From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58095) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fPwI3-0001bJ-Pd for qemu-devel@nongnu.org; Mon, 04 Jun 2018 16:41:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fPwI2-000556-OC for qemu-devel@nongnu.org; Mon, 04 Jun 2018 16:41:19 -0400 Date: Mon, 4 Jun 2018 16:41:09 -0400 From: Jeff Cody Message-ID: <20180604204109.GC14298@localhost.localdomain> References: <20180531205046.153256-1-eblake@redhat.com> <20180531205046.153256-3-eblake@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180531205046.153256-3-eblake@redhat.com> Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2 2/8] qcow: Switch get_cluster_offset to be byte-based List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: qemu-devel@nongnu.org, kwolf@redhat.com, qemu-block@nongnu.org, mreitz@redhat.com On Thu, May 31, 2018 at 03:50:40PM -0500, Eric Blake wrote: > We are gradually moving away from sector-based interfaces, towards > byte-based. Make the change for the internal helper function > get_cluster_offset(), by changing n_start and n_end to by byte s/by\ byte/be\ byte/ > offsets rather than sector indices within the cluster being > allocated. However, assert that these values are still > sector-aligned (at least qcrypto_block_encrypt() still wants that). > For now we get that alignment for free because we still use > sector-based driver callbacks. > > A later patch will then switch the qcow driver as a whole over > to byte-based operation; but will still leave things at sector > alignments as it is not worth auditing the qcow image format > to worry about sub-sector requests. > > Signed-off-by: Eric Blake Reviewed-by: Jeff Cody > > --- > v2: assert sector alignment [Max] > --- > block/qcow.c | 29 +++++++++++++++-------------- > 1 file changed, 15 insertions(+), 14 deletions(-) > > diff --git a/block/qcow.c b/block/qcow.c > index 3ba2ca25ea5..42d1bbb7643 100644 > --- a/block/qcow.c > +++ b/block/qcow.c > @@ -345,8 +345,8 @@ static int qcow_reopen_prepare(BDRVReopenState *state, > * > * 0 to not allocate. > * > - * 1 to allocate a normal cluster (for sector indexes 'n_start' to > - * 'n_end') > + * 1 to allocate a normal cluster (for sector-aligned byte offsets 'n_start' > + * to 'n_end' within the cluster) > * > * 2 to allocate a compressed cluster of size > * 'compressed_size'. 'compressed_size' must be > 0 and < > @@ -440,9 +440,10 @@ static int get_cluster_offset(BlockDriverState *bs, > if (!allocate) > return 0; > BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC); > + assert(QEMU_IS_ALIGNED(n_start | n_end, BDRV_SECTOR_SIZE)); > /* allocate a new cluster */ > if ((cluster_offset & QCOW_OFLAG_COMPRESSED) && > - (n_end - n_start) < s->cluster_sectors) { > + (n_end - n_start) < s->cluster_size) { > /* if the cluster is already compressed, we must > decompress it in the case it is not completely > overwritten */ > @@ -480,16 +481,15 @@ static int get_cluster_offset(BlockDriverState *bs, > /* if encrypted, we must initialize the cluster > content which won't be written */ > if (bs->encrypted && > - (n_end - n_start) < s->cluster_sectors) { > - uint64_t start_sect; > + (n_end - n_start) < s->cluster_size) { > + uint64_t start_offset; > assert(s->crypto); > - start_sect = (offset & ~(s->cluster_size - 1)) >> 9; > - for(i = 0; i < s->cluster_sectors; i++) { > + start_offset = offset & ~(s->cluster_size - 1); > + for (i = 0; i < s->cluster_size; i += BDRV_SECTOR_SIZE) { > if (i < n_start || i >= n_end) { > - memset(s->cluster_data, 0x00, 512); > + memset(s->cluster_data, 0x00, BDRV_SECTOR_SIZE); > if (qcrypto_block_encrypt(s->crypto, > - (start_sect + i) * > - BDRV_SECTOR_SIZE, > + start_offset + i, > s->cluster_data, > BDRV_SECTOR_SIZE, > NULL) < 0) { > @@ -497,8 +497,9 @@ static int get_cluster_offset(BlockDriverState *bs, > } > BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); > ret = bdrv_pwrite(bs->file, > - cluster_offset + i * 512, > - s->cluster_data, 512); > + cluster_offset + i, > + s->cluster_data, > + BDRV_SECTOR_SIZE); > if (ret < 0) { > return ret; > } > @@ -758,8 +759,8 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, > n = nb_sectors; > } > ret = get_cluster_offset(bs, sector_num << 9, 1, 0, > - index_in_cluster, > - index_in_cluster + n, &cluster_offset); > + index_in_cluster << 9, > + (index_in_cluster + n) << 9, &cluster_offset); > if (ret < 0) { > break; > } > -- > 2.14.3 > >