Re: [PATCH 4/5] ext4: remove unused member 'i_unwritten' from 'ext4_inode_info'

[Jan Kara <jack@suse.cz>]

On Fri 20-12-24 14:07:56, libaokun@huaweicloud.com wrote:
> From: Baokun Li <libaokun1@huawei.com>
> 
> After commit 378f32bab371 ("ext4: introduce direct I/O write using iomap
> infrastructure"), no one cares about the value of i_unwritten, so there
> is no need to maintain this variable, remove it, and clean up the
> associated logic.
> 
> Suggested-by: Zhang Yi <yi.zhang@huawei.com>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>

Good spotting! Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/ext4/ext4.h  | 22 +++-------------------
>  fs/ext4/inode.c |  2 +-
>  fs/ext4/super.c |  9 +--------
>  3 files changed, 5 insertions(+), 28 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 9da0e32af02a..203a900fd789 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1059,7 +1059,6 @@ struct ext4_inode_info {
>  
>  	/* Number of ongoing updates on this inode */
>  	atomic_t  i_fc_updates;
> -	atomic_t i_unwritten; /* Nr. of inflight conversions pending */
>  
>  	/* Fast commit wait queue for this inode */
>  	wait_queue_head_t i_fc_wait;
> @@ -3786,34 +3785,19 @@ static inline void set_bitmap_uptodate(struct buffer_head *bh)
>  	set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state);
>  }
>  
> -/* For ioend & aio unwritten conversion wait queues */
> -#define EXT4_WQ_HASH_SZ		37
> -#define ext4_ioend_wq(v)   (&ext4__ioend_wq[((unsigned long)(v)) %\
> -					    EXT4_WQ_HASH_SZ])
> -extern wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
> -
>  extern int ext4_resize_begin(struct super_block *sb);
>  extern int ext4_resize_end(struct super_block *sb, bool update_backups);
>  
> -static inline void ext4_set_io_unwritten_flag(struct inode *inode,
> -					      struct ext4_io_end *io_end)
> +static inline void ext4_set_io_unwritten_flag(struct ext4_io_end *io_end)
>  {
> -	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
> +	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN))
>  		io_end->flag |= EXT4_IO_END_UNWRITTEN;
> -		atomic_inc(&EXT4_I(inode)->i_unwritten);
> -	}
>  }
>  
>  static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
>  {
> -	struct inode *inode = io_end->inode;
> -
> -	if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
> +	if (io_end->flag & EXT4_IO_END_UNWRITTEN)
>  		io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
> -		/* Wake up anyone waiting on unwritten extent conversion */
> -		if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
> -			wake_up_all(ext4_ioend_wq(inode));
> -	}
>  }
>  
>  extern const struct iomap_ops ext4_iomap_ops;
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 7c54ae5fcbd4..36b1f9fb690a 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2225,7 +2225,7 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
>  			mpd->io_submit.io_end->handle = handle->h_rsv_handle;
>  			handle->h_rsv_handle = NULL;
>  		}
> -		ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
> +		ext4_set_io_unwritten_flag(mpd->io_submit.io_end);
>  	}
>  
>  	BUG_ON(map->m_len == 0);
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index a50e5c31b937..853997655e40 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1426,7 +1426,6 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
>  	spin_lock_init(&ei->i_completed_io_lock);
>  	ei->i_sync_tid = 0;
>  	ei->i_datasync_tid = 0;
> -	atomic_set(&ei->i_unwritten, 0);
>  	INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
>  	ext4_fc_init_inode(&ei->vfs_inode);
>  	mutex_init(&ei->i_fc_lock);
> @@ -7381,12 +7380,9 @@ static struct file_system_type ext4_fs_type = {
>  };
>  MODULE_ALIAS_FS("ext4");
>  
> -/* Shared across all ext4 file systems */
> -wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
> -
>  static int __init ext4_init_fs(void)
>  {
> -	int i, err;
> +	int err;
>  
>  	ratelimit_state_init(&ext4_mount_msg_ratelimit, 30 * HZ, 64);
>  	ext4_li_info = NULL;
> @@ -7394,9 +7390,6 @@ static int __init ext4_init_fs(void)
>  	/* Build-time check for flags consistency */
>  	ext4_check_flag_values();
>  
> -	for (i = 0; i < EXT4_WQ_HASH_SZ; i++)
> -		init_waitqueue_head(&ext4__ioend_wq[i]);
> -
>  	err = ext4_init_es();
>  	if (err)
>  		return err;
> -- 
> 2.46.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR