text: /*
   * 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_shared.h"
  #include "xfs_format.h"
  #include "xfs_log_format.h"
  #include "xfs_trans_resv.h"
  #include "xfs_bit.h"
  #include "xfs_sb.h"
  #include "xfs_ag.h"
  #include "xfs_mount.h"
  #include "xfs_inode.h"
  #include "xfs_ialloc.h"
  #include "xfs_alloc.h"
  #include "xfs_error.h"
  #include "xfs_trace.h"
  #include "xfs_cksum.h"
  #include "xfs_trans.h"
  #include "xfs_buf_item.h"
  #include "xfs_dinode.h"
  #include "xfs_bmap_btree.h"
  #include "xfs_alloc_btree.h"
  #include "xfs_ialloc_btree.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 (xfs_sb_version_has_pquotino(sbp)) {
  		if (sbp->sb_qflags & (XFS_OQUOTA_ENFD | XFS_OQUOTA_CHKD)) {
  			xfs_notice(mp,
  			   "Version 5 of Super block has XFS_OQUOTA bits.");
  			return XFS_ERROR(EFSCORRUPTED);
  		}
  	} else if (sbp->sb_qflags & (XFS_PQUOTA_ENFD | XFS_GQUOTA_ENFD |
  				XFS_PQUOTA_CHKD | XFS_GQUOTA_CHKD)) {
  			xfs_notice(mp,
  "Superblock earlier than Version 5 has XFS_[PQ]UOTA_{ENFD|CHKD} bits.");
  			return XFS_ERROR(EFSCORRUPTED);
  	}
  
  	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_quota_from_disk(struct xfs_sb *sbp)
  {
  	/*
  	 * older mkfs doesn't initialize quota inodes to NULLFSINO. This
  	 * leads to in-core values having two different values for a quota
  	 * inode to be invalid: 0 and NULLFSINO. Change it to a single value
  	 * NULLFSINO.
  	 *
  	 * Note that this change affect only the in-core values. These
  	 * values are not written back to disk unless any quota information
  	 * is written to the disk. Even in that case, sb_pquotino field is
  	 * not written to disk unless the superblock supports pquotino.
  	 */
  	if (sbp->sb_uquotino == 0)
  		sbp->sb_uquotino = NULLFSINO;
  	if (sbp->sb_gquotino == 0)
  		sbp->sb_gquotino = NULLFSINO;
  	if (sbp->sb_pquotino == 0)
  		sbp->sb_pquotino = NULLFSINO;
  
  	/*
  	 * We need to do these manipilations only if we are working
  	 * with an older version of on-disk superblock.
  	 */
  	if (xfs_sb_version_has_pquotino(sbp))
  		return;
  
  	if (sbp->sb_qflags & XFS_OQUOTA_ENFD)
  		sbp->sb_qflags |= (sbp->sb_qflags & XFS_PQUOTA_ACCT) ?
  					XFS_PQUOTA_ENFD : XFS_GQUOTA_ENFD;
  	if (sbp->sb_qflags & XFS_OQUOTA_CHKD)
  		sbp->sb_qflags |= (sbp->sb_qflags & XFS_PQUOTA_ACCT) ?
  					XFS_PQUOTA_CHKD : XFS_GQUOTA_CHKD;
  	sbp->sb_qflags &= ~(XFS_OQUOTA_ENFD | XFS_OQUOTA_CHKD);
  
  	if (sbp->sb_qflags & XFS_PQUOTA_ACCT)  {
  		/*
  		 * In older version of superblock, on-disk superblock only
  		 * has sb_gquotino, and in-core superblock has both sb_gquotino
  		 * and sb_pquotino. But, only one of them is supported at any
  		 * point of time. So, if PQUOTA is set in disk superblock,
  		 * copy over sb_gquotino to sb_pquotino.
  		 */
  		sbp->sb_pquotino = sbp->sb_gquotino;
  		sbp->sb_gquotino = NULLFSINO;
  	}
  }
  
  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);
  }
  
  static inline void
  xfs_sb_quota_to_disk(
  	xfs_dsb_t	*to,
  	xfs_sb_t	*from,
  	__int64_t	*fields)
  {
  	__uint16_t	qflags = from->sb_qflags;
  
  	/*
  	 * We need to do these manipilations only if we are working
  	 * with an older version of on-disk superblock.
  	 */
  	if (xfs_sb_version_has_pquotino(from))
  		return;
  
  	if (*fields & XFS_SB_QFLAGS) {
  		/*
  		 * The in-core version of sb_qflags do not have
  		 * XFS_OQUOTA_* flags, whereas the on-disk version
  		 * does.  So, convert incore XFS_{PG}QUOTA_* flags
  		 * to on-disk XFS_OQUOTA_* flags.
  		 */
  		qflags &= ~(XFS_PQUOTA_ENFD | XFS_PQUOTA_CHKD |
  				XFS_GQUOTA_ENFD | XFS_GQUOTA_CHKD);
  
  		if (from->sb_qflags &
  				(XFS_PQUOTA_ENFD | XFS_GQUOTA_ENFD))
  			qflags |= XFS_OQUOTA_ENFD;
  		if (from->sb_qflags &
  				(XFS_PQUOTA_CHKD | XFS_GQUOTA_CHKD))
  			qflags |= XFS_OQUOTA_CHKD;
  		to->sb_qflags = cpu_to_be16(qflags);
  		*fields &= ~XFS_SB_QFLAGS;
  	}
  
  	/*
  	 * GQUOTINO and PQUOTINO cannot be used together in versions
  	 * of superblock that do not have pquotino. from->sb_flags
  	 * tells us which quota is active and should be copied to
  	 * disk.
  	 */
  	if ((*fields & XFS_SB_GQUOTINO) &&
  				(from->sb_qflags & XFS_GQUOTA_ACCT))
  		to->sb_gquotino = cpu_to_be64(from->sb_gquotino);
  	else if ((*fields & XFS_SB_PQUOTINO) &&
  				(from->sb_qflags & XFS_PQUOTA_ACCT))
  		to->sb_gquotino = cpu_to_be64(from->sb_pquotino);
  
  	*fields &= ~(XFS_SB_PQUOTINO | XFS_SB_GQUOTINO);
  }
  
  /*
   * 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;
  
  	xfs_sb_quota_to_disk(to, from, &fields);
  	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.
   *
   * However, past bugs (i.e. in growfs) left non-zeroed regions beyond the
   * last field in V4 secondary superblocks.  So for secondary superblocks,
   * we are more forgiving, and ignore CRC failures if the primary doesn't
   * indicate that the fs version is V5.
   */
  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))) {
  			/* Only fail bad secondaries on a known V5 filesystem */
  			if (bp->b_bn != XFS_SB_DADDR &&
  			    xfs_sb_version_hascrc(&mp->m_sb)) {
  				error = EFSCORRUPTED;
  				goto out_error;
  			}
  		}
  	}
  	error = xfs_sb_verify(bp, true);
  
  out_error:
  	if (error) {
  		if (error != EWRONGFS)
  			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, then 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(
  	struct xfs_mount *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);
  }
  