2 files changed, 62 insertions, 9 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,
diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index d3a59735009a..b1a83f8ec044 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -89,6 +89,7 @@ struct xfs_mount;
 
 /*
  * Superblock - in core version.  Must match the ondisk version below.
+ * Must be padded to 64 bit alignment.
  */
 typedef struct xfs_sb {
         __uint32_t      sb_magicnum;    /* magic number == XFS_SB_MAGIC */
@@ -145,10 +146,21 @@ typedef struct xfs_sb {
         __uint16_t      sb_logsectsize; /* sector size for the log, bytes */
         __uint32_t      sb_logsunit;    /* stripe unit size for the log */
         __uint32_t      sb_features2;   /* additional feature bits */
+
+        /*
+         * bad features2 field as a result of failing to pad the sb
+         * structure to 64 bits. Some machines will be using this field
+         * for features2 bits. Easiest just to mark it bad and not use
+         * it for anything else.
+         */
+        __uint32_t      sb_bad_features2;
+
+        /* must be padded to 64 bit alignment */
 } xfs_sb_t;
 
 /*
- * Superblock - on disk version.  Must match the in core version below.
+ * Superblock - on disk version.  Must match the in core version above.
+ * Must be padded to 64 bit alignment.
  */
 typedef struct xfs_dsb {
         __be32          sb_magicnum;    /* magic number == XFS_SB_MAGIC */
@@ -205,6 +217,15 @@ typedef struct xfs_dsb {
         __be16          sb_logsectsize; /* sector size for the log, bytes */
         __be32          sb_logsunit;    /* stripe unit size for the log */
         __be32          sb_features2;   /* additional feature bits */
+        /*
+         * bad features2 field as a result of failing to pad the sb
+         * structure to 64 bits. Some machines will be using this field
+         * for features2 bits. Easiest just to mark it bad and not use
+         * it for anything else.
+         */
+        __be32  sb_bad_features2;
+
+        /* must be padded to 64 bit alignment */
 } xfs_dsb_t;
 
 /*
@@ -223,7 +244,7 @@ typedef enum {
         XFS_SBS_GQUOTINO, XFS_SBS_QFLAGS, XFS_SBS_FLAGS, XFS_SBS_SHARED_VN,
         XFS_SBS_INOALIGNMT, XFS_SBS_UNIT, XFS_SBS_WIDTH, XFS_SBS_DIRBLKLOG,
         XFS_SBS_LOGSECTLOG, XFS_SBS_LOGSECTSIZE, XFS_SBS_LOGSUNIT,
-        XFS_SBS_FEATURES2,
+        XFS_SBS_FEATURES2, XFS_SBS_BAD_FEATURES2,
         XFS_SBS_FIELDCOUNT
 } xfs_sb_field_t;
 
@@ -248,13 +269,15 @@ typedef enum {
 #define XFS_SB_IFREE            XFS_SB_MVAL(IFREE)
 #define XFS_SB_FDBLOCKS         XFS_SB_MVAL(FDBLOCKS)
 #define XFS_SB_FEATURES2        XFS_SB_MVAL(FEATURES2)
+#define XFS_SB_BAD_FEATURES2    XFS_SB_MVAL(BAD_FEATURES2)
 #define XFS_SB_NUM_BITS         ((int)XFS_SBS_FIELDCOUNT)
 #define XFS_SB_ALL_BITS         ((1LL << XFS_SB_NUM_BITS) - 1)
 #define XFS_SB_MOD_BITS         \
         (XFS_SB_UUID | XFS_SB_ROOTINO | XFS_SB_RBMINO | XFS_SB_RSUMINO | \
          XFS_SB_VERSIONNUM | XFS_SB_UQUOTINO | XFS_SB_GQUOTINO | \
          XFS_SB_QFLAGS | XFS_SB_SHARED_VN | XFS_SB_UNIT | XFS_SB_WIDTH | \
-         XFS_SB_ICOUNT | XFS_SB_IFREE | XFS_SB_FDBLOCKS | XFS_SB_FEATURES2)
+         XFS_SB_ICOUNT | XFS_SB_IFREE | XFS_SB_FDBLOCKS | XFS_SB_FEATURES2 | \
+         XFS_SB_BAD_FEATURES2)
 
 
 /*
@@ -296,6 +319,14 @@ static inline int xfs_sb_good_version(xfs_sb_t *sbp)
 }
 #endif /* __KERNEL__ */
 
+/*
+ * Detect a bad features2 field
+ */
+static inline int xfs_sb_has_bad_features2(xfs_sb_t *sbp)
+{
+        return (sbp->sb_bad_features2 != 0);
+}
+
 static inline unsigned xfs_sb_version_tonew(unsigned v)
 {
         return ((((v) == XFS_SB_VERSION_1) ? \