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[PATCH 21/60] xfs: introduce xfs_sb.c for sharing with libxfs

To: xfs@xxxxxxxxxxx
Subject: [PATCH 21/60] xfs: introduce xfs_sb.c for sharing with libxfs
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 19 Jun 2013 14:50:29 +1000
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1371617468-32559-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1371617468-32559-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

xfs_mount.c is shared with userspace, but the only functions that
are shared are to do with physical superblock manipulations. This
means that less than 25% of the xfs_mount.c code is actually shared
with userspace. Move all the superblock functions to xfs_sb.c and
share that instead with libxfs.

Note that this will leave all the in-core transaction related
superblock counter modifications in xfs_mount.c as none of that is
shared with userspace. With a few more small changes, xfs_mount.h
won't need to be shared with userspace anymore, either.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/Makefile    |    3 +-
 fs/xfs/xfs_mount.c |  828 ++++++----------------------------------------------
 fs/xfs/xfs_mount.h |   19 +-
 fs/xfs/xfs_sb.c    |  716 +++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_sb.h    |   19 ++
 5 files changed, 823 insertions(+), 762 deletions(-)
 create mode 100644 fs/xfs/xfs_sb.c

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 8567bd6..ba7d292 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -49,6 +49,7 @@ xfs-y                         += xfs_aops.o \
                                   xfs_iops.o \
                                   xfs_itable.o \
                                   xfs_message.o \
+                                  xfs_mount.o \
                                   xfs_mru_cache.o \
                                   xfs_rename.o \
                                   xfs_super.o \
@@ -78,7 +79,7 @@ xfs-y                         += xfs_alloc.o \
                                   xfs_icreate_item.o \
                                   xfs_inode.o \
                                   xfs_log_recover.o \
-                                  xfs_mount.o \
+                                  xfs_sb.o \
                                   xfs_symlink.o \
                                   xfs_trans.o
 
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index e7253e2..5117587 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -61,69 +61,6 @@ STATIC void  xfs_icsb_disable_counter(xfs_mount_t *, 
xfs_sb_field_t);
 #define xfs_icsb_balance_counter_locked(mp, a, b)      do { } while (0)
 #endif
 
-static const struct {
-       short offset;
-       short type;     /* 0 = integer
-                        * 1 = binary / string (no translation)
-                        */
-} xfs_sb_info[] = {
-    { offsetof(xfs_sb_t, sb_magicnum),   0 },
-    { offsetof(xfs_sb_t, sb_blocksize),  0 },
-    { offsetof(xfs_sb_t, sb_dblocks),    0 },
-    { offsetof(xfs_sb_t, sb_rblocks),    0 },
-    { offsetof(xfs_sb_t, sb_rextents),   0 },
-    { offsetof(xfs_sb_t, sb_uuid),       1 },
-    { offsetof(xfs_sb_t, sb_logstart),   0 },
-    { offsetof(xfs_sb_t, sb_rootino),    0 },
-    { offsetof(xfs_sb_t, sb_rbmino),     0 },
-    { offsetof(xfs_sb_t, sb_rsumino),    0 },
-    { offsetof(xfs_sb_t, sb_rextsize),   0 },
-    { offsetof(xfs_sb_t, sb_agblocks),   0 },
-    { offsetof(xfs_sb_t, sb_agcount),    0 },
-    { offsetof(xfs_sb_t, sb_rbmblocks),  0 },
-    { offsetof(xfs_sb_t, sb_logblocks),  0 },
-    { offsetof(xfs_sb_t, sb_versionnum), 0 },
-    { offsetof(xfs_sb_t, sb_sectsize),   0 },
-    { offsetof(xfs_sb_t, sb_inodesize),  0 },
-    { offsetof(xfs_sb_t, sb_inopblock),  0 },
-    { offsetof(xfs_sb_t, sb_fname[0]),   1 },
-    { offsetof(xfs_sb_t, sb_blocklog),   0 },
-    { offsetof(xfs_sb_t, sb_sectlog),    0 },
-    { offsetof(xfs_sb_t, sb_inodelog),   0 },
-    { offsetof(xfs_sb_t, sb_inopblog),   0 },
-    { offsetof(xfs_sb_t, sb_agblklog),   0 },
-    { offsetof(xfs_sb_t, sb_rextslog),   0 },
-    { offsetof(xfs_sb_t, sb_inprogress), 0 },
-    { offsetof(xfs_sb_t, sb_imax_pct),   0 },
-    { offsetof(xfs_sb_t, sb_icount),     0 },
-    { offsetof(xfs_sb_t, sb_ifree),      0 },
-    { offsetof(xfs_sb_t, sb_fdblocks),   0 },
-    { offsetof(xfs_sb_t, sb_frextents),  0 },
-    { offsetof(xfs_sb_t, sb_uquotino),   0 },
-    { offsetof(xfs_sb_t, sb_gquotino),   0 },
-    { offsetof(xfs_sb_t, sb_qflags),     0 },
-    { offsetof(xfs_sb_t, sb_flags),      0 },
-    { offsetof(xfs_sb_t, sb_shared_vn),  0 },
-    { offsetof(xfs_sb_t, sb_inoalignmt), 0 },
-    { offsetof(xfs_sb_t, sb_unit),      0 },
-    { offsetof(xfs_sb_t, sb_width),     0 },
-    { offsetof(xfs_sb_t, sb_dirblklog),         0 },
-    { offsetof(xfs_sb_t, sb_logsectlog), 0 },
-    { 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 },
-    { offsetof(xfs_sb_t, sb_features_compat), 0 },
-    { offsetof(xfs_sb_t, sb_features_ro_compat), 0 },
-    { offsetof(xfs_sb_t, sb_features_incompat), 0 },
-    { offsetof(xfs_sb_t, sb_features_log_incompat), 0 },
-    { offsetof(xfs_sb_t, sb_crc),       0 },
-    { offsetof(xfs_sb_t, sb_pad),       0 },
-    { offsetof(xfs_sb_t, sb_pquotino),  0 },
-    { offsetof(xfs_sb_t, sb_lsn),       0 },
-    { sizeof(xfs_sb_t),                         0 }
-};
-
 static DEFINE_MUTEX(xfs_uuid_table_mutex);
 static int xfs_uuid_table_size;
 static uuid_t *xfs_uuid_table;
@@ -199,64 +136,6 @@ xfs_uuid_unmount(
 }
 
 
-/*
- * Reference counting access wrappers to the perag structures.
- * Because we never free per-ag structures, the only thing we
- * have to protect against changes is the tree structure itself.
- */
-struct xfs_perag *
-xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
-{
-       struct xfs_perag        *pag;
-       int                     ref = 0;
-
-       rcu_read_lock();
-       pag = radix_tree_lookup(&mp->m_perag_tree, agno);
-       if (pag) {
-               ASSERT(atomic_read(&pag->pag_ref) >= 0);
-               ref = atomic_inc_return(&pag->pag_ref);
-       }
-       rcu_read_unlock();
-       trace_xfs_perag_get(mp, agno, ref, _RET_IP_);
-       return pag;
-}
-
-/*
- * search from @first to find the next perag with the given tag set.
- */
-struct xfs_perag *
-xfs_perag_get_tag(
-       struct xfs_mount        *mp,
-       xfs_agnumber_t          first,
-       int                     tag)
-{
-       struct xfs_perag        *pag;
-       int                     found;
-       int                     ref;
-
-       rcu_read_lock();
-       found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-                                       (void **)&pag, first, 1, tag);
-       if (found <= 0) {
-               rcu_read_unlock();
-               return NULL;
-       }
-       ref = atomic_inc_return(&pag->pag_ref);
-       rcu_read_unlock();
-       trace_xfs_perag_get_tag(mp, pag->pag_agno, ref, _RET_IP_);
-       return pag;
-}
-
-void
-xfs_perag_put(struct xfs_perag *pag)
-{
-       int     ref;
-
-       ASSERT(atomic_read(&pag->pag_ref) > 0);
-       ref = atomic_dec_return(&pag->pag_ref);
-       trace_xfs_perag_put(pag->pag_mount, pag->pag_agno, ref, _RET_IP_);
-}
-
 STATIC void
 __xfs_free_perag(
        struct rcu_head *head)
@@ -287,198 +166,6 @@ xfs_free_perag(
        }
 }
 
