[PATCH v4 17/19] xfs: avoid setting XFS_ILOG_CORE if i_version doesn't need incrementing

[Darrick J. Wong]

On Fri, Dec 22, 2017 at 07:05:54AM -0500, Jeff Layton wrote:
> From: Jeff Layton <jlayton at redhat.com>
> 
> If XFS_ILOG_CORE is already set then go ahead and increment it.
> 
> Signed-off-by: Jeff Layton <jlayton at redhat.com>

Looks ok,
Acked-by: Darrick J. Wong <darrick.wong at oracle.com>

> ---
>  fs/xfs/xfs_trans_inode.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/xfs_trans_inode.c b/fs/xfs/xfs_trans_inode.c
> index 225544327c4f..4a89da4b6fe7 100644
> --- a/fs/xfs/xfs_trans_inode.c
> +++ b/fs/xfs/xfs_trans_inode.c
> @@ -112,15 +112,17 @@ xfs_trans_log_inode(
>  
>  	/*
>  	 * First time we log the inode in a transaction, bump the inode change
> -	 * counter if it is configured for this to occur. We don't use
> -	 * inode_inc_version() because there is no need for extra locking around
> -	 * i_version as we already hold the inode locked exclusively for
> -	 * metadata modification.
> +	 * counter if it is configured for this to occur. While we have the
> +	 * inode locked exclusively for metadata modification, we can usually
> +	 * avoid setting XFS_ILOG_CORE if no one has queried the value since
> +	 * the last time it was incremented. If we have XFS_ILOG_CORE already
> +	 * set however, then go ahead and bump the i_version counter
> +	 * unconditionally.
>  	 */
>  	if (!(ip->i_itemp->ili_item.li_desc->lid_flags & XFS_LID_DIRTY) &&
>  	    IS_I_VERSION(VFS_I(ip))) {
> -		inode_inc_iversion(VFS_I(ip));
> -		flags |= XFS_ILOG_CORE;
> +		if (inode_maybe_inc_iversion(VFS_I(ip), flags & XFS_ILOG_CORE))
> +			flags |= XFS_ILOG_CORE;
>  	}
>  
>  	tp->t_flags |= XFS_TRANS_DIRTY;
> -- 
> 2.14.3
> 
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