The current representation of inode times in struct inode, struct iattr, and struct kstat use struct timespec. timespec is not y2038 safe.
Use struct inode_time for struct inode timestamp fields to maintain same size for times across 32 bit and 64 bit architectures. In addition, inode_time is defined as packed and aligned to a 4 byte boundary to make the structure use 12 bytes instead of 16 bytes. This will help save RAM space as inode structure is cached in memory. The other structures are transient and do not benefit from these changes. The pahole tool shows that this also uses up a 4 byte hole(on 64 bit arch) in the inode structure also contributing to space savings.
Add accessors for inode times. These provide a way to access the packed structure. Accessors abstract the timestamp representation so that any logic to convert between the struct inode timestamps and other interfaces can be placed here. This helps contain the inode_time structure within the context of struct inode.
The plan is to globally change all references to these types through these accessors only. So when the actual internal representation changes, it will be transparent to the outside world.
Add inode_timespec aliases to help convert kstat and iattr times to use 64 bit times. These hide the internal data type. Use uapi exposed data types here to keep minimal timstamp data type conversions in API's interfacing with vfs.
After the CONFIG_FS_USES_64BIT_TIME is enabled, all inode_timespec aliases will be removed and timespec64 data types and API's will be used directly.
Signed-off-by: Deepa Dinamani deepa.kernel@gmail.com --- include/linux/fs.h | 69 ++++++++++++++++++++++++++++++++++++++++++-------- include/linux/stat.h | 6 ++--- include/linux/time64.h | 35 +++++++++++++++++++++++++ 3 files changed, 97 insertions(+), 13 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h index 14ffad4..3b018c6 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -245,13 +245,13 @@ typedef void (dax_iodone_t)(struct buffer_head *bh_map, int uptodate); */ struct iattr { unsigned int ia_valid; - umode_t ia_mode; - kuid_t ia_uid; - kgid_t ia_gid; - loff_t ia_size; - struct timespec ia_atime; - struct timespec ia_mtime; - struct timespec ia_ctime; + umode_t ia_mode; + kuid_t ia_uid; + kgid_t ia_gid; + loff_t ia_size; + struct inode_timespec ia_atime; + struct inode_timespec ia_mtime; + struct inode_timespec ia_ctime;
/* * Not an attribute, but an auxiliary info for filesystems wanting to @@ -616,9 +616,9 @@ struct inode { }; dev_t i_rdev; loff_t i_size; - struct timespec i_atime; - struct timespec i_mtime; - struct timespec i_ctime; + struct inode_time i_atime; + struct inode_time i_mtime; + struct inode_time i_ctime; spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ unsigned short i_bytes; unsigned int i_blkbits; @@ -679,6 +679,55 @@ struct inode { void *i_private; /* fs or device private pointer */ };
+#ifdef CONFIG_FS_USES_64BIT_TIME + +#if __BITS_PER_LONG == 64 +static inline struct timespec64 +inode_get_inode_time(const struct inode_time *itime) +{ + return (struct timespec64) { + .tv_sec = itime->tv_sec; + .tv_nsec = itime->tv_nsec; + }; +} + +static inline void +inode_set_inode_time(struct inode_time *itime, const struct timespec64 ts64) +{ + itime->tv_sec = ts64.tv_sec; + itime->tv_nsec = ts64.tv_nsec; +} + +#else + +static inline struct timespec64 +inode_get_inode_time(const struct inode_time *itime) +{ + return *itime; +} + +static inline void +inode_set_inode_time(struct inode_time *itime, const struct timespec64 ts64) +{ + *itime = ts64; +} + +#endif +#else +static inline struct timespec +inode_get_inode_time(const struct timespec *itime) +{ + return *itime; +} + +static inline void +inode_set_inode_time(struct timespec *itime, const struct timespec ts) +{ + *itime = ts; +} + +#endif + static inline int inode_unhashed(struct inode *inode) { return hlist_unhashed(&inode->i_hash); diff --git a/include/linux/stat.h b/include/linux/stat.h index 075cb0c..559983f 100644 --- a/include/linux/stat.h +++ b/include/linux/stat.h @@ -27,9 +27,9 @@ struct kstat { kgid_t gid; dev_t rdev; loff_t size; - struct timespec atime; - struct timespec mtime; - struct timespec ctime; + struct inode_timespec atime; + struct inode_timespec mtime; + struct inode_timespec ctime; unsigned long blksize; unsigned long long blocks; }; diff --git a/include/linux/time64.h b/include/linux/time64.h index 367d5af..43ad63b 100644 --- a/include/linux/time64.h +++ b/include/linux/time64.h @@ -26,6 +26,41 @@ struct itimerspec64 {
#endif
+#ifdef CONFIG_FS_USES_64BIT_TIME + +/* + * Internal kernel representation of inode time fields. + * This structure is not exposed to userspace. + * Use struct timespec64 representation for all userspace. + */ +#if __BITS_PER_LONG == 64 +struct inode_time { + time64_t tv_sec; + s32 tv_nsec; +} __aligned(4) __packed; +#else +#define inode_time timespec64 +#endif +/* A place holder define until CONFIG_FS_USES_64BIT_TIME + * is enabled. + * timespec64 data type and functions will be used at that + * time directly and these defines will be deleted. + */ +#define inode_timespec timespec64 + +#define inode_timespec_compare timespec64_compare +#define inode_timespec_equal timespec64_equal + +#else +#define inode_time timespec + +#define inode_timespec timespec + +#define inode_timespec_compare timespec_compare +#define inode_timespec_equal timespec_equal + +#endif + /* Parameters used to convert the timespec values: */ #define MSEC_PER_SEC 1000L #define USEC_PER_MSEC 1000L