[Qemu-devel] [PATCH v2 1/1] qemu-img: wait for convert coroutines to complete

[Anton Nefedov <anton.nefedov@virtuozzo.com>]

On error path (like i/o error in one of the coroutines), it's required to
  - wait for coroutines completion before cleaning the common structures
  - reenter dependent coroutines so they ever finish

Introduced in 2d9187bc65.

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
---
 qemu-img.c | 44 +++++++++++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 17 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index b220cf7..24950c1 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1735,6 +1735,27 @@ static int coroutine_fn convert_co_write(ImgConvertState *s, int64_t sector_num,
     return 0;
 }
 
+static void coroutine_fn convert_reenter_waiting(ImgConvertState *s,
+                                                 uint64_t wr_offs)
+{
+    int i;
+    if (s->wr_in_order) {
+        /* reenter the coroutine that might have waited
+         * for the write to complete */
+        for (i = 0; i < s->num_coroutines; i++) {
+            if (s->co[i] && s->wait_sector_num[i] == wr_offs) {
+                /*
+                 * A -> B -> A cannot occur because A has
+                 * s->wait_sector_num[i] == -1 during A -> B.  Therefore
+                 * B will never enter A during this time window.
+                 */
+                qemu_coroutine_enter(s->co[i]);
+                break;
+            }
+        }
+    }
+}
+
 static void coroutine_fn convert_co_do_copy(void *opaque)
 {
     ImgConvertState *s = opaque;
@@ -1792,6 +1813,7 @@ static void coroutine_fn convert_co_do_copy(void *opaque)
                 error_report("error while reading sector %" PRId64
                              ": %s", sector_num, strerror(-ret));
                 s->ret = ret;
+                convert_reenter_waiting(s, sector_num + n);
                 goto out;
             }
         } else if (!s->min_sparse && status == BLK_ZERO) {
@@ -1803,6 +1825,7 @@ static void coroutine_fn convert_co_do_copy(void *opaque)
             /* keep writes in order */
             while (s->wr_offs != sector_num) {
                 if (s->ret != -EINPROGRESS) {
+                    convert_reenter_waiting(s, sector_num + n);
                     goto out;
                 }
                 s->wait_sector_num[index] = sector_num;
@@ -1816,25 +1839,12 @@ static void coroutine_fn convert_co_do_copy(void *opaque)
             error_report("error while writing sector %" PRId64
                          ": %s", sector_num, strerror(-ret));
             s->ret = ret;
+            convert_reenter_waiting(s, sector_num + n);
             goto out;
         }
 
-        if (s->wr_in_order) {
-            /* reenter the coroutine that might have waited
-             * for this write to complete */
-            s->wr_offs = sector_num + n;
-            for (i = 0; i < s->num_coroutines; i++) {
-                if (s->co[i] && s->wait_sector_num[i] == s->wr_offs) {
-                    /*
-                     * A -> B -> A cannot occur because A has
-                     * s->wait_sector_num[i] == -1 during A -> B.  Therefore
-                     * B will never enter A during this time window.
-                     */
-                    qemu_coroutine_enter(s->co[i]);
-                    break;
-                }
-            }
-        }
+        s->wr_offs = sector_num + n;
+        convert_reenter_waiting(s, s->wr_offs);
     }
 
 out:
@@ -1899,7 +1909,7 @@ static int convert_do_copy(ImgConvertState *s)
         qemu_coroutine_enter(s->co[i]);
     }
 
-    while (s->ret == -EINPROGRESS) {
+    while (s->running_coroutines) {
         main_loop_wait(false);
     }
 
-- 
2.7.4