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Merge "COW device initialized by zeroing the whole first chunk"

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Treehugger Robot 2019-10-31 11:19:56 +00:00 committed by Gerrit Code Review
commit e88b568442
1 changed files with 6 additions and 7 deletions
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13
fs_mgr/libsnapshot/utility.cpp
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@ -19,6 +19,7 @@
#include <android-base/strings.h>
#include <fs_mgr/roots.h>
using android::dm::kSectorSize;
using android::fs_mgr::EnsurePathMounted;
using android::fs_mgr::EnsurePathUnmounted;
using android::fs_mgr::Fstab;
@ -94,13 +95,11 @@ bool InitializeCow(const std::string& device) {
// so it can be used to resume the last state of a snapshot device;
// - an _INVALID_ snapshot otherwise.
// To avoid zero-filling the whole CoW file when a new dm-snapshot is
// created, here we zero-fill only the first 32 bits. This is a temporary
// workaround that will be discussed again when the kernel API gets
// consolidated.
// TODO(b/139202197): Remove this hack once the kernel API is consolidated.
constexpr ssize_t kDmSnapZeroFillSize = 4; // 32-bit
// created, here we zero-fill only the first chunk to be compliant with
// lvm.
constexpr ssize_t kDmSnapZeroFillSize = kSectorSize * kSnapshotChunkSize;
char zeros[kDmSnapZeroFillSize] = {0};
std::vector<uint8_t> zeros(kDmSnapZeroFillSize, 0);
android::base::unique_fd fd(open(device.c_str(), O_WRONLY | O_BINARY));
if (fd < 0) {
PLOG(ERROR) << "Can't open COW device: " << device;
@ -108,7 +107,7 @@ bool InitializeCow(const std::string& device) {
}
LOG(INFO) << "Zero-filling COW device: " << device;
if (!android::base::WriteFully(fd, zeros, kDmSnapZeroFillSize)) {
if (!android::base::WriteFully(fd, zeros.data(), kDmSnapZeroFillSize)) {
PLOG(ERROR) << "Can't zero-fill COW device for " << device;
return false;
}