blockdev: Split monitor reference from BB creation

Before this patch, blk_new() automatically assigned a name to the new BlockBackend and considered it referenced by the monitor. This patch removes the implicit monitor_add_blk() call from blk_new() (and consequently the monitor_remove_blk() call from blk_delete(), too) and thus blk_new() (and related functions) no longer take a BB name argument. In fact, there is only a single point where blk_new()/blk_new_open() is called and the new BB is monitor-owned, and that is in blockdev_init(). Besides thus relieving us from having to invent names for all of the BBs we use in qemu-img, this fixes a bug where qemu cannot create a new image if there already is a monitor-owned BB named "image". If a BB and its BDS tree are created in a single operation, as of this patch the BDS tree will be created before the BB is given a name (whereas it was the other way around before). This results in minor change to the output of iotest 087, whose reference output is amended accordingly. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
intel · Mar 17, 2016 · efaa7c4 · efaa7c4
1 parent e5e7855
commit efaa7c4
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Showing 18 changed files with 68 additions and 76 deletions.
diff --git a/block/block-backend.c b/block/block-backend.c
@@ -80,41 +80,32 @@ static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
     QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
 
 /*
- * Create a new BlockBackend with @name, with a reference count of one.
- * @name must not be null or empty.
- * Fail if a BlockBackend with this name already exists.
+ * Create a new BlockBackend with a reference count of one.
  * Store an error through @errp on failure, unless it's null.
  * Return the new BlockBackend on success, null on failure.
  */
-BlockBackend *blk_new(const char *name, Error **errp)
+BlockBackend *blk_new(Error **errp)
 {
     BlockBackend *blk;
 
     blk = g_new0(BlockBackend, 1);
     blk->refcnt = 1;
     notifier_list_init(&blk->remove_bs_notifiers);
     notifier_list_init(&blk->insert_bs_notifiers);
-
     QTAILQ_INSERT_TAIL(&block_backends, blk, link);
-
-    if (!monitor_add_blk(blk, name, errp)) {
-        blk_unref(blk);
-        return NULL;
-    }
-
     return blk;
 }
 
 /*
  * Create a new BlockBackend with a new BlockDriverState attached.
  * Otherwise just like blk_new(), which see.
  */
-BlockBackend *blk_new_with_bs(const char *name, Error **errp)
+BlockBackend *blk_new_with_bs(Error **errp)
 {
     BlockBackend *blk;
     BlockDriverState *bs;
 
-    blk = blk_new(name, errp);
+    blk = blk_new(errp);
     if (!blk) {
         return NULL;
     }
@@ -137,14 +128,13 @@ BlockBackend *blk_new_with_bs(const char *name, Error **errp)
  * though, so callers of this function have to be able to specify @filename and
  * @flags.
  */
-BlockBackend *blk_new_open(const char *name, const char *filename,
-                           const char *reference, QDict *options, int flags,
-                           Error **errp)
+BlockBackend *blk_new_open(const char *filename, const char *reference,
+                           QDict *options, int flags, Error **errp)
 {
     BlockBackend *blk;
     int ret;
 
-    blk = blk_new_with_bs(name, errp);
+    blk = blk_new_with_bs(errp);
     if (!blk) {
         QDECREF(options);
         return NULL;
@@ -161,8 +151,6 @@ BlockBackend *blk_new_open(const char *name, const char *filename,
 
 static void blk_delete(BlockBackend *blk)
 {
-    monitor_remove_blk(blk);
-
     assert(!blk->refcnt);
     assert(!blk->name);
     assert(!blk->dev);

diff --git a/block/parallels.c b/block/parallels.c
@@ -478,7 +478,7 @@ static int parallels_create(const char *filename, QemuOpts *opts, Error **errp)
         return ret;
     }
 
-    file = blk_new_open("image", filename, NULL, NULL,
+    file = blk_new_open(filename, NULL, NULL,
                         BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                         &local_err);
     if (file == NULL) {

diff --git a/block/qcow.c b/block/qcow.c
@@ -793,7 +793,7 @@ static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
         goto cleanup;
     }
 
-    qcow_blk = blk_new_open("image", filename, NULL, NULL,
+    qcow_blk = blk_new_open(filename, NULL, NULL,
                             BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                             &local_err);
     if (qcow_blk == NULL) {

diff --git a/block/qcow2.c b/block/qcow2.c
@@ -2159,7 +2159,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
         return ret;
     }
 
