From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LKzzS-0004Rx-VJ for qemu-devel@nongnu.org; Thu, 08 Jan 2009 13:52:22 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LKzzS-0004RR-EL for qemu-devel@nongnu.org; Thu, 08 Jan 2009 13:52:22 -0500 Received: from [199.232.76.173] (port=56686 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LKzzS-0004RM-AN for qemu-devel@nongnu.org; Thu, 08 Jan 2009 13:52:22 -0500 Received: from mx2.redhat.com ([66.187.237.31]:48040) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LKzzR-0007YO-Nc for qemu-devel@nongnu.org; Thu, 08 Jan 2009 13:52:22 -0500 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n08IqLKU009966 for ; Thu, 8 Jan 2009 13:52:21 -0500 Message-ID: <49664B62.8040806@redhat.com> Date: Thu, 08 Jan 2009 20:52:18 +0200 From: Uri Lublin MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [PATCH 1/3] block-qcow2: keep highest allocated offset (bytes) Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Uri Lublin From: Uri Lublin We want to know the highest written offset for qcow2 images. This gives a maximal limit (and easy to calculate) on how many bytes were allocated (and maybe freed internally) for a qcow2 image. It can be useful for truncation of backing file images (ftruncate). Also it may be useful for defragmentation later (although we'll need the number of free blocks as well). Signed-off-by: Uri Lublin --- block-qcow2.c | 34 ++++++++++++++++++++++++++++++++++ 1 files changed, 34 insertions(+), 0 deletions(-) diff --git a/block-qcow2.c b/block-qcow2.c index 9aa7261..184c70c 100644 --- a/block-qcow2.c +++ b/block-qcow2.c @@ -143,6 +143,9 @@ typedef struct BDRVQcowState { uint32_t crypt_method_header; AES_KEY aes_encrypt_key; AES_KEY aes_decrypt_key; + + int64_t highest_alloc; /* highest cluester allocated (in clusters) */ + uint64_t snapshots_offset; int snapshots_size; int nb_snapshots; @@ -170,6 +173,8 @@ static void free_clusters(BlockDriverState *bs, #ifdef DEBUG_ALLOC static void check_refcounts(BlockDriverState *bs); #endif +static void scan_refcount(BlockDriverState *bs, int64_t *high); + static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename) { @@ -278,6 +283,8 @@ static int qcow_open(BlockDriverState *bs, const char *filename, int flags) if (refcount_init(bs) < 0) goto fail; + scan_refcount(bs, &s->highest_alloc); + /* read the backing file name */ if (header.backing_file_offset != 0) { len = header.backing_file_size; @@ -2198,6 +2205,29 @@ static int load_refcount_block(BlockDriverState *bs, return 0; } +static void scan_refcount(BlockDriverState *bs, int64_t *high) +{ + BDRVQcowState *s = bs->opaque; + int64_t refcnt_index, cluster_index, cluster_end, h = 0; + + for (refcnt_index=0; refcnt_index < s->refcount_table_size; refcnt_index++){ + if (s->refcount_table[refcnt_index] == 0) { + continue; + } + cluster_index = refcnt_index << (s->cluster_bits - REFCOUNT_SHIFT); + cluster_end = (refcnt_index + 1) << (s->cluster_bits - REFCOUNT_SHIFT); + for ( ; cluster_index < cluster_end; cluster_index++) { + if (get_refcount(bs, cluster_index) == 0) + /* do nothing -- reserved for free counting */; + else + h = cluster_index; + } + } + + if (high) + *high = (h+1); +} + static int get_refcount(BlockDriverState *bs, int64_t cluster_index) { BDRVQcowState *s = bs->opaque; @@ -2238,6 +2268,10 @@ retry: size, (s->free_cluster_index - nb_clusters) << s->cluster_bits); #endif + + if (s->highest_alloc < s->free_cluster_index) + s->highest_alloc = s->free_cluster_index; + return (s->free_cluster_index - nb_clusters) << s->cluster_bits; } -- 1.6.0.6