[v1] virdevmapper: Always use device name for finding targets

[PATCH] virdevmapper: Always use device name for finding targets

Posted by Bhavin via Devel 5 months, 2 weeks ago

From: Bhavin Gandhi <bhavin192@geeksocket.in>

DM_TABLE_DEPS expects a device name in dm_ioctl.name. In one of the
cases, full path of the device was getting returned causing the ioctl
call to fail with `ENXIO (No such device or address)`.

Also rename the function and variable names to better reflect that we
are dealing with DM device names and not paths.

This got introduced in 22494556542c676d1b9e7f1c1f2ea13ac17e1e3e
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/790

Signed-off-by: Bhavin Gandhi <bhavin192@geeksocket.in>
---
 src/util/virdevmapper.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/util/virdevmapper.c b/src/util/virdevmapper.c
index d0eae671ab..42c86d89cf 100644
--- a/src/util/virdevmapper.c
+++ b/src/util/virdevmapper.c
@@ -164,7 +164,7 @@ virDMOpen(void)
 
 
 static char *
-virDMSanitizepath(const char *path)
+virDMGetDeviceName(const char *path)
 {
     g_autofree char *dmDirPath = NULL;
     struct dirent *ent = NULL;
@@ -205,7 +205,7 @@ virDMSanitizepath(const char *path)
 
         if (stat(tmp, &sb[1]) == 0 &&
             sb[0].st_rdev == sb[1].st_rdev) {
-            return g_steal_pointer(&tmp);
+            return g_strdup(ent->d_name);
         }
     }
 
@@ -219,7 +219,7 @@ virDevMapperGetTargetsImpl(int controlFD,
                            GSList **devPaths,
                            unsigned int ttl)
 {
-    g_autofree char *sanitizedPath = NULL;
+    g_autofree char *deviceName = NULL;
     g_autofree char *buf = NULL;
     struct dm_ioctl dm = { 0 };
     struct dm_target_deps *deps = NULL;
@@ -233,10 +233,10 @@ virDevMapperGetTargetsImpl(int controlFD,
     if (!virIsDevMapperDevice(path))
         return 0;
 
-    if (!(sanitizedPath = virDMSanitizepath(path)))
+    if (!(deviceName = virDMGetDeviceName(path)))
         return 0;
 
-    if (virStrcpy(dm.name, sanitizedPath, DM_NAME_LEN) < 0) {
+    if (virStrcpy(dm.name, deviceName, DM_NAME_LEN) < 0) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("Resolved device mapper name too long"));
         return -1;
-- 
2.49.0

Re: [PATCH] virdevmapper: Always use device name for finding targets

Posted by Daniel P. Berrangé via Devel 5 months, 1 week ago

On Thu, Jul 03, 2025 at 12:39:33AM +0530, Bhavin via Devel wrote:
> From: Bhavin Gandhi <bhavin192@geeksocket.in>
> 
> DM_TABLE_DEPS expects a device name in dm_ioctl.name. In one of the
> cases, full path of the device was getting returned causing the ioctl
> call to fail with `ENXIO (No such device or address)`.
> 
> Also rename the function and variable names to better reflect that we
> are dealing with DM device names and not paths.
> 
> This got introduced in 22494556542c676d1b9e7f1c1f2ea13ac17e1e3e
> Resolves: https://gitlab.com/libvirt/libvirt/-/issues/790
> 
> Signed-off-by: Bhavin Gandhi <bhavin192@geeksocket.in>
> ---
>  src/util/virdevmapper.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

and pushed, thank you for your contribution.

With regards,
Daniel
-- 
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Re: [PATCH] virdevmapper: Always use device name for finding targets

Posted by Bhavin Gandhi via Devel 5 months, 1 week ago

On 03/07/2025 00:39, Bhavin via Devel wrote:

> From: Bhavin Gandhi <bhavin192@geeksocket.in>
> 
> DM_TABLE_DEPS expects a device name in dm_ioctl.name. In one of the
> cases, full path of the device was getting returned causing the ioctl
> call to fail with `ENXIO (No such device or address)`.
> 
> Also rename the function and variable names to better reflect that we
> are dealing with DM device names and not paths.
> 
> This got introduced in 22494556542c676d1b9e7f1c1f2ea13ac17e1e3e
> Resolves: https://gitlab.com/libvirt/libvirt/-/issues/790
> 
> Signed-off-by: Bhavin Gandhi <bhavin192@geeksocket.in>

ping! Can anyone take a look at this patch? It fixes a bug when libvirt 
manages qemu-pr-helper in a multipath setup.