-/*
- * Check size of device based on the (data/realtime) block count.
- * Note: this check is used by the growfs code as well as mount.
- */
-int
-xfs_sb_validate_fsb_count(
-       xfs_sb_t        *sbp,
-       __uint64_t      nblocks)
-{
-       ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
-       ASSERT(sbp->sb_blocklog >= BBSHIFT);
-
-#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
-       if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
-               return EFBIG;
-#else                  /* Limited by UINT_MAX of sectors */
-       if (nblocks << (sbp->sb_blocklog - BBSHIFT) > UINT_MAX)
-               return EFBIG;
-#endif
-       return 0;
-}
-
-/*
- * Check the validity of the SB found.
- */
-STATIC int
-xfs_mount_validate_sb(
-       xfs_mount_t     *mp,
-       xfs_sb_t        *sbp,
-       bool            check_inprogress,
-       bool            check_version)
-{
-
-       /*
-        * If the log device and data device have the
-        * same device number, the log is internal.
-        * Consequently, the sb_logstart should be non-zero.  If
-        * we have a zero sb_logstart in this case, we may be trying to mount
-        * a volume filesystem in a non-volume manner.
-        */
-       if (sbp->sb_magicnum != XFS_SB_MAGIC) {
-               xfs_warn(mp, "bad magic number");
-               return XFS_ERROR(EWRONGFS);
-       }
-
-
-       if (!xfs_sb_good_version(sbp)) {
-               xfs_warn(mp, "bad version");
-               return XFS_ERROR(EWRONGFS);
-       }
-
-       /*
-        * Version 5 superblock feature mask validation. Reject combinations the
-        * kernel cannot support up front before checking anything else. For
-        * write validation, we don't need to check feature masks.
-        */
-       if (check_version && XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) {
-               xfs_alert(mp,
-"Version 5 superblock detected. This kernel has EXPERIMENTAL support 
enabled!\n"
-"Use of these features in this kernel is at your own risk!");
-
-               if (xfs_sb_has_compat_feature(sbp,
-                                       XFS_SB_FEAT_COMPAT_UNKNOWN)) {
-                       xfs_warn(mp,
-"Superblock has unknown compatible features (0x%x) enabled.\n"
-"Using a more recent kernel is recommended.",
-                               (sbp->sb_features_compat &
-                                               XFS_SB_FEAT_COMPAT_UNKNOWN));
-               }
-
-               if (xfs_sb_has_ro_compat_feature(sbp,
-                                       XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
-                       xfs_alert(mp,
-"Superblock has unknown read-only compatible features (0x%x) enabled.",
-                               (sbp->sb_features_ro_compat &
-                                               XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
-                       if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
-                               xfs_warn(mp,
-"Attempted to mount read-only compatible filesystem read-write.\n"
-"Filesystem can only be safely mounted read only.");
-                               return XFS_ERROR(EINVAL);
-                       }
-               }
-               if (xfs_sb_has_incompat_feature(sbp,
-                                       XFS_SB_FEAT_INCOMPAT_UNKNOWN)) {
-                       xfs_warn(mp,
-"Superblock has unknown incompatible features (0x%x) enabled.\n"
-"Filesystem can not be safely mounted by this kernel.",
-                               (sbp->sb_features_incompat &
-                                               XFS_SB_FEAT_INCOMPAT_UNKNOWN));
-                       return XFS_ERROR(EINVAL);
-               }
-       }
-
-       if (unlikely(
-           sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
-               xfs_warn(mp,
-               "filesystem is marked as having an external log; "
-               "specify logdev on the mount command line.");
-               return XFS_ERROR(EINVAL);
-       }
-
-       if (unlikely(
-           sbp->sb_logstart != 0 && mp->m_logdev_targp != mp->m_ddev_targp)) {
-               xfs_warn(mp,
-               "filesystem is marked as having an internal log; "
-               "do not specify logdev on the mount command line.");
-               return XFS_ERROR(EINVAL);
-       }
-
-       /*
-        * More sanity checking.  Most of these were stolen directly from
-        * xfs_repair.
-        */
-       if (unlikely(
-           sbp->sb_agcount <= 0                                        ||
-           sbp->sb_sectsize < XFS_MIN_SECTORSIZE                       ||
-           sbp->sb_sectsize > XFS_MAX_SECTORSIZE                       ||
-           sbp->sb_sectlog < XFS_MIN_SECTORSIZE_LOG                    ||
-           sbp->sb_sectlog > XFS_MAX_SECTORSIZE_LOG                    ||
-           sbp->sb_sectsize != (1 << sbp->sb_sectlog)                  ||
-           sbp->sb_blocksize < XFS_MIN_BLOCKSIZE                       ||
-           sbp->sb_blocksize > XFS_MAX_BLOCKSIZE                       ||
-           sbp->sb_blocklog < XFS_MIN_BLOCKSIZE_LOG                    ||
-           sbp->sb_blocklog > XFS_MAX_BLOCKSIZE_LOG                    ||
-           sbp->sb_blocksize != (1 << sbp->sb_blocklog)                ||
-           sbp->sb_inodesize < XFS_DINODE_MIN_SIZE                     ||
-           sbp->sb_inodesize > XFS_DINODE_MAX_SIZE                     ||
-           sbp->sb_inodelog < XFS_DINODE_MIN_LOG                       ||
-           sbp->sb_inodelog > XFS_DINODE_MAX_LOG                       ||
-           sbp->sb_inodesize != (1 << sbp->sb_inodelog)                ||
-           (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)   ||
-           (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)  ||
-           (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)  ||
-           (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))) {
-               XFS_CORRUPTION_ERROR("SB sanity check failed",
-                               XFS_ERRLEVEL_LOW, mp, sbp);
-               return XFS_ERROR(EFSCORRUPTED);
-       }
-
-       /*
-        * Until this is fixed only page-sized or smaller data blocks work.
-        */
-       if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {
-               xfs_warn(mp,
-               "File system with blocksize %d bytes. "
-               "Only pagesize (%ld) or less will currently work.",
-                               sbp->sb_blocksize, PAGE_SIZE);
-               return XFS_ERROR(ENOSYS);
-       }
-
-       /*
-        * Currently only very few inode sizes are supported.
-        */
-       switch (sbp->sb_inodesize) {
-       case 256:
-       case 512:
-       case 1024:
-       case 2048:
-               break;
-       default:
-               xfs_warn(mp, "inode size of %d bytes not supported",
-                               sbp->sb_inodesize);
-               return XFS_ERROR(ENOSYS);
-       }
-
-       if (xfs_sb_validate_fsb_count(sbp, sbp->sb_dblocks) ||
-           xfs_sb_validate_fsb_count(sbp, sbp->sb_rblocks)) {
-               xfs_warn(mp,
-               "file system too large to be mounted on this system.");
-               return XFS_ERROR(EFBIG);
-       }
-
-       if (check_inprogress && sbp->sb_inprogress) {
-               xfs_warn(mp, "Offline file system operation in progress!");
-               return XFS_ERROR(EFSCORRUPTED);
-       }
-
-       /*
-        * Version 1 directory format has never worked on Linux.
-        */
-       if (unlikely(!xfs_sb_version_hasdirv2(sbp))) {
-               xfs_warn(mp, "file system using version 1 directory format");
-               return XFS_ERROR(ENOSYS);
-       }
-
-       return 0;
-}
-
 int
 xfs_initialize_perag(
        xfs_mount_t     *mp,
@@ -563,241 +250,114 @@ out_unwind:
        return error;
 }
 
