linux-kernel - Re: [PATCH v2 2/2] fat: always use dir_emit

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Date: Wed, 26 Jun 2024 06:47:15 +0900
From: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To: Thadeu Lima de Souza Cascardo <cascardo@...lia.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Gwendal
 Grignou <gwendal@...omium.org>, dlunev@...omium.org
Subject: Re: [PATCH v2 2/2] fat: always use dir_emit_dots and ignore . and
 .. entries

Thadeu Lima de Souza Cascardo <cascardo@...lia.com> writes:

> Instead of only using dir_emit_dots for the root inode and explictily
> requiring the . and .. entries to emit them, use dir_emit_dots for all
> directories.
>
> That allows filesystems with directories without the . or .. entries to
> still show them.

Unacceptable to change the correct behavior to broken format. And
unlikely break the userspace, however this still has the user visible
change of seek pos.

Thanks.

> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...lia.com>
> ---
>  fs/fat/dir.c | 24 +++++++++---------------
>  1 file changed, 9 insertions(+), 15 deletions(-)
>
> diff --git a/fs/fat/dir.c b/fs/fat/dir.c
> index 4e4a359a1ea3..e70781569de5 100644
> --- a/fs/fat/dir.c
> +++ b/fs/fat/dir.c
> @@ -583,15 +583,14 @@ static int __fat_readdir(struct inode *inode, struct file *file,
>  	mutex_lock(&sbi->s_lock);
>  
>  	cpos = ctx->pos;
> -	/* Fake . and .. for the root directory. */
> -	if (inode->i_ino == MSDOS_ROOT_INO) {
> -		if (!dir_emit_dots(file, ctx))
> -			goto out;
> -		if (ctx->pos == 2) {
> -			fake_offset = 1;
> -			cpos = 0;
> -		}
> +
> +	if (!dir_emit_dots(file, ctx))
> +		goto out;
> +	if (ctx->pos == 2) {
> +		fake_offset = 1;
> +		cpos = 0;
>  	}
> +
>  	if (cpos & (sizeof(struct msdos_dir_entry) - 1)) {
>  		ret = -ENOENT;
>  		goto out;
> @@ -671,13 +670,8 @@ static int __fat_readdir(struct inode *inode, struct file *file,
>  	if (fake_offset && ctx->pos < 2)
>  		ctx->pos = 2;
>  
> -	if (!memcmp(de->name, MSDOS_DOT, MSDOS_NAME)) {
> -		if (!dir_emit_dot(file, ctx))
> -			goto fill_failed;
> -	} else if (!memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
> -		if (!dir_emit_dotdot(file, ctx))
> -			goto fill_failed;
> -	} else {
> +	if (memcmp(de->name, MSDOS_DOT, MSDOS_NAME) &&
> +	    memcmp(de->name, MSDOS_DOTDOT, MSDOS_NAME)) {
>  		unsigned long inum;
>  		loff_t i_pos = fat_make_i_pos(sb, bh, de);
>  		struct inode *tmp = fat_iget(sb, i_pos);

-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>