From 33384421b3abe74555baeaf788b17204cd8c6080 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Fri, 20 Jun 2014 21:57:33 +0200 Subject: [PATCH] block: Add AIO context notifiers 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 Reviewed-by: Stefan Hajnoczi Signed-off-by: Stefan Hajnoczi --- block.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++ include/block/block_int.h | 41 ++++++++++++++++++++++++++++++++++ 2 files changed, 97 insertions(+) diff --git a/block.c b/block.c index 1df13ac..9c5566b 100644 --- a/block.c +++ b/block.c @@ -1819,6 +1819,8 @@ void bdrv_reopen_abort(BDRVReopenState *reopen_state) void bdrv_close(BlockDriverState *bs) { + BdrvAioNotifier *ban, *ban_next; + if (bs->job) { block_job_cancel_sync(bs->job); } @@ -1863,6 +1865,11 @@ void bdrv_close(BlockDriverState *bs) if (bs->io_limits_enabled) { bdrv_io_limits_disable(bs); } + + QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { + g_free(ban); + } + QLIST_INIT(&bs->aio_notifiers); } void bdrv_close_all(void) @@ -5729,10 +5736,16 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs) void bdrv_detach_aio_context(BlockDriverState *bs) { + BdrvAioNotifier *baf; + if (!bs->drv) { return; } + QLIST_FOREACH(baf, &bs->aio_notifiers, list) { + baf->detach_aio_context(baf->opaque); + } + if (bs->io_limits_enabled) { throttle_detach_aio_context(&bs->throttle_state); } @@ -5752,6 +5765,8 @@ void bdrv_detach_aio_context(BlockDriverState *bs) void bdrv_attach_aio_context(BlockDriverState *bs, AioContext *new_context) { + BdrvAioNotifier *ban; + if (!bs->drv) { return; } @@ -5770,6 +5785,10 @@ void bdrv_attach_aio_context(BlockDriverState *bs, if (bs->io_limits_enabled) { throttle_attach_aio_context(&bs->throttle_state, new_context); } + + QLIST_FOREACH(ban, &bs->aio_notifiers, list) { + ban->attached_aio_context(new_context, ban->opaque); + } } void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) @@ -5786,6 +5805,43 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) aio_context_release(new_context); } +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) +{ + BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1); + *ban = (BdrvAioNotifier){ + .attached_aio_context = attached_aio_context, + .detach_aio_context = detach_aio_context, + .opaque = opaque + }; + + QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list); +} + +void bdrv_remove_aio_context_notifier(BlockDriverState *bs, + void (*attached_aio_context)(AioContext *, + void *), + void (*detach_aio_context)(void *), + void *opaque) +{ + BdrvAioNotifier *ban, *ban_next; + + QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { + if (ban->attached_aio_context == attached_aio_context && + ban->detach_aio_context == detach_aio_context && + ban->opaque == opaque) + { + QLIST_REMOVE(ban, list); + g_free(ban); + + return; + } + } + + abort(); +} + void bdrv_add_before_write_notifier(BlockDriverState *bs, NotifierWithReturn *notifier) { diff --git a/include/block/block_int.h b/include/block/block_int.h index 2334895..8a61215 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -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 -- 2.7.4