Re: [PATCH 2/2 V2] exfat: truncate atimes to 2s granularity

[Namjae Jeon <linkinjeon@kernel.org>]

2020-04-16 13:11 GMT+09:00, Eric Sandeen <sandeen@sandeen.net>:
Hi Eric,

> exfat atimes are restricted to only 2s granularity so after
> we set an atime, round it down to the nearest 2s and set the
> sub-second component of the timestamp to 0.
Is there any reason why only atime is truncated with 2s granularity ?

Thanks.
>
> Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
> ---
>
> V2: don't just zero tv_nsec, must also round down tv_sec I think.
>
> diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
> index 67d4e46fb810..d67fb8a6f770 100644
> --- a/fs/exfat/exfat_fs.h
> +++ b/fs/exfat/exfat_fs.h
> @@ -507,6 +507,7 @@ void exfat_msg(struct super_block *sb, const char *lv,
> const char *fmt, ...)
>  		__printf(3, 4) __cold;
>  void exfat_get_entry_time(struct exfat_sb_info *sbi, struct timespec64
> *ts,
>  		u8 tz, __le16 time, __le16 date, u8 time_ms);
> +void exfat_truncate_atime(struct timespec64 *ts);
>  void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64
> *ts,
>  		u8 *tz, __le16 *time, __le16 *date, u8 *time_ms);
>  unsigned short exfat_calc_chksum_2byte(void *data, int len,
> diff --git a/fs/exfat/file.c b/fs/exfat/file.c
> index 483f683757aa..4f76764165cf 100644
> --- a/fs/exfat/file.c
> +++ b/fs/exfat/file.c
> @@ -273,6 +273,7 @@ int exfat_getattr(const struct path *path, struct kstat
> *stat,
>  	struct exfat_inode_info *ei = EXFAT_I(inode);
>
>  	generic_fillattr(inode, stat);
> +	exfat_truncate_atime(&stat->atime);
>  	stat->result_mask |= STATX_BTIME;
>  	stat->btime.tv_sec = ei->i_crtime.tv_sec;
>  	stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
> @@ -339,6 +340,7 @@ int exfat_setattr(struct dentry *dentry, struct iattr
> *attr)
>  	}
>
>  	setattr_copy(inode, attr);
> +	exfat_truncate_atime(&inode->i_atime);
>  	mark_inode_dirty(inode);
>
>  out:
> diff --git a/fs/exfat/misc.c b/fs/exfat/misc.c
> index 14a3300848f6..c8b33278d474 100644
> --- a/fs/exfat/misc.c
> +++ b/fs/exfat/misc.c
> @@ -88,7 +88,8 @@ void exfat_get_entry_time(struct exfat_sb_info *sbi,
> struct timespec64 *ts,
>  	if (time_ms) {
>  		ts->tv_sec += time_ms / 100;
>  		ts->tv_nsec = (time_ms % 100) * 10 * NSEC_PER_MSEC;
> -	}
> +	} else
> +		exfat_truncate_atime(ts);
>
>  	if (tz & EXFAT_TZ_VALID)
>  		/* Adjust timezone to UTC0. */
> @@ -124,6 +125,13 @@ void exfat_set_entry_time(struct exfat_sb_info *sbi,
> struct timespec64 *ts,
>  	*tz = EXFAT_TZ_VALID;
>  }
>
> +/* atime has only a 2-second resolution */
> +void exfat_truncate_atime(struct timespec64 *ts)
> +{
> +	ts->tv_sec = round_down(ts->tv_sec, 2);
> +	ts->tv_nsec = 0;
> +}
> +
>  unsigned short exfat_calc_chksum_2byte(void *data, int len,
>  		unsigned short chksum, int type)
>  {
> diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
> index a8681d91f569..b72d782568b8 100644
> --- a/fs/exfat/namei.c
> +++ b/fs/exfat/namei.c
> @@ -595,6 +595,7 @@ static int exfat_create(struct inode *dir, struct dentry
> *dentry, umode_t mode,
>  	inode_inc_iversion(inode);
>  	inode->i_mtime = inode->i_atime = inode->i_ctime =
>  		EXFAT_I(inode)->i_crtime = current_time(inode);
> +	exfat_truncate_atime(&inode->i_atime);
>  	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
>
>  	d_instantiate(dentry, inode);
> @@ -854,6 +855,7 @@ static int exfat_unlink(struct inode *dir, struct dentry
> *dentry)
>
>  	inode_inc_iversion(dir);
>  	dir->i_mtime = dir->i_atime = current_time(dir);
> +	exfat_truncate_atime(&dir->i_atime);
>  	if (IS_DIRSYNC(dir))
>  		exfat_sync_inode(dir);
>  	else
> @@ -861,6 +863,7 @@ static int exfat_unlink(struct inode *dir, struct dentry
> *dentry)
>
>  	clear_nlink(inode);
>  	inode->i_mtime = inode->i_atime = current_time(inode);
> +	exfat_truncate_atime(&inode->i_atime);
>  	exfat_unhash_inode(inode);
>  	exfat_d_version_set(dentry, inode_query_iversion(dir));
>  unlock:
> @@ -903,6 +906,7 @@ static int exfat_mkdir(struct inode *dir, struct dentry
> *dentry, umode_t mode)
>  	inode_inc_iversion(inode);
>  	inode->i_mtime = inode->i_atime = inode->i_ctime =
>  		EXFAT_I(inode)->i_crtime = current_time(inode);
> +	exfat_truncate_atime(&inode->i_atime);
>  	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
>
>  	d_instantiate(dentry, inode);
> @@ -1019,6 +1023,7 @@ static int exfat_rmdir(struct inode *dir, struct
> dentry *dentry)
>
>  	inode_inc_iversion(dir);
>  	dir->i_mtime = dir->i_atime = current_time(dir);
> +	exfat_truncate_atime(&dir->i_atime);
>  	if (IS_DIRSYNC(dir))
>  		exfat_sync_inode(dir);
>  	else
> @@ -1027,6 +1032,7 @@ static int exfat_rmdir(struct inode *dir, struct
> dentry *dentry)
>
>  	clear_nlink(inode);
>  	inode->i_mtime = inode->i_atime = current_time(inode);
> +	exfat_truncate_atime(&inode->i_atime);
>  	exfat_unhash_inode(inode);
>  	exfat_d_version_set(dentry, inode_query_iversion(dir));
>  unlock:
> @@ -1387,6 +1393,7 @@ static int exfat_rename(struct inode *old_dir, struct
> dentry *old_dentry,
>  	inode_inc_iversion(new_dir);
>  	new_dir->i_ctime = new_dir->i_mtime = new_dir->i_atime =
>  		EXFAT_I(new_dir)->i_crtime = current_time(new_dir);
> +	exfat_truncate_atime(&new_dir->i_atime);
>  	if (IS_DIRSYNC(new_dir))
>  		exfat_sync_inode(new_dir);
>  	else
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c
> index 16ed202ef527..aed62cafb0da 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -351,6 +351,7 @@ static int exfat_read_root(struct inode *inode)
>  	exfat_save_attr(inode, ATTR_SUBDIR);
>  	inode->i_mtime = inode->i_atime = inode->i_ctime = ei->i_crtime =
>  		current_time(inode);
> +	exfat_truncate_atime(&inode->i_atime);
>  	exfat_cache_init_inode(inode);
>  	return 0;
>  }
>
>