init: automatically add a new loop device when there are no idle loop devices
Signed-off-by: tangjie1 <tangjie1@xiaomi.com>
Change-Id: I5fe6df9b733c4932334097aff6b7781dcb34027e
diff --git a/init/builtins.cpp b/init/builtins.cpp
index bc23972..585eca2 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -60,6 +60,8 @@
#include <cutils/android_reboot.h>
#include <fs_mgr.h>
#include <fscrypt/fscrypt.h>
+#include <libdm/dm.h>
+#include <libdm/loop_control.h>
#include <libgsi/libgsi.h>
#include <logwrap/logwrap.h>
#include <private/android_filesystem_config.h>
@@ -506,29 +508,29 @@
if (android::base::StartsWith(source, "loop@")) {
int mode = (flags & MS_RDONLY) ? O_RDONLY : O_RDWR;
- unique_fd fd(TEMP_FAILURE_RETRY(open(source + 5, mode | O_CLOEXEC)));
- if (fd < 0) return ErrnoError() << "open(" << source + 5 << ", " << mode << ") failed";
+ const char* file_path = source + strlen("loop@");
- for (size_t n = 0;; n++) {
- std::string tmp = android::base::StringPrintf("/dev/block/loop%zu", n);
- unique_fd loop(TEMP_FAILURE_RETRY(open(tmp.c_str(), mode | O_CLOEXEC)));
- if (loop < 0) return ErrnoError() << "open(" << tmp << ", " << mode << ") failed";
-
- loop_info info;
- /* if it is a blank loop device */
- if (ioctl(loop.get(), LOOP_GET_STATUS, &info) < 0 && errno == ENXIO) {
- /* if it becomes our loop device */
- if (ioctl(loop.get(), LOOP_SET_FD, fd.get()) >= 0) {
- if (mount(tmp.c_str(), target, system, flags, options) < 0) {
- ioctl(loop.get(), LOOP_CLR_FD, 0);
- return ErrnoError() << "mount() failed";
- }
- return {};
- }
- }
+ // Open source file
+ if (wait) {
+ wait_for_file(file_path, kCommandRetryTimeout);
}
- return Error() << "out of loopback devices";
+ unique_fd fd(TEMP_FAILURE_RETRY(open(file_path, mode | O_CLOEXEC)));
+ if (fd < 0) {
+ return ErrnoError() << "open(" << file_path << ", " << mode << ") failed";
+ }
+
+ // Allocate loop device and attach it to file_path.
+ android::dm::LoopControl loop_control;
+ std::string loop_device;
+ if (!loop_control.Attach(fd.get(), 5s, &loop_device)) {
+ return ErrnoError() << "loop_control.Attach " << file_path << " failed";
+ }
+
+ if (mount(loop_device.c_str(), target, system, flags, options) < 0) {
+ loop_control.Detach(loop_device);
+ return ErrnoError() << "mount() failed";
+ }
} else {
if (wait)
wait_for_file(source, kCommandRetryTimeout);