Re: [PATCH v4 16/19] fs: only set S_VERSION when updating times if necessary

Jan Kara
2018-01-02T16:50:41Z

On Fri 22-12-17 07:05:53, Jeff Layton wrote:
> From: Jeff Layton <jlayton@redhat.com>
>
> We only really need to update i_version if someone has queried for it
> since we last incremented it. By doing that, we can avoid having to
> update the inode if the times haven't changed.
>
> If the times have changed, then we go ahead and forcibly increment the
> counter, under the assumption that we'll be going to the storage
> anyway, and the increment itself is relatively cheap.
>
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> ---
> fs/inode.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index 19e72f500f71..2fa920188759 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1635,17 +1635,21 @@ static int relatime_need_update(const struct path *path, struct inode *inode,
> int generic_update_time(struct inode *inode, struct timespec *time, int flags)
> {
> int iflags = I_DIRTY_TIME;
> + bool dirty = false;
>
> if (flags & S_ATIME)
> inode->i_atime = *time;
> if (flags & S_VERSION)
> - inode_inc_iversion(inode);
> + dirty |= inode_maybe_inc_iversion(inode, dirty);
> if (flags & S_CTIME)
> inode->i_ctime = *time;
> if (flags & S_MTIME)
> inode->i_mtime = *time;
> + if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
> + !(inode->i_sb->s_flags & SB_LAZYTIME))
> + dirty = true;

When you pass 'dirty' to inode_maybe_inc_iversion(), it is always false.
Maybe this condition should be at the beginning of the function? Once you
fix that the patch looks good so you can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR