block: Add BlockBackend.ctx

This adds a new parameter to blk_new() which requires its callers to
declare from which AioContext this BlockBackend is going to be used (or
the locks of which AioContext need to be taken anyway).

The given context is only stored and kept up to date when changing
AioContexts. Actually applying the stored AioContext to the root node
is saved for another commit.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

5 files changed, 7 insertions, 5 deletions

diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 6f19f127a5..37ccedc9f7 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -538,7 +538,7 @@ static void floppy_drive_realize(DeviceState *qdev, Error **errp)
 
     if (!dev->conf.blk) {
         /* Anonymous BlockBackend for an empty drive */
-        dev->conf.blk = blk_new(0, BLK_PERM_ALL);
+        dev->conf.blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
         ret = blk_attach_dev(dev->conf.blk, qdev);
         assert(ret == 0);
     }
diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index ef635be4c2..31b0f5ccc8 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -609,7 +609,7 @@ static void xen_cdrom_realize(XenBlockDevice *blockdev, Error **errp)
         int rc;
 
         /* Set up an empty drive */
-        conf->blk = blk_new(0, BLK_PERM_ALL);
+        conf->blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
 
         rc = blk_attach_dev(conf->blk, DEVICE(blockdev));
         if (!rc) {
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index b45a7ef54b..42e048f190 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -80,7 +80,9 @@ static void parse_drive(DeviceState *dev, const char *str, void **ptr,
     if (!blk) {
         BlockDriverState *bs = bdrv_lookup_bs(NULL, str, NULL);
         if (bs) {
-            blk = blk_new(0, BLK_PERM_ALL);
+            /* BlockBackends of devices start in the main context and are only
+             * later moved into another context if the device supports that. */
+            blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
             blk_created = true;
 
             ret = blk_insert_bs(blk, bs, errp);
diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
index 573b022e1e..360cd20bd8 100644
--- a/hw/ide/qdev.c
+++ b/hw/ide/qdev.c
@@ -168,7 +168,7 @@ static void ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind, Error **errp)
             return;
         } else {
             /* Anonymous BlockBackend for an empty drive */
-            dev->conf.blk = blk_new(0, BLK_PERM_ALL);
+            dev->conf.blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
             ret = blk_attach_dev(dev->conf.blk, &dev->qdev);
             assert(ret == 0);
         }
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index e7e865ab3b..91c5a8b1ac 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -2417,7 +2417,7 @@ static void scsi_cd_realize(SCSIDevice *dev, Error **errp)
     if (!dev->conf.blk) {
         /* Anonymous BlockBackend for an empty drive. As we put it into
          * dev->conf, qdev takes care of detaching on unplug. */
-        dev->conf.blk = blk_new(0, BLK_PERM_ALL);
+        dev->conf.blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
         ret = blk_attach_dev(dev->conf.blk, &dev->qdev);
         assert(ret == 0);
     }