From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33275) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XOPF7-0001l9-MV for qemu-devel@nongnu.org; Mon, 01 Sep 2014 06:53:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XOPEy-0007OS-GM for qemu-devel@nongnu.org; Mon, 01 Sep 2014 06:53:49 -0400 Received: from mail-pa0-x231.google.com ([2607:f8b0:400e:c03::231]:51189) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XOPEy-0007OH-9N for qemu-devel@nongnu.org; Mon, 01 Sep 2014 06:53:40 -0400 Received: by mail-pa0-f49.google.com with SMTP id kq14so11837864pab.8 for ; Mon, 01 Sep 2014 03:53:35 -0700 (PDT) From: Jun Li Date: Mon, 1 Sep 2014 18:52:48 +0800 Message-Id: <1409568798-2292-1-git-send-email-junmuzi@gmail.com> Subject: [Qemu-devel] [PATCH v2] qcow2: add update refcount table realization for update_refcount List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, famz@redhat.com, juli@redhat.com, Jun Li , stefanha@redhat.com When every item of refcount block is NULL, free refcount block and reset the corresponding item of refcount table with NULL. Signed-off-by: Jun Li --- The v2 do following change to modify some potential issue. +------- Here should start from "0". | for (k = 0; k < refcount_block_entries; k++) { if (refcount_block[k] != cpu_to_be16(0)) { ... | | } | | } | +---- Using "0" is more safe. | +-------- This should be "k" not "++k". --- block/qcow2-refcount.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 43665b8..63f36e6 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -586,6 +586,37 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, if (refcount == 0 && s->discard_passthrough[type]) { update_refcount_discard(bs, cluster_offset, s->cluster_size); } + + /* When refcount block is NULL, update refcount table */ + if (block_index == 0) { + int k = block_index; + int refcount_block_entries = s->cluster_size / sizeof(uint16_t); + for (k = 0; k < refcount_block_entries; k++) { + if (refcount_block[k] != cpu_to_be16(0)) { + break; + } + } + + if (k == refcount_block_entries) { + qemu_vfree(refcount_block); + /* update refcount table */ + unsigned int refcount_table_index; + uint64_t data64 = cpu_to_be64(0); + refcount_table_index = cluster_index >> (s->cluster_bits - + REFCOUNT_SHIFT); + ret = bdrv_pwrite_sync(bs->file, + s->refcount_table_offset + + refcount_table_index * + sizeof(uint64_t), + &data64, sizeof(data64)); + if (ret < 0) { + goto fail; + } + + s->refcount_table[refcount_table_index] = data64; + + } + } } ret = 0; -- 1.9.3