xfs: move dax device handling into xfs_{alloc,free}_buftarg

Hide the DAX device lookup from the xfs_super.c code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/20211129102203.2243509-22-hch@lst.deSigned-off-by: Dan Williams <dan.j.williams@intel.com>

fs/xfs/xfs_buf.c

@@ -1892,6 +1892,7 @@ xfs_free_buftarg(
 	list_lru_destroy(&btp->bt_lru);
 
 	blkdev_issue_flush(btp->bt_bdev);
+	fs_put_dax(btp->bt_daxdev);
 
 	kmem_free(btp);
 }
@@ -1932,11 +1933,10 @@ xfs_setsize_buftarg_early(
 	return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev));
 }
 
-xfs_buftarg_t *
+struct xfs_buftarg *
 xfs_alloc_buftarg(
 	struct xfs_mount	*mp,
-	struct block_device	*bdev,
-	struct dax_device	*dax_dev)
+	struct block_device	*bdev)
 {
 	xfs_buftarg_t		*btp;
 
@@ -1945,7 +1945,7 @@ xfs_alloc_buftarg(
 	btp->bt_mount = mp;
 	btp->bt_dev =  bdev->bd_dev;
 	btp->bt_bdev = bdev;
-	btp->bt_daxdev = dax_dev;
+	btp->bt_daxdev = fs_dax_get_by_bdev(bdev);
 
 	/*
 	 * Buffer IO error rate limiting. Limit it to no more than 10 messages

fs/xfs/xfs_buf.h

@@ -338,8 +338,8 @@ xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 /*
  *	Handling of buftargs.
  */
-extern struct xfs_buftarg *xfs_alloc_buftarg(struct xfs_mount *,
-		struct block_device *, struct dax_device *);
+struct xfs_buftarg *xfs_alloc_buftarg(struct xfs_mount *mp,
+		struct block_device *bdev);
 extern void xfs_free_buftarg(struct xfs_buftarg *);
 extern void xfs_buftarg_wait(struct xfs_buftarg *);
 extern void xfs_buftarg_drain(struct xfs_buftarg *);

fs/xfs/xfs_super.c

@@ -391,26 +391,19 @@ 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->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->m_rtdev_targp);
 		xfs_blkdev_put(rtdev);
-		fs_put_dax(dax_rtdev);
 	}
 	xfs_free_buftarg(mp->m_ddev_targp);
-	fs_put_dax(dax_ddev);
 }
 
 /*
@@ -428,8 +421,6 @@ 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;
 
@@ -439,8 +430,7 @@ xfs_open_devices(
 	if (mp->m_logname) {
 		error = xfs_blkdev_get(mp, mp->m_logname, &logdev);
 		if (error)
-			goto out;
-		dax_logdev = fs_dax_get_by_bdev(logdev);
+			return error;
 	}
 
 	if (mp->m_rtname) {
@@ -454,25 +444,24 @@ 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, dax_ddev);
+	mp->m_ddev_targp = xfs_alloc_buftarg(mp, ddev);
 	if (!mp->m_ddev_targp)
 		goto out_close_rtdev;
 
 	if (rtdev) {
-		mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev, dax_rtdev);
+		mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev);
 		if (!mp->m_rtdev_targp)
 			goto out_free_ddev_targ;
 	}
 
 	if (logdev && logdev != ddev) {
-		mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev, dax_logdev);
+		mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev);
 		if (!mp->m_logdev_targp)
 			goto out_free_rtdev_targ;
 	} else {
@@ -488,14 +477,9 @@ xfs_open_devices(
 	xfs_free_buftarg(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;
 }