Commit 3aa63a56 authored by Jeff Layton's avatar Jeff Layton Committed by Christian Brauner
Browse files

fs: switch timespec64 fields in inode to discrete integers 



Adjacent struct timespec64's pack poorly. Switch them to discrete
integer fields for the seconds and nanoseconds. This shaves 8 bytes off
struct inode with a garden-variety Fedora Kconfig on x86_64, but that
also moves the i_lock into the previous cacheline, away from the fields
it protects.

To remedy that, move i_generation above the i_lock, which moves the new
4-byte hole to just after the i_fsnotify_mask in my setup. Amir has
plans to use that to expand the i_fsnotify_mask, so add a comment to
that effect as well.

Cc: Amir Goldstein <amir73il@gmail.com>
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240517-amtime-v1-1-7b804ca4be8f@kernel.org


Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 23cc6ef6

include/linux/fs.h

+32 −16
Original line number Diff line number Diff line
@@ -660,9 +660,13 @@ struct inode { 
	};

	dev_t			i_rdev;

	loff_t			i_size;

	struct timespec64	__i_atime;

	struct timespec64	__i_mtime;

	struct timespec64	__i_ctime; /* use inode_*_ctime accessors! */

	time64_t		i_atime_sec;

	time64_t		i_mtime_sec;

	time64_t		i_ctime_sec;

	u32			i_atime_nsec;

	u32			i_mtime_nsec;

	u32			i_ctime_nsec;

	u32			i_generation;

	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */

	unsigned short          i_bytes;

	u8			i_blkbits;
@@ -719,10 +723,10 @@ struct inode { 
		unsigned		i_dir_seq;

	};



	__u32			i_generation;



#ifdef CONFIG_FSNOTIFY

	__u32			i_fsnotify_mask; /* all events this inode cares about */

	/* 32-bit hole reserved for expanding i_fsnotify_mask */

	struct fsnotify_mark_connector __rcu	*i_fsnotify_marks;

#endif
@@ -1538,23 +1542,27 @@ struct timespec64 inode_set_ctime_current(struct inode *inode); 


static inline time64_t inode_get_atime_sec(const struct inode *inode)

{

	return inode->__i_atime.tv_sec;

	return inode->i_atime_sec;

}



static inline long inode_get_atime_nsec(const struct inode *inode)

{

	return inode->__i_atime.tv_nsec;

	return inode->i_atime_nsec;

}



static inline struct timespec64 inode_get_atime(const struct inode *inode)

{

	return inode->__i_atime;

	struct timespec64 ts = { .tv_sec  = inode_get_atime_sec(inode),

				 .tv_nsec = inode_get_atime_nsec(inode) };



	return ts;

}



static inline struct timespec64 inode_set_atime_to_ts(struct inode *inode,

						      struct timespec64 ts)

{

	inode->__i_atime = ts;

	inode->i_atime_sec = ts.tv_sec;

	inode->i_atime_nsec = ts.tv_nsec;

	return ts;

}
@@ -1563,28 +1571,32 @@ static inline struct timespec64 inode_set_atime(struct inode *inode, 
{

	struct timespec64 ts = { .tv_sec  = sec,

				 .tv_nsec = nsec };



	return inode_set_atime_to_ts(inode, ts);

}



static inline time64_t inode_get_mtime_sec(const struct inode *inode)

{

	return inode->__i_mtime.tv_sec;

	return inode->i_mtime_sec;

}



static inline long inode_get_mtime_nsec(const struct inode *inode)

{

	return inode->__i_mtime.tv_nsec;

	return inode->i_mtime_nsec;

}



static inline struct timespec64 inode_get_mtime(const struct inode *inode)

{

	return inode->__i_mtime;

	struct timespec64 ts = { .tv_sec  = inode_get_mtime_sec(inode),

				 .tv_nsec = inode_get_mtime_nsec(inode) };

	return ts;

}



static inline struct timespec64 inode_set_mtime_to_ts(struct inode *inode,

						      struct timespec64 ts)

{

	inode->__i_mtime = ts;

	inode->i_mtime_sec = ts.tv_sec;

	inode->i_mtime_nsec = ts.tv_nsec;

	return ts;

}
@@ -1598,23 +1610,27 @@ static inline struct timespec64 inode_set_mtime(struct inode *inode, 


static inline time64_t inode_get_ctime_sec(const struct inode *inode)

{

	return inode->__i_ctime.tv_sec;

	return inode->i_ctime_sec;

}



static inline long inode_get_ctime_nsec(const struct inode *inode)

{

	return inode->__i_ctime.tv_nsec;

	return inode->i_ctime_nsec;

}



static inline struct timespec64 inode_get_ctime(const struct inode *inode)

{

	return inode->__i_ctime;

	struct timespec64 ts = { .tv_sec  = inode_get_ctime_sec(inode),

				 .tv_nsec = inode_get_ctime_nsec(inode) };



	return ts;

}



static inline struct timespec64 inode_set_ctime_to_ts(struct inode *inode,

						      struct timespec64 ts)

{

	inode->__i_ctime = ts;

	inode->i_ctime_sec = ts.tv_sec;

	inode->i_ctime_nsec = ts.tv_nsec;

	return ts;

}