fs: hfsplus: initialize fsdata in hfsplus_file_truncate()

When aops->write_begin() does not initialize fsdata, KMSAN may report an
error passing the latter to aops->write_end().

Fix this by unconditionally initializing fsdata.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexander Potapenko <[email protected]>
Suggested-by: Eric Biggers <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: ramosian-glider

fs/hfsplus/extents.c

@@ -554,7 +554,7 @@ void hfsplus_file_truncate(struct inode *inode)
 	if (inode->i_size > hip->phys_size) {
 		struct address_space *mapping = inode->i_mapping;
 		struct page *page;
-		void *fsdata;
+		void *fsdata = NULL;
 		loff_t size = inode->i_size;
 
 		res = hfsplus_write_begin(NULL, mapping, size, 0,