linux-kernel - Re: [PATCH 14/14] xfs: enable non-blocking timestamp updates

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Message-ID: <20251114153036.GA30882@lst.de>
Date: Fri, 14 Nov 2025 16:30:36 +0100
From: Christoph Hellwig <hch@....de>
To: Christian Brauner <brauner@...nel.org>
Cc: Al Viro <viro@...iv.linux.org.uk>, David Sterba <dsterba@...e.com>,
	Jan Kara <jack@...e.cz>, Mike Marshall <hubcap@...ibond.com>,
	Martin Brandenburg <martin@...ibond.com>,
	Carlos Maiolino <cem@...nel.org>, Stefan Roesch <shr@...com>,
	Jeff Layton <jlayton@...nel.org>, linux-kernel@...r.kernel.org,
	linux-btrfs@...r.kernel.org, gfs2@...ts.linux.dev,
	io-uring@...r.kernel.org, devel@...ts.orangefs.org,
	linux-unionfs@...r.kernel.org, linux-mtd@...ts.infradead.org,
	linux-xfs@...r.kernel.org, linux-nfs@...r.kernel.org
Subject: Re: [PATCH 14/14] xfs: enable non-blocking timestamp updates

On Fri, Nov 14, 2025 at 07:26:17AM +0100, Christoph Hellwig wrote:
> The lazytime path using generic_update_time can never block in XFS
> because there is no ->dirty_inode method that could block.  Allow
> non-blocking timestamp updates for this case.

As the report noted, it turns out my rebase lost the most important
thing here, which is to not reject S_NOWAIT for the lazytime path.
The incremental patch is below.  I'll resend on Monday, and officially
declare that Friday the 14th is the new Friday the 13th.

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 3d7b89ffacde..35dbabf1e111 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1196,9 +1196,13 @@ xfs_vn_update_time(
 	trace_xfs_update_time(ip);
 
 	if (inode->i_sb->s_flags & SB_LAZYTIME) {
-		if (!((flags & S_VERSION) &&
-		      inode_maybe_inc_iversion(inode, false)))
-			return generic_update_time(inode, flags);
+		int updated = inode_update_timestamps(inode, flags);
+
+		if (!(updated & S_VERSION)) {
+			if (updated)
+				mark_inode_dirty_time(inode, updated);
+			return 0;
+		}
 
 		/* Capture the iversion update that just occurred */
 		log_flags |= XFS_ILOG_CORE;