[PATCH 7/7] xfs: re-enable XFS per-inode DAX

From: Ross Zwisler
Date: Mon Sep 25 2017 - 19:14:40 EST


Re-enable the XFS per-inode DAX flag, preventing S_DAX from changing when
any mappings are present.

Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
fs/xfs/xfs_ioctl.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 386b437..7a24dd5 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1012,12 +1012,10 @@ 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) || (ip->i_mount->m_flags & XFS_MOUNT_DAX))
inode->i_flags |= S_DAX;
else
inode->i_flags &= ~S_DAX;
-#endif
}

static bool
@@ -1049,6 +1047,8 @@ xfs_ioctl_setattr_xflags(
{
struct xfs_mount *mp = ip->i_mount;
uint64_t di_flags2;
+ struct address_space *mapping = VFS_I(ip)->i_mapping;
+ bool dax_changing;

/* Can't change realtime flag if any extents are allocated. */
if ((ip->i_d.di_nextents || ip->i_delayed_blks) &&
@@ -1084,10 +1084,23 @@ xfs_ioctl_setattr_xflags(
if (di_flags2 && ip->i_d.di_version < 3)
return -EINVAL;

+ dax_changing = xfs_is_dax_state_changing(fa->fsx_xflags, ip);
+ if (dax_changing) {
+ i_mmap_lock_read(mapping);
+ if (mapping_mapped(mapping)) {
+ i_mmap_unlock_read(mapping);
+ return -EBUSY;
+ }
+ }
+
ip->i_d.di_flags = xfs_flags2diflags(ip, fa->fsx_xflags);
ip->i_d.di_flags2 = di_flags2;

xfs_diflags_to_linux(ip);
+
+ if (dax_changing)
+ i_mmap_unlock_read(mapping);
+
xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
XFS_STATS_INC(mp, xs_ig_attrchg);
--
2.9.5