From 29264d92a0f157f3147129066d912718b99fc6b0 Mon Sep 17 00:00:00 2001
From: Roman Gushchin <guro@fb.com>
Date: Mon, 28 Jun 2021 19:35:50 -0700
Subject: [PATCH] writeback, cgroup: switch to rcu_work API in
inode_switch_wbs()
Inode's wb switching requires two steps divided by an RCU grace period.
It's currently implemented as an RCU callback inode_switch_wbs_rcu_fn(),
which schedules inode_switch_wbs_work_fn() as a work.
Switching to the rcu_work API allows to do the same in a cleaner and
slightly shorter form.
Link: https://lkml.kernel.org/r/20210608230225.2078447-5-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Dennis Zhou <dennis@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/fs-writeback.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e2cc860a001b9..96974e13a2035 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -335,8 +335,7 @@ struct inode_switch_wbs_context {
struct inode *inode;
struct bdi_writeback *new_wb;
- struct rcu_head rcu_head;
- struct work_struct work;
+ struct rcu_work work;
};
static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi)
@@ -352,7 +351,7 @@ static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi)
static void inode_switch_wbs_work_fn(struct work_struct *work)
{
struct inode_switch_wbs_context *isw =
- container_of(work, struct inode_switch_wbs_context, work);
+ container_of(to_rcu_work(work), struct inode_switch_wbs_context, work);
struct inode *inode = isw->inode;
struct backing_dev_info *bdi = inode_to_bdi(inode);
struct address_space *mapping = inode->i_mapping;
@@ -469,16 +468,6 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
atomic_dec(&isw_nr_in_flight);
}
-static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head)
-{
- struct inode_switch_wbs_context *isw = container_of(rcu_head,
- struct inode_switch_wbs_context, rcu_head);
-
- /* needs to grab bh-unsafe locks, bounce to work item */
- INIT_WORK(&isw->work, inode_switch_wbs_work_fn);
- queue_work(isw_wq, &isw->work);
-}
-
/**
* inode_switch_wbs - change the wb association of an inode
* @inode: target inode
@@ -536,7 +525,8 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id)
* lock so that stat transfer can synchronize against them.
* Let's continue after I_WB_SWITCH is guaranteed to be visible.
*/
- call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn);
+ INIT_RCU_WORK(&isw->work, inode_switch_wbs_work_fn);
+ queue_rcu_work(isw_wq, &isw->work);
return;
out_free: