qed: Make qed_read_backing_file() synchronous

Note that this code is generally not running in coroutine context, so
this is an actual blocking synchronous operation. We'll fix this in a
moment.

Signed-off-by: Kevin Wolf <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
Reviewed-by: Stefan Hajnoczi <[email protected]>

diff --git a/block/qed.c b/block/qed.c
index 290cbcd6f2bb129ab5072b6203133e733d0f9901..1105f19de691f8fb112ae689f4283cd8144c07a4 100644 (file)
--- a/block/qed.c
+++ b/block/qed.c
@@ -808,13 +808,13 @@ static BDRVQEDState *acb_to_s(QEDAIOCB *acb)
  * This function reads qiov->size bytes starting at pos from the backing file.
  * If there is no backing file then zeroes are read.
  */
  * This function reads qiov->size bytes starting at pos from the backing file.
  * If there is no backing file then zeroes are read.
  */

-static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
-                                  QEMUIOVector *qiov,
-                                  QEMUIOVector **backing_qiov,
-                                  BlockCompletionFunc *cb, void *opaque)
+static int qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
+                                 QEMUIOVector *qiov,
+                                 QEMUIOVector **backing_qiov)

 {
     uint64_t backing_length = 0;
     size_t size;
 {
     uint64_t backing_length = 0;
     size_t size;

+    int ret;

 
     /* If there is a backing file, get its length.  Treat the absence of a
      * backing file like a zero length backing file.
 
     /* If there is a backing file, get its length.  Treat the absence of a
      * backing file like a zero length backing file.


@@ -822,8 +822,7 @@ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
     if (s->bs->backing) {
         int64_t l = bdrv_getlength(s->bs->backing->bs);
         if (l < 0) {
     if (s->bs->backing) {
         int64_t l = bdrv_getlength(s->bs->backing->bs);
         if (l < 0) {

-            cb(opaque, l);
-            return;
+            return l;

         }
         backing_length = l;
     }
         }
         backing_length = l;
     }


@@ -836,8 +835,7 @@ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
 
     /* Complete now if there are no backing file sectors to read */
     if (pos >= backing_length) {
 
     /* Complete now if there are no backing file sectors to read */
     if (pos >= backing_length) {

-        cb(opaque, 0);
-        return;
+        return 0;

     }
 
     /* If the read straddles the end of the backing file, shorten it */
     }
 
     /* If the read straddles the end of the backing file, shorten it */


@@ -849,8 +847,11 @@ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
     qemu_iovec_concat(*backing_qiov, qiov, 0, size);
 
     BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO);
     qemu_iovec_concat(*backing_qiov, qiov, 0, size);
 
     BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO);

-    bdrv_aio_readv(s->bs->backing, pos / BDRV_SECTOR_SIZE,
-                   *backing_qiov, size / BDRV_SECTOR_SIZE, cb, opaque);
+    ret = bdrv_preadv(s->bs->backing, pos, *backing_qiov);
+    if (ret < 0) {
+        return ret;
+    }
+    return 0;

 }
 
 typedef struct {
 }
 
 typedef struct {


@@ -907,6 +908,7 @@ static void qed_copy_from_backing_file(BDRVQEDState *s, uint64_t pos,
                                        void *opaque)
 {
     CopyFromBackingFileCB *copy_cb;
                                        void *opaque)
 {
     CopyFromBackingFileCB *copy_cb;

+    int ret;

 
     /* Skip copy entirely if there is no work to do */
     if (len == 0) {
 
     /* Skip copy entirely if there is no work to do */
     if (len == 0) {


@@ -922,8 +924,9 @@ static void qed_copy_from_backing_file(BDRVQEDState *s, uint64_t pos,
     copy_cb->iov.iov_len = len;
     qemu_iovec_init_external(&copy_cb->qiov, &copy_cb->iov, 1);
 
     copy_cb->iov.iov_len = len;
     qemu_iovec_init_external(&copy_cb->qiov, &copy_cb->iov, 1);
 

-    qed_read_backing_file(s, pos, &copy_cb->qiov, &copy_cb->backing_qiov,
-                          qed_copy_from_backing_file_write, copy_cb);
+    ret = qed_read_backing_file(s, pos, &copy_cb->qiov,
+                                &copy_cb->backing_qiov);
+    qed_copy_from_backing_file_write(copy_cb, ret);

 }
 
 /**
 }
 
 /**


@@ -1366,8 +1369,9 @@ static void qed_aio_read_data(void *opaque, int ret,
         qed_aio_start_io(acb);
         return;
     } else if (ret != QED_CLUSTER_FOUND) {
         qed_aio_start_io(acb);
         return;
     } else if (ret != QED_CLUSTER_FOUND) {

-        qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov,
-                              &acb->backing_qiov, qed_aio_next_io_cb, acb);
+        ret = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov,
+                                    &acb->backing_qiov);
+        qed_aio_next_io(acb, ret);

         return;
     }
 
         return;
     }