Chung-Chiang Cheng <cccheng@xxxxxxxxxxxx> writes:
> FAT supports creation time but not change time, and there was no
> corresponding timestamp for creation time in previous VFS. The
> original implementation took the compromise of saving the in-memory
> change time into the on-disk creation time field, but this would lead
> to compatibility issues with non-linux systems.
>
> To address this issue, this patch changes the behavior of ctime. It
> will no longer be loaded and stored from the creation time on disk.
> Instead of that, it'll be consistent with the in-memory mtime and share
> the same on-disk field. All updates to mtime will also be applied to
> ctime in memory, while all updates to ctime will be ignored.
Acked-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Thanks.
> Signed-off-by: Chung-Chiang Cheng <cccheng@xxxxxxxxxxxx>
> ---
> fs/fat/inode.c | 11 ++++-------
> fs/fat/misc.c | 9 ++++++---
> 2 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
> index bf6051bdf1d1..16d5a52116d3 100644
> --- a/fs/fat/inode.c
> +++ b/fs/fat/inode.c
> @@ -567,12 +567,11 @@ int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
> & ~((loff_t)sbi->cluster_size - 1)) >> 9;
>
> fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
> - if (sbi->options.isvfat) {
> - fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
> - de->cdate, de->ctime_cs);
> + inode->i_ctime = inode->i_mtime;
> + if (sbi->options.isvfat)
> fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
> - } else
> - fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
> + else
> + inode->i_atime = fat_truncate_atime(sbi, &inode->i_mtime);
>
> return 0;
> }
> @@ -888,8 +887,6 @@ static int __fat_write_inode(struct inode *inode, int wait)
> &raw_entry->date, NULL);
> if (sbi->options.isvfat) {
> __le16 atime;
> - fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
> - &raw_entry->cdate, &raw_entry->ctime_cs);
> fat_time_unix2fat(sbi, &inode->i_atime, &atime,
> &raw_entry->adate, NULL);
> }
> diff --git a/fs/fat/misc.c b/fs/fat/misc.c
> index 63160e47be00..85bb9dc3af2d 100644
> --- a/fs/fat/misc.c
> +++ b/fs/fat/misc.c
> @@ -341,10 +341,13 @@ int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
>
> if (flags & S_ATIME)
> inode->i_atime = fat_truncate_atime(sbi, now);
> - if (flags & S_CTIME)
> - inode->i_ctime = fat_truncate_crtime(sbi, now);
> + /*
> + * ctime and mtime share the same on-disk field, and should be
> + * identical in memory. all mtime updates will be applied to ctime,
> + * but ctime updates are ignored.
> + */
> if (flags & S_MTIME)
> - inode->i_mtime = fat_truncate_mtime(sbi, now);
> + inode->i_mtime = inode->i_ctime = fat_truncate_mtime(sbi, now);
>
> return 0;
> }
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
