[PATCH v1 11/34] qemuDomainAttachDeviceMknodHelper: Create more files in a single go
Michal Privoznik
mprivozn at redhat.com
Wed Jul 22 09:40:05 UTC 2020
So far, when attaching a device needs two or more /dev nodes
created into a domain, we fork off and run the helper for every
node separately. For majority of devices this is okay, because
they need no or one node created anyway. But the idea is to use
this attach code to build the namespace when starting a domain,
in which case there will be way more nodes than one.
To achieve this, the recursive approach for handling symlinks has
to be turned into an iterative one.
Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
src/qemu/qemu_domain_namespace.c | 298 +++++++++++++++++++------------
1 file changed, 185 insertions(+), 113 deletions(-)
diff --git a/src/qemu/qemu_domain_namespace.c b/src/qemu/qemu_domain_namespace.c
index 0c40118938..31acf2bde6 100644
--- a/src/qemu/qemu_domain_namespace.c
+++ b/src/qemu/qemu_domain_namespace.c
@@ -1098,26 +1098,58 @@ qemuDomainNamespaceAvailable(qemuDomainNamespace ns G_GNUC_UNUSED)
}
-struct qemuDomainMknodData {
- virQEMUDriverPtr driver;
- virDomainObjPtr vm;
+typedef struct _qemuDomainMknodItem qemuDomainMknodItem;
+typedef qemuDomainMknodItem *qemuDomainMknodItemPtr;
+struct _qemuDomainMknodItem {
const char *file;
char *target;
+ bool bindmounted;
GStatBuf sb;
void *acl;
-#ifdef WITH_SELINUX
char *tcon;
+};
+
+typedef struct _qemuDomainMknodData qemuDomainMknodData;
+typedef qemuDomainMknodData *qemuDomainMknodDataPtr;
+struct _qemuDomainMknodData {
+ virQEMUDriverPtr driver;
+ virDomainObjPtr vm;
+ qemuDomainMknodItemPtr items;
+ size_t nitems;
+};
+
+
+static void
+qemuDomainMknodItemClear(qemuDomainMknodItemPtr item)
+{
+ VIR_FREE(item->target);
+ virFileFreeACLs(&item->acl);
+#ifdef WITH_SELINUX
+ freecon(item->tcon);
#endif
-};
+}
+
+
+static void
+qemuDomainMknodDataClear(qemuDomainMknodDataPtr data)
+{
+ size_t i;
+
+ for (i = 0; i < data->nitems; i++) {
+ qemuDomainMknodItemPtr item = &data->items[i];
+
+ qemuDomainMknodItemClear(item);
+ }
+
+ VIR_FREE(data->items);
+}
/* Our way of creating devices is highly linux specific */
#if defined(__linux__)
static int
-qemuDomainAttachDeviceMknodHelper(pid_t pid G_GNUC_UNUSED,
- void *opaque)
+qemuDomainMknodOne(qemuDomainMknodItemPtr data)
{
- struct qemuDomainMknodData *data = opaque;
int ret = -1;
bool delDevice = false;
bool isLink = S_ISLNK(data->sb.st_mode);
@@ -1125,8 +1157,6 @@ qemuDomainAttachDeviceMknodHelper(pid_t pid G_GNUC_UNUSED,
bool isReg = S_ISREG(data->sb.st_mode) || S_ISFIFO(data->sb.st_mode) || S_ISSOCK(data->sb.st_mode);
bool isDir = S_ISDIR(data->sb.st_mode);
- qemuSecurityPostFork(data->driver->securityManager);
-
if (virFileMakeParentPath(data->file) < 0) {
virReportSystemError(errno,
_("Unable to create %s"), data->file);
@@ -1244,11 +1274,6 @@ qemuDomainAttachDeviceMknodHelper(pid_t pid G_GNUC_UNUSED,
else
unlink(data->file);
}
-# ifdef WITH_SELINUX
- freecon(data->tcon);
-# endif
- virFileFreeACLs(&data->acl);
- VIR_FREE(data->target);
return ret;
}
@@ -1265,63 +1290,66 @@ qemuDomainMknodItemIsBindMounted(mode_t st_mode)
static int
-qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver,
- virDomainObjPtr vm,
- const char *file,
- char * const *devMountsPath,
- size_t ndevMountsPath,
- unsigned int ttl)
+qemuDomainMknodHelper(pid_t pid G_GNUC_UNUSED,
+ void *opaque)
{
- g_autoptr(virQEMUDriverConfig) cfg = NULL;
