1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "libdm/loop_control.h"
#include <fcntl.h>
#include <linux/loop.h>
#include <stdint.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <unistd.h>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
#include "utility.h"
namespace android {
namespace dm {
LoopControl::LoopControl() : control_fd_(-1) {
control_fd_.reset(TEMP_FAILURE_RETRY(open(kLoopControlDevice, O_RDWR | O_CLOEXEC)));
if (control_fd_ < 0) {
PLOG(ERROR) << "Failed to open loop-control";
}
}
bool LoopControl::Attach(int file_fd, const std::chrono::milliseconds& timeout_ms,
std::string* loopdev) const {
auto start_time = std::chrono::steady_clock::now();
auto condition = [&]() -> WaitResult {
if (!FindFreeLoopDevice(loopdev)) {
LOG(ERROR) << "Failed to attach, no free loop devices";
return WaitResult::Fail;
}
auto now = std::chrono::steady_clock::now();
auto time_elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start_time);
if (!WaitForFile(*loopdev, timeout_ms - time_elapsed)) {
LOG(ERROR) << "Timed out waiting for path: " << *loopdev;
return WaitResult::Fail;
}
android::base::unique_fd loop_fd(
TEMP_FAILURE_RETRY(open(loopdev->c_str(), O_RDWR | O_CLOEXEC)));
if (loop_fd < 0) {
PLOG(ERROR) << "Failed to open: " << *loopdev;
return WaitResult::Fail;
}
if (int rc = ioctl(loop_fd, LOOP_SET_FD, file_fd); rc == 0) {
return WaitResult::Done;
}
if (errno != EBUSY) {
PLOG(ERROR) << "Failed LOOP_SET_FD";
return WaitResult::Fail;
}
return WaitResult::Wait;
};
if (!WaitForCondition(condition, timeout_ms)) {
LOG(ERROR) << "Timed out trying to acquire a loop device";
return false;
}
return true;
}
bool LoopControl::Detach(const std::string& loopdev) const {
if (loopdev.empty()) {
LOG(ERROR) << "Must provide a loop device";
return false;
}
android::base::unique_fd loop_fd(TEMP_FAILURE_RETRY(open(loopdev.c_str(), O_RDWR | O_CLOEXEC)));
if (loop_fd < 0) {
PLOG(ERROR) << "Failed to open: " << loopdev;
return false;
}
int rc = ioctl(loop_fd, LOOP_CLR_FD, 0);
if (rc) {
PLOG(ERROR) << "Failed LOOP_CLR_FD for '" << loopdev << "'";
return false;
}
return true;
}
bool LoopControl::FindFreeLoopDevice(std::string* loopdev) const {
int rc = ioctl(control_fd_, LOOP_CTL_GET_FREE);
if (rc < 0) {
PLOG(ERROR) << "Failed to get free loop device";
return false;
}
// Ueventd on android creates all loop devices as /dev/block/loopX
// The total number of available devices is determined by 'loop.max_part'
// kernel command line argument.
*loopdev = ::android::base::StringPrintf("/dev/block/loop%d", rc);
return true;
}
bool LoopControl::EnableDirectIo(int fd) {
#if !defined(LOOP_SET_BLOCK_SIZE)
static constexpr int LOOP_SET_BLOCK_SIZE = 0x4C09;
#endif
#if !defined(LOOP_SET_DIRECT_IO)
static constexpr int LOOP_SET_DIRECT_IO = 0x4C08;
#endif
// Note: the block size has to be >= the logical block size of the underlying
// block device, *not* the filesystem block size.
if (ioctl(fd, LOOP_SET_BLOCK_SIZE, 4096)) {
PLOG(ERROR) << "Could not set loop device block size";
return false;
}
if (ioctl(fd, LOOP_SET_DIRECT_IO, 1)) {
PLOG(ERROR) << "Could not set loop direct IO";
return false;
}
return true;
}
bool LoopControl::SetAutoClearStatus(int fd) {
struct loop_info64 info = {};
info.lo_flags |= LO_FLAGS_AUTOCLEAR;
if (ioctl(fd, LOOP_SET_STATUS64, &info)) {
return false;
}
return true;
}
LoopDevice::LoopDevice(android::base::borrowed_fd fd, const std::chrono::milliseconds& timeout_ms,
bool auto_close)
: fd_(fd), owned_fd_(-1) {
if (auto_close) {
owned_fd_.reset(fd.get());
}
Init(timeout_ms);
}
LoopDevice::LoopDevice(const std::string& path, const std::chrono::milliseconds& timeout_ms)
: fd_(-1), owned_fd_(-1) {
owned_fd_.reset(open(path.c_str(), O_RDWR | O_CLOEXEC));
if (owned_fd_ == -1) {
PLOG(ERROR) << "open failed for " << path;
return;
}
fd_ = owned_fd_;
Init(timeout_ms);
}
LoopDevice::~LoopDevice() {
if (valid()) {
control_.Detach(device_);
}
}
void LoopDevice::Init(const std::chrono::milliseconds& timeout_ms) {
valid_ = control_.Attach(fd_.get(), timeout_ms, &device_);
}
} // namespace dm
} // namespace android
|
