From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37663) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XlGAx-0004mV-FD for qemu-devel@nongnu.org; Mon, 03 Nov 2014 06:52:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XlGAr-0000Xv-Az for qemu-devel@nongnu.org; Mon, 03 Nov 2014 06:51:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41382) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XlGAr-0000X3-2l for qemu-devel@nongnu.org; Mon, 03 Nov 2014 06:51:53 -0500 From: Stefan Hajnoczi Date: Mon, 3 Nov 2014 11:50:25 +0000 Message-Id: <1415015456-25086-23-git-send-email-stefanha@redhat.com> In-Reply-To: <1415015456-25086-1-git-send-email-stefanha@redhat.com> References: <1415015456-25086-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PULL 22/53] qcow2: Implement bdrv_make_empty() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Stefan Hajnoczi , Max Reitz From: Max Reitz Implement this function by making all clusters in the image file fall through to the backing file (by using the recently extended discard). Signed-off-by: Max Reitz Reviewed-by: Eric Blake Reviewed-by: Kevin Wolf Message-id: 1414159063-25977-3-git-send-email-mreitz@redhat.com Signed-off-by: Stefan Hajnoczi --- block/qcow2.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/block/qcow2.c b/block/qcow2.c index d64a4ba..bf871d5 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2230,6 +2230,32 @@ fail: return ret; } +static int qcow2_make_empty(BlockDriverState *bs) +{ + int ret = 0; + uint64_t start_sector; + int sector_step = INT_MAX / BDRV_SECTOR_SIZE; + + for (start_sector = 0; start_sector < bs->total_sectors; + start_sector += sector_step) + { + /* As this function is generally used after committing an external + * snapshot, QCOW2_DISCARD_SNAPSHOT seems appropriate. Also, the + * default action for this kind of discard is to pass the discard, + * which will ideally result in an actually smaller image file, as + * is probably desired. */ + ret = qcow2_discard_clusters(bs, start_sector * BDRV_SECTOR_SIZE, + MIN(sector_step, + bs->total_sectors - start_sector), + QCOW2_DISCARD_SNAPSHOT, true); + if (ret < 0) { + break; + } + } + + return ret; +} + static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; @@ -2676,6 +2702,7 @@ static BlockDriver bdrv_qcow2 = { .bdrv_co_discard = qcow2_co_discard, .bdrv_truncate = qcow2_truncate, .bdrv_write_compressed = qcow2_write_compressed, + .bdrv_make_empty = qcow2_make_empty, .bdrv_snapshot_create = qcow2_snapshot_create, .bdrv_snapshot_goto = qcow2_snapshot_goto, -- 1.9.3