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Date:   Wed, 2 Aug 2023 10:48:53 -0700
From:   "Darrick J. Wong" <djwong@kernel.org>
To:     Jeff Layton <jlayton@kernel.org>
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Subject: Re: [PATCH v6 5/7] xfs: switch to multigrain timestamps
Message-ID: <20230802174853.GC11352@frogsfrogsfrogs>
References: <20230725-mgctime-v6-0-a794c2b7abca@kernel.org>
 <20230725-mgctime-v6-5-a794c2b7abca@kernel.org>
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In-Reply-To: <20230725-mgctime-v6-5-a794c2b7abca@kernel.org>
Precedence: bulk

On Tue, Jul 25, 2023 at 10:58:18AM -0400, Jeff Layton wrote:
> Enable multigrain timestamps, which should ensure that there is an
> apparent change to the timestamp whenever it has been written after
> being actively observed via getattr.
> 
> Also, anytime the mtime changes, the ctime must also change, and those
> are now the only two options for xfs_trans_ichgtime. Have that function
> unconditionally bump the ctime, and ASSERT that XFS_ICHGTIME_CHG is
> always set.
> 
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/xfs/libxfs/xfs_trans_inode.c | 6 +++---
>  fs/xfs/xfs_iops.c               | 4 ++--
>  fs/xfs/xfs_super.c              | 2 +-
>  3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_trans_inode.c b/fs/xfs/libxfs/xfs_trans_inode.c
> index 6b2296ff248a..ad22656376d3 100644
> --- a/fs/xfs/libxfs/xfs_trans_inode.c
> +++ b/fs/xfs/libxfs/xfs_trans_inode.c
> @@ -62,12 +62,12 @@ xfs_trans_ichgtime(
>  	ASSERT(tp);
>  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
>  
> -	tv = current_time(inode);
> +	/* If the mtime changes, then ctime must also change */
> +	ASSERT(flags & XFS_ICHGTIME_CHG);
>  
> +	tv = inode_set_ctime_current(inode);
>  	if (flags & XFS_ICHGTIME_MOD)
>  		inode->i_mtime = tv;
> -	if (flags & XFS_ICHGTIME_CHG)
> -		inode_set_ctime_to_ts(inode, tv);
>  	if (flags & XFS_ICHGTIME_CREATE)
>  		ip->i_crtime = tv;
>  }
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 3a9363953ef2..3f89ef5a2820 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -573,10 +573,10 @@ xfs_vn_getattr(
>  	stat->gid = vfsgid_into_kgid(vfsgid);
>  	stat->ino = ip->i_ino;
>  	stat->atime = inode->i_atime;
> -	stat->mtime = inode->i_mtime;
> -	stat->ctime = inode_get_ctime(inode);
>  	stat->blocks = XFS_FSB_TO_BB(mp, ip->i_nblocks + ip->i_delayed_blks);
>  
> +	fill_mg_cmtime(request_mask, inode, stat);

Huh.  I would've thought @stat would come first since that's what we're
acting upon, but ... eh. :)

If everyone else is ok with the fill_mg_cmtime signature,
Acked-by: Darrick J. Wong <djwong@kernel.org>

--D

> +
>  	if (xfs_has_v3inodes(mp)) {
>  		if (request_mask & STATX_BTIME) {
>  			stat->result_mask |= STATX_BTIME;
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 818510243130..4b10edb2c972 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -2009,7 +2009,7 @@ static struct file_system_type xfs_fs_type = {
>  	.init_fs_context	= xfs_init_fs_context,
>  	.parameters		= xfs_fs_parameters,
>  	.kill_sb		= kill_block_super,
> -	.fs_flags		= FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
> +	.fs_flags		= FS_REQUIRES_DEV | FS_ALLOW_IDMAP | FS_MGTIME,
>  };
>  MODULE_ALIAS_FS("xfs");
>  
> 
> -- 
> 2.41.0
>