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block: Add infrastructure for option inheritance

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Options are not actually inherited from the parent node yet, but this
commit lays the grounds for doing so.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Kevin Wolf 2015-04-29 17:29:39 +02:00
parent 2851810223
commit 8e2160e2c7
2 changed files with 33 additions and 22 deletions
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52
block.c
View File

@ -695,11 +695,14 @@ static int bdrv_temp_snapshot_flags(int flags)
}
/*
* Returns the flags that bs->file should get if a protocol driver is expected,
* based on the given flags for the parent BDS
* Returns the options and flags that bs->file should get if a protocol driver
* is expected, based on the given options and flags for the parent BDS
*/
static int bdrv_inherited_flags(int flags)
static void bdrv_inherited_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
/* Enable protocol handling, disable format probing for bs->file */
flags |= BDRV_O_PROTOCOL;
@ -710,45 +713,51 @@ static int bdrv_inherited_flags(int flags)
/* Clear flags that only apply to the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
return flags;
*child_flags = flags;
}
const BdrvChildRole child_file = {
.inherit_flags = bdrv_inherited_flags,
.inherit_options = bdrv_inherited_options,
};
/*
* Returns the flags that bs->file should get if the use of formats (and not
* only protocols) is permitted for it, based on the given flags for the parent
* BDS
* Returns the options and flags that bs->file should get if the use of formats
* (and not only protocols) is permitted for it, based on the given options and
* flags for the parent BDS
*/
static int bdrv_inherited_fmt_flags(int parent_flags)
static void bdrv_inherited_fmt_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = child_file.inherit_flags(parent_flags);
return flags & ~BDRV_O_PROTOCOL;
child_file.inherit_options(child_flags, child_options,
parent_flags, parent_options);
*child_flags &= ~BDRV_O_PROTOCOL;
}
const BdrvChildRole child_format = {
.inherit_flags = bdrv_inherited_fmt_flags,
.inherit_options = bdrv_inherited_fmt_options,
};
/*
* Returns the flags that bs->backing should get, based on the given flags
* for the parent BDS
* Returns the options and flags that bs->backing should get, based on the
* given options and flags for the parent BDS
*/
static int bdrv_backing_flags(int flags)
static void bdrv_backing_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
/* backing files always opened read-only */
flags &= ~(BDRV_O_RDWR | BDRV_O_COPY_ON_READ);
/* snapshot=on is handled on the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_TEMPORARY);
return flags;
*child_flags = flags;
}
static const BdrvChildRole child_backing = {
.inherit_flags = bdrv_backing_flags,
.inherit_options = bdrv_backing_options,
};
static int bdrv_open_flags(BlockDriverState *bs, int flags)
@ -1480,7 +1489,8 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
if (child_role) {
bs->inherits_from = parent;
flags = child_role->inherit_flags(parent->open_flags);
child_role->inherit_options(&flags, options,
parent->open_flags, parent->options);
}
ret = bdrv_fill_options(&options, &filename, &flags, &local_err);
@ -1518,7 +1528,7 @@ static int bdrv_open_inherit(BlockDriverState **pbs, const char *filename,
}
if (flags & BDRV_O_SNAPSHOT) {
snapshot_flags = bdrv_temp_snapshot_flags(flags);
flags = bdrv_backing_flags(flags);
bdrv_backing_options(&flags, options, flags, options);
}
bs->open_flags = flags;
@ -1721,14 +1731,14 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
* 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
* 4. 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);
role->inherit_options(&flags, options, parent_flags, parent_options);
}
/* Old values are used for options that aren't set yet */

3
include/block/block_int.h
View File

@ -343,7 +343,8 @@ typedef struct BdrvAioNotifier {
} BdrvAioNotifier;
struct BdrvChildRole {
int (*inherit_flags)(int parent_flags);
void (*inherit_options)(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options);
};
extern const BdrvChildRole child_file;