commit 51f36da47a3e8fb6d7b285742aa91e6d2a48f6e1
author David Anderson <dvander@google.com> Mon Nov 01 22:55:45 2021 +0000
committer Gerrit Code Review <noreply-gerritcodereview@google.com> Mon Nov 01 22:55:45 2021 +0000
tree e544b20580deb7d2f8436536cc2c86ce7841bda4
parent a86af7c9b156877850e354ac85912de717a8e808
parent de2ec0b4277e18daa00ecbd94125064b8b0b781f

Merge "libfiemap: Only call FS_IOC_FIEMAP once."

fs_mgr/libfiemap/fiemap_writer.cpp

diff --git a/fs_mgr/libfiemap/fiemap_writer.cpp b/fs_mgr/libfiemap/fiemap_writer.cpp
index 8acb885..71dadd0 100644
--- a/fs_mgr/libfiemap/fiemap_writer.cpp
+++ b/fs_mgr/libfiemap/fiemap_writer.cpp
@@ -498,24 +498,6 @@
     return IsFilePinned(fd, file_path, sfs.f_type);
 }
 
-static bool CountFiemapExtents(int file_fd, const std::string& file_path, uint32_t* num_extents) {
-    struct fiemap fiemap = {};
-    fiemap.fm_start = 0;
-    fiemap.fm_length = UINT64_MAX;
-    fiemap.fm_flags = FIEMAP_FLAG_SYNC;
-    fiemap.fm_extent_count = 0;
-
-    if (ioctl(file_fd, FS_IOC_FIEMAP, &fiemap)) {
-        PLOG(ERROR) << "Failed to get FIEMAP from the kernel for file: " << file_path;
-        return false;
-    }
-
-    if (num_extents) {
-        *num_extents = fiemap.fm_mapped_extents;
-    }
-    return true;
-}
-
 static bool IsValidExtent(const fiemap_extent* extent, std::string_view file_path) {
     if (extent->fe_flags & kUnsupportedExtentFlags) {
         LOG(ERROR) << "Extent at location " << extent->fe_logical << " of file " << file_path
@@ -530,12 +512,12 @@
 }
 
 static bool FiemapToExtents(struct fiemap* fiemap, std::vector<struct fiemap_extent>* extents,
-                            uint32_t num_extents, std::string_view file_path) {
-    if (num_extents == 0) return false;
-
+                            std::string_view file_path) {
+    uint32_t num_extents = fiemap->fm_mapped_extents;
     const struct fiemap_extent* last_extent = &fiemap->fm_extents[num_extents - 1];
     if (!IsLastExtent(last_extent)) {
-        LOG(ERROR) << "FIEMAP did not return a final extent for file: " << file_path;
+        LOG(ERROR) << "FIEMAP did not return a final extent for file: " << file_path
+                   << " num_extents=" << num_extents << " max_extents=" << kMaxExtents;
         return false;
     }
 
@@ -577,21 +559,7 @@
 
 static bool ReadFiemap(int file_fd, const std::string& file_path,
                        std::vector<struct fiemap_extent>* extents) {
-    uint32_t num_extents;
-    if (!CountFiemapExtents(file_fd, file_path, &num_extents)) {
-        return false;
-    }
-    if (num_extents == 0) {
-        LOG(ERROR) << "File " << file_path << " has zero extents";
-        return false;
-    }
-    if (num_extents > kMaxExtents) {
-        LOG(ERROR) << "File has " << num_extents << ", maximum is " << kMaxExtents << ": "
-                   << file_path;
-        return false;
-    }
-
-    uint64_t fiemap_size = sizeof(struct fiemap) + num_extents * sizeof(struct fiemap_extent);
+    uint64_t fiemap_size = sizeof(struct fiemap) + kMaxExtents * sizeof(struct fiemap_extent);
     auto buffer = std::unique_ptr<void, decltype(&free)>(calloc(1, fiemap_size), free);
     if (buffer == nullptr) {
         LOG(ERROR) << "Failed to allocate memory for fiemap";
@@ -603,19 +571,13 @@
     fiemap->fm_length = UINT64_MAX;
     // make sure file is synced to disk before we read the fiemap
     fiemap->fm_flags = FIEMAP_FLAG_SYNC;
-    fiemap->fm_extent_count = num_extents;
+    fiemap->fm_extent_count = kMaxExtents;
 
     if (ioctl(file_fd, FS_IOC_FIEMAP, fiemap)) {
         PLOG(ERROR) << "Failed to get FIEMAP from the kernel for file: " << file_path;
         return false;
     }
-    if (fiemap->fm_mapped_extents != num_extents) {
-        LOG(ERROR) << "FIEMAP returned unexpected extent count (" << num_extents
-                   << " expected, got " << fiemap->fm_mapped_extents << ") for file: " << file_path;
-        return false;
-    }
-
-    return FiemapToExtents(fiemap, extents, num_extents, file_path);
+    return FiemapToExtents(fiemap, extents, file_path);
 }
 
 static bool ReadFibmap(int file_fd, const std::string& file_path,