linux-kernel - Re: [PATCH] f2fs: don't traverse directory blocks after EOF

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Message-ID: <ZqKDnpzwX85RyGaa@google.com>
Date: Thu, 25 Jul 2024 16:55:58 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: don't traverse directory blocks after EOF

On 07/12, Chao Yu wrote:
> All directory blocks are within the scope of i_size, so let's limit
> the end_block to just check valid dirent blocks.

Do we really need this?

> 
> Meanwhile, it uses dir_blocks() instead of variable for cleanup in
> __f2fs_find_entry().
> 
> Signed-off-by: Chao Yu <chao@...nel.org>
> ---
>  fs/f2fs/dir.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index 02c9355176d3..d4591c215f07 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -305,18 +305,21 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir,
>  	int s = GET_DENTRY_SLOTS(fname->disk_name.len);
>  	unsigned int nbucket, nblock;
>  	unsigned int bidx, end_block;
> +	unsigned long last_block;
>  	struct page *dentry_page;
>  	struct f2fs_dir_entry *de = NULL;
>  	pgoff_t next_pgofs;
>  	bool room = false;
>  	int max_slots;
>  
> +	last_block = dir_blocks(dir);
>  	nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
>  	nblock = bucket_blocks(level);
>  
>  	bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
>  			       le32_to_cpu(fname->hash) % nbucket);
>  	end_block = bidx + nblock;
> +	end_block = min_t(unsigned int, end_block, last_block);
>  
>  	while (bidx < end_block) {
>  		/* no need to allocate new dentry pages to all the indices */
> @@ -361,7 +364,6 @@ struct f2fs_dir_entry *__f2fs_find_entry(struct inode *dir,
>  					 const struct f2fs_filename *fname,
>  					 struct page **res_page)
>  {
> -	unsigned long npages = dir_blocks(dir);
>  	struct f2fs_dir_entry *de = NULL;
>  	unsigned int max_depth;
>  	unsigned int level;
> @@ -373,7 +375,7 @@ struct f2fs_dir_entry *__f2fs_find_entry(struct inode *dir,
>  		goto out;
>  	}
>  
> -	if (npages == 0)
> +	if (dir_blocks(dir) == 0)
>  		goto out;
>  
>  	max_depth = F2FS_I(dir)->i_current_depth;
> -- 
> 2.40.1