Re: [PATCH v3 4/5] xfs: check tp->t_dqinfo value instead of the XFS_TRANS_DQ_DIRTY flag

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Oct 07, 2020 at 10:51:11PM +0800, xiakaixu1987@gmail.com wrote:
> From: Kaixu Xia <kaixuxia@tencent.com>
> 
> Nowadays the only things that the XFS_TRANS_DQ_DIRTY flag seems to do
> are indicates the tp->t_dqinfo->dqs[XFS_QM_TRANS_{USR,GRP,PRJ}] values
> changed and check in xfs_trans_apply_dquot_deltas() and the unreserve
> variant xfs_trans_unreserve_and_mod_dquots(). Actually, we also can
> use the tp->t_dqinfo value instead of the XFS_TRANS_DQ_DIRTY flag, that
> is to say, we allocate the new tp->t_dqinfo only when the qtrx values
> changed, so the tp->t_dqinfo value isn't NULL equals the XFS_TRANS_DQ_DIRTY
> flag is set, we only need to check if tp->t_dqinfo == NULL in
> xfs_trans_apply_dquot_deltas() and its unreserve variant to determine
> whether lock all of the dquots and join them to the transaction.
> 
> Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
> ---
>  fs/xfs/libxfs/xfs_shared.h |  1 -
>  fs/xfs/xfs_inode.c         |  8 +-------
>  fs/xfs/xfs_trans_dquot.c   | 17 ++---------------
>  3 files changed, 3 insertions(+), 23 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_shared.h b/fs/xfs/libxfs/xfs_shared.h
> index c795ae47b3c9..8c61a461bf7b 100644
> --- a/fs/xfs/libxfs/xfs_shared.h
> +++ b/fs/xfs/libxfs/xfs_shared.h
> @@ -62,7 +62,6 @@ void	xfs_log_get_max_trans_res(struct xfs_mount *mp,
>  #define	XFS_TRANS_SB_DIRTY	0x02	/* superblock is modified */
>  #define	XFS_TRANS_PERM_LOG_RES	0x04	/* xact took a permanent log res */
>  #define	XFS_TRANS_SYNC		0x08	/* make commit synchronous */
> -#define XFS_TRANS_DQ_DIRTY	0x10	/* at least one dquot in trx dirty */
>  #define XFS_TRANS_RESERVE	0x20    /* OK to use reserved data blocks */
>  #define XFS_TRANS_NO_WRITECOUNT 0x40	/* do not elevate SB writecount */
>  #define XFS_TRANS_RES_FDBLKS	0x80	/* reserve newly freed blocks */
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 49624973eecc..9108eed0ea45 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -941,7 +941,6 @@ xfs_dir_ialloc(
>  	xfs_buf_t	*ialloc_context = NULL;
>  	int		code;
>  	void		*dqinfo;
> -	uint		tflags;
>  
>  	tp = *tpp;
>  	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
> @@ -1000,12 +999,9 @@ xfs_dir_ialloc(
>  		 * and attach it to the next transaction.
>  		 */
>  		dqinfo = NULL;
> -		tflags = 0;
>  		if (tp->t_dqinfo) {
>  			dqinfo = (void *)tp->t_dqinfo;
>  			tp->t_dqinfo = NULL;
> -			tflags = tp->t_flags & XFS_TRANS_DQ_DIRTY;
> -			tp->t_flags &= ~(XFS_TRANS_DQ_DIRTY);
>  		}
>  
>  		code = xfs_trans_roll(&tp);
> @@ -1013,10 +1009,8 @@ xfs_dir_ialloc(
>  		/*
>  		 * Re-attach the quota info that we detached from prev trx.
>  		 */
> -		if (dqinfo) {
> +		if (dqinfo)
>  			tp->t_dqinfo = dqinfo;
> -			tp->t_flags |= tflags;
> -		}
>  
>  		if (code) {
>  			xfs_buf_relse(ialloc_context);
> diff --git a/fs/xfs/xfs_trans_dquot.c b/fs/xfs/xfs_trans_dquot.c
> index 1b56065c9ff1..0ebfd7930382 100644
> --- a/fs/xfs/xfs_trans_dquot.c
> +++ b/fs/xfs/xfs_trans_dquot.c
> @@ -84,13 +84,6 @@ xfs_trans_dup_dqinfo(
>  
>  	xfs_trans_alloc_dqinfo(ntp);
>  
> -	/*
> -	 * Because the quota blk reservation is carried forward,
> -	 * it is also necessary to carry forward the DQ_DIRTY flag.
> -	 */
> -	if (otp->t_flags & XFS_TRANS_DQ_DIRTY)
> -		ntp->t_flags |= XFS_TRANS_DQ_DIRTY;
> -
>  	for (j = 0; j < XFS_QM_TRANS_DQTYPES; j++) {
>  		oqa = otp->t_dqinfo->dqs[j];
>  		nqa = ntp->t_dqinfo->dqs[j];
> @@ -270,8 +263,6 @@ xfs_trans_mod_dquot(
>  
>  	if (delta)
>  		trace_xfs_trans_mod_dquot_after(qtrx);
> -
> -	tp->t_flags |= XFS_TRANS_DQ_DIRTY;
>  }
>  
>  
> @@ -348,7 +339,7 @@ xfs_trans_apply_dquot_deltas(
>  	int64_t			totalbdelta;
>  	int64_t			totalrtbdelta;
>  
> -	if (!(tp->t_flags & XFS_TRANS_DQ_DIRTY))
> +	if (!tp->t_dqinfo)
>  		return;
>  
>  	ASSERT(tp->t_dqinfo);
> @@ -490,7 +481,7 @@ xfs_trans_unreserve_and_mod_dquots(
>  	struct xfs_dqtrx	*qtrx, *qa;
>  	bool			locked;
>  
> -	if (!tp->t_dqinfo || !(tp->t_flags & XFS_TRANS_DQ_DIRTY))
> +	if (!tp->t_dqinfo)
>  		return;
>  
>  	for (j = 0; j < XFS_QM_TRANS_DQTYPES; j++) {
> @@ -695,7 +686,6 @@ xfs_trans_dqresv(
>  	 * because we don't have the luxury of a transaction envelope then.
>  	 */
>  	if (tp) {
> -		ASSERT(tp->t_dqinfo);
>  		ASSERT(flags & XFS_QMOPT_RESBLK_MASK);
>  		if (nblks != 0)
>  			xfs_trans_mod_dquot(tp, dqp,
> @@ -749,9 +739,6 @@ xfs_trans_reserve_quota_bydquots(
>  	if (!XFS_IS_QUOTA_RUNNING(mp) || !XFS_IS_QUOTA_ON(mp))
>  		return 0;
>  
> -	if (tp && tp->t_dqinfo == NULL)
> -		xfs_trans_alloc_dqinfo(tp);
> -

This also should be a separate patch (or I guess the previous one?)
in which the commit log points out that the allocation is already
covered by the chain xfs_trans_reserve_quota_bydquots ->
xfs_trans_dqresv -> xfs_trans_mod_dquot.

--D

>  	ASSERT(flags & XFS_QMOPT_RESBLK_MASK);
>  
>  	if (udqp) {
> -- 
> 2.20.0
>