-void
-xfs_sb_from_disk(
-       struct xfs_sb   *to,
-       xfs_dsb_t       *from)
-{
-       to->sb_magicnum = be32_to_cpu(from->sb_magicnum);
-       to->sb_blocksize = be32_to_cpu(from->sb_blocksize);
-       to->sb_dblocks = be64_to_cpu(from->sb_dblocks);
-       to->sb_rblocks = be64_to_cpu(from->sb_rblocks);
-       to->sb_rextents = be64_to_cpu(from->sb_rextents);
-       memcpy(&to->sb_uuid, &from->sb_uuid, sizeof(to->sb_uuid));
-       to->sb_logstart = be64_to_cpu(from->sb_logstart);
-       to->sb_rootino = be64_to_cpu(from->sb_rootino);
-       to->sb_rbmino = be64_to_cpu(from->sb_rbmino);
-       to->sb_rsumino = be64_to_cpu(from->sb_rsumino);
-       to->sb_rextsize = be32_to_cpu(from->sb_rextsize);
-       to->sb_agblocks = be32_to_cpu(from->sb_agblocks);
-       to->sb_agcount = be32_to_cpu(from->sb_agcount);
-       to->sb_rbmblocks = be32_to_cpu(from->sb_rbmblocks);
-       to->sb_logblocks = be32_to_cpu(from->sb_logblocks);
-       to->sb_versionnum = be16_to_cpu(from->sb_versionnum);
-       to->sb_sectsize = be16_to_cpu(from->sb_sectsize);
-       to->sb_inodesize = be16_to_cpu(from->sb_inodesize);
-       to->sb_inopblock = be16_to_cpu(from->sb_inopblock);
-       memcpy(&to->sb_fname, &from->sb_fname, sizeof(to->sb_fname));
-       to->sb_blocklog = from->sb_blocklog;
-       to->sb_sectlog = from->sb_sectlog;
-       to->sb_inodelog = from->sb_inodelog;
-       to->sb_inopblog = from->sb_inopblog;
-       to->sb_agblklog = from->sb_agblklog;
-       to->sb_rextslog = from->sb_rextslog;
-       to->sb_inprogress = from->sb_inprogress;
-       to->sb_imax_pct = from->sb_imax_pct;
-       to->sb_icount = be64_to_cpu(from->sb_icount);
-       to->sb_ifree = be64_to_cpu(from->sb_ifree);
-       to->sb_fdblocks = be64_to_cpu(from->sb_fdblocks);
-       to->sb_frextents = be64_to_cpu(from->sb_frextents);
-       to->sb_uquotino = be64_to_cpu(from->sb_uquotino);
-       to->sb_gquotino = be64_to_cpu(from->sb_gquotino);
-       to->sb_qflags = be16_to_cpu(from->sb_qflags);
-       to->sb_flags = from->sb_flags;
-       to->sb_shared_vn = from->sb_shared_vn;
-       to->sb_inoalignmt = be32_to_cpu(from->sb_inoalignmt);
-       to->sb_unit = be32_to_cpu(from->sb_unit);
-       to->sb_width = be32_to_cpu(from->sb_width);
-       to->sb_dirblklog = from->sb_dirblklog;
-       to->sb_logsectlog = from->sb_logsectlog;
-       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);
-       to->sb_features_compat = be32_to_cpu(from->sb_features_compat);
-       to->sb_features_ro_compat = be32_to_cpu(from->sb_features_ro_compat);
-       to->sb_features_incompat = be32_to_cpu(from->sb_features_incompat);
-       to->sb_features_log_incompat =
-                               be32_to_cpu(from->sb_features_log_incompat);
-       to->sb_pad = 0;
-       to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
-       to->sb_lsn = be64_to_cpu(from->sb_lsn);
-}
-
 /*
- * Copy in core superblock to ondisk one.
- *
- * The fields argument is mask of superblock fields to copy.
+ * Update alignment values based on mount options and sb values
  */
-void
-xfs_sb_to_disk(
-       xfs_dsb_t       *to,
-       xfs_sb_t        *from,
-       __int64_t       fields)
+STATIC int
+xfs_update_alignment(xfs_mount_t *mp)
 {
-       xfs_caddr_t     to_ptr = (xfs_caddr_t)to;
-       xfs_caddr_t     from_ptr = (xfs_caddr_t)from;
-       xfs_sb_field_t  f;
-       int             first;
-       int             size;
-
-       ASSERT(fields);
-       if (!fields)
-               return;
-
-       while (fields) {
-               f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
-               first = xfs_sb_info[f].offset;
-               size = xfs_sb_info[f + 1].offset - first;
-
-               ASSERT(xfs_sb_info[f].type == 0 || xfs_sb_info[f].type == 1);
+       xfs_sb_t        *sbp = &(mp->m_sb);
 
-               if (size == 1 || xfs_sb_info[f].type == 1) {
-                       memcpy(to_ptr + first, from_ptr + first, size);
+       if (mp->m_dalign) {
+               /*
+                * If stripe unit and stripe width are not multiples
+                * of the fs blocksize turn off alignment.
+                */
+               if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
+                   (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
+                       if (mp->m_flags & XFS_MOUNT_RETERR) {
+                               xfs_warn(mp, "alignment check failed: "
+                                        "(sunit/swidth vs. blocksize)");
+                               return XFS_ERROR(EINVAL);
+                       }
+                       mp->m_dalign = mp->m_swidth = 0;
                } else {
-                       switch (size) {
-                       case 2:
-                               *(__be16 *)(to_ptr + first) =
-                                       cpu_to_be16(*(__u16 *)(from_ptr + 
first));
-                               break;
-                       case 4:
-                               *(__be32 *)(to_ptr + first) =
-                                       cpu_to_be32(*(__u32 *)(from_ptr + 
first));
-                               break;
-                       case 8:
-                               *(__be64 *)(to_ptr + first) =
-                                       cpu_to_be64(*(__u64 *)(from_ptr + 
first));
-                               break;
-                       default:
-                               ASSERT(0);
+                       /*
+                        * Convert the stripe unit and width to FSBs.
+                        */
+                       mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
+                       if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
+                               if (mp->m_flags & XFS_MOUNT_RETERR) {
+                                       xfs_warn(mp, "alignment check failed: "
+                                                "(sunit/swidth vs. ag size)");
+                                       return XFS_ERROR(EINVAL);
+                               }
+                               xfs_warn(mp,
+               "stripe alignment turned off: sunit(%d)/swidth(%d) "
+               "incompatible with agsize(%d)",
+                                       mp->m_dalign, mp->m_swidth,
+                                       sbp->sb_agblocks);
+
+                               mp->m_dalign = 0;
+                               mp->m_swidth = 0;
+                       } else if (mp->m_dalign) {
+                               mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
+                       } else {
+                               if (mp->m_flags & XFS_MOUNT_RETERR) {
+                                       xfs_warn(mp, "alignment check failed: "
+                                               "sunit(%d) less than bsize(%d)",
+                                               mp->m_dalign,
+                                               mp->m_blockmask +1);
+                                       return XFS_ERROR(EINVAL);
+                               }
+                               mp->m_swidth = 0;
                        }
                }
 
-               fields &= ~(1LL << f);
-       }
-}
-
-static int
-xfs_sb_verify(
-       struct xfs_buf  *bp,
-       bool            check_version)
-{
-       struct xfs_mount *mp = bp->b_target->bt_mount;
-       struct xfs_sb   sb;
-
-       xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp));
-
-       /*
-        * Only check the in progress field for the primary superblock as
-        * mkfs.xfs doesn't clear it from secondary superblocks.
-        */
-       return xfs_mount_validate_sb(mp, &sb, bp->b_bn == XFS_SB_DADDR,
-                                    check_version);
-}
-
-/*
- * If the superblock has the CRC feature bit set or the CRC field is non-null,
- * check that the CRC is valid.  We check the CRC field is non-null because a
- * single bit error could clear the feature bit and unused parts of the
- * superblock are supposed to be zero. Hence a non-null crc field indicates 
that
- * we've potentially lost a feature bit and we should check it anyway.
- */
-static void
-xfs_sb_read_verify(
-       struct xfs_buf  *bp)
-{
-       struct xfs_mount *mp = bp->b_target->bt_mount;
-       struct xfs_dsb  *dsb = XFS_BUF_TO_SBP(bp);
-       int             error;
-
-       /*
-        * open code the version check to avoid needing to convert the entire
-        * superblock from disk order just to check the version number
-        */
-       if (dsb->sb_magicnum == cpu_to_be32(XFS_SB_MAGIC) &&
-           (((be16_to_cpu(dsb->sb_versionnum) & XFS_SB_VERSION_NUMBITS) ==
-                                               XFS_SB_VERSION_5) ||
-            dsb->sb_crc != 0)) {
-
-               if (!xfs_verify_cksum(bp->b_addr, be16_to_cpu(dsb->sb_sectsize),
-                                     offsetof(struct xfs_sb, sb_crc))) {
-                       error = EFSCORRUPTED;
-                       goto out_error;
+               /*
+                * Update superblock with new values
+                * and log changes
+                */
+               if (xfs_sb_version_hasdalign(sbp)) {
+                       if (sbp->sb_unit != mp->m_dalign) {
+                               sbp->sb_unit = mp->m_dalign;
+                               mp->m_update_flags |= XFS_SB_UNIT;
+                       }
+                       if (sbp->sb_width != mp->m_swidth) {
+                               sbp->sb_width = mp->m_swidth;
+                               mp->m_update_flags |= XFS_SB_WIDTH;
+                       }
                }
+       } else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
+                   xfs_sb_version_hasdalign(&mp->m_sb)) {
+                       mp->m_dalign = sbp->sb_unit;
+                       mp->m_swidth = sbp->sb_width;
        }
-       error = xfs_sb_verify(bp, true);
 
-out_error:
-       if (error) {
-               XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, 
bp->b_addr);
-               xfs_buf_ioerror(bp, error);
-       }
+       return 0;
 }
 
