Re: [PATCH 25/29] ext4: Use generic_file_fsync() in ext4_file_fsync() in nojournal mode

[Zheng Liu <gnehzuil.liu@gmail.com>]

On Mon, Apr 08, 2013 at 11:32:30PM +0200, Jan Kara wrote:
> Just use the generic function instead of duplicating it. We only need
> to reshuffle the read-only check a bit (which is there to prevent
> writing to a filesystem which has been remounted read-only after error
> I assume).
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

A minor nit below.  Otherwise the patch looks good to me.
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>

> ---
>  fs/ext4/fsync.c |   45 ++++++++++-----------------------------------
>  1 files changed, 10 insertions(+), 35 deletions(-)
> 
> diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
> index e02ba1b..1c08780 100644
> --- a/fs/ext4/fsync.c
> +++ b/fs/ext4/fsync.c
> @@ -73,32 +73,6 @@ static int ext4_sync_parent(struct inode *inode)
>  	return ret;
>  }
>  
> -/**
> - * __sync_file - generic_file_fsync without the locking and filemap_write
> - * @inode:	inode to sync
> - * @datasync:	only sync essential metadata if true
> - *
> - * This is just generic_file_fsync without the locking.  This is needed for
> - * nojournal mode to make sure this inodes data/metadata makes it to disk
> - * properly.  The i_mutex should be held already.
> - */
> -static int __sync_inode(struct inode *inode, int datasync)
> -{
> -	int err;
> -	int ret;
> -
> -	ret = sync_mapping_buffers(inode->i_mapping);
> -	if (!(inode->i_state & I_DIRTY))
> -		return ret;
> -	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
> -		return ret;
> -
> -	err = sync_inode_metadata(inode, 1);
> -	if (ret == 0)
> -		ret = err;
> -	return ret;
> -}
> -
>  /*
>   * akpm: A new design for ext4_sync_file().
>   *
> @@ -116,7 +90,7 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
>  	struct inode *inode = file->f_mapping->host;
>  	struct ext4_inode_info *ei = EXT4_I(inode);
>  	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
> -	int ret, err;
> +	int ret = 0, err;
>  	tid_t commit_tid;
>  	bool needs_barrier = false;
>  
> @@ -124,21 +98,21 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
>  
>  	trace_ext4_sync_file_enter(file, datasync);
>  
> -	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
> -	if (ret)
> -		return ret;
> -	mutex_lock(&inode->i_mutex);
> -
>  	if (inode->i_sb->s_flags & MS_RDONLY)
> -		goto out;
> +		goto out_trace;
>  
>  	if (!journal) {
> -		ret = __sync_inode(inode, datasync);
> +		ret = generic_file_fsync(file, start, end, datasync);
>  		if (!ret && !hlist_empty(&inode->i_dentry))
>  			ret = ext4_sync_parent(inode);
>  		goto out;
                     ^^^^
                goto out_trace;
Otherwise we will unlock i_mutex that we haven't take it.

Regards
                                                - Zheng

>  	}
>  
> +	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
> +	if (ret)
> +		return ret;
> +	mutex_lock(&inode->i_mutex);
> +
>  	/*
>  	 * data=writeback,ordered:
>  	 *  The caller's filemap_fdatawrite()/wait will sync the data.
> @@ -169,8 +143,9 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
>  		if (!ret)
>  			ret = err;
>  	}
> - out:
> +out:
>  	mutex_unlock(&inode->i_mutex);
> +out_trace:
>  	trace_ext4_sync_file_exit(inode, ret);
>  	return ret;
>  }
> -- 
> 1.7.1
> 
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