Re: [PATCH 01/13] xfs: xfs_iflock is no longer a completion

From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 01/13] xfs: xfs_iflock is no longer a completion
Date: Sat, 22 Aug 2020 08:41:16 +0100	[thread overview]
Message-ID: <20200822074116.GA8859@infradead.org> (raw)
In-Reply-To: <20200812092556.2567285-2-david@fromorbit.com>

On Wed, Aug 12, 2020 at 07:25:44PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> With the recent rework of the inode cluster flushing, we no longer
> ever wait on the the inode flush "lock". It was never a lock in the
> first place, just a completion to allow callers to wait for inode IO
> to complete. We now never wait for flush completion as all inode
> flushing is non-blocking. Hence we can get rid of all the iflock
> infrastructure and instead just set and check a state flag.
> 
> Rename the XFS_IFLOCK flag to XFS_IFLUSHING, convert all the
> xfs_iflock_nowait() test-and-set operations on that flag, and
> replace all the xfs_ifunlock() calls to clear operations.
> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  fs/xfs/xfs_icache.c     | 17 ++++------
>  fs/xfs/xfs_inode.c      | 73 +++++++++++++++--------------------------
>  fs/xfs/xfs_inode.h      | 33 +------------------
>  fs/xfs/xfs_inode_item.c | 15 ++++-----
>  fs/xfs/xfs_inode_item.h |  4 +--
>  fs/xfs/xfs_mount.c      | 11 ++++---
>  fs/xfs/xfs_super.c      | 10 +++---
>  7 files changed, 55 insertions(+), 108 deletions(-)
> 
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 101028ebb571..aa6aad258670 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -52,7 +52,6 @@ xfs_inode_alloc(
>  
>  	XFS_STATS_INC(mp, vn_active);
>  	ASSERT(atomic_read(&ip->i_pincount) == 0);
> -	ASSERT(!xfs_isiflocked(ip));
>  	ASSERT(ip->i_ino == 0);
>  
>  	/* initialise the xfs inode */
> @@ -123,7 +122,7 @@ void
>  xfs_inode_free(
>  	struct xfs_inode	*ip)
>  {
> -	ASSERT(!xfs_isiflocked(ip));
> +	ASSERT(!xfs_iflags_test(ip, XFS_IFLUSHING));
>  
>  	/*
>  	 * Because we use RCU freeing we need to ensure the inode always
> @@ -1035,23 +1034,21 @@ xfs_reclaim_inode(
>  
>  	if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
>  		goto out;
> -	if (!xfs_iflock_nowait(ip))
> +	if (xfs_iflags_test_and_set(ip, XFS_IFLUSHING))
>  		goto out_iunlock;
>  
>  	if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
>  		xfs_iunpin_wait(ip);
> -		/* xfs_iflush_abort() drops the flush lock */

Maybe keeps this as

		/*  xfs_iflush_abort() clears XFS_IFLUSHING */

> @@ -3661,7 +3643,6 @@ xfs_iflush_cluster(
>  		 */
>  		if (XFS_FORCED_SHUTDOWN(mp)) {
>  			xfs_iunpin_wait(ip);
> -			/* xfs_iflush_abort() drops the flush lock */

Same here.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>