/*

   * Copyright (c) 2000-2006 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_mount.h"

  #include "xfs_bmap_btree.h"

  #include "xfs_dinode.h"

  #include "xfs_inode.h"

  #include "xfs_inode_item.h"

  #include "xfs_bmap.h"

  #include "xfs_itable.h"
  #include "xfs_dfrag.h"
  #include "xfs_error.h"

  #include "xfs_vnodeops.h"

  #include "xfs_trace.h"

  
  static int xfs_swap_extents(
  	xfs_inode_t	*ip,	/* target inode */
  	xfs_inode_t	*tip,	/* tmp inode */
  	xfs_swapext_t	*sxp);

  /*

   * ioctl interface for swapext

   */
  int
  xfs_swapext(

  	xfs_swapext_t	*sxp)

  {

  	xfs_inode_t     *ip, *tip;

  	struct file	*file, *tmp_file;

  	int		error = 0;

  	/* Pull information for the target fd */

  	file = fget((int)sxp->sx_fdtarget);
  	if (!file) {

  		error = XFS_ERROR(EINVAL);

  		goto out;

  	}

  	if (!(file->f_mode & FMODE_WRITE) ||
  	    !(file->f_mode & FMODE_READ) ||
  	    (file->f_flags & O_APPEND)) {

  		error = XFS_ERROR(EBADF);
  		goto out_put_file;
  	}

  	tmp_file = fget((int)sxp->sx_fdtmp);
  	if (!tmp_file) {

  		error = XFS_ERROR(EINVAL);

  		goto out_put_file;

  	}

  	if (!(tmp_file->f_mode & FMODE_WRITE) ||

  	    !(tmp_file->f_mode & FMODE_READ) ||

  	    (tmp_file->f_flags & O_APPEND)) {

  		error = XFS_ERROR(EBADF);

  		goto out_put_tmp_file;

  	}

  	if (IS_SWAPFILE(file->f_path.dentry->d_inode) ||

  	    IS_SWAPFILE(tmp_file->f_path.dentry->d_inode)) {

  		error = XFS_ERROR(EINVAL);

  		goto out_put_tmp_file;

  	}

  	ip = XFS_I(file->f_path.dentry->d_inode);

  	tip = XFS_I(tmp_file->f_path.dentry->d_inode);

  
  	if (ip->i_mount != tip->i_mount) {

  		error = XFS_ERROR(EINVAL);

  		goto out_put_tmp_file;

  	}
  
  	if (ip->i_ino == tip->i_ino) {

  		error = XFS_ERROR(EINVAL);

  		goto out_put_tmp_file;

  	}

  	if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
  		error = XFS_ERROR(EIO);

  		goto out_put_tmp_file;

  	}

  	error = xfs_swap_extents(ip, tip, sxp);

   out_put_tmp_file:
  	fput(tmp_file);

   out_put_file:
  	fput(file);

   out:

  	return error;
  }

  /*
   * We need to check that the format of the data fork in the temporary inode is
   * valid for the target inode before doing the swap. This is not a problem with
   * attr1 because of the fixed fork offset, but attr2 has a dynamically sized
   * data fork depending on the space the attribute fork is taking so we can get
   * invalid formats on the target inode.
   *
   * E.g. target has space for 7 extents in extent format, temp inode only has
   * space for 6.  If we defragment down to 7 extents, then the tmp format is a
   * btree, but when swapped it needs to be in extent format. Hence we can't just
   * blindly swap data forks on attr2 filesystems.
   *
   * Note that we check the swap in both directions so that we don't end up with
   * a corrupt temporary inode, either.
   *
   * Note that fixing the way xfs_fsr sets up the attribute fork in the source
   * inode will prevent this situation from occurring, so all we do here is
   * reject and log the attempt. basically we are putting the responsibility on
   * userspace to get this right.
   */
  static int
  xfs_swap_extents_check_format(
  	xfs_inode_t	*ip,	/* target inode */
  	xfs_inode_t	*tip)	/* tmp inode */
  {
  
  	/* Should never get a local format */
  	if (ip->i_d.di_format == XFS_DINODE_FMT_LOCAL ||
  	    tip->i_d.di_format == XFS_DINODE_FMT_LOCAL)
  		return EINVAL;
  
