[Qemu-devel] [PATCH 12/14] backup: Use BlockBackend for I/O

[Kevin Wolf <kwolf@redhat.com>]

This changes the backup block job to use the job's BlockBackend for
performing its I/O. job->bs isn't used by the backup code any more
afterwards.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/backup.c                 | 42 ++++++++++++++++++++++--------------------
 block/block-backend.c          | 14 ++++++++++++++
 block/io.c                     |  9 ---------
 blockdev.c                     |  4 +---
 include/block/block.h          |  2 --
 include/sysemu/block-backend.h |  2 ++
 trace-events                   |  2 +-
 7 files changed, 40 insertions(+), 35 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 670ba50..ba9eb42 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -36,7 +36,7 @@ typedef struct CowRequest {
 
 typedef struct BackupBlockJob {
     BlockJob common;
-    BlockDriverState *target;
+    BlockBackend *target;
     /* bitmap for sync=incremental */
     BdrvDirtyBitmap *sync_bitmap;
     MirrorSyncMode sync_mode;
@@ -99,7 +99,7 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
                                       bool *error_is_read,
                                       bool is_write_notifier)
 {
-    BlockDriverState *bs = job->common.bs;
+    BlockBackend *blk = job->common.blk;
     CowRequest cow_request;
     struct iovec iov;
     QEMUIOVector bounce_qiov;
@@ -132,19 +132,18 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
                 start * sectors_per_cluster);
 
         if (!bounce_buffer) {
-            bounce_buffer = qemu_blockalign(bs, job->cluster_size);
+            bounce_buffer = blk_blockalign(blk, job->cluster_size);
         }
         iov.iov_base = bounce_buffer;
         iov.iov_len = n * BDRV_SECTOR_SIZE;
         qemu_iovec_init_external(&bounce_qiov, &iov, 1);
 
         if (is_write_notifier) {
-            ret = bdrv_co_readv_no_serialising(bs,
-                                           start * sectors_per_cluster,
-                                           n, &bounce_qiov);
+            ret = blk_co_readv_no_serialising(blk, start * sectors_per_cluster,
+                                              n, &bounce_qiov);
         } else {
-            ret = bdrv_co_readv(bs, start * sectors_per_cluster, n,
-                                &bounce_qiov);
+            ret = blk_co_readv(blk, start * sectors_per_cluster, n,
+                               &bounce_qiov);
         }
         if (ret < 0) {
             trace_backup_do_cow_read_fail(job, start, ret);
@@ -155,13 +154,13 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
         }
 
         if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
-            ret = bdrv_co_write_zeroes(job->target,
+            ret = blk_co_write_zeroes(job->target,
                                        start * sectors_per_cluster,
                                        n, BDRV_REQ_MAY_UNMAP);
         } else {
-            ret = bdrv_co_writev(job->target,
-                                 start * sectors_per_cluster, n,
-                                 &bounce_qiov);
+            ret = blk_co_writev(job->target,
+                                start * sectors_per_cluster, n,
+                                &bounce_qiov);
         }
         if (ret < 0) {
             trace_backup_do_cow_write_fail(job, start, ret);
@@ -203,7 +202,7 @@ static int coroutine_fn backup_before_write_notify(
     int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
     int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
 
-    assert(req->bs == job->common.bs);
+    assert(req->bs == blk_bs(job->common.blk));
     assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
     assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 
@@ -224,7 +223,7 @@ static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
 static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
 {
     BdrvDirtyBitmap *bm;
-    BlockDriverState *bs = job->common.bs;
+    BlockDriverState *bs = blk_bs(job->common.blk);
 
     if (ret < 0 || block_job_is_cancelled(&job->common)) {
         /* Merge the successor back into the parent, delete nothing. */
@@ -282,7 +281,7 @@ static void backup_complete(BlockJob *job, void *opaque)
     BackupBlockJob *s = container_of(job, BackupBlockJob, common);
     BackupCompleteData *data = opaque;
 
