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[Qemu-block] [PULL 13/48] block: reopen: Document option precedence and
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 13/48] block: reopen: Document option precedence and refactor accordingly |
Date: |
Fri, 18 Dec 2015 16:07:19 +0100 |
The interesting part of reopening an image is from which sources the
effective options should be taken, i.e. which options take precedence
over which other options. This patch documents the precedence that will
be implemented in the following patches.
It also refactors bdrv_reopen_queue(), so that the top-level reopened
node is handled the same way as children are. Option/flag inheritance
from the parent becomes just one item in the list and is done at the
beginning of the function, similar to how the other items are/will be
handled.
Signed-off-by: Kevin Wolf <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
---
block.c | 39 +++++++++++++++++++++++++++++++++------
1 file changed, 33 insertions(+), 6 deletions(-)
diff --git a/block.c b/block.c
index 9c42b17..5fd6c44 100644
--- a/block.c
+++ b/block.c
@@ -1693,9 +1693,13 @@ typedef struct BlockReopenQueueEntry {
* bs_queue, or the existing bs_queue being used.
*
*/
-BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
- BlockDriverState *bs,
- QDict *options, int flags)
+static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
+ BlockDriverState *bs,
+ QDict *options,
+ int flags,
+ const BdrvChildRole *role,
+ QDict *parent_options,
+ int parent_flags)
{
assert(bs != NULL);
@@ -1712,6 +1716,22 @@ BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue
*bs_queue,
options = qdict_new();
}
+ /*
+ * 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
+ * 4. TODO Inherited from parent node
+ * 5. Retained from effective options of bs
+ */
+
+ /* Inherit from parent node */
+ if (parent_options) {
+ assert(!flags);
+ flags = role->inherit_flags(parent_flags);
+ }
+
+ /* Old values are used for options that aren't set yet */
old_options = qdict_clone_shallow(bs->options);
bdrv_join_options(bs, options, old_options);
QDECREF(old_options);
@@ -1722,7 +1742,6 @@ BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue
*bs_queue,
QLIST_FOREACH(child, &bs->children, next) {
QDict *new_child_options;
char *child_key_dot;
- int child_flags;
/* reopen can only change the options of block devices that were
* implicitly created and inherited options. For other (referenced)
@@ -1735,8 +1754,8 @@ BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue
*bs_queue,
qdict_extract_subqdict(options, &new_child_options, child_key_dot);
g_free(child_key_dot);
- child_flags = child->role->inherit_flags(flags);
- bdrv_reopen_queue(bs_queue, child->bs, new_child_options, child_flags);
+ bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options, 0,
+ child->role, options, flags);
}
bs_entry = g_new0(BlockReopenQueueEntry, 1);
@@ -1749,6 +1768,14 @@ BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue
*bs_queue,
return bs_queue;
}
+BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
+ BlockDriverState *bs,
+ QDict *options, int flags)
+{
+ return bdrv_reopen_queue_child(bs_queue, bs, options, flags,
+ NULL, NULL, 0);
+}
+
/*
* Reopen multiple BlockDriverStates atomically & transactionally.
*
--
1.8.3.1
- [Qemu-block] [PULL 06/48] mirror: Error out when a BDS would get two BBs, (continued)
- [Qemu-block] [PULL 06/48] mirror: Error out when a BDS would get two BBs, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 22/48] qemu-iotests: Try setting cache mode for children, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 38/48] iotests: Update comments for bdrv_swap() in 094, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 28/48] qcow2: Use abort() instead of assert(false), Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 25/48] progress: Allow regressing progress, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 08/48] block: Consider all block layer options in append_open_options, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 48/48] block/qapi: allow best-effort query, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 27/48] qcow2: Use error_report() in qcow2_amend_options(), Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 29/48] qcow2: Split upgrade/downgrade paths for amend, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 46/48] block/qapi: explicitly warn if !has_full_backing_filename, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 13/48] block: reopen: Document option precedence and refactor accordingly,
Kevin Wolf <=
- [Qemu-block] [PULL 10/48] block: Pass driver-specific options to .bdrv_refresh_filename(), Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 47/48] qemu-img: abort when full_backing_filename not present, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 37/48] block: Remove prototype of bdrv_swap from header, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 30/48] qcow2: Use intermediate helper CB for amend, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 16/48] block: Introduce bs->explicit_options, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 26/48] block: Add opaque value to the amend CB, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 32/48] qcow2: Invoke refcount order amendment function, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 11/48] block: Keep "driver" in bs->options, Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 09/48] block: Exclude nested options only for children in append_open_options(), Kevin Wolf, 2015/12/18
- [Qemu-block] [PULL 07/48] block: Allow references for backing files, Kevin Wolf, 2015/12/18