linux-kernel - [PATCH v1 03/10] Workqueue: fs: replace use of system_wq with system_percpu

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Message-ID: <20250625104934.184753-4-marco.crivellari@suse.com>
Date: Wed, 25 Jun 2025 12:49:27 +0200
From: Marco Crivellari <marco.crivellari@...e.com>
To: linux-kernel@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frederic Weisbecker <frederic@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Marco Crivellari <marco.crivellari@...e.com>,
	Michal Hocko <mhocko@...e.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>
Subject: [PATCH v1 03/10] Workqueue: fs: replace use of system_wq with system_percpu_wq

Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistentcy cannot be addressed without refactoring the API.

system_wq is a per-CPU worqueue, yet nothing in its name tells about that
CPU affinity constraint, which is very often not required by users.
Make it clear by adding a system_percpu_wq to all the fs subsystem.

The old wq will be kept for a few release cylces.

Suggested-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>
CC: Alexander Viro <viro@...iv.linux.org.uk>
CC: Christian Brauner <brauner@...nel.org>
---
 fs/aio.c            | 2 +-
 fs/fs-writeback.c   | 2 +-
 fs/fuse/dev.c       | 2 +-
 fs/fuse/inode.c     | 2 +-
 fs/nfs/namespace.c  | 2 +-
 fs/nfs/nfs4renewd.c | 2 +-
 6 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 7b976b564cfc..747e9b5bba23 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -636,7 +636,7 @@ static void free_ioctx_reqs(struct percpu_ref *ref)
 
 	/* Synchronize against RCU protected table->table[] dereferences */
 	INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
-	queue_rcu_work(system_wq, &ctx->free_rwork);
+	queue_rcu_work(system_percpu_wq, &ctx->free_rwork);
 }
 
 /*
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index cc57367fb641..cf51a265bf27 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2442,7 +2442,7 @@ static int dirtytime_interval_handler(const struct ctl_table *table, int write,
 
 	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 	if (ret == 0 && write)
-		mod_delayed_work(system_wq, &dirtytime_work, 0);
+		mod_delayed_work(system_percpu_wq, &dirtytime_work, 0);
 	return ret;
 }
 
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 6dcbaa218b7a..64b623471a09 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -118,7 +118,7 @@ void fuse_check_timeout(struct work_struct *work)
 	    goto abort_conn;
 
 out:
-	queue_delayed_work(system_wq, &fc->timeout.work,
+	queue_delayed_work(system_percpu_wq, &fc->timeout.work,
 			   fuse_timeout_timer_freq);
 	return;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index fd48e8d37f2e..6a608ea77d09 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1268,7 +1268,7 @@ static void set_request_timeout(struct fuse_conn *fc, unsigned int timeout)
 {
 	fc->timeout.req_timeout = secs_to_jiffies(timeout);
 	INIT_DELAYED_WORK(&fc->timeout.work, fuse_check_timeout);
-	queue_delayed_work(system_wq, &fc->timeout.work,
+	queue_delayed_work(system_percpu_wq, &fc->timeout.work,
 			   fuse_timeout_timer_freq);
 }
 
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index 973aed9cc5fe..0689369c8a63 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -336,7 +336,7 @@ static int param_set_nfs_timeout(const char *val, const struct kernel_param *kp)
 			num *= HZ;
 		*((int *)kp->arg) = num;
 		if (!list_empty(&nfs_automount_list))
-			mod_delayed_work(system_wq, &nfs_automount_task, num);
+			mod_delayed_work(system_percpu_wq, &nfs_automount_task, num);
 	} else {
 		*((int *)kp->arg) = -1*HZ;
 		cancel_delayed_work(&nfs_automount_task);
diff --git a/fs/nfs/nfs4renewd.c b/fs/nfs/nfs4renewd.c
index db3811af0796..18ae614e5a6c 100644
--- a/fs/nfs/nfs4renewd.c
+++ b/fs/nfs/nfs4renewd.c
@@ -122,7 +122,7 @@ nfs4_schedule_state_renewal(struct nfs_client *clp)
 		timeout = 5 * HZ;
 	dprintk("%s: requeueing work. Lease period = %ld\n",
 			__func__, (timeout + HZ - 1) / HZ);
-	mod_delayed_work(system_wq, &clp->cl_renewd, timeout);
+	mod_delayed_work(system_percpu_wq, &clp->cl_renewd, timeout);
 	set_bit(NFS_CS_RENEWD, &clp->cl_res_state);
 	spin_unlock(&clp->cl_lock);
 }
-- 
2.49.0