[PATCH 3/3] nilfs2: stop using periodic write_super callback

[Jiro SEKIBA <jir-hfpbi5WX9J54Eiagz67IpQ@public.gmane.org>]

This patch makes commiting super block in nilfs internal thread,
instead of periodic write_super callback.

VFS layer calls ->write_super callback periodically.  However,
it looks like that calling back is ommited when disk I/O is busy.
And when cleanerd (nilfs GC) is runnig, disk I/O tend to be busy thus
nilfs superblock is not synchronized as nilfs designed.

To avoid it, syncing superblock by nilfs thread instead of pdflush.

Signed-off-by: Jiro SEKIBA <jir-hfpbi5WX9J54Eiagz67IpQ@public.gmane.org>
---
 fs/nilfs2/segment.c |   12 +++++++++++-
 fs/nilfs2/super.c   |    2 +-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 8b5e477..46f7a49 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2486,8 +2486,10 @@ static int nilfs_segctor_construct(struct nilfs_sc_info *sci,
 			atomic_set(&nilfs->ns_ndirtyblks, 0);
 		if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
 		    nilfs_discontinued(nilfs)) {
+			u64 t = get_seconds();
 			down_write(&nilfs->ns_sem);
-			req->sb_err = nilfs_commit_super(sbi, 0);
+			req->sb_err = nilfs_commit_super(sbi,
+					nilfs_altsb_need_update(nilfs, t));
 			up_write(&nilfs->ns_sem);
 		}
 	}
@@ -2675,6 +2677,9 @@ static int nilfs_segctor_thread(void *arg)
 	} else {
 		DEFINE_WAIT(wait);
 		int should_sleep = 1;
+		u64 t;
+		struct nilfs_sb_info *sbi;
+		struct the_nilfs *nilfs;
 
 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
 				TASK_INTERRUPTIBLE);
@@ -2695,6 +2700,11 @@ 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));
+		t = get_seconds();
+		sbi = sci->sc_sbi;
+		nilfs = sbi->s_nilfs;
+		if (sci->sc_super->s_dirt && nilfs_sb_need_update(nilfs, t))
+			set_nilfs_discontinued(nilfs);
 	}
 	goto loop;
 
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index d85b360..a8c5875 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -534,7 +534,7 @@ static struct super_operations nilfs_sops = {
 	/* .drop_inode	  = nilfs_drop_inode, */
 	.delete_inode   = nilfs_delete_inode,
 	.put_super      = nilfs_put_super,
-	.write_super    = nilfs_write_super,
+	/* .write_super    = nilfs_write_super, */
 	.sync_fs        = nilfs_sync_fs,
 	/* .write_super_lockfs */
 	/* .unlockfs */
-- 
1.5.6.5