| Message ID | 866cd645-3e99-c7a5-56d6-9134a03c556d@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Frank Sorenson <sorenson@redhat.com> writes: Hi, > Author: Frank Sorenson <sorenson@redhat.com> > Date: 2018-03-23 23:28:32 -0500 > > fat: add function to truncate timestamps returned from fat_getattr > > vfat/msdos timestamps are stored on-disk with several different > granularities, some of them lower resolution than timespec_trunc() > can provide. However, they are only truncated as they are written > to disk, so the timestamps in-memory for new or modified > files/directories may be different from the same timestamps after > a remount, as the now-truncated times are re-read from the on-disk > format. > > This patch adds a function to adjust the timestamps returned from > fat_getattr() so that userspace sees consistent times across a > remount. The existing functions are used to convert the timespec > to the on-disk representation, then back to timespec again. > > Signed-off-by: Frank Sorenson <sorenson@redhat.com> Already tried to use ->update_time() callback? With quick look though, it seems to be possible to control timestamp granularity with ->update_time(), and add fat_current_time() or such to get proper timestamp for FAT. I think we should give consistent in-core inode timestamp too. For example, overlayfs may be copy timestamps from in-core inode, etc., then this stat workaround will not work. Thanks. > diff --git a/fs/fat/fat.h b/fs/fat/fat.h > index 8fc1093da47d..0367be021b23 100644 > --- a/fs/fat/fat.h > +++ b/fs/fat/fat.h > @@ -410,6 +410,7 @@ extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts, > __le16 __time, __le16 __date, u8 time_cs); > extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts, > __le16 *time, __le16 *date, u8 *time_cs); > +extern void fat_trunc_kstat_times(struct msdos_sb_info *sbi, struct kstat *stat); > extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs); > > int fat_cache_init(void); > diff --git a/fs/fat/file.c b/fs/fat/file.c > index 4724cc9ad650..11639e393ef7 100644 > --- a/fs/fat/file.c > +++ b/fs/fat/file.c > @@ -370,6 +370,7 @@ int fat_getattr(const struct path *path, struct kstat *stat, > { > struct inode *inode = d_inode(path->dentry); > generic_fillattr(inode, stat); > + fat_trunc_kstat_times(MSDOS_SB(inode->i_sb), stat); > stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size; > > if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) { > diff --git a/fs/fat/misc.c b/fs/fat/misc.c > index f9bdc1e01c98..52f40edefd12 100644 > --- a/fs/fat/misc.c > +++ b/fs/fat/misc.c > @@ -262,6 +262,29 @@ void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts, > } > EXPORT_SYMBOL_GPL(fat_time_unix2fat); > > +void fat_trunc_kstat_times(struct msdos_sb_info *sbi, struct kstat *stat) > +{ > + if (stat->ino == MSDOS_ROOT_INO) > + stat->mtime = stat->ctime = stat->atime = > + (struct timespec){0, 0}; > + else { > + __le16 time; > + __le16 date; > + u8 ctime_cs; > + > + fat_time_unix2fat(sbi, &stat->mtime, &time, &date, NULL); > + fat_time_fat2unix(sbi, &stat->mtime, time, date, 0); > + > + fat_time_unix2fat(sbi, &stat->ctime, &time, &date, > + sbi->options.isvfat ? &ctime_cs : NULL); > + fat_time_fat2unix(sbi, &stat->ctime, time, date, > + sbi->options.isvfat ? ctime_cs : 0); > + > + fat_time_unix2fat(sbi, &stat->atime, &time, &date, NULL); > + fat_time_fat2unix(sbi, &stat->atime, 0, date, 0); > + } > +} > + > int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) > { > int i, err = 0;
On 04/01/2018 01:02 AM, OGAWA Hirofumi wrote: > Frank Sorenson <sorenson@redhat.com> writes: > > Already tried to use ->update_time() callback? With quick look though, > it seems to be possible to control timestamp granularity with > ->update_time(), and add fat_current_time() or such to get proper > timestamp for FAT. > > I think we should give consistent in-core inode timestamp too. For > example, overlayfs may be copy timestamps from in-core inode, etc., then > this stat workaround will not work. I'll see what I can do with update_time. Thanks. Frank
diff --git a/fs/fat/fat.h b/fs/fat/fat.h index 8fc1093da47d..0367be021b23 100644 --- a/fs/fat/fat.h +++ b/fs/fat/fat.h @@ -410,6 +410,7 @@ extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts, __le16 __time, __le16 __date, u8 time_cs); extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts, __le16 *time, __le16 *date, u8 *time_cs); +extern void fat_trunc_kstat_times(struct msdos_sb_info *sbi, struct kstat *stat); extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs); int fat_cache_init(void); diff --git a/fs/fat/file.c b/fs/fat/file.c index 4724cc9ad650..11639e393ef7 100644 --- a/fs/fat/file.c +++ b/fs/fat/file.c @@ -370,6 +370,7 @@ int fat_getattr(const struct path *path, struct kstat *stat, { struct inode *inode = d_inode(path->dentry); generic_fillattr(inode, stat); + fat_trunc_kstat_times(MSDOS_SB(inode->i_sb), stat); stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size; if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) { diff --git a/fs/fat/misc.c b/fs/fat/misc.c index f9bdc1e01c98..52f40edefd12 100644 --- a/fs/fat/misc.c +++ b/fs/fat/misc.c @@ -262,6 +262,29 @@ void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts, } EXPORT_SYMBOL_GPL(fat_time_unix2fat); +void fat_trunc_kstat_times(struct msdos_sb_info *sbi, struct kstat *stat) +{ + if (stat->ino == MSDOS_ROOT_INO) + stat->mtime = stat->ctime = stat->atime = + (struct timespec){0, 0}; + else { + __le16 time; + __le16 date; + u8 ctime_cs; + + fat_time_unix2fat(sbi, &stat->mtime, &time, &date, NULL); + fat_time_fat2unix(sbi, &stat->mtime, time, date, 0); + + fat_time_unix2fat(sbi, &stat->ctime, &time, &date, + sbi->options.isvfat ? &ctime_cs : NULL); + fat_time_fat2unix(sbi, &stat->ctime, time, date, + sbi->options.isvfat ? ctime_cs : 0); + + fat_time_unix2fat(sbi, &stat->atime, &time, &date, NULL); + fat_time_fat2unix(sbi, &stat->atime, 0, date, 0); + } +} + int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) { int i, err = 0;
Author: Frank Sorenson <sorenson@redhat.com> Date: 2018-03-23 23:28:32 -0500 fat: add function to truncate timestamps returned from fat_getattr vfat/msdos timestamps are stored on-disk with several different granularities, some of them lower resolution than timespec_trunc() can provide. However, they are only truncated as they are written to disk, so the timestamps in-memory for new or modified files/directories may be different from the same timestamps after a remount, as the now-truncated times are re-read from the on-disk format. This patch adds a function to adjust the timestamps returned from fat_getattr() so that userspace sees consistent times across a remount. The existing functions are used to convert the timespec to the on-disk representation, then back to timespec again. Signed-off-by: Frank Sorenson <sorenson@redhat.com>