[PATCH 2/2] xfs: implement the lazytime mount options

[Christoph Hellwig <hch@xxxxxx>]

Use the VFS dirty inode tracking for lazytime inodes only, and just
log them in ->dirty_inode.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/xfs_iops.c        |  5 +++++
 fs/xfs/xfs_super.c       | 23 +++++++++++++++++++++++
 fs/xfs/xfs_trans_inode.c |  8 ++++++++
 3 files changed, 36 insertions(+)

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 56475fcd76f2..0946a3baae6a 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -46,6 +46,7 @@
 #include <linux/security.h>
 #include <linux/iomap.h>
 #include <linux/slab.h>
+#include <linux/iversion.h>
 
 /*
  * Directories have different lock order w.r.t. mmap_sem compared to regular
@@ -1057,6 +1058,10 @@ xfs_vn_update_time(
 
 	trace_xfs_update_time(ip);
 
+	if ((inode->i_sb->s_flags & SB_LAZYTIME) &&
+	    !((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false)))
+		return generic_update_time(inode, now, flags);
+
 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
 	if (error)
 		return error;
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 7aba628dc527..20d53f125c35 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1007,6 +1007,28 @@ xfs_fs_destroy_inode(
 	xfs_inode_set_reclaim_tag(ip);
 }
 
+static void
+xfs_fs_dirty_inode(
+	struct inode			*inode,
+	int				flag)
+{
+	struct xfs_inode		*ip = XFS_I(inode);
+	struct xfs_mount		*mp = ip->i_mount;
+	struct xfs_trans		*tp;
+
+	if (!(inode->i_sb->s_flags & SB_LAZYTIME))
+		return;
+	if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME))
+		return;
+
+	if (xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp))
+		return;
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_TIMESTAMP);
+	xfs_trans_commit(tp);
+}
+
 /*
  * Slab object creation initialisation for the XFS inode.
  * This covers only the idempotent fields in the XFS inode;
@@ -1787,6 +1809,7 @@ xfs_fs_free_cached_objects(
 static const struct super_operations xfs_super_operations = {
 	.alloc_inode		= xfs_fs_alloc_inode,
 	.destroy_inode		= xfs_fs_destroy_inode,
+	.dirty_inode		= xfs_fs_dirty_inode,
 	.drop_inode		= xfs_fs_drop_inode,
 	.put_super		= xfs_fs_put_super,
 	.sync_fs		= xfs_fs_sync_fs,
diff --git a/fs/xfs/xfs_trans_inode.c b/fs/xfs/xfs_trans_inode.c
index fddacf9575df..769943fcc1f2 100644
--- a/fs/xfs/xfs_trans_inode.c
+++ b/fs/xfs/xfs_trans_inode.c
@@ -98,9 +98,17 @@ xfs_trans_log_inode(
 	xfs_inode_t	*ip,
 	uint		flags)
 {
+	struct inode	*inode = VFS_I(ip);
+
 	ASSERT(ip->i_itemp != NULL);
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 
+	if (inode->i_state & (I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED)) {
+		spin_lock(&inode->i_lock);
+		inode->i_state &= ~(I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED);
+		spin_unlock(&inode->i_lock);
+	}
+
 	/*
 	 * First time we log the inode in a transaction, bump the inode change
 	 * counter if it is configured for this to occur. While we have the
-- 
2.14.2