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Block and wait for /dev/block/loop<N> to appear in case it was created asynchronously.

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Bug: 134711825
Bug: 149462396
Test: StorageManagerTest
Change-Id: Id8616804bba622226ca21b8eff0d3eb577b4b7e0
Merged-In: Id8616804bba622226ca21b8eff0d3eb577b4b7e0
This commit is contained in:
David Anderson 2019-06-11 14:51:25 -07:00 committed by Martijn Coenen
parent 1b535e41fd
commit 5ba8aeaa80
1 changed files with 26 additions and 0 deletions
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26
Loop.cpp
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@ -31,6 +31,9 @@
#include <linux/kdev_t.h>
#include <chrono>
#include <thread>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
@ -41,12 +44,29 @@
#include "VoldUtil.h"
#include "sehandle.h"
using namespace std::literals;
using android::base::StringPrintf;
using android::base::unique_fd;
static const char* kVoldPrefix = "vold:";
static constexpr size_t kLoopDeviceRetryAttempts = 3u;
static bool wait_for_file(const std::string& filename,
const std::chrono::milliseconds relative_timeout) {
auto start_time = std::chrono::steady_clock::now();
while (true) {
int rv = access(filename.c_str(), F_OK);
if (!rv || errno != ENOENT) return true;
std::this_thread::sleep_for(50ms);
auto now = std::chrono::steady_clock::now();
auto time_elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start_time);
if (time_elapsed > relative_timeout) return false;
}
}
int Loop::create(const std::string& target, std::string& out_device) {
unique_fd ctl_fd(open("/dev/loop-control", O_RDWR | O_CLOEXEC));
if (ctl_fd.get() == -1) {
@ -74,6 +94,12 @@ int Loop::create(const std::string& target, std::string& out_device) {
PLOG(ERROR) << "Failed to open " << target;
return -errno;
}
if (!wait_for_file(out_device, 2s)) {
LOG(ERROR) << "Failed to find " << out_device;
return -ENOENT;
}
unique_fd device_fd(open(out_device.c_str(), O_RDWR | O_CLOEXEC));
if (device_fd.get() == -1) {
PLOG(ERROR) << "Failed to open " << out_device;