On a Wednesday in 2020, Michal Privoznik wrote:
>When attaching a device into a domain, the corresponding /dev
>node might need to be created in the domain's namespace. For some
>types of files we call mknod(), for symlinks we call symlink(),
>but for others - which exist in the host namespace - we need to
>so called 'bind mount' them (which is a way of passing a
>file/directory between mount namespaces). There is this condition
>in qemuDomainAttachDeviceMknodRecursive() which decides whether a
>bind mount will be used, move it into a separate function so that
>it can be reused later.
>
>Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
>---
> src/qemu/qemu_domain_namespace.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
>diff --git a/src/qemu/qemu_domain_namespace.c b/src/qemu/qemu_domain_namespace.c
>index 40c4fb36cb..0c40118938 100644
>--- a/src/qemu/qemu_domain_namespace.c
>+++ b/src/qemu/qemu_domain_namespace.c
>@@ -1253,6 +1253,17 @@ qemuDomainAttachDeviceMknodHelper(pid_t pid G_GNUC_UNUSED,
> }
>
>
>+static bool
>+qemuDomainMknodItemIsBindMounted(mode_t st_mode)
To me, IsBindMounted reads like it's done already, but we yet have to do
that.
Consider:
qemuNamespaceMknodItemNeedsBindMount
>+{
>+ /* A block device S_ISBLK() or a chardev S_ISCHR() is intentionally not
>+ * handled. We want to mknod() it instead of passing in through bind
>+ * mounting. */
>+ return S_ISREG(st_mode) || S_ISFIFO(st_mode) ||
>+ S_ISSOCK(st_mode) || S_ISDIR(st_mode);
>+}
>+
>+
> static int
> qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver,
> virDomainObjPtr vm,
>@@ -1267,7 +1278,6 @@ qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver,
> g_autofree char *target = NULL;
> bool isLink;
> bool isReg;
>- bool isDir;
>
> if (!ttl) {
> virReportSystemError(ELOOP,
>@@ -1289,10 +1299,9 @@ qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver,
> }
>
> isLink = S_ISLNK(data.sb.st_mode);
>- isReg = S_ISREG(data.sb.st_mode) || S_ISFIFO(data.sb.st_mode) || S_ISSOCK(data.sb.st_mode);
>- isDir = S_ISDIR(data.sb.st_mode);
>+ isReg = qemuDomainMknodItemIsBindMounted(data.sb.st_mode);
note that the variable is still misleadingly called isReg.
>
>- if ((isReg || isDir) && STRPREFIX(file, QEMU_DEVPREFIX)) {
>+ if (isReg && STRPREFIX(file, QEMU_DEVPREFIX)) {
> cfg = virQEMUDriverGetConfig(driver);
> if (!(target = qemuDomainGetPreservedMountPath(cfg, vm, file)))
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Jano