text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   * All Rights Reserved.
   */
  #include <linux/iversion.h>
  
  #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_sb.h"
  #include "xfs_mount.h"
  #include "xfs_defer.h"
  #include "xfs_inode.h"
  #include "xfs_dir2.h"
  #include "xfs_attr.h"
  #include "xfs_trans_space.h"
  #include "xfs_trans.h"
  #include "xfs_buf_item.h"
  #include "xfs_inode_item.h"
  #include "xfs_ialloc.h"
  #include "xfs_bmap.h"
  #include "xfs_bmap_util.h"
  #include "xfs_errortag.h"
  #include "xfs_error.h"
  #include "xfs_quota.h"
  #include "xfs_filestream.h"
  #include "xfs_trace.h"
  #include "xfs_icache.h"
  #include "xfs_symlink.h"
  #include "xfs_trans_priv.h"
  #include "xfs_log.h"
  #include "xfs_bmap_btree.h"
  #include "xfs_reflink.h"
  
  kmem_zone_t *xfs_inode_zone;
  
  /*
   * Used in xfs_itruncate_extents().  This is the maximum number of extents
   * freed from a file in a single transaction.
   */
  #define	XFS_ITRUNC_MAX_EXTENTS	2
  
  STATIC int xfs_iflush_int(struct xfs_inode *, struct xfs_buf *);
  STATIC int xfs_iunlink(struct xfs_trans *, struct xfs_inode *);
  STATIC int xfs_iunlink_remove(struct xfs_trans *, struct xfs_inode *);
  
  /*
   * helper function to extract extent size hint from inode
   */
  xfs_extlen_t
  xfs_get_extsz_hint(
  	struct xfs_inode	*ip)
  {
  	/*
  	 * No point in aligning allocations if we need to COW to actually
  	 * write to them.
  	 */
  	if (xfs_is_always_cow_inode(ip))
  		return 0;
  	if ((ip->i_d.di_flags & XFS_DIFLAG_EXTSIZE) && ip->i_d.di_extsize)
  		return ip->i_d.di_extsize;
  	if (XFS_IS_REALTIME_INODE(ip))
  		return ip->i_mount->m_sb.sb_rextsize;
  	return 0;
  }
  
  /*
   * Helper function to extract CoW extent size hint from inode.
   * Between the extent size hint and the CoW extent size hint, we
   * return the greater of the two.  If the value is zero (automatic),
   * use the default size.
   */
  xfs_extlen_t
  xfs_get_cowextsz_hint(
  	struct xfs_inode	*ip)
  {
  	xfs_extlen_t		a, b;
  
  	a = 0;
  	if (ip->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE)
  		a = ip->i_d.di_cowextsize;
  	b = xfs_get_extsz_hint(ip);
  
  	a = max(a, b);
  	if (a == 0)
  		return XFS_DEFAULT_COWEXTSZ_HINT;
  	return a;
  }
  
  /*
   * These two are wrapper routines around the xfs_ilock() routine used to
   * centralize some grungy code.  They are used in places that wish to lock the
   * inode solely for reading the extents.  The reason these places can't just
   * call xfs_ilock(ip, XFS_ILOCK_SHARED) is that the inode lock also guards to
   * bringing in of the extents from disk for a file in b-tree format.  If the
   * inode is in b-tree format, then we need to lock the inode exclusively until
   * the extents are read in.  Locking it exclusively all the time would limit
   * our parallelism unnecessarily, though.  What we do instead is check to see
   * if the extents have been read in yet, and only lock the inode exclusively
   * if they have not.
   *
   * The functions return a value which should be given to the corresponding
   * xfs_iunlock() call.
   */
  uint
  xfs_ilock_data_map_shared(
  	struct xfs_inode	*ip)
  {
  	uint			lock_mode = XFS_ILOCK_SHARED;
  
  	if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE &&
  	    (ip->i_df.if_flags & XFS_IFEXTENTS) == 0)
  		lock_mode = XFS_ILOCK_EXCL;
  	xfs_ilock(ip, lock_mode);
  	return lock_mode;
  }
  
  uint
  xfs_ilock_attr_map_shared(
  	struct xfs_inode	*ip)
  {
  	uint			lock_mode = XFS_ILOCK_SHARED;
  
  	if (ip->i_d.di_aformat == XFS_DINODE_FMT_BTREE &&
  	    (ip->i_afp->if_flags & XFS_IFEXTENTS) == 0)
  		lock_mode = XFS_ILOCK_EXCL;
  	xfs_ilock(ip, lock_mode);
  	return lock_mode;
  }
  
  /*
   * In addition to i_rwsem in the VFS inode, the xfs inode contains 2
   * multi-reader locks: i_mmap_lock and the i_lock.  This routine allows
   * various combinations of the locks to be obtained.
   *
   * The 3 locks should always be ordered so that the IO lock is obtained first,
   * the mmap lock second and the ilock last in order to prevent deadlock.
   *
   * Basic locking order:
   *
   * i_rwsem -> i_mmap_lock -> page_lock -> i_ilock
   *
   * mmap_sem locking order:
   *
   * i_rwsem -> page lock -> mmap_sem
   * mmap_sem -> i_mmap_lock -> page_lock
   *
   * The difference in mmap_sem locking order mean that we cannot hold the
   * i_mmap_lock over syscall based read(2)/write(2) based IO. These IO paths can
   * fault in pages during copy in/out (for buffered IO) or require the mmap_sem
   * in get_user_pages() to map the user pages into the kernel address space for
   * direct IO. Similarly the i_rwsem cannot be taken inside a page fault because
   * page faults already hold the mmap_sem.
   *
   * Hence to serialise fully against both syscall and mmap based IO, we need to
   * take both the i_rwsem and the i_mmap_lock. These locks should *only* be both
   * taken in places where we need to invalidate the page cache in a race
   * free manner (e.g. truncate, hole punch and other extent manipulation
   * functions).
   */
  void
  xfs_ilock(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	trace_xfs_ilock(ip, lock_flags, _RET_IP_);
  
