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Message-Id: <20240826174116.5008-8-konishi.ryusuke@gmail.com>
Date: Tue, 27 Aug 2024 02:41:15 +0900
From: Ryusuke Konishi <konishi.ryusuke@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-nilfs@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 7/8] nilfs2: use kthread_create and kthread_stop for the log writer thread
By using kthread_create() and kthread_stop() to start and stop the log
writer thread, eliminate custom thread start and stop helpers, as well
as the wait queue "sc_wait_task" on the "nilfs_sc_info" struct and
NILFS_SEGCTOR_QUIT flag that exist only to implement them.
Also, update the kernel doc comments of the changed functions as
appropriate.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@...il.com>
---
fs/nilfs2/segment.c | 82 +++++++++++++++++----------------------------
fs/nilfs2/segment.h | 3 --
2 files changed, 31 insertions(+), 54 deletions(-)
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 225f61ef66e7..013262ab5169 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2630,11 +2630,15 @@ static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
}
/**
- * nilfs_segctor_thread - main loop of the segment constructor thread.
+ * nilfs_segctor_thread - main loop of the log writer thread
* @arg: pointer to a struct nilfs_sc_info.
*
- * nilfs_segctor_thread() initializes a timer and serves as a daemon
- * to execute segment constructions.
+ * nilfs_segctor_thread() is the main loop function of the log writer kernel
+ * thread, which determines whether log writing is necessary, and if so,
+ * performs the log write in the background, or waits if not. It is also
+ * used to decide the background writeback of the superblock.
+ *
+ * Return: Always 0.
*/
static int nilfs_segctor_thread(void *arg)
{
@@ -2642,11 +2646,6 @@ static int nilfs_segctor_thread(void *arg)
struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
int timeout = 0;
- timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
-
- /* start sync. */
- sci->sc_task = current;
- wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
nilfs_info(sci->sc_super,
"segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
@@ -2657,7 +2656,7 @@ static int nilfs_segctor_thread(void *arg)
for (;;) {
int mode;
- if (sci->sc_state & NILFS_SEGCTOR_QUIT)
+ if (kthread_should_stop())
goto end_thread;
if (timeout || sci->sc_seq_request != sci->sc_seq_done)
@@ -2711,41 +2710,10 @@ static int nilfs_segctor_thread(void *arg)
/* end sync. */
sci->sc_task = NULL;
timer_shutdown_sync(&sci->sc_timer);
- wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
spin_unlock(&sci->sc_state_lock);
return 0;
}
-static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
-{
- struct task_struct *t;
-
- t = kthread_run(nilfs_segctor_thread, sci, "segctord");
- if (IS_ERR(t)) {
- int err = PTR_ERR(t);
-
- nilfs_err(sci->sc_super, "error %d creating segctord thread",
- err);
- return err;
- }
- wait_event(sci->sc_wait_task, sci->sc_task != NULL);
- return 0;
-}
-
-static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
- __acquires(&sci->sc_state_lock)
- __releases(&sci->sc_state_lock)
-{
- sci->sc_state |= NILFS_SEGCTOR_QUIT;
-
- while (sci->sc_task) {
- wake_up(&sci->sc_wait_daemon);
- spin_unlock(&sci->sc_state_lock);
- wait_event(sci->sc_wait_task, sci->sc_task == NULL);
- spin_lock(&sci->sc_state_lock);
- }
-}
-
/*
* Setup & clean-up functions
*/
@@ -2766,7 +2734,6 @@ static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
init_waitqueue_head(&sci->sc_wait_request);
init_waitqueue_head(&sci->sc_wait_daemon);
- init_waitqueue_head(&sci->sc_wait_task);
spin_lock_init(&sci->sc_state_lock);
INIT_LIST_HEAD(&sci->sc_dirty_files);
INIT_LIST_HEAD(&sci->sc_segbufs);
@@ -2821,8 +2788,12 @@ static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
up_write(&nilfs->ns_segctor_sem);
+ if (sci->sc_task) {
+ wake_up(&sci->sc_wait_daemon);
+ kthread_stop(sci->sc_task);
+ }
+
spin_lock(&sci->sc_state_lock);
- nilfs_segctor_kill_thread(sci);
flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
|| sci->sc_seq_request != sci->sc_seq_done);
spin_unlock(&sci->sc_state_lock);
@@ -2870,14 +2841,15 @@ static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
* This allocates a log writer object, initializes it, and starts the
* log writer.
*
- * Return Value: On success, 0 is returned. On error, one of the following
- * negative error code is returned.
- *
- * %-ENOMEM - Insufficient memory available.
+ * Return: 0 on success, or the following negative error code on failure.
+ * * %-EINTR - Log writer thread creation failed due to interruption.
+ * * %-ENOMEM - Insufficient memory available.
*/
int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
{
struct the_nilfs *nilfs = sb->s_fs_info;
+ struct nilfs_sc_info *sci;
+ struct task_struct *t;
int err;
if (nilfs->ns_writer) {
@@ -2890,15 +2862,23 @@ int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
return 0;
}
- nilfs->ns_writer = nilfs_segctor_new(sb, root);
- if (!nilfs->ns_writer)
+ sci = nilfs_segctor_new(sb, root);
+ if (unlikely(!sci))
return -ENOMEM;
- err = nilfs_segctor_start_thread(nilfs->ns_writer);
- if (unlikely(err))
+ nilfs->ns_writer = sci;
+ t = kthread_create(nilfs_segctor_thread, sci, "segctord");
+ if (IS_ERR(t)) {
+ err = PTR_ERR(t);
+ nilfs_err(sb, "error %d creating segctord thread", err);
nilfs_detach_log_writer(sb);
+ return err;
+ }
+ sci->sc_task = t;
+ timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
- return err;
+ wake_up_process(sci->sc_task);
+ return 0;
}
/**
diff --git a/fs/nilfs2/segment.h b/fs/nilfs2/segment.h
index 7d1160a266df..f723f47ddc4e 100644
--- a/fs/nilfs2/segment.h
+++ b/fs/nilfs2/segment.h
@@ -105,7 +105,6 @@ struct nilfs_segsum_pointer {
* @sc_flush_request: inode bitmap of metadata files to be flushed
* @sc_wait_request: Client request queue
* @sc_wait_daemon: Daemon wait queue
- * @sc_wait_task: Start/end wait queue to control segctord task
* @sc_seq_request: Request counter
* @sc_seq_accepted: Accepted request count
* @sc_seq_done: Completion counter
@@ -158,7 +157,6 @@ struct nilfs_sc_info {
wait_queue_head_t sc_wait_request;
wait_queue_head_t sc_wait_daemon;
- wait_queue_head_t sc_wait_task;
__u32 sc_seq_request;
__u32 sc_seq_accepted;
@@ -191,7 +189,6 @@ enum {
};
/* sc_state */
-#define NILFS_SEGCTOR_QUIT 0x0001 /* segctord is being destroyed */
#define NILFS_SEGCTOR_COMMIT 0x0004 /* committed transaction exists */
/*
--
2.34.1
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