From patchwork Fri Mar 27 10:20:46 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 455371 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 84FD214008F for ; Fri, 27 Mar 2015 21:21:35 +1100 (AEDT) Received: from localhost ([::1]:49298 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YbROP-00079A-LT for incoming@patchwork.ozlabs.org; Fri, 27 Mar 2015 06:21:33 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36354) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YbRNq-0005oy-QI for qemu-devel@nongnu.org; Fri, 27 Mar 2015 06:20:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YbRNo-0003Qo-TH for qemu-devel@nongnu.org; Fri, 27 Mar 2015 06:20:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40979) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YbRNo-0003Qe-LW for qemu-devel@nongnu.org; Fri, 27 Mar 2015 06:20:56 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t2RAKshm001572 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 27 Mar 2015 06:20:54 -0400 Received: from localhost (ovpn-112-58.ams2.redhat.com [10.36.112.58]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t2RAKrOu023002; Fri, 27 Mar 2015 06:20:54 -0400 From: Stefan Hajnoczi To: Date: Fri, 27 Mar 2015 10:20:46 +0000 Message-Id: <1427451648-29128-3-git-send-email-stefanha@redhat.com> In-Reply-To: <1427451648-29128-1-git-send-email-stefanha@redhat.com> References: <1427451648-29128-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Peter Maydell , Fam Zheng , Stefan Hajnoczi Subject: [Qemu-devel] [PULL for-2.3 2/4] block: Fix unaligned zero write X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Fam Zheng If the zero write is not aligned, bdrv_co_do_pwritev will segfault because of accessing to the NULL qiov passed in by bdrv_co_write_zeroes. Fix this by allocating a local qiov in bdrv_co_do_pwritev if the request is not aligned. (In this case the padding iovs are necessary anyway, so it doesn't hurt.) Also add a check at the end of bdrv_co_do_pwritev to clear the zero flag if padding is involved. Signed-off-by: Fam Zheng Message-id: 1427160230-4489-2-git-send-email-famz@redhat.com Signed-off-by: Stefan Hajnoczi --- block.c | 45 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-) diff --git a/block.c b/block.c index 0fe97de..f2f8ae7 100644 --- a/block.c +++ b/block.c @@ -3118,6 +3118,19 @@ out: return ret; } +static inline uint64_t bdrv_get_align(BlockDriverState *bs) +{ + /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */ + return MAX(BDRV_SECTOR_SIZE, bs->request_alignment); +} + +static inline bool bdrv_req_is_aligned(BlockDriverState *bs, + int64_t offset, size_t bytes) +{ + int64_t align = bdrv_get_align(bs); + return !(offset & (align - 1) || (bytes & (align - 1))); +} + /* * Handle a read request in coroutine context */ @@ -3128,8 +3141,7 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs, BlockDriver *drv = bs->drv; BdrvTrackedRequest req; - /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */ - uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment); + uint64_t align = bdrv_get_align(bs); uint8_t *head_buf = NULL; uint8_t *tail_buf = NULL; QEMUIOVector local_qiov; @@ -3371,8 +3383,7 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs, BdrvRequestFlags flags) { BdrvTrackedRequest req; - /* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */ - uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment); + uint64_t align = bdrv_get_align(bs); uint8_t *head_buf = NULL; uint8_t *tail_buf = NULL; QEMUIOVector local_qiov; @@ -3471,6 +3482,10 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs, bytes = ROUND_UP(bytes, align); } + if (use_local_qiov) { + /* Local buffer may have non-zero data. */ + flags &= ~BDRV_REQ_ZERO_WRITE; + } ret = bdrv_aligned_pwritev(bs, &req, offset, bytes, use_local_qiov ? &local_qiov : qiov, flags); @@ -3511,14 +3526,32 @@ int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs, int64_t sector_num, int nb_sectors, BdrvRequestFlags flags) { + int ret; + trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags); if (!(bs->open_flags & BDRV_O_UNMAP)) { flags &= ~BDRV_REQ_MAY_UNMAP; } + if (bdrv_req_is_aligned(bs, sector_num << BDRV_SECTOR_BITS, + nb_sectors << BDRV_SECTOR_BITS)) { + ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL, + BDRV_REQ_ZERO_WRITE | flags); + } else { + uint8_t *buf; + QEMUIOVector local_qiov; + size_t bytes = nb_sectors << BDRV_SECTOR_BITS; - return bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL, - BDRV_REQ_ZERO_WRITE | flags); + buf = qemu_memalign(bdrv_opt_mem_align(bs), bytes); + memset(buf, 0, bytes); + qemu_iovec_init(&local_qiov, 1); + qemu_iovec_add(&local_qiov, buf, bytes); + + ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, &local_qiov, + BDRV_REQ_ZERO_WRITE | flags); + qemu_vfree(buf); + } + return ret; } /**