  	/*
  	 * You can't set both SHARED and EXCL for the same lock,
  	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
  	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
  	 */
  	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
  	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL)) !=
  	       (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
  	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
  
  	if (lock_flags & XFS_IOLOCK_EXCL) {
  		down_write_nested(&VFS_I(ip)->i_rwsem,
  				  XFS_IOLOCK_DEP(lock_flags));
  	} else if (lock_flags & XFS_IOLOCK_SHARED) {
  		down_read_nested(&VFS_I(ip)->i_rwsem,
  				 XFS_IOLOCK_DEP(lock_flags));
  	}
  
  	if (lock_flags & XFS_MMAPLOCK_EXCL)
  		mrupdate_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
  	else if (lock_flags & XFS_MMAPLOCK_SHARED)
  		mraccess_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
  
  	if (lock_flags & XFS_ILOCK_EXCL)
  		mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
  	else if (lock_flags & XFS_ILOCK_SHARED)
  		mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
  }
  
  /*
   * This is just like xfs_ilock(), except that the caller
   * is guaranteed not to sleep.  It returns 1 if it gets
   * the requested locks and 0 otherwise.  If the IO lock is
   * obtained but the inode lock cannot be, then the IO lock
   * is dropped before returning.
   *
   * ip -- the inode being locked
   * lock_flags -- this parameter indicates the inode's locks to be
   *       to be locked.  See the comment for xfs_ilock() for a list
   *	 of valid values.
   */
  int
  xfs_ilock_nowait(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	trace_xfs_ilock_nowait(ip, lock_flags, _RET_IP_);
  
  	/*
  	 * You can't set both SHARED and EXCL for the same lock,
  	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
  	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
  	 */
  	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
  	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL)) !=
  	       (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
  	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
  
  	if (lock_flags & XFS_IOLOCK_EXCL) {
  		if (!down_write_trylock(&VFS_I(ip)->i_rwsem))
  			goto out;
  	} else if (lock_flags & XFS_IOLOCK_SHARED) {
  		if (!down_read_trylock(&VFS_I(ip)->i_rwsem))
  			goto out;
  	}
  
  	if (lock_flags & XFS_MMAPLOCK_EXCL) {
  		if (!mrtryupdate(&ip->i_mmaplock))
  			goto out_undo_iolock;
  	} else if (lock_flags & XFS_MMAPLOCK_SHARED) {
  		if (!mrtryaccess(&ip->i_mmaplock))
  			goto out_undo_iolock;
  	}
  
  	if (lock_flags & XFS_ILOCK_EXCL) {
  		if (!mrtryupdate(&ip->i_lock))
  			goto out_undo_mmaplock;
  	} else if (lock_flags & XFS_ILOCK_SHARED) {
  		if (!mrtryaccess(&ip->i_lock))
  			goto out_undo_mmaplock;
  	}
  	return 1;
  
  out_undo_mmaplock:
  	if (lock_flags & XFS_MMAPLOCK_EXCL)
  		mrunlock_excl(&ip->i_mmaplock);
  	else if (lock_flags & XFS_MMAPLOCK_SHARED)
  		mrunlock_shared(&ip->i_mmaplock);
  out_undo_iolock:
  	if (lock_flags & XFS_IOLOCK_EXCL)
  		up_write(&VFS_I(ip)->i_rwsem);
  	else if (lock_flags & XFS_IOLOCK_SHARED)
  		up_read(&VFS_I(ip)->i_rwsem);
  out:
  	return 0;
  }
  
  /*
   * xfs_iunlock() is used to drop the inode locks acquired with
   * xfs_ilock() and xfs_ilock_nowait().  The caller must pass
   * in the flags given to xfs_ilock() or xfs_ilock_nowait() so
   * that we know which locks to drop.
   *
   * ip -- the inode being unlocked
   * lock_flags -- this parameter indicates the inode's locks to be
   *       to be unlocked.  See the comment for xfs_ilock() for a list
   *	 of valid values for this parameter.
   *
   */
  void
  xfs_iunlock(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	/*
  	 * You can't set both SHARED and EXCL for the same lock,
  	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
  	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
  	 */
  	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
  	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL)) !=
  	       (XFS_MMAPLOCK_SHARED | XFS_MMAPLOCK_EXCL));
  	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
  	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
  	ASSERT(lock_flags != 0);
  
  	if (lock_flags & XFS_IOLOCK_EXCL)
  		up_write(&VFS_I(ip)->i_rwsem);
  	else if (lock_flags & XFS_IOLOCK_SHARED)
  		up_read(&VFS_I(ip)->i_rwsem);
  
  	if (lock_flags & XFS_MMAPLOCK_EXCL)
  		mrunlock_excl(&ip->i_mmaplock);
  	else if (lock_flags & XFS_MMAPLOCK_SHARED)
  		mrunlock_shared(&ip->i_mmaplock);
  
  	if (lock_flags & XFS_ILOCK_EXCL)
  		mrunlock_excl(&ip->i_lock);
  	else if (lock_flags & XFS_ILOCK_SHARED)
  		mrunlock_shared(&ip->i_lock);
  
  	trace_xfs_iunlock(ip, lock_flags, _RET_IP_);
  }
  
  /*
   * give up write locks.  the i/o lock cannot be held nested
   * if it is being demoted.
   */
  void
  xfs_ilock_demote(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL));
  	ASSERT((lock_flags &
  		~(XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
  
  	if (lock_flags & XFS_ILOCK_EXCL)
  		mrdemote(&ip->i_lock);
  	if (lock_flags & XFS_MMAPLOCK_EXCL)
  		mrdemote(&ip->i_mmaplock);
  	if (lock_flags & XFS_IOLOCK_EXCL)
  		downgrade_write(&VFS_I(ip)->i_rwsem);
  
  	trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
  }
  
  #if defined(DEBUG) || defined(XFS_WARN)
  int
  xfs_isilocked(
  	xfs_inode_t		*ip,
  	uint			lock_flags)
  {
  	if (lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) {
  		if (!(lock_flags & XFS_ILOCK_SHARED))
  			return !!ip->i_lock.mr_writer;
  		return rwsem_is_locked(&ip->i_lock.mr_lock);
  	}
  
  	if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
  		if (!(lock_flags & XFS_MMAPLOCK_SHARED))
  			return !!ip->i_mmaplock.mr_writer;
  		return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
  	}
  
  	if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
  		if (!(lock_flags & XFS_IOLOCK_SHARED))
  			return !debug_locks ||
  				lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0);
  		return rwsem_is_locked(&VFS_I(ip)->i_rwsem);
  	}
  
