Patchwork [v10,03/11] block: Replace in_use with operation blocker

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Submitter Fam Zheng
Date Jan. 8, 2014, 3:42 a.m.
Message ID <1389152570-1815-4-git-send-email-famz@redhat.com>
Download mbox | patch
Permalink /patch/307993/
State New
Headers show

Comments

Fam Zheng - Jan. 8, 2014, 3:42 a.m.
This drops BlockDriverState.in_use with op_blockers:

  - Call bdrv_op_block_all in place of bdrv_set_in_use(bs, 1).
  - Call bdrv_op_unblock_all in place of bdrv_set_in_use(bs, 0).
  - Check bdrv_op_is_blocked() in place of bdrv_in_use(bs).
    The specific types are used, e.g. in place of starting block backup,
    bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP, ...).
  - Check bdrv_op_blocker_is_empty() in place of assert(!bs->in_use).

Note: there is only bdrv_op_block_all and bdrv_op_unblock_all callers at
this moment. So although the checks are specific to op types, this
changes can still be seen as identical logic with previously with
in_use. The difference is error message are improved because of blocker
error info.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block-migration.c               |  7 +++++--
 block.c                         | 24 +++++++-----------------
 blockdev.c                      | 15 ++++++---------
 blockjob.c                      | 14 +++++++++-----
 hw/block/dataplane/virtio-blk.c | 19 ++++++++++++-------
 include/block/block.h           |  2 --
 include/block/block_int.h       |  1 -
 include/block/blockjob.h        |  3 +++
 8 files changed, 42 insertions(+), 43 deletions(-)

Patch

diff --git a/block-migration.c b/block-migration.c
index 897fdba..bf9a25f 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -59,6 +59,7 @@  typedef struct BlkMigDevState {
     unsigned long *aio_bitmap;
     int64_t completed_sectors;
     BdrvDirtyBitmap *dirty_bitmap;
+    Error *blocker;
 } BlkMigDevState;
 
 typedef struct BlkMigBlock {
@@ -346,7 +347,8 @@  static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
         bmds->completed_sectors = 0;
         bmds->shared_base = block_mig_state.shared_base;
         alloc_aio_bitmap(bmds);
-        bdrv_set_in_use(bs, 1);
+        error_setg(&bmds->blocker, "block device is in use by migration");
+        bdrv_op_block_all(bs, bmds->blocker);
         bdrv_ref(bs);
 
         block_mig_state.total_sector_sum += sectors;
@@ -584,7 +586,8 @@  static void blk_mig_cleanup(void)
     blk_mig_lock();
     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
-        bdrv_set_in_use(bmds->bs, 0);
+        bdrv_op_unblock_all(bmds->bs, bmds->blocker);
+        error_free(bmds->blocker);
         bdrv_unref(bmds->bs);
         g_free(bmds->aio_bitmap);
         g_free(bmds);
diff --git a/block.c b/block.c
index 91cda9c..b122154 100644
--- a/block.c
+++ b/block.c
@@ -1621,7 +1621,6 @@  static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
     bs_dest->refcnt             = bs_src->refcnt;
 
     /* job */
-    bs_dest->in_use             = bs_src->in_use;
     bs_dest->job                = bs_src->job;
 
     /* keep the same entry in bdrv_states */
@@ -1653,7 +1652,7 @@  void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
     assert(bs_new->job == NULL);
     assert(bs_new->dev == NULL);
-    assert(bs_new->in_use == 0);
+    assert(bdrv_op_blocker_is_empty(bs_new));
     assert(bs_new->io_limits_enabled == false);
     assert(!throttle_have_timer(&bs_new->throttle_state));
 
@@ -1672,7 +1671,7 @@  void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     /* Check a few fields that should remain attached to the device */
     assert(bs_new->dev == NULL);
     assert(bs_new->job == NULL);
-    assert(bs_new->in_use == 0);
+    assert(bdrv_op_blocker_is_empty(bs_new));
     assert(bs_new->io_limits_enabled == false);
     assert(!throttle_have_timer(&bs_new->throttle_state));
 
