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block: Add AIO context notifiers

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If a long-running operation on a BDS wants to always remain in the same
AIO context, it somehow needs to keep track of the BDS changing its
context. This adds a function for registering callbacks on a BDS which
are called whenever the BDS is attached or detached from an AIO context.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Max Reitz 2014-06-20 21:57:33 +02:00 • committed by Stefan Hajnoczi
parent 958c717df9
commit 33384421b3
2 changed files with 97 additions and 0 deletions
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41
include/block/block_int.h
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@ -294,6 +294,15 @@ typedef struct BlockLimits {
typedef struct BdrvOpBlocker BdrvOpBlocker;
typedef struct BdrvAioNotifier {
void (*attached_aio_context)(AioContext *new_context, void *opaque);
void (*detach_aio_context)(void *opaque);
void *opaque;
QLIST_ENTRY(BdrvAioNotifier) list;
} BdrvAioNotifier;
/*
* Note: the function bdrv_append() copies and swaps contents of
* BlockDriverStates, so if you add new fields to this struct, please
@ -320,6 +329,10 @@ struct BlockDriverState {
void *dev_opaque;
AioContext *aio_context; /* event loop used for fd handlers, timers, etc */
/* long-running tasks intended to always use the same AioContext as this
* BDS may register themselves in this list to be notified of changes
* regarding this BDS's context */
QLIST_HEAD(, BdrvAioNotifier) aio_notifiers;
char filename[1024];
char backing_file[1024]; /* if non zero, the image is a diff of
@ -437,6 +450,34 @@ void bdrv_detach_aio_context(BlockDriverState *bs);
void bdrv_attach_aio_context(BlockDriverState *bs,
AioContext *new_context);
/**
* bdrv_add_aio_context_notifier:
*
* If a long-running job intends to be always run in the same AioContext as a
* certain BDS, it may use this function to be notified of changes regarding the
* association of the BDS to an AioContext.
*
* attached_aio_context() is called after the target BDS has been attached to a
* new AioContext; detach_aio_context() is called before the target BDS is being
* detached from its old AioContext.
*/
void bdrv_add_aio_context_notifier(BlockDriverState *bs,
void (*attached_aio_context)(AioContext *new_context, void *opaque),
void (*detach_aio_context)(void *opaque), void *opaque);
/**
* bdrv_remove_aio_context_notifier:
*
* Unsubscribe of change notifications regarding the BDS's AioContext. The
* parameters given here have to be the same as those given to
* bdrv_add_aio_context_notifier().
*/
void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
void (*aio_context_attached)(AioContext *,
void *),
void (*aio_context_detached)(void *),
void *opaque);
#ifdef _WIN32
int is_windows_drive(const char *filename);
#endif