ext4: don't wait for extent conversion in ext4_punch_hole()

We don't have to wait for extent conversion in ext4_punch_hole() as
buffered IO for the punched range has been flushed and waited upon
(thus all extent conversions for that range have completed).  Also we
wait for all DIO to finish using inode_dio_wait() so there cannot be
any extent conversions pending due to direct IO.

Also remove ext4_flush_unwritten_io() since it's unused now.
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4.h

@@ -1998,7 +1998,6 @@ static inline  unsigned char get_dtype(struct super_block *sb, int filetype)
 
 /* fsync.c */
 extern int ext4_sync_file(struct file *, loff_t, loff_t, int);
-extern int ext4_flush_unwritten_io(struct inode *);
 
 /* hash.c */
 extern int ext4fs_dirhash(const char *name, int len, struct

fs/ext4/inode.c

@@ -3522,9 +3522,6 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 
 	/* Wait all existing dio workers, newcomers will block on i_mutex */
 	ext4_inode_block_unlocked_dio(inode);
-	ret = ext4_flush_unwritten_io(inode);
-	if (ret)
-		goto out_dio;
 	inode_dio_wait(inode);
 
 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))

fs/ext4/page-io.c

@@ -281,22 +281,6 @@ void ext4_end_io_unrsv_work(struct work_struct *work)
 	ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_unrsv_conversion_list);
 }
 
-int ext4_flush_unwritten_io(struct inode *inode)
-{
-	int ret, err;
-
-	WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) &&
-		     !(inode->i_state & I_FREEING));
-	ret = ext4_do_flush_completed_IO(inode,
-					 &EXT4_I(inode)->i_rsv_conversion_list);
-	err = ext4_do_flush_completed_IO(inode,
-					 &EXT4_I(inode)->i_unrsv_conversion_list);
-	if (!ret)
-		ret = err;
-	ext4_unwritten_wait(inode);
-	return ret;
-}
-
 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 {
 	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);