- struct qemuDomainMknodData data;
+ qemuDomainMknodDataPtr data = opaque;
+ size_t i;
int ret = -1;
+
+ qemuSecurityPostFork(data->driver->securityManager);
+
+ for (i = 0; i < data->nitems; i++) {
+ if (qemuDomainMknodOne(&data->items[i]) < 0)
+ goto cleanup;
+ }
+
+ ret = 0;
+ cleanup:
+ qemuDomainMknodDataClear(data);
+ return ret;
+}
+
+
+static int
+qemuDomainMknodItemInit(qemuDomainMknodItemPtr item,
+ virQEMUDriverConfigPtr cfg,
+ virDomainObjPtr vm,
+ const char *file)
+{
g_autofree char *target = NULL;
bool isLink;
bool isReg;
- if (!ttl) {
- virReportSystemError(ELOOP,
- _("Too many levels of symbolic links: %s"),
- file);
- return ret;
- }
+ item->file = file;
- memset(&data, 0, sizeof(data));
-
- data.driver = driver;
- data.vm = vm;
- data.file = file;
-
- if (g_lstat(file, &data.sb) < 0) {
+ if (g_lstat(file, &item->sb) < 0) {
virReportSystemError(errno,
_("Unable to access %s"), file);
- return ret;
+ return -1;
}
- isLink = S_ISLNK(data.sb.st_mode);
- isReg = qemuDomainMknodItemIsBindMounted(data.sb.st_mode);
+ isLink = S_ISLNK(item->sb.st_mode);
+ isReg = qemuDomainMknodItemIsBindMounted(item->sb.st_mode);
if (isReg && STRPREFIX(file, QEMU_DEVPREFIX)) {
- cfg = virQEMUDriverGetConfig(driver);
if (!(target = qemuDomainGetPreservedMountPath(cfg, vm, file)))
- goto cleanup;
+ return -1;
- if (virFileBindMountDevice(file, target) < 0)
- goto cleanup;
-
- data.target = target;
+ item->target = g_steal_pointer(&target);
} else if (isLink) {
g_autoptr(GError) gerr = NULL;
if (!(target = g_file_read_link(file, &gerr))) {
virReportError(VIR_ERR_SYSTEM_ERROR,
_("failed to resolve symlink %s: %s"), file, gerr->message);
- return ret;
+ return -1;
}
if (!g_path_is_absolute(target)) {
g_autofree char *fileTmp = g_strdup(file);
- char *c = NULL, *tmp = NULL;
+ char *c = NULL;
+ char *tmp = NULL;
if ((c = strrchr(fileTmp, '/')))
*(c + 1) = '\0';
@@ -1331,92 +1359,79 @@ qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver,
target = g_steal_pointer(&tmp);
}
- data.target = target;
+ item->target = g_steal_pointer(&target);
}
/* Symlinks don't have ACLs. */
if (!isLink &&
- virFileGetACLs(file, &data.acl) < 0 &&
+ virFileGetACLs(file, &item->acl) < 0 &&
errno != ENOTSUP) {
virReportSystemError(errno,
_("Unable to get ACLs on %s"), file);
- goto cleanup;
+ return -1;
}
# ifdef WITH_SELINUX
- if (lgetfilecon_raw(file, &data.tcon) < 0 &&
+ if (lgetfilecon_raw(file, &item->tcon) < 0 &&
(errno != ENOTSUP && errno != ENODATA)) {
virReportSystemError(errno,
_("Unable to get SELinux label from %s"), file);
- goto cleanup;
+ return -1;
}
# endif
- if (STRPREFIX(file, QEMU_DEVPREFIX)) {
- size_t i;
-
- for (i = 0; i < ndevMountsPath; i++) {
- if (STREQ(devMountsPath[i], "/dev"))
- continue;
- if (STRPREFIX(file, devMountsPath[i]))
- break;
- }
-
- if (i == ndevMountsPath) {
- if (qemuSecurityPreFork(driver->securityManager) < 0)
- goto cleanup;
-
- if (virProcessRunInMountNamespace(vm->pid,
- qemuDomainAttachDeviceMknodHelper,
- &data) < 0) {
- qemuSecurityPostFork(driver->securityManager);
- goto cleanup;
- }
- qemuSecurityPostFork(driver->securityManager);
- } else {
- VIR_DEBUG("Skipping dev %s because of %s mount point",
- file, devMountsPath[i]);
- }
- }
-
- if (isLink &&
- qemuDomainAttachDeviceMknodRecursive(driver, vm, target,
- devMountsPath, ndevMountsPath,
- ttl -1) < 0)
- goto cleanup;
-
- ret = 0;
- cleanup:
-# ifdef WITH_SELINUX
- freecon(data.tcon);
-# endif
- virFileFreeACLs(&data.acl);
