How to test new file system types

1. create new file sytem types image on host, like
    dd if=/dev/zero of=nilfs.img bs=1M count=1024
    mkfs.nilfs2 nilfs.img

2. push this image file into device
    adb push nilfs.img /data/local/tmp

3. on device side, try to mount it
    losetup /dev/block/loop7 nilfs.img
    mount -t nilfs2 /dev/block/loop7 nilfs

   if it's failed to mount that file system type,
   then you need to check the kernel side to make the mount supported
   like add following kernel config:
    CONFIG_NILFS2_FS=y

4. edit fstab to enabled mount with new types for boot
   since entries in fstab.xxx will be tried till the first line that partition
   is mounted successfully, so we can write multiple lines for the same
   partition there with different file system types and mount options
   like:
       /dev/block/platform/soc/f723d000.dwmmc0/by-name/userdata    /data               nilfs2    defaults    wait

5. since selinux is enabled by default, and we probably will have selinux
   problem with the new file system type.
   TODO: details on selinux enabling for new file system type

   add "androidboot.selinux=permissive" to the boot parameters to use permissive mode


    patch on external/libselinux:
    
    diff --git a/src/android.c b/src/android.c
index 5206a9f..fbab7e8 100644
--- a/src/android.c
+++ b/src/android.c
@@ -869,8 +869,11 @@ int selinux_android_setfilecon(const char *pkgdir,
 
 	if (strcmp(ctx_str, orig_ctx_str)) {
 		rc = setfilecon(pkgdir, ctx_str);
-		if (rc < 0)
-			goto err;
+		if (rc < 0) {
+            if (security_getenforce()){
+			    goto err;
+            }
+        }
 	}
 
 	rc = 0;
@@ -1253,8 +1256,11 @@ static int restorecon_sb(const char *pathname, const struct stat *sb,
             selinux_log(SELINUX_INFO,
                         "SELinux:  Relabeling %s from %s to %s.\n", pathname, oldsecontext, secontext);
         if (!nochange) {
-            if (lsetfilecon(pathname, secontext) < 0)
-                goto err;
+            if (lsetfilecon(pathname, secontext) < 0) {
+                if (security_getenforce()){
+                    goto err;
+                }
+            }
         }
     }
 
    
4. get raw type image file, and see if the device could boot up with the new file sytem type

   since file system image file flashing needs to be the same size as the device,
   so it would be better to use the original generated work image files.

   Like for the userdata partition:
   1). get the raw userdata image file:
       sepcified TARGET_USERIMAGES_SPARSE_EXT_DISABLED to true before
       start building will generate the raw type userdata image file
   2). use simg2img command
       ./out/host/linux-x86/bin/simg2img out/target/product/hikey/userdata.img out/target/product/hikey/userdata-raw.img

5. format the raw image file with new file system type for userdata partition
    mkfs.nilfs2 out/target/product/hikey/userdata-raw.img

   This is only for experiment. For real product, the userdata.img or system.img
   should have prebuilt files in it, and have permission, selinux settings set.

8. generate sparse image file for the new file system type image file
   1) use img2simg
   out/host/linux-x86/bin/img2simg out/target/product/hikey/userdata-raw.img out/target/product/hikey/userdata-nilfs.img

   2) since hikey fastboot does not support FILL type chunk in the sparse image file,
   so we need to add the following patch

        12:22:27 liuyq: core$ git diff
        diff --git a/libsparse/backed_block.c b/libsparse/backed_block.c
        index 794cd6b..ecf7d6b 100644
        --- a/libsparse/backed_block.c
        +++ b/libsparse/backed_block.c
        @@ -25,7 +25,7 @@
         
         struct backed_block {
                unsigned int block;
        -       unsigned int len;
        +       int64_t len;
                enum backed_block_type type;
                union {
                        struct {
        diff --git a/libsparse/sparse_read.c b/libsparse/sparse_read.c
        index dbb4dab..c00a686 100644
        --- a/libsparse/sparse_read.c
        +++ b/libsparse/sparse_read.c
        @@ -363,7 +363,7 @@ static int sparse_file_read_normal(struct sparse_file *s, int fd)
                int64_t offset = 0;
                unsigned int to_read;
                unsigned int i;
        -       bool sparse_block;
        +       bool sparse_block = false;
         
                if (!buf) {
                        return -ENOMEM;
        @@ -377,7 +377,7 @@ static int sparse_file_read_normal(struct sparse_file *s, int fd)
                                free(buf);
                                return ret;
                        }
        -
        +/*
                        if (to_read == s->block_size) {
                                sparse_block = true;
                                for (i = 1; i < s->block_size / sizeof(uint32_t); i++) {
        @@ -386,9 +386,9 @@ static int sparse_file_read_normal(struct sparse_file *s, int fd)
                                                break;
                                        }
                                }
        -               } else {
        +               } else { */
                                sparse_block = false;
        -               }
        +       /*      }*/
         
                        if (sparse_block) {
                                /* TODO: add flag to use skip instead of fill for buf[0] == 0 */
        12:22:29 liuyq: core$