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Message-ID: <Zq1IfX3R7YSf6n5R@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com>
Date: Sat, 3 Aug 2024 02:28:37 +0530
From: Ojaswin Mujoo <ojaswin@...ux.ibm.com>
To: libaokun@...weicloud.com
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
        jack@...e.cz, ritesh.list@...il.com, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com, yangerkun@...wei.com,
        Baokun Li <libaokun1@...wei.com>
Subject: Re: [PATCH 20/20] ext4: avoid unnecessary extent path frees and
 allocations

On Wed, Jul 10, 2024 at 12:06:54PM +0800, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
> 
> The ext4_find_extent() can update the extent path so that it does not have
> to allocate and free the path repeatedly, thus reducing the consumption of
> memory allocation and freeing in the following functions:
> 
>     ext4_ext_clear_bb
>     ext4_ext_replay_set_iblocks
>     ext4_fc_replay_add_range
>     ext4_fc_set_bitmaps_and_counters
> 
> No functional changes. Note that ext4_find_extent() does not support error
> pointers, so in this case set path to NULL first.
> 
> Signed-off-by: Baokun Li <libaokun1@...wei.com>

Looks good Baokun, feel free to add:

Reviewed-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com>

Regards,
ojaswin

> ---
>  fs/ext4/extents.c     | 51 +++++++++++++++++++------------------------
>  fs/ext4/fast_commit.c | 11 ++++++----
>  2 files changed, 29 insertions(+), 33 deletions(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 737432bb316e..5ff92cd50dc8 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -6068,12 +6068,9 @@ int ext4_ext_replay_set_iblocks(struct inode *inode)
>  	if (IS_ERR(path))
>  		return PTR_ERR(path);
>  	ex = path[path->p_depth].p_ext;
> -	if (!ex) {
> -		ext4_free_ext_path(path);
> +	if (!ex)
>  		goto out;
> -	}
>  	end = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
> -	ext4_free_ext_path(path);
>  
>  	/* Count the number of data blocks */
>  	cur = 0;
> @@ -6099,32 +6096,28 @@ int ext4_ext_replay_set_iblocks(struct inode *inode)
>  	ret = skip_hole(inode, &cur);
>  	if (ret < 0)
>  		goto out;
> -	path = ext4_find_extent(inode, cur, NULL, 0);
> +	path = ext4_find_extent(inode, cur, path, 0);
>  	if (IS_ERR(path))
>  		goto out;
>  	numblks += path->p_depth;
> -	ext4_free_ext_path(path);
>  	while (cur < end) {
> -		path = ext4_find_extent(inode, cur, NULL, 0);
> +		path = ext4_find_extent(inode, cur, path, 0);
>  		if (IS_ERR(path))
>  			break;
>  		ex = path[path->p_depth].p_ext;
> -		if (!ex) {
> -			ext4_free_ext_path(path);
> -			return 0;
> -		}
> +		if (!ex)
> +			goto cleanup;
> +
>  		cur = max(cur + 1, le32_to_cpu(ex->ee_block) +
>  					ext4_ext_get_actual_len(ex));
>  		ret = skip_hole(inode, &cur);
> -		if (ret < 0) {
> -			ext4_free_ext_path(path);
> +		if (ret < 0)
>  			break;
> -		}
> -		path2 = ext4_find_extent(inode, cur, NULL, 0);
> -		if (IS_ERR(path2)) {
> -			ext4_free_ext_path(path);
> +
> +		path2 = ext4_find_extent(inode, cur, path2, 0);
> +		if (IS_ERR(path2))
>  			break;
> -		}
> +
>  		for (i = 0; i <= max(path->p_depth, path2->p_depth); i++) {
>  			cmp1 = cmp2 = 0;
>  			if (i <= path->p_depth)
> @@ -6136,13 +6129,14 @@ int ext4_ext_replay_set_iblocks(struct inode *inode)
>  			if (cmp1 != cmp2 && cmp2 != 0)
>  				numblks++;
