On Tue, 1 Jul 2025 11:47:37 -0700, djwong@xxxxxxxxxx wrote:
> On Tue, Jul 03, 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.
I tested fio, ltp and xfstests combined for about 30 hours. The command
used for fio test is:
fio --name=4k-rw \
--filename=/data2/testfile \
--size=1G \
--bs=4096 \
--ioengine=libaio \
--iodepth=32 \
--rw=randrw \
--direct=0 \
--buffered=1 \
--numjobs=16 \
--runtime=60 \
--time_based \
--group_reporting
ltp and xfstests showed no noticeable errors caused by this patch.
thanks,
Jinliang Zheng. :)
>
> --D
>
> > +
> > if (ifs) {
> > spin_lock_irqsave(&ifs->state_lock, flags);
> > uptodate = ifs_set_range_uptodate(folio, ifs, off, len);
> > --
> > 2.49.0
> >
> >
