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>

14 files changed, 48 insertions, 20 deletions

diff --git a/block/backup.c b/block/backup.c
index 00f4f8af53..715e1d3be8 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -627,7 +627,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
     }
 
     /* The target must match the source in size, so no resize here either */
-    job->target = blk_new(BLK_PERM_WRITE,
+    job->target = blk_new(job->common.job.aio_context,
+                          BLK_PERM_WRITE,
                           BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE |
                           BLK_PERM_WRITE_UNCHANGED | BLK_PERM_GRAPH_MOD);
     ret = blk_insert_bs(job->target, target, errp);
diff --git a/block/block-backend.c b/block/block-backend.c
index 390fde6f71..f03f14acb0 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -42,6 +42,7 @@ struct BlockBackend {
     char *name;
     int refcnt;
     BdrvChild *root;
+    AioContext *ctx;
     DriveInfo *legacy_dinfo;    /* null unless created by drive_new() */
     QTAILQ_ENTRY(BlockBackend) link;         /* for block_backends */
     QTAILQ_ENTRY(BlockBackend) monitor_link; /* for monitor_block_backends */
@@ -322,12 +323,13 @@ static const BdrvChildRole child_root = {
  *
  * Return the new BlockBackend on success, null on failure.
  */
-BlockBackend *blk_new(uint64_t perm, uint64_t shared_perm)
+BlockBackend *blk_new(AioContext *ctx, uint64_t perm, uint64_t shared_perm)
 {
     BlockBackend *blk;
 
     blk = g_new0(BlockBackend, 1);
     blk->refcnt = 1;
+    blk->ctx = ctx;
     blk->perm = perm;
     blk->shared_perm = shared_perm;
     blk_set_enable_write_cache(blk, true);
@@ -347,6 +349,7 @@ BlockBackend *blk_new(uint64_t perm, uint64_t shared_perm)
 
 /*
  * Creates a new BlockBackend, opens a new BlockDriverState, and connects both.
+ * The new BlockBackend is in the main AioContext.
  *
  * Just as with bdrv_open(), after having called this function the reference to
  * @options belongs to the block layer (even on failure).
@@ -382,7 +385,7 @@ BlockBackend *blk_new_open(const char *filename, const char *reference,
         perm |= BLK_PERM_RESIZE;
     }
 
-    blk = blk_new(perm, BLK_PERM_ALL);
+    blk = blk_new(qemu_get_aio_context(), perm, BLK_PERM_ALL);
     bs = bdrv_open(filename, reference, options, flags, errp);
     if (!bs) {
         blk_unref(blk);
@@ -1856,7 +1859,15 @@ void blk_op_unblock_all(BlockBackend *blk, Error *reason)
 
 AioContext *blk_get_aio_context(BlockBackend *blk)
 {
-    return bdrv_get_aio_context(blk_bs(blk));
+    BlockDriverState *bs = blk_bs(blk);
+
+    /* FIXME The AioContext of bs and blk can be inconsistent. For the moment,
+     * we prefer the one of bs for compatibility. */
+    if (bs) {
+        return bdrv_get_aio_context(blk_bs(blk));
+    }
+
+    return blk->ctx;
 }
 
 static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb)
@@ -1888,6 +1899,7 @@ static int blk_do_set_aio_context(BlockBackend *blk, AioContext *new_context,
         }
     }
 
+    blk->ctx = new_context;
     return 0;
 }
 
diff --git a/block/commit.c b/block/commit.c
index 14e5bb394c..4d519506d6 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -338,7 +338,8 @@ void commit_start(const char *job_id, BlockDriverState *bs,
         goto fail;
     }
 
-    s->base = blk_new(BLK_PERM_CONSISTENT_READ
+    s->base = blk_new(s->common.job.aio_context,
+                      BLK_PERM_CONSISTENT_READ
                       | BLK_PERM_WRITE
                       | BLK_PERM_RESIZE,
                       BLK_PERM_CONSISTENT_READ
@@ -351,7 +352,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
     s->base_bs = base;
 
     /* Required permissions are already taken with block_job_add_bdrv() */
-    s->top = blk_new(0, BLK_PERM_ALL);
+    s->top = blk_new(s->common.job.aio_context, 0, BLK_PERM_ALL);
     ret = blk_insert_bs(s->top, top, errp);
     if (ret < 0) {
         goto fail;
@@ -395,6 +396,7 @@ int bdrv_commit(BlockDriverState *bs)
     BlockDriverState *backing_file_bs = NULL;
     BlockDriverState *commit_top_bs = NULL;
     BlockDriver *drv = bs->drv;
+    AioContext *ctx;
     int64_t offset, length, backing_length;
     int ro;
     int64_t n;
@@ -422,8 +424,9 @@ int bdrv_commit(BlockDriverState *bs)
         }
     }
 
-    src = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
-    backing = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    ctx = bdrv_get_aio_context(bs);
+    src = blk_new(ctx, BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
+    backing = blk_new(ctx, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
 
     ret = blk_insert_bs(src, bs, &local_err);
     if (ret < 0) {
diff --git a/block/crypto.c b/block/crypto.c
index 3af46b805f..7351fd479d 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -257,7 +257,8 @@ static int block_crypto_co_create_generic(BlockDriverState *bs,
     QCryptoBlock *crypto = NULL;
     struct BlockCryptoCreateData data;
 
