xfs: remove shared supberlock feature checking

We reject any filesystem that is mounted with this feature bit set,
so we don't need to check for it anywhere else. Remove the function
for checking if the feature bit is set and any code that uses it.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

3 files changed, 6 insertions, 16 deletions

diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index b19b01576944..c31ac96349d2 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -84,8 +84,6 @@ xfs_fs_geometry(
                                 XFS_FSOP_GEOM_FLAGS_IALIGN : 0) |
                         (xfs_sb_version_hasdalign(&mp->m_sb) ?
                                 XFS_FSOP_GEOM_FLAGS_DALIGN : 0) |
-                        (xfs_sb_version_hasshared(&mp->m_sb) ?
-                                XFS_FSOP_GEOM_FLAGS_SHARED : 0) |
                         (xfs_sb_version_hasextflgbit(&mp->m_sb) ?
                                 XFS_FSOP_GEOM_FLAGS_EXTFLG : 0) |
                         (xfs_sb_version_hassector(&mp->m_sb) ?
diff --git a/fs/xfs/xfs_sb.c b/fs/xfs/xfs_sb.c
index de16dd558195..c3453b11f563 100644
--- a/fs/xfs/xfs_sb.c
+++ b/fs/xfs/xfs_sb.c
@@ -291,7 +291,8 @@ xfs_mount_validate_sb(
             (sbp->sb_imax_pct > 100 /* zero sb_imax_pct is valid */)    ||
             sbp->sb_dblocks == 0                                        ||
             sbp->sb_dblocks > XFS_MAX_DBLOCKS(sbp)                      ||
-            sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp))) {
+            sbp->sb_dblocks < XFS_MIN_DBLOCKS(sbp)                      ||
+            sbp->sb_shared_vn != 0)) {
                 xfs_notice(mp, "SB sanity check failed");
                 return XFS_ERROR(EFSCORRUPTED);
         }
diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index 822e62819741..86a964cc6925 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -51,11 +51,12 @@ struct xfs_trans;
 
 /*
  * Supported feature bit list is just all bits in the versionnum field because
- * we've used them all up and understand them all.
+ * we've used them all up and understand them all. Except, of course, for the
+ * shared superblock bit, which nobody knows what it does and so is unsupported.
  */
 #define XFS_SB_VERSION_OKBITS           \
-        (XFS_SB_VERSION_NUMBITS         | \
-         XFS_SB_VERSION_ALLFBITS)
+        ((XFS_SB_VERSION_NUMBITS | XFS_SB_VERSION_ALLFBITS) & \
+                ~XFS_SB_VERSION_SHAREDBIT)
 
 /*
  * There are two words to hold XFS "feature" bits: the original
@@ -341,10 +342,6 @@ static inline bool xfs_sb_good_v4_features(struct xfs_sb *sbp)
              (sbp->sb_features2 & ~XFS_SB_VERSION2_OKBITS)))
                 return false;
 
-        /* We don't support shared superblocks - nobody knows what it is */
-        if (sbp->sb_versionnum & XFS_SB_VERSION_SHAREDBIT)
-                return false;
-
         return true;
 }
 
@@ -397,12 +394,6 @@ static inline bool xfs_sb_version_hasdalign(struct xfs_sb *sbp)
         return (sbp->sb_versionnum & XFS_SB_VERSION_DALIGNBIT);
 }
 
-static inline bool xfs_sb_version_hasshared(struct xfs_sb *sbp)
-{
-        return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_4 &&
-                (sbp->sb_versionnum & XFS_SB_VERSION_SHAREDBIT);
-}
-
 static inline bool xfs_sb_version_haslogv2(struct xfs_sb *sbp)
 {
         return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 ||