[libvirt] [PULL 04/19] block/qcow2: proper locking on bitmap add/remove paths

From: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com&gt; qmp_block_dirty_bitmap_add and do_block_dirty_bitmap_remove do acquire aio context since 0a6c86d024c52b. But this is not enough: we also must lock qcow2 mutex when access in-image metadata. Especially it concerns freeing qcow2 clusters. To achieve this, move qcow2_can_store_new_dirty_bitmap and qcow2_remove_persistent_dirty_bitmap to coroutine context. Since we work in coroutines in correct aio context, we don't need context acquiring in blockdev.c anymore, drop it. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com&gt; Reviewed-by: John Snow <jsnow(a)redhat.com&gt; Message-id: 20190920082543.23444-4-vsementsov(a)virtuozzo.com Signed-off-by: John Snow <jsnow(a)redhat.com&gt; --- block/qcow2.h | 11 ++-- include/block/block_int.h | 10 ++-- block/dirty-bitmap.c | 102 +++++++++++++++++++++++++++++++++++--- block/qcow2-bitmap.c | 24 ++++++--- block/qcow2.c | 5 +- blockdev.c | 27 +++------- 6 files changed, 131 insertions(+), 48 deletions(-) diff --git a/block/qcow2.h b/block/qcow2.h index 2ed54821635..113d99bf520 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -743,12 +743,13 @@ int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp); int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp); void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp); int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp); -bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs, - const char *name, - uint32_t granularity, - Error **errp); -int qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs, const char *name, +bool qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs, + const char *name, + uint32_t granularity, Error **errp); +int qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs, + const char *name, + Error **errp); ssize_t coroutine_fn qcow2_co_compress(BlockDriverState *bs, void *dest, size_t dest_size, diff --git a/include/block/block_int.h b/include/block/block_int.h index 503ac9e3cd2..1e54486ad14 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -552,13 +552,13 @@ struct BlockDriver { * field of BlockDirtyBitmap's in case of success. */ int (*bdrv_reopen_bitmaps_rw)(BlockDriverState *bs, Error **errp); - bool (*bdrv_can_store_new_dirty_bitmap)(BlockDriverState *bs, - const char *name, - uint32_t granularity, - Error **errp); - int (*bdrv_remove_persistent_dirty_bitmap)(BlockDriverState *bs, + bool (*bdrv_co_can_store_new_dirty_bitmap)(BlockDriverState *bs, const char *name, + uint32_t granularity, Error **errp); + int (*bdrv_co_remove_persistent_dirty_bitmap)(BlockDriverState *bs, + const char *name, + Error **errp); /** * Register/unregister a buffer for I/O. For example, when the driver is diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c index d1ae2e19229..03e0872b972 100644 --- a/block/dirty-bitmap.c +++ b/block/dirty-bitmap.c @@ -26,6 +26,7 @@ #include "trace.h" #include "block/block_int.h" #include "block/blockjob.h" +#include "qemu/main-loop.h" struct BdrvDirtyBitmap { QemuMutex *mutex; @@ -455,18 +456,59 @@ void bdrv_release_named_dirty_bitmaps(BlockDriverState *bs) * not fail. * This function doesn't release corresponding BdrvDirtyBitmap. */ +static int coroutine_fn +bdrv_co_remove_persistent_dirty_bitmap(BlockDriverState *bs, const char *name, + Error **errp) +{ + if (bs->drv && bs->drv->bdrv_co_remove_persistent_dirty_bitmap) { + return bs->drv->bdrv_co_remove_persistent_dirty_bitmap(bs, name, errp); + } + + return 0; +} + +typedef struct BdrvRemovePersistentDirtyBitmapCo { + BlockDriverState *bs; + const char *name; + Error **errp; + int ret; +} BdrvRemovePersistentDirtyBitmapCo; + +static void coroutine_fn +bdrv_co_remove_persistent_dirty_bitmap_entry(void *opaque) +{ + BdrvRemovePersistentDirtyBitmapCo *s = opaque; + + s->ret = bdrv_co_remove_persistent_dirty_bitmap(s->bs, s->name, s->errp); + aio_wait_kick(); +} + int bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs, const char *name, Error **errp) { - if (bs->drv && bs->drv->bdrv_remove_persistent_dirty_bitmap) { - return bs->drv->bdrv_remove_persistent_dirty_bitmap(bs, name, errp); + if (qemu_in_coroutine()) { + return bdrv_co_remove_persistent_dirty_bitmap(bs, name, errp); + } else { + Coroutine *co; + BdrvRemovePersistentDirtyBitmapCo s = { + .bs = bs, + .name = name, + .errp = errp, + .ret = -EINPROGRESS, + }; + + co = qemu_coroutine_create(bdrv_co_remove_persistent_dirty_bitmap_entry, + &s); + bdrv_coroutine_enter(bs, co); + BDRV_POLL_WHILE(bs, s.ret == -EINPROGRESS); + + return s.ret; } - - return 0; } -bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name, - uint32_t granularity, Error **errp) +static bool coroutine_fn +bdrv_co_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name, + uint32_t granularity, Error **errp) { BlockDriver *drv = bs->drv; @@ -477,14 +519,58 @@ bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name, return false; } - if (!drv->bdrv_can_store_new_dirty_bitmap) { + if (!drv->bdrv_co_can_store_new_dirty_bitmap) { error_setg_errno(errp, ENOTSUP, "Can't store persistent bitmaps to %s", bdrv_get_device_or_node_name(bs)); return false; } - return drv->bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp); + return drv->bdrv_co_can_store_new_dirty_bitmap(bs, name, granularity, errp); +} + +typedef struct BdrvCanStoreNewDirtyBitmapCo { + BlockDriverState *bs; + const char *name; + uint32_t granularity; + Error **errp; + bool ret; + + bool in_progress; +} BdrvCanStoreNewDirtyBitmapCo; + +static void coroutine_fn bdrv_co_can_store_new_dirty_bitmap_entry(void *opaque) +{ + BdrvCanStoreNewDirtyBitmapCo *s = opaque; + + s->ret = bdrv_co_can_store_new_dirty_bitmap(s->bs, s->name, s->granularity, + s->errp); + s->in_progress = false; + aio_wait_kick(); +} + +bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name, + uint32_t granularity, Error **errp) +{ + if (qemu_in_coroutine()) { + return bdrv_co_can_store_new_dirty_bitmap(bs, name, granularity, errp); + } else { + Coroutine *co; + BdrvCanStoreNewDirtyBitmapCo s = { + .bs = bs, + .name = name, + .granularity = granularity, + .errp = errp, + .in_progress = true, + }; + + co = qemu_coroutine_create(bdrv_co_can_store_new_dirty_bitmap_entry, + &s); + bdrv_coroutine_enter(bs, co); + BDRV_POLL_WHILE(bs, s.in_progress); + + return s.ret; + } } void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap) diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index 9821c1628f5..644837eb033 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -1404,12 +1404,13 @@ static Qcow2Bitmap *find_bitmap_by_name(Qcow2BitmapList *bm_list, return NULL; } -int qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs, const char *name, - Error **errp) +int coroutine_fn qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs, + const char *name, + Error **errp) { int ret; BDRVQcow2State *s = bs->opaque; - Qcow2Bitmap *bm; + Qcow2Bitmap *bm = NULL; Qcow2BitmapList *bm_list; if (s->nb_bitmaps == 0) { @@ -1418,10 +1419,13 @@ int qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs, const char *name, return 0; } + qemu_co_mutex_lock(&s->lock); + bm_list = bitmap_list_load(bs, s->bitmap_directory_offset, s->bitmap_directory_size, errp); if (bm_list == NULL) { - return -EIO; + ret = -EIO; + goto out; } bm = find_bitmap_by_name(bm_list, name); @@ -1441,6 +1445,8 @@ int qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs, const char *name, free_bitmap_clusters(bs, &bm->table); out: + qemu_co_mutex_unlock(&s->lock); + bitmap_free(bm); bitmap_list_free(bm_list); @@ -1615,10 +1621,10 @@ int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp) return 0; } -bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs, - const char *name, - uint32_t granularity, - Error **errp) +bool coroutine_fn qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs, + const char *name, + uint32_t granularity, + Error **errp) { BDRVQcow2State *s = bs->opaque; bool found; @@ -1655,8 +1661,10 @@ bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs, goto fail; } + qemu_co_mutex_lock(&s->lock); bm_list = bitmap_list_load(bs, s->bitmap_directory_offset, s->bitmap_directory_size, errp); + qemu_co_mutex_unlock(&s->lock); if (bm_list == NULL) { goto fail; } diff --git a/block/qcow2.c b/block/qcow2.c index 4d16393e618..43a6cc423de 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -5263,8 +5263,9 @@ BlockDriver bdrv_qcow2 = { .bdrv_attach_aio_context = qcow2_attach_aio_context, .bdrv_reopen_bitmaps_rw = qcow2_reopen_bitmaps_rw, - .bdrv_can_store_new_dirty_bitmap = qcow2_can_store_new_dirty_bitmap, - .bdrv_remove_persistent_dirty_bitmap = qcow2_remove_persistent_dirty_bitmap, + .bdrv_co_can_store_new_dirty_bitmap = qcow2_co_can_store_new_dirty_bitmap, + .bdrv_co_remove_persistent_dirty_bitmap = + qcow2_co_remove_persistent_dirty_bitmap, }; static void bdrv_qcow2_init(void) diff --git a/blockdev.c b/blockdev.c index 0813adfb2b1..228ce94a88c 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2898,16 +2898,10 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name, disabled = false; } - if (persistent) { - AioContext *aio_context = bdrv_get_aio_context(bs); - bool ok; - - aio_context_acquire(aio_context); - ok = bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp); - aio_context_release(aio_context); - if (!ok) { - return; - } + if (persistent && + !bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp)) + { + return; } bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp); @@ -2939,17 +2933,10 @@ static BdrvDirtyBitmap *do_block_dirty_bitmap_remove( return NULL; } - if (bdrv_dirty_bitmap_get_persistence(bitmap)) { - int ret; - AioContext *aio_context = bdrv_get_aio_context(bs); - - aio_context_acquire(aio_context); - ret = bdrv_remove_persistent_dirty_bitmap(bs, name, errp); - aio_context_release(aio_context); - - if (ret < 0) { + if (bdrv_dirty_bitmap_get_persistence(bitmap) && + bdrv_remove_persistent_dirty_bitmap(bs, name, errp) < 0) + { return NULL; - } } if (release) { -- 2.21.0