nilfs2: change sc_timer from a pointer to an embedded one in struct nilfs_sc_info

In nilfs_segctor_thread(), timer is a local variable allocated on stack. Its
address can't be set to sci->sc_timer and passed in several procedures.

It works now by chance, just because other procedures are called by
nilfs_segctor_thread() directly or indirectly and the stack hasn't been
deallocated yet.

Signed-off-by: Li Hong <lihong.hi@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

2 files changed, 14 insertions, 19 deletions

diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 89a15f4bfeb9..8b4e280b96b4 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2159,9 +2159,9 @@ static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
 {
         spin_lock(&sci->sc_state_lock);
-        if (sci->sc_timer && !(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
-                sci->sc_timer->expires = jiffies + sci->sc_interval;
-                add_timer(sci->sc_timer);
+        if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
+                sci->sc_timer.expires = jiffies + sci->sc_interval;
+                add_timer(&sci->sc_timer);
                 sci->sc_state |= NILFS_SEGCTOR_COMMIT;
         }
         spin_unlock(&sci->sc_state_lock);
@@ -2366,9 +2366,7 @@ static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
         spin_lock(&sci->sc_state_lock);
         sci->sc_seq_accepted = sci->sc_seq_request;
         spin_unlock(&sci->sc_state_lock);
-
-        if (sci->sc_timer)
-                del_timer_sync(sci->sc_timer);
+        del_timer_sync(&sci->sc_timer);
 }
 
 /**
@@ -2394,9 +2392,9 @@ static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
                         sci->sc_flush_request &= ~FLUSH_DAT_BIT;
 
                 /* re-enable timer if checkpoint creation was not done */
-                if (sci->sc_timer && (sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
-                    time_before(jiffies, sci->sc_timer->expires))
-                        add_timer(sci->sc_timer);
+                if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
+                    time_before(jiffies, sci->sc_timer.expires))
+                        add_timer(&sci->sc_timer);
         }
         spin_unlock(&sci->sc_state_lock);
 }
@@ -2575,13 +2573,10 @@ static int nilfs_segctor_thread(void *arg)
 {
         struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
         struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
-        struct timer_list timer;
         int timeout = 0;
 
-        init_timer(&timer);
-        timer.data = (unsigned long)current;
-        timer.function = nilfs_construction_timeout;
-        sci->sc_timer = &timer;
+        sci->sc_timer.data = (unsigned long)current;
+        sci->sc_timer.function = nilfs_construction_timeout;
 
         /* start sync. */
         sci->sc_task = current;
@@ -2630,7 +2625,7 @@ static int nilfs_segctor_thread(void *arg)
                         should_sleep = 0;
                 else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
                         should_sleep = time_before(jiffies,
-                                                   sci->sc_timer->expires);
+                                        sci->sc_timer.expires);
 
                 if (should_sleep) {
                         spin_unlock(&sci->sc_state_lock);
@@ -2639,7 +2634,7 @@ static int nilfs_segctor_thread(void *arg)
                 }
                 finish_wait(&sci->sc_wait_daemon, &wait);
                 timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
-                           time_after_eq(jiffies, sci->sc_timer->expires));
+                           time_after_eq(jiffies, sci->sc_timer.expires));
 
                 if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
                         set_nilfs_discontinued(nilfs);
@@ -2648,8 +2643,6 @@ static int nilfs_segctor_thread(void *arg)
 
  end_thread:
         spin_unlock(&sci->sc_state_lock);
-        del_timer_sync(sci->sc_timer);
-        sci->sc_timer = NULL;
 
         /* end sync. */
         sci->sc_task = NULL;
@@ -2708,6 +2701,7 @@ static struct nilfs_sc_info *nilfs_segctor_new(struct nilfs_sb_info *sbi)
         INIT_LIST_HEAD(&sci->sc_write_logs);
         INIT_LIST_HEAD(&sci->sc_gc_inodes);
         INIT_LIST_HEAD(&sci->sc_copied_buffers);
+        init_timer(&sci->sc_timer);
 
         sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
         sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
@@ -2774,6 +2768,7 @@ static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
 
         down_write(&sbi->s_nilfs->ns_segctor_sem);
 
+        del_timer_sync(&sci->sc_timer);
         kfree(sci);
 }
 
diff --git a/fs/nilfs2/segment.h b/fs/nilfs2/segment.h
index 7aca76532683..dca142361ccf 100644
--- a/fs/nilfs2/segment.h
+++ b/fs/nilfs2/segment.h
@@ -177,7 +177,7 @@ struct nilfs_sc_info {
         unsigned long           sc_lseg_stime;  /* in 1/HZ seconds */
         unsigned long           sc_watermark;
 
-        struct timer_list      *sc_timer;
+        struct timer_list       sc_timer;
         struct task_struct     *sc_task;
 };