1 files changed, 28 insertions, 6 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 99bab1e372b1..4e93c02faf24 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -44,7 +44,7 @@
 #include "xfs_quota.h"
 #include "xfs_fsops.h"
 
-STATIC void     xfs_mount_log_sbunit(xfs_mount_t *, __int64_t);
+STATIC void     xfs_mount_log_sb(xfs_mount_t *, __int64_t);
 STATIC int      xfs_uuid_mount(xfs_mount_t *);
 STATIC void     xfs_uuid_unmount(xfs_mount_t *mp);
 STATIC void     xfs_unmountfs_wait(xfs_mount_t *);
@@ -119,6 +119,7 @@ static const struct {
     { offsetof(xfs_sb_t, sb_logsectsize),0 },
     { offsetof(xfs_sb_t, sb_logsunit),   0 },
     { offsetof(xfs_sb_t, sb_features2),  0 },
+    { offsetof(xfs_sb_t, sb_bad_features2), 0 },
     { sizeof(xfs_sb_t),                  0 }
 };
 
@@ -449,6 +450,7 @@ xfs_sb_from_disk(
         to->sb_logsectsize = be16_to_cpu(from->sb_logsectsize);
         to->sb_logsunit = be32_to_cpu(from->sb_logsunit);
         to->sb_features2 = be32_to_cpu(from->sb_features2);
+        to->sb_bad_features2 = be32_to_cpu(from->sb_bad_features2);
 }
 
 /*
@@ -970,6 +972,26 @@ xfs_mountfs(
         xfs_mount_common(mp, sbp);
 
         /*
+         * Check for a bad features2 field alignment. This happened on
+         * some platforms due to xfs_sb_t not being 64bit size aligned
+         * when sb_features was added and hence the compiler put it in
+         * the wrong place.
+         *
+         * If we detect a bad field, we or the set bits into the existing
+         * features2 field in case it has already been modified and we
+         * don't want to lose any features. Zero the bad one and mark
+         * the two fields as needing updates once the transaction subsystem
+         * is online.
+         */
+        if (xfs_sb_has_bad_features2(sbp)) {
+                cmn_err(CE_WARN,
+                        "XFS: correcting sb_features alignment problem");
+                sbp->sb_features2 |= sbp->sb_bad_features2;
+                sbp->sb_bad_features2 = 0;
+                update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;
+        }
+
+        /*
          * Check if sb_agblocks is aligned at stripe boundary
          * If sb_agblocks is NOT aligned turn off m_dalign since
          * allocator alignment is within an ag, therefore ag has
@@ -1159,11 +1181,10 @@ xfs_mountfs(
         }
 
         /*
-         * If fs is not mounted readonly, then update the superblock
-         * unit and width changes.
+         * If fs is not mounted readonly, then update the superblock changes.
          */
         if (update_flags && !(mp->m_flags & XFS_MOUNT_RDONLY))
-                xfs_mount_log_sbunit(mp, update_flags);
+                xfs_mount_log_sb(mp, update_flags);
 
         /*
          * Initialise the XFS quota management subsystem for this mount
@@ -1878,13 +1899,14 @@ xfs_uuid_unmount(
  * be altered by the mount options. Only the first superblock is updated.
  */
 STATIC void
-xfs_mount_log_sbunit(
+xfs_mount_log_sb(
         xfs_mount_t     *mp,
         __int64_t       fields)
 {
         xfs_trans_t     *tp;
 
-        ASSERT(fields & (XFS_SB_UNIT|XFS_SB_WIDTH|XFS_SB_UUID));
+        ASSERT(fields & (XFS_SB_UNIT | XFS_SB_WIDTH | XFS_SB_UUID |
+                         XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2));
 
         tp = xfs_trans_alloc(mp, XFS_TRANS_SB_UNIT);
         if (xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,