-    bdrv_unref(s->target);
+    blk_unref(s->target);
 
     block_job_completed(job, data->ret);
     g_free(data);
@@ -378,8 +377,8 @@ static void coroutine_fn backup_run(void *opaque)
 {
     BackupBlockJob *job = opaque;
     BackupCompleteData *data;
-    BlockDriverState *bs = job->common.bs;
-    BlockDriverState *target = job->target;
+    BlockDriverState *bs = blk_bs(job->common.blk);
+    BlockBackend *target = job->target;
     int64_t start, end;
     int64_t sectors_per_cluster = cluster_size_sectors(job);
     int ret = 0;
@@ -468,7 +467,7 @@ static void coroutine_fn backup_run(void *opaque)
     qemu_co_rwlock_unlock(&job->flush_rwlock);
     g_free(job->done_bitmap);
 
-    bdrv_op_unblock_all(target, job->common.blocker);
+    bdrv_op_unblock_all(blk_bs(target), job->common.blocker);
 
     data = g_malloc(sizeof(*data));
     data->ret = ret;
@@ -548,9 +547,11 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
         goto error;
     }
 
+    job->target = blk_new(&error_abort);
+    blk_insert_bs(job->target, target);
+
     job->on_source_error = on_source_error;
     job->on_target_error = on_target_error;
-    job->target = target;
     job->sync_mode = sync_mode;
     job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
                        sync_bitmap : NULL;
@@ -558,7 +559,7 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
     /* If there is no backing file on the target, we cannot rely on COW if our
      * backup cluster size is smaller than the target cluster size. Even for
      * targets with a backing file, try to avoid COW if possible. */
-    ret = bdrv_get_info(job->target, &bdi);
+    ret = bdrv_get_info(target, &bdi);
     if (ret < 0 && !target->backing) {
         error_setg_errno(errp, -ret,
             "Couldn't determine the cluster size of the target image, "
@@ -585,6 +586,7 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
         bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
     }
     if (job) {
+        blk_unref(job->target);
         block_job_unref(&job->common);
     }
 }
diff --git a/block/block-backend.c b/block/block-backend.c
index 8dc3aa5..2b3c55f 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -807,6 +807,20 @@ int coroutine_fn blk_co_readv(BlockBackend *blk, int64_t sector_num,
                          nb_sectors << BDRV_SECTOR_BITS, qiov, 0);
 }
 
+int coroutine_fn blk_co_readv_no_serialising(BlockBackend *blk,
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
+{
+    trace_blk_co_readv_no_serialising(blk, blk_bs(blk), sector_num, nb_sectors);
+
+    if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
+        return -EINVAL;
+    }
+
+    return blk_co_preadv(blk, sector_num << BDRV_SECTOR_BITS,
+                         nb_sectors << BDRV_SECTOR_BITS, qiov,
+                         BDRV_REQ_NO_SERIALISING);
+}
+
 int coroutine_fn blk_co_copy_on_readv(BlockBackend *blk,
     int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
 {
diff --git a/block/io.c b/block/io.c
index 8280e14..eeb0e4c 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1093,15 +1093,6 @@ int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
     return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov, 0);
 }
 
-int coroutine_fn bdrv_co_readv_no_serialising(BlockDriverState *bs,
-    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
-{
-    trace_bdrv_co_readv_no_serialising(bs, sector_num, nb_sectors);
-
-    return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov,
-                            BDRV_REQ_NO_SERIALISING);
-}
-
 #define MAX_WRITE_ZEROES_BOUNCE_BUFFER 32768
 
 static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
diff --git a/blockdev.c b/blockdev.c
index 7a0196f..fa381ce 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3268,8 +3268,8 @@ static void do_drive_backup(const char *device, const char *target,
     backup_start(bs, target_bs, speed, sync, bmap,
                  on_source_error, on_target_error,
                  block_job_cb, bs, txn, &local_err);
+    bdrv_unref(target_bs);
     if (local_err != NULL) {
-        bdrv_unref(target_bs);
         error_propagate(errp, local_err);
         goto out;
     }
@@ -3353,12 +3353,10 @@ void do_blockdev_backup(const char *device, const char *target,
     }
     target_bs = blk_bs(target_blk);
 
