On Wed, Oct 4, 2023 at 9:56 PM Jeff Layton <[email protected]> wrote:
>
> The recent change to use discrete integers instead of struct timespec64
> shaved 8 bytes off of struct inode, but it also moves the i_lock
> into the previous cacheline, away from the fields that it protects.
>
> Move i_generation above the i_lock, which moves the new 4 byte hole to
> just after the i_fsnotify_mask in my setup.
Might be good to mention that this hole has a purpose...
>
> Suggested-by: Amir Goldstein <[email protected]>
> Signed-off-by: Jeff Layton <[email protected]>
> ---
> include/linux/fs.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 485b5e21c8e5..686c9f33e725 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -677,6 +677,7 @@ struct inode {
> 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;
> @@ -733,7 +734,6 @@ struct inode {
> unsigned i_dir_seq;
> };
>
> - __u32 i_generation;
>
> #ifdef CONFIG_FSNOTIFY
> __u32 i_fsnotify_mask; /* all events this inode cares about */
If you post another version, please leave a comment here
+ /* 32bit hole reserved for expanding i_fsnotify_mask to 64bit */
Thanks,
Amir.