/*

   * 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_sb.h"
  #include "xfs_ag.h"

  #include "xfs_dir2.h"

  #include "xfs_mount.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_rw.h"
  #include "xfs_quota.h"
  #include "xfs_fsops.h"

  #include "xfs_utils.h"

  #include "xfs_trace.h"

  STATIC void	xfs_unmountfs_wait(xfs_mount_t *);

  
  #ifdef HAVE_PERCPU_SB

  STATIC void	xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t,

  						int);
  STATIC void	xfs_icsb_balance_counter_locked(xfs_mount_t *, xfs_sb_field_t,
  						int);

  STATIC void	xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);

  #else

  #define xfs_icsb_balance_counter(mp, a, b)		do { } while (0)
  #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 },

      { sizeof(xfs_sb_t),			 0 }
  };

  static DEFINE_MUTEX(xfs_uuid_table_mutex);
  static int xfs_uuid_table_size;
  static uuid_t *xfs_uuid_table;
  
  /*
   * See if the UUID is unique among mounted XFS filesystems.
   * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
   */
  STATIC int
  xfs_uuid_mount(
  	struct xfs_mount	*mp)
  {
  	uuid_t			*uuid = &mp->m_sb.sb_uuid;
  	int			hole, i;
  
  	if (mp->m_flags & XFS_MOUNT_NOUUID)
  		return 0;
  
  	if (uuid_is_nil(uuid)) {

  		xfs_warn(mp, "Filesystem has nil UUID - can't mount");

  		return XFS_ERROR(EINVAL);
  	}
  
  	mutex_lock(&xfs_uuid_table_mutex);
  	for (i = 0, hole = -1; i < xfs_uuid_table_size; i++) {
  		if (uuid_is_nil(&xfs_uuid_table[i])) {
  			hole = i;
  			continue;
  		}
  		if (uuid_equal(uuid, &xfs_uuid_table[i]))
  			goto out_duplicate;
  	}
  
  	if (hole < 0) {
  		xfs_uuid_table = kmem_realloc(xfs_uuid_table,
  			(xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
  			xfs_uuid_table_size  * sizeof(*xfs_uuid_table),
  			KM_SLEEP);
  		hole = xfs_uuid_table_size++;
  	}
  	xfs_uuid_table[hole] = *uuid;
  	mutex_unlock(&xfs_uuid_table_mutex);
  
  	return 0;
  
   out_duplicate:
  	mutex_unlock(&xfs_uuid_table_mutex);

  	xfs_warn(mp, "Filesystem has duplicate UUID - can't mount");

  	return XFS_ERROR(EINVAL);
  }
  
  STATIC void
  xfs_uuid_unmount(
  	struct xfs_mount	*mp)
  {
  	uuid_t			*uuid = &mp->m_sb.sb_uuid;
  	int			i;
  
  	if (mp->m_flags & XFS_MOUNT_NOUUID)
  		return;
  
  	mutex_lock(&xfs_uuid_table_mutex);
  	for (i = 0; i < xfs_uuid_table_size; i++) {
  		if (uuid_is_nil(&xfs_uuid_table[i]))
  			continue;
  		if (!uuid_equal(uuid, &xfs_uuid_table[i]))
  			continue;
  		memset(&xfs_uuid_table[i], 0, sizeof(uuid_t));
  		break;
  	}
  	ASSERT(i < xfs_uuid_table_size);
  	mutex_unlock(&xfs_uuid_table_mutex);
  }

  /*

   * 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)
  {
  	struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);
  
  	ASSERT(atomic_read(&pag->pag_ref) == 0);
  	kmem_free(pag);
  }

  /*

   * Free up the per-ag resources associated with the mount structure.

   */

  STATIC void

  xfs_free_perag(

  	xfs_mount_t	*mp)

  {

  	xfs_agnumber_t	agno;
  	struct xfs_perag *pag;
  
  	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
  		spin_lock(&mp->m_perag_lock);
  		pag = radix_tree_delete(&mp->m_perag_tree, agno);
  		spin_unlock(&mp->m_perag_lock);

  		ASSERT(pag);

  		ASSERT(atomic_read(&pag->pag_ref) == 0);

  		call_rcu(&pag->rcu_head, __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,
  	int		flags)

  {

  	int		loud = !(flags & XFS_MFSI_QUIET);

  	/*
  	 * 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) {

  		if (loud)
  			xfs_warn(mp, "bad magic number");

  		return XFS_ERROR(EWRONGFS);
  	}

  	if (!xfs_sb_good_version(sbp)) {

  		if (loud)
  			xfs_warn(mp, "bad version");

  		return XFS_ERROR(EWRONGFS);
  	}
  
  	if (unlikely(
  	    sbp->sb_logstart == 0 && mp->m_logdev_targp == mp->m_ddev_targp)) {

  		if (loud)
  			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)) {

  		if (loud)
  			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. 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 */))) {

  		if (loud)
  			xfs_warn(mp, "SB sanity check 1 failed");

  		return XFS_ERROR(EFSCORRUPTED);
  	}
  
  	/*
  	 * Sanity check AG count, size fields against data size field
  	 */
  	if (unlikely(
  	    sbp->sb_dblocks == 0 ||
  	    sbp->sb_dblocks >
  	     (xfs_drfsbno_t)sbp->sb_agcount * sbp->sb_agblocks ||
  	    sbp->sb_dblocks < (xfs_drfsbno_t)(sbp->sb_agcount - 1) *
  			      sbp->sb_agblocks + XFS_MIN_AG_BLOCKS)) {

  		if (loud)
  			xfs_warn(mp, "SB sanity check 2 failed");

  		return XFS_ERROR(EFSCORRUPTED);
  	}

  	/*
  	 * Until this is fixed only page-sized or smaller data blocks work.
  	 */
  	if (unlikely(sbp->sb_blocksize > PAGE_SIZE)) {

  		if (loud) {
  			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:

  		if (loud)
  			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)) {

  		if (loud)
  			xfs_warn(mp,
  		"file system too large to be mounted on this system.");

  		return XFS_ERROR(EFBIG);

