On Tue, Jul 01, 2025 at 10:48:47PM +0800, alexjlzheng@xxxxxxxxx wrote:
> From: Jinliang Zheng <alexjlzheng@xxxxxxxxxxx>
>
> In the buffer write path, iomap_set_range_uptodate() is called every
> time iomap_end_write() is called. But if folio_test_uptodate() holds, we
> know that all blocks in this folio are already in the uptodate state, so
> there is no need to go deep into the critical section of state_lock to
> execute bitmap_set().
>
> Although state_lock may not have significant lock contention due to
> folio lock, this patch at least reduces the number of instructions.
>
> Signed-off-by: Jinliang Zheng <alexjlzheng@xxxxxxxxxxx>
> ---
> fs/iomap/buffered-io.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 3729391a18f3..fb4519158f3a 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -71,6 +71,9 @@ static void iomap_set_range_uptodate(struct folio *folio, size_t off,
> unsigned long flags;
> bool uptodate = true;
>
> + if (folio_test_uptodate(folio))
> + return;
Looks fine, but how exhaustively have you tested this with heavy IO
workloads? I /think/ it's the case that folios always creep towards
ifs_is_fully_uptodate() == true state and once they've gotten there
never go back. But folio state bugs are tricky to detect once they've
crept in.
--D
> +
> if (ifs) {
> spin_lock_irqsave(&ifs->state_lock, flags);
> uptodate = ifs_set_range_uptodate(folio, ifs, off, len);
> --
> 2.49.0
>
>