 /*
- * We may be probed for a filesystem match, so we may not want to emit
- * messages when the superblock buffer is not actually an XFS superblock.
- * If we find an XFS superblock, the run a normal, noisy mount because we are
- * really going to mount it and want to know about errors.
+ * Check size of device based on the (data/realtime) block count.
+ * Note: this check is used by the growfs code as well as mount.
  */
-static void
-xfs_sb_quiet_read_verify(
-       struct xfs_buf  *bp)
-{
-       struct xfs_dsb  *dsb = XFS_BUF_TO_SBP(bp);
-
-
-       if (dsb->sb_magicnum == cpu_to_be32(XFS_SB_MAGIC)) {
-               /* XFS filesystem, verify noisily! */
-               xfs_sb_read_verify(bp);
-               return;
-       }
-       /* quietly fail */
-       xfs_buf_ioerror(bp, EWRONGFS);
-}
-
-static void
-xfs_sb_write_verify(
-       struct xfs_buf          *bp)
+int
+xfs_sb_validate_fsb_count(
+       xfs_sb_t        *sbp,
+       __uint64_t      nblocks)
 {
-       struct xfs_mount        *mp = bp->b_target->bt_mount;
-       struct xfs_buf_log_item *bip = bp->b_fspriv;
-       int                     error;
-
-       error = xfs_sb_verify(bp, false);
-       if (error) {
-               XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, 
bp->b_addr);
-               xfs_buf_ioerror(bp, error);
-               return;
-       }
-
-       if (!xfs_sb_version_hascrc(&mp->m_sb))
-               return;
-
-       if (bip)
-               XFS_BUF_TO_SBP(bp)->sb_lsn = cpu_to_be64(bip->bli_item.li_lsn);
+       ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
+       ASSERT(sbp->sb_blocklog >= BBSHIFT);
 
-       xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
-                        offsetof(struct xfs_sb, sb_crc));
+#if XFS_BIG_BLKNOS     /* Limited by ULONG_MAX of page cache index */
+       if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
+               return EFBIG;
+#else                  /* Limited by UINT_MAX of sectors */
+       if (nblocks << (sbp->sb_blocklog - BBSHIFT) > UINT_MAX)
+               return EFBIG;
+#endif
+       return 0;
 }
 
-const struct xfs_buf_ops xfs_sb_buf_ops = {
-       .verify_read = xfs_sb_read_verify,
-       .verify_write = xfs_sb_write_verify,
-};
-
-static const struct xfs_buf_ops xfs_sb_quiet_buf_ops = {
-       .verify_read = xfs_sb_quiet_read_verify,
-       .verify_write = xfs_sb_write_verify,
-};
-
 /*
  * xfs_readsb
  *
  * Does the initial read of the superblock.
  */
 int
-xfs_readsb(xfs_mount_t *mp, int flags)
+xfs_readsb(
+       struct xfs_mount *mp,
+       int             flags)
 {
        unsigned int    sector_size;
        struct xfs_buf  *bp;
@@ -873,184 +433,6 @@ release_buf:
        return error;
 }
 
-
-/*
- * xfs_mount_common
- *
- * Mount initialization code establishing various mount
- * fields from the superblock associated with the given
- * mount structure
- */
-STATIC void
-xfs_mount_common(xfs_mount_t *mp, xfs_sb_t *sbp)
-{
-       mp->m_agfrotor = mp->m_agirotor = 0;
-       spin_lock_init(&mp->m_agirotor_lock);
-       mp->m_maxagi = mp->m_sb.sb_agcount;
-       mp->m_blkbit_log = sbp->sb_blocklog + XFS_NBBYLOG;
-       mp->m_blkbb_log = sbp->sb_blocklog - BBSHIFT;
-       mp->m_sectbb_log = sbp->sb_sectlog - BBSHIFT;
-       mp->m_agno_log = xfs_highbit32(sbp->sb_agcount - 1) + 1;
-       mp->m_agino_log = sbp->sb_inopblog + sbp->sb_agblklog;
-       mp->m_blockmask = sbp->sb_blocksize - 1;
-       mp->m_blockwsize = sbp->sb_blocksize >> XFS_WORDLOG;
-       mp->m_blockwmask = mp->m_blockwsize - 1;
-
-       mp->m_alloc_mxr[0] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 1);
-       mp->m_alloc_mxr[1] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 0);
-       mp->m_alloc_mnr[0] = mp->m_alloc_mxr[0] / 2;
-       mp->m_alloc_mnr[1] = mp->m_alloc_mxr[1] / 2;
-
-       mp->m_inobt_mxr[0] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 1);
-       mp->m_inobt_mxr[1] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 0);
-       mp->m_inobt_mnr[0] = mp->m_inobt_mxr[0] / 2;
-       mp->m_inobt_mnr[1] = mp->m_inobt_mxr[1] / 2;
-
-       mp->m_bmap_dmxr[0] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 1);
-       mp->m_bmap_dmxr[1] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 0);
-       mp->m_bmap_dmnr[0] = mp->m_bmap_dmxr[0] / 2;
-       mp->m_bmap_dmnr[1] = mp->m_bmap_dmxr[1] / 2;
-
-       mp->m_bsize = XFS_FSB_TO_BB(mp, 1);
-       mp->m_ialloc_inos = (int)MAX((__uint16_t)XFS_INODES_PER_CHUNK,
-                                       sbp->sb_inopblock);
-       mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
-}
-
-/*
- * xfs_initialize_perag_data
- *
- * Read in each per-ag structure so we can count up the number of
- * allocated inodes, free inodes and used filesystem blocks as this
- * information is no longer persistent in the superblock. Once we have
- * this information, write it into the in-core superblock structure.
- */
-STATIC int
-xfs_initialize_perag_data(xfs_mount_t *mp, xfs_agnumber_t agcount)
-{
-       xfs_agnumber_t  index;
-       xfs_perag_t     *pag;
-       xfs_sb_t        *sbp = &mp->m_sb;
-       uint64_t        ifree = 0;
-       uint64_t        ialloc = 0;
-       uint64_t        bfree = 0;
-       uint64_t        bfreelst = 0;
-       uint64_t        btree = 0;
-       int             error;
-
-       for (index = 0; index < agcount; index++) {
-               /*
-                * read the agf, then the agi. This gets us
-                * all the information we need and populates the
-                * per-ag structures for us.
-                */
-               error = xfs_alloc_pagf_init(mp, NULL, index, 0);
-               if (error)
-                       return error;
-
-               error = xfs_ialloc_pagi_init(mp, NULL, index);
-               if (error)
-                       return error;
-               pag = xfs_perag_get(mp, index);
-               ifree += pag->pagi_freecount;
-               ialloc += pag->pagi_count;
-               bfree += pag->pagf_freeblks;
-               bfreelst += pag->pagf_flcount;
-               btree += pag->pagf_btreeblks;
-               xfs_perag_put(pag);
-       }
-       /*
-        * Overwrite incore superblock counters with just-read data
-        */
-       spin_lock(&mp->m_sb_lock);
-       sbp->sb_ifree = ifree;
-       sbp->sb_icount = ialloc;
-       sbp->sb_fdblocks = bfree + bfreelst + btree;
-       spin_unlock(&mp->m_sb_lock);
-
-       /* Fixup the per-cpu counters as well. */
-       xfs_icsb_reinit_counters(mp);
-
-       return 0;
-}
-
-/*
- * Update alignment values based on mount options and sb values
- */
-STATIC int
-xfs_update_alignment(xfs_mount_t *mp)
-{
-       xfs_sb_t        *sbp = &(mp->m_sb);
-
-       if (mp->m_dalign) {
-               /*
-                * If stripe unit and stripe width are not multiples
-                * of the fs blocksize turn off alignment.
-                */
-               if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
-                   (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
-                       if (mp->m_flags & XFS_MOUNT_RETERR) {
-                               xfs_warn(mp, "alignment check failed: "
-                                        "(sunit/swidth vs. blocksize)");
-                               return XFS_ERROR(EINVAL);
-                       }
-                       mp->m_dalign = mp->m_swidth = 0;
-               } else {
-                       /*
-                        * Convert the stripe unit and width to FSBs.
-                        */
-                       mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
-                       if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
-                               if (mp->m_flags & XFS_MOUNT_RETERR) {
-                                       xfs_warn(mp, "alignment check failed: "
-                                                "(sunit/swidth vs. ag size)");
-                                       return XFS_ERROR(EINVAL);
-                               }
-                               xfs_warn(mp,
-               "stripe alignment turned off: sunit(%d)/swidth(%d) "
-               "incompatible with agsize(%d)",
-                                       mp->m_dalign, mp->m_swidth,
-                                       sbp->sb_agblocks);
-
-                               mp->m_dalign = 0;
-                               mp->m_swidth = 0;
-                       } else if (mp->m_dalign) {
-                               mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
-                       } else {
-                               if (mp->m_flags & XFS_MOUNT_RETERR) {
-                                       xfs_warn(mp, "alignment check failed: "
-                                               "sunit(%d) less than bsize(%d)",
-                                               mp->m_dalign,
-                                               mp->m_blockmask +1);
-                                       return XFS_ERROR(EINVAL);
-                               }
-                               mp->m_swidth = 0;
-                       }
-               }
-
-               /*
-                * Update superblock with new values
-                * and log changes
-                */
-               if (xfs_sb_version_hasdalign(sbp)) {
-                       if (sbp->sb_unit != mp->m_dalign) {
-                               sbp->sb_unit = mp->m_dalign;
-                               mp->m_update_flags |= XFS_SB_UNIT;
-                       }
-                       if (sbp->sb_width != mp->m_swidth) {
-                               sbp->sb_width = mp->m_swidth;
-                               mp->m_update_flags |= XFS_SB_WIDTH;
-                       }
-               }
-       } else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
-                   xfs_sb_version_hasdalign(&mp->m_sb)) {
-                       mp->m_dalign = sbp->sb_unit;
-                       mp->m_swidth = sbp->sb_width;
-       }
-
-       return 0;
-}
-
 /*
  * Set the maximum inode count for this filesystem
  */
@@ -1277,7 +659,7 @@ xfs_mountfs(
        uint            quotaflags = 0;
        int             error = 0;
 
-       xfs_mount_common(mp, sbp);
+       xfs_sb_mount_common(mp, sbp);
 
        /*
         * Check for a mismatched features2 values.  Older kernels
@@ -1714,48 +1096,6 @@ xfs_log_sbcount(xfs_mount_t *mp)
 }
 
 /*
- * xfs_mod_sb() can be used to copy arbitrary changes to the
- * in-core superblock into the superblock buffer to be logged.
- * It does not provide the higher level of locking that is
- * needed to protect the in-core superblock from concurrent
- * access.
- */
-void
-xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
-{
-       xfs_buf_t       *bp;
-       int             first;
-       int             last;
-       xfs_mount_t     *mp;
-       xfs_sb_field_t  f;
-
-       ASSERT(fields);
-       if (!fields)
-               return;
-       mp = tp->t_mountp;
-       bp = xfs_trans_getsb(tp, mp, 0);
-       first = sizeof(xfs_sb_t);
-       last = 0;
-
-       /* translate/copy */
-
-       xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, fields);
-
-       /* find modified range */
-       f = (xfs_sb_field_t)xfs_highbit64((__uint64_t)fields);
-       ASSERT((1LL << f) & XFS_SB_MOD_BITS);
-       last = xfs_sb_info[f + 1].offset - 1;
-
-       f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
-       ASSERT((1LL << f) & XFS_SB_MOD_BITS);
-       first = xfs_sb_info[f].offset;
-
-       xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SB_BUF);
-       xfs_trans_log_buf(tp, bp, first, last);
-}
-
-
-/*
  * xfs_mod_incore_sb_unlocked() is a utility routine common used to apply
  * a delta to a specified field in the in-core superblock.  Simply
  * switch on the field indicated and apply the delta to that field.
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index b004cec..10761c3 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -334,14 +334,6 @@ xfs_daddr_to_agbno(struct xfs_mount *mp, xfs_daddr_t d)
 }
 
 /*
- * perag get/put wrappers for ref counting
- */
-struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
-struct xfs_perag *xfs_perag_get_tag(struct xfs_mount *mp, xfs_agnumber_t agno,
-                                       int tag);
-void   xfs_perag_put(struct xfs_perag *pag);
-
-/*
  * Per-cpu superblock locking functions
  */
 #ifdef HAVE_PERCPU_SB
@@ -373,6 +365,8 @@ typedef struct xfs_mod_sb {
 extern int     xfs_log_sbcount(xfs_mount_t *);
 extern __uint64_t xfs_default_resblks(xfs_mount_t *mp);
 extern int     xfs_mountfs(xfs_mount_t *mp);
+extern int     xfs_initialize_perag(xfs_mount_t *mp, xfs_agnumber_t agcount,
+                                    xfs_agnumber_t *maxagi);
 
 extern void    xfs_unmountfs(xfs_mount_t *);
 extern int     xfs_mod_incore_sb(xfs_mount_t *, xfs_sb_field_t, int64_t, int);
@@ -391,13 +385,4 @@ extern void        xfs_set_low_space_thresholds(struct 
xfs_mount *);
 