  	}
  
  	if (unlikely(sbp->sb_inprogress)) {

  		if (loud)
  			xfs_warn(mp, "file system busy");

  		return XFS_ERROR(EFSCORRUPTED);
  	}
  
  	/*

  	 * Version 1 directory format has never worked on Linux.
  	 */

  	if (unlikely(!xfs_sb_version_hasdirv2(sbp))) {

  		if (loud)
  			xfs_warn(mp,
  				"file system using version 1 directory format");

  		return XFS_ERROR(ENOSYS);
  	}

  	return 0;
  }

  int

  xfs_initialize_perag(

  	xfs_mount_t	*mp,

  	xfs_agnumber_t	agcount,
  	xfs_agnumber_t	*maxagi)

  {
  	xfs_agnumber_t	index, max_metadata;

  	xfs_agnumber_t	first_initialised = 0;

  	xfs_perag_t	*pag;
  	xfs_agino_t	agino;
  	xfs_ino_t	ino;
  	xfs_sb_t	*sbp = &mp->m_sb;

  	int		error = -ENOMEM;

  	/*
  	 * Walk the current per-ag tree so we don't try to initialise AGs
  	 * that already exist (growfs case). Allocate and insert all the
  	 * AGs we don't find ready for initialisation.
  	 */
  	for (index = 0; index < agcount; index++) {
  		pag = xfs_perag_get(mp, index);
  		if (pag) {
  			xfs_perag_put(pag);
  			continue;
  		}

  		if (!first_initialised)
  			first_initialised = index;

  		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
  		if (!pag)

  			goto out_unwind;

  		pag->pag_agno = index;
  		pag->pag_mount = mp;

  		spin_lock_init(&pag->pag_ici_lock);

  		mutex_init(&pag->pag_ici_reclaim_lock);

  		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);

  		spin_lock_init(&pag->pag_buf_lock);
  		pag->pag_buf_tree = RB_ROOT;

  		if (radix_tree_preload(GFP_NOFS))

  			goto out_unwind;

  		spin_lock(&mp->m_perag_lock);
  		if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
  			BUG();
  			spin_unlock(&mp->m_perag_lock);

  			radix_tree_preload_end();
  			error = -EEXIST;
  			goto out_unwind;

  		}
  		spin_unlock(&mp->m_perag_lock);
  		radix_tree_preload_end();
  	}

  	/*
  	 * If we mount with the inode64 option, or no inode overflows
  	 * the legacy 32-bit address space clear the inode32 option.

  	 */

  	agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
  	ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
  
  	if ((mp->m_flags & XFS_MOUNT_SMALL_INUMS) && ino > XFS_MAXINUMBER_32)

  		mp->m_flags |= XFS_MOUNT_32BITINODES;

  	else

  		mp->m_flags &= ~XFS_MOUNT_32BITINODES;

  	if (mp->m_flags & XFS_MOUNT_32BITINODES) {

  		/*
  		 * Calculate how much should be reserved for inodes to meet
  		 * the max inode percentage.

  		 */
  		if (mp->m_maxicount) {
  			__uint64_t	icount;
  
  			icount = sbp->sb_dblocks * sbp->sb_imax_pct;
  			do_div(icount, 100);
  			icount += sbp->sb_agblocks - 1;

  			do_div(icount, sbp->sb_agblocks);

  			max_metadata = icount;
  		} else {
  			max_metadata = agcount;
  		}

  		for (index = 0; index < agcount; index++) {
  			ino = XFS_AGINO_TO_INO(mp, index, agino);

  			if (ino > XFS_MAXINUMBER_32) {

  				index++;
  				break;
  			}

  			pag = xfs_perag_get(mp, index);

  			pag->pagi_inodeok = 1;
  			if (index < max_metadata)
  				pag->pagf_metadata = 1;

  			xfs_perag_put(pag);

  		}
  	} else {

  		for (index = 0; index < agcount; index++) {

  			pag = xfs_perag_get(mp, index);

  			pag->pagi_inodeok = 1;

  			xfs_perag_put(pag);

  		}
  	}

  	if (maxagi)
  		*maxagi = index;
  	return 0;

  
  out_unwind:
  	kmem_free(pag);
  	for (; index > first_initialised; index--) {
  		pag = radix_tree_delete(&mp->m_perag_tree, index);
  		kmem_free(pag);
  	}
  	return error;

  }

  void
  xfs_sb_from_disk(
  	xfs_sb_t	*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);

  }

  /*

   * 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);
  	}
  }
  
  /*
   * xfs_readsb
   *
   * Does the initial read of the superblock.
   */
  int

  xfs_readsb(xfs_mount_t *mp, int flags)

  {
  	unsigned int	sector_size;

  	xfs_buf_t	*bp;

  	int		error;

  	int		loud = !(flags & XFS_MFSI_QUIET);

  
  	ASSERT(mp->m_sb_bp == NULL);
  	ASSERT(mp->m_ddev_targp != NULL);
  
  	/*
  	 * Allocate a (locked) buffer to hold the superblock.
  	 * This will be kept around at all times to optimize
  	 * access to the superblock.
  	 */
  	sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);

  
  reread:
  	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
  					XFS_SB_DADDR, sector_size, 0);
  	if (!bp) {

  		if (loud)
  			xfs_warn(mp, "SB buffer read failed");

  		return EIO;

