gfs2: Fix gfs2_file_buffered_write endless loop workaround

[ Upstream commit 46f3e0421ccb5474b5c006b0089b9dfd42534bb6 ]

Since commit 554c577cee95b, gfs2_file_buffered_write() can accidentally
return a truncated iov_iter, which might confuse callers.  Fix that.

Fixes: 554c577cee95b ("gfs2: Prevent endless loops in gfs2_file_buffered_write")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/gfs2/file.c

@@ -1086,6 +1086,7 @@ out_uninit:
 	gfs2_holder_uninit(gh);
 	if (statfs_gh)
 		kfree(statfs_gh);
+	from->count = orig_count - read;
 	return read ? read : ret;
 }