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AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 39CF34E92A; Fri, 7 Jun 2019 18:10:52 +0000 (UTC) Received: from [10.10.120.179] (ovpn-120-179.rdu2.redhat.com [10.10.120.179]) by smtp.corp.redhat.com (Postfix) with ESMTP id 41F161711D; Fri, 7 Jun 2019 18:10:50 +0000 (UTC) To: Vladimir Sementsov-Ogievskiy , "qemu-block@nongnu.org" , "qemu-devel@nongnu.org" References: <20190606184159.979-1-jsnow@redhat.com> <20190606184159.979-3-jsnow@redhat.com> <70a53585-bdc6-1877-01f5-1b2d1aad8de6@virtuozzo.com> From: John Snow Openpgp: preference=signencrypt Autocrypt: addr=jsnow@redhat.com; prefer-encrypt=mutual; keydata= mQINBFTKefwBEAChvwqYC6saTzawbih87LqBYq0d5A8jXYXaiFMV/EvMSDqqY4EY6whXliNO IYzhgrPEe7ZmPxbCSe4iMykjhwMh5byIHDoPGDU+FsQty2KXuoxto+ZdrP9gymAgmyqdk3aV vzzmCa3cOppcqKvA0Kqr10UeX/z4OMVV390V+DVWUvzXpda45/Sxup57pk+hyY52wxxjIqef rj8u5BN93s5uCVTus0oiVA6W+iXYzTvVDStMFVqnTxSxlpZoH5RGKvmoWV3uutByQyBPHW2U 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rCDQYyakH2tJNQgkXkeLodBKF4bHiBbuwj0E39S9wmGgg+q4OTnAO/yhQGknle7a7G5xHBwE i0HjnLoJP5jDcoMTabZTIazXmJz3pKM11HYJ5/ZsTIf3ZRJJKIvXJpbmcAPVwTZII6XxiJdh RSSX4Mvd5pL/+5WI6NTdW6DMfigTtdd85fe6PwBNVJL2ZvBfsBJZ5rxg1TOH3KLsYBqBTgW2 glQofxhkJhDEcvjLhe3Y2BlbCWKOmvM8XS9TRt0OwUs= Message-ID: Date: Fri, 7 Jun 2019 14:10:49 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <70a53585-bdc6-1877-01f5-1b2d1aad8de6@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 07 Jun 2019 18:10:52 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 2/5] block/dirty-bitmap: Refactor bdrv_can_store_new_bitmap X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Kevin Wolf , Markus Armbruster , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 6/7/19 10:29 AM, Vladimir Sementsov-Ogievskiy wrote: > 06.06.2019 21:41, John Snow wrote: >> Instead of bdrv_can_store_new_bitmap, rework this as >> bdrv_add_persistent_dirty_bitmap. This makes a more obvious symmetry >> with bdrv_remove_persistent_dirty_bitmap. Most importantly, we are free >> to modify the driver state because we know we ARE adding a bitmap >> instead of simply being asked if we CAN store one. >> >> As part of this symmetry, move this function next to >> bdrv_remove_persistent_bitmap in block/dirty-bitmap.c. >> >> To cement this semantic distinction, use a bitmap object instead of the >> (name, granularity) pair as this allows us to set persistence as a >> condition of the "add" succeeding. >> >> Notably, the qcow2 implementation still does not actually store the new >> bitmap at add time, but merely ensures that it will be able to at store >> time. >> >> Signed-off-by: John Snow >> --- >> block/qcow2.h | 5 ++--- >> include/block/block.h | 2 -- >> include/block/block_int.h | 5 ++--- >> include/block/dirty-bitmap.h | 3 +++ >> block.c | 22 --------------------- >> block/dirty-bitmap.c | 38 ++++++++++++++++++++++++++++++++++++ >> block/qcow2-bitmap.c | 24 ++++++++++++++--------- >> block/qcow2.c | 2 +- >> blockdev.c | 19 +++++++----------- >> 9 files changed, 68 insertions(+), 52 deletions(-) >> >> diff --git a/block/qcow2.h b/block/qcow2.h >> index fc1b0d3c1e..95d723d3c0 100644 >> --- a/block/qcow2.h >> +++ b/block/qcow2.h >> @@ -742,9 +742,8 @@ 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, >> +int qcow2_add_persistent_dirty_bitmap(BlockDriverState *bs, >> + BdrvDirtyBitmap *bitmap, >> Error **errp); >> void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs, >> const char *name, >> diff --git a/include/block/block.h b/include/block/block.h >> index f9415ed740..6d520f3b59 100644 >> --- a/include/block/block.h >> +++ b/include/block/block.h >> @@ -683,8 +683,6 @@ void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child, >> Error **errp); >> void bdrv_del_child(BlockDriverState *parent, BdrvChild *child, Error **errp); >> >> -bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name, >> - uint32_t granularity, Error **errp); >> /** >> * >> * bdrv_register_buf/bdrv_unregister_buf: >> diff --git a/include/block/block_int.h b/include/block/block_int.h >> index 06df2bda1b..93bbb66cd0 100644 >> --- a/include/block/block_int.h >> +++ b/include/block/block_int.h >> @@ -537,9 +537,8 @@ 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, >> + int (*bdrv_add_persistent_dirty_bitmap)(BlockDriverState *bs, >> + BdrvDirtyBitmap *bitmap, >> Error **errp); >> void (*bdrv_remove_persistent_dirty_bitmap)(BlockDriverState *bs, >> const char *name, >> diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h >> index 8044ace63e..c37edbe05f 100644 >> --- a/include/block/dirty-bitmap.h >> +++ b/include/block/dirty-bitmap.h >> @@ -38,6 +38,9 @@ int bdrv_dirty_bitmap_check(const BdrvDirtyBitmap *bitmap, uint32_t flags, >> Error **errp); >> void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap); >> void bdrv_release_named_dirty_bitmaps(BlockDriverState *bs); >> +int bdrv_add_persistent_dirty_bitmap(BlockDriverState *bs, >> + BdrvDirtyBitmap *bitmap, >> + Error **errp); >> void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs, >> const char *name, >> Error **errp); >> diff --git a/block.c b/block.c >> index e3e77feee0..6aec36b7c9 100644 >> --- a/block.c >> +++ b/block.c >> @@ -6379,25 +6379,3 @@ void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) >> >> parent_bs->drv->bdrv_del_child(parent_bs, child, errp); >> } >> - >> -bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name, >> - uint32_t granularity, Error **errp) >> -{ >> - BlockDriver *drv = bs->drv; >> - >> - if (!drv) { >> - error_setg_errno(errp, ENOMEDIUM, >> - "Can't store persistent bitmaps to %s", >> - bdrv_get_device_or_node_name(bs)); >> - return false; >> - } >> - >> - if (!drv->bdrv_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); >> -} >> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c >> index 49646a30e6..615f8480b2 100644 >> --- a/block/dirty-bitmap.c >> +++ b/block/dirty-bitmap.c >> @@ -466,6 +466,44 @@ void bdrv_remove_persistent_dirty_bitmap(BlockDriverState *bs, >> } >> } >> >> +int bdrv_add_persistent_dirty_bitmap(BlockDriverState *bs, >> + BdrvDirtyBitmap *bitmap, >> + Error **errp) > > strange thing for me: "bitmap" in function name is _not_ the same > thing as @bitmap argument.. as if it the same, > function adds "persistent bitmap", but @bitmap is not persistent yet, > so may be function, don't add persistent bitmap, but marks bitmap persistent? > > > Ok, I can think of it like "add persistent dirty bitmap to driver. if succeed, set > bitmap.persistent flag" > Yeah, I meant "Add bitmap to file", where the persistence is implied because it's part of the file. The bitmap is indeed not YET persistent, but becomes so as a condition of this call succeeding. Do you have a suggestion for a better name? I liked the symmetry with 'remove' so that there was an obvious "add bitmap" and "remove bitmap". Of course, when you remove, it is indeed persistent, so "remove_persistent_dirty_bitmap" makes sense there. > >> +{ >> + BlockDriver *drv = bs->drv; >> + int ret; >> + >> + if (bdrv_dirty_bitmap_get_persistence(bitmap)) { >> + error_setg(errp, "Bitmap '%s' is already persistent, " >> + "and cannot be re-added to node '%s'", >> + bdrv_dirty_bitmap_name(bitmap), >> + bdrv_get_device_or_node_name(bs)); >> + return -EINVAL; >> + } >> + >> + if (!drv) { >> + error_setg_errno(errp, ENOMEDIUM, >> + "Can't store persistent bitmaps to %s", >> + bdrv_get_device_or_node_name(bs)); >> + return -ENOMEDIUM; >> + } >> + >> + if (!drv->bdrv_add_persistent_dirty_bitmap) { >> + error_setg_errno(errp, ENOTSUP, >> + "Can't store persistent bitmaps to %s", >> + bdrv_get_device_or_node_name(bs)); >> + return -ENOTSUP; >> + } >> + >> + ret = drv->bdrv_add_persistent_dirty_bitmap(bs, bitmap, errp); >> + if (ret == 0) { >> + bdrv_dirty_bitmap_set_persistence(bitmap, true); >> + } >> + >> + return ret; >> +} >> + >> + >> void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap) >> { >> bdrv_dirty_bitmap_lock(bitmap); >> diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c >> index 83aee1a42a..c3a72ca782 100644 >> --- a/block/qcow2-bitmap.c >> +++ b/block/qcow2-bitmap.c >> @@ -1607,14 +1607,16 @@ 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, >> +int qcow2_add_persistent_dirty_bitmap(BlockDriverState *bs, >> + BdrvDirtyBitmap *bitmap, >> Error **errp) >> { >> BDRVQcow2State *s = bs->opaque; >> bool found; >> Qcow2BitmapList *bm_list; >> + const char *name = bdrv_dirty_bitmap_name(bitmap); >> + uint32_t granularity = bdrv_dirty_bitmap_granularity(bitmap); >> + int ret = 0; > > dead assignment > Will take care of. >> >> if (s->qcow_version < 3) { >> /* Without autoclear_features, we would always have to assume >> @@ -1623,20 +1625,23 @@ bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs, >> * have to drop all dirty bitmaps (defeating their purpose). >> */ >> error_setg(errp, "Cannot store dirty bitmaps in qcow2 v2 files"); >> + ret = -ENOTSUP; >> goto fail; >> } >> >> - if (check_constraints_on_bitmap(bs, name, granularity, errp) != 0) { >> + ret = check_constraints_on_bitmap(bs, name, granularity, errp); >> + if (ret) { > > hmm, in other places you prefere > if ((ret = ...)) { > syntax > I have to get rid of those anyway, they violate our coding style. I'll be replacing them all with this full style. >> goto fail; >> } >> >> if (s->nb_bitmaps == 0) { >> - return true; >> + return 0; >> } >> >> if (s->nb_bitmaps >= QCOW2_MAX_BITMAPS) { >> error_setg(errp, >> "Maximum number of persistent bitmaps is already reached"); >> + ret = -EOVERFLOW; >> goto fail; >> } >> >> @@ -1644,24 +1649,25 @@ bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs, >> QCOW2_MAX_BITMAP_DIRECTORY_SIZE) >> { >> error_setg(errp, "Not enough space in the bitmap directory"); >> + ret = -EOVERFLOW; >> goto fail; >> } >> >> - if (bitmap_list_load(bs, &bm_list, errp)) { >> + if ((ret = bitmap_list_load(bs, &bm_list, errp))) { > > interesting, now we load all bitmaps, so, may be, we don't need to load list every time, > but may use bs.dirty_bitmaps to check such things.. But it seems unsafe > Yeah, I would like to cache this list eventually, but I ran into a lot of hassle with it last time I tried and put it off for now. I think we should definitely be able to. And in fact, if we did, we could even add these bitmaps to the bm_list as soon as _add_ is called and drop the need for the queued counters. >> goto fail; >> } >> >> found = find_bitmap_by_name(bm_list, name); >> bitmap_list_free(bm_list); >> if (found) { >> + ret = -EEXIST; >> error_setg(errp, "Bitmap with the same name is already stored"); >> goto fail; >> } >> >> - return true; >> - >> + return 0; >> fail: >> error_prepend(errp, "Can't make bitmap '%s' persistent in '%s': ", >> name, bdrv_get_device_or_node_name(bs)); > > didn't you consider to move this error_prepend to caller and drop all these gotos? > Nope! But I'll do that. >> - return false; >> + return ret; >> } >> diff --git a/block/qcow2.c b/block/qcow2.c >> index 9396d490d5..1c78eba71b 100644 >> --- a/block/qcow2.c >> +++ b/block/qcow2.c >> @@ -5229,7 +5229,7 @@ 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_add_persistent_dirty_bitmap = qcow2_add_persistent_dirty_bitmap, >> .bdrv_remove_persistent_dirty_bitmap = qcow2_remove_persistent_dirty_bitmap, >> }; >> >> diff --git a/blockdev.c b/blockdev.c >> index 3f44b891eb..169a8da831 100644 >> --- a/blockdev.c >> +++ b/blockdev.c >> @@ -2851,26 +2851,21 @@ void qmp_block_dirty_bitmap_add(const char *node, const char *name, >> disabled = false; >> } >> >> - if (persistent) { >> - aio_context = bdrv_get_aio_context(bs); >> - aio_context_acquire(aio_context); >> - if (!bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp)) { >> - goto out; >> - } >> - } >> - >> bitmap = bdrv_create_dirty_bitmap(bs, granularity, name, errp); >> if (bitmap == NULL) { >> - goto out; >> + return; >> } >> >> if (disabled) { >> bdrv_disable_dirty_bitmap(bitmap); >> } >> >> - bdrv_dirty_bitmap_set_persistence(bitmap, persistent); >> - out: >> - if (aio_context) { >> + if (persistent) { > > Good thing. I suggest to define aio_context in this block too. > Oh, sure. >> + aio_context = bdrv_get_aio_context(bs); >> + aio_context_acquire(aio_context); >> + if (bdrv_add_persistent_dirty_bitmap(bs, bitmap, errp)) { >> + bdrv_release_dirty_bitmap(bs, bitmap); >> + } >> aio_context_release(aio_context); >> } >> } >> > > With some my suggestions or without: > Reviewed-by: Vladimir Sementsov-Ogievskiy > I will respin anyway, so I will take your suggestions. --js