  	}

  
  	/*
  	 * Initialize the mount structure from the superblock.
  	 * But first do some basic consistency checking.
  	 */

  	xfs_sb_from_disk(&mp->m_sb, XFS_BUF_TO_SBP(bp));

  	error = xfs_mount_validate_sb(mp, &(mp->m_sb), flags);

  	if (error) {

  		if (loud)
  			xfs_warn(mp, "SB validate failed");

  		goto release_buf;

  	}
  
  	/*
  	 * We must be able to do sector-sized and sector-aligned IO.
  	 */
  	if (sector_size > mp->m_sb.sb_sectsize) {

  		if (loud)
  			xfs_warn(mp, "device supports %u byte sectors (not %u)",
  				sector_size, mp->m_sb.sb_sectsize);

  		error = ENOSYS;

  		goto release_buf;

  	}
  
  	/*
  	 * If device sector size is smaller than the superblock size,
  	 * re-read the superblock so the buffer is correctly sized.
  	 */
  	if (sector_size < mp->m_sb.sb_sectsize) {

  		xfs_buf_relse(bp);
  		sector_size = mp->m_sb.sb_sectsize;

  		goto reread;

  	}

  	/* Initialize per-cpu counters */
  	xfs_icsb_reinit_counters(mp);

  	mp->m_sb_bp = bp;

  	xfs_buf_unlock(bp);

  	return 0;

  release_buf:
  	xfs_buf_relse(bp);

  	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 1 failed");

  				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) {

  					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,
  		"stripe alignment turned off: 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
   */
  STATIC void
  xfs_set_maxicount(xfs_mount_t *mp)
  {
  	xfs_sb_t	*sbp = &(mp->m_sb);
  	__uint64_t	icount;

  	if (sbp->sb_imax_pct) {
  		/*
  		 * Make sure the maximum inode count is a multiple
  		 * of the units we allocate inodes in.

  		 */

  		icount = sbp->sb_dblocks * sbp->sb_imax_pct;
  		do_div(icount, 100);
  		do_div(icount, mp->m_ialloc_blks);
  		mp->m_maxicount = (icount * mp->m_ialloc_blks)  <<
  				   sbp->sb_inopblog;

  	} else {

  		mp->m_maxicount = 0;

  	}

  }
  
  /*
   * Set the default minimum read and write sizes unless
   * already specified in a mount option.
   * We use smaller I/O sizes when the file system
   * is being used for NFS service (wsync mount option).
   */
  STATIC void
  xfs_set_rw_sizes(xfs_mount_t *mp)
  {
  	xfs_sb_t	*sbp = &(mp->m_sb);
  	int		readio_log, writeio_log;

  	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
  		if (mp->m_flags & XFS_MOUNT_WSYNC) {
  			readio_log = XFS_WSYNC_READIO_LOG;
  			writeio_log = XFS_WSYNC_WRITEIO_LOG;
  		} else {
  			readio_log = XFS_READIO_LOG_LARGE;
  			writeio_log = XFS_WRITEIO_LOG_LARGE;
  		}
  	} else {
  		readio_log = mp->m_readio_log;
  		writeio_log = mp->m_writeio_log;
  	}

  	if (sbp->sb_blocklog > readio_log) {
  		mp->m_readio_log = sbp->sb_blocklog;
  	} else {
  		mp->m_readio_log = readio_log;
  	}
  	mp->m_readio_blocks = 1 << (mp->m_readio_log - sbp->sb_blocklog);
  	if (sbp->sb_blocklog > writeio_log) {
  		mp->m_writeio_log = sbp->sb_blocklog;
  	} else {
  		mp->m_writeio_log = writeio_log;
  	}
  	mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);

  }

  /*

   * precalculate the low space thresholds for dynamic speculative preallocation.
   */
  void
  xfs_set_low_space_thresholds(
  	struct xfs_mount	*mp)
  {
  	int i;
  
  	for (i = 0; i < XFS_LOWSP_MAX; i++) {
  		__uint64_t space = mp->m_sb.sb_dblocks;
  
  		do_div(space, 100);
  		mp->m_low_space[i] = space * (i + 1);
  	}
  }
  
  
  /*

   * Set whether we're using inode alignment.
   */
  STATIC void
  xfs_set_inoalignment(xfs_mount_t *mp)
  {

  	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;
  	else
  		mp->m_inoalign_mask = 0;
  	/*
  	 * If we are using stripe alignment, check whether
  	 * the stripe unit is a multiple of the inode alignment
  	 */
  	if (mp->m_dalign && mp->m_inoalign_mask &&
  	    !(mp->m_dalign & mp->m_inoalign_mask))
  		mp->m_sinoalign = mp->m_dalign;
  	else
  		mp->m_sinoalign = 0;

  }
  
  /*
   * Check that the data (and log if separate) are an ok size.
   */
  STATIC int

  xfs_check_sizes(xfs_mount_t *mp)

  {
  	xfs_buf_t	*bp;
  	xfs_daddr_t	d;

  	d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
  	if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {

  		xfs_warn(mp, "filesystem size mismatch detected");

  		return XFS_ERROR(EFBIG);

  	}

  	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
  					d - XFS_FSS_TO_BB(mp, 1),
  					BBTOB(XFS_FSS_TO_BB(mp, 1)), 0);
  	if (!bp) {

  		xfs_warn(mp, "last sector read failed");

  		return EIO;

  	}

  	xfs_buf_relse(bp);

  	if (mp->m_logdev_targp != mp->m_ddev_targp) {

  		d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
  		if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {

  			xfs_warn(mp, "log size mismatch detected");

  			return XFS_ERROR(EFBIG);

  		}

  		bp = xfs_buf_read_uncached(mp, mp->m_logdev_targp,
  					d - XFS_FSB_TO_BB(mp, 1),
  					XFS_FSB_TO_B(mp, 1), 0);
  		if (!bp) {

  			xfs_warn(mp, "log device read failed");

  			return EIO;

  		}

  		xfs_buf_relse(bp);

  	}
  	return 0;
  }
  
  /*

   * Clear the quotaflags in memory and in the superblock.
   */
  int
  xfs_mount_reset_sbqflags(
  	struct xfs_mount	*mp)
  {
  	int			error;
  	struct xfs_trans	*tp;
  
  	mp->m_qflags = 0;
  
  	/*
  	 * It is OK to look at sb_qflags here in mount path,
  	 * without m_sb_lock.
  	 */
  	if (mp->m_sb.sb_qflags == 0)
  		return 0;
  	spin_lock(&mp->m_sb_lock);
  	mp->m_sb.sb_qflags = 0;
  	spin_unlock(&mp->m_sb_lock);
  
  	/*
  	 * If the fs is readonly, let the incore superblock run
  	 * with quotas off but don't flush the update out to disk
  	 */
  	if (mp->m_flags & XFS_MOUNT_RDONLY)
  		return 0;
  
  #ifdef QUOTADEBUG

  	xfs_notice(mp, "Writing superblock quota changes");

  #endif
  
  	tp = xfs_trans_alloc(mp, XFS_TRANS_QM_SBCHANGE);
  	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
  				      XFS_DEFAULT_LOG_COUNT);
  	if (error) {
  		xfs_trans_cancel(tp, 0);

  		xfs_alert(mp, "%s: Superblock update failed!", __func__);

  		return error;
  	}
  
  	xfs_mod_sb(tp, XFS_SB_QFLAGS);
  	return xfs_trans_commit(tp, 0);
  }

  __uint64_t
  xfs_default_resblks(xfs_mount_t *mp)
  {
  	__uint64_t resblks;
  
  	/*

  	 * We default to 5% or 8192 fsbs of space reserved, whichever is
  	 * smaller.  This is intended to cover concurrent allocation
  	 * transactions when we initially hit enospc. These each require a 4
  	 * block reservation. Hence by default we cover roughly 2000 concurrent
  	 * allocation reservations.

  	 */
  	resblks = mp->m_sb.sb_dblocks;
  	do_div(resblks, 20);

  	resblks = min_t(__uint64_t, resblks, 8192);

  	return resblks;
  }

  /*

   * This function does the following on an initial mount of a file system:
   *	- reads the superblock from disk and init the mount struct
   *	- if we're a 32-bit kernel, do a size check on the superblock
   *		so we don't mount terabyte filesystems
   *	- init mount struct realtime fields
   *	- allocate inode hash table for fs
   *	- init directory manager
   *	- perform recovery and init the log manager
   */
  int
  xfs_mountfs(

  	xfs_mount_t	*mp)

  {
  	xfs_sb_t	*sbp = &(mp->m_sb);
  	xfs_inode_t	*rip;

  	__uint64_t	resblks;

  	uint		quotamount = 0;
  	uint		quotaflags = 0;

  	int		error = 0;

  	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)) {

  		xfs_warn(mp, "correcting sb_features alignment problem");

  		sbp->sb_features2 |= sbp->sb_bad_features2;

  		sbp->sb_bad_features2 = sbp->sb_features2;

  		mp->m_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_NOATTR2))

  			mp->m_flags |= XFS_MOUNT_ATTR2;

  	}
  
  	if (xfs_sb_version_hasattr2(&mp->m_sb) &&
  	   (mp->m_flags & XFS_MOUNT_NOATTR2)) {
  		xfs_sb_version_removeattr2(&mp->m_sb);

  		mp->m_update_flags |= XFS_SB_FEATURES2;

  		/* update sb_versionnum for the clearing of the morebits */
  		if (!sbp->sb_features2)

  			mp->m_update_flags |= XFS_SB_VERSIONNUM;

  	}
  
  	/*

  	 * 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
  	 * to be aligned at stripe boundary.
  	 */

  	error = xfs_update_alignment(mp);

  	if (error)

  		goto out;

  
  	xfs_alloc_compute_maxlevels(mp);
  	xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
  	xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
  	xfs_ialloc_compute_maxlevels(mp);
  
  	xfs_set_maxicount(mp);
  
  	mp->m_maxioffset = xfs_max_file_offset(sbp->sb_blocklog);

  	error = xfs_uuid_mount(mp);
  	if (error)
  		goto out;

  
  	/*

  	 * Set the minimum read and write sizes
  	 */
  	xfs_set_rw_sizes(mp);

  	/* set the low space thresholds for dynamic preallocation */
  	xfs_set_low_space_thresholds(mp);

  	/*
  	 * Set the inode cluster size.
  	 * This may still be overridden by the file system
  	 * block size if it is larger than the chosen cluster size.
  	 */
  	mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
  
  	/*
  	 * Set inode alignment fields
  	 */
  	xfs_set_inoalignment(mp);
  
  	/*
  	 * Check that the data (and log if separate) are an ok size.
  	 */

  	error = xfs_check_sizes(mp);

  	if (error)

  		goto out_remove_uuid;

  
  	/*

  	 * Initialize realtime fields in the mount structure
  	 */

  	error = xfs_rtmount_init(mp);
  	if (error) {

  		xfs_warn(mp, "RT mount failed");

  		goto out_remove_uuid;

  	}
  
  	/*

  	 *  Copies the low order bits of the timestamp and the randomly
  	 *  set "sequence" number out of a UUID.
  	 */
  	uuid_getnodeuniq(&sbp->sb_uuid, mp->m_fixedfsid);

  	mp->m_dmevmask = 0;	/* not persistent; set after each mount */

  	xfs_dir_mount(mp);

