From: Matthew Wilcox <willy@infradead.org>
Date: Tue, 6 Nov 2018 18:11:57 +0000 (-0500)
Subject: dax: Remove optimisation from dax_lock_mapping_entry
X-Git-Tag: v5.15~7540^2~6
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6d7cd8c1373746a93dc868ee9d38a82df78b38aa;p=platform%2Fkernel%2Flinux-starfive.git

dax: Remove optimisation from dax_lock_mapping_entry

Skipping some of the revalidation after we sleep can lead to returning
a mapping which has already been freed.  Just drop this optimisation.

Reported-by: Dan Williams <dan.j.williams@intel.com>
Fixes: 9f32d221301c ("dax: Convert dax_lock_mapping_entry to XArray")
Signed-off-by: Matthew Wilcox <willy@infradead.org>
---

diff --git a/fs/dax.c b/fs/dax.c
index 616e36e..529ac9d 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -383,11 +383,8 @@ bool dax_lock_mapping_entry(struct page *page)
 		entry = xas_load(&xas);
 		if (dax_is_locked(entry)) {
 			entry = get_unlocked_entry(&xas);
-			/* Did the page move while we slept? */
-			if (dax_to_pfn(entry) != page_to_pfn(page)) {
-				xas_unlock_irq(&xas);
-				continue;
-			}
+			xas_unlock_irq(&xas);
+			continue;
 		}
 		dax_lock_entry(&xas, entry);
 		xas_unlock_irq(&xas);