From 8474f0f611f4372bd4f98c6df92f50566f631db0 Mon Sep 17 00:00:00 2001 Message-Id: <8474f0f611f4372bd4f98c6df92f50566f631db0@dist-git> From: Michal Privoznik Date: Mon, 8 Mar 2021 12:57:33 +0100 Subject: [PATCH] virdevmapper: Handle kernel without device-mapper support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In one of my latest patch (v6.6.0~30) I was trying to remove libdevmapper use in favor of our own implementation. However, the code did not take into account that device mapper can be not compiled into the kernel (e.g. be a separate module that's not loaded) in which case /proc/devices won't have the device-mapper major number and thus virDevMapperGetTargets() and/or virIsDevMapperDevice() fails. However, such failure is safe to ignore, because if device mapper is missing then there can't be any multipath devices and thus we don't need to allow the deps in CGroups, nor create them in the domain private namespace, etc. Fixes: 22494556542c676d1b9e7f1c1f2ea13ac17e1e3e Reported-by: Andrea Bolognani Reported-by: Christian Ehrhardt Signed-off-by: Michal Privoznik Reviewed-by: Peter Krempa Reviewed-by: Christian Ehrhardt Tested-by: Christian Ehrhardt (cherry picked from commit feb8564a3cc63bc8f68284063d53ec0d2d81a1cc) Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1933557 Signed-off-by: Michal Privoznik Message-Id: <11f41c0fd7b7c8365e24398173cb0bb2f8e785de.1615203117.git.mprivozn@redhat.com> Reviewed-by: Ján Tomko --- src/util/virdevmapper.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/src/util/virdevmapper.c b/src/util/virdevmapper.c index 725de736c1..a76fe95922 100644 --- a/src/util/virdevmapper.c +++ b/src/util/virdevmapper.c @@ -57,6 +57,9 @@ virDevMapperGetMajor(unsigned int *major) VIR_AUTOSTRINGLIST lines = NULL; size_t i; + if (!virFileExists(CONTROL_PATH)) + return -2; + if (virFileReadAll(PROC_DEVICES, BUF_SIZE, &buf) < 0) return -1; @@ -130,8 +133,13 @@ virDMOpen(void) memset(&dm, 0, sizeof(dm)); - if ((controlFD = open(CONTROL_PATH, O_RDWR)) < 0) + if ((controlFD = open(CONTROL_PATH, O_RDWR)) < 0) { + if (errno == ENOENT) + return -2; + + virReportSystemError(errno, _("Unable to open %s"), CONTROL_PATH); return -1; + } if (!virDMIoctl(controlFD, DM_VERSION, &dm, &tmp)) { virReportSystemError(errno, "%s", @@ -313,8 +321,16 @@ virDevMapperGetTargets(const char *path, * consist of devices or yet another targets. If that's the * case, we have to stop recursion somewhere. */ - if ((controlFD = virDMOpen()) < 0) + if ((controlFD = virDMOpen()) < 0) { + if (controlFD == -2) { + /* The CONTROL_PATH doesn't exist. Probably the + * module isn't loaded, yet. Don't error out, just + * exit. */ + return 0; + } + return -1; + } return virDevMapperGetTargetsImpl(controlFD, path, devPaths, ttl); } -- 2.31.0