2021-04-28 21:08:33

by Vivek Goyal

Subject: [PATCH v6 0/3] dax: Fix missed wakeup in put_unlocked_entry()

Hi,

This is V6. Only change since V5 is that I changed order of WAKE_NEXT
and WAKE_ALL in comments too.

Vivek

Vivek Goyal (3):
dax: Add an enum for specifying dax wakup mode
dax: Add a wakeup mode parameter to put_unlocked_entry()
dax: Wake up all waiters after invalidating dax entry

fs/dax.c | 35 +++++++++++++++++++++++------------
1 file changed, 23 insertions(+), 12 deletions(-)

--
2.25.4

2021-04-28 21:09:30

by Vivek Goyal

Subject: [PATCH v6 2/3] dax: Add a wakeup mode parameter to put_unlocked_entry()

As of now put_unlocked_entry() always wakes up next waiter. In next
patches we want to wake up all waiters at one callsite. Hence, add a
parameter to the function.

This patch does not introduce any change of behavior.

Reviewed-by: Greg Kurz <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Suggested-by: Dan Williams <[email protected]>
Signed-off-by: Vivek Goyal <[email protected]>
---
fs/dax.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 5ecee51c44ee..56eb1c759ca5 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -275,11 +275,11 @@ static void wait_entry_unlocked(struct xa_state *xas, void *entry)
finish_wait(wq, &ewait.wait);
}

-static void put_unlocked_entry(struct xa_state *xas, void *entry)
+static void put_unlocked_entry(struct xa_state *xas, void *entry,
+ enum dax_wake_mode mode)
{
- /* If we were the only waiter woken, wake the next one */
if (entry && !dax_is_conflict(entry))
- dax_wake_entry(xas, entry, WAKE_NEXT);
+ dax_wake_entry(xas, entry, mode);
}

/*
@@ -633,7 +633,7 @@ struct page *dax_layout_busy_page_range(struct address_space *mapping,
entry = get_unlocked_entry(&xas, 0);
if (entry)
page = dax_busy_page(entry);
- put_unlocked_entry(&xas, entry);
+ put_unlocked_entry(&xas, entry, WAKE_NEXT);
if (page)
break;
if (++scanned % XA_CHECK_SCHED)
@@ -675,7 +675,7 @@ static int __dax_invalidate_entry(struct address_space *mapping,
mapping->nrexceptional--;
ret = 1;
out:
- put_unlocked_entry(&xas, entry);
+ put_unlocked_entry(&xas, entry, WAKE_NEXT);
xas_unlock_irq(&xas);
return ret;
}
@@ -954,7 +954,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
return ret;

put_unlocked:
- put_unlocked_entry(xas, entry);
+ put_unlocked_entry(xas, entry, WAKE_NEXT);
return ret;
}

@@ -1695,7 +1695,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
/* Did we race with someone splitting entry or so? */
if (!entry || dax_is_conflict(entry) ||
(order == 0 && !dax_is_pte_entry(entry))) {
- put_unlocked_entry(&xas, entry);
+ put_unlocked_entry(&xas, entry, WAKE_NEXT);
xas_unlock_irq(&xas);
trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
VM_FAULT_NOPAGE);
--
2.25.4

2021-04-28 21:11:59

by Dan Williams

Subject: Re: [PATCH v6 0/3] dax: Fix missed wakeup in put_unlocked_entry()

On Wed, Apr 28, 2021 at 12:03 PM Vivek Goyal <[email protected]> wrote:
>
> Hi,
>
> This is V6. Only change since V5 is that I changed order of WAKE_NEXT
> and WAKE_ALL in comments too.
>
> Vivek
>
> Vivek Goyal (3):
> dax: Add an enum for specifying dax wakup mode
> dax: Add a wakeup mode parameter to put_unlocked_entry()
> dax: Wake up all waiters after invalidating dax entry

Thanks Vivek, looks good.