[PATCH RESEND] f2fs: move bio_private allocation out of f2fs_bio_alloc()

bio->bi_private is not always needed. As in the reading data path, end_read_io does not need bio_private for further using, so moving bio_private allocation out of f2fs_bio_alloc(). Alloc it in the submit_write_page(), and ignore it in the f2fs_readpage(). Signed-off-by: Gu Zheng ---

[PATCH RESEND] f2fs: move bio_private allocation out of f2fs_bio_alloc()

bio-bi_private is not always needed. As in the reading data path, end_read_io does not need bio_private for further using, so moving bio_private allocation out of f2fs_bio_alloc(). Alloc it in the submit_write_page(), and ignore it in the f2fs_readpage(). Signed-off-by: Gu Zheng