  
  	/*
  	 * Initialize the attribute manager's entries.
  	 */
  	mp->m_attr_magicpct = (mp->m_sb.sb_blocksize * 37) / 100;
  
  	/*
  	 * Initialize the precomputed transaction reservations values.
  	 */
  	xfs_trans_init(mp);
  
  	/*

  	 * Allocate and initialize the per-ag data.
  	 */

  	spin_lock_init(&mp->m_perag_lock);

  	INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);

  	error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
  	if (error) {

  		xfs_warn(mp, "Failed per-ag init: %d", error);

  		goto out_remove_uuid;

  	}

  	if (!sbp->sb_logblocks) {

  		xfs_warn(mp, "no log defined");

  		XFS_ERROR_REPORT("xfs_mountfs", XFS_ERRLEVEL_LOW, mp);
  		error = XFS_ERROR(EFSCORRUPTED);
  		goto out_free_perag;
  	}

  	/*
  	 * log's mount-time initialization. Perform 1st part recovery if needed
  	 */

  	error = xfs_log_mount(mp, mp->m_logdev_targp,
  			      XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
  			      XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
  	if (error) {

  		xfs_warn(mp, "log mount failed");

  		goto out_free_perag;

  	}
  
  	/*

  	 * Now the log is mounted, we know if it was an unclean shutdown or
  	 * not. If it was, with the first phase of recovery has completed, we
  	 * have consistent AG blocks on disk. We have not recovered EFIs yet,
  	 * but they are recovered transactionally in the second recovery phase
  	 * later.
  	 *
  	 * Hence we can safely re-initialise incore superblock counters from
  	 * the per-ag data. These may not be correct if the filesystem was not
  	 * cleanly unmounted, so we need to wait for recovery to finish before
  	 * doing this.
  	 *
  	 * If the filesystem was cleanly unmounted, then we can trust the
  	 * values in the superblock to be correct and we don't need to do
  	 * anything here.
  	 *
  	 * If we are currently making the filesystem, the initialisation will
  	 * fail as the perag data is in an undefined state.
  	 */

  	if (xfs_sb_version_haslazysbcount(&mp->m_sb) &&
  	    !XFS_LAST_UNMOUNT_WAS_CLEAN(mp) &&
  	     !mp->m_sb.sb_inprogress) {
  		error = xfs_initialize_perag_data(mp, sbp->sb_agcount);

  		if (error)
  			goto out_free_perag;

  	}

  	/*

  	 * Get and sanity-check the root inode.
  	 * Save the pointer to it in the mount structure.
  	 */

  	error = xfs_iget(mp, NULL, sbp->sb_rootino, 0, XFS_ILOCK_EXCL, &rip);

  	if (error) {

  		xfs_warn(mp, "failed to read root inode");

  		goto out_log_dealloc;

  	}
  
  	ASSERT(rip != NULL);

  
  	if (unlikely((rip->i_d.di_mode & S_IFMT) != S_IFDIR)) {

  		xfs_warn(mp, "corrupted root inode %llu: not a directory",

  			(unsigned long long)rip->i_ino);

  		xfs_iunlock(rip, XFS_ILOCK_EXCL);
  		XFS_ERROR_REPORT("xfs_mountfs_int(2)", XFS_ERRLEVEL_LOW,
  				 mp);
  		error = XFS_ERROR(EFSCORRUPTED);

  		goto out_rele_rip;

  	}
  	mp->m_rootip = rip;	/* save it */
  
  	xfs_iunlock(rip, XFS_ILOCK_EXCL);
  
  	/*
  	 * Initialize realtime inode pointers in the mount structure
  	 */

  	error = xfs_rtmount_inodes(mp);
  	if (error) {

  		/*
  		 * Free up the root inode.
  		 */

  		xfs_warn(mp, "failed to read RT inodes");

  		goto out_rele_rip;

  	}
  
  	/*

  	 * If this is a read-only mount defer the superblock updates until
  	 * the next remount into writeable mode.  Otherwise we would never
  	 * perform the update e.g. for the root filesystem.

  	 */

  	if (mp->m_update_flags && !(mp->m_flags & XFS_MOUNT_RDONLY)) {
  		error = xfs_mount_log_sb(mp, mp->m_update_flags);

  		if (error) {

  			xfs_warn(mp, "failed to write sb changes");

  			goto out_rtunmount;

  		}
  	}

  
  	/*
  	 * Initialise the XFS quota management subsystem for this mount
  	 */

  	if (XFS_IS_QUOTA_RUNNING(mp)) {
  		error = xfs_qm_newmount(mp, &quotamount, &quotaflags);
  		if (error)
  			goto out_rtunmount;
  	} else {
  		ASSERT(!XFS_IS_QUOTA_ON(mp));
  
  		/*
  		 * If a file system had quotas running earlier, but decided to
  		 * mount without -o uquota/pquota/gquota options, revoke the
  		 * quotachecked license.
  		 */
  		if (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_ACCT) {

  			xfs_notice(mp, "resetting quota flags");

  			error = xfs_mount_reset_sbqflags(mp);
  			if (error)
  				return error;
  		}
  	}

  
  	/*
  	 * Finish recovering the file system.  This part needed to be
  	 * delayed until after the root and real-time bitmap inodes
  	 * were consistently read in.
  	 */

  	error = xfs_log_mount_finish(mp);

  	if (error) {

  		xfs_warn(mp, "log mount finish failed");

  		goto out_rtunmount;

  	}
  
  	/*
  	 * Complete the quota initialisation, post-log-replay component.
  	 */

  	if (quotamount) {
  		ASSERT(mp->m_qflags == 0);
  		mp->m_qflags = quotaflags;
  
  		xfs_qm_mount_quotas(mp);
  	}

  	/*
  	 * Now we are mounted, reserve a small amount of unused space for
  	 * privileged transactions. This is needed so that transaction
  	 * space required for critical operations can dip into this pool
  	 * when at ENOSPC. This is needed for operations like create with
  	 * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
  	 * are not allowed to use this reserved space.

