linux-kernel - Re: [RFC PATCH] vfat:avoid unnecessary check

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Message-ID: <87bjnqkpns.fsf@mail.parknet.co.jp>
Date: Fri, 05 Sep 2025 04:01:43 +0900
From: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To: zhoumin <teczm@...mail.com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] vfat:avoid unnecessary check

zhoumin <teczm@...mail.com> writes:

> Remove redundant and unreachable name check code in dir.c.

Looks like you changed the logic, but no explanation.

> Remove flags check in fat_update_time since fat does not support
> inode version.
>
> Optimize fat_truncate_time to return a meaningful value, allowing
> the removal of redundant inode checks in fat_update_time. This
> ensures non-root inodes are validated only once.

Also changed the logic, you removed the check of flags.

The change may not have the issue, however please change and explain
more carefully.

Thanks.

> Signed-off-by: zhoumin <teczm@...mail.com>
> ---
>  fs/fat/dir.c  | 12 ++++--------
>  fs/fat/misc.c | 11 ++++-------
>  2 files changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/fs/fat/dir.c b/fs/fat/dir.c
> index acbec5bdd521..4f1be9939292 100644
> --- a/fs/fat/dir.c
> +++ b/fs/fat/dir.c
> @@ -337,11 +337,11 @@ static int fat_parse_long(struct inode *dir, loff_t *pos,
>  		if (ds->alias_checksum != alias_checksum)
>  			goto parse_long;
>  	}
> -	if ((*de)->name[0] == DELETED_FLAG)
> +	if (IS_FREE((*de)->name))
>  		return PARSE_INVALID;
>  	if ((*de)->attr == ATTR_EXT)
>  		goto parse_long;
> -	if (IS_FREE((*de)->name) || ((*de)->attr & ATTR_VOLUME))
> +	if ((*de)->attr & ATTR_VOLUME)
>  		return PARSE_INVALID;
>  	if (fat_checksum((*de)->name) != alias_checksum)
>  		*nr_slots = 0;
> @@ -491,12 +491,10 @@ int fat_search_long(struct inode *inode, const unsigned char *name,
>  			goto end_of_dir;
>  parse_record:
>  		nr_slots = 0;
> -		if (de->name[0] == DELETED_FLAG)
> +		if (IS_FREE(de->name))
>  			continue;
>  		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
>  			continue;
> -		if (de->attr != ATTR_EXT && IS_FREE(de->name))
> -			continue;
>  		if (de->attr == ATTR_EXT) {
>  			int status = fat_parse_long(inode, &cpos, &bh, &de,
>  						    &unicode, &nr_slots);
> @@ -608,12 +606,10 @@ static int __fat_readdir(struct inode *inode, struct file *file,
>  	 * need to parse long filename.
>  	 */
>  	if (isvfat && !short_only) {
> -		if (de->name[0] == DELETED_FLAG)
> +		if (IS_FREE(de->name))
>  			goto record_end;
>  		if (de->attr != ATTR_EXT && (de->attr & ATTR_VOLUME))
>  			goto record_end;
> -		if (de->attr != ATTR_EXT && IS_FREE(de->name))
> -			goto record_end;
>  	} else {
>  		if ((de->attr & ATTR_VOLUME) || IS_FREE(de->name))
>  			goto record_end;
> diff --git a/fs/fat/misc.c b/fs/fat/misc.c
> index c7a2d27120ba..41f6362a0428 100644
> --- a/fs/fat/misc.c
> +++ b/fs/fat/misc.c
> @@ -335,7 +335,7 @@ int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
>  		inode_set_mtime_to_ts(inode,
>  				      inode_set_ctime_to_ts(inode, fat_truncate_mtime(sbi, now)));
>  
> -	return 0;
> +	return 1;
>  }
>  EXPORT_SYMBOL_GPL(fat_truncate_time);
>  
> @@ -343,18 +343,15 @@ int fat_update_time(struct inode *inode, int flags)
>  {
>  	int dirty_flags = 0;
>  
> -	if (inode->i_ino == MSDOS_ROOT_INO)
> -		return 0;
> -
> -	if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
> -		fat_truncate_time(inode, NULL, flags);
> +	if (fat_truncate_time(inode, NULL, flags)) {
>  		if (inode->i_sb->s_flags & SB_LAZYTIME)
>  			dirty_flags |= I_DIRTY_TIME;
>  		else
>  			dirty_flags |= I_DIRTY_SYNC;
> +
> +		__mark_inode_dirty(inode, dirty_flags);
>  	}
>  
> -	__mark_inode_dirty(inode, dirty_flags);
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(fat_update_time);

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