On Thu, Jul 30, 2020 at 09:19:01AM +0800, Yu Kuai wrote:
> +++ b/fs/iomap/buffered-io.c
> @@ -29,7 +29,9 @@ struct iomap_page {
> atomic_t read_count;
> atomic_t write_count;
> spinlock_t uptodate_lock;
> + spinlock_t dirty_lock;
No need for a separate spinlock. Just rename uptodate_lock. Maybe
'bitmap_lock'.
> DECLARE_BITMAP(uptodate, PAGE_SIZE / 512);
> + DECLARE_BITMAP(dirty, PAGE_SIZE / 512);
This is inefficient and poses difficulties for the THP patchset.
Maybe let the discussion on removing the ->uptodate array finish
before posting another patch for review?
> +static void
> +iomap_iop_set_or_clear_range_dirty(
> + struct page *page,
> + unsigned int off,
> + unsigned int len,
> + bool is_set)
Please follow normal kernel programming style. This isn't XFS.
Also 'set or clear' with a bool to indicate which to do is horrible
style. Separate functions!
> @@ -1386,7 +1432,8 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> for (i = 0, file_offset = page_offset(page);
> i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
> i++, file_offset += len) {
> - if (iop && !test_bit(i, iop->uptodate))
> + if (iop && (!test_bit(i, iop->uptodate) ||
> + !test_bit(i, iop->dirty)))
> continue;
Surely we don't need to test ->uptodate here at all. Why would we write
back a block which isn't dirty?