  	 *
  	 * This may drive us straight to ENOSPC on mount, but that implies
  	 * we were already there on the last unmount. Warn if this occurs.

  	 */

  	if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
  		resblks = xfs_default_resblks(mp);
  		error = xfs_reserve_blocks(mp, &resblks, NULL);
  		if (error)

  			xfs_warn(mp,
  	"Unable to allocate reserve blocks. Continuing without reserve pool.");

  	}

  	return 0;

   out_rtunmount:
  	xfs_rtunmount_inodes(mp);

   out_rele_rip:

  	IRELE(rip);

   out_log_dealloc:

  	xfs_log_unmount(mp);

   out_free_perag:

  	xfs_free_perag(mp);

   out_remove_uuid:

  	xfs_uuid_unmount(mp);

   out:

  	return error;
  }
  
  /*

   * This flushes out the inodes,dquots and the superblock, unmounts the
   * log and makes sure that incore structures are freed.
   */

  void
  xfs_unmountfs(
  	struct xfs_mount	*mp)

  {

  	__uint64_t		resblks;
  	int			error;

  	xfs_qm_unmount_quotas(mp);

  	xfs_rtunmount_inodes(mp);

  	IRELE(mp->m_rootip);

  	/*
  	 * We can potentially deadlock here if we have an inode cluster

  	 * that has been freed has its buffer still pinned in memory because

  	 * the transaction is still sitting in a iclog. The stale inodes
  	 * on that buffer will have their flush locks held until the
  	 * transaction hits the disk and the callbacks run. the inode
  	 * flush takes the flush lock unconditionally and with nothing to
  	 * push out the iclog we will never get that unlocked. hence we
  	 * need to force the log first.
  	 */

  	xfs_log_force(mp, XFS_LOG_SYNC);

  
  	/*
  	 * Do a delwri reclaim pass first so that as many dirty inodes are
  	 * queued up for IO as possible. Then flush the buffers before making
  	 * a synchronous path to catch all the remaining inodes are reclaimed.
  	 * This makes the reclaim process as quick as possible by avoiding
  	 * synchronous writeout and blocking on inodes already in the delwri
  	 * state as much as possible.
  	 */
  	xfs_reclaim_inodes(mp, 0);
  	XFS_bflush(mp->m_ddev_targp);
  	xfs_reclaim_inodes(mp, SYNC_WAIT);

  	xfs_qm_unmount(mp);

  	/*
  	 * Flush out the log synchronously so that we know for sure
  	 * that nothing is pinned.  This is important because bflush()
  	 * will skip pinned buffers.
  	 */

  	xfs_log_force(mp, XFS_LOG_SYNC);

  
  	xfs_binval(mp->m_ddev_targp);
  	if (mp->m_rtdev_targp) {
  		xfs_binval(mp->m_rtdev_targp);
  	}

  	/*
  	 * Unreserve any blocks we have so that when we unmount we don't account
  	 * the reserved free space as used. This is really only necessary for
  	 * lazy superblock counting because it trusts the incore superblock

  	 * counters to be absolutely correct on clean unmount.

  	 *
  	 * We don't bother correcting this elsewhere for lazy superblock
  	 * counting because on mount of an unclean filesystem we reconstruct the
  	 * correct counter value and this is irrelevant.
  	 *
  	 * For non-lazy counter filesystems, this doesn't matter at all because
  	 * we only every apply deltas to the superblock and hence the incore
  	 * value does not matter....
  	 */
  	resblks = 0;

  	error = xfs_reserve_blocks(mp, &resblks, NULL);
  	if (error)

  		xfs_warn(mp, "Unable to free reserved block pool. "

  				"Freespace may not be correct on next mount.");

  	error = xfs_log_sbcount(mp, 1);
  	if (error)

  		xfs_warn(mp, "Unable to update superblock counters. "

  				"Freespace may not be correct on next mount.");

  	xfs_unmountfs_writesb(mp);

  	xfs_unmountfs_wait(mp); 		/* wait for async bufs */

  	xfs_log_unmount_write(mp);
  	xfs_log_unmount(mp);

  	xfs_uuid_unmount(mp);

  #if defined(DEBUG)

  	xfs_errortag_clearall(mp, 0);

  #endif

  	xfs_free_perag(mp);

  }

  STATIC void

  xfs_unmountfs_wait(xfs_mount_t *mp)
  {
  	if (mp->m_logdev_targp != mp->m_ddev_targp)
  		xfs_wait_buftarg(mp->m_logdev_targp);
  	if (mp->m_rtdev_targp)
  		xfs_wait_buftarg(mp->m_rtdev_targp);
  	xfs_wait_buftarg(mp->m_ddev_targp);
  }
  
  int

  xfs_fs_writable(xfs_mount_t *mp)
  {

  	return !(xfs_test_for_freeze(mp) || XFS_FORCED_SHUTDOWN(mp) ||

  		(mp->m_flags & XFS_MOUNT_RDONLY));

  }
  
  /*
   * xfs_log_sbcount
   *
   * Called either periodically to keep the on disk superblock values
   * roughly up to date or from unmount to make sure the values are
   * correct on a clean unmount.
   *
   * Note this code can be called during the process of freezing, so
   * we may need to use the transaction allocator which does not not
   * block when the transaction subsystem is in its frozen state.
   */
  int
  xfs_log_sbcount(
  	xfs_mount_t	*mp,
  	uint		sync)
  {
  	xfs_trans_t	*tp;
  	int		error;
  
  	if (!xfs_fs_writable(mp))
  		return 0;

  	xfs_icsb_sync_counters(mp, 0);

