);
     s->fd = -1;
 
     memset(vdi, 0, sizeof(vdi));
@@ -1465,6 +1464,7 @@ static void coroutine_fn sd_write_done(SheepdogAIOCB *acb)
         iov.iov_len = sizeof(s->inode);
         aio_req = alloc_aio_req(s, acb, vid_to_vdi_oid(s->inode.vdi_id),
                                 data_len, offset, 0, 0, offset);
+        QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
         ret = add_aio_request(s, aio_req, &iov, 1, 0, AIOCB_WRITE_UDATA);
         if (ret) {
             free_aio_req(s, aio_req);
@@ -1533,7 +1533,7 @@ out:
  * Send I/O requests to the server.
  *
  * This function sends requests to the server, links the requests to
- * the outstanding_list in BDRVSheepdogState, and exits without
+ * the inflight_list in BDRVSheepdogState, and exits without
  * waiting the response.  The responses are received in the
  * `aio_read_response' function which is called from the main loop as
  * a fd handler.
@@ -1606,11 +1606,7 @@ static int coroutine_fn sd_co_rw_vector(void *p)
 
         if (create) {
             AIOReq *areq;
-            QLIST_FOREACH(areq, &s->outstanding_aio_head,
-                          outstanding_aio_siblings) {
-                if (areq == aio_req) {
-                    continue;
-                }
+            QLIST_FOREACH(areq, &s->inflight_aio_head, aio_siblings) {
                 if (areq->oid == oid) {
                     /*
                      * Sheepdog cannot handle simultaneous create
@@ -1620,11 +1616,14 @@ static int coroutine_fn sd_co_rw_vector(void *p)
                      */
                     aio_req->flags = 0;
                     aio_req->base_oid = 0;
+                    QLIST_INSERT_HEAD(&s->pending_aio_head, aio_req,
+                                      aio_siblings);
                     goto done;
                 }
             }
         }
 
+        QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
         ret = add_aio_request(s, aio_req, acb->qiov->iov, acb->qiov->niov,
                               create, acb->aiocb_type);
         if (ret < 0) {