From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44068) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fPx0u-0000j0-4s for qemu-devel@nongnu.org; Mon, 04 Jun 2018 17:27:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fPx0s-0003Y2-U8 for qemu-devel@nongnu.org; Mon, 04 Jun 2018 17:27:40 -0400 Date: Mon, 4 Jun 2018 17:27:30 -0400 From: Jeff Cody Message-ID: <20180604212730.GE14298@localhost.localdomain> References: <20180531205046.153256-1-eblake@redhat.com> <20180531205046.153256-5-eblake@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180531205046.153256-5-eblake@redhat.com> Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v2 4/8] qcow: Switch qcow_co_writev to byte-based calls 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 03:50:42PM -0500, Eric Blake wrote: > We are gradually moving away from sector-based interfaces, towards > byte-based. Make the change for the internals of the qcow > driver write function, by iterating over offset/bytes instead of > sector_num/nb_sectors, and with a rename of index_in_cluster and > repurposing of n to track bytes instead of sectors. > > A later patch will then switch the qcow driver as a whole over > to byte-based operation. > > Signed-off-by: Eric Blake > > --- > v2: prefer 64-bit * over 23-bit <<, rename variable for legibility [Kevin] > --- > block/qcow.c | 36 +++++++++++++++++------------------- > 1 file changed, 17 insertions(+), 19 deletions(-) > > diff --git a/block/qcow.c b/block/qcow.c > index b90915218ff..44adeba276c 100644 > --- a/block/qcow.c > +++ b/block/qcow.c > @@ -723,13 +723,15 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, > int flags) > { > BDRVQcowState *s = bs->opaque; > - int index_in_cluster; > + int offset_in_cluster; > uint64_t cluster_offset; > int ret = 0, n; > struct iovec hd_iov; > QEMUIOVector hd_qiov; > uint8_t *buf; > void *orig_buf; > + int64_t offset = sector_num * BDRV_SECTOR_SIZE; > + int64_t bytes = nb_sectors * BDRV_SECTOR_SIZE; > > assert(!flags); > s->cluster_cache_offset = -1; /* disable compressed cache */ > @@ -749,16 +751,14 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, > > qemu_co_mutex_lock(&s->lock); > > - while (nb_sectors != 0) { > - > - index_in_cluster = sector_num & (s->cluster_sectors - 1); > - n = s->cluster_sectors - index_in_cluster; > - if (n > nb_sectors) { > - n = nb_sectors; > + while (bytes != 0) { > + offset_in_cluster = offset & (s->cluster_size - 1); > + n = s->cluster_size - offset_in_cluster; > + if (n > bytes) { > + n = bytes; > } > - ret = get_cluster_offset(bs, sector_num << 9, 1, 0, > - index_in_cluster << 9, > - (index_in_cluster + n) << 9, &cluster_offset); > + ret = get_cluster_offset(bs, offset, 1, 0, offset_in_cluster, > + offset_in_cluster + n, &cluster_offset); > if (ret < 0) { > break; > } > @@ -768,30 +768,28 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, > } > if (bs->encrypted) { > assert(s->crypto); > - if (qcrypto_block_encrypt(s->crypto, sector_num * BDRV_SECTOR_SIZE, > - buf, n * BDRV_SECTOR_SIZE, NULL) < 0) { > + if (qcrypto_block_encrypt(s->crypto, offset, buf, n, NULL) < 0) { > ret = -EIO; > break; > } > } > > hd_iov.iov_base = (void *)buf; > - hd_iov.iov_len = n * 512; > + hd_iov.iov_len = n; > qemu_iovec_init_external(&hd_qiov, &hd_iov, 1); > qemu_co_mutex_unlock(&s->lock); > BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); > - ret = bdrv_co_writev(bs->file, > - (cluster_offset >> 9) + index_in_cluster, > - n, &hd_qiov); > + ret = bdrv_co_pwritev(bs->file, cluster_offset + offset_in_cluster, > + n, &hd_qiov, 0); > qemu_co_mutex_lock(&s->lock); > if (ret < 0) { > break; > } > ret = 0; > > - nb_sectors -= n; > - sector_num += n; > - buf += n * 512; > + bytes -= n; > + offset += n; > + buf += n; > } > qemu_co_mutex_unlock(&s->lock); > > -- > 2.14.3 > > Reviewed-by: Jeff Cody