qemu-ns: Detect /dev/* mount point duplicates even better

[libvirt] [PATCH] qemu-ns: Detect /dev/* mount point duplicates even better

Posted by Michal Privoznik 7 years, 6 months ago

In 4f1570720218302 I've tried to make duplicates detection for
nested /dev mount better. However, I've missed the obvious case
when there are two same mount points. For instance if:

  # mount --bind /dev/blah /dev/blah
  # mount --bind /dev/blah /dev/blah

Yeah, very unlikely but possible.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_domain.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 702463547..61d28337b 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -8352,7 +8352,7 @@ qemuDomainGetPreservedMounts(virQEMUDriverConfigPtr cfg,
         while (j < nmounts) {
             char *c = STRSKIP(mounts[j], mounts[i]);
 
-            if (c && *c == '/') {
+            if (c && (*c == '/' || *c == '\0')) {
                 VIR_DEBUG("Dropping path %s because of %s", mounts[j], mounts[i]);
                 VIR_DELETE_ELEMENT(mounts, j, nmounts);
             } else {
-- 
2.13.6

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Re: [libvirt] [PATCH] qemu-ns: Detect /dev/* mount point duplicates even better

Posted by Ján Tomko 7 years, 6 months ago

On Wed, Nov 08, 2017 at 04:09:57PM +0100, Michal Privoznik wrote:
>In 4f1570720218302 I've tried to make duplicates detection for
>nested /dev mount better. However, I've missed the obvious case
>when there are two same mount points. For instance if:
>
>  # mount --bind /dev/blah /dev/blah
>  # mount --bind /dev/blah /dev/blah
>
>Yeah, very unlikely but possible.
>
>Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
>---
> src/qemu/qemu_domain.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>

ACK with the likeliness comment removed from the commit message

Jan
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Re: [libvirt] [PATCH] qemu-ns: Detect /dev/* mount point duplicates even better

Posted by Daniel P. Berrange 7 years, 6 months ago

On Wed, Nov 08, 2017 at 04:09:57PM +0100, Michal Privoznik wrote:
> In 4f1570720218302 I've tried to make duplicates detection for
> nested /dev mount better. However, I've missed the obvious case
> when there are two same mount points. For instance if:
> 
>   # mount --bind /dev/blah /dev/blah
>   # mount --bind /dev/blah /dev/blah
> 
> Yeah, very unlikely but possible.

It isn't all that unlikely - libvirt itself sets up mounts just like
that for LXC containers it spawns :-)

> 
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> ---
>  src/qemu/qemu_domain.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 702463547..61d28337b 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -8352,7 +8352,7 @@ qemuDomainGetPreservedMounts(virQEMUDriverConfigPtr cfg,
>          while (j < nmounts) {
>              char *c = STRSKIP(mounts[j], mounts[i]);
>  
> -            if (c && *c == '/') {
> +            if (c && (*c == '/' || *c == '\0')) {
>                  VIR_DEBUG("Dropping path %s because of %s", mounts[j], mounts[i]);
>                  VIR_DELETE_ELEMENT(mounts, j, nmounts);
>              } else {
> -- 
> 2.13.6
> 
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Regards,
Daniel
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