-    blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
 
     ret = blk_insert_bs(blk, bs, errp);
     if (ret < 0) {
diff --git a/block/mirror.c b/block/mirror.c
index ec4bd9f404..eb96b52de9 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1584,7 +1584,8 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
      * We can allow anything except resize there.*/
     target_is_backing = bdrv_chain_contains(bs, target);
     target_graph_mod = (backing_mode != MIRROR_LEAVE_BACKING_CHAIN);
-    s->target = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE |
+    s->target = blk_new(s->common.job.aio_context,
+                        BLK_PERM_WRITE | BLK_PERM_RESIZE |
                         (target_graph_mod ? BLK_PERM_GRAPH_MOD : 0),
                         BLK_PERM_WRITE_UNCHANGED |
                         (target_is_backing ? BLK_PERM_CONSISTENT_READ |
diff --git a/block/parallels.c b/block/parallels.c
index 2747400577..00fae125d1 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -554,7 +554,8 @@ static int coroutine_fn parallels_co_create(BlockdevCreateOptions* opts,
         return -EIO;
     }
 
-    blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
     ret = blk_insert_bs(blk, bs, errp);
     if (ret < 0) {
         goto out;
diff --git a/block/qcow.c b/block/qcow.c
index 1bb8fd05e2..6dee5bb792 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -844,7 +844,8 @@ static int coroutine_fn qcow_co_create(BlockdevCreateOptions *opts,
         return -EIO;
     }
 
-    qcow_blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    qcow_blk = blk_new(bdrv_get_aio_context(bs),
+                       BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
     ret = blk_insert_bs(qcow_blk, bs, errp);
     if (ret < 0) {
         goto exit;
diff --git a/block/qcow2.c b/block/qcow2.c
index 14f914117f..9396d490d5 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3174,7 +3174,8 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
     }
 
     /* Create BlockBackend to write to the image */
-    blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
     ret = blk_insert_bs(blk, bs, errp);
     if (ret < 0) {
         goto out;
@@ -5006,7 +5007,8 @@ static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
     }
 
     if (new_size) {
-        BlockBackend *blk = blk_new(BLK_PERM_RESIZE, BLK_PERM_ALL);
+        BlockBackend *blk = blk_new(bdrv_get_aio_context(bs),
+                                    BLK_PERM_RESIZE, BLK_PERM_ALL);
         ret = blk_insert_bs(blk, bs, errp);
         if (ret < 0) {
             blk_unref(blk);
diff --git a/block/qed.c b/block/qed.c
index dcdcd62b4a..bb4f5c9863 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -649,7 +649,8 @@ static int coroutine_fn bdrv_qed_co_create(BlockdevCreateOptions *opts,
         return -EIO;
     }
 
-    blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
     ret = blk_insert_bs(blk, bs, errp);
     if (ret < 0) {
         goto out;
diff --git a/block/sheepdog.c b/block/sheepdog.c
index cbdfe9ab6e..f76d6ddbbc 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -1800,7 +1800,8 @@ static int sd_prealloc(BlockDriverState *bs, int64_t old_size, int64_t new_size,
     void *buf = NULL;
     int ret;
 
-    blk = blk_new(BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE | BLK_PERM_RESIZE,
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE | BLK_PERM_RESIZE,
                   BLK_PERM_ALL);
 
     ret = blk_insert_bs(blk, bs, errp);
diff --git a/block/vdi.c b/block/vdi.c
index d7ef6628e7..b9845a4cbd 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -803,7 +803,8 @@ static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
         goto exit;
     }
 
-    blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    blk = blk_new(bdrv_get_aio_context(bs_file),
+                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
     ret = blk_insert_bs(blk, bs_file, errp);
     if (ret < 0) {
         goto exit;
diff --git a/block/vhdx.c b/block/vhdx.c
index a143a57657..d6070b6fa8 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1900,7 +1900,8 @@ static int coroutine_fn vhdx_co_create(BlockdevCreateOptions *opts,
         return -EIO;
     }
 
-    blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
     ret = blk_insert_bs(blk, bs, errp);
     if (ret < 0) {
         goto delete_and_exit;
diff --git a/block/vmdk.c b/block/vmdk.c
index de8cb859f8..51067c774f 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -2356,7 +2356,8 @@ static BlockBackend *vmdk_co_create_cb(int64_t size, int idx,
     if (!bs) {
         return NULL;
     }
-    blk = blk_new(BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE | BLK_PERM_RESIZE,
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE | BLK_PERM_RESIZE,
                   BLK_PERM_ALL);
     if (blk_insert_bs(blk, bs, errp)) {
         bdrv_unref(bs);
diff --git a/block/vpc.c b/block/vpc.c
index 0c279b87c8..d4776ee8a5 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -1011,7 +1011,8 @@ static int coroutine_fn vpc_co_create(BlockdevCreateOptions *opts,
         return -EIO;
     }
 
-    blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
+    blk = blk_new(bdrv_get_aio_context(bs),
+                  BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
     ret = blk_insert_bs(blk, bs, errp);
     if (ret < 0) {
         goto out;