[Qemu-devel] [PATCH v3 2/9] block: add BlockJob interface for long-running operations

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 block_int.h |   83 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 83 insertions(+), 0 deletions(-)

diff --git a/block_int.h b/block_int.h
index 89a860c..bc397c4 100644
--- a/block_int.h
+++ b/block_int.h
@@ -69,6 +69,36 @@ typedef struct BlockIOBaseValue {
     uint64_t ios[2];
 } BlockIOBaseValue;
 
+typedef void BlockJobCancelFunc(void *opaque);
+typedef struct BlockJob BlockJob;
+typedef struct BlockJobType {
+    /** Derived BlockJob struct size */
+    size_t instance_size;
+
+    /** String describing the operation, part of query-block-jobs QMP API */
+    const char *job_type;
+
+    /** Optional callback for job types that support setting a speed limit */
+    int (*set_speed)(BlockJob *job, int64_t value);
+} BlockJobType;
+
+/**
+ * Long-running operation on a BlockDriverState
+ */
+struct BlockJob {
+    const BlockJobType *job_type;
+    BlockDriverState *bs;
+    bool cancelled;
+
+    /* These fields are published by the query-block-jobs QMP API */
+    int64_t offset;
+    int64_t len;
+    int64_t speed;
+
+    BlockDriverCompletionFunc *cb;
+    void *opaque;
+};
+
 struct BlockDriver {
     const char *format_name;
     int instance_size;
@@ -270,6 +300,9 @@ struct BlockDriverState {
     void *private;
 
     QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
+
+    /* long-running background operation */
+    BlockJob *job;
 };
 
 struct BlockDriverAIOCB {
@@ -293,4 +326,54 @@ void bdrv_set_io_limits(BlockDriverState *bs,
 int is_windows_drive(const char *filename);
 #endif
 
+static inline void *block_job_create(const BlockJobType *job_type,
+                                     BlockDriverState *bs,
+                                     BlockDriverCompletionFunc *cb,
+                                     void *opaque)
+{
+    BlockJob *job;
+
+    if (bdrv_in_use(bs)) {
+        return NULL;
+    }
+    bdrv_set_in_use(bs, 1);
+
+    job = g_malloc0(job_type->instance_size);
+    job->job_type      = job_type;
+    job->bs            = bs;
+    job->cb            = cb;
+    job->opaque        = opaque;
+    bs->job = job;
+    return job;
+}
+
+static inline void block_job_complete(BlockJob *job, int ret)
+{
+    BlockDriverState *bs = job->bs;
+
+    assert(bs->job == job);
+    job->cb(job->opaque, ret);
+    bs->job = NULL;
+    g_free(job);
+    bdrv_set_in_use(bs, 0);
+}
+
+static inline int block_job_set_speed(BlockJob *job, int64_t value)
+{
+    if (!job->job_type->set_speed) {
+        return -ENOTSUP;
+    }
+    return job->job_type->set_speed(job, value);
+}
+
+static inline void block_job_cancel(BlockJob *job)
+{
+    job->cancelled = true;
+}
+
+static inline bool block_job_is_cancelled(BlockJob *job)
+{
+    return job->cancelled;
+}
+
 #endif /* BLOCK_INT_H */
-- 
1.7.7.3