From 7d39e57db8479f4c481636c8c41311f3eabc935f Mon Sep 17 00:00:00 2001 Message-ID: <7d39e57db8479f4c481636c8c41311f3eabc935f.1769699749.git.jdenemar@redhat.com> From: Peter Krempa Date: Mon, 26 Jan 2026 16:49:50 +0100 Subject: [PATCH] qemuSnapshotUpdateBackingStore: Retry as curent user if qemu-img fails The code calls 'qemu-img rebase' to fix the backing store references. The 'qemu-img' process here is run as the 'qemu' user or whatever the defaults and domain XML resolve to. Since this, in certain cases, works also on images which are not part of the backing chain and in privileged deployments thus can be owned by 'root:root' the update may fail (silently). To preserver root-squash deployments but fix also the above case, retry the operation on failure as current user. Signed-off-by: Peter Krempa Reviewed-by: Pavel Hrdina (cherry picked from commit 6bb982178b40768f37c5177f317e73562733530f) https://issues.redhat.com/browse/RHEL-144089 [rhel-10.2] https://issues.redhat.com/browse/RHEL-144090 [rhel-9.8] --- src/qemu/qemu_snapshot.c | 53 ++++++++++++++++++++++++++++------------ 1 file changed, 38 insertions(+), 15 deletions(-) diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c index c23add5103..e30ade9dc8 100644 --- a/src/qemu/qemu_snapshot.c +++ b/src/qemu/qemu_snapshot.c @@ -3698,25 +3698,48 @@ qemuSnapshotUpdateBackingStore(qemuSnapshotDeleteExternalData *data) for (cur = data->disksWithBacking; cur; cur = g_slist_next(cur)) { struct _qemuSnapshotDisksWithBackingStoreData *backingData = cur->data; - g_autoptr(virCommand) cmd = NULL; + /* Try to run the command first as the appropriate user based on the + * domain definition and config. If error is returned retry as current + * (possibly privileged) user for cases where seclabels were reset + * to the default */ + g_autoptr(virCommand) cmd_user_qemu = NULL; + g_autoptr(virCommand) cmd_user_curr = NULL; - if (!(cmd = virCommandNewArgList("qemu-img", - "rebase", - "-u", - "-F", - virStorageFileFormatTypeToString(data->parentDiskSrc->format), - "-f", - virStorageFileFormatTypeToString(backingData->diskSrc->format), - "-b", - data->parentDiskSrc->path, - backingData->diskSrc->path, - NULL))) + if (!(cmd_user_qemu = virCommandNewArgList("qemu-img", + "rebase", + "-u", + "-F", + virStorageFileFormatTypeToString(data->parentDiskSrc->format), + "-f", + virStorageFileFormatTypeToString(backingData->diskSrc->format), + "-b", + data->parentDiskSrc->path, + backingData->diskSrc->path, + NULL))) continue; - virCommandSetUID(cmd, backingData->uid); - virCommandSetGID(cmd, backingData->gid); + virCommandSetUID(cmd_user_qemu, backingData->uid); + virCommandSetGID(cmd_user_qemu, backingData->gid); - ignore_value(virCommandRun(cmd, NULL)); + /* done on success */ + if (virCommandRun(cmd_user_qemu, NULL) == 0) + continue; + + /* retry as current user */ + if (!(cmd_user_curr = virCommandNewArgList("qemu-img", + "rebase", + "-u", + "-F", + virStorageFileFormatTypeToString(data->parentDiskSrc->format), + "-f", + virStorageFileFormatTypeToString(backingData->diskSrc->format), + "-b", + data->parentDiskSrc->path, + backingData->diskSrc->path, + NULL))) + continue; + + ignore_value(virCommandRun(cmd_user_curr, NULL)); } } -- 2.52.0