fs:ext4:write:fix: Reinitialize global variables after updating a file
This bug shows up when file stored on the ext4 file system is updated.
The ext4fs_delete_file() is responsible for deleting file's (e.g. uImage)
data.
However some global data (especially ext4fs_indir2_block), which is used
during file deletion are left unchanged.
The ext4fs_indir2_block pointer stores reference to old ext4 double
indirect allocated blocks. When it is unchanged, after file deletion,
ext4fs_write_file() uses the same pointer (since it is already initialized
- i.e. not NULL) to return number of blocks to write. This trunks larger
file when previous one was smaller.
Lets consider following scenario:
1. Flash target with ext4 formatted boot.img (which has uImage [*] on itself)
2. Developer wants to upload their custom uImage [**]
- When new uImage [**] is smaller than the [*] - everything works
correctly - we are able to store the whole smaller file with corrupted
ext4fs_indir2_block pointer
- When new uImage [**] is larger than the [*] - theCRC is corrupted,
since truncation on data stored at eMMC was done.
3. When uImage CRC error appears, then reboot and LTHOR/DFU reflashing causes
proper setting of ext4fs_indir2_block() and after that uImage[**]
is successfully stored (correct uImage [*] metadata is stored at an
eMMC on the first flashing).
Due to above the bug was very difficult to reproduce.
This patch sets default values for all ext4fs_indir* pointers/variables.
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index 62e2e80..1c11721 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -1841,16 +1841,20 @@
return blknr;
}
-void ext4fs_close(void)
+/**
+ * ext4fs_reinit_global() - Reinitialize values of ext4 write implementation's
+ * global pointers
+ *
+ * This function assures that for a file with the same name but different size
+ * the sequential store on the ext4 filesystem will be correct.
+ *
+ * In this function the global data, responsible for internal representation
+ * of the ext4 data are initialized to the reset state. Without this, during
+ * replacement of the smaller file with the bigger truncation of new file was
+ * performed.
+ */
+void ext4fs_reinit_global(void)
{
- if ((ext4fs_file != NULL) && (ext4fs_root != NULL)) {
- ext4fs_free_node(ext4fs_file, &ext4fs_root->diropen);
- ext4fs_file = NULL;
- }
- if (ext4fs_root != NULL) {
- free(ext4fs_root);
- ext4fs_root = NULL;
- }
if (ext4fs_indir1_block != NULL) {
free(ext4fs_indir1_block);
ext4fs_indir1_block = NULL;
@@ -1869,6 +1873,19 @@
ext4fs_indir3_size = 0;
ext4fs_indir3_blkno = -1;
}
+}
+void ext4fs_close(void)
+{
+ if ((ext4fs_file != NULL) && (ext4fs_root != NULL)) {
+ ext4fs_free_node(ext4fs_file, &ext4fs_root->diropen);
+ ext4fs_file = NULL;
+ }
+ if (ext4fs_root != NULL) {
+ free(ext4fs_root);
+ ext4fs_root = NULL;
+ }
+
+ ext4fs_reinit_global();
}
int ext4fs_iterate_dir(struct ext2fs_node *dir, char *name,
diff --git a/fs/ext4/ext4_write.c b/fs/ext4/ext4_write.c
index 3db22f8..c42add9 100644
--- a/fs/ext4/ext4_write.c
+++ b/fs/ext4/ext4_write.c
@@ -562,6 +562,7 @@
ext4fs_update();
ext4fs_deinit();
+ ext4fs_reinit_global();
if (ext4fs_init() != 0) {
printf("error in File System init\n");