  	ASSERT(0);
  	return 0;
  }
  #endif
  
  /*
   * xfs_lockdep_subclass_ok() is only used in an ASSERT, so is only called when
   * DEBUG or XFS_WARN is set. And MAX_LOCKDEP_SUBCLASSES is then only defined
   * when CONFIG_LOCKDEP is set. Hence the complex define below to avoid build
   * errors and warnings.
   */
  #if (defined(DEBUG) || defined(XFS_WARN)) && defined(CONFIG_LOCKDEP)
  static bool
  xfs_lockdep_subclass_ok(
  	int subclass)
  {
  	return subclass < MAX_LOCKDEP_SUBCLASSES;
  }
  #else
  #define xfs_lockdep_subclass_ok(subclass)	(true)
  #endif
  
  /*
   * Bump the subclass so xfs_lock_inodes() acquires each lock with a different
   * value. This can be called for any type of inode lock combination, including
   * parent locking. Care must be taken to ensure we don't overrun the subclass
   * storage fields in the class mask we build.
   */
  static inline int
  xfs_lock_inumorder(int lock_mode, int subclass)
  {
  	int	class = 0;
  
  	ASSERT(!(lock_mode & (XFS_ILOCK_PARENT | XFS_ILOCK_RTBITMAP |
  			      XFS_ILOCK_RTSUM)));
  	ASSERT(xfs_lockdep_subclass_ok(subclass));
  
  	if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)) {
  		ASSERT(subclass <= XFS_IOLOCK_MAX_SUBCLASS);
  		class += subclass << XFS_IOLOCK_SHIFT;
  	}
  
  	if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) {
  		ASSERT(subclass <= XFS_MMAPLOCK_MAX_SUBCLASS);
  		class += subclass << XFS_MMAPLOCK_SHIFT;
  	}
  
  	if (lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)) {
  		ASSERT(subclass <= XFS_ILOCK_MAX_SUBCLASS);
  		class += subclass << XFS_ILOCK_SHIFT;
  	}
  
  	return (lock_mode & ~XFS_LOCK_SUBCLASS_MASK) | class;
  }
  
  /*
   * The following routine will lock n inodes in exclusive mode.  We assume the
   * caller calls us with the inodes in i_ino order.
   *
   * We need to detect deadlock where an inode that we lock is in the AIL and we
   * start waiting for another inode that is locked by a thread in a long running
   * transaction (such as truncate). This can result in deadlock since the long
   * running trans might need to wait for the inode we just locked in order to
   * push the tail and free space in the log.
   *
   * xfs_lock_inodes() can only be used to lock one type of lock at a time -
   * the iolock, the mmaplock or the ilock, but not more than one at a time. If we
   * lock more than one at a time, lockdep will report false positives saying we
   * have violated locking orders.
   */
  static void
  xfs_lock_inodes(
  	struct xfs_inode	**ips,
  	int			inodes,
  	uint			lock_mode)
  {
  	int			attempts = 0, i, j, try_lock;
  	struct xfs_log_item	*lp;
  
  	/*
  	 * Currently supports between 2 and 5 inodes with exclusive locking.  We
  	 * support an arbitrary depth of locking here, but absolute limits on
  	 * inodes depend on the the type of locking and the limits placed by
  	 * lockdep annotations in xfs_lock_inumorder.  These are all checked by
  	 * the asserts.
  	 */
  	ASSERT(ips && inodes >= 2 && inodes <= 5);
  	ASSERT(lock_mode & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL |
  			    XFS_ILOCK_EXCL));
  	ASSERT(!(lock_mode & (XFS_IOLOCK_SHARED | XFS_MMAPLOCK_SHARED |
  			      XFS_ILOCK_SHARED)));
  	ASSERT(!(lock_mode & XFS_MMAPLOCK_EXCL) ||
  		inodes <= XFS_MMAPLOCK_MAX_SUBCLASS + 1);
  	ASSERT(!(lock_mode & XFS_ILOCK_EXCL) ||
  		inodes <= XFS_ILOCK_MAX_SUBCLASS + 1);
  
  	if (lock_mode & XFS_IOLOCK_EXCL) {
  		ASSERT(!(lock_mode & (XFS_MMAPLOCK_EXCL | XFS_ILOCK_EXCL)));
  	} else if (lock_mode & XFS_MMAPLOCK_EXCL)
  		ASSERT(!(lock_mode & XFS_ILOCK_EXCL));
  
  	try_lock = 0;
  	i = 0;
  again:
  	for (; i < inodes; i++) {
  		ASSERT(ips[i]);
  
  		if (i && (ips[i] == ips[i - 1]))	/* Already locked */
  			continue;
  
  		/*
  		 * If try_lock is not set yet, make sure all locked inodes are
  		 * not in the AIL.  If any are, set try_lock to be used later.
  		 */
  		if (!try_lock) {
  			for (j = (i - 1); j >= 0 && !try_lock; j--) {
  				lp = &ips[j]->i_itemp->ili_item;
  				if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags))
  					try_lock++;
  			}
  		}
  
  		/*
  		 * If any of the previous locks we have locked is in the AIL,
  		 * we must TRY to get the second and subsequent locks. If
  		 * we can't get any, we must release all we have
  		 * and try again.
  		 */
  		if (!try_lock) {
  			xfs_ilock(ips[i], xfs_lock_inumorder(lock_mode, i));
  			continue;
  		}
  
  		/* try_lock means we have an inode locked that is in the AIL. */
  		ASSERT(i != 0);
  		if (xfs_ilock_nowait(ips[i], xfs_lock_inumorder(lock_mode, i)))
  			continue;
  
  		/*
  		 * Unlock all previous guys and try again.  xfs_iunlock will try
  		 * to push the tail if the inode is in the AIL.
  		 */
  		attempts++;
  		for (j = i - 1; j >= 0; j--) {
  			/*
  			 * Check to see if we've already unlocked this one.  Not
  			 * the first one going back, and the inode ptr is the
  			 * same.
  			 */
  			if (j != (i - 1) && ips[j] == ips[j + 1])
  				continue;
  
  			xfs_iunlock(ips[j], lock_mode);
  		}
  
  		if ((attempts % 5) == 0) {
  			delay(1); /* Don't just spin the CPU */
  		}
  		i = 0;
  		try_lock = 0;
  		goto again;
  	}
  }
  