  
  	/*
  	 * we don't need to do this if we are updating the superblock
  	 * counters on every modification.
  	 */
  	if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
  		return 0;

  	tp = _xfs_trans_alloc(mp, XFS_TRANS_SB_COUNT, KM_SLEEP);

  	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
  					XFS_DEFAULT_LOG_COUNT);
  	if (error) {
  		xfs_trans_cancel(tp, 0);
  		return error;
  	}
  
  	xfs_mod_sb(tp, XFS_SB_IFREE | XFS_SB_ICOUNT | XFS_SB_FDBLOCKS);
  	if (sync)
  		xfs_trans_set_sync(tp);

  	error = xfs_trans_commit(tp, 0);
  	return error;

  }
  
  int

  xfs_unmountfs_writesb(xfs_mount_t *mp)
  {
  	xfs_buf_t	*sbp;

  	int		error = 0;
  
  	/*
  	 * skip superblock write if fs is read-only, or
  	 * if we are doing a forced umount.
  	 */

  	if (!((mp->m_flags & XFS_MOUNT_RDONLY) ||

  		XFS_FORCED_SHUTDOWN(mp))) {

  		sbp = xfs_getsb(mp, 0);

  		XFS_BUF_UNDONE(sbp);
  		XFS_BUF_UNREAD(sbp);
  		XFS_BUF_UNDELAYWRITE(sbp);
  		XFS_BUF_WRITE(sbp);
  		XFS_BUF_UNASYNC(sbp);
  		ASSERT(XFS_BUF_TARGET(sbp) == mp->m_ddev_targp);
  		xfsbdstrat(mp, sbp);

  		error = xfs_buf_iowait(sbp);

  		if (error)
  			xfs_ioerror_alert("xfs_unmountfs_writesb",
  					  mp, sbp, XFS_BUF_ADDR(sbp));

  		xfs_buf_relse(sbp);

  	}

  	return error;

  }
  
  /*
   * 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_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.
   * Fields are not allowed to dip below zero, so if the delta would
   * do this do not apply it and return EINVAL.
   *

   * The m_sb_lock must be held when this routine is called.

   */

  STATIC int

  xfs_mod_incore_sb_unlocked(
  	xfs_mount_t	*mp,
  	xfs_sb_field_t	field,
  	int64_t		delta,
  	int		rsvd)

  {
  	int		scounter;	/* short counter for 32 bit fields */
  	long long	lcounter;	/* long counter for 64 bit fields */
  	long long	res_used, rem;
  
  	/*
  	 * With the in-core superblock spin lock held, switch
  	 * on the indicated field.  Apply the delta to the
  	 * proper field.  If the fields value would dip below
  	 * 0, then do not apply the delta and return EINVAL.
  	 */
  	switch (field) {
  	case XFS_SBS_ICOUNT:
  		lcounter = (long long)mp->m_sb.sb_icount;
  		lcounter += delta;
  		if (lcounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_icount = lcounter;

  		return 0;

  	case XFS_SBS_IFREE:
  		lcounter = (long long)mp->m_sb.sb_ifree;
  		lcounter += delta;
  		if (lcounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_ifree = lcounter;

  		return 0;

  	case XFS_SBS_FDBLOCKS:

  		lcounter = (long long)
  			mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);

  		res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
  
  		if (delta > 0) {		/* Putting blocks back */
  			if (res_used > delta) {
  				mp->m_resblks_avail += delta;
  			} else {
  				rem = delta - res_used;
  				mp->m_resblks_avail = mp->m_resblks;
  				lcounter += rem;
  			}
  		} else {				/* Taking blocks away */

  			lcounter += delta;

  			if (lcounter >= 0) {
  				mp->m_sb.sb_fdblocks = lcounter +
  							XFS_ALLOC_SET_ASIDE(mp);
  				return 0;
  			}

  			/*
  			 * We are out of blocks, use any available reserved
  			 * blocks if were allowed to.
  			 */
  			if (!rsvd)
  				return XFS_ERROR(ENOSPC);

  			lcounter = (long long)mp->m_resblks_avail + delta;
  			if (lcounter >= 0) {
  				mp->m_resblks_avail = lcounter;
  				return 0;

  			}

  			printk_once(KERN_WARNING
  				"Filesystem \"%s\": reserve blocks depleted! "
  				"Consider increasing reserve pool size.",
  				mp->m_fsname);
  			return XFS_ERROR(ENOSPC);

  		}

  		mp->m_sb.sb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);

  		return 0;

  	case XFS_SBS_FREXTENTS:
  		lcounter = (long long)mp->m_sb.sb_frextents;
  		lcounter += delta;
  		if (lcounter < 0) {

  			return XFS_ERROR(ENOSPC);

  		}
  		mp->m_sb.sb_frextents = lcounter;

  		return 0;

  	case XFS_SBS_DBLOCKS:
  		lcounter = (long long)mp->m_sb.sb_dblocks;
  		lcounter += delta;
  		if (lcounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_dblocks = lcounter;

  		return 0;

  	case XFS_SBS_AGCOUNT:
  		scounter = mp->m_sb.sb_agcount;
  		scounter += delta;
  		if (scounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_agcount = scounter;

  		return 0;

  	case XFS_SBS_IMAX_PCT:
  		scounter = mp->m_sb.sb_imax_pct;
  		scounter += delta;
  		if (scounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_imax_pct = scounter;

  		return 0;

  	case XFS_SBS_REXTSIZE:
  		scounter = mp->m_sb.sb_rextsize;
  		scounter += delta;
  		if (scounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_rextsize = scounter;

