linux-kernel - [PATCH 06/10] fs: factor out a sync

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Message-ID: <20251217061015.923954-7-hch@lst.de>
Date: Wed, 17 Dec 2025 07:09:39 +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,
	linux-fsdevel@...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: [PATCH 06/10] fs: factor out a sync_lazytime helper

Centralize how we synchronize a lazytime update into the actual on-disk
timestamp into a single helper.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Jeff Layton <jlayton@...nel.org>
---
 fs/fs-writeback.c                | 22 +++++++++++++++-------
 fs/inode.c                       |  5 +----
 fs/internal.h                    |  3 ++-
 fs/sync.c                        |  4 ++--
 include/trace/events/writeback.h |  6 ------
 5 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7870c158e4a2..fa555e10d8b9 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1711,6 +1711,16 @@ static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
 	}
 }
 
+bool sync_lazytime(struct inode *inode)
+{
+	if (!(inode_state_read_once(inode) & I_DIRTY_TIME))
+		return false;
+
+	trace_writeback_lazytime(inode);
+	mark_inode_dirty_sync(inode);
+	return true;
+}
+
 /*
  * Write out an inode and its dirty pages (or some of its dirty pages, depending
  * on @wbc->nr_to_write), and clear the relevant dirty flags from i_state.
@@ -1750,17 +1760,15 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 	}
 
 	/*
-	 * If the inode has dirty timestamps and we need to write them, call
-	 * mark_inode_dirty_sync() to notify the filesystem about it and to
-	 * change I_DIRTY_TIME into I_DIRTY_SYNC.
+	 * For data integrity writeback, or when the dirty interval expired,
+	 * ask the file system to propagata lazy timestamp updates into real
+	 * dirty state.
 	 */
 	if ((inode_state_read_once(inode) & I_DIRTY_TIME) &&
 	    (wbc->sync_mode == WB_SYNC_ALL ||
 	     time_after(jiffies, inode->dirtied_time_when +
-			dirtytime_expire_interval * HZ))) {
-		trace_writeback_lazytime(inode);
-		mark_inode_dirty_sync(inode);
-	}
+			dirtytime_expire_interval * HZ)))
+		sync_lazytime(inode);
 
 	/*
 	 * Get and clear the dirty flags from i_state.  This needs to be done
diff --git a/fs/inode.c b/fs/inode.c
index 2c0d69f7fd01..f1c09fc0913d 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1979,11 +1979,8 @@ void iput(struct inode *inode)
 	if (atomic_add_unless(&inode->i_count, -1, 1))
 		return;
 
-	if ((inode_state_read_once(inode) & I_DIRTY_TIME) && inode->i_nlink) {
-		trace_writeback_lazytime_iput(inode);
-		mark_inode_dirty_sync(inode);
+	if (inode->i_nlink && sync_lazytime(inode))
 		goto retry;
-	}
 
 	spin_lock(&inode->i_lock);
 	if (unlikely((inode_state_read(inode) & I_DIRTY_TIME) && inode->i_nlink)) {
diff --git a/fs/internal.h b/fs/internal.h
index ab638d41ab81..18a062c1b5b0 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -214,7 +214,8 @@ bool in_group_or_capable(struct mnt_idmap *idmap,
 /*
  * fs-writeback.c
  */
-extern long get_nr_dirty_inodes(void);
+long get_nr_dirty_inodes(void);
+bool sync_lazytime(struct inode *inode);
 
 /*
  * dcache.c
diff --git a/fs/sync.c b/fs/sync.c
index 431fc5f5be06..4283af7119d1 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -183,8 +183,8 @@ int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
 
 	if (!file->f_op->fsync)
 		return -EINVAL;
-	if (!datasync && (inode_state_read_once(inode) & I_DIRTY_TIME))
-		mark_inode_dirty_sync(inode);
+	if (!datasync)
+		sync_lazytime(inode);
 	return file->f_op->fsync(file, start, end, datasync);
 }
 EXPORT_SYMBOL(vfs_fsync_range);
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 311a341e6fe4..7162d03e69a5 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -856,12 +856,6 @@ DEFINE_EVENT(writeback_inode_template, writeback_lazytime,
 	TP_ARGS(inode)
 );
 
-DEFINE_EVENT(writeback_inode_template, writeback_lazytime_iput,
-	TP_PROTO(struct inode *inode),
-
-	TP_ARGS(inode)
-);
-
 DEFINE_EVENT(writeback_inode_template, writeback_dirty_inode_enqueue,
 
 	TP_PROTO(struct inode *inode),
-- 
2.47.3