[PATCH v2 1/2] virdevmapper: Don't cache device-mapper major
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 <mprivozn(a)redhat.com>
---
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 fe7f611496..b24d9377f8 100644
--- a/src/util/virdevmapper.c
+++ b/src/util/virdevmapper.c
@@ -46,11 +46,9 @@
G_STATIC_ASSERT(BUF_SIZE > sizeof(struct dm_ioctl));
-static unsigned int virDMMajor;
-
static int
-virDevMapperOnceInit(void)
+virDevMapperGetMajor(unsigned int *major)
{
g_autofree char *buf = NULL;
VIR_AUTOSTRINGLIST lines = NULL;
@@ -69,7 +67,7 @@ virDevMapperOnceInit(void)
if (sscanf(lines[i], "%u %ms\n", &maj, &dev) == 2 &&
STREQ(dev, DM_NAME)) {
- virDMMajor = maj;
+ *major = maj;
break;
}
}
@@ -85,9 +83,6 @@ virDevMapperOnceInit(void)
}
-VIR_ONCE_GLOBAL_INIT(virDevMapper);
-
-
static void *
virDMIoctl(int controlFD, int cmd, struct dm_ioctl *dm, char **buf)
{
@@ -304,9 +299,6 @@ 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;
@@ -318,13 +310,14 @@ 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;
--
2.26.2