Re: [PATCH 9/7] xfs: remove SYNC_BDFLUSH

[Eric Sandeen <sandeen@sandeen.net>]

Christoph Hellwig wrote:
> SYNC_BDFLUSH is a leftover from IRIX and rather misnamed for todays
> code.  Make xfs_sync_fsdata and xfs_dq_sync use the SYNC_TRYLOCK flag
> for not blocking on logs just as the inode sync code already does.
> 
> For xfs_sync_fsdata it's a trivial 1:1 replacement, but for xfs_qm_sync
> I use the opportunity to decouple the non-blocking lock case from the
> different flushing modes, similar to the inode sync code.
> 
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Eric Sandeen <sandeen@sandeen.net>

> Index: xfs/fs/xfs/linux-2.6/xfs_sync.c
> ===================================================================
> --- xfs.orig/fs/xfs/linux-2.6/xfs_sync.c	2009-05-27 13:02:57.426938830 +0200
> +++ xfs/fs/xfs/linux-2.6/xfs_sync.c	2009-05-27 13:07:53.227939055 +0200
> @@ -350,7 +350,7 @@ xfs_sync_fsdata(
>  	 * If this is xfssyncd() then only sync the superblock if we can
>  	 * lock it without sleeping and it is not pinned.
>  	 */
> -	if (flags & SYNC_BDFLUSH) {
> +	if (flags & SYNC_TRYLOCK) {
>  		ASSERT(!(flags & SYNC_WAIT));
>  
>  		bp = xfs_getsb(mp, XFS_BUF_TRYLOCK);
> @@ -415,7 +415,7 @@ xfs_quiesce_data(
>  
>  	/* push non-blocking */
>  	xfs_sync_data(mp, 0);
> -	xfs_qm_sync(mp, SYNC_BDFLUSH);
> +	xfs_qm_sync(mp, SYNC_TRYLOCK);
>  	xfs_filestream_flush(mp);
>  
>  	/* push and block */
> @@ -565,8 +565,8 @@ xfs_sync_worker(
>  		xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
>  		xfs_reclaim_inodes(mp, XFS_IFLUSH_DELWRI_ELSE_ASYNC);
>  		/* dgc: errors ignored here */
> -		error = xfs_qm_sync(mp, SYNC_BDFLUSH);
> -		error = xfs_sync_fsdata(mp, SYNC_BDFLUSH);
> +		error = xfs_qm_sync(mp, SYNC_TRYLOCK);
> +		error = xfs_sync_fsdata(mp, SYNC_TRYLOCK);
>  		if (xfs_log_need_covered(mp))
>  			error = xfs_commit_dummy_trans(mp, XFS_LOG_FORCE);
>  	}
> Index: xfs/fs/xfs/quota/xfs_qm.c
> ===================================================================
> --- xfs.orig/fs/xfs/quota/xfs_qm.c	2009-05-27 13:04:00.607842293 +0200
> +++ xfs/fs/xfs/quota/xfs_qm.c	2009-05-27 13:10:21.688940102 +0200
> @@ -905,11 +905,6 @@ xfs_qm_dqdetach(
>  	}
>  }
>  
> -/*
> - * This is called to sync quotas. We can be told to use non-blocking
> - * semantics by either the SYNC_BDFLUSH flag or the absence of the
> - * SYNC_WAIT flag.
> - */
>  int
>  xfs_qm_sync(
>  	xfs_mount_t	*mp,
> @@ -918,17 +913,13 @@ xfs_qm_sync(
>  	int		recl, restarts;
>  	xfs_dquot_t	*dqp;
>  	uint		flush_flags;
> -	boolean_t	nowait;
>  	int		error;
>  
>  	if (!XFS_IS_QUOTA_RUNNING(mp) || !XFS_IS_QUOTA_ON(mp))
>  		return 0;
>  
> +	flush_flags = (flags & SYNC_WAIT) ? XFS_QMOPT_SYNC : XFS_QMOPT_DELWRI;
>  	restarts = 0;
> -	/*
> -	 * We won't block unless we are asked to.
> -	 */
> -	nowait = (boolean_t)(flags & SYNC_BDFLUSH || (flags & SYNC_WAIT) == 0);
>  
>    again:
>  	xfs_qm_mplist_lock(mp);
> @@ -948,18 +939,10 @@ xfs_qm_sync(
>  		 * don't 'seem' to be dirty. ie. don't acquire dqlock.
>  		 * This is very similar to what xfs_sync does with inodes.
>  		 */
> -		if (flags & SYNC_BDFLUSH) {
> -			if (! XFS_DQ_IS_DIRTY(dqp))
> +		if (flags & SYNC_TRYLOCK) {
> +			if (!XFS_DQ_IS_DIRTY(dqp))
>  				continue;
> -		}
> -
> -		if (nowait) {
> -			/*
> -			 * Try to acquire the dquot lock. We are NOT out of
> -			 * lock order, but we just don't want to wait for this
> -			 * lock, unless somebody wanted us to.
> -			 */
> -			if (! xfs_qm_dqlock_nowait(dqp))
> +			if (!xfs_qm_dqlock_nowait(dqp))
>  				continue;
>  		} else {
>  			xfs_dqlock(dqp);
> @@ -976,7 +959,7 @@ xfs_qm_sync(
>  		/* XXX a sentinel would be better */
>  		recl = XFS_QI_MPLRECLAIMS(mp);
>  		if (!xfs_dqflock_nowait(dqp)) {
> -			if (nowait) {
> +			if (flags & SYNC_TRYLOCK) {
>  				xfs_dqunlock(dqp);
>  				continue;
>  			}
> @@ -994,7 +977,6 @@ xfs_qm_sync(
>  		 * Let go of the mplist lock. We don't want to hold it
>  		 * across a disk write
>  		 */
> -		flush_flags = (nowait) ? XFS_QMOPT_DELWRI : XFS_QMOPT_SYNC;
>  		xfs_qm_mplist_unlock(mp);
>  		xfs_dqtrace_entry(dqp, "XQM_SYNC: DQFLUSH");
>  		error = xfs_qm_dqflush(dqp, flush_flags);
> Index: xfs/fs/xfs/linux-2.6/xfs_sync.h
> ===================================================================
> --- xfs.orig/fs/xfs/linux-2.6/xfs_sync.h	2009-05-27 13:07:58.997814418 +0200
> +++ xfs/fs/xfs/linux-2.6/xfs_sync.h	2009-05-27 13:08:19.922972203 +0200
> @@ -29,9 +29,8 @@ typedef struct xfs_sync_work {
>  	struct completion	*w_completion;
>  } xfs_sync_work_t;
>  
> -#define SYNC_WAIT		0x0004	/* wait for i/o to complete */
> -#define SYNC_BDFLUSH		0x0008	/* BDFLUSH is calling -- don't block */
> -#define SYNC_TRYLOCK		0x0020  /* only try to lock inodes */
> +#define SYNC_WAIT		0x0001	/* wait for i/o to complete */
> +#define SYNC_TRYLOCK		0x0002  /* only try to lock inodes */
>  
>  int xfs_syncd_init(struct xfs_mount *mp);
>  void xfs_syncd_stop(struct xfs_mount *mp);
> 
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