@@ -1709,7 +1708,7 @@  static void bdrv_delete(BlockDriverState *bs)
 {
     assert(!bs->dev);
     assert(!bs->job);
-    assert(!bs->in_use);
+    assert(bdrv_op_blocker_is_empty(bs));
     assert(!bs->refcnt);
     assert(QLIST_EMPTY(&bs->dirty_bitmaps));
 
@@ -1891,7 +1890,8 @@  int bdrv_commit(BlockDriverState *bs)
         return -ENOTSUP;
     }
 
-    if (bdrv_in_use(bs) || bdrv_in_use(bs->backing_hd)) {
+    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT, NULL) ||
+        bdrv_op_is_blocked(bs->backing_hd, BLOCK_OP_TYPE_COMMIT, NULL)) {
         return -EBUSY;
     }
 
@@ -2924,8 +2924,9 @@  int bdrv_truncate(BlockDriverState *bs, int64_t offset)
         return -ENOTSUP;
     if (bs->read_only)
         return -EACCES;
-    if (bdrv_in_use(bs))
+    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_RESIZE, NULL)) {
         return -EBUSY;
+    }
     ret = drv->bdrv_truncate(bs, offset);
     if (ret == 0) {
         ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS);
@@ -4705,17 +4706,6 @@  bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
     return true;
 }
 
-void bdrv_set_in_use(BlockDriverState *bs, int in_use)
-{
-    assert(bs->in_use != in_use);
-    bs->in_use = in_use;
-}
-
-int bdrv_in_use(BlockDriverState *bs)
-{
-    return bs->in_use;
-}
-
 void bdrv_iostatus_enable(BlockDriverState *bs)
 {
     bs->iostatus_enabled = true;
diff --git a/blockdev.c b/blockdev.c
index 6a85961..9d36775 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1224,8 +1224,8 @@  static void external_snapshot_prepare(BlkTransactionState *common,
         return;
     }
 
-    if (bdrv_in_use(state->old_bs)) {
-        error_set(errp, QERR_DEVICE_IN_USE, device);
+    if (bdrv_op_is_blocked(state->old_bs,
+                           BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT, errp)) {
         return;
     }
 
@@ -1441,8 +1441,7 @@  exit:
 
 static void eject_device(BlockDriverState *bs, int force, Error **errp)
 {
-    if (bdrv_in_use(bs)) {
-        error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
+    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_EJECT, errp)) {
         return;
     }
     if (!bdrv_dev_has_removable_media(bs)) {
@@ -1643,7 +1642,7 @@  int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
         qerror_report(QERR_DEVICE_NOT_FOUND, id);
         return -1;
     }
-    if (bdrv_in_use(bs)) {
+    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_DRIVE_DEL, NULL)) {
         qerror_report(QERR_DEVICE_IN_USE, id);
         return -1;
     }
@@ -1881,8 +1880,7 @@  void qmp_drive_backup(const char *device, const char *target,
         }
     }
 
-    if (bdrv_in_use(bs)) {
-        error_set(errp, QERR_DEVICE_IN_USE, device);
+    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
         return;
     }
 
@@ -2011,8 +2009,7 @@  void qmp_drive_mirror(const char *device, const char *target,
         }
     }
 
-    if (bdrv_in_use(bs)) {
-        error_set(errp, QERR_DEVICE_IN_USE, device);
+    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR, errp)) {
         return;
     }
 
diff --git a/blockjob.c b/blockjob.c
index 9e5fd5c..f1ff036 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -41,14 +41,16 @@  void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
 {
     BlockJob *job;
 
