linux-kernel - Re: [PATCH RFC 2/7] libfs: Define a minimum directory offset

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Message-ID: <20240215124716.a7vdfjcnntyc6qj6@quack3>
Date: Thu, 15 Feb 2024 13:47:16 +0100
From: Jan Kara <jack@...e.cz>
To: Chuck Lever <cel@...nel.org>
Cc: viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
	hughd@...gle.com, akpm@...ux-foundation.org,
	Liam.Howlett@...cle.com, oliver.sang@...el.com, feng.tang@...el.com,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	maple-tree@...ts.infradead.org, linux-mm@...ck.org, lkp@...el.com
Subject: Re: [PATCH RFC 2/7] libfs: Define a minimum directory offset

On Tue 13-02-24 16:37:32, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@...cle.com>
> 
> This value is used in several places, so make it a symbolic
> constant.
> 
> Signed-off-by: Chuck Lever <chuck.lever@...cle.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  fs/libfs.c |   13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/libfs.c b/fs/libfs.c
> index bfbe1a8c5d2d..a38af72f4719 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -240,6 +240,11 @@ const struct inode_operations simple_dir_inode_operations = {
>  };
>  EXPORT_SYMBOL(simple_dir_inode_operations);
>  
> +/* 0 is '.', 1 is '..', so always start with offset 2 or more */
> +enum {
> +	DIR_OFFSET_MIN	= 2,
> +};
> +
>  static void offset_set(struct dentry *dentry, u32 offset)
>  {
>  	dentry->d_fsdata = (void *)((uintptr_t)(offset));
> @@ -261,9 +266,7 @@ void simple_offset_init(struct offset_ctx *octx)
>  {
>  	xa_init_flags(&octx->xa, XA_FLAGS_ALLOC1);
>  	lockdep_set_class(&octx->xa.xa_lock, &simple_offset_xa_lock);
> -
> -	/* 0 is '.', 1 is '..', so always start with offset 2 */
> -	octx->next_offset = 2;
> +	octx->next_offset = DIR_OFFSET_MIN;
>  }
>  
>  /**
> @@ -276,7 +279,7 @@ void simple_offset_init(struct offset_ctx *octx)
>   */
>  int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry)
>  {
> -	static const struct xa_limit limit = XA_LIMIT(2, U32_MAX);
> +	static const struct xa_limit limit = XA_LIMIT(DIR_OFFSET_MIN, U32_MAX);
>  	u32 offset;
>  	int ret;
>  
> @@ -481,7 +484,7 @@ static int offset_readdir(struct file *file, struct dir_context *ctx)
>  		return 0;
>  
>  	/* In this case, ->private_data is protected by f_pos_lock */
> -	if (ctx->pos == 2)
> +	if (ctx->pos == DIR_OFFSET_MIN)
>  		file->private_data = NULL;
>  	else if (file->private_data == ERR_PTR(-ENOENT))
>  		return 0;
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR