From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39352) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YSuIz-0004Ky-ML for qemu-devel@nongnu.org; Tue, 03 Mar 2015 16:24:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YSuIt-0005ds-BN for qemu-devel@nongnu.org; Tue, 03 Mar 2015 16:24:41 -0500 Message-ID: <54F62690.5010809@redhat.com> Date: Tue, 03 Mar 2015 16:24:32 -0500 From: John Snow MIME-Version: 1.0 References: <1425338403-16138-1-git-send-email-jsnow@redhat.com> <1425338403-16138-15-git-send-email-jsnow@redhat.com> <54F5DB10.9010608@redhat.com> In-Reply-To: <54F5DB10.9010608@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 14/17] block: Resize bitmaps on bdrv_truncate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz , qemu-block@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, vsementsov@parallels.com, stefanha@redhat.com On 03/03/2015 11:02 AM, Max Reitz wrote: > On 2015-03-02 at 18:20, John Snow wrote: >> Signed-off-by: John Snow >> --- >> block.c | 22 ++++++++++++++++++++ >> include/block/block.h | 1 + >> include/qemu/hbitmap.h | 10 +++++++++ >> util/hbitmap.c | 55 >> ++++++++++++++++++++++++++++++++++++++++++++++++++ >> 4 files changed, 88 insertions(+) >> >> diff --git a/block.c b/block.c >> index e6b2696..5eaa874 100644 >> --- a/block.c >> +++ b/block.c >> @@ -3543,6 +3543,7 @@ int bdrv_truncate(BlockDriverState *bs, int64_t >> offset) >> ret = drv->bdrv_truncate(bs, offset); >> if (ret == 0) { >> ret = refresh_total_sectors(bs, offset >> BDRV_SECTOR_BITS); >> + bdrv_dirty_bitmap_truncate(bs); >> if (bs->blk) { >> blk_dev_resize_cb(bs->blk); >> } >> @@ -5562,6 +5563,27 @@ BdrvDirtyBitmap >> *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, >> return parent; >> } >> +static void dirty_bitmap_truncate(BdrvDirtyBitmap *bitmap, uint64_t >> size) >> +{ >> + /* Should only be frozen during a block backup job, which should >> have >> + * blocked any resize actions. */ >> + assert(!bdrv_dirty_bitmap_frozen(bitmap)); >> + hbitmap_truncate(bitmap->bitmap, size); >> +} >> + >> +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs) >> +{ >> + BdrvDirtyBitmap *bitmap; >> + uint64_t size = bdrv_nb_sectors(bs); >> + >> + QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { >> + if (bdrv_dirty_bitmap_frozen(bitmap)) { >> + continue; >> + } > > Hm! > > The assert() above doesn't do anything because this condition will just > skip over frozen bitmaps. Maybe we should drop it? > > I guess my R-b stands since bdrv_dirty_bitmap_frozen(bitmap) will always > be false anyway (hence the assertion), but it would stand with this > block dropped, too. > > Max > It's there for parity with the other bdrv helpers that perform a similar check. I am guarding against, in the future, any potential users from deciding to call this function directly for whichever reason. Requesting an action on a drive that contains bitmaps that are not ready for the action is OK. Requesting an action on a bitmap that is not ready for the action should never happen, hence the 'documentation assert.' My default action will be to leave it in. --js >> + dirty_bitmap_truncate(bitmap, size); >> + } >> +} >> + >> void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap >> *bitmap) >> { >> BdrvDirtyBitmap *bm, *next; >> diff --git a/include/block/block.h b/include/block/block.h >> index a8c6369..3a85690 100644 >> --- a/include/block/block.h >> +++ b/include/block/block.h >> @@ -454,6 +454,7 @@ BdrvDirtyBitmap >> *bdrv_create_dirty_bitmap(BlockDriverState *bs, >> uint32_t granularity, >> const char *name, >> Error **errp); >> +void bdrv_dirty_bitmap_truncate(BlockDriverState *bs); >> int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs, >> BdrvDirtyBitmap *bitmap, >> Error **errp); >> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h >> index c19c1cb..a75157e 100644 >> --- a/include/qemu/hbitmap.h >> +++ b/include/qemu/hbitmap.h >> @@ -65,6 +65,16 @@ struct HBitmapIter { >> HBitmap *hbitmap_alloc(uint64_t size, int granularity); >> /** >> + * hbitmap_truncate: >> + * @hb: The bitmap to change the size of. >> + * @size: The number of elements to change the bitmap to accommodate. >> + * >> + * truncate or grow an existing bitmap to accommodate a new number of >> elements. >> + * This may invalidate existing HBitmapIterators. >> + */ >> +void hbitmap_truncate(HBitmap *hb, uint64_t size); >> + >> +/** >> * hbitmap_merge: >> * @a: The bitmap to store the result in. >> * @b: The bitmap to merge into @a. >> diff --git a/util/hbitmap.c b/util/hbitmap.c >> index 962ff29..dd8c2f3 100644 >> --- a/util/hbitmap.c >> +++ b/util/hbitmap.c >> @@ -90,6 +90,9 @@ struct HBitmap { >> * bitmap will still allocate HBITMAP_LEVELS arrays. >> */ >> unsigned long *levels[HBITMAP_LEVELS]; >> + >> + /* The length of each levels[] array. */ >> + uint64_t sizes[HBITMAP_LEVELS]; >> }; >> /* Advance hbi to the next nonzero word and return it. hbi->pos >> @@ -384,6 +387,7 @@ HBitmap *hbitmap_alloc(uint64_t size, int >> granularity) >> hb->granularity = granularity; >> for (i = HBITMAP_LEVELS; i-- > 0; ) { >> size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); >> + hb->sizes[i] = size; >> hb->levels[i] = g_new0(unsigned long, size); >> } >> @@ -396,6 +400,57 @@ HBitmap *hbitmap_alloc(uint64_t size, int >> granularity) >> return hb; >> } >> +void hbitmap_truncate(HBitmap *hb, uint64_t size) >> +{ >> + bool truncate; >> + unsigned i; >> + uint64_t num_elements = size; >> + uint64_t old; >> + >> + /* Size comes in as logical elements, adjust for granularity. */ >> + size = (size + (1ULL << hb->granularity) - 1) >> hb->granularity; >> + assert(size <= ((uint64_t)1 << HBITMAP_LOG_MAX_SIZE)); >> + truncate = size < hb->size; >> + >> + if (size == hb->size) { >> + /* A hard day's work */ >> + return; >> + } >> + >> + hb->size = size; >> + for (i = HBITMAP_LEVELS; i-- > 0; ) { >> + size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1); >> + if (hb->sizes[i] == size) { >> + continue; >> + } >> + old = hb->sizes[i]; >> + hb->sizes[i] = size; >> + hb->levels[i] = g_realloc_n(hb->levels[i], size, >> sizeof(unsigned long)); >> + if (!truncate) { >> + memset(&hb->levels[i][old], 0x00, >> + (size - old) * sizeof(*hb->levels[i])); >> + } >> + } >> + assert(size == 1); >> + >> + /* Clear out any "extra space" we may have that the user didn't >> request: >> + * It may have garbage data in it, now. */ >> + if (truncate) { >> + /* Due to granularity fuzziness, we may accidentally reset >> some of >> + * the last bits that are actually valid. So, record the >> current value, >> + * reset the "dead range," then re-set the one element we >> care about. */ >> + uint64_t fix_count = (hb->size << hb->granularity) - >> num_elements; >> + if (fix_count) { >> + bool set = hbitmap_get(hb, num_elements - 1); >> + hbitmap_reset(hb, num_elements, fix_count); >> + if (set) { >> + hbitmap_set(hb, num_elements - 1, 1); >> + } >> + } >> + } >> +} >> + >> + >> /** >> * Given HBitmaps A and B, let A := A (BITOR) B. >> * Bitmap B will not be modified. >