>  		}
> -		ext4_free_ext_path(path);
> -		ext4_free_ext_path(path2);
>  	}
>  
>  out:
>  	inode->i_blocks = numblks << (inode->i_sb->s_blocksize_bits - 9);
>  	ext4_mark_inode_dirty(NULL, inode);
> +cleanup:
> +	ext4_free_ext_path(path);
> +	ext4_free_ext_path(path2);
>  	return 0;
>  }
>  
> @@ -6163,12 +6157,9 @@ int ext4_ext_clear_bb(struct inode *inode)
>  	if (IS_ERR(path))
>  		return PTR_ERR(path);
>  	ex = path[path->p_depth].p_ext;
> -	if (!ex) {
> -		ext4_free_ext_path(path);
> -		return 0;
> -	}
> +	if (!ex)
> +		goto out;
>  	end = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
> -	ext4_free_ext_path(path);
>  
>  	cur = 0;
>  	while (cur < end) {
> @@ -6178,16 +6169,16 @@ int ext4_ext_clear_bb(struct inode *inode)
>  		if (ret < 0)
>  			break;
>  		if (ret > 0) {
> -			path = ext4_find_extent(inode, map.m_lblk, NULL, 0);
> -			if (!IS_ERR_OR_NULL(path)) {
> +			path = ext4_find_extent(inode, map.m_lblk, path, 0);
> +			if (!IS_ERR(path)) {
>  				for (j = 0; j < path->p_depth; j++) {
> -
>  					ext4_mb_mark_bb(inode->i_sb,
>  							path[j].p_block, 1, false);
>  					ext4_fc_record_regions(inode->i_sb, inode->i_ino,
>  							0, path[j].p_block, 1, 1);
>  				}
> -				ext4_free_ext_path(path);
> +			} else {
> +				path = NULL;
>  			}
>  			ext4_mb_mark_bb(inode->i_sb, map.m_pblk, map.m_len, false);
>  			ext4_fc_record_regions(inode->i_sb, inode->i_ino,
> @@ -6196,5 +6187,7 @@ int ext4_ext_clear_bb(struct inode *inode)
>  		cur = cur + map.m_len;
>  	}
>  
> +out:
> +	ext4_free_ext_path(path);
>  	return 0;
>  }
> diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> index 1dee40477727..1426d595fab7 100644
> --- a/fs/ext4/fast_commit.c
> +++ b/fs/ext4/fast_commit.c
> @@ -1766,7 +1766,7 @@ static int ext4_fc_replay_add_range(struct super_block *sb,
>  
>  		if (ret == 0) {
>  			/* Range is not mapped */
> -			path = ext4_find_extent(inode, cur, NULL, 0);
> +			path = ext4_find_extent(inode, cur, path, 0);
>  			if (IS_ERR(path))
>  				goto out;
>  			memset(&newex, 0, sizeof(newex));
> @@ -1782,7 +1782,6 @@ static int ext4_fc_replay_add_range(struct super_block *sb,
>  			up_write((&EXT4_I(inode)->i_data_sem));
>  			if (IS_ERR(path))
>  				goto out;
> -			ext4_free_ext_path(path);
>  			goto next;
>  		}
>  
> @@ -1830,6 +1829,7 @@ static int ext4_fc_replay_add_range(struct super_block *sb,
>  	ext4_ext_replay_shrink_inode(inode, i_size_read(inode) >>
>  					sb->s_blocksize_bits);
>  out:
> +	ext4_free_ext_path(path);
>  	iput(inode);
>  	return 0;
>  }
> @@ -1930,12 +1930,13 @@ static void ext4_fc_set_bitmaps_and_counters(struct super_block *sb)
>  				break;
>  
>  			if (ret > 0) {
> -				path = ext4_find_extent(inode, map.m_lblk, NULL, 0);
> +				path = ext4_find_extent(inode, map.m_lblk, path, 0);
>  				if (!IS_ERR(path)) {
>  					for (j = 0; j < path->p_depth; j++)
>  						ext4_mb_mark_bb(inode->i_sb,
>  							path[j].p_block, 1, true);
> -					ext4_free_ext_path(path);
> +				} else {
> +					path = NULL;
>  				}
>  				cur += ret;
>  				ext4_mb_mark_bb(inode->i_sb, map.m_pblk,
> @@ -1946,6 +1947,8 @@ static void ext4_fc_set_bitmaps_and_counters(struct super_block *sb)
>  		}
>  		iput(inode);
>  	}
> +
> +	ext4_free_ext_path(path);
>  }
>  
>  /*
> -- 
> 2.39.2
> 

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