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qemuDomainCreateDeviceRecursive: Support file mount points

Browse Source 
https://bugzilla.redhat.com/show_bug.cgi?id=1462060

When building a qemu namespace we might be dealing with bare
regular files. Files that live under /dev. For instance
/dev/my_awesome_disk:

  <disk type='file' device='disk'>
    <driver name='qemu' type='qcow2'/>
    <source file='/dev/my_awesome_disk'/>
    <target dev='vdc' bus='virtio'/>
  </disk>

  # qemu-img create -f qcow2 /dev/my_awesome_disk 10M

So far we were mknod()-ing them which is
obviously wrong. We need to touch the file and bind mount it to
the original:

1) touch /var/run/libvirt/qemu/fedora.dev/my_awesome_disk
2) mount --bind /dev/my_awesome_disk /var/run/libvirt/qemu/fedora.dev/my_awesome_disk

Later, when the new /dev is built and replaces original /dev the
file is going to live at expected location.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
This commit is contained in:
Michal Privoznik 2017-06-16 13:49:52 +02:00
parent 4fedbac620
commit 4f05f188de
1 changed files with 20 additions and 8 deletions
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28
src/qemu/qemu_domain.c
View File

@ -7721,6 +7721,7 @@ qemuDomainCreateDeviceRecursive(const char *device,
int ret = -1;
bool isLink = false;
bool isDev = false;
bool isReg = false;
bool create = false;
#ifdef WITH_SELINUX
char *tcon = NULL;
@ -7744,6 +7745,7 @@ qemuDomainCreateDeviceRecursive(const char *device,
isLink = S_ISLNK(sb.st_mode);
isDev = S_ISCHR(sb.st_mode) || S_ISBLK(sb.st_mode);
isReg = S_ISREG(sb.st_mode);
/* Here, @device might be whatever path in the system. We
* should create the path in the namespace iff it's "/dev"
@ -7855,16 +7857,12 @@ qemuDomainCreateDeviceRecursive(const char *device,
}
goto cleanup;
}
/* Set the file permissions again: mknod() is affected by the
* current umask, and as such might not have set them correctly */
} else if (isReg) {
if (create &&
chmod(devicePath, sb.st_mode) < 0) {
virReportSystemError(errno,
_("Failed to set permissions for device %s"),
devicePath);
virFileTouch(devicePath, sb.st_mode) < 0)
goto cleanup;
}
/* Just create the file here so that code below sets
* proper owner and mode. Bind mount only after that. */
} else {
virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
_("unsupported device type %s 0%o"),
@ -7884,6 +7882,15 @@ qemuDomainCreateDeviceRecursive(const char *device,
goto cleanup;
}
/* Symlinks don't have mode */
if (!isLink &&
chmod(devicePath, sb.st_mode) < 0) {
virReportSystemError(errno,
_("Failed to set permissions for device %s"),
devicePath);
goto cleanup;
}
/* Symlinks don't have ACLs. */
if (!isLink &&
virFileCopyACLs(device, devicePath) < 0 &&
@ -7916,6 +7923,11 @@ qemuDomainCreateDeviceRecursive(const char *device,
}
#endif
/* Finish mount process started earlier. */
if (isReg &&
virFileBindMountDevice(device, devicePath) < 0)
goto cleanup;
ret = 0;
cleanup:
VIR_FREE(target);