 #endif /* __KERNEL__ */
 
-extern void    xfs_sb_calc_crc(struct xfs_buf  *);
-extern void    xfs_mod_sb(struct xfs_trans *, __int64_t);
-extern int     xfs_initialize_perag(struct xfs_mount *, xfs_agnumber_t,
-                                       xfs_agnumber_t *);
-extern void    xfs_sb_from_disk(struct xfs_sb *, struct xfs_dsb *);
-extern void    xfs_sb_to_disk(struct xfs_dsb *, struct xfs_sb *, __int64_t);
-
-extern const struct xfs_buf_ops xfs_sb_buf_ops;
-
 #endif /* __XFS_MOUNT_H__ */
diff --git a/fs/xfs/xfs_sb.c b/fs/xfs/xfs_sb.c
new file mode 100644
index 0000000..2a7e87a
--- /dev/null
+++ b/fs/xfs/xfs_sb.c
@@ -0,0 +1,716 @@
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_types.h"
+#include "xfs_bit.h"
+#include "xfs_log.h"
+#include "xfs_inum.h"
+#include "xfs_trans.h"
+#include "xfs_trans_priv.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_mount.h"
+#include "xfs_da_btree.h"
+#include "xfs_dir2_format.h"
+#include "xfs_dir2.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_dinode.h"
+#include "xfs_inode.h"
+#include "xfs_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_alloc.h"
+#include "xfs_rtalloc.h"
+#include "xfs_bmap.h"
+#include "xfs_error.h"
+#include "xfs_quota.h"
+#include "xfs_fsops.h"
+#include "xfs_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_buf_item.h"
+
+/*
+ * Physical superblock buffer manipulations. Shared with libxfs in userspace.
+ */
+
+static const struct {
+       short offset;
+       short type;     /* 0 = integer
+                        * 1 = binary / string (no translation)
+                        */
+} xfs_sb_info[] = {
+    { offsetof(xfs_sb_t, sb_magicnum),   0 },
+    { offsetof(xfs_sb_t, sb_blocksize),  0 },
+    { offsetof(xfs_sb_t, sb_dblocks),    0 },
+    { offsetof(xfs_sb_t, sb_rblocks),    0 },
+    { offsetof(xfs_sb_t, sb_rextents),   0 },
+    { offsetof(xfs_sb_t, sb_uuid),       1 },
+    { offsetof(xfs_sb_t, sb_logstart),   0 },
+    { offsetof(xfs_sb_t, sb_rootino),    0 },
+    { offsetof(xfs_sb_t, sb_rbmino),     0 },
+    { offsetof(xfs_sb_t, sb_rsumino),    0 },
+    { offsetof(xfs_sb_t, sb_rextsize),   0 },
+    { offsetof(xfs_sb_t, sb_agblocks),   0 },
+    { offsetof(xfs_sb_t, sb_agcount),    0 },
+    { offsetof(xfs_sb_t, sb_rbmblocks),  0 },
+    { offsetof(xfs_sb_t, sb_logblocks),  0 },
+    { offsetof(xfs_sb_t, sb_versionnum), 0 },
+    { offsetof(xfs_sb_t, sb_sectsize),   0 },
+    { offsetof(xfs_sb_t, sb_inodesize),  0 },
+    { offsetof(xfs_sb_t, sb_inopblock),  0 },
+    { offsetof(xfs_sb_t, sb_fname[0]),   1 },
+    { offsetof(xfs_sb_t, sb_blocklog),   0 },
+    { offsetof(xfs_sb_t, sb_sectlog),    0 },
+    { offsetof(xfs_sb_t, sb_inodelog),   0 },
+    { offsetof(xfs_sb_t, sb_inopblog),   0 },
+    { offsetof(xfs_sb_t, sb_agblklog),   0 },
+    { offsetof(xfs_sb_t, sb_rextslog),   0 },
+    { offsetof(xfs_sb_t, sb_inprogress), 0 },
+    { offsetof(xfs_sb_t, sb_imax_pct),   0 },
+    { offsetof(xfs_sb_t, sb_icount),     0 },
+    { offsetof(xfs_sb_t, sb_ifree),      0 },
+    { offsetof(xfs_sb_t, sb_fdblocks),   0 },
+    { offsetof(xfs_sb_t, sb_frextents),  0 },
+    { offsetof(xfs_sb_t, sb_uquotino),   0 },
+    { offsetof(xfs_sb_t, sb_gquotino),   0 },
+    { offsetof(xfs_sb_t, sb_qflags),     0 },
+    { offsetof(xfs_sb_t, sb_flags),      0 },
+    { offsetof(xfs_sb_t, sb_shared_vn),  0 },
+    { offsetof(xfs_sb_t, sb_inoalignmt), 0 },
+    { offsetof(xfs_sb_t, sb_unit),      0 },
+    { offsetof(xfs_sb_t, sb_width),     0 },
+    { offsetof(xfs_sb_t, sb_dirblklog),         0 },
+    { offsetof(xfs_sb_t, sb_logsectlog), 0 },
+    { 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 },
+    { offsetof(xfs_sb_t, sb_features_compat), 0 },
+    { offsetof(xfs_sb_t, sb_features_ro_compat), 0 },
+    { offsetof(xfs_sb_t, sb_features_incompat), 0 },
+    { offsetof(xfs_sb_t, sb_features_log_incompat), 0 },
+    { offsetof(xfs_sb_t, sb_crc),       0 },
+    { offsetof(xfs_sb_t, sb_pad),       0 },
+    { offsetof(xfs_sb_t, sb_pquotino),  0 },
+    { offsetof(xfs_sb_t, sb_lsn),       0 },
+    { sizeof(xfs_sb_t),                         0 }
+};
+
+/*
+ * Reference counting access wrappers to the perag structures.
+ * Because we never free per-ag structures, the only thing we
+ * have to protect against changes is the tree structure itself.
+ */
+struct xfs_perag *
+xfs_perag_get(
+       struct xfs_mount        *mp,
+       xfs_agnumber_t          agno)
+{
+       struct xfs_perag        *pag;
+       int                     ref = 0;
+
+       rcu_read_lock();
+       pag = radix_tree_lookup(&mp->m_perag_tree, agno);
+       if (pag) {
+               ASSERT(atomic_read(&pag->pag_ref) >= 0);
+               ref = atomic_inc_return(&pag->pag_ref);
+       }
+       rcu_read_unlock();
+       trace_xfs_perag_get(mp, agno, ref, _RET_IP_);
+       return pag;
+}
+
+/*
+ * search from @first to find the next perag with the given tag set.
+ */
+struct xfs_perag *
+xfs_perag_get_tag(
+       struct xfs_mount        *mp,
+       xfs_agnumber_t          first,
+       int                     tag)
+{
+       struct xfs_perag        *pag;
+       int                     found;
+       int                     ref;
+
+       rcu_read_lock();
+       found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
+                                       (void **)&pag, first, 1, tag);
+       if (found <= 0) {
+               rcu_read_unlock();
+               return NULL;
+       }
+       ref = atomic_inc_return(&pag->pag_ref);
+       rcu_read_unlock();
+       trace_xfs_perag_get_tag(mp, pag->pag_agno, ref, _RET_IP_);
+       return pag;
+}
+
+void
+xfs_perag_put(
+       struct xfs_perag        *pag)
+{
+       int     ref;
+
+       ASSERT(atomic_read(&pag->pag_ref) > 0);
+       ref = atomic_dec_return(&pag->pag_ref);
+       trace_xfs_perag_put(pag->pag_mount, pag->pag_agno, ref, _RET_IP_);
+}
+
+/*
+ * Check the validity of the SB found.
+ */
+STATIC int
+xfs_mount_validate_sb(
+       xfs_mount_t     *mp,
+       xfs_sb_t        *sbp,
+       bool            check_inprogress,
+       bool            check_version)
+{
+
+       /*
+        * If the log device and data device have the
+        * same device number, the log is internal.
+        * Consequently, the sb_logstart should be non-zero.  If
+        * we have a zero sb_logstart in this case, we may be trying to mount
+        * a volume filesystem in a non-volume manner.
+        */
+       if (sbp->sb_magicnum != XFS_SB_MAGIC) {
+               xfs_warn(mp, "bad magic number");
+               return XFS_ERROR(EWRONGFS);
+       }
+
+
+       if (!xfs_sb_good_version(sbp)) {
+               xfs_warn(mp, "bad version");
+               return XFS_ERROR(EWRONGFS);
+       }
+
+       /*
+        * Version 5 superblock feature mask validation. Reject combinations the
+        * kernel cannot support up front before checking anything else. For
+        * write validation, we don't need to check feature masks.
+        */
+       if (check_version && XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) {
+               xfs_alert(mp,
+"Version 5 superblock detected. This kernel has EXPERIMENTAL support 
enabled!\n"
+"Use of these features in this kernel is at your own risk!");
+
+               if (xfs_sb_has_compat_feature(sbp,
+                                       XFS_SB_FEAT_COMPAT_UNKNOWN)) {
+                       xfs_warn(mp,
+"Superblock has unknown compatible features (0x%x) enabled.\n"
+"Using a more recent kernel is recommended.",
+                               (sbp->sb_features_compat &
+                                               XFS_SB_FEAT_COMPAT_UNKNOWN));
+               }
+
+               if (xfs_sb_has_ro_compat_feature(sbp,
+                                       XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
+                       xfs_alert(mp,
+"Superblock has unknown read-only compatible features (0x%x) enabled.",
+                               (sbp->sb_features_ro_compat &
+                                               XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
+                       if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
+                               xfs_warn(mp,
+"Attempted to mount read-only compatible filesystem read-write.\n"
+"Filesystem can only be safely mounted read only.");
+                               return XFS_ERROR(EINVAL);
+                       }
+               }
+               if (xfs_sb_has_incompat_feature(sbp,
+                                       XFS_SB_FEAT_INCOMPAT_UNKNOWN)) {
+                       xfs_warn(mp,
+"Superblock has unknown incompatible features (0x%x) enabled.\n"
+"Filesystem can not be safely mounted by this kernel.",
+                               (sbp->sb_features_incompat &
+                                               XFS_SB_FEAT_INCOMPAT_UNKNOWN));
+                       return XFS_ERROR(EINVAL);
+               }
+       }
+
+       if (unlikely(
+           sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {
+               xfs_warn(mp,
+               "filesystem is marked as having an external log; "
+               "specify logdev on the mount command line.");
+               return XFS_ERROR(EINVAL);
+       }
+
+       if (unlikely(
+           sbp->sb_logstart != 0 && mp->m_logdev_targp != mp->m_ddev_targp)) {
+               xfs_warn(mp,
+               "filesystem is marked as having an internal log; "
+               "do not specify logdev on the mount command line.");
+               return XFS_ERROR(EINVAL);
+       }
+
+       /*
+        * More sanity checking.  Most of these were stolen directly from
+        * xfs_repair.
+        */
+       if (unlikely(
+           sbp->sb_agcount <= 0                                        ||
+           sbp->sb_sectsize < XFS_MIN_SECTORSIZE                       ||
+           sbp->sb_sectsize > XFS_MAX_SECTORSIZE                       ||
+           sbp->sb_sectlog < XFS_MIN_SECTORSIZE_LOG                    ||
+           sbp->sb_sectlog > XFS_MAX_SECTORSIZE_LOG                    ||
+           sbp->sb_sectsize != (1 << sbp->sb_sectlog)                  ||
+           sbp->sb_blocksize < XFS_MIN_BLOCKSIZE                       ||
+           sbp->sb_blocksize > XFS_MAX_BLOCKSIZE                       ||
+           sbp->sb_blocklog < XFS_MIN_BLOCKSIZE_LOG                    ||
+           sbp->sb_blocklog > XFS_MAX_BLOCKSIZE_LOG                    ||
+           sbp->sb_blocksize != (1 << sbp->sb_blocklog)                ||
+           sbp->sb_inodesize < XFS_DINODE_MIN_SIZE                     ||
+           sbp->sb_inodesize > XFS_DINODE_MAX_SIZE                     ||
+           sbp->sb_inodelog < XFS_DINODE_MIN_LOG                       ||
+           sbp->sb_inodelog > XFS_DINODE_MAX_LOG                       ||
+           sbp->sb_inodesize != (1 << sbp->sb_inodelog)                ||
+           (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog)   ||
+           (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE)  ||
+           (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE)  ||
+           (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))) {
+               XFS_CORRUPTION_ERROR("SB sanity check failed",
+                               XFS_ERRLEVEL_LOW, mp, sbp);
+               return XFS_ERROR(EFSCORRUPTED);
+       }
+
+       /*
+        * Until this is fixed only page-sized or smaller data blocks work.
+        */
+       if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {
+               xfs_warn(mp,
+               "File system with blocksize %d bytes. "
+               "Only pagesize (%ld) or less will currently work.",
+                               sbp->sb_blocksize, PAGE_SIZE);
+               return XFS_ERROR(ENOSYS);
+       }
+
+       /*
+        * Currently only very few inode sizes are supported.
+        */
+       switch (sbp->sb_inodesize) {
+       case 256:
+       case 512:
+       case 1024:
+       case 2048:
+               break;
+       default:
+               xfs_warn(mp, "inode size of %d bytes not supported",
+                               sbp->sb_inodesize);
+               return XFS_ERROR(ENOSYS);
+       }
+
+       if (xfs_sb_validate_fsb_count(sbp, sbp->sb_dblocks) ||
+           xfs_sb_validate_fsb_count(sbp, sbp->sb_rblocks)) {
+               xfs_warn(mp,
+               "file system too large to be mounted on this system.");
+               return XFS_ERROR(EFBIG);
+       }
+
+       if (check_inprogress && sbp->sb_inprogress) {
+               xfs_warn(mp, "Offline file system operation in progress!");
+               return XFS_ERROR(EFSCORRUPTED);
+       }
+
+       /*
+        * Version 1 directory format has never worked on Linux.
+        */
+       if (unlikely(!xfs_sb_version_hasdirv2(sbp))) {
+               xfs_warn(mp, "file system using version 1 directory format");
+               return XFS_ERROR(ENOSYS);
+       }
+
+       return 0;
+}
+
+void
+xfs_sb_from_disk(
+       struct xfs_sb   *to,
+       xfs_dsb_t       *from)
+{
+       to->sb_magicnum = be32_to_cpu(from->sb_magicnum);
+       to->sb_blocksize = be32_to_cpu(from->sb_blocksize);
+       to->sb_dblocks = be64_to_cpu(from->sb_dblocks);
+       to->sb_rblocks = be64_to_cpu(from->sb_rblocks);
+       to->sb_rextents = be64_to_cpu(from->sb_rextents);
