From patchwork Tue Mar 9 01:13:13 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rob Earhart X-Patchwork-Id: 47143 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id E3254B7D0B for ; Tue, 9 Mar 2010 12:13:58 +1100 (EST) Received: from localhost ([127.0.0.1]:48181 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Noo1C-0007tu-4h for incoming@patchwork.ozlabs.org; Mon, 08 Mar 2010 20:13:54 -0500 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Noo0f-0007tp-78 for qemu-devel@nongnu.org; Mon, 08 Mar 2010 20:13:21 -0500 Received: from [199.232.76.173] (port=51277 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Noo0e-0007th-L2 for qemu-devel@nongnu.org; Mon, 08 Mar 2010 20:13:20 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Noo0c-000567-3a for qemu-devel@nongnu.org; Mon, 08 Mar 2010 20:13:20 -0500 Received: from smtp-out.google.com ([216.239.33.17]:38778) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Noo0b-00055x-Fw for qemu-devel@nongnu.org; Mon, 08 Mar 2010 20:13:17 -0500 Received: from spaceape13.eur.corp.google.com (spaceape13.eur.corp.google.com [172.28.16.147]) by smtp-out.google.com with ESMTP id o291DFgd010621 for ; Tue, 9 Mar 2010 01:13:15 GMT DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=google.com; s=beta; t=1268097195; bh=u7WsdMb8aB5vhbs+ByfKecGDujo=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=ytZ8URhywRROqM8DZhXvwDUB3yYZ7w3iQem6cP6TixiaxYN0P6fJfwq80NGm83O4a ZoOCD8Kt7rnFY1Z2u1rzg== DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:date:message-id:subject:from:to:content-type:x-system-of-record; b=p1Om8rQWnFBvXSul3wiJGdrBIjNLpPcxW9kzxvj9yXdbkMh1EnbverAqQFXgJXFQt Uk7F6LY28z/bIAyLm62uA== Received: from qyk38 (qyk38.prod.google.com [10.241.83.166]) by spaceape13.eur.corp.google.com with ESMTP id o291CvYI008007 for ; Mon, 8 Mar 2010 17:13:14 -0800 Received: by qyk38 with SMTP id 38so3929115qyk.27 for ; Mon, 08 Mar 2010 17:13:13 -0800 (PST) MIME-Version: 1.0 Received: by 10.220.124.149 with SMTP id u21mr185172vcr.208.1268097193581; Mon, 08 Mar 2010 17:13:13 -0800 (PST) Date: Mon, 8 Mar 2010 17:13:13 -0800 Message-ID: <377f3a9b1003081713v6f39fae2sb15f80073d13215a@mail.gmail.com> From: Rob Earhart To: qemu-devel@nongnu.org X-System-Of-Record: true X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 3) Subject: [Qemu-devel] [PATCH] Use snapshots from backing disks X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Modify the snapshot load path to find and load snapshots contained in backing disks, useful when the current disk is a differencing disk. Add the source of a snapshot when listing snapshots. This should only break backwards compatibility for scenarios depending on not being able to load snapshots from backing disks (which doesn't seem like a problem), and for code which parses the snapshot list output (if any). Signed-off-by: Rob Earhart --- block.c | 10 +++++ block.h | 2 + block/qcow2-snapshot.c | 105 ++++++++++++++++++++++++++++++++++++------------ qemu-img.c | 25 +++++++----- savevm.c | 92 +++++++++++++++++++++++++++++------------- 5 files changed, 170 insertions(+), 64 deletions(-) if (ret < 0) { @@ -1696,7 +1724,7 @@ void do_savevm(Monitor *mon, const QDict *qdict) memset(sn, 0, sizeof(*sn)); if (name) { - ret = bdrv_snapshot_find(bs, old_sn, name); + ret = bdrv_snapshot_find(bs, old_sn, name, NULL); if (ret >= 0) { pstrcpy(sn->name, sizeof(sn->name), old_sn->name); pstrcpy(sn->id_str, sizeof(sn->id_str), old_sn->id_str); @@ -1759,7 +1787,7 @@ void do_savevm(Monitor *mon, const QDict *qdict) int load_vmstate(Monitor *mon, const char *name) { DriveInfo *dinfo; - BlockDriverState *bs, *bs1; + BlockDriverState *bs, *bs1, *sn_bs; QEMUSnapshotInfo sn; QEMUFile *f; int ret; @@ -1804,12 +1832,12 @@ int load_vmstate(Monitor *mon, const char *name) } /* Don't even try to load empty VM states */ - ret = bdrv_snapshot_find(bs, &sn, name); + ret = bdrv_snapshot_find(bs, &sn, name, &sn_bs); if ((ret >= 0) && (sn.vm_state_size == 0)) return -EINVAL; /* restore the VM state */ - f = qemu_fopen_bdrv(bs, 0); + f = qemu_fopen_bdrv(sn_bs, 0); if (!f) { monitor_printf(mon, "Could not open VM state file\n"); return -EINVAL; @@ -1876,17 +1904,25 @@ void do_info_snapshots(Monitor *mon) } monitor_printf(mon, "\n"); - nb_sns = bdrv_snapshot_list(bs, &sn_tab); - if (nb_sns < 0) { - monitor_printf(mon, "bdrv_snapshot_list: error %d\n", nb_sns); - return; - } - monitor_printf(mon, "Snapshot list (from %s):\n", - bdrv_get_device_name(bs)); - monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL)); - for(i = 0; i < nb_sns; i++) { - sn = &sn_tab[i]; - monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn)); + for (; bs; bs = bdrv_get_backing_bdrv(bs)) { + nb_sns = bdrv_snapshot_list(bs, &sn_tab); + if (nb_sns < 0) { + monitor_printf(mon, "bdrv_snapshot_list: error %d\n", nb_sns); + continue; + } + const char* device_name = bdrv_get_device_name(bs); + if (device_name && device_name[0]) { + monitor_printf(mon, "Snapshot list (device %s, from %s):\n", + device_name, bdrv_get_filename(bs)); + } else { + monitor_printf(mon, "Snapshot list (from %s):\n", + bdrv_get_filename(bs)); + } + monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL)); + for(i = 0; i < nb_sns; i++) { + sn = &sn_tab[i]; + monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn)); + } + qemu_free(sn_tab); } - qemu_free(sn_tab); } diff --git a/block.c b/block.c index 31d1ba4..3588700 100644 --- a/block.c +++ b/block.c @@ -1481,6 +1481,16 @@ void bdrv_get_backing_filename(BlockDriverState *bs, } } +const char *bdrv_get_filename(BlockDriverState *bs) +{ + return bs->filename; +} + +BlockDriverState* bdrv_get_backing_bdrv(BlockDriverState *bs) +{ + return bs->backing_hd; +} + int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors) { diff --git a/block.h b/block.h index edf5704..1d04322 100644 --- a/block.h +++ b/block.h @@ -179,6 +179,8 @@ int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi); const char *bdrv_get_encrypted_filename(BlockDriverState *bs); void bdrv_get_backing_filename(BlockDriverState *bs, char *filename, int filename_size); +const char *bdrv_get_filename(BlockDriverState *bs); +BlockDriverState* bdrv_get_backing_bdrv(BlockDriverState *bs); int bdrv_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info); int bdrv_snapshot_goto(BlockDriverState *bs, diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 8ddaea2..ca06fcf 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -191,16 +191,23 @@ static int qcow_write_snapshots(BlockDriverState *bs) static void find_new_snapshot_id(BlockDriverState *bs, char *id_str, int id_str_size) { - BDRVQcowState *s = bs->opaque; - QCowSnapshot *sn; - int i, id, id_max = 0; + int id_max = 0; + + assert(bs); + + do { + BDRVQcowState *s = bs->opaque; + QCowSnapshot *sn; + int i, id; + + for(i = 0; i < s->nb_snapshots; i++) { + sn = s->snapshots + i; + id = strtoul(sn->id_str, NULL, 10); + if (id > id_max) + id_max = id; + } + } while ((bs = bdrv_get_backing_bdrv(bs))); - for(i = 0; i < s->nb_snapshots; i++) { - sn = s->snapshots + i; - id = strtoul(sn->id_str, NULL, 10); - if (id > id_max) - id_max = id; - } snprintf(id_str, id_str_size, "%d", id_max + 1); } @@ -316,41 +323,88 @@ int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) { BDRVQcowState *s = bs->opaque; QCowSnapshot *sn; - int i, snapshot_index, l1_size2; + int i, snapshot_index, l1_size2, ret; snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); - if (snapshot_index < 0) - return -ENOENT; + + if (snapshot_index < 0) { + /* if there is a backing file, use it. In this case, the + * current image needs to be reset to be consistent + */ + if (bs->backing_hd) { + ret = bdrv_snapshot_goto(bs->backing_hd, snapshot_id); + if (ret < 0) { + return ret; + } + /* reset the sectors of the current image (Note: there can + * still be snapshots, so the refcounts must be kept + * consistent) + */ + if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, + s->l1_size, -1) < 0) { + return -EIO; + } + l1_size2 = s->l1_size * sizeof(uint64_t); + memset(s->l1_table, 0, l1_size2); + if (bdrv_pwrite(s->hd, s->l1_table_offset, + s->l1_table, l1_size2) != l1_size2) { + return -EIO; + } + return 0; + } else { + return -ENOENT; + } + } + + assert(0 <= snapshot_index); + sn = &s->snapshots[snapshot_index]; - if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0) - goto fail; + /* if the file is read-only, all