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author | Tomoki Sekiyama <tomoki.sekiyama@hds.com> | 2014-01-13 12:25:29 -0500 |
---|---|---|
committer | Michael Roth <mdroth@linux.vnet.ibm.com> | 2014-02-23 13:11:26 -0600 |
commit | ff8adbcfdbbd9c0f2b01ff8a32bc75082fdd9844 (patch) | |
tree | 5471f51bee348167b44832e72b41513f9623fde4 /qga/vss-win32 | |
parent | 4c1b8f1e8357d85c613d779596e4079cc581d74f (diff) | |
download | qemu-ff8adbcfdbbd9c0f2b01ff8a32bc75082fdd9844.zip qemu-ff8adbcfdbbd9c0f2b01ff8a32bc75082fdd9844.tar.gz qemu-ff8adbcfdbbd9c0f2b01ff8a32bc75082fdd9844.tar.bz2 |
qga: vss-win32: Fix interference with snapshot creation by other VSS requesters
When a VSS requester such as vshadow.exe or diskshadow.exe requests to
create disk snapshots, Windows may choose qemu-ga VSS provider if it is
only provider registered on the system. However, because it provides only a
function to freeze the filesystem, the snapshotting fails.
This patch adds a check into CQGAVssProvider::IsVolumeSupported() to reject
the request from other VSS requesters, so that the other provider is chosen.
The check of requester is done by confirming event channels between
qemu-ga's requester and provider established. To ensure that the events are
initialized when CQGAVssProvider::IsVolumeSupported() is called, it moves
the initialization earlier.
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Gal Hammer <ghammer@redhat.com>
Reviewed-by: Yan Vugenfirer <yvugenfi@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Diffstat (limited to 'qga/vss-win32')
-rw-r--r-- | qga/vss-win32/provider.cpp | 11 | ||||
-rw-r--r-- | qga/vss-win32/requester.cpp | 52 |
2 files changed, 36 insertions, 27 deletions
diff --git a/qga/vss-win32/provider.cpp b/qga/vss-win32/provider.cpp index c3030d8..b233646 100644 --- a/qga/vss-win32/provider.cpp +++ b/qga/vss-win32/provider.cpp @@ -291,8 +291,17 @@ STDMETHODIMP CQGAVssProvider::BeginPrepareSnapshot( STDMETHODIMP CQGAVssProvider::IsVolumeSupported( VSS_PWSZ pwszVolumeName, BOOL *pbSupportedByThisProvider) { - *pbSupportedByThisProvider = TRUE; + HANDLE hEventFrozen; + + /* Check if a requester is qemu-ga by whether an event is created */ + hEventFrozen = OpenEvent(EVENT_ALL_ACCESS, FALSE, EVENT_NAME_FROZEN); + if (!hEventFrozen) { + *pbSupportedByThisProvider = FALSE; + return S_OK; + } + CloseHandle(hEventFrozen); + *pbSupportedByThisProvider = TRUE; return S_OK; } diff --git a/qga/vss-win32/requester.cpp b/qga/vss-win32/requester.cpp index 0a55447..922e74d 100644 --- a/qga/vss-win32/requester.cpp +++ b/qga/vss-win32/requester.cpp @@ -252,6 +252,32 @@ void requester_freeze(int *num_vols, ErrorSet *errset) CoInitialize(NULL); + /* Allow unrestricted access to events */ + InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION); + SetSecurityDescriptorDacl(&sd, TRUE, NULL, FALSE); + sa.nLength = sizeof(sa); + sa.lpSecurityDescriptor = &sd; + sa.bInheritHandle = FALSE; + + vss_ctx.hEventFrozen = CreateEvent(&sa, TRUE, FALSE, EVENT_NAME_FROZEN); + if (!vss_ctx.hEventFrozen) { + err_set(errset, GetLastError(), "failed to create event %s", + EVENT_NAME_FROZEN); + goto out; + } + vss_ctx.hEventThaw = CreateEvent(&sa, TRUE, FALSE, EVENT_NAME_THAW); + if (!vss_ctx.hEventThaw) { + err_set(errset, GetLastError(), "failed to create event %s", + EVENT_NAME_THAW); + goto out; + } + vss_ctx.hEventTimeout = CreateEvent(&sa, TRUE, FALSE, EVENT_NAME_TIMEOUT); + if (!vss_ctx.hEventTimeout) { + err_set(errset, GetLastError(), "failed to create event %s", + EVENT_NAME_TIMEOUT); + goto out; + } + assert(pCreateVssBackupComponents != NULL); hr = pCreateVssBackupComponents(&vss_ctx.pVssbc); if (FAILED(hr)) { @@ -362,32 +388,6 @@ void requester_freeze(int *num_vols, ErrorSet *errset) goto out; } - /* Allow unrestricted access to events */ - InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION); - SetSecurityDescriptorDacl(&sd, TRUE, NULL, FALSE); - sa.nLength = sizeof(sa); - sa.lpSecurityDescriptor = &sd; - sa.bInheritHandle = FALSE; - - vss_ctx.hEventFrozen = CreateEvent(&sa, TRUE, FALSE, EVENT_NAME_FROZEN); - if (!vss_ctx.hEventFrozen) { - err_set(errset, GetLastError(), "failed to create event %s", - EVENT_NAME_FROZEN); - goto out; - } - vss_ctx.hEventThaw = CreateEvent(&sa, TRUE, FALSE, EVENT_NAME_THAW); - if (!vss_ctx.hEventThaw) { - err_set(errset, GetLastError(), "failed to create event %s", - EVENT_NAME_THAW); - goto out; - } - vss_ctx.hEventTimeout = CreateEvent(&sa, TRUE, FALSE, EVENT_NAME_TIMEOUT); - if (!vss_ctx.hEventTimeout) { - err_set(errset, GetLastError(), "failed to create event %s", - EVENT_NAME_TIMEOUT); - goto out; - } - /* * Start VSS quiescing operations. * CQGAVssProvider::CommitSnapshots will kick vss_ctx.hEventFrozen |