  	/*
  	 * if the target inode has less extents that then temporary inode then
  	 * why did userspace call us?
  	 */
  	if (ip->i_d.di_nextents < tip->i_d.di_nextents)
  		return EINVAL;
  
  	/*
  	 * if the target inode is in extent form and the temp inode is in btree
  	 * form then we will end up with the target inode in the wrong format
  	 * as we already know there are less extents in the temp inode.
  	 */
  	if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
  	    tip->i_d.di_format == XFS_DINODE_FMT_BTREE)
  		return EINVAL;
  
  	/* Check temp in extent form to max in target */
  	if (tip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
  	    XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK) > ip->i_df.if_ext_max)
  		return EINVAL;
  
  	/* Check target in extent form to max in temp */
  	if (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS &&
  	    XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK) > tip->i_df.if_ext_max)
  		return EINVAL;

  	/*
  	 * If we are in a btree format, check that the temp root block will fit
  	 * in the target and that it has enough extents to be in btree format
  	 * in the target.
  	 *
  	 * Note that we have to be careful to allow btree->extent conversions
  	 * (a common defrag case) which will occur when the temp inode is in
  	 * extent format...
  	 */

  	if (tip->i_d.di_format == XFS_DINODE_FMT_BTREE &&

  	    ((XFS_IFORK_BOFF(ip) &&
  	      tip->i_df.if_broot_bytes > XFS_IFORK_BOFF(ip)) ||
  	     XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK) <= ip->i_df.if_ext_max))

  		return EINVAL;

  	/* Reciprocal target->temp btree format checks */

  	if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE &&

  	    ((XFS_IFORK_BOFF(tip) &&
  	      ip->i_df.if_broot_bytes > XFS_IFORK_BOFF(tip)) ||
  	     XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK) <= tip->i_df.if_ext_max))

  		return EINVAL;
  
  	return 0;
  }

  static int

  xfs_swap_extents(

  	xfs_inode_t	*ip,	/* target inode */
  	xfs_inode_t	*tip,	/* tmp inode */

  	xfs_swapext_t	*sxp)
  {

  	xfs_mount_t	*mp = ip->i_mount;

  	xfs_trans_t	*tp;
  	xfs_bstat_t	*sbp = &sxp->sx_stat;

  	xfs_ifork_t	*tempifp, *ifp, *tifp;
  	int		ilf_fields, tilf_fields;

  	int		error = 0;
  	int		aforkblks = 0;
  	int		taforkblks = 0;
  	__uint64_t	tmp;

  	tempifp = kmem_alloc(sizeof(xfs_ifork_t), KM_MAYFAIL);
  	if (!tempifp) {
  		error = XFS_ERROR(ENOMEM);

  		goto out;

  	}

  	/*
  	 * we have to do two separate lock calls here to keep lockdep
  	 * happy. If we try to get all the locks in one call, lock will
  	 * report false positives when we drop the ILOCK and regain them
  	 * below.
  	 */
  	xfs_lock_two_inodes(ip, tip, XFS_IOLOCK_EXCL);
  	xfs_lock_two_inodes(ip, tip, XFS_ILOCK_EXCL);

  	/* Verify that both files have the same format */
  	if ((ip->i_d.di_mode & S_IFMT) != (tip->i_d.di_mode & S_IFMT)) {
  		error = XFS_ERROR(EINVAL);

  		goto out_unlock;

  	}
  
  	/* Verify both files are either real-time or non-realtime */

  	if (XFS_IS_REALTIME_INODE(ip) != XFS_IS_REALTIME_INODE(tip)) {

  		error = XFS_ERROR(EINVAL);

  		goto out_unlock;

  	}

  	if (VN_CACHED(VFS_I(tip)) != 0) {

  		error = xfs_flushinval_pages(tip, 0, -1,
  				FI_REMAPF_LOCKED);

  		if (error)

  			goto out_unlock;

  	}

  
  	/* Verify O_DIRECT for ftmp */

  	if (VN_CACHED(VFS_I(tip)) != 0) {

  		error = XFS_ERROR(EINVAL);

  		goto out_unlock;

