From fb8c44edabd188957fe3e3deb97a605f71c394b8 Mon Sep 17 00:00:00 2001 Message-Id: From: Michal Privoznik Date: Mon, 8 Mar 2021 12:57:32 +0100 Subject: [PATCH] virdevmapper: Don't cache device-mapper major MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The device mapper major is needed in virIsDevMapperDevice() which determines whether given device is managed by device-mapper. This number is obtained by parsing /proc/devices and then stored in a global variable so that the file doesn't have to be parsed again. However, as it turns out this logic is flawed - the major number is not static and can change as it can be specified as a parameter when loading the dm-mod module. Unfortunately, I was not able to come up with a good solution and thus the /proc/devices file is being parsed every time we need the device mapper major. Signed-off-by: Michal Privoznik Reviewed-by: Peter Krempa Reviewed-by: Christian Ehrhardt Tested-by: Christian Ehrhardt (cherry picked from commit 82bb167f0d15b733b23931205be3488b83cb9ec6) Conflicts: - src/util/virdevmapper.c: The VIR_ONCE_GLOBAL_INIT() call was missing a semicolon at EOL which was added there in af36f8a641809556ac18dcc076f996033cb2385c which isn't backported. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1933557 Signed-off-by: Michal Privoznik Message-Id: <206f7453debcfd7a013317989893be8a0688045c.1615203117.git.mprivozn@redhat.com> Reviewed-by: Ján Tomko --- src/util/virdevmapper.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) diff --git a/src/util/virdevmapper.c b/src/util/virdevmapper.c index ebf446d966..725de736c1 100644 --- a/src/util/virdevmapper.c +++ b/src/util/virdevmapper.c @@ -49,11 +49,9 @@ verify(BUF_SIZE > sizeof(struct dm_ioctl)); -static unsigned int virDMMajor; - static int -virDevMapperOnceInit(void) +virDevMapperGetMajor(unsigned int *major) { VIR_AUTOFREE(char *) buf = NULL; VIR_AUTOSTRINGLIST lines = NULL; @@ -72,7 +70,7 @@ virDevMapperOnceInit(void) if (sscanf(lines[i], "%u %ms\n", &maj, &dev) == 2 && STREQ(dev, DM_NAME)) { - virDMMajor = maj; + *major = maj; break; } } @@ -88,9 +86,6 @@ virDevMapperOnceInit(void) } -VIR_ONCE_GLOBAL_INIT(virDevMapper) - - static void * virDMIoctl(int controlFD, int cmd, struct dm_ioctl *dm, char **buf) { @@ -318,9 +313,6 @@ virDevMapperGetTargets(const char *path, * consist of devices or yet another targets. If that's the * case, we have to stop recursion somewhere. */ - if (virDevMapperInitialize() < 0) - return -1; - if ((controlFD = virDMOpen()) < 0) return -1; @@ -332,13 +324,14 @@ bool virIsDevMapperDevice(const char *dev_name) { struct stat buf; + unsigned int major; - if (virDevMapperInitialize() < 0) + if (virDevMapperGetMajor(&major) < 0) return false; if (!stat(dev_name, &buf) && S_ISBLK(buf.st_mode) && - major(buf.st_rdev) == virDMMajor) + major(buf.st_rdev) == major) return true; return false; -- 2.31.0