ubi: fastmap: Allocate memory with GFP_NOFS in ubi_update_fastmap
Function ubi_update_fastmap could be called in IO context, for example:
ubifs_writepage
do_writepage
ubifs_jnl_write_data
write_head
ubifs_wbuf_write_nolock
ubifs_leb_write
ubi_leb_write
ubi_eba_write_leb
try_write_vid_and_data
ubi_wl_get_peb
ubi_update_fastmap
erase_block
So it's better to allocate memory with GFP_NOFS mode, in case waiting
page writeback(dead loop).
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Signed-off-by: Richard Weinberger <richard@nod.at>