* [4.19-stable PATCH] dax: Avoid losing wakeup in dax_lock_mapping_entry
[not found] <20181126142743.GA25618@bombadil.infradead.org>
@ 2018-11-28 18:53 ` Dan Williams
2018-11-29 8:04 ` Greg KH
0 siblings, 1 reply; 2+ messages in thread
From: Dan Williams @ 2018-11-28 18:53 UTC (permalink / raw)
To: stable; +Cc: Matthew Wilcox, linux-nvdimm, linux-kernel, linux-fsdevel
From: Matthew Wilcox <willy@infradead.org>
commit 25bbe21bf427a81b8e3ccd480ea0e1d940256156 upstream.
After calling get_unlocked_entry(), you have to call
put_unlocked_entry() to avoid subsequent waiters losing wakeups.
Fixes: c2a7d2a11552 ("filesystem-dax: Introduce dax_lock_mapping_entry()")
Cc: <stable@vger.kernel.org>
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
Passes the nvdimm unit test suite which exercises the lock path.
fs/dax.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/dax.c b/fs/dax.c
index 0fb270f0a0ef..b0cd1364c68f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -217,6 +217,9 @@ static inline void *unlock_slot(struct address_space *mapping, void **slot)
return (void *)entry;
}
+static void put_unlocked_mapping_entry(struct address_space *mapping,
+ pgoff_t index, void *entry);
+
/*
* Lookup entry in radix tree, wait for it to become unlocked if it is
* exceptional entry and return it. The caller must call
@@ -256,8 +259,10 @@ static void *__get_unlocked_mapping_entry(struct address_space *mapping,
revalidate = wait_fn();
finish_wait(wq, &ewait.wait);
xa_lock_irq(&mapping->i_pages);
- if (revalidate)
+ if (revalidate) {
+ put_unlocked_mapping_entry(mapping, index, entry);
return ERR_PTR(-EAGAIN);
+ }
}
}
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