linux-ext4 - Re: [PATCH v2] ext4: dax: keep orphan list before truncate overflow allocated blocks

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Message-ID: <20240829122131.xa44p2nfwqwptmtr@quack3>
Date: Thu, 29 Aug 2024 14:21:31 +0200
From: Jan Kara <jack@...e.cz>
To: Yang Erkun <yangerkun@...weicloud.com>
Cc: tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz,
	linux-ext4@...r.kernel.org, yangerkun@...wei.com
Subject: Re: [PATCH v2] ext4: dax: keep orphan list before truncate overflow
 allocated blocks

On Thu 29-08-24 19:02:22, Yang Erkun wrote:
> From: yangerkun <yangerkun@...wei.com>
> 
> Any extending write for ext4 requires the inode to be placed on the
> orphan list before the actual write. In addition, the inode can be
> actually removed from the orphan list only after all writes are
> completed. Otherwise we'd leave allocated blocks beyond i_disksize if we
> could not copy all the data into allocated block and e2fsck would
> complain.
> 
> Currently, direct IO and buffered IO comply with this logic(buffered
> IO will truncate all overflow allocated blocks that has not been
> written successfully, and direct IO will truncate all allocated blocks
> when error occurs). However, dax write break this since dax write will
> remove the inode from the orphan list by calling
> ext4_handle_inode_extension unconditionally during extending write.
> 
> We add a argument to help determine does we do a fully write, and for
> the case not fully write, we leave the inode on the orphan list, and the
> latter ext4_inode_extension_cleanup will help us truncate the overflow
> allocated blocks, and then remove the inode from the orphan list.
> 
> Signed-off-by: yangerkun <yangerkun@...wei.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/ext4/file.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index be061bb64067..f14aed14b9cf 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -306,7 +306,7 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
>  }
>  
>  static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
> -					   ssize_t count)
> +					   ssize_t written, ssize_t count)
>  {
>  	handle_t *handle;
>  
> @@ -315,7 +315,7 @@ static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
>  	if (IS_ERR(handle))
>  		return PTR_ERR(handle);
>  
> -	if (ext4_update_inode_size(inode, offset + count)) {
> +	if (ext4_update_inode_size(inode, offset + written)) {
>  		int ret = ext4_mark_inode_dirty(handle, inode);
>  		if (unlikely(ret)) {
>  			ext4_journal_stop(handle);
> @@ -323,11 +323,11 @@ static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
>  		}
>  	}
>  
> -	if (inode->i_nlink)
> +	if ((written == count) && inode->i_nlink)
>  		ext4_orphan_del(handle, inode);
>  	ext4_journal_stop(handle);
>  
> -	return count;
> +	return written;
>  }
>  
>  /*
> @@ -393,7 +393,7 @@ static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
>  	if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize) &&
>  	    pos + size <= i_size_read(inode))
>  		return size;
> -	return ext4_handle_inode_extension(inode, pos, size);
> +	return ext4_handle_inode_extension(inode, pos, size, size);
>  }
>  
>  static const struct iomap_dio_ops ext4_dio_write_ops = {
> @@ -669,7 +669,7 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  	ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
>  
>  	if (extend) {
> -		ret = ext4_handle_inode_extension(inode, offset, ret);
> +		ret = ext4_handle_inode_extension(inode, offset, ret, count);
>  		ext4_inode_extension_cleanup(inode, ret < (ssize_t)count);
>  	}
>  out:
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR