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[Qemu-block] [PATCH 26/34] block: reopen: Document option precedence and
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PATCH 26/34] block: reopen: Document option precedence and refactor accordingly |
Date: |
Fri, 8 May 2015 19:21:58 +0200 |
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>
---
block.c | 39 +++++++++++++++++++++++++++++++++------
1 file changed, 33 insertions(+), 6 deletions(-)
diff --git a/block.c b/block.c
index 8a31d62..1e5625f 100644
--- a/block.c
+++ b/block.c
@@ -1617,9 +1617,13 @@ 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);
@@ -1636,6 +1640,22 @@ 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);
qdict_join(options, old_options, false);
QDECREF(old_options);
@@ -1646,7 +1666,6 @@ 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)
@@ -1659,8 +1678,8 @@ 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);
@@ -1673,6 +1692,14 @@ 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] [PATCH 21/34] block: Consider all block layer options in append_open_options, (continued)
- [Qemu-block] [PATCH 21/34] block: Consider all block layer options in append_open_options, Kevin Wolf, 2015/05/08
- [Qemu-block] [PATCH 22/34] block: Exclude nested options only for children in append_open_options(), Kevin Wolf, 2015/05/08
- [Qemu-block] [PATCH 23/34] block: Pass driver-specific options to .bdrv_refresh_filename(), Kevin Wolf, 2015/05/08
- [Qemu-block] [PATCH 25/34] block: Allow specifying child options in reopen, Kevin Wolf, 2015/05/08
- [Qemu-block] [PATCH 26/34] block: reopen: Document option precedence and refactor accordingly,
Kevin Wolf <=
- [Qemu-block] [PATCH 24/34] block: Keep "driver" in bs->options, Kevin Wolf, 2015/05/08
- [Qemu-block] [PATCH 27/34] block: Add infrastructure for option inheritance, Kevin Wolf, 2015/05/08
- [Qemu-block] [PATCH 28/34] block: Introduce bs->explicit_options, Kevin Wolf, 2015/05/08
- [Qemu-block] [PATCH 29/34] qemu-iotests: Remove cache mode test without medium, Kevin Wolf, 2015/05/08