From patchwork Mon Oct 31 13:29:38 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 122835 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [140.186.70.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id A66A4B6F7F for ; Tue, 1 Nov 2011 01:51:30 +1100 (EST) Received: from localhost ([::1]:45804 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RKruF-0004vM-0Z for incoming@patchwork.ozlabs.org; Mon, 31 Oct 2011 09:28:03 -0400 Received: from eggs.gnu.org ([140.186.70.92]:40540) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RKrtj-0003Ka-Rz for qemu-devel@nongnu.org; Mon, 31 Oct 2011 09:27:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RKrti-00046s-9L for qemu-devel@nongnu.org; Mon, 31 Oct 2011 09:27:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37794) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RKrti-00046h-1a for qemu-devel@nongnu.org; Mon, 31 Oct 2011 09:27:30 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p9VDRS3l024662 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 31 Oct 2011 09:27:28 -0400 Received: from dhcp-5-188.str.redhat.com (vpn1-7-216.ams2.redhat.com [10.36.7.216]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p9VDRMo9023034; Mon, 31 Oct 2011 09:27:27 -0400 From: Kevin Wolf To: anthony@codemonkey.ws Date: Mon, 31 Oct 2011 14:29:38 +0100 Message-Id: <1320067830-12093-4-git-send-email-kwolf@redhat.com> In-Reply-To: <1320067830-12093-1-git-send-email-kwolf@redhat.com> References: <1320067830-12093-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [Qemu-devel] [PATCH 03/55] Teach block/vdi about "discarded" (no longer allocated) blocks 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: Eric Sunshine An entry in the VDI block map will hold an offset to the actual block if the block is allocated, or one of two specially-interpreted values if not allocated. Using VirtualBox terminology, value VDI_IMAGE_BLOCK_FREE (0xffffffff) represents a never-allocated block (semantically arbitrary content). VDI_IMAGE_BLOCK_ZERO (0xfffffffe) represents a "discarded" block (semantically zero-filled). block/vdi knows only about VDI_IMAGE_BLOCK_FREE. Teach it about VDI_IMAGE_BLOCK_ZERO. Signed-off-by: Eric Sunshine Signed-off-by: Kevin Wolf --- block/vdi.c | 23 ++++++++++++++--------- 1 files changed, 14 insertions(+), 9 deletions(-) diff --git a/block/vdi.c b/block/vdi.c index 883046d..523a640 100644 --- a/block/vdi.c +++ b/block/vdi.c @@ -114,8 +114,13 @@ void uuid_unparse(const uuid_t uu, char *out); */ #define VDI_TEXT "<<< QEMU VM Virtual Disk Image >>>\n" -/* Unallocated blocks use this index (no need to convert endianness). */ -#define VDI_UNALLOCATED UINT32_MAX +/* A never-allocated block; semantically arbitrary content. */ +#define VDI_UNALLOCATED 0xffffffffU + +/* A discarded (no longer allocated) block; semantically zero-filled. */ +#define VDI_DISCARDED 0xfffffffeU + +#define VDI_IS_ALLOCATED(X) ((X) < VDI_DISCARDED) #if !defined(CONFIG_UUID) void uuid_generate(uuid_t out) @@ -307,10 +312,10 @@ static int vdi_check(BlockDriverState *bs, BdrvCheckResult *res) /* Check block map and value of blocks_allocated. */ for (block = 0; block < s->header.blocks_in_image; block++) { uint32_t bmap_entry = le32_to_cpu(s->bmap[block]); - if (bmap_entry != VDI_UNALLOCATED) { + if (VDI_IS_ALLOCATED(bmap_entry)) { if (bmap_entry < s->header.blocks_in_image) { blocks_allocated++; - if (bmap[bmap_entry] == VDI_UNALLOCATED) { + if (!VDI_IS_ALLOCATED(bmap[bmap_entry])) { bmap[bmap_entry] = bmap_entry; } else { fprintf(stderr, "ERROR: block index %" PRIu32 @@ -472,7 +477,7 @@ static int vdi_is_allocated(BlockDriverState *bs, int64_t sector_num, n_sectors = nb_sectors; } *pnum = n_sectors; - return bmap_entry != VDI_UNALLOCATED; + return VDI_IS_ALLOCATED(bmap_entry); } static void vdi_aio_cancel(BlockDriverAIOCB *blockacb) @@ -603,7 +608,7 @@ static void vdi_aio_read_cb(void *opaque, int ret) /* prepare next AIO request */ acb->n_sectors = n_sectors; bmap_entry = le32_to_cpu(s->bmap[block_index]); - if (bmap_entry == VDI_UNALLOCATED) { + if (!VDI_IS_ALLOCATED(bmap_entry)) { /* Block not allocated, return zeros, no need to wait. */ memset(acb->buf, 0, n_sectors * SECTOR_SIZE); ret = vdi_schedule_bh(vdi_aio_rw_bh, acb); @@ -685,7 +690,7 @@ static void vdi_aio_write_cb(void *opaque, int ret) if (acb->header_modified) { VdiHeader *header = acb->block_buffer; logout("now writing modified header\n"); - assert(acb->bmap_first != VDI_UNALLOCATED); + assert(VDI_IS_ALLOCATED(acb->bmap_first)); *header = s->header; vdi_header_to_le(header); acb->header_modified = 0; @@ -699,7 +704,7 @@ static void vdi_aio_write_cb(void *opaque, int ret) goto done; } return; - } else if (acb->bmap_first != VDI_UNALLOCATED) { + } else if (VDI_IS_ALLOCATED(acb->bmap_first)) { /* One or more new blocks were allocated. */ uint64_t offset; uint32_t bmap_first; @@ -749,7 +754,7 @@ static void vdi_aio_write_cb(void *opaque, int ret) /* prepare next AIO request */ acb->n_sectors = n_sectors; bmap_entry = le32_to_cpu(s->bmap[block_index]); - if (bmap_entry == VDI_UNALLOCATED) { + if (!VDI_IS_ALLOCATED(bmap_entry)) { /* Allocate new block and write to it. */ uint64_t offset; uint8_t *block;