  /*
   * xfs_lock_two_inodes() can only be used to lock one type of lock at a time -
   * the mmaplock or the ilock, but not more than one type at a time. If we lock
   * more than one at a time, lockdep will report false positives saying we have
   * violated locking orders.  The iolock must be double-locked separately since
   * we use i_rwsem for that.  We now support taking one lock EXCL and the other
   * SHARED.
   */
  void
  xfs_lock_two_inodes(
  	struct xfs_inode	*ip0,
  	uint			ip0_mode,
  	struct xfs_inode	*ip1,
  	uint			ip1_mode)
  {
  	struct xfs_inode	*temp;
  	uint			mode_temp;
  	int			attempts = 0;
  	struct xfs_log_item	*lp;
  
  	ASSERT(hweight32(ip0_mode) == 1);
  	ASSERT(hweight32(ip1_mode) == 1);
  	ASSERT(!(ip0_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
  	ASSERT(!(ip1_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
  	ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
  	       !(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
  	ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
  	       !(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
  	ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
  	       !(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
  	ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
  	       !(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
  
  	ASSERT(ip0->i_ino != ip1->i_ino);
  
  	if (ip0->i_ino > ip1->i_ino) {
  		temp = ip0;
  		ip0 = ip1;
  		ip1 = temp;
  		mode_temp = ip0_mode;
  		ip0_mode = ip1_mode;
  		ip1_mode = mode_temp;
  	}
  
   again:
  	xfs_ilock(ip0, xfs_lock_inumorder(ip0_mode, 0));
  
  	/*
  	 * If the first lock we have locked is in the AIL, we must TRY to get
  	 * the second lock. If we can't get it, we must release the first one
  	 * and try again.
  	 */
  	lp = &ip0->i_itemp->ili_item;
  	if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) {
  		if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(ip1_mode, 1))) {
  			xfs_iunlock(ip0, ip0_mode);
  			if ((++attempts % 5) == 0)
  				delay(1); /* Don't just spin the CPU */
  			goto again;
  		}
  	} else {
  		xfs_ilock(ip1, xfs_lock_inumorder(ip1_mode, 1));
  	}
  }
  
  void
  __xfs_iflock(
  	struct xfs_inode	*ip)
  {
  	wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IFLOCK_BIT);
  	DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IFLOCK_BIT);
  
  	do {
  		prepare_to_wait_exclusive(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
  		if (xfs_isiflocked(ip))
  			io_schedule();
  	} while (!xfs_iflock_nowait(ip));
  
  	finish_wait(wq, &wait.wq_entry);
  }
  
  STATIC uint
  _xfs_dic2xflags(
  	uint16_t		di_flags,
  	uint64_t		di_flags2,
  	bool			has_attr)
  {
  	uint			flags = 0;
  
  	if (di_flags & XFS_DIFLAG_ANY) {
  		if (di_flags & XFS_DIFLAG_REALTIME)
  			flags |= FS_XFLAG_REALTIME;
  		if (di_flags & XFS_DIFLAG_PREALLOC)
  			flags |= FS_XFLAG_PREALLOC;
  		if (di_flags & XFS_DIFLAG_IMMUTABLE)
  			flags |= FS_XFLAG_IMMUTABLE;
  		if (di_flags & XFS_DIFLAG_APPEND)
  			flags |= FS_XFLAG_APPEND;
  		if (di_flags & XFS_DIFLAG_SYNC)
  			flags |= FS_XFLAG_SYNC;
  		if (di_flags & XFS_DIFLAG_NOATIME)
  			flags |= FS_XFLAG_NOATIME;
  		if (di_flags & XFS_DIFLAG_NODUMP)
  			flags |= FS_XFLAG_NODUMP;
  		if (di_flags & XFS_DIFLAG_RTINHERIT)
  			flags |= FS_XFLAG_RTINHERIT;
  		if (di_flags & XFS_DIFLAG_PROJINHERIT)
  			flags |= FS_XFLAG_PROJINHERIT;
  		if (di_flags & XFS_DIFLAG_NOSYMLINKS)
  			flags |= FS_XFLAG_NOSYMLINKS;
  		if (di_flags & XFS_DIFLAG_EXTSIZE)
  			flags |= FS_XFLAG_EXTSIZE;
  		if (di_flags & XFS_DIFLAG_EXTSZINHERIT)
  			flags |= FS_XFLAG_EXTSZINHERIT;
  		if (di_flags & XFS_DIFLAG_NODEFRAG)
  			flags |= FS_XFLAG_NODEFRAG;
  		if (di_flags & XFS_DIFLAG_FILESTREAM)
  			flags |= FS_XFLAG_FILESTREAM;
  	}
  
  	if (di_flags2 & XFS_DIFLAG2_ANY) {
  		if (di_flags2 & XFS_DIFLAG2_DAX)
  			flags |= FS_XFLAG_DAX;
  		if (di_flags2 & XFS_DIFLAG2_COWEXTSIZE)
  			flags |= FS_XFLAG_COWEXTSIZE;
  	}
  
  	if (has_attr)
  		flags |= FS_XFLAG_HASATTR;
  
  	return flags;
  }
  
  uint
  xfs_ip2xflags(
  	struct xfs_inode	*ip)
  {
  	struct xfs_icdinode	*dic = &ip->i_d;
  
  	return _xfs_dic2xflags(dic->di_flags, dic->di_flags2, XFS_IFORK_Q(ip));
  }
  
  /*
   * Lookups up an inode from "name". If ci_name is not NULL, then a CI match
   * is allowed, otherwise it has to be an exact match. If a CI match is found,
   * ci_name->name will point to a the actual name (caller must free) or
   * will be set to NULL if an exact match is found.
   */
  int
  xfs_lookup(
  	xfs_inode_t		*dp,
  	struct xfs_name		*name,
  	xfs_inode_t		**ipp,
  	struct xfs_name		*ci_name)
  {
  	xfs_ino_t		inum;
  	int			error;
  
  	trace_xfs_lookup(dp, name);
  
  	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
  		return -EIO;
  
  	error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
  	if (error)
  		goto out_unlock;
  
  	error = xfs_iget(dp->i_mount, NULL, inum, 0, 0, ipp);
  	if (error)
  		goto out_free_name;
  
  	return 0;
  
  out_free_name:
  	if (ci_name)
  		kmem_free(ci_name->name);
  out_unlock:
  	*ipp = NULL;
  	return error;
  }
  
