From d03654eacdf35f436fbe78ca46cea215d5165ab5 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 6 Mar 2018 20:48:18 +0000 Subject: [PATCH] block: let blk_add/remove_aio_context_notifier() tolerate BDS changes Commit 2019ba0a0197 ("block: Add AioContextNotifier functions to BB") added blk_add/remove_aio_context_notifier() and implemented them by passing through the bdrv_*() equivalent. This doesn't work across bdrv_append(), which detaches child->bs and re-attaches it to a new BlockDriverState. When blk_remove_aio_context_notifier() is called we will access the new BDS instead of the one where the notifier was added! >From the point of view of the blk_*() API user, changes to the root BDS should be transparent. This patch maintains a list of AioContext notifiers in BlockBackend and adds/removes them from the BlockDriverState as needed. Reported-by: Stefano Panella Cc: Max Reitz Signed-off-by: Stefan Hajnoczi Message-Id: <20180306204819.11266-2-stefanha@redhat.com> Reviewed-by: Max Reitz Signed-off-by: Eric Blake --- block/block-backend.c | 63 +++++++++++++++++++++++++++++++++++++++++++ block/trace-events | 2 ++ 2 files changed, 65 insertions(+) diff --git a/block/block-backend.c b/block/block-backend.c index f2e0a855ff7c..681b240b1268 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -31,6 +31,13 @@ static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb); +typedef struct BlockBackendAioNotifier { + void (*attached_aio_context)(AioContext *new_context, void *opaque); + void (*detach_aio_context)(void *opaque); + void *opaque; + QLIST_ENTRY(BlockBackendAioNotifier) list; +} BlockBackendAioNotifier; + struct BlockBackend { char *name; int refcnt; @@ -69,6 +76,7 @@ struct BlockBackend { bool allow_write_beyond_eof; NotifierList remove_bs_notifiers, insert_bs_notifiers; + QLIST_HEAD(, BlockBackendAioNotifier) aio_notifiers; int quiesce_counter; VMChangeStateEntry *vmsh; @@ -247,6 +255,36 @@ static int blk_root_inactivate(BdrvChild *child) return 0; } +static void blk_root_attach(BdrvChild *child) +{ + BlockBackend *blk = child->opaque; + BlockBackendAioNotifier *notifier; + + trace_blk_root_attach(child, blk, child->bs); + + QLIST_FOREACH(notifier, &blk->aio_notifiers, list) { + bdrv_add_aio_context_notifier(child->bs, + notifier->attached_aio_context, + notifier->detach_aio_context, + notifier->opaque); + } +} + +static void blk_root_detach(BdrvChild *child) +{ + BlockBackend *blk = child->opaque; + BlockBackendAioNotifier *notifier; + + trace_blk_root_detach(child, blk, child->bs); + + QLIST_FOREACH(notifier, &blk->aio_notifiers, list) { + bdrv_remove_aio_context_notifier(child->bs, + notifier->attached_aio_context, + notifier->detach_aio_context, + notifier->opaque); + } +} + static const BdrvChildRole child_root = { .inherit_options = blk_root_inherit_options, @@ -260,6 +298,9 @@ static const BdrvChildRole child_root = { .activate = blk_root_activate, .inactivate = blk_root_inactivate, + + .attach = blk_root_attach, + .detach = blk_root_detach, }; /* @@ -287,6 +328,7 @@ BlockBackend *blk_new(uint64_t perm, uint64_t shared_perm) notifier_list_init(&blk->remove_bs_notifiers); notifier_list_init(&blk->insert_bs_notifiers); + QLIST_INIT(&blk->aio_notifiers); QTAILQ_INSERT_TAIL(&block_backends, blk, link); return blk; @@ -364,6 +406,7 @@ static void blk_delete(BlockBackend *blk) } assert(QLIST_EMPTY(&blk->remove_bs_notifiers.notifiers)); assert(QLIST_EMPTY(&blk->insert_bs_notifiers.notifiers)); + assert(QLIST_EMPTY(&blk->aio_notifiers)); QTAILQ_REMOVE(&block_backends, blk, link); drive_info_del(blk->legacy_dinfo); block_acct_cleanup(&blk->stats); @@ -1857,8 +1900,15 @@ void blk_add_aio_context_notifier(BlockBackend *blk, void (*attached_aio_context)(AioContext *new_context, void *opaque), void (*detach_aio_context)(void *opaque), void *opaque) { + BlockBackendAioNotifier *notifier; BlockDriverState *bs = blk_bs(blk); + notifier = g_new(BlockBackendAioNotifier, 1); + notifier->attached_aio_context = attached_aio_context; + notifier->detach_aio_context = detach_aio_context; + notifier->opaque = opaque; + QLIST_INSERT_HEAD(&blk->aio_notifiers, notifier, list); + if (bs) { bdrv_add_aio_context_notifier(bs, attached_aio_context, detach_aio_context, opaque); @@ -1871,12 +1921,25 @@ void blk_remove_aio_context_notifier(BlockBackend *blk, void (*detach_aio_context)(void *), void *opaque) { + BlockBackendAioNotifier *notifier; BlockDriverState *bs = blk_bs(blk); if (bs) { bdrv_remove_aio_context_notifier(bs, attached_aio_context, detach_aio_context, opaque); } + + QLIST_FOREACH(notifier, &blk->aio_notifiers, list) { + if (notifier->attached_aio_context == attached_aio_context && + notifier->detach_aio_context == detach_aio_context && + notifier->opaque == opaque) { + QLIST_REMOVE(notifier, list); + g_free(notifier); + return; + } + } + + abort(); } void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify) diff --git a/block/trace-events b/block/trace-events index 02dd80ff0c35..7493d521dcf2 100644 --- a/block/trace-events +++ b/block/trace-events @@ -7,6 +7,8 @@ bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d" # block/block-backend.c blk_co_preadv(void *blk, void *bs, int64_t offset, unsigned int bytes, int flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x" blk_co_pwritev(void *blk, void *bs, int64_t offset, unsigned int bytes, int flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x" +blk_root_attach(void *child, void *blk, void *bs) "child %p blk %p bs %p" +blk_root_detach(void *child, void *blk, void *bs) "child %p blk %p bs %p" # block/io.c bdrv_co_preadv(void *bs, int64_t offset, int64_t nbytes, unsigned int flags) "bs %p offset %"PRId64" nbytes %"PRId64" flags 0x%x"