[Qemu-devel] [PATCH v2 13/21] block: Introduce bs->explicit_options

[Kevin Wolf <kwolf@redhat.com>]

bs->options doesn't only contain options that the user explicitly
requested, but also option that were derived from flags, the filename or
inherited from the parent node.

For reopen, it is important to know the difference because reopening the
parent can change inherited values in child nodes, but it shouldn't
change any options that were explicitly specified for the child.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c                   | 24 ++++++++++++++++++++++--
 include/block/block.h     |  1 +
 include/block/block_int.h |  1 +
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index 6dbff92..e718fd8 100644
--- a/block.c
+++ b/block.c
@@ -1495,12 +1495,15 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
         options = qdict_new();
     }
 
+    /* json: syntax counts as explicit options, as if in the QDict */
     parse_json_protocol(options, &filename, &local_err);
     if (local_err) {
         ret = -EINVAL;
         goto fail;
     }
 
+    bs->explicit_options = qdict_clone_shallow(options);
+
     if (child_role) {
         bs->inherits_from = parent;
         child_role->inherit_options(&flags, options,
@@ -1655,6 +1658,7 @@ fail:
     if (file != NULL) {
         bdrv_unref_child(bs, file);
     }
+    QDECREF(bs->explicit_options);
     QDECREF(bs->options);
     QDECREF(options);
     bs->options = NULL;
@@ -1729,7 +1733,7 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
 
     BlockReopenQueueEntry *bs_entry;
     BdrvChild *child;
-    QDict *old_options;
+    QDict *old_options, *explicit_options;
 
     if (bs_queue == NULL) {
         bs_queue = g_new0(BlockReopenQueue, 1);
@@ -1744,11 +1748,18 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
      * Precedence of options:
      * 1. Explicitly passed in options (highest)
      * 2. TODO Set in flags (only for top level)
-     * 3. TODO Retained from explicitly set options of bs
+     * 3. Retained from explicitly set options of bs
      * 4. Inherited from parent node
      * 5. Retained from effective options of bs
      */
 
+    /* Old explicitly set values (don't overwrite by inherited value) */
+    old_options = qdict_clone_shallow(bs->explicit_options);
+    bdrv_join_options(bs, options, old_options);
+    QDECREF(old_options);
+
+    explicit_options = qdict_clone_shallow(options);
+
     /* Inherit from parent node */
     if (parent_options) {
         assert(!flags);
@@ -1787,6 +1798,7 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
 
     bs_entry->state.bs = bs;
     bs_entry->state.options = options;
+    bs_entry->state.explicit_options = explicit_options;
     bs_entry->state.flags = flags;
 
     return bs_queue;
@@ -1846,6 +1858,8 @@ cleanup:
     QSIMPLEQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
         if (ret && bs_entry->prepared) {
             bdrv_reopen_abort(&bs_entry->state);
+        } else if (ret) {
+            QDECREF(bs_entry->state.explicit_options);
         }
         QDECREF(bs_entry->state.options);
         g_free(bs_entry);
@@ -1980,6 +1994,9 @@ void bdrv_reopen_commit(BDRVReopenState *reopen_state)
     }
 
     /* set BDS specific flags now */
+    QDECREF(reopen_state->bs->explicit_options);
+
+    reopen_state->bs->explicit_options   = reopen_state->explicit_options;
     reopen_state->bs->open_flags         = reopen_state->flags;
     reopen_state->bs->enable_write_cache = !!(reopen_state->flags &
                                               BDRV_O_CACHE_WB);
@@ -2003,6 +2020,8 @@ void bdrv_reopen_abort(BDRVReopenState *reopen_state)
     if (drv->bdrv_reopen_abort) {
         drv->bdrv_reopen_abort(reopen_state);
     }
+
+    QDECREF(reopen_state->explicit_options);
 }
 
 
@@ -2061,6 +2080,7 @@ void bdrv_close(BlockDriverState *bs)
         bs->sg = 0;
         bs->zero_beyond_eof = false;
         QDECREF(bs->options);
+        QDECREF(bs->explicit_options);
         bs->options = NULL;
         QDECREF(bs->full_open_options);
         bs->full_open_options = NULL;
diff --git a/include/block/block.h b/include/block/block.h
index 6d8ce86..d9b380c 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -150,6 +150,7 @@ typedef struct BDRVReopenState {
     BlockDriverState *bs;
     int flags;
     QDict *options;
+    QDict *explicit_options;
     void *opaque;
 } BDRVReopenState;
 
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 6217f1b..da7b61d 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -459,6 +459,7 @@ struct BlockDriverState {
     QLIST_HEAD(, BdrvChild) parents;
 
     QDict *options;
+    QDict *explicit_options;
     BlockdevDetectZeroesOptions detect_zeroes;
 
     /* The error object in use for blocking operations on backing_hd */
-- 
1.8.3.1