  	}
  
  	/* Verify all data are being swapped */

  	if (sxp->sx_offset != 0 ||
  	    sxp->sx_length != ip->i_d.di_size ||
  	    sxp->sx_length != tip->i_d.di_size) {

  		error = XFS_ERROR(EFAULT);

  		goto out_unlock;

  	}

  	trace_xfs_swap_extent_before(ip, 0);
  	trace_xfs_swap_extent_before(tip, 1);

  	/* check inode formats now that data is flushed */
  	error = xfs_swap_extents_check_format(ip, tip);
  	if (error) {

  		xfs_notice(mp,

  		    "%s: inode 0x%llx format is incompatible for exchanging.",

  				__func__, ip->i_ino);

  		goto out_unlock;

  	}
  
  	/*
  	 * Compare the current change & modify times with that
  	 * passed in.  If they differ, we abort this swap.
  	 * This is the mechanism used to ensure the calling
  	 * process that the file was not changed out from
  	 * under it.
  	 */

  	if ((sbp->bs_ctime.tv_sec != VFS_I(ip)->i_ctime.tv_sec) ||
  	    (sbp->bs_ctime.tv_nsec != VFS_I(ip)->i_ctime.tv_nsec) ||
  	    (sbp->bs_mtime.tv_sec != VFS_I(ip)->i_mtime.tv_sec) ||
  	    (sbp->bs_mtime.tv_nsec != VFS_I(ip)->i_mtime.tv_nsec)) {

  		error = XFS_ERROR(EBUSY);

  		goto out_unlock;

  	}
  
  	/* We need to fail if the file is memory mapped.  Once we have tossed
  	 * all existing pages, the page fault will have no option
  	 * but to go to the filesystem for pages. By making the page fault call

  	 * vop_read (or write in the case of autogrow) they block on the iolock

  	 * until we have switched the extents.
  	 */

  	if (VN_MAPPED(VFS_I(ip))) {

  		error = XFS_ERROR(EBUSY);

  		goto out_unlock;

  	}
  
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	xfs_iunlock(tip, XFS_ILOCK_EXCL);
  
  	/*
  	 * There is a race condition here since we gave up the
  	 * ilock.  However, the data fork will not change since
  	 * we have the iolock (locked for truncation too) so we
  	 * are safe.  We don't really care if non-io related
  	 * fields change.
  	 */

  	xfs_tosspages(ip, 0, -1, FI_REMAPF);

  
  	tp = xfs_trans_alloc(mp, XFS_TRANS_SWAPEXT);
  	if ((error = xfs_trans_reserve(tp, 0,
  				     XFS_ICHANGE_LOG_RES(mp), 0,
  				     0, 0))) {
  		xfs_iunlock(ip,  XFS_IOLOCK_EXCL);
  		xfs_iunlock(tip, XFS_IOLOCK_EXCL);
  		xfs_trans_cancel(tp, 0);

  		goto out;

  	}

  	xfs_lock_two_inodes(ip, tip, XFS_ILOCK_EXCL);

  
  	/*
  	 * Count the number of extended attribute blocks
  	 */
  	if ( ((XFS_IFORK_Q(ip) != 0) && (ip->i_d.di_anextents > 0)) &&
  	     (ip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL)) {
  		error = xfs_bmap_count_blocks(tp, ip, XFS_ATTR_FORK, &aforkblks);

  		if (error)
  			goto out_trans_cancel;

  	}
  	if ( ((XFS_IFORK_Q(tip) != 0) && (tip->i_d.di_anextents > 0)) &&
  	     (tip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL)) {
  		error = xfs_bmap_count_blocks(tp, tip, XFS_ATTR_FORK,
  			&taforkblks);

  		if (error)
  			goto out_trans_cancel;

  	}
  
  	/*
  	 * Swap the data forks of the inodes
  	 */
  	ifp = &ip->i_df;
  	tifp = &tip->i_df;

  	*tempifp = *ifp;	/* struct copy */
  	*ifp = *tifp;		/* struct copy */
  	*tifp = *tempifp;	/* struct copy */