  /*
   * Allocate an inode on disk and return a copy of its in-core version.
   * The in-core inode is locked exclusively.  Set mode, nlink, and rdev
   * appropriately within the inode.  The uid and gid for the inode are
   * set according to the contents of the given cred structure.
   *
   * Use xfs_dialloc() to allocate the on-disk inode. If xfs_dialloc()
   * has a free inode available, call xfs_iget() to obtain the in-core
   * version of the allocated inode.  Finally, fill in the inode and
   * log its initial contents.  In this case, ialloc_context would be
   * set to NULL.
   *
   * If xfs_dialloc() does not have an available inode, it will replenish
   * its supply by doing an allocation. Since we can only do one
   * allocation within a transaction without deadlocks, we must commit
   * the current transaction before returning the inode itself.
   * In this case, therefore, we will set ialloc_context and return.
   * The caller should then commit the current transaction, start a new
   * transaction, and call xfs_ialloc() again to actually get the inode.
   *
   * To ensure that some other process does not grab the inode that
   * was allocated during the first call to xfs_ialloc(), this routine
   * also returns the [locked] bp pointing to the head of the freelist
   * as ialloc_context.  The caller should hold this buffer across
   * the commit and pass it back into this routine on the second call.
   *
   * If we are allocating quota inodes, we do not have a parent inode
   * to attach to or associate with (i.e. pip == NULL) because they
   * are not linked into the directory structure - they are attached
   * directly to the superblock - and so have no parent.
   */
  static int
  xfs_ialloc(
  	xfs_trans_t	*tp,
  	xfs_inode_t	*pip,
  	umode_t		mode,
  	xfs_nlink_t	nlink,
  	dev_t		rdev,
  	prid_t		prid,
  	xfs_buf_t	**ialloc_context,
  	xfs_inode_t	**ipp)
  {
  	struct xfs_mount *mp = tp->t_mountp;
  	xfs_ino_t	ino;
  	xfs_inode_t	*ip;
  	uint		flags;
  	int		error;
  	struct timespec64 tv;
  	struct inode	*inode;
  
  	/*
  	 * Call the space management code to pick
  	 * the on-disk inode to be allocated.
  	 */
  	error = xfs_dialloc(tp, pip ? pip->i_ino : 0, mode,
  			    ialloc_context, &ino);
  	if (error)
  		return error;
  	if (*ialloc_context || ino == NULLFSINO) {
  		*ipp = NULL;
  		return 0;
  	}
  	ASSERT(*ialloc_context == NULL);
  
  	/*
  	 * Protect against obviously corrupt allocation btree records. Later
  	 * xfs_iget checks will catch re-allocation of other active in-memory
  	 * and on-disk inodes. If we don't catch reallocating the parent inode
  	 * here we will deadlock in xfs_iget() so we have to do these checks
  	 * first.
  	 */
  	if ((pip && ino == pip->i_ino) || !xfs_verify_dir_ino(mp, ino)) {
  		xfs_alert(mp, "Allocated a known in-use inode 0x%llx!", ino);
  		return -EFSCORRUPTED;
  	}
  
  	/*
  	 * Get the in-core inode with the lock held exclusively.
  	 * This is because we're setting fields here we need
  	 * to prevent others from looking at until we're done.
  	 */
  	error = xfs_iget(mp, tp, ino, XFS_IGET_CREATE,
  			 XFS_ILOCK_EXCL, &ip);
  	if (error)
  		return error;
  	ASSERT(ip != NULL);
  	inode = VFS_I(ip);
  	inode->i_mode = mode;
  	set_nlink(inode, nlink);
  	inode->i_uid = current_fsuid();
  	inode->i_rdev = rdev;
  	ip->i_d.di_projid = prid;
  
  	if (pip && XFS_INHERIT_GID(pip)) {
  		inode->i_gid = VFS_I(pip)->i_gid;
  		if ((VFS_I(pip)->i_mode & S_ISGID) && S_ISDIR(mode))
  			inode->i_mode |= S_ISGID;
  	} else {
  		inode->i_gid = current_fsgid();
  	}
  
  	/*
  	 * If the group ID of the new file does not match the effective group
  	 * ID or one of the supplementary group IDs, the S_ISGID bit is cleared
  	 * (and only if the irix_sgid_inherit compatibility variable is set).
  	 */
  	if (irix_sgid_inherit &&
  	    (inode->i_mode & S_ISGID) && !in_group_p(inode->i_gid))
  		inode->i_mode &= ~S_ISGID;
  
  	ip->i_d.di_size = 0;
  	ip->i_d.di_nextents = 0;
  	ASSERT(ip->i_d.di_nblocks == 0);
  
  	tv = current_time(inode);
  	inode->i_mtime = tv;
  	inode->i_atime = tv;
  	inode->i_ctime = tv;
  
  	ip->i_d.di_extsize = 0;
  	ip->i_d.di_dmevmask = 0;
  	ip->i_d.di_dmstate = 0;
  	ip->i_d.di_flags = 0;
  
  	if (xfs_sb_version_has_v3inode(&mp->m_sb)) {
  		inode_set_iversion(inode, 1);
  		ip->i_d.di_flags2 = 0;
  		ip->i_d.di_cowextsize = 0;
  		ip->i_d.di_crtime = tv;
  	}
  
  	flags = XFS_ILOG_CORE;
  	switch (mode & S_IFMT) {
  	case S_IFIFO:
  	case S_IFCHR:
  	case S_IFBLK:
  	case S_IFSOCK:
  		ip->i_d.di_format = XFS_DINODE_FMT_DEV;
  		ip->i_df.if_flags = 0;
  		flags |= XFS_ILOG_DEV;
  		break;
  	case S_IFREG:
  	case S_IFDIR:
  		if (pip && (pip->i_d.di_flags & XFS_DIFLAG_ANY)) {
  			uint		di_flags = 0;
  
  			if (S_ISDIR(mode)) {
  				if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
  					di_flags |= XFS_DIFLAG_RTINHERIT;
  				if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
  					di_flags |= XFS_DIFLAG_EXTSZINHERIT;
  					ip->i_d.di_extsize = pip->i_d.di_extsize;
  				}
  				if (pip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
  					di_flags |= XFS_DIFLAG_PROJINHERIT;
  			} else if (S_ISREG(mode)) {
  				if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
  					di_flags |= XFS_DIFLAG_REALTIME;
  				if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
  					di_flags |= XFS_DIFLAG_EXTSIZE;
  					ip->i_d.di_extsize = pip->i_d.di_extsize;
  				}
  			}
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NOATIME) &&
  			    xfs_inherit_noatime)
  				di_flags |= XFS_DIFLAG_NOATIME;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NODUMP) &&
  			    xfs_inherit_nodump)
  				di_flags |= XFS_DIFLAG_NODUMP;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_SYNC) &&
  			    xfs_inherit_sync)
  				di_flags |= XFS_DIFLAG_SYNC;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) &&
  			    xfs_inherit_nosymlinks)
  				di_flags |= XFS_DIFLAG_NOSYMLINKS;
  			if ((pip->i_d.di_flags & XFS_DIFLAG_NODEFRAG) &&
  			    xfs_inherit_nodefrag)
  				di_flags |= XFS_DIFLAG_NODEFRAG;
  			if (pip->i_d.di_flags & XFS_DIFLAG_FILESTREAM)
  				di_flags |= XFS_DIFLAG_FILESTREAM;
  
