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fs_mgr_get_mounted_entry_for_userdata: handle logical partitions

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In case of GSI on DSU, /data is mounted on the following stack:
userdata -> userdata_gsi -> actual block device, and fstab returned from
ReadDefaultFstab() function will say that /data should be
mounted onto userdata_gsi. This configuration wasn't supported.

To support it, fs_mgr_get_mounted_entry_for_userdata now unwinds the
dm-device stack /data is mounted onto, and for each entry in fstab
resolves corresponding block device (in case of logical partitions by
asking DeviceMapper to resolve name -> path, and for other cases by
reading a symlink), and then checking whenever resolved block device
belongs to the unwinded stack.

Test: on both normal boot & DSU
Test: atest CtsUserspaceRebootHostSideTestCases
Test: atest CtsFsMgrTestCases
Bug: 148612148
Change-Id: I1bb3e64ae92d56de905b4f7f1997b7499b101b0f
Merged-In: I1bb3e64ae92d56de905b4f7f1997b7499b101b0f
(cherry picked from commit f495fe798b)
This commit is contained in:
Nikita Ioffe 2020-03-06 17:36:05 +00:00
parent f1e27502e4
commit 17824f0590
1 changed files with 30 additions and 48 deletions
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78
fs_mgr/fs_mgr.cpp
View file

@ -1588,76 +1588,58 @@ static bool fs_mgr_unmount_all_data_mounts(const std::string& block_device) {
}
}
static std::string ResolveBlockDevice(const std::string& block_device) {
static bool UnwindDmDeviceStack(const std::string& block_device,
std::vector<std::string>* dm_stack) {
if (!StartsWith(block_device, "/dev/block/")) {
LWARNING << block_device << " is not a block device";
return block_device;
return false;
}
std::string name = block_device.substr(5);
if (!StartsWith(name, "block/dm-")) {
// Not a dm-device, but might be a symlink. Optimistically try to readlink.
std::string result;
if (Readlink(block_device, &result)) {
return result;
} else if (errno == EINVAL) {
// After all, it wasn't a symlink.
return block_device;
} else {
LERROR << "Failed to readlink " << block_device;
return "";
}
}
// It's a dm-device, let's find what's inside!
std::string sys_dir = "/sys/" + name;
std::string current = block_device;
DeviceMapper& dm = DeviceMapper::Instance();
while (true) {
std::string slaves_dir = sys_dir + "/slaves";
std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(slaves_dir.c_str()), closedir);
if (!dir) {
LERROR << "Failed to open " << slaves_dir;
return "";
dm_stack->push_back(current);
if (!dm.IsDmBlockDevice(current)) {
break;
}
std::string sub_device_name = "";
for (auto entry = readdir(dir.get()); entry; entry = readdir(dir.get())) {
if (entry->d_type != DT_LNK) continue;
if (!sub_device_name.empty()) {
LERROR << "Too many slaves in " << slaves_dir;
return "";
}
sub_device_name = entry->d_name;
auto parent = dm.GetParentBlockDeviceByPath(current);
if (!parent) {
return false;
}
if (sub_device_name.empty()) {
LERROR << "No slaves in " << slaves_dir;
return "";
}
if (!StartsWith(sub_device_name, "dm-")) {
// Not a dm-device! We can stop now.
return "/dev/block/" + sub_device_name;
}
// Still a dm-device, keep digging.
sys_dir = "/sys/block/" + sub_device_name;
current = *parent;
}
return true;
}
FstabEntry* fs_mgr_get_mounted_entry_for_userdata(Fstab* fstab, const FstabEntry& mounted_entry) {
std::string resolved_block_device = ResolveBlockDevice(mounted_entry.blk_device);
if (resolved_block_device.empty()) {
if (mounted_entry.mount_point != "/data") {
LERROR << mounted_entry.mount_point << " is not /data";
return nullptr;
}
std::vector<std::string> dm_stack;
if (!UnwindDmDeviceStack(mounted_entry.blk_device, &dm_stack)) {
LERROR << "Failed to unwind dm-device stack for " << mounted_entry.blk_device;
return nullptr;
}
LINFO << "/data is mounted on " << resolved_block_device;
for (auto& entry : *fstab) {
if (entry.mount_point != "/data") {
continue;
}
std::string block_device;
if (!Readlink(entry.blk_device, &block_device)) {
LWARNING << "Failed to readlink " << entry.blk_device;
if (entry.fs_mgr_flags.logical) {
if (!fs_mgr_update_logical_partition(&entry)) {
LERROR << "Failed to update logic partition " << entry.blk_device;
continue;
}
block_device = entry.blk_device;
} else if (!Readlink(entry.blk_device, &block_device)) {
PWARNING << "Failed to read link " << entry.blk_device;
block_device = entry.blk_device;
}
if (block_device == resolved_block_device) {
if (std::find(dm_stack.begin(), dm_stack.end(), block_device) != dm_stack.end()) {
return &entry;
}
}
LERROR << "Didn't find entry that was used to mount /data";
LERROR << "Didn't find entry that was used to mount /data onto " << mounted_entry.blk_device;
return nullptr;
}