1 files changed, 47 insertions, 12 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 6409b3762995..8ed164eb9544 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 }
 };
 
@@ -225,7 +226,7 @@ xfs_mount_validate_sb(
                 return XFS_ERROR(EWRONGFS);
         }
 
-        if (!XFS_SB_GOOD_VERSION(sbp)) {
+        if (!xfs_sb_good_version(sbp)) {
                 xfs_fs_mount_cmn_err(flags, "bad version");
                 return XFS_ERROR(EWRONGFS);
         }
@@ -300,7 +301,7 @@ xfs_mount_validate_sb(
         /*
          * Version 1 directory format has never worked on Linux.
          */
-        if (unlikely(!XFS_SB_VERSION_HASDIRV2(sbp))) {
+        if (unlikely(!xfs_sb_version_hasdirv2(sbp))) {
                 xfs_fs_mount_cmn_err(flags,
                         "file system using version 1 directory format");
                 return XFS_ERROR(ENOSYS);
@@ -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);
 }
 
 /*
@@ -781,7 +783,7 @@ xfs_update_alignment(xfs_mount_t *mp, int mfsi_flags, __uint64_t *update_flags)
                  * Update superblock with new values
                  * and log changes
                  */
-                if (XFS_SB_VERSION_HASDALIGN(sbp)) {
+                if (xfs_sb_version_hasdalign(sbp)) {
                         if (sbp->sb_unit != mp->m_dalign) {
                                 sbp->sb_unit = mp->m_dalign;
                                 *update_flags |= XFS_SB_UNIT;
@@ -792,7 +794,7 @@ xfs_update_alignment(xfs_mount_t *mp, int mfsi_flags, __uint64_t *update_flags)
                         }
                 }
         } else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
-                    XFS_SB_VERSION_HASDALIGN(&mp->m_sb)) {
+                    xfs_sb_version_hasdalign(&mp->m_sb)) {
                         mp->m_dalign = sbp->sb_unit;
                         mp->m_swidth = sbp->sb_width;
         }
@@ -869,7 +871,7 @@ xfs_set_rw_sizes(xfs_mount_t *mp)
 STATIC void
 xfs_set_inoalignment(xfs_mount_t *mp)
 {
-        if (XFS_SB_VERSION_HASALIGN(&mp->m_sb) &&
+        if (xfs_sb_version_hasalign(&mp->m_sb) &&
             mp->m_sb.sb_inoalignmt >=
             XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
                 mp->m_inoalign_mask = mp->m_sb.sb_inoalignmt - 1;
@@ -970,6 +972,38 @@ xfs_mountfs(
         xfs_mount_common(mp, sbp);
 
         /*
+         * Check for a mismatched features2 values.  Older kernels
+         * read & wrote into the wrong sb offset for sb_features2
+         * on some platforms due to xfs_sb_t not being 64bit size aligned
+         * when sb_features2 was added, which made older superblock
+         * reading/writing routines swap it as a 64-bit value.
+         *
+         * For backwards compatibility, we make both slots equal.
+         *
+         * If we detect a mismatched field, we OR the set bits into the
+         * existing features2 field in case it has already been modified; we
+         * don't want to lose any features.  We then update the bad location
+         * with the ORed value so that older kernels will see any features2
+         * flags, and mark the two fields as needing updates once the
+         * transaction subsystem is online.
+         */
+        if (xfs_sb_has_mismatched_features2(sbp)) {
+                cmn_err(CE_WARN,
+                        "XFS: correcting sb_features alignment problem");
+                sbp->sb_features2 |= sbp->sb_bad_features2;
+                sbp->sb_bad_features2 = sbp->sb_features2;
+                update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;
+
+                /*
+                 * Re-check for ATTR2 in case it was found in bad_features2
+                 * slot.
+                 */
+                if (xfs_sb_version_hasattr2(&mp->m_sb))
+                        mp->m_flags |= XFS_MOUNT_ATTR2;
+
+        }
+
+        /*
          * 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 +1193,10 @@ 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
@@ -1875,16 +1908,18 @@ xfs_uuid_unmount(
 
 /*
  * Used to log changes to the superblock unit and width fields which could
- * be altered by the mount options. Only the first superblock is updated.
+ * be altered by the mount options, as well as any potential sb_features2
+ * fixup. 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,