  			ip->i_d.di_flags |= di_flags;
  		}
  		if (pip && (pip->i_d.di_flags2 & XFS_DIFLAG2_ANY)) {
  			if (pip->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) {
  				ip->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
  				ip->i_d.di_cowextsize = pip->i_d.di_cowextsize;
  			}
  			if (pip->i_d.di_flags2 & XFS_DIFLAG2_DAX)
  				ip->i_d.di_flags2 |= XFS_DIFLAG2_DAX;
  		}
  		/* FALLTHROUGH */
  	case S_IFLNK:
  		ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
  		ip->i_df.if_flags = XFS_IFEXTENTS;
  		ip->i_df.if_bytes = 0;
  		ip->i_df.if_u1.if_root = NULL;
  		break;
  	default:
  		ASSERT(0);
  	}
  	/*
  	 * Attribute fork settings for new inode.
  	 */
  	ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
  	ip->i_d.di_anextents = 0;
  
  	/*
  	 * Log the new values stuffed into the inode.
  	 */
  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
  	xfs_trans_log_inode(tp, ip, flags);
  
  	/* now that we have an i_mode we can setup the inode structure */
  	xfs_setup_inode(ip);
  
  	*ipp = ip;
  	return 0;
  }
  
  /*
   * Allocates a new inode from disk and return a pointer to the
   * incore copy. This routine will internally commit the current
   * transaction and allocate a new one if the Space Manager needed
   * to do an allocation to replenish the inode free-list.
   *
   * This routine is designed to be called from xfs_create and
   * xfs_create_dir.
   *
   */
  int
  xfs_dir_ialloc(
  	xfs_trans_t	**tpp,		/* input: current transaction;
  					   output: may be a new transaction. */
  	xfs_inode_t	*dp,		/* directory within whose allocate
  					   the inode. */
  	umode_t		mode,
  	xfs_nlink_t	nlink,
  	dev_t		rdev,
  	prid_t		prid,		/* project id */
  	xfs_inode_t	**ipp)		/* pointer to inode; it will be
  					   locked. */
  {
  	xfs_trans_t	*tp;
  	xfs_inode_t	*ip;
  	xfs_buf_t	*ialloc_context = NULL;
  	int		code;
  	void		*dqinfo;
  	uint		tflags;
  
  	tp = *tpp;
  	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
  
  	/*
  	 * xfs_ialloc will return a pointer to an incore inode if
  	 * the Space Manager has an available inode on the free
  	 * list. Otherwise, it will do an allocation and replenish
  	 * the freelist.  Since we can only do one allocation per
  	 * transaction without deadlocks, we will need to commit the
  	 * current transaction and start a new one.  We will then
  	 * need to call xfs_ialloc again to get the inode.
  	 *
  	 * If xfs_ialloc did an allocation to replenish the freelist,
  	 * it returns the bp containing the head of the freelist as
  	 * ialloc_context. We will hold a lock on it across the
  	 * transaction commit so that no other process can steal
  	 * the inode(s) that we've just allocated.
  	 */
  	code = xfs_ialloc(tp, dp, mode, nlink, rdev, prid, &ialloc_context,
  			&ip);
  
  	/*
  	 * Return an error if we were unable to allocate a new inode.
  	 * This should only happen if we run out of space on disk or
  	 * encounter a disk error.
  	 */
  	if (code) {
  		*ipp = NULL;
  		return code;
  	}
  	if (!ialloc_context && !ip) {
  		*ipp = NULL;
  		return -ENOSPC;
  	}
  
  	/*
  	 * If the AGI buffer is non-NULL, then we were unable to get an
  	 * inode in one operation.  We need to commit the current
  	 * transaction and call xfs_ialloc() again.  It is guaranteed
  	 * to succeed the second time.
  	 */
  	if (ialloc_context) {
  		/*
  		 * Normally, xfs_trans_commit releases all the locks.
  		 * We call bhold to hang on to the ialloc_context across
  		 * the commit.  Holding this buffer prevents any other
  		 * processes from doing any allocations in this
  		 * allocation group.
  		 */
  		xfs_trans_bhold(tp, ialloc_context);
  
  		/*
  		 * We want the quota changes to be associated with the next
  		 * transaction, NOT this one. So, detach the dqinfo from this
  		 * and attach it to the next transaction.
  		 */
  		dqinfo = NULL;
  		tflags = 0;
  		if (tp->t_dqinfo) {
  			dqinfo = (void *)tp->t_dqinfo;
  			tp->t_dqinfo = NULL;
  			tflags = tp->t_flags & XFS_TRANS_DQ_DIRTY;
  			tp->t_flags &= ~(XFS_TRANS_DQ_DIRTY);
  		}
  
  		code = xfs_trans_roll(&tp);
  
  		/*
  		 * Re-attach the quota info that we detached from prev trx.
  		 */
  		if (dqinfo) {
  			tp->t_dqinfo = dqinfo;
  			tp->t_flags |= tflags;
  		}
  
  		if (code) {
  			xfs_buf_relse(ialloc_context);
  			*tpp = tp;
  			*ipp = NULL;
  			return code;
  		}
  		xfs_trans_bjoin(tp, ialloc_context);
  
  		/*
  		 * Call ialloc again. Since we've locked out all
  		 * other allocations in this allocation group,
  		 * this call should always succeed.
  		 */
  		code = xfs_ialloc(tp, dp, mode, nlink, rdev, prid,
  				  &ialloc_context, &ip);
  
  		/*
  		 * If we get an error at this point, return to the caller
  		 * so that the current transaction can be aborted.
  		 */
  		if (code) {
  			*tpp = tp;
  			*ipp = NULL;
  			return code;
  		}
  		ASSERT(!ialloc_context && ip);
  
