fs: hfs: initialize fsdata in hfs_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]>

fs/hfs/extent.c

@@ -486,7 +486,7 @@ void hfs_file_truncate(struct inode *inode)
 		inode->i_size);
 	if (inode->i_size > HFS_I(inode)->phys_size) {
 		struct address_space *mapping = inode->i_mapping;
-		void *fsdata;
+		void *fsdata = NULL;
 		struct page *page;
 
 		/* XXX: Can use generic_cont_expand? */