hfsplus: fix return value of hfsplus_get_block()

Direct writes to empty inodes fail with EIO.  The generic direct-io code
is in part to blame (a patch has been submitted as "direct-io: allow
direct writes to empty inodes"), but hfsplus is worse affected than the
other filesystems because the fallback to buffered I/O doesn't happen.

The problem is the return value of hfsplus_get_block() when called with
!create.  Change it to be more consistent with the other modules.

Link: http://lkml.kernel.org/r/2cd1301404ec7cf1e39c8f11a01a4302f1460ad6.1539195310.git.ernesto.mnd.fernandez@gmail.comSigned-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Reviewed-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/hfsplus/extents.c

@@ -237,7 +237,9 @@ int hfsplus_get_block(struct inode *inode, sector_t iblock,
 	ablock = iblock >> sbi->fs_shift;
 
 	if (iblock >= hip->fs_blocks) {
-		if (iblock > hip->fs_blocks || !create)
+		if (!create)
+			return 0;
+		if (iblock > hip->fs_blocks)
 			return -EIO;
 		if (ablock >= hip->alloc_blocks) {
 			res = hfsplus_file_extend(inode, false);