  	}
  
  	*ipp = ip;
  	*tpp = tp;
  
  	return 0;
  }
  
  /*
   * Decrement the link count on an inode & log the change.  If this causes the
   * link count to go to zero, move the inode to AGI unlinked list so that it can
   * be freed when the last active reference goes away via xfs_inactive().
   */
  static int			/* error */
  xfs_droplink(
  	xfs_trans_t *tp,
  	xfs_inode_t *ip)
  {
  	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
  
  	drop_nlink(VFS_I(ip));
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	if (VFS_I(ip)->i_nlink)
  		return 0;
  
  	return xfs_iunlink(tp, ip);
  }
  
  /*
   * Increment the link count on an inode & log the change.
   */
  static void
  xfs_bumplink(
  	xfs_trans_t *tp,
  	xfs_inode_t *ip)
  {
  	xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG);
  
  	inc_nlink(VFS_I(ip));
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  }
  
  int
  xfs_create(
  	xfs_inode_t		*dp,
  	struct xfs_name		*name,
  	umode_t			mode,
  	dev_t			rdev,
  	xfs_inode_t		**ipp)
  {
  	int			is_dir = S_ISDIR(mode);
  	struct xfs_mount	*mp = dp->i_mount;
  	struct xfs_inode	*ip = NULL;
  	struct xfs_trans	*tp = NULL;
  	int			error;
  	bool                    unlock_dp_on_error = false;
  	prid_t			prid;
  	struct xfs_dquot	*udqp = NULL;
  	struct xfs_dquot	*gdqp = NULL;
  	struct xfs_dquot	*pdqp = NULL;
  	struct xfs_trans_res	*tres;
  	uint			resblks;
  
  	trace_xfs_create(dp, name);
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	prid = xfs_get_initial_prid(dp);
  
  	/*
  	 * Make sure that we have allocated dquot(s) on disk.
  	 */
  	error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
  					XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
  					&udqp, &gdqp, &pdqp);
  	if (error)
  		return error;
  
  	if (is_dir) {
  		resblks = XFS_MKDIR_SPACE_RES(mp, name->len);
  		tres = &M_RES(mp)->tr_mkdir;
  	} else {
  		resblks = XFS_CREATE_SPACE_RES(mp, name->len);
  		tres = &M_RES(mp)->tr_create;
  	}
  
  	/*
  	 * Initially assume that the file does not exist and
  	 * reserve the resources for that case.  If that is not
  	 * the case we'll drop the one we have and get a more
  	 * appropriate transaction later.
  	 */
  	error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
  	if (error == -ENOSPC) {
  		/* flush outstanding delalloc blocks and retry */
  		xfs_flush_inodes(mp);
  		error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
  	}
  	if (error)
  		goto out_release_inode;
  
  	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
  	unlock_dp_on_error = true;
  
  	/*
  	 * Reserve disk quota and the inode.
  	 */
  	error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
  						pdqp, resblks, 1, 0);
  	if (error)
  		goto out_trans_cancel;
  
  	/*
  	 * A newly created regular or special file just has one directory
  	 * entry pointing to them, but a directory also the "." entry
  	 * pointing to itself.
  	 */
  	error = xfs_dir_ialloc(&tp, dp, mode, is_dir ? 2 : 1, rdev, prid, &ip);
  	if (error)
  		goto out_trans_cancel;
  
  	/*
  	 * Now we join the directory inode to the transaction.  We do not do it
  	 * earlier because xfs_dir_ialloc might commit the previous transaction
  	 * (and release all the locks).  An error from here on will result in
  	 * the transaction cancel unlocking dp so don't do it explicitly in the
  	 * error path.
  	 */
  	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
  	unlock_dp_on_error = false;
  
  	error = xfs_dir_createname(tp, dp, name, ip->i_ino,
  					resblks - XFS_IALLOC_SPACE_RES(mp));
  	if (error) {
  		ASSERT(error != -ENOSPC);
  		goto out_trans_cancel;
  	}
  	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
  
  	if (is_dir) {
  		error = xfs_dir_init(tp, ip, dp);
  		if (error)
  			goto out_trans_cancel;
  
  		xfs_bumplink(tp, dp);
  	}
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * create transaction goes to disk before returning to
  	 * the user.
  	 */
  	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
  		xfs_trans_set_sync(tp);
  
  	/*
  	 * Attach the dquot(s) to the inodes and modify them incore.
  	 * These ids of the inode couldn't have changed since the new
  	 * inode has been locked ever since it was created.
  	 */
  	xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
  
  	error = xfs_trans_commit(tp);
  	if (error)
  		goto out_release_inode;
  
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  	xfs_qm_dqrele(pdqp);
  
  	*ipp = ip;
  	return 0;
  
   out_trans_cancel:
  	xfs_trans_cancel(tp);
   out_release_inode:
  	/*
  	 * Wait until after the current transaction is aborted to finish the
  	 * setup of the inode and release the inode.  This prevents recursive
  	 * transactions and deadlocks from xfs_inactive.
  	 */
  	if (ip) {
  		xfs_finish_inode_setup(ip);
  		xfs_irele(ip);
  	}
  
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  	xfs_qm_dqrele(pdqp);
  
  	if (unlock_dp_on_error)
  		xfs_iunlock(dp, XFS_ILOCK_EXCL);
  	return error;
  }
  
  int
  xfs_create_tmpfile(
  	struct xfs_inode	*dp,
  	umode_t			mode,
  	struct xfs_inode	**ipp)
  {
  	struct xfs_mount	*mp = dp->i_mount;
  	struct xfs_inode	*ip = NULL;
  	struct xfs_trans	*tp = NULL;
  	int			error;
  	prid_t                  prid;
  	struct xfs_dquot	*udqp = NULL;
  	struct xfs_dquot	*gdqp = NULL;
  	struct xfs_dquot	*pdqp = NULL;
  	struct xfs_trans_res	*tres;
  	uint			resblks;
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	prid = xfs_get_initial_prid(dp);
  
  	/*
  	 * Make sure that we have allocated dquot(s) on disk.
  	 */
  	error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
  				XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
  				&udqp, &gdqp, &pdqp);
  	if (error)
  		return error;
  
  	resblks = XFS_IALLOC_SPACE_RES(mp);
  	tres = &M_RES(mp)->tr_create_tmpfile;
  
  	error = xfs_trans_alloc(mp, tres, resblks, 0, 0, &tp);
  	if (error)
  		goto out_release_inode;
  
  	error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
  						pdqp, resblks, 1, 0);
  	if (error)
  		goto out_trans_cancel;
  
  	error = xfs_dir_ialloc(&tp, dp, mode, 0, 0, prid, &ip);
  	if (error)
  		goto out_trans_cancel;
  
  	if (mp->m_flags & XFS_MOUNT_WSYNC)
  		xfs_trans_set_sync(tp);
  