can be done by updating the + * in-memory L1 table. Otherwise, we'll need to do some writes. + */ - if (qcow2_grow_l1_table(bs, sn->l1_size) < 0) - goto fail; + if (!bs->read_only) { + if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, + s->l1_size, -1) + < 0) { + return -EIO; + } + } + + if (qcow2_grow_l1_table(bs, sn->l1_size) < 0) { + return -EIO; + } s->l1_size = sn->l1_size; l1_size2 = s->l1_size * sizeof(uint64_t); /* copy the snapshot l1 table to the current l1 table */ if (bdrv_pread(s->hd, sn->l1_table_offset, - s->l1_table, l1_size2) != l1_size2) - goto fail; - if (bdrv_pwrite(s->hd, s->l1_table_offset, - s->l1_table, l1_size2) != l1_size2) - goto fail; + s->l1_table, l1_size2) != l1_size2) { + return -EIO; + } + if (!bs->read_only) { + if (bdrv_pwrite(s->hd, s->l1_table_offset, + s->l1_table, l1_size2) != l1_size2) { + return -EIO; + } + } for(i = 0;i < s->l1_size; i++) { be64_to_cpus(&s->l1_table[i]); } - if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0) - goto fail; + if (!bs->read_only) { + if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, + s->l1_size, 1) + < 0) { + return -EIO; + } + } #ifdef DEBUG_ALLOC qcow2_check_refcounts(bs); #endif return 0; - fail: - return -EIO; } int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id) @@ -416,4 +470,3 @@ int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab) *psn_tab = sn_tab; return s->nb_snapshots; } - diff --git a/qemu-img.c b/qemu-img.c index 0c9f2d4..345a768 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -873,16 +873,21 @@ static void dump_snapshots(BlockDriverState *bs) int nb_sns, i; char buf[256]; - nb_sns = bdrv_snapshot_list(bs, &sn_tab); - if (nb_sns <= 0) - return; - printf("Snapshot list:\n"); - printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL)); - for(i = 0; i < nb_sns; i++) { - sn = &sn_tab[i]; - printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn)); - } - qemu_free(sn_tab); + assert(bs); + + do { + nb_sns = bdrv_snapshot_list(bs, &sn_tab); + if (nb_sns <= 0) + continue; + printf("Snapshot list (from %s):\n", + bdrv_get_filename(bs)); + printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL)); + for(i = 0; i < nb_sns; i++) { + sn = &sn_tab[i]; + printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn)); + } + qemu_free(sn_tab); + } while ((bs = bdrv_get_backing_bdrv(bs))); } static int img_info(int argc, char **argv) diff --git a/savevm.c b/savevm.c index 2fd3de6..8a81c42 100644 --- a/savevm.c +++ b/savevm.c @@ -1616,25 +1616,53 @@ static BlockDriverState *get_bs_snapshots(void) return bs; } +/* Find a snapshot with the given name. + * sn_bs is an out parameter: if NULL, only the current BlockDriverState (bs) + * is checked; otherwise, *sb_bs is set to point to the backing block driver + * state where the found snapshot resides. + */ static int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info, - const char *name) + const char *name, BlockDriverState **sn_bs) { QEMUSnapshotInfo *sn_tab, *sn; int nb_sns, i, ret; + assert(bs); + ret = -ENOENT; - nb_sns = bdrv_snapshot_list(bs, &sn_tab); - if (nb_sns < 0) - return ret; - for(i = 0; i < nb_sns; i++) { - sn = &sn_tab[i]; - if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) { - *sn_info = *sn; - ret = 0; + do { + nb_sns = bdrv_snapshot_list(bs, &sn_tab); + if (nb_sns < 0) { + if (nb_sns == -ENOTSUP) { + /* If this device does not support snapshots, + * its backing file still might; continue on + * to the backing file. + */ + continue; + } else { + return ret; + } + } + for (i = 0; i < nb_sns; i++) { + sn = &sn_tab[i]; + if (!strcmp(sn->id_str, name) || !strcmp(sn->name, name)) { + *sn_info = *sn; + if (sn_bs != 0) { + *sn_bs = bs; + } + ret = 0; + break; + } + } + qemu_free(sn_tab); + if (ret == 0) { break; } - } - qemu_free(sn_tab); + if (!sn_bs) { + break; + } + } while ((bs = bdrv_get_backing_bdrv(bs))); + return ret; } @@ -1651,7 +1679,7 @@ static int del_existing_snapshots(Monitor *mon, const char *name) QTAILQ_FOREACH(dinfo, &drives, next) { bs = dinfo->bdrv; if (bdrv_can_snapshot(bs) && - bdrv_snapshot_find(bs, snapshot, name) >= 0) + bdrv_snapshot_find(bs, snapshot, name, NULL) >= 0) { ret = bdrv_snapshot_delete(bs, name);