READ_ONLY_THP_FOR_FS is no longer present, delete related code.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 fs/open.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index 91f1139591ab..cef382d9d8b8 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -970,33 +970,6 @@ static int do_dentry_open(struct file *f,
 	if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
 		return -EINVAL;
 
-	/*
-	 * XXX: Huge page cache doesn't support writing yet. Drop all page
-	 * cache for this file before processing writes.
-	 */
-	if (f->f_mode & FMODE_WRITE) {
-		/*
-		 * Depends on full fence from get_write_access() to synchronize
-		 * against collapse_file() regarding i_writecount and nr_thps
-		 * updates. Ensures subsequent insertion of THPs into the page
-		 * cache will fail.
-		 */
-		if (filemap_nr_thps(inode->i_mapping)) {
-			struct address_space *mapping = inode->i_mapping;
-
-			filemap_invalidate_lock(inode->i_mapping);
-			/*
-			 * unmap_mapping_range just need to be called once
-			 * here, because the private pages is not need to be
-			 * unmapped mapping (e.g. data segment of dynamic
-			 * shared libraries here).
-			 */
-			unmap_mapping_range(mapping, 0, 0, 0);
-			truncate_inode_pages(mapping, 0);
-			filemap_invalidate_unlock(inode->i_mapping);
-		}
-	}
-
 	return 0;
 
 cleanup_all:
-- 
2.43.0