  		return 0;

  	case XFS_SBS_RBMBLOCKS:
  		scounter = mp->m_sb.sb_rbmblocks;
  		scounter += delta;
  		if (scounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_rbmblocks = scounter;

  		return 0;

  	case XFS_SBS_RBLOCKS:
  		lcounter = (long long)mp->m_sb.sb_rblocks;
  		lcounter += delta;
  		if (lcounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_rblocks = lcounter;

  		return 0;

  	case XFS_SBS_REXTENTS:
  		lcounter = (long long)mp->m_sb.sb_rextents;
  		lcounter += delta;
  		if (lcounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_rextents = lcounter;

  		return 0;

  	case XFS_SBS_REXTSLOG:
  		scounter = mp->m_sb.sb_rextslog;
  		scounter += delta;
  		if (scounter < 0) {
  			ASSERT(0);

  			return XFS_ERROR(EINVAL);

  		}
  		mp->m_sb.sb_rextslog = scounter;

  		return 0;

  	default:
  		ASSERT(0);

  		return XFS_ERROR(EINVAL);

  	}
  }
  
  /*
   * xfs_mod_incore_sb() is used to change a field in the in-core
   * superblock structure by the specified delta.  This modification

   * is protected by the m_sb_lock.  Just use the xfs_mod_incore_sb_unlocked()

   * routine to do the work.
   */
  int

  xfs_mod_incore_sb(

  	struct xfs_mount	*mp,
  	xfs_sb_field_t		field,
  	int64_t			delta,
  	int			rsvd)

  {

  	int			status;

  #ifdef HAVE_PERCPU_SB

  	ASSERT(field < XFS_SBS_ICOUNT || field > XFS_SBS_FDBLOCKS);

  #endif

  	spin_lock(&mp->m_sb_lock);
  	status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
  	spin_unlock(&mp->m_sb_lock);

  	return status;

  }
  
  /*

   * Change more than one field in the in-core superblock structure at a time.

   *

   * The fields and changes to those fields are specified in the array of
   * xfs_mod_sb structures passed in.  Either all of the specified deltas
   * will be applied or none of them will.  If any modified field dips below 0,
   * then all modifications will be backed out and EINVAL will be returned.
   *
   * Note that this function may not be used for the superblock values that
   * are tracked with the in-memory per-cpu counters - a direct call to
   * xfs_icsb_modify_counters is required for these.

   */
  int

  xfs_mod_incore_sb_batch(
  	struct xfs_mount	*mp,
  	xfs_mod_sb_t		*msb,
  	uint			nmsb,
  	int			rsvd)

  {

  	xfs_mod_sb_t		*msbp = &msb[0];
  	int			error = 0;

  
  	/*

  	 * Loop through the array of mod structures and apply each individually.
  	 * If any fail, then back out all those which have already been applied.
  	 * Do all of this within the scope of the m_sb_lock so that all of the
  	 * changes will be atomic.

  	 */

  	spin_lock(&mp->m_sb_lock);

  	for (msbp = &msbp[0]; msbp < (msb + nmsb); msbp++) {

  		ASSERT(msbp->msb_field < XFS_SBS_ICOUNT ||
  		       msbp->msb_field > XFS_SBS_FDBLOCKS);

  		error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
  						   msbp->msb_delta, rsvd);
  		if (error)
  			goto unwind;

  	}

  	spin_unlock(&mp->m_sb_lock);
  	return 0;

  unwind:
  	while (--msbp >= msb) {
  		error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
  						   -msbp->msb_delta, rsvd);
  		ASSERT(error == 0);

  	}

  	spin_unlock(&mp->m_sb_lock);

  	return error;

  }
  
  /*
   * xfs_getsb() is called to obtain the buffer for the superblock.
   * The buffer is returned locked and read in from disk.
   * The buffer should be released with a call to xfs_brelse().
   *
   * If the flags parameter is BUF_TRYLOCK, then we'll only return
   * the superblock buffer if it can be locked without sleeping.
   * If it can't then we'll return NULL.
   */
  xfs_buf_t *
  xfs_getsb(
  	xfs_mount_t	*mp,
  	int		flags)
  {
  	xfs_buf_t	*bp;
  
  	ASSERT(mp->m_sb_bp != NULL);
  	bp = mp->m_sb_bp;

  	if (flags & XBF_TRYLOCK) {

  		if (!XFS_BUF_CPSEMA(bp)) {
  			return NULL;
  		}
  	} else {
  		XFS_BUF_PSEMA(bp, PRIBIO);
  	}
  	XFS_BUF_HOLD(bp);
  	ASSERT(XFS_BUF_ISDONE(bp));

  	return bp;

  }
  
  /*
   * Used to free the superblock along various error paths.
   */
  void
  xfs_freesb(

  	struct xfs_mount	*mp)

  {

  	struct xfs_buf		*bp = mp->m_sb_bp;

  	xfs_buf_lock(bp);

  	mp->m_sb_bp = NULL;

  	xfs_buf_relse(bp);

  }
  
  /*

   * Used to log changes to the superblock unit and width fields which could

   * be altered by the mount options, as well as any potential sb_features2
   * fixup. Only the first superblock is updated.

   */

  int

  xfs_mount_log_sb(

  	xfs_mount_t	*mp,
  	__int64_t	fields)
  {
  	xfs_trans_t	*tp;

  	int		error;

  	ASSERT(fields & (XFS_SB_UNIT | XFS_SB_WIDTH | XFS_SB_UUID |

  			 XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2 |
  			 XFS_SB_VERSIONNUM));

  
  	tp = xfs_trans_alloc(mp, XFS_TRANS_SB_UNIT);

  	error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
  				XFS_DEFAULT_LOG_COUNT);
  	if (error) {