On Tue 17-04-18 19:50:23, Darrick J. Wong wrote:
> +
> +/* Swapfile activation */
> +
> +struct iomap_swapfile_info {
> + struct swap_info_struct *sis;
> + uint64_t lowest_ppage; /* lowest physical addr seen (pages) */
> + uint64_t highest_ppage; /* highest physical addr seen (pages) */
> + unsigned long expected_page_no; /* next logical offset wanted (pages) */
> + int nr_extents; /* extent count */
> +};
> +
> +static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
> + loff_t count, void *data, struct iomap *iomap)
> +{
> + struct iomap_swapfile_info *isi = data;
> + unsigned long page_no = iomap->offset >> PAGE_SHIFT;
> + unsigned long nr_pages = iomap->length >> PAGE_SHIFT;
> + uint64_t first_ppage = iomap->addr >> PAGE_SHIFT;
> + uint64_t last_ppage = ((iomap->addr + iomap->length) >> PAGE_SHIFT) - 1;
> +
> + /* Only one bdev per swap file. */
> + if (iomap->bdev != isi->sis->bdev)
> + goto err;
> +
> + /* Must be aligned to a page boundary. */
> + if ((iomap->offset & ~PAGE_MASK) || (iomap->addr & ~PAGE_MASK) ||
> + (iomap->length & ~PAGE_MASK))
> + goto err;
Reporting error in this case does not look equivalent to
generic_swapfile_activate()? That function just skips blocks with
insufficient alignment... And I'm actually puzzled why alignment of
physical block is needed but that's independent question.
> + /* Only real or unwritten extents. */
> + if (iomap->type != IOMAP_MAPPED && iomap->type != IOMAP_UNWRITTEN)
> + goto err;
> +
> + /* No sparse files. */
> + if (isi->expected_page_no != page_no)
> + goto err;
> +
> + /* No uncommitted metadata or shared blocks or inline data. */
> + if (iomap->flags & (IOMAP_F_DIRTY | IOMAP_F_SHARED |
> + IOMAP_F_DATA_INLINE))
> + goto err;
> +
> + /*
> + * Calculate how much swap space we're adding; the first page contains
> + * the swap header and doesn't count.
> + */
> + if (page_no == 0)
> + first_ppage++;
> + if (isi->lowest_ppage > first_ppage)
> + isi->lowest_ppage = first_ppage;
> + if (isi->highest_ppage < last_ppage)
> + isi->highest_ppage = last_ppage;
> +
> + /* Add extent, set up for the next call. */
> + isi->nr_extents += add_swap_extent(isi->sis, page_no, nr_pages,
> + first_ppage);
And here add_swap_extent() can return error.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
