linux-kernel - Re: [PATCH v2 03/10] ext4: drop ext4_update_disksize_before

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Message-ID: <20240920161351.ax3oidpt6w6bf3o4@quack3>
Date: Fri, 20 Sep 2024 18:13:51 +0200
From: Jan Kara <jack@...e.cz>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, tytso@....edu,
	adilger.kernel@...ger.ca, jack@...e.cz, ritesh.list@...il.com,
	yi.zhang@...wei.com, chengzhihao1@...wei.com, yukuai3@...wei.com
Subject: Re: [PATCH v2 03/10] ext4: drop ext4_update_disksize_before_punch()

On Wed 04-09-24 14:29:18, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
> 
> Since we always write back dirty data before zeroing range and punching
> hole, the delalloc extended file's disksize of should be updated
> properly when writing back pages, hence we don't need to update file's
> disksize before discarding page cache in ext4_zero_range() and
> ext4_punch_hole(), just drop ext4_update_disksize_before_punch().
> 
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>

So when we don't write out before hole punching & company this needs to stay
in some shape or form. 

								Honza

> ---
>  fs/ext4/ext4.h    |  3 ---
>  fs/ext4/extents.c |  4 ----
>  fs/ext4/inode.c   | 37 +------------------------------------
>  3 files changed, 1 insertion(+), 43 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 08acd152261e..e8d7965f62c4 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -3414,9 +3414,6 @@ static inline int ext4_update_inode_size(struct inode *inode, loff_t newsize)
>  	return changed;
>  }
>  
> -int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
> -				      loff_t len);
> -
>  struct ext4_group_info {
>  	unsigned long   bb_state;
>  #ifdef AGGRESSIVE_CHECK
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 19a9b14935b7..d9fccf2970e9 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4637,10 +4637,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
>  		flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |
>  			  EXT4_EX_NOCACHE);
>  
> -		ret = ext4_update_disksize_before_punch(inode, offset, len);
> -		if (ret)
> -			goto out_invalidate_lock;
> -
>  		/* Now release the pages and zero block aligned part of pages */
>  		truncate_pagecache_range(inode, start, end - 1);
>  
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 8af25442d44d..9343ce9f2b01 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3872,37 +3872,6 @@ int ext4_can_truncate(struct inode *inode)
>  	return 0;
>  }
>  
> -/*
> - * We have to make sure i_disksize gets properly updated before we truncate
> - * page cache due to hole punching or zero range. Otherwise i_disksize update
> - * can get lost as it may have been postponed to submission of writeback but
> - * that will never happen after we truncate page cache.
> - */
> -int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
> -				      loff_t len)
> -{
> -	handle_t *handle;
> -	int ret;
> -
> -	loff_t size = i_size_read(inode);
> -
> -	WARN_ON(!inode_is_locked(inode));
> -	if (offset > size || offset + len < size)
> -		return 0;
> -
> -	if (EXT4_I(inode)->i_disksize >= size)
> -		return 0;
> -
> -	handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
> -	if (IS_ERR(handle))
> -		return PTR_ERR(handle);
> -	ext4_update_i_disksize(inode, size);
> -	ret = ext4_mark_inode_dirty(handle, inode);
> -	ext4_journal_stop(handle);
> -
> -	return ret;
> -}
> -
>  static void ext4_wait_dax_page(struct inode *inode)
>  {
>  	filemap_invalidate_unlock(inode->i_mapping);
> @@ -4022,13 +3991,9 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
>  	last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
>  
>  	/* Now release the pages and zero block aligned part of pages*/
> -	if (last_block_offset > first_block_offset) {
> -		ret = ext4_update_disksize_before_punch(inode, offset, length);
> -		if (ret)
> -			goto out_dio;
> +	if (last_block_offset > first_block_offset)
>  		truncate_pagecache_range(inode, first_block_offset,
>  					 last_block_offset);
> -	}
>  
>  	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
>  		credits = ext4_writepage_trans_blocks(inode);
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR