Ocfs2 devel - Mar 2015 - [PATCH V2] ocfs2: flush inode data to disk and free inode when i_count becomes zero

Disk inode deletion may be heavily delayed when one node unlink a file
after the same dentry is freed on another node(say N1) because of
memory shrink but inode is left in memory. This inode can only be
freed while N1 doing the orphan scan work.

However, N1 may skip orphan scan for several times because other nodes
may do the work earlier.  In our tests, it may take 1 hour on 4 nodes
cluster and it hurts the user experience. So we think the inode should
be freed after the data flushed to disk when i_count becomes zero to
avoid such circumstances.

Signed-off-by:  Joyce.xue <xuejiufei at huawei.com>
---
 fs/ocfs2/inode.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 3025c0d..7ff422d 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1191,17 +1191,19 @@ void ocfs2_evict_inode(struct inode *inode)
 int ocfs2_drop_inode(struct inode *inode)
 {
 	struct ocfs2_inode_info *oi = OCFS2_I(inode);
-	int res;
 
 	trace_ocfs2_drop_inode((unsigned long long)oi->ip_blkno,
 				inode->i_nlink, oi->ip_flags);
 
-	if (oi->ip_flags & OCFS2_INODE_MAYBE_ORPHANED)
-		res = 1;
-	else
-		res = generic_drop_inode(inode);
+	assert_spin_locked(&inode->i_lock);
+	inode->i_state |= I_WILL_FREE;
+	spin_unlock(&inode->i_lock);
+	write_inode_now(inode, 1);
+	spin_lock(&inode->i_lock);
+	WARN_ON(inode->i_state & I_NEW);
+	inode->i_state &= ~I_WILL_FREE;
 
-	return res;
+	return 1;
 }
 
 /*
-- 
1.8.4.3