- if (isReg && target)
- umount(target);
- return ret;
+ return 0;
}
-#else /* !defined(__linux__) */
-
-
static int
-qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver G_GNUC_UNUSED,
- virDomainObjPtr vm G_GNUC_UNUSED,
- const char *file G_GNUC_UNUSED,
- char * const *devMountsPath G_GNUC_UNUSED,
- size_t ndevMountsPath G_GNUC_UNUSED,
- unsigned int ttl G_GNUC_UNUSED)
+qemuDomainAttachDeviceMknodOne(qemuDomainMknodDataPtr data,
+ virQEMUDriverConfigPtr cfg,
+ virDomainObjPtr vm,
+ const char *file,
+ char * const *devMountsPath,
+ size_t ndevMountsPath)
{
- virReportSystemError(ENOSYS, "%s",
- _("Namespaces are not supported on this platform."));
- return -1;
+ long ttl = sysconf(_SC_SYMLOOP_MAX);
+ const char *next = file;
+ size_t i;
+
+ while (1) {
+ qemuDomainMknodItem item = { 0 };
+
+ if (qemuDomainMknodItemInit(&item, cfg, vm, next) < 0)
+ return -1;
+
+ if (STRPREFIX(next, QEMU_DEVPREFIX)) {
+ for (i = 0; i < ndevMountsPath; i++) {
+ if (STREQ(devMountsPath[i], "/dev"))
+ continue;
+ if (STRPREFIX(next, devMountsPath[i]))
+ break;
+ }
+
+ if (i == ndevMountsPath &&
+ VIR_APPEND_ELEMENT_COPY(data->items, data->nitems, item) < 0)
+ return -1;
+ }
+
+ if (!S_ISLNK(item.sb.st_mode))
+ break;
+
+ if (ttl-- == 0) {
+ virReportSystemError(ELOOP,
+ _("Too many levels of symbolic links: %s"),
+ next);
+ return -1;
+ }
+
+ next = item.target;
+ }
+
+ return 0;
}
-#endif /* !defined(__linux__) */
-
-
static int
qemuDomainAttachDeviceMknod(virQEMUDriverPtr driver,
virDomainObjPtr vm,
@@ -1424,14 +1439,71 @@ qemuDomainAttachDeviceMknod(virQEMUDriverPtr driver,
char * const *devMountsPath,
size_t ndevMountsPath)
{
- long symloop_max = sysconf(_SC_SYMLOOP_MAX);
+ g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+ qemuDomainMknodData data = { 0 };
+ size_t i;
+ int ret = -1;
- return qemuDomainAttachDeviceMknodRecursive(driver, vm, file,
- devMountsPath, ndevMountsPath,
- symloop_max);
+ data.driver = driver;
+ data.vm = vm;
+
+ if (qemuDomainAttachDeviceMknodOne(&data, cfg, vm, file,
+ devMountsPath, ndevMountsPath) < 0)
+ return -1;
+
+ for (i = 0; i < data.nitems; i++) {
+ qemuDomainMknodItemPtr item = &data.items[i];
+ if (item->target &&
+ qemuDomainMknodItemIsBindMounted(item->sb.st_mode)) {
+ if (virFileBindMountDevice(item->file, item->target) < 0)
+ goto cleanup;
+ item->bindmounted = true;
+ }
+ }
+
+ if (qemuSecurityPreFork(driver->securityManager) < 0)
+ goto cleanup;
+
+ if (virProcessRunInMountNamespace(vm->pid,
+ qemuDomainMknodHelper,
+ &data) < 0) {
+ qemuSecurityPostFork(driver->securityManager);
+ goto cleanup;
+ }
+ qemuSecurityPostFork(driver->securityManager);
+
+ ret = 0;
+ cleanup:
+ for (i = 0; i < data.nitems; i++) {
+ if (data.items[i].bindmounted &&
+ umount(data.items[i].target) < 0) {
+ VIR_WARN("Unable to unmount %s", data.items[i].target);
+ }
+ }
+ qemuDomainMknodDataClear(&data);
+ return ret;
+}
+
+
+#else /* !defined(__linux__) */
+
+
+static int
+qemuDomainAttachDeviceMknod(virQEMUDriverPtr driver G_GNUC_UNUSED,
+ virDomainObjPtr vm G_GNUC_UNUSED,
+ const char *file G_GNUC_UNUSED,
+ char * const *devMountsPath G_GNUC_UNUSED,
+ size_t ndevMountsPath G_GNUC_UNUSED)
+{
+ virReportSystemError(ENOSYS, "%s",
+ _("Namespaces are not supported on this platform."));
+ return -1;
}
+#endif /* !defined(__linux__) */
+
+
static int
qemuDomainDetachDeviceUnlinkHelper(pid_t pid G_GNUC_UNUSED,
void *opaque)
--
2.26.2
More information about the libvir-list
mailing list