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init: automatically add a new loop device when there are no idle loop devices

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Signed-off-by: tangjie1 <tangjie1@xiaomi.com>
Change-Id: I5fe6df9b733c4932334097aff6b7781dcb34027e
This commit is contained in:
tangjie1 2023-04-13 17:15:23 +08:00
parent 82c4ce215b
commit 2b26bdf973
1 changed files with 22 additions and 20 deletions
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42
init/builtins.cpp
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@ -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 @@ static Result<void> do_mount(const BuiltinArguments& args) {
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);