From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57654) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bAZbv-0003AL-JT for qemu-devel@nongnu.org; Wed, 08 Jun 2016 05:17:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bAZbt-0001Ez-H6 for qemu-devel@nongnu.org; Wed, 08 Jun 2016 05:17:14 -0400 From: Kevin Wolf Date: Wed, 8 Jun 2016 11:16:28 +0200 Message-Id: <1465377417-5012-3-git-send-email-kwolf@redhat.com> In-Reply-To: <1465377417-5012-1-git-send-email-kwolf@redhat.com> References: <1465377417-5012-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 02/31] qcow2: simplify logic in qcow2_co_write_zeroes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: "Denis V. Lunev" Unaligned requests will occupy only one cluster. This is true since the previous commit. Simplify the code taking this consideration into account. In other words, the caller is now buggy if it ever passes us an unaligned request that crosses cluster boundaries (the only requests that can cross boundaries will be aligned). There are no other changes so far. Signed-off-by: Denis V. Lunev Reviewed-by: Eric Blake CC: Eric Blake CC: Kevin Wolf Message-Id: <1463476543-3087-3-git-send-email-den@openvz.org> Signed-off-by: Kevin Wolf --- block/qcow2.c | 23 +++++------------------ 1 file changed, 5 insertions(+), 18 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index c9306a7..2f73201 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2438,33 +2438,20 @@ static coroutine_fn int qcow2_co_write_zeroes(BlockDriverState *bs, int tail = (sector_num + nb_sectors) % s->cluster_sectors; if (head != 0 || tail != 0) { - int64_t cl_end = -1; + int64_t cl_start = sector_num - head; - sector_num -= head; - nb_sectors += head; + assert(cl_start + s->cluster_sectors >= sector_num + nb_sectors); - if (tail != 0) { - nb_sectors += s->cluster_sectors - tail; - } + sector_num = cl_start; + nb_sectors = s->cluster_sectors; if (!is_zero_cluster(bs, sector_num)) { return -ENOTSUP; } - if (nb_sectors > s->cluster_sectors) { - /* Technically the request can cover 2 clusters, f.e. 4k write - at s->cluster_sectors - 2k offset. One of these cluster can - be zeroed, one unallocated */ - cl_end = sector_num + nb_sectors - s->cluster_sectors; - if (!is_zero_cluster(bs, cl_end)) { - return -ENOTSUP; - } - } - qemu_co_mutex_lock(&s->lock); /* We can have new write after previous check */ - if (!is_zero_cluster_top_locked(bs, sector_num) || - (cl_end > 0 && !is_zero_cluster_top_locked(bs, cl_end))) { + if (!is_zero_cluster_top_locked(bs, sector_num)) { qemu_co_mutex_unlock(&s->lock); return -ENOTSUP; } -- 1.8.3.1