libfiemap: Fix fallocate() usage.
This fixes two bugs in how we use fallocate(). First, using ZERO_RANGE
is a mechanism to allocate holes, not blocks. Instead we should be
passing no flags.
The reason this code worked is because of our explicit writes to the
file, which is intended to defeat lazy block allocation. This is not
necessary for F2FS with proper file pinning support, so we now skip this
when possible.
Together, these fixes improve the speed of "adb remount" when backed
by libfiemap.
Bug: 134949511
Test: adb remount when backed by /data
Change-Id: I746053d183e0c83d56979d9c3fa6d96b40b5e478
diff --git a/fs_mgr/libfiemap/fiemap_writer.cpp b/fs_mgr/libfiemap/fiemap_writer.cpp
index 961533e..b5794d3 100644
--- a/fs_mgr/libfiemap/fiemap_writer.cpp
+++ b/fs_mgr/libfiemap/fiemap_writer.cpp
@@ -386,43 +386,12 @@
return true;
}
-// Reserve space for the file on the file system and write it out to make sure the extents
-// don't come back unwritten. Return from this function with the kernel file offset set to 0.
-// If the filesystem is f2fs, then we also PIN the file on disk to make sure the blocks
-// aren't moved around.
-static bool AllocateFile(int file_fd, const std::string& file_path, uint64_t blocksz,
- uint64_t file_size, unsigned int fs_type,
- std::function<bool(uint64_t, uint64_t)> on_progress) {
- switch (fs_type) {
- case EXT4_SUPER_MAGIC:
- break;
- case F2FS_SUPER_MAGIC: {
- bool supported;
- if (!F2fsPinBeforeAllocate(file_fd, &supported)) {
- return false;
- }
- if (supported && !PinFile(file_fd, file_path, fs_type)) {
- return false;
- }
- break;
- }
- case MSDOS_SUPER_MAGIC:
- // fallocate() is not supported, and not needed, since VFAT does not support holes.
- // Instead we can perform a much faster allocation.
- return FallocateFallback(file_fd, blocksz, file_size, file_path, on_progress);
- default:
- LOG(ERROR) << "Missing fallocate() support for file system " << fs_type;
- return false;
- }
-
- if (fallocate(file_fd, FALLOC_FL_ZERO_RANGE, 0, file_size)) {
- PLOG(ERROR) << "Failed to allocate space for file: " << file_path << " size: " << file_size;
- return false;
- }
-
- // write zeroes in 'blocksz' byte increments until we reach file_size to make sure the data
- // blocks are actually written to by the file system and thus getting rid of the holes in the
- // file.
+// write zeroes in 'blocksz' byte increments until we reach file_size to make sure the data
+// blocks are actually written to by the file system and thus getting rid of the holes in the
+// file.
+static bool WriteZeroes(int file_fd, const std::string& file_path, size_t blocksz,
+ uint64_t file_size,
+ const std::function<bool(uint64_t, uint64_t)>& on_progress) {
auto buffer = std::unique_ptr<void, decltype(&free)>(calloc(1, blocksz), free);
if (buffer == nullptr) {
LOG(ERROR) << "failed to allocate memory for writing file";
@@ -460,6 +429,50 @@
PLOG(ERROR) << "Failed to reset offset at the beginning of : " << file_path;
return false;
}
+ return true;
+}
+
+// Reserve space for the file on the file system and write it out to make sure the extents
+// don't come back unwritten. Return from this function with the kernel file offset set to 0.
+// If the filesystem is f2fs, then we also PIN the file on disk to make sure the blocks
+// aren't moved around.
+static bool AllocateFile(int file_fd, const std::string& file_path, uint64_t blocksz,
+ uint64_t file_size, unsigned int fs_type,
+ std::function<bool(uint64_t, uint64_t)> on_progress) {
+ bool need_explicit_writes = true;
+ switch (fs_type) {
+ case EXT4_SUPER_MAGIC:
+ break;
+ case F2FS_SUPER_MAGIC: {
+ bool supported;
+ if (!F2fsPinBeforeAllocate(file_fd, &supported)) {
+ return false;
+ }
+ if (supported) {
+ if (!PinFile(file_fd, file_path, fs_type)) {
+ return false;
+ }
+ need_explicit_writes = false;
+ }
+ break;
+ }
+ case MSDOS_SUPER_MAGIC:
+ // fallocate() is not supported, and not needed, since VFAT does not support holes.
+ // Instead we can perform a much faster allocation.
+ return FallocateFallback(file_fd, blocksz, file_size, file_path, on_progress);
+ default:
+ LOG(ERROR) << "Missing fallocate() support for file system " << fs_type;
+ return false;
+ }
+
+ if (fallocate(file_fd, 0, 0, file_size)) {
+ PLOG(ERROR) << "Failed to allocate space for file: " << file_path << " size: " << file_size;
+ return false;
+ }
+
+ if (need_explicit_writes && !WriteZeroes(file_fd, file_path, blocksz, file_size, on_progress)) {
+ return false;
+ }
// flush all writes here ..
if (fsync(file_fd)) {