ext4: Avoid writeback path when fs is shut down

Patch suggtestd by Teodore Ts'o in

https://lore.kernel.org/linux-ext4/4e83fb26-4d4a-d482-640c-8104973b7ebf@molgen.mpg.de/T/#u

to avoid the error

EXT4-fs (dm-0): ext4_writepages: jbd2_start: 5120 pages, ino 11; err -5

which sometimed occurs, when we set the fs to EXT4_IOC_SHUTDOWN+EXT4_GOING_FLAGS_NOLOGFLUSH

fs/ext4/super.c

@@ -523,6 +523,10 @@ static int ext4_journalled_submit_inode_data_buffers(struct jbd2_inode *jinode)
 static int ext4_journal_submit_inode_data_buffers(struct jbd2_inode *jinode)
 {
 	int ret;
+	journal_t *journal = EXT4_SB(jinode->i_vfs_inode->i_sb)->s_journal;
+
+	if (!journal || is_journal_aborted(journal))
+		return 0;
 
 	if (ext4_should_journal_data(jinode->i_vfs_inode))
 		ret = ext4_journalled_submit_inode_data_buffers(jinode);
@@ -535,6 +539,10 @@ static int ext4_journal_submit_inode_data_buffers(struct jbd2_inode *jinode)
 static int ext4_journal_finish_inode_data_buffers(struct jbd2_inode *jinode)
 {
 	int ret = 0;
+	journal_t *journal = EXT4_SB(jinode->i_vfs_inode->i_sb)->s_journal;
+
+	if (!journal || is_journal_aborted(journal))
+		return 0;
 
 	if (!ext4_should_journal_data(jinode->i_vfs_inode))
 		ret = jbd2_journal_finish_inode_data_buffers(jinode);