From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52743) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXrt7-00046q-0q for qemu-devel@nongnu.org; Tue, 17 Mar 2015 09:50:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YXrt2-0001Nd-E5 for qemu-devel@nongnu.org; Tue, 17 Mar 2015 09:50:28 -0400 Message-ID: <5508311D.1070301@redhat.com> Date: Tue, 17 Mar 2015 09:50:21 -0400 From: Max Reitz MIME-Version: 1.0 References: <1426271419-8277-1-git-send-email-jsnow@redhat.com> <1426271419-8277-16-git-send-email-jsnow@redhat.com> In-Reply-To: <1426271419-8277-16-git-send-email-jsnow@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [2.4 PATCH v3 15/19] block: Resize bitmaps on bdrv_truncate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow , 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 2015-03-13 at 14:30, John Snow wrote: > Signed-off-by: John Snow > --- > block.c | 18 +++++++++++++++++ > include/qemu/hbitmap.h | 10 ++++++++++ > util/hbitmap.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 80 insertions(+) > > diff --git a/block.c b/block.c > index 1eee394..f40b014 100644 > --- a/block.c > +++ b/block.c > @@ -113,6 +113,7 @@ static void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, > int nr_sectors); > static void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, > int nr_sectors); > +static void bdrv_dirty_bitmap_truncate(BlockDriverState *bs); > /* If non-zero, use only whitelisted block drivers */ > static int use_bdrv_whitelist; > > @@ -3543,6 +3544,7 @@ 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 +5564,22 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, > return parent; > } > > +/** > + * Truncates _all_ bitmaps attached to a BDS. > + */ > +static 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; > + } > + hbitmap_truncate(bitmap->bitmap, size); > + } > +} > + > void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap) > { > BdrvDirtyBitmap *bm, *next; > 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 ba11fd3..4505ef7 100644 > --- a/util/hbitmap.c > +++ b/util/hbitmap.c > @@ -400,6 +400,58 @@ HBitmap *hbitmap_alloc(uint64_t size, int granularity) > return hb; > } > > +void hbitmap_truncate(HBitmap *hb, uint64_t size) > +{ > + bool shrink; > + 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)); > + shrink = size < hb->size; > + > + /* bit sizes are identical; nothing to do. */ > + if (size == hb->size) { > + return; > + } > + > + /* If we're losing bits, let's clear those bits before we invalidate all of > + * our invariants. This helps keep the bitcount consistent, and will prevent > + * us from carrying around garbage bits beyond the end of the map. > + * > + * Because clearing bits past the end of map might reset bits we care about > + * within the array, record the current value of the last bit we're keeping. > + */ > + if (shrink) { > + bool set = hbitmap_get(hb, num_elements - 1); > + uint64_t fix_count = (hb->size << hb->granularity) - num_elements; > + > + assert(fix_count); > + hbitmap_reset(hb, num_elements, fix_count); > + if (set) { > + hbitmap_set(hb, num_elements - 1, 1); > + } > + } > + > + hb->size = size; > + for (i = HBITMAP_LEVELS; i-- > 0; ) { > + size = MAX(BITS_TO_LONGS(size), 1); Shouldn't this be "size = MAX(BITS_TO_LONGS(size) >> BITS_PER_LEVEL, 1);"? > + if (hb->sizes[i] == size) { > + break; > + } > + old = hb->sizes[i]; > + hb->sizes[i] = size; > + hb->levels[i] = g_realloc(hb->levels[i], size * sizeof(unsigned long)); Any specific reason you got rid of the g_realloc_n()? Apart from these, the changes to v2 look good. Max > + if (!shrink) { > + memset(&hb->levels[i][old], 0x00, > + (size - old) * sizeof(*hb->levels[i])); > + } > + } > +} > + > + > /** > * Given HBitmaps A and B, let A := A (BITOR) B. > * Bitmap B will not be modified.