block: introduce dirty_bitmap_mutex

It protects only the list of dirty bitmaps; in the next patch we will
also protect their content.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-15-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>

1 files changed, 7 insertions, 37 deletions

diff --git a/blockdev.c b/blockdev.c
index ceea976b03..39f289ba68 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1362,12 +1362,10 @@ out_aio_context:
 static BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *node,
                                                   const char *name,
                                                   BlockDriverState **pbs,
-                                                  AioContext **paio,
                                                   Error **errp)
 {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
-    AioContext *aio_context;
 
     if (!node) {
         error_setg(errp, "Node cannot be NULL");
@@ -1383,29 +1381,17 @@ static BdrvDirtyBitmap *block_dirty_bitmap_lookup(const char *node,
         return NULL;
     }
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
     bitmap = bdrv_find_dirty_bitmap(bs, name);
     if (!bitmap) {
         error_setg(errp, "Dirty bitmap '%s' not found", name);
-        goto fail;
+        return NULL;
     }
 
     if (pbs) {
         *pbs = bs;
     }
-    if (paio) {
-        *paio = aio_context;
-    } else {
-        aio_context_release(aio_context);
-    }
 
     return bitmap;
-
- fail:
-    aio_context_release(aio_context);
-    return NULL;
 }
 
 /* New and old BlockDriverState structs for atomic group operations */
@@ -2025,7 +2011,6 @@ static void block_dirty_bitmap_clear_prepare(BlkActionState *common,
     state->bitmap = block_dirty_bitmap_lookup(action->node,
                                               action->name,
                                               &state->bs,
-                                              &state->aio_context,
                                               errp);
     if (!state->bitmap) {
         return;
@@ -2733,7 +2718,6 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
                                 bool has_granularity, uint32_t granularity,
                                 Error **errp)
 {
-    AioContext *aio_context;
     BlockDriverState *bs;
 
     if (!name || name[0] == '\0') {
@@ -2746,14 +2730,11 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
         return;
     }
 
-    aio_context = bdrv_get_aio_context(bs);
-    aio_context_acquire(aio_context);
-
     if (has_granularity) {
         if (granularity < 512 || !is_power_of_2(granularity)) {
             error_setg(errp, "Granularity must be power of 2 "
                              "and at least 512");
-            goto out;
+            return;
         }
     } else {
         /* Default to cluster size, if available: */
@@ -2761,19 +2742,15 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name,
     }
 
     bdrv_create_dirty_bitmap(bs, granularity, name, errp);
-
- out:
-    aio_context_release(aio_context);
 }
 
 void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
                                    Error **errp)
 {
-    AioContext *aio_context;
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
 
-    bitmap = block_dirty_bitmap_lookup(node, name, &bs, &aio_context, errp);
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
     if (!bitmap || !bs) {
         return;
     }
@@ -2782,13 +2759,10 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
         error_setg(errp,
                    "Bitmap '%s' is currently frozen and cannot be removed",
                    name);
-        goto out;
+        return;
     }
     bdrv_dirty_bitmap_make_anon(bitmap);
     bdrv_release_dirty_bitmap(bs, bitmap);
-
- out:
-    aio_context_release(aio_context);
 }
 
 /**
@@ -2798,11 +2772,10 @@ void qmp_block_dirty_bitmap_remove(const char *node, const char *name,
 void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
                                   Error **errp)
 {
-    AioContext *aio_context;
     BdrvDirtyBitmap *bitmap;
     BlockDriverState *bs;
 
-    bitmap = block_dirty_bitmap_lookup(node, name, &bs, &aio_context, errp);
+    bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
     if (!bitmap || !bs) {
         return;
     }
@@ -2811,18 +2784,15 @@ void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
         error_setg(errp,
                    "Bitmap '%s' is currently frozen and cannot be modified",
                    name);
-        goto out;
+        return;
     } else if (!bdrv_dirty_bitmap_enabled(bitmap)) {
         error_setg(errp,
                    "Bitmap '%s' is currently disabled and cannot be cleared",
                    name);
-        goto out;
+        return;
     }
 
     bdrv_clear_dirty_bitmap(bitmap, NULL);
-
- out:
-    aio_context_release(aio_context);
 }
 
 void hmp_drive_del(Monitor *mon, const QDict *qdict)