From patchwork Fri Apr 13 16:23:11 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 152343 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 8ABF2B7003 for ; Sat, 14 Apr 2012 02:24:36 +1000 (EST) Received: from localhost ([::1]:37907 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SIjIY-0000DN-CG for incoming@patchwork.ozlabs.org; Fri, 13 Apr 2012 12:24:34 -0400 Received: from eggs.gnu.org ([208.118.235.92]:45267) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SIjHr-0007Fw-7O for qemu-devel@nongnu.org; Fri, 13 Apr 2012 12:23:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SIjHj-0007v9-Qx for qemu-devel@nongnu.org; Fri, 13 Apr 2012 12:23:50 -0400 Received: from mail-pb0-f45.google.com ([209.85.160.45]:48107) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SIjHj-0007uv-IN for qemu-devel@nongnu.org; Fri, 13 Apr 2012 12:23:43 -0400 Received: by pbcuo5 with SMTP id uo5so4466860pbc.4 for ; Fri, 13 Apr 2012 09:23:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:x-mailer:in-reply-to :references; bh=GPvEXVuEcCb617mm7eKNxnWYhrmJHPuR9FwTFTtE3g0=; b=CAt0oWllYFB5jk57Wwo0zsPNVmPkmF06WBo7j04cVLJT3gdGKXKOLOGeMZ89HFRLbt k8A8bhzMaB30HmM5cQx1c8XPE11lqWx5NK4aqGeR2mNmc76CxN47GM6ICkynaZNqJ69F ZOoyqnQzgHsNS+D2j2/hlqnvnpc/r5mTGdF2dvztGJRoKnv9nRAfjhLpBJpESPARPCMS QXB4/9TqrcKjeVeUYCEzKYJey6dq8a0T+aJmlhNeHO4Ly0xL/sC+CI9u75b+5fen8kuJ rzQiRI0ck+BUfUZCbJSzbQg10n9AaFtfIHq8Th/gbLTWfdnK8u9xNCr4q5HHHjkc0UMl vMlQ== Received: by 10.68.221.35 with SMTP id qb3mr5716736pbc.136.1334334221378; Fri, 13 Apr 2012 09:23:41 -0700 (PDT) Received: from yakj.usersys.redhat.com (93-34-182-16.ip50.fastwebnet.it. [93.34.182.16]) by mx.google.com with ESMTPS id s7sm9116719pbl.31.2012.04.13.09.23.37 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 13 Apr 2012 09:23:40 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Fri, 13 Apr 2012 18:23:11 +0200 Message-Id: <1334334198-30899-2-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.7.9.3 In-Reply-To: <1334334198-30899-1-git-send-email-pbonzini@redhat.com> References: <1334334198-30899-1-git-send-email-pbonzini@redhat.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.85.160.45 Cc: kwolf@redhat.com, fsimonce@redhat.com, mtosatti@redhat.com, eblake@redhat.com, stefanha@linux.vnet.ibm.com Subject: [Qemu-devel] [PATCH 1/8] block: introduce new dirty bitmap functionality 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 Assert that write_compressed is never used with the dirty bitmap. Setting the bits early is wrong, because a coroutine might concurrently examine them and copy incomplete data from the source. Signed-off-by: Paolo Bonzini --- block.c | 51 +++++++++++++++++++++++++++++++++++++++++++++------ block.h | 5 +++-- 2 files changed, 48 insertions(+), 8 deletions(-) diff --git a/block.c b/block.c index 1f4f476..1eb82f2 100644 --- a/block.c +++ b/block.c @@ -1917,7 +1917,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, } if (bs->dirty_bitmap) { - set_dirty_bitmap(bs, sector_num, nb_sectors, 1); + bdrv_set_dirty(bs, sector_num, nb_sectors); } if (bs->wr_highest_sector < sector_num + nb_sectors - 1) { @@ -2700,9 +2700,7 @@ int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num, if (bdrv_check_request(bs, sector_num, nb_sectors)) return -EIO; - if (bs->dirty_bitmap) { - set_dirty_bitmap(bs, sector_num, nb_sectors, 1); - } + assert(!bs->dirty_bitmap); return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors); } @@ -3931,13 +3929,54 @@ int bdrv_get_dirty(BlockDriverState *bs, int64_t sector) if (bs->dirty_bitmap && (sector << BDRV_SECTOR_BITS) < bdrv_getlength(bs)) { - return !!(bs->dirty_bitmap[chunk / (sizeof(unsigned long) * 8)] & - (1UL << (chunk % (sizeof(unsigned long) * 8)))); + return !!(bs->dirty_bitmap[chunk / BITS_PER_LONG] & + (1UL << (chunk % BITS_PER_LONG))); } else { return 0; } } +int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector) +{ + int64_t chunk; + int bit, elem; + + /* Avoid an infinite loop. */ + assert(bs->dirty_count > 0); + + sector = (sector | (BDRV_SECTORS_PER_DIRTY_CHUNK - 1)) + 1; + chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK; + + QEMU_BUILD_BUG_ON(sizeof(bs->dirty_bitmap[0]) * 8 != BITS_PER_LONG); + elem = chunk / BITS_PER_LONG; + bit = chunk % BITS_PER_LONG; + for (;;) { + if (sector >= bs->total_sectors) { + sector = 0; + bit = elem = 0; + } + if (bit == 0 && bs->dirty_bitmap[elem] == 0) { + sector += BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG; + elem++; + } else { + if (bs->dirty_bitmap[elem] & (1UL << bit)) { + return sector; + } + sector += BDRV_SECTORS_PER_DIRTY_CHUNK; + if (++bit == BITS_PER_LONG) { + bit = 0; + elem++; + } + } + } +} + +void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, + int nr_sectors) +{ + set_dirty_bitmap(bs, cur_sector, nr_sectors, 1); +} + void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors) { diff --git a/block.h b/block.h index a0d0200..4d2036e 100644 --- a/block.h +++ b/block.h @@ -344,8 +344,9 @@ void *qemu_blockalign(BlockDriverState *bs, size_t size); void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable); int bdrv_get_dirty(BlockDriverState *bs, int64_t sector); -void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, - int nr_sectors); +void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors); +void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors); +int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector); int64_t bdrv_get_dirty_count(BlockDriverState *bs); void bdrv_enable_copy_on_read(BlockDriverState *bs);