+       memcpy(&to->sb_uuid, &from->sb_uuid, sizeof(to->sb_uuid));
+       to->sb_logstart = be64_to_cpu(from->sb_logstart);
+       to->sb_rootino = be64_to_cpu(from->sb_rootino);
+       to->sb_rbmino = be64_to_cpu(from->sb_rbmino);
+       to->sb_rsumino = be64_to_cpu(from->sb_rsumino);
+       to->sb_rextsize = be32_to_cpu(from->sb_rextsize);
+       to->sb_agblocks = be32_to_cpu(from->sb_agblocks);
+       to->sb_agcount = be32_to_cpu(from->sb_agcount);
+       to->sb_rbmblocks = be32_to_cpu(from->sb_rbmblocks);
+       to->sb_logblocks = be32_to_cpu(from->sb_logblocks);
+       to->sb_versionnum = be16_to_cpu(from->sb_versionnum);
+       to->sb_sectsize = be16_to_cpu(from->sb_sectsize);
+       to->sb_inodesize = be16_to_cpu(from->sb_inodesize);
+       to->sb_inopblock = be16_to_cpu(from->sb_inopblock);
+       memcpy(&to->sb_fname, &from->sb_fname, sizeof(to->sb_fname));
+       to->sb_blocklog = from->sb_blocklog;
+       to->sb_sectlog = from->sb_sectlog;
+       to->sb_inodelog = from->sb_inodelog;
+       to->sb_inopblog = from->sb_inopblog;
+       to->sb_agblklog = from->sb_agblklog;
+       to->sb_rextslog = from->sb_rextslog;
+       to->sb_inprogress = from->sb_inprogress;
+       to->sb_imax_pct = from->sb_imax_pct;
+       to->sb_icount = be64_to_cpu(from->sb_icount);
+       to->sb_ifree = be64_to_cpu(from->sb_ifree);
+       to->sb_fdblocks = be64_to_cpu(from->sb_fdblocks);
+       to->sb_frextents = be64_to_cpu(from->sb_frextents);
+       to->sb_uquotino = be64_to_cpu(from->sb_uquotino);
+       to->sb_gquotino = be64_to_cpu(from->sb_gquotino);
+       to->sb_qflags = be16_to_cpu(from->sb_qflags);
+       to->sb_flags = from->sb_flags;
+       to->sb_shared_vn = from->sb_shared_vn;
+       to->sb_inoalignmt = be32_to_cpu(from->sb_inoalignmt);
+       to->sb_unit = be32_to_cpu(from->sb_unit);
+       to->sb_width = be32_to_cpu(from->sb_width);
+       to->sb_dirblklog = from->sb_dirblklog;
+       to->sb_logsectlog = from->sb_logsectlog;
+       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);
+       to->sb_features_compat = be32_to_cpu(from->sb_features_compat);
+       to->sb_features_ro_compat = be32_to_cpu(from->sb_features_ro_compat);
+       to->sb_features_incompat = be32_to_cpu(from->sb_features_incompat);
+       to->sb_features_log_incompat =
+                               be32_to_cpu(from->sb_features_log_incompat);
+       to->sb_pad = 0;
+       to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
+       to->sb_lsn = be64_to_cpu(from->sb_lsn);
+}
+
+/*
+ * Copy in core superblock to ondisk one.
+ *
+ * The fields argument is mask of superblock fields to copy.
+ */
+void
+xfs_sb_to_disk(
+       xfs_dsb_t       *to,
+       xfs_sb_t        *from,
+       __int64_t       fields)
+{
+       xfs_caddr_t     to_ptr = (xfs_caddr_t)to;
+       xfs_caddr_t     from_ptr = (xfs_caddr_t)from;
+       xfs_sb_field_t  f;
+       int             first;
+       int             size;
+
+       ASSERT(fields);
+       if (!fields)
+               return;
+
+       while (fields) {
+               f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
+               first = xfs_sb_info[f].offset;
+               size = xfs_sb_info[f + 1].offset - first;
+
+               ASSERT(xfs_sb_info[f].type == 0 || xfs_sb_info[f].type == 1);
+
+               if (size == 1 || xfs_sb_info[f].type == 1) {
+                       memcpy(to_ptr + first, from_ptr + first, size);
+               } else {
+                       switch (size) {
+                       case 2:
+                               *(__be16 *)(to_ptr + first) =
+                                       cpu_to_be16(*(__u16 *)(from_ptr + 
first));
+                               break;
+                       case 4:
+                               *(__be32 *)(to_ptr + first) =
+                                       cpu_to_be32(*(__u32 *)(from_ptr + 
first));
+                               break;
+                       case 8:
+                               *(__be64 *)(to_ptr + first) =
+                                       cpu_to_be64(*(__u64 *)(from_ptr + 
first));
+                               break;
+                       default:
+                               ASSERT(0);
+                       }
+               }
+
+               fields &= ~(1LL << f);
+       }
+}
+
+static int
+xfs_sb_verify(
+       struct xfs_buf  *bp,
+       bool            check_version)
+{
+       struct xfs_mount *mp = bp->b_target->bt_mount;
+       struct xfs_sb   sb;
+
+       xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp));
+
+       /*
+        * Only check the in progress field for the primary superblock as
+        * mkfs.xfs doesn't clear it from secondary superblocks.
+        */
+       return xfs_mount_validate_sb(mp, &sb, bp->b_bn == XFS_SB_DADDR,
+                                    check_version);
+}
+
+/*
+ * If the superblock has the CRC feature bit set or the CRC field is non-null,
+ * check that the CRC is valid.  We check the CRC field is non-null because a
+ * single bit error could clear the feature bit and unused parts of the
+ * superblock are supposed to be zero. Hence a non-null crc field indicates 
that
+ * we've potentially lost a feature bit and we should check it anyway.
+ */
+static void
+xfs_sb_read_verify(
+       struct xfs_buf  *bp)
+{
+       struct xfs_mount *mp = bp->b_target->bt_mount;
+       struct xfs_dsb  *dsb = XFS_BUF_TO_SBP(bp);
+       int             error;
+
+       /*
+        * open code the version check to avoid needing to convert the entire
+        * superblock from disk order just to check the version number
+        */
+       if (dsb->sb_magicnum == cpu_to_be32(XFS_SB_MAGIC) &&
+           (((be16_to_cpu(dsb->sb_versionnum) & XFS_SB_VERSION_NUMBITS) ==
+                                               XFS_SB_VERSION_5) ||
+            dsb->sb_crc != 0)) {
+
+               if (!xfs_verify_cksum(bp->b_addr, be16_to_cpu(dsb->sb_sectsize),
+                                     offsetof(struct xfs_sb, sb_crc))) {
+                       error = EFSCORRUPTED;
+                       goto out_error;
+               }
+       }
+       error = xfs_sb_verify(bp, true);
+
+out_error:
+       if (error) {
+               XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, 
bp->b_addr);
+               xfs_buf_ioerror(bp, error);
+       }
+}
+
+/*
+ * We may be probed for a filesystem match, so we may not want to emit
+ * messages when the superblock buffer is not actually an XFS superblock.
+ * If we find an XFS superblock, the run a normal, noisy mount because we are
+ * really going to mount it and want to know about errors.
+ */
+static void
+xfs_sb_quiet_read_verify(
+       struct xfs_buf  *bp)
+{
+       struct xfs_dsb  *dsb = XFS_BUF_TO_SBP(bp);
+
+
+       if (dsb->sb_magicnum == cpu_to_be32(XFS_SB_MAGIC)) {
+               /* XFS filesystem, verify noisily! */
+               xfs_sb_read_verify(bp);
+               return;
+       }
+       /* quietly fail */
+       xfs_buf_ioerror(bp, EWRONGFS);
+}
+
+static void
+xfs_sb_write_verify(
+       struct xfs_buf          *bp)
+{
+       struct xfs_mount        *mp = bp->b_target->bt_mount;
+       struct xfs_buf_log_item *bip = bp->b_fspriv;
+       int                     error;
+
+       error = xfs_sb_verify(bp, false);
+       if (error) {
+               XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, 
bp->b_addr);
+               xfs_buf_ioerror(bp, error);
+               return;
+       }
+
+       if (!xfs_sb_version_hascrc(&mp->m_sb))
+               return;
+
+       if (bip)
+               XFS_BUF_TO_SBP(bp)->sb_lsn = cpu_to_be64(bip->bli_item.li_lsn);
+
+       xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
+                        offsetof(struct xfs_sb, sb_crc));
+}
+
+const struct xfs_buf_ops xfs_sb_buf_ops = {
+       .verify_read = xfs_sb_read_verify,
+       .verify_write = xfs_sb_write_verify,
+};
+
+const struct xfs_buf_ops xfs_sb_quiet_buf_ops = {
+       .verify_read = xfs_sb_quiet_read_verify,
+       .verify_write = xfs_sb_write_verify,
+};
+
+/*
+ * xfs_mount_common
+ *
+ * Mount initialization code establishing various mount
+ * fields from the superblock associated with the given
+ * mount structure
+ */
+void
+xfs_sb_mount_common(
+       struct xfs_mount *mp,
+       struct xfs_sb   *sbp)
+{
+       mp->m_agfrotor = mp->m_agirotor = 0;
+       spin_lock_init(&mp->m_agirotor_lock);
+       mp->m_maxagi = mp->m_sb.sb_agcount;
+       mp->m_blkbit_log = sbp->sb_blocklog + XFS_NBBYLOG;
+       mp->m_blkbb_log = sbp->sb_blocklog - BBSHIFT;
+       mp->m_sectbb_log = sbp->sb_sectlog - BBSHIFT;
+       mp->m_agno_log = xfs_highbit32(sbp->sb_agcount - 1) + 1;
+       mp->m_agino_log = sbp->sb_inopblog + sbp->sb_agblklog;
+       mp->m_blockmask = sbp->sb_blocksize - 1;
+       mp->m_blockwsize = sbp->sb_blocksize >> XFS_WORDLOG;
+       mp->m_blockwmask = mp->m_blockwsize - 1;
+
+       mp->m_alloc_mxr[0] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 1);
+       mp->m_alloc_mxr[1] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 0);
+       mp->m_alloc_mnr[0] = mp->m_alloc_mxr[0] / 2;
+       mp->m_alloc_mnr[1] = mp->m_alloc_mxr[1] / 2;
+
+       mp->m_inobt_mxr[0] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 1);
+       mp->m_inobt_mxr[1] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 0);
+       mp->m_inobt_mnr[0] = mp->m_inobt_mxr[0] / 2;
+       mp->m_inobt_mnr[1] = mp->m_inobt_mxr[1] / 2;
+
+       mp->m_bmap_dmxr[0] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 1);
+       mp->m_bmap_dmxr[1] = xfs_bmbt_maxrecs(mp, sbp->sb_blocksize, 0);
+       mp->m_bmap_dmnr[0] = mp->m_bmap_dmxr[0] / 2;
+       mp->m_bmap_dmnr[1] = mp->m_bmap_dmxr[1] / 2;
+
+       mp->m_bsize = XFS_FSB_TO_BB(mp, 1);
+       mp->m_ialloc_inos = (int)MAX((__uint16_t)XFS_INODES_PER_CHUNK,
+                                       sbp->sb_inopblock);
+       mp->m_ialloc_blks = mp->m_ialloc_inos >> sbp->sb_inopblog;
+}
+
+/*
+ * xfs_initialize_perag_data
+ *
+ * Read in each per-ag structure so we can count up the number of
+ * allocated inodes, free inodes and used filesystem blocks as this
+ * information is no longer persistent in the superblock. Once we have
+ * this information, write it into the in-core superblock structure.
+ */
+int
+xfs_initialize_perag_data(xfs_mount_t *mp, xfs_agnumber_t agcount)
+{
+       xfs_agnumber_t  index;
+       xfs_perag_t     *pag;
+       xfs_sb_t        *sbp = &mp->m_sb;
+       uint64_t        ifree = 0;
+       uint64_t        ialloc = 0;
+       uint64_t        bfree = 0;
+       uint64_t        bfreelst = 0;
+       uint64_t        btree = 0;
+       int             error;
+
+       for (index = 0; index < agcount; index++) {
+               /*
+                * read the agf, then the agi. This gets us
+                * all the information we need and populates the
+                * per-ag structures for us.
+                */
+               error = xfs_alloc_pagf_init(mp, NULL, index, 0);
+               if (error)
+                       return error;
+
+               error = xfs_ialloc_pagi_init(mp, NULL, index);
+               if (error)
+                       return error;
+               pag = xfs_perag_get(mp, index);
+               ifree += pag->pagi_freecount;
+               ialloc += pag->pagi_count;
+               bfree += pag->pagf_freeblks;
+               bfreelst += pag->pagf_flcount;
+               btree += pag->pagf_btreeblks;
+               xfs_perag_put(pag);
+       }
+       /*
+        * Overwrite incore superblock counters with just-read data
+        */
+       spin_lock(&mp->m_sb_lock);
+       sbp->sb_ifree = ifree;
+       sbp->sb_icount = ialloc;
+       sbp->sb_fdblocks = bfree + bfreelst + btree;
+       spin_unlock(&mp->m_sb_lock);
+
+       /* Fixup the per-cpu counters as well. */
+       xfs_icsb_reinit_counters(mp);
+
+       return 0;
+}
+
+/*
+ * xfs_mod_sb() can be used to copy arbitrary changes to the
+ * in-core superblock into the superblock buffer to be logged.
+ * It does not provide the higher level of locking that is
+ * needed to protect the in-core superblock from concurrent
+ * access.
+ */
+void
+xfs_mod_sb(xfs_trans_t *tp, __int64_t fields)
+{
+       xfs_buf_t       *bp;
+       int             first;
+       int             last;
+       xfs_mount_t     *mp;
+       xfs_sb_field_t  f;
+
+       ASSERT(fields);
+       if (!fields)
+               return;
+       mp = tp->t_mountp;
+       bp = xfs_trans_getsb(tp, mp, 0);
+       first = sizeof(xfs_sb_t);
+       last = 0;
+
+       /* translate/copy */
+
+       xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, fields);
+
+       /* find modified range */
+       f = (xfs_sb_field_t)xfs_highbit64((__uint64_t)fields);
+       ASSERT((1LL << f) & XFS_SB_MOD_BITS);
+       last = xfs_sb_info[f + 1].offset - 1;
+
+       f = (xfs_sb_field_t)xfs_lowbit64((__uint64_t)fields);
+       ASSERT((1LL << f) & XFS_SB_MOD_BITS);
+       first = xfs_sb_info[f].offset;
+
+       xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SB_BUF);
+       xfs_trans_log_buf(tp, bp, first, last);
+}
diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index 2de58a8..25d19d0 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -26,6 +26,7 @@
 