  
  	/*

  	 * Fix the in-memory data fork values that are dependent on the fork
  	 * offset in the inode. We can't assume they remain the same as attr2
  	 * has dynamic fork offsets.
  	 */
  	ifp->if_ext_max = XFS_IFORK_SIZE(ip, XFS_DATA_FORK) /
  					(uint)sizeof(xfs_bmbt_rec_t);
  	tifp->if_ext_max = XFS_IFORK_SIZE(tip, XFS_DATA_FORK) /
  					(uint)sizeof(xfs_bmbt_rec_t);
  
  	/*

  	 * Fix the on-disk inode values
  	 */
  	tmp = (__uint64_t)ip->i_d.di_nblocks;
  	ip->i_d.di_nblocks = tip->i_d.di_nblocks - taforkblks + aforkblks;
  	tip->i_d.di_nblocks = tmp + taforkblks - aforkblks;
  
  	tmp = (__uint64_t) ip->i_d.di_nextents;
  	ip->i_d.di_nextents = tip->i_d.di_nextents;
  	tip->i_d.di_nextents = tmp;
  
  	tmp = (__uint64_t) ip->i_d.di_format;
  	ip->i_d.di_format = tip->i_d.di_format;
  	tip->i_d.di_format = tmp;

  	/*
  	 * The extents in the source inode could still contain speculative
  	 * preallocation beyond EOF (e.g. the file is open but not modified
  	 * while defrag is in progress). In that case, we need to copy over the
  	 * number of delalloc blocks the data fork in the source inode is
  	 * tracking beyond EOF so that when the fork is truncated away when the
  	 * temporary inode is unlinked we don't underrun the i_delayed_blks
  	 * counter on that inode.
  	 */
  	ASSERT(tip->i_delayed_blks == 0);
  	tip->i_delayed_blks = ip->i_delayed_blks;
  	ip->i_delayed_blks = 0;

  	ilf_fields = XFS_ILOG_CORE;
  
  	switch(ip->i_d.di_format) {
  	case XFS_DINODE_FMT_EXTENTS:
  		/* If the extents fit in the inode, fix the
  		 * pointer.  Otherwise it's already NULL or
  		 * pointing to the extent.
  		 */
  		if (ip->i_d.di_nextents <= XFS_INLINE_EXTS) {
  			ifp->if_u1.if_extents =
  				ifp->if_u2.if_inline_ext;
  		}
  		ilf_fields |= XFS_ILOG_DEXT;
  		break;
  	case XFS_DINODE_FMT_BTREE:
  		ilf_fields |= XFS_ILOG_DBROOT;
  		break;
  	}
  
  	tilf_fields = XFS_ILOG_CORE;
  
  	switch(tip->i_d.di_format) {
  	case XFS_DINODE_FMT_EXTENTS:
  		/* If the extents fit in the inode, fix the
  		 * pointer.  Otherwise it's already NULL or
  		 * pointing to the extent.
  		 */
  		if (tip->i_d.di_nextents <= XFS_INLINE_EXTS) {
  			tifp->if_u1.if_extents =
  				tifp->if_u2.if_inline_ext;
  		}
  		tilf_fields |= XFS_ILOG_DEXT;
  		break;
  	case XFS_DINODE_FMT_BTREE:
  		tilf_fields |= XFS_ILOG_DBROOT;
  		break;
  	}

  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
  	xfs_trans_ijoin(tp, tip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

  
  	xfs_trans_log_inode(tp, ip,  ilf_fields);
  	xfs_trans_log_inode(tp, tip, tilf_fields);
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * transaction goes to disk before returning to the user.
  	 */

  	if (mp->m_flags & XFS_MOUNT_WSYNC)

  		xfs_trans_set_sync(tp);

  	error = xfs_trans_commit(tp, 0);

  	trace_xfs_swap_extent_after(ip, 0);
  	trace_xfs_swap_extent_after(tip, 1);

  out:
  	kmem_free(tempifp);

  	return error;

  out_unlock:
  	xfs_iunlock(ip,  XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
  	xfs_iunlock(tip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
  	goto out;

  out_trans_cancel:
  	xfs_trans_cancel(tp, 0);
  	goto out_unlock;

  }