-    if (bs->job || bdrv_in_use(bs)) {
+    if (bs->job || !bdrv_op_blocker_is_empty(bs)) {
         error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
         return NULL;
     }
     bdrv_ref(bs);
-    bdrv_set_in_use(bs, 1);
-
     job = g_malloc0(driver->instance_size);
+    error_setg(&job->blocker, "block device is in use by block job: %s",
+               BlockJobType_lookup[driver->job_type]);
+    bdrv_op_block_all(bs, job->blocker);
+
     job->driver        = driver;
     job->bs            = bs;
     job->cb            = cb;
@@ -63,8 +65,9 @@  void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
         block_job_set_speed(job, speed, &local_err);
         if (error_is_set(&local_err)) {
             bs->job = NULL;
+            bdrv_op_unblock_all(bs, job->blocker);
+            error_free(job->blocker);
             g_free(job);
-            bdrv_set_in_use(bs, 0);
             error_propagate(errp, local_err);
             return NULL;
         }
@@ -79,8 +82,9 @@  void block_job_completed(BlockJob *job, int ret)
     assert(bs->job == job);
     job->cb(job->opaque, ret);
     bs->job = NULL;
+    bdrv_op_unblock_all(bs, job->blocker);
+    error_free(job->blocker);
     g_free(job);
-    bdrv_set_in_use(bs, 0);
 }
 
 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 1e57f3a..3fb7f82 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -69,6 +69,9 @@  struct VirtIOBlockDataPlane {
                                              queue */
 
     unsigned int num_reqs;
+
+    /* Operation blocker on BDS */
+    Error *blocker;
 };
 
 /* Raise an interrupt to signal guest, if necessary */
@@ -386,6 +389,7 @@  void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
 {
     VirtIOBlockDataPlane *s;
     int fd;
+    Error *local_err = NULL;
 
     *dataplane = NULL;
 
@@ -408,9 +412,10 @@  void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
     /* If dataplane is (re-)enabled while the guest is running there could be
      * block jobs that can conflict.
      */
-    if (bdrv_in_use(blk->conf.bs)) {
-        error_setg(errp,
-                   "cannot start dataplane thread while device is in use");
+    if (bdrv_op_is_blocked(blk->conf.bs, BLOCK_OP_TYPE_DATAPLANE, &local_err)) {
+        error_report("cannot start dataplane thread: %s",
+                      error_get_pretty(local_err));
+        error_free(local_err);
         return;
     }
 
@@ -425,9 +430,8 @@  void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
     s->vdev = vdev;
     s->fd = fd;
     s->blk = blk;
-
-    /* Prevent block operations that conflict with data plane thread */
-    bdrv_set_in_use(blk->conf.bs, 1);
+    error_setg(&s->blocker, "block device is in use by data plane");
+    bdrv_op_block_all(blk->conf.bs, s->blocker);
 
     *dataplane = s;
 }
@@ -439,7 +443,8 @@  void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
     }
 
     virtio_blk_data_plane_stop(s);
-    bdrv_set_in_use(s->blk->conf.bs, 0);
+    bdrv_op_unblock_all(s->blk->conf.bs, s->blocker);
+    error_free(s->blocker);
     g_free(s);
 }
 
diff --git a/include/block/block.h b/include/block/block.h
index e6073e7..5339f92 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -458,8 +458,6 @@  void bdrv_disable_copy_on_read(BlockDriverState *bs);
 
 void bdrv_ref(BlockDriverState *bs);
 void bdrv_unref(BlockDriverState *bs);
-void bdrv_set_in_use(BlockDriverState *bs, int in_use);
-int bdrv_in_use(BlockDriverState *bs);
 
 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp);
 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 458acd6..2f6556d 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -330,7 +330,6 @@  struct BlockDriverState {
     char device_name[32];
     QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
     int refcnt;
-    int in_use; /* users other than guest access, eg. block migration */
     QTAILQ_ENTRY(BlockDriverState) list;
 
     QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index d76de62..c0a7875 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -106,6 +106,9 @@  struct BlockJob {
     /** The completion function that will be called when the job completes.  */
     BlockDriverCompletionFunc *cb;
 
+    /** Block other operations when block job is running */
+    Error *blocker;
+
     /** The opaque value that is passed to the completion function.  */
     void *opaque;
 };