commit 486aff5e04823bb1e60c4045226eb244024b8420
author Dan Williams <dan.j.williams@intel.com> Thu Aug 24 15:12:50 2017 -0700
committer Dan Williams <dan.j.williams@intel.com> Thu Aug 31 09:31:47 2017 -0700
tree c0cc960b998086e92873d918f203a5e737e97db6
parent 78f35473508118df5ea04b9515ac3f1aaec0a980

xfs: perform dax_device lookup at mount

The ->iomap_begin() operation is a hot path, so cache the
fs_dax_get_by_host() result at mount time to avoid the incurring the
hash lookup overhead on a per-i/o basis.

Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

fs/xfs/xfs_super.c

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 38aaacd..ee4225c 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -714,17 +714,26 @@ STATIC void
 xfs_close_devices(
 	struct xfs_mount	*mp)
 {
+	struct dax_device *dax_ddev = mp->m_ddev_targp->bt_daxdev;
+
 	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp) {
 		struct block_device *logdev = mp->m_logdev_targp->bt_bdev;
+		struct dax_device *dax_logdev = mp->m_logdev_targp->bt_daxdev;
+
 		xfs_free_buftarg(mp, mp->m_logdev_targp);
 		xfs_blkdev_put(logdev);
+		fs_put_dax(dax_logdev);
 	}
 	if (mp->m_rtdev_targp) {
 		struct block_device *rtdev = mp->m_rtdev_targp->bt_bdev;
+		struct dax_device *dax_rtdev = mp->m_rtdev_targp->bt_daxdev;
+
 		xfs_free_buftarg(mp, mp->m_rtdev_targp);
 		xfs_blkdev_put(rtdev);
+		fs_put_dax(dax_rtdev);
 	}
 	xfs_free_buftarg(mp, mp->m_ddev_targp);
+	fs_put_dax(dax_ddev);
 }
 
 /*
@@ -742,6 +751,8 @@ xfs_open_devices(
 	struct xfs_mount	*mp)
 {
 	struct block_device	*ddev = mp->m_super->s_bdev;
+	struct dax_device	*dax_ddev = fs_dax_get_by_bdev(ddev);
+	struct dax_device	*dax_logdev = NULL, *dax_rtdev = NULL;
 	struct block_device	*logdev = NULL, *rtdev = NULL;
 	int			error;
 
@@ -752,6 +763,7 @@ xfs_open_devices(
 		error = xfs_blkdev_get(mp, mp->m_logname, &logdev);
 		if (error)
 			goto out;
+		dax_logdev = fs_dax_get_by_bdev(logdev);
 	}
 
 	if (mp->m_rtname) {
@@ -765,24 +777,25 @@ xfs_open_devices(
 			error = -EINVAL;
 			goto out_close_rtdev;
 		}
+		dax_rtdev = fs_dax_get_by_bdev(rtdev);
 	}
 
 	/*
 	 * Setup xfs_mount buffer target pointers
 	 */
 	error = -ENOMEM;
-	mp->m_ddev_targp = xfs_alloc_buftarg(mp, ddev);
+	mp->m_ddev_targp = xfs_alloc_buftarg(mp, ddev, dax_ddev);
 	if (!mp->m_ddev_targp)
 		goto out_close_rtdev;
 
 	if (rtdev) {
-		mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev);
+		mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev, dax_rtdev);
 		if (!mp->m_rtdev_targp)
 			goto out_free_ddev_targ;
 	}
 
 	if (logdev && logdev != ddev) {
-		mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev);
+		mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev, dax_logdev);
 		if (!mp->m_logdev_targp)
 			goto out_free_rtdev_targ;
 	} else {
@@ -798,10 +811,14 @@ xfs_open_devices(
 	xfs_free_buftarg(mp, mp->m_ddev_targp);
  out_close_rtdev:
 	xfs_blkdev_put(rtdev);
+	fs_put_dax(dax_rtdev);
  out_close_logdev:
-	if (logdev && logdev != ddev)
+	if (logdev && logdev != ddev) {
 		xfs_blkdev_put(logdev);
+		fs_put_dax(dax_logdev);
+	}
  out:
+	fs_put_dax(dax_ddev);
 	return error;
 }