xfs: recognize the reflink feature bit

Add the reflink feature flag to the set of recognized feature flags.
This enables users to write to reflink filesystems.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

2 files changed, 9 insertions, 1 deletions

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 5e04ea2aa902..f6547fc5e016 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -459,7 +459,8 @@ xfs_sb_has_compat_feature(
 #define XFS_SB_FEAT_RO_COMPAT_REFLINK  (1 << 2)         /* reflinked files */
 #define XFS_SB_FEAT_RO_COMPAT_ALL \
                 (XFS_SB_FEAT_RO_COMPAT_FINOBT | \
-                 XFS_SB_FEAT_RO_COMPAT_RMAPBT)
+                 XFS_SB_FEAT_RO_COMPAT_RMAPBT | \
+                 XFS_SB_FEAT_RO_COMPAT_REFLINK)
 #define XFS_SB_FEAT_RO_COMPAT_UNKNOWN   ~XFS_SB_FEAT_RO_COMPAT_ALL
 static inline bool
 xfs_sb_has_ro_compat_feature(
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 15b9fcd16c67..72bde2811bd7 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1614,6 +1614,9 @@ xfs_fs_fill_super(
                         "DAX unsupported by block device. Turning off DAX.");
                         mp->m_flags &= ~XFS_MOUNT_DAX;
                 }
+                if (xfs_sb_version_hasreflink(&mp->m_sb))
+                        xfs_alert(mp,
+                "DAX and reflink have not been tested together!");
         }
 
         if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
@@ -1627,6 +1630,10 @@ xfs_fs_fill_super(
         "EXPERIMENTAL reverse mapping btree feature enabled. Use at your own risk!");
         }
 
+        if (xfs_sb_version_hasreflink(&mp->m_sb))
+                xfs_alert(mp,
+        "EXPERIMENTAL reflink feature enabled. Use at your own risk!");
+
         error = xfs_mountfs(mp);
         if (error)
                 goto out_filestream_unmount;