e2fsprogs: properly set up extent header in do_write
do_write doesn't fully set up the first extent header on a new
inode, so if we write a 0-length file, and don't write any data
to the new file, we end up creating something that looks corrupt
to kernelspace:
EXT4-fs error (device loop0): ext4_ext_check_inode:464: inode #12: comm
ls: bad header/extent: invalid magic - magic 0, entries 0, max 0(0),
depth 0(0)
Do something similar to ext4_ext_tree_init() here, and
fill out the first extent header upon creation to avoid this.
[YOCTO #3848]
Signed-off-by: Robert Yang <liezhi.yang@windriver.com> Signed-off-by: Saul Wold <sgw@linux.intel.com>