 struct xfs_buf;
 struct xfs_mount;
+struct xfs_trans;
 
 #define        XFS_SB_MAGIC            0x58465342      /* 'XFSB' */
 #define        XFS_SB_VERSION_1        1               /* 5.3, 6.0.1, 6.1 */
@@ -654,4 +655,22 @@ xfs_sb_has_incompat_log_feature(
 #define XFS_B_TO_FSBT(mp,b)    (((__uint64_t)(b)) >> (mp)->m_sb.sb_blocklog)
 #define XFS_B_FSB_OFFSET(mp,b) ((b) & (mp)->m_blockmask)
 
+/*
+ * perag get/put wrappers for ref counting
+ */
+extern struct xfs_perag *xfs_perag_get(struct xfs_mount *, xfs_agnumber_t);
+extern struct xfs_perag *xfs_perag_get_tag(struct xfs_mount *, xfs_agnumber_t,
+                                          int tag);
+extern void    xfs_perag_put(struct xfs_perag *pag);
+extern int     xfs_initialize_perag_data(struct xfs_mount *, xfs_agnumber_t);
+
+extern void    xfs_sb_calc_crc(struct xfs_buf  *);
+extern void    xfs_mod_sb(struct xfs_trans *, __int64_t);
+extern void    xfs_sb_mount_common(struct xfs_mount *, struct xfs_sb *);
+extern void    xfs_sb_from_disk(struct xfs_sb *, struct xfs_dsb *);
+extern void    xfs_sb_to_disk(struct xfs_dsb *, struct xfs_sb *, __int64_t);
+
+extern const struct xfs_buf_ops xfs_sb_buf_ops;
+extern const struct xfs_buf_ops xfs_sb_quiet_buf_ops;
+
 #endif /* __XFS_SB_H__ */
-- 
1.7.10.4

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