-    bdrv_ref(target_bs);
     bdrv_set_aio_context(target_bs, aio_context);
     backup_start(bs, target_bs, speed, sync, NULL, on_source_error,
                  on_target_error, block_job_cb, bs, txn, &local_err);
     if (local_err != NULL) {
-        bdrv_unref(target_bs);
         error_propagate(errp, local_err);
     }
 out:
diff --git a/include/block/block.h b/include/block/block.h
index 39b5812..8e7d348 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -243,8 +243,6 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
     const void *buf, int count);
 int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
     int nb_sectors, QEMUIOVector *qiov);
-int coroutine_fn bdrv_co_readv_no_serialising(BlockDriverState *bs,
-    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
 int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,
     int nb_sectors, QEMUIOVector *qiov);
 /*
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index d98552c..715fd9e 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -118,6 +118,8 @@ int blk_read_unthrottled(BlockBackend *blk, int64_t sector_num, uint8_t *buf,
                          int nb_sectors);
 int coroutine_fn blk_co_readv(BlockBackend *blk, int64_t sector_num,
                               int nb_sectors, QEMUIOVector *qiov);
+int coroutine_fn blk_co_readv_no_serialising(BlockBackend *blk,
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
 int coroutine_fn blk_co_copy_on_readv(BlockBackend *blk,
     int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
 int coroutine_fn blk_co_writev(BlockBackend *blk, int64_t sector_num,
diff --git a/trace-events b/trace-events
index 3b5cce3..2ee3cb7 100644
--- a/trace-events
+++ b/trace-events
@@ -65,6 +65,7 @@ bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d"
 blk_co_readv(void *blk, void *bs, int64_t sector_num, int nb_sector) "blk %p bs %p sector_num %"PRId64" nb_sectors %d"
 blk_co_writev(void *blk, void *bs, int64_t sector_num, int nb_sector) "blk %p bs %p sector_num %"PRId64" nb_sectors %d"
 blk_co_copy_on_readv(void *blk, void *bs, int64_t sector_num, int nb_sector) "blk %p bs %p sector_num %"PRId64" nb_sectors %d"
+blk_co_readv_no_serialising(void *blk, void *bs, int64_t sector_num, int nb_sector) "blk %p bs %p sector_num %"PRId64" nb_sectors %d"
 
 # block/io.c
 bdrv_aio_discard(void *bs, int64_t sector_num, int nb_sectors, void *opaque) "bs %p sector_num %"PRId64" nb_sectors %d opaque %p"
@@ -73,7 +74,6 @@ bdrv_aio_readv(void *bs, int64_t sector_num, int nb_sectors, void *opaque) "bs %
 bdrv_aio_writev(void *bs, int64_t sector_num, int nb_sectors, void *opaque) "bs %p sector_num %"PRId64" nb_sectors %d opaque %p"
 bdrv_aio_write_zeroes(void *bs, int64_t sector_num, int nb_sectors, int flags, void *opaque) "bs %p sector_num %"PRId64" nb_sectors %d flags %#x opaque %p"
 bdrv_co_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
-bdrv_co_readv_no_serialising(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
 bdrv_co_writev(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
 bdrv_co_write_zeroes(void *bs, int64_t sector_num, int nb_sector, int flags) "bs %p sector_num %"PRId64" nb_sectors %d flags %#x"
 bdrv_co_do_copy_on_readv(void *bs, int64_t sector_num, int nb_sectors, int64_t cluster_sector_num, int cluster_nb_sectors) "bs %p sector_num %"PRId64" nb_sectors %d cluster_sector_num %"PRId64" cluster_nb_sectors %d"
-- 
1.8.3.1