Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2019-11-07' into staging

[qemu.git] / block / stream.c

diff --git a/block/stream.c b/block/stream.c
index cd5e2ba9b071d306b870a38e1785bdcae04bd002..5562ccbf577a20ddd520ec080c2608763109f997 100644 (file)
--- a/block/stream.c
+++ b/block/stream.c
@@ -22,11 +22,11 @@
 
 enum {
     /*
-     * Size of data buffer for populating the image file.  This should be large
-     * enough to process multiple clusters in a single call, so that populating
-     * contiguous regions of the image is efficient.
+     * Maximum chunk size to feed to copy-on-read.  This should be
+     * large enough to process multiple clusters in a single call, so
+     * that populating contiguous regions of the image is efficient.
      */
-    STREAM_BUFFER_SIZE = 512 * 1024, /* in bytes */
+    STREAM_CHUNK = 512 * 1024, /* in bytes */
 };
 
 typedef struct StreamBlockJob {
@@ -39,13 +39,12 @@ typedef struct StreamBlockJob {
 } StreamBlockJob;
 
 static int coroutine_fn stream_populate(BlockBackend *blk,
-                                        int64_t offset, uint64_t bytes,
-                                        void *buf)
+                                        int64_t offset, uint64_t bytes)
 {
     assert(bytes < SIZE_MAX);
 
-    /* Copy-on-read the unallocated clusters */
-    return blk_co_pread(blk, offset, bytes, buf, BDRV_REQ_COPY_ON_READ);
+    return blk_co_preadv(blk, offset, bytes, NULL,
+                         BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH);
 }
 
 static void stream_abort(Job *job)
@@ -78,8 +77,8 @@ static int stream_prepare(Job *job)
                 base_fmt = base->drv->format_name;
             }
         }
-        ret = bdrv_change_backing_file(bs, base_id, base_fmt);
         bdrv_set_backing_hd(bs, base, &local_err);
+        ret = bdrv_change_backing_file(bs, base_id, base_fmt);
         if (local_err) {
             error_report_err(local_err);
             return -EPERM;
@@ -117,7 +116,6 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
     int error = 0;
     int ret = 0;
     int64_t n = 0; /* bytes */
-    void *buf;
 
     if (bs == s->bottom) {
         /* Nothing to stream */
@@ -130,8 +128,6 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
     }
     job_progress_set_remaining(&s->common.job, len);
 
-    buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE);
-
     /* Turn on copy-on-read for the whole block device so that guest read
      * requests help us make progress.  Only do this when copying the entire
      * backing chain since the copy-on-read operation does not take base into
@@ -154,7 +150,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
 
         copy = false;
 
-        ret = bdrv_is_allocated(bs, offset, STREAM_BUFFER_SIZE, &n);
+        ret = bdrv_is_allocated(bs, offset, STREAM_CHUNK, &n);
         if (ret == 1) {
             /* Allocated in the top, no need to copy.  */
         } else if (ret >= 0) {
@@ -171,7 +167,7 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
         }
         trace_stream_one_iteration(s, offset, n, ret);
         if (copy) {
-            ret = stream_populate(blk, offset, n, buf);
+            ret = stream_populate(blk, offset, n);
         }
         if (ret < 0) {
             BlockErrorAction action =
@@ -202,8 +198,6 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
         bdrv_disable_copy_on_read(bs);
     }
 
-    qemu_vfree(buf);
-
     /* Do not remove the backing file if an error was there but ignored. */
     return error;
 }
@@ -218,7 +212,6 @@ static const BlockJobDriver stream_job_driver = {
         .abort         = stream_abort,
         .clean         = stream_clean,
         .user_resume   = block_job_user_resume,
-        .drain         = block_job_drain,
     },
 };
 
@@ -284,5 +277,5 @@ fail:
     if (bs_read_only) {
         bdrv_reopen_set_read_only(bs, true, NULL);
     }
-    bdrv_unfreeze_backing_chain(bs, base);
+    bdrv_unfreeze_backing_chain(bs, bottom);
 }