linux-kernel - [PATCH V5 10/12] fs/xfs: Allow toggle of effective DAX flag

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Date:   Wed, 26 Feb 2020 21:24:40 -0800
From:   ira.weiny@...el.com
To:     linux-kernel@...r.kernel.org
Cc:     Ira Weiny <ira.weiny@...el.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>,
        Christoph Hellwig <hch@....de>,
        "Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH V5 10/12] fs/xfs: Allow toggle of effective DAX flag

From: Ira Weiny <ira.weiny@...el.com>

Now that locking of the inode aops is in place we can allow a DAX state
change.

Use the new xfs_inode_enable_dax() to set IS_DAX() as needed and update
the aops vector after the enabled state change.

Signed-off-by: Ira Weiny <ira.weiny@...el.com>

---
Changes from v4:
	Adjust for open coding of the aops lock

Changes from V3:
	Remove static branch stuff.
	Fix bugs found by Jeff by using xfs_inode_enable_dax()
	Condition xfs_ioctl_setattr_dax_invalidate() on CONFIG_FS_DAX

Changes from V2:
	Add in lock_dax_state_static_key static branch enabling.
	Rebase updates
---
 fs/xfs/xfs_inode.h |  2 ++
 fs/xfs/xfs_ioctl.c | 20 +++++++++++++++++---
 fs/xfs/xfs_iops.c  | 17 ++++++++++++-----
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 492e53992fa9..7d4968915dec 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -466,6 +466,8 @@ int	xfs_break_layouts(struct inode *inode, uint *iolock,
 /* from xfs_iops.c */
 extern void xfs_setup_inode(struct xfs_inode *ip);
 extern void xfs_setup_iops(struct xfs_inode *ip);
+extern void xfs_setup_a_ops(struct xfs_inode *ip);
+extern bool xfs_inode_enable_dax(struct xfs_inode *ip);
 
 /*
  * When setting up a newly allocated inode, we need to call
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 40ae791cfb41..38e91de44a6f 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1123,12 +1123,11 @@ xfs_diflags_to_linux(
 		inode->i_flags |= S_NOATIME;
 	else
 		inode->i_flags &= ~S_NOATIME;
-#if 0	/* disabled until the flag switching races are sorted out */
-	if (xflags & FS_XFLAG_DAX)
+
+	if (xfs_inode_enable_dax(ip))
 		inode->i_flags |= S_DAX;
 	else
 		inode->i_flags &= ~S_DAX;
-#endif
 }
 
 static int
@@ -1183,6 +1182,7 @@ xfs_ioctl_setattr_xflags(
  * so that the cache invalidation is atomic with respect to the DAX flag
  * manipulation.
  */
+#if defined(CONFIG_FS_DAX)
 static int
 xfs_ioctl_setattr_dax_invalidate(
 	struct xfs_inode	*ip,
@@ -1233,6 +1233,16 @@ xfs_ioctl_setattr_dax_invalidate(
 	return error;
 
 }
+#else /* !CONFIG_FS_DAX */
+static int
+xfs_ioctl_setattr_dax_invalidate(
+	struct xfs_inode	*ip,
+	struct fsxattr		*fa,
+	int			*join_flags)
+{
+	return 0;
+}
+#endif
 
 /*
  * Set up the transaction structure for the setattr operation, checking that we
@@ -1524,6 +1534,8 @@ xfs_ioctl_setattr(
 	else
 		ip->i_d.di_cowextsize = 0;
 
+	xfs_setup_a_ops(ip);
+
 	code = xfs_trans_commit(tp);
 
 	/*
@@ -1639,6 +1651,8 @@ xfs_ioc_setxflags(
 		goto out_drop_write;
 	}
 
+	xfs_setup_a_ops(ip);
+
 	error = xfs_trans_commit(tp);
 out_drop_write:
 	mnt_drop_write_file(filp);
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index ff711efc5247..8f023be39705 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1259,7 +1259,7 @@ xfs_inode_supports_dax(
 	return xfs_inode_buftarg(ip)->bt_daxdev != NULL;
 }
 
-STATIC bool
+bool
 xfs_inode_enable_dax(
 	struct xfs_inode *ip)
 {
@@ -1355,6 +1355,16 @@ xfs_setup_inode(
 	}
 }
 
+void xfs_setup_a_ops(struct xfs_inode *ip)
+{
+	struct inode		*inode = &ip->i_vnode;
+
+	if (IS_DAX(inode))
+		inode->i_mapping->a_ops = &xfs_dax_aops;
+	else
+		inode->i_mapping->a_ops = &xfs_address_space_operations;
+}
+
 void
 xfs_setup_iops(
 	struct xfs_inode	*ip)
@@ -1365,10 +1375,7 @@ xfs_setup_iops(
 	case S_IFREG:
 		inode->i_op = &xfs_inode_operations;
 		inode->i_fop = &xfs_file_operations;
-		if (IS_DAX(inode))
-			inode->i_mapping->a_ops = &xfs_dax_aops;
-		else
-			inode->i_mapping->a_ops = &xfs_address_space_operations;
+		xfs_setup_a_ops(ip);
 		break;
 	case S_IFDIR:
 		if (xfs_sb_version_hasasciici(&XFS_M(inode->i_sb)->m_sb))
-- 
2.21.0