[PATCH 3.16.y-ckt 170/170] mm: Remove false WARN_ON from pagecache_isize_extended()

[Luis Henriques]

3.16.7-ckt1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack at suse.cz>

commit f55fefd1a5a339b1bd08c120b93312d6eb64a9fb upstream.

The WARN_ON checking whether i_mutex is held in
pagecache_isize_extended() was wrong because some filesystems (e.g.
XFS) use different locks for serialization of truncates / writes. So
just remove the check.

Signed-off-by: Jan Kara <jack at suse.cz>
Reviewed-by: Dave Chinner <dchinner at redhat.com>
Signed-off-by: Dave Chinner <david at fromorbit.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 mm/truncate.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/mm/truncate.c b/mm/truncate.c
index ed6e91a695e0..699494e6aba5 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -764,7 +764,6 @@ void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
 	struct page *page;
 	pgoff_t index;
 
-	WARN_ON(!mutex_is_locked(&inode->i_mutex));
 	WARN_ON(to > inode->i_size);
 
 	if (from >= to || bsize == PAGE_CACHE_SIZE)
-- 
2.1.0