[EROFS] Align with the block size of overlayBD

The inconsistency in the default block sizes between OverlayBD
and EROFS can lead to issues during segment mapping. This patch
aligns with the block size of overlaybd for mapping (i.e.,
OverlayBD's 512-byte size) to overcome this inconsistency.

Signed-off-by: Hongzhen Luo <[email protected]>

Author: Hongzhen Luo

src/overlaybd/tar/erofs/CMakeLists.txt

@@ -3,7 +3,7 @@ include(FetchContent)
 FetchContent_Declare(
     erofs-utils
     GIT_REPOSITORY https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git
-    GIT_TAG        ac0997ea32a465a6b0db7b782bb8d4d07952365a
+    GIT_TAG        654e8b8a8f1a87b0746ff47db00dec1afc05fbc9
 )
 
 FetchContent_MakeAvailable(erofs-utils)

src/overlaybd/tar/erofs/liberofs.cpp

@@ -580,25 +580,38 @@ static int erofs_init_tar(struct erofs_tarfile *erofstar,
 static int erofs_write_map_file(photon::fs::IFile *fout, uint64_t blksz, FILE *fp)
 {
     uint64_t blkaddr, toff;
-    uint32_t nblocks;
+    uint32_t nblocks, zeroedlen;
+    char *line = NULL;
+    size_t len  = 0;
+    int cnt;
 
     if (fp == NULL) {
        LOG_ERROR("unable to get upper.map, ignored");
        return -1;
     }
     rewind(fp);
-    while (fscanf(fp, "%" PRIx64" %x %" PRIx64 "\n", &blkaddr, &nblocks, &toff)
-           >= 3)
-    {
+
+    while (getline(&line, &len, fp) != -1) {
         LSMT::RemoteMapping lba;
+
+        cnt = sscanf(line, "%" PRIx64" %x%" PRIx64 "%u", &blkaddr, &nblocks, &toff, &zeroedlen);
+        if (cnt < 3) {
+            LOG_ERROR("Bad formatted map file.");
+            break;
+        }
+
         lba.offset = blkaddr * blksz;
         lba.count = nblocks * blksz;
         lba.roffset = toff;
+        if (cnt > 3)
+            lba.count = round_up_blk(lba.count - zeroedlen);
+
         int nwrite = fout->ioctl(LSMT::IFileRW::RemoteData, lba);
         if ((unsigned) nwrite != lba.count) {
             LOG_ERRNO_RETURN(0, -1, "failed to write lba");
         }
     }
+    free(line);
 
     return 0;
 }