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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Fri, 13 Apr 2018 17:02:00 +0300
Message-ID: <CAOQ4uxikOObrKptxGUFWkkko0LcaidYpVbDcVJJA3cFF8fwMAA@mail.gmail.com>
Subject: Re: [RFC PATCH 24/35] Revert "ovl: fix relatime for directories"
To:     Miklos Szeredi <mszeredi@redhat.com>
Cc:     overlayfs <linux-unionfs@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Thu, Apr 12, 2018 at 6:08 PM, Miklos Szeredi <mszeredi@redhat.com> wrote:
> This reverts commit cd91304e7190b4c4802f8e413ab2214b233e0260.
>
> Overlayfs no longer relies on the vfs correct atime handling.
>
> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> ---
>  fs/inode.c             | 21 ++++-----------------
>  fs/overlayfs/super.c   |  3 ---
>  include/linux/dcache.h |  3 ---
>  3 files changed, 4 insertions(+), 23 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index ef362364d396..163715de8cb2 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -1570,24 +1570,11 @@ EXPORT_SYMBOL(bmap);
>  static void update_ovl_inode_times(struct dentry *dentry, struct inode *inode,
>                                bool rcu)
>  {
> -       struct dentry *upperdentry;
> +       if (!rcu) {
> +               struct inode *realinode = d_real_inode(dentry);
>
> -       /*
> -        * Nothing to do if in rcu or if non-overlayfs
> -        */
> -       if (rcu || likely(!(dentry->d_flags & DCACHE_OP_REAL)))
> -               return;
> -
> -       upperdentry = d_real(dentry, NULL, 0, D_REAL_UPPER);
> -
> -       /*
> -        * If file is on lower then we can't update atime, so no worries about
> -        * stale mtime/ctime.
> -        */
> -       if (upperdentry) {
> -               struct inode *realinode = d_inode(upperdentry);
> -
> -               if ((!timespec_equal(&inode->i_mtime, &realinode->i_mtime) ||
> +               if (unlikely(inode != realinode) &&
> +                   (!timespec_equal(&inode->i_mtime, &realinode->i_mtime) ||
>                      !timespec_equal(&inode->i_ctime, &realinode->i_ctime))) {
>                         inode->i_mtime = realinode->i_mtime;
>                         inode->i_ctime = realinode->i_ctime;
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index c3d8c7ea180f..006dc70d7425 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -107,9 +107,6 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
>         if (inode && d_inode(dentry) == inode)
>                 return dentry;
>
> -       if (flags & D_REAL_UPPER)
> -               return ovl_dentry_upper(dentry);
> -
>         if (!d_is_reg(dentry)) {
>                 if (!inode || inode == d_inode(dentry))
>                         return dentry;
> diff --git a/include/linux/dcache.h b/include/linux/dcache.h
> index 82a99d366aec..4c7ab11c627a 100644
> --- a/include/linux/dcache.h
> +++ b/include/linux/dcache.h
> @@ -565,9 +565,6 @@ static inline struct dentry *d_backing_dentry(struct dentry *upper)
>         return upper;
>  }
>
> -/* d_real() flags */
> -#define D_REAL_UPPER   0x2     /* return upper dentry or NULL if non-upper */
> -

Premature removal of constant. Still in use by may_write_real() at this point.

Thanks,
Amir.