-    blk = blk_new_open("image", filename, NULL, NULL,
+    blk = blk_new_open(filename, NULL, NULL,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                        &local_err);
     if (blk == NULL) {
@@ -2224,7 +2224,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
      */
     options = qdict_new();
     qdict_put(options, "driver", qstring_from_str("qcow2"));
-    blk = blk_new_open("image-qcow2", filename, NULL, options,
+    blk = blk_new_open(filename, NULL, options,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH,
                        &local_err);
     if (blk == NULL) {
@@ -2286,7 +2286,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
     /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */
     options = qdict_new();
     qdict_put(options, "driver", qstring_from_str("qcow2"));
-    blk = blk_new_open("image-flush", filename, NULL, options,
+    blk = blk_new_open(filename, NULL, options,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_BACKING,
                        &local_err);
     if (blk == NULL) {

diff --git a/block/qed.c b/block/qed.c
@@ -574,7 +574,7 @@ static int qed_create(const char *filename, uint32_t cluster_size,
         return ret;
     }
 
-    blk = blk_new_open("image", filename, NULL, NULL,
+    blk = blk_new_open(filename, NULL, NULL,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                        &local_err);
     if (blk == NULL) {

diff --git a/block/sheepdog.c b/block/sheepdog.c
@@ -1646,7 +1646,7 @@ static int sd_prealloc(const char *filename, Error **errp)
     void *buf = NULL;
     int ret;
 
-    blk = blk_new_open("image-prealloc", filename, NULL, NULL,
+    blk = blk_new_open(filename, NULL, NULL,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                        errp);
     if (blk == NULL) {
@@ -1843,7 +1843,7 @@ static int sd_create(const char *filename, QemuOpts *opts,
             goto out;
         }
 
-        blk = blk_new_open("backing", backing_file, NULL, NULL,
+        blk = blk_new_open(backing_file, NULL, NULL,
                            BDRV_O_PROTOCOL | BDRV_O_CACHE_WB, errp);
         if (blk == NULL) {
             ret = -EIO;

diff --git a/block/vdi.c b/block/vdi.c
@@ -768,7 +768,7 @@ static int vdi_create(const char *filename, QemuOpts *opts, Error **errp)
         goto exit;
     }
 
-    blk = blk_new_open("image", filename, NULL, NULL,
+    blk = blk_new_open(filename, NULL, NULL,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                        &local_err);
     if (blk == NULL) {

diff --git a/block/vhdx.c b/block/vhdx.c
@@ -1838,7 +1838,7 @@ static int vhdx_create(const char *filename, QemuOpts *opts, Error **errp)
         goto exit;
     }
 
-    blk = blk_new_open("image", filename, NULL, NULL,
+    blk = blk_new_open(filename, NULL, NULL,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                        &local_err);
     if (blk == NULL) {

diff --git a/block/vmdk.c b/block/vmdk.c
@@ -1661,7 +1661,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
         goto exit;
     }
 
-    blk = blk_new_open("extent", filename, NULL, NULL,
+    blk = blk_new_open(filename, NULL, NULL,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                        &local_err);
     if (blk == NULL) {
@@ -1946,7 +1946,7 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp)
             goto exit;
         }
 
-        blk = blk_new_open("backing", full_backing, NULL, NULL,
+        blk = blk_new_open(full_backing, NULL, NULL,
                            BDRV_O_NO_BACKING | BDRV_O_CACHE_WB, errp);
         g_free(full_backing);
         if (blk == NULL) {
@@ -2018,7 +2018,7 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp)
         }
     }
 
-    new_blk = blk_new_open("descriptor", filename, NULL, NULL,
+    new_blk = blk_new_open(filename, NULL, NULL,
                            BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                            &local_err);
     if (new_blk == NULL) {

diff --git a/block/vpc.c b/block/vpc.c
@@ -888,7 +888,7 @@ static int vpc_create(const char *filename, QemuOpts *opts, Error **errp)
         goto out;
     }
 
-    blk = blk_new_open("image", filename, NULL, NULL,
+    blk = blk_new_open(filename, NULL, NULL,
                        BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
                        &local_err);
     if (blk == NULL) {

diff --git a/blockdev.c b/blockdev.c
@@ -147,6 +147,7 @@ void blockdev_auto_del(BlockBackend *blk)
     DriveInfo *dinfo = blk_legacy_dinfo(blk);
 
     if (dinfo && dinfo->auto_del) {
+        monitor_remove_blk(blk);
         blk_unref(blk);
     }
 }
@@ -561,7 +562,7 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
     if ((!file || !*file) && !qdict_size(bs_opts)) {
         BlockBackendRootState *blk_rs;
 
-        blk = blk_new(qemu_opts_id(opts), errp);
+        blk = blk_new(errp);
         if (!blk) {
             goto early_err;
         }
@@ -597,8 +598,7 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
             bdrv_flags |= BDRV_O_INACTIVE;
         }
 
-        blk = blk_new_open(qemu_opts_id(opts), file, NULL, bs_opts, bdrv_flags,
-                           errp);
+        blk = blk_new_open(file, NULL, bs_opts, bdrv_flags, errp);
         if (!blk) {
             goto err_no_bs_opts;
         }
@@ -630,6 +630,12 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
 
     blk_set_on_error(blk, on_read_error, on_write_error);
 
+    if (!monitor_add_blk(blk, qemu_opts_id(opts), errp)) {
+        blk_unref(blk);
+        blk = NULL;
+        goto err_no_bs_opts;
+    }
+
 err_no_bs_opts:
     qemu_opts_del(opts);
     QDECREF(interval_dict);
@@ -2859,6 +2865,8 @@ void hmp_drive_del(Monitor *mon, const QDict *qdict)
         blk_remove_bs(blk);
     }
 
+    monitor_remove_blk(blk);
+
     /* if we have a device attached to this BlockDriverState
      * then we need to make the drive anonymous until the device
      * can be removed.  If this is a drive with no device backing
@@ -3976,6 +3984,7 @@ void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
 
     if (bs && bdrv_key_required(bs)) {
         if (blk) {
+            monitor_remove_blk(blk);
             blk_unref(blk);
         } else {
             QTAILQ_REMOVE(&monitor_bdrv_states, bs, monitor_list);
@@ -4005,6 +4014,7 @@ void qmp_x_blockdev_del(bool has_id, const char *id,
     }
 
     if (has_id) {
+        /* blk_by_name() never returns a BB that is not owned by the monitor */
         blk = blk_by_name(id);
         if (!blk) {
             error_setg(errp, "Cannot find block backend %s", id);
@@ -4052,6 +4062,7 @@ void qmp_x_blockdev_del(bool has_id, const char *id,
     }
 
     if (blk) {
+        monitor_remove_blk(blk);
         blk_unref(blk);
     } else {
         QTAILQ_REMOVE(&monitor_bdrv_states, bs, monitor_list);

diff --git a/device-hotplug.c b/device-hotplug.c
@@ -84,6 +84,8 @@ void hmp_drive_add(Monitor *mon, const QDict *qdict)
 
 err:
     if (dinfo) {
-        blk_unref(blk_by_legacy_dinfo(dinfo));
+        BlockBackend *blk = blk_by_legacy_dinfo(dinfo);
+        monitor_remove_blk(blk);
+        blk_unref(blk);
     }
 }
diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
@@ -917,7 +917,7 @@ static int blk_connect(struct XenDevice *xendev)
 
         /* setup via xenbus -> create new block driver instance */
         xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
-        blkdev->blk = blk_new_open(blkdev->dev, blkdev->filename, NULL, options,
+        blkdev->blk = blk_new_open(blkdev->filename, NULL, options,
                                    qflags, &local_err);
         if (!blkdev->blk) {
             xen_be_printf(&blkdev->xendev, 0, "error: %s\n",

diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
@@ -59,11 +59,10 @@ typedef struct BlockDevOps {
     void (*resize_cb)(void *opaque);
 } BlockDevOps;
 
-BlockBackend *blk_new(const char *name, Error **errp);
-BlockBackend *blk_new_with_bs(const char *name, Error **errp);
-BlockBackend *blk_new_open(const char *name, const char *filename,
-                           const char *reference, QDict *options, int flags,
-                           Error **errp);
+BlockBackend *blk_new(Error **errp);
+BlockBackend *blk_new_with_bs(Error **errp);
+BlockBackend *blk_new_open(const char *filename, const char *reference,
+                           QDict *options, int flags, Error **errp);
 int blk_get_refcnt(BlockBackend *blk);
 void blk_ref(BlockBackend *blk);
 void blk_unref(BlockBackend *blk);