From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60586) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zu1iy-0005Mi-NS for qemu-devel@nongnu.org; Wed, 04 Nov 2015 12:19:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zu1iv-0003W5-ED for qemu-devel@nongnu.org; Wed, 04 Nov 2015 12:19:52 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:8316 helo=relay.sw.ru) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zu1iv-0003UN-2T for qemu-devel@nongnu.org; Wed, 04 Nov 2015 12:19:49 -0500 From: "Denis V. Lunev" Date: Wed, 4 Nov 2015 20:19:32 +0300 Message-Id: <1446657582-21619-2-git-send-email-den@openvz.org> In-Reply-To: <1446657582-21619-1-git-send-email-den@openvz.org> References: <1446657582-21619-1-git-send-email-den@openvz.org> Subject: [Qemu-devel] [PATCH 01/11] snapshot: create helper to test that block drivers supports snapshots List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , "Denis V. Lunev" , qemu-devel@nongnu.org, Stefan Hajnoczi , Juan Quintela The patch enforces proper locking for this operation. Signed-off-by: Denis V. Lunev CC: Juan Quintela CC: Stefan Hajnoczi CC: Kevin Wolf --- block/snapshot.c | 27 +++++++++++++++++++++++++++ include/block/snapshot.h | 9 +++++++++ migration/savevm.c | 17 ++++------------- 3 files changed, 40 insertions(+), 13 deletions(-) diff --git a/block/snapshot.c b/block/snapshot.c index 89500f2..2ef4545 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -356,3 +356,30 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs, return ret; } + + +/* Group operations. All block drivers are involved. + * These functions will properly handle dataplace (take aio_context_acquire + * when appropriate for appropriate block drivers + * + * Returned block driver will be always locked. + */ + +bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs) +{ + bool ok = true; + BlockDriverState *bs = NULL; + + while ((bs = bdrv_next(bs)) && ok) { + AioContext *ctx = bdrv_get_aio_context(bs); + + aio_context_acquire(ctx); + if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) { + ok = bdrv_can_snapshot(bs); + } + aio_context_release(ctx); + } + + *first_bad_bs = bs; + return ok; +} diff --git a/include/block/snapshot.h b/include/block/snapshot.h index 770d9bb..0a3cf0d 100644 --- a/include/block/snapshot.h +++ b/include/block/snapshot.h @@ -75,4 +75,13 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs, int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs, const char *id_or_name, Error **errp); + + +/* Group operations. All block drivers are involved. + * These functions will properly handle dataplace (take aio_context_acquire + * when appropriate for appropriate block drivers + * + */ +bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs); + #endif diff --git a/migration/savevm.c b/migration/savevm.c index dbcc39a..3ac3f07 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1290,19 +1290,10 @@ void hmp_savevm(Monitor *mon, const QDict *qdict) const char *name = qdict_get_try_str(qdict, "name"); Error *local_err = NULL; - /* Verify if there is a device that doesn't support snapshots and is writable */ - bs = NULL; - while ((bs = bdrv_next(bs))) { - - if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) { - continue; - } - - if (!bdrv_can_snapshot(bs)) { - monitor_printf(mon, "Device '%s' is writable but does not support snapshots.\n", - bdrv_get_device_name(bs)); - return; - } + if (!bdrv_all_can_snapshot(&bs)) { + monitor_printf(mon, "Device '%s' is writable but does not " + "support snapshots.\n", bdrv_get_device_name(bs)); + return; } bs = find_vmstate_bs(); -- 2.5.0