  	/*
  	 * Attach the dquot(s) to the inodes and modify them incore.
  	 * These ids of the inode couldn't have changed since the new
  	 * inode has been locked ever since it was created.
  	 */
  	xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
  
  	error = xfs_iunlink(tp, ip);
  	if (error)
  		goto out_trans_cancel;
  
  	error = xfs_trans_commit(tp);
  	if (error)
  		goto out_release_inode;
  
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  	xfs_qm_dqrele(pdqp);
  
  	*ipp = ip;
  	return 0;
  
   out_trans_cancel:
  	xfs_trans_cancel(tp);
   out_release_inode:
  	/*
  	 * Wait until after the current transaction is aborted to finish the
  	 * setup of the inode and release the inode.  This prevents recursive
  	 * transactions and deadlocks from xfs_inactive.
  	 */
  	if (ip) {
  		xfs_finish_inode_setup(ip);
  		xfs_irele(ip);
  	}
  
  	xfs_qm_dqrele(udqp);
  	xfs_qm_dqrele(gdqp);
  	xfs_qm_dqrele(pdqp);
  
  	return error;
  }
  
  int
  xfs_link(
  	xfs_inode_t		*tdp,
  	xfs_inode_t		*sip,
  	struct xfs_name		*target_name)
  {
  	xfs_mount_t		*mp = tdp->i_mount;
  	xfs_trans_t		*tp;
  	int			error;
  	int			resblks;
  
  	trace_xfs_link(tdp, target_name);
  
  	ASSERT(!S_ISDIR(VFS_I(sip)->i_mode));
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	error = xfs_qm_dqattach(sip);
  	if (error)
  		goto std_return;
  
  	error = xfs_qm_dqattach(tdp);
  	if (error)
  		goto std_return;
  
  	resblks = XFS_LINK_SPACE_RES(mp, target_name->len);
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_link, resblks, 0, 0, &tp);
  	if (error == -ENOSPC) {
  		resblks = 0;
  		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_link, 0, 0, 0, &tp);
  	}
  	if (error)
  		goto std_return;
  
  	xfs_lock_two_inodes(sip, XFS_ILOCK_EXCL, tdp, XFS_ILOCK_EXCL);
  
  	xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);
  
  	/*
  	 * If we are using project inheritance, we only allow hard link
  	 * creation in our tree when the project IDs are the same; else
  	 * the tree quota mechanism could be circumvented.
  	 */
  	if (unlikely((tdp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
  		     tdp->i_d.di_projid != sip->i_d.di_projid)) {
  		error = -EXDEV;
  		goto error_return;
  	}
  
  	if (!resblks) {
  		error = xfs_dir_canenter(tp, tdp, target_name);
  		if (error)
  			goto error_return;
  	}
  
  	/*
  	 * Handle initial link state of O_TMPFILE inode
  	 */
  	if (VFS_I(sip)->i_nlink == 0) {
  		error = xfs_iunlink_remove(tp, sip);
  		if (error)
  			goto error_return;
  	}
  
  	error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
  				   resblks);
  	if (error)
  		goto error_return;
  	xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);
  
  	xfs_bumplink(tp, sip);
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * link transaction goes to disk before returning to
  	 * the user.
  	 */
  	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
  		xfs_trans_set_sync(tp);
  
  	return xfs_trans_commit(tp);
  
   error_return:
  	xfs_trans_cancel(tp);
   std_return:
  	return error;
  }
  
  /* Clear the reflink flag and the cowblocks tag if possible. */
  static void
  xfs_itruncate_clear_reflink_flags(
  	struct xfs_inode	*ip)
  {
  	struct xfs_ifork	*dfork;
  	struct xfs_ifork	*cfork;
  
  	if (!xfs_is_reflink_inode(ip))
  		return;
  	dfork = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
  	cfork = XFS_IFORK_PTR(ip, XFS_COW_FORK);
  	if (dfork->if_bytes == 0 && cfork->if_bytes == 0)
  		ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
  	if (cfork->if_bytes == 0)
  		xfs_inode_clear_cowblocks_tag(ip);
  }
  
  /*
   * Free up the underlying blocks past new_size.  The new size must be smaller
   * than the current size.  This routine can be used both for the attribute and
   * data fork, and does not modify the inode size, which is left to the caller.
   *
   * The transaction passed to this routine must have made a permanent log
   * reservation of at least XFS_ITRUNCATE_LOG_RES.  This routine may commit the
   * given transaction and start new ones, so make sure everything involved in
   * the transaction is tidy before calling here.  Some transaction will be
   * returned to the caller to be committed.  The incoming transaction must
   * already include the inode, and both inode locks must be held exclusively.
   * The inode must also be "held" within the transaction.  On return the inode
   * will be "held" within the returned transaction.  This routine does NOT
   * require any disk space to be reserved for it within the transaction.
   *
   * If we get an error, we must return with the inode locked and linked into the
   * current transaction. This keeps things simple for the higher level code,
   * because it always knows that the inode is locked and held in the transaction
   * that returns to it whether errors occur or not.  We don't mark the inode
   * dirty on error so that transactions can be easily aborted if possible.
   */
  int
  xfs_itruncate_extents_flags(
  	struct xfs_trans	**tpp,
  	struct xfs_inode	*ip,
  	int			whichfork,
  	xfs_fsize_t		new_size,
  	int			flags)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_trans	*tp = *tpp;
  	xfs_fileoff_t		first_unmap_block;
  	xfs_filblks_t		unmap_len;
  	int			error = 0;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(!atomic_read(&VFS_I(ip)->i_count) ||
  	       xfs_isilocked(ip, XFS_IOLOCK_EXCL));
  	ASSERT(new_size <= XFS_ISIZE(ip));
  	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
  	ASSERT(ip->i_itemp != NULL);
  	ASSERT(ip->i_itemp->ili_lock_flags == 0);
  	ASSERT(!XFS_NOT_DQATTACHED(mp, ip));
  
  	trace_xfs_itruncate_extents_start(ip, new_size);
  
  	flags |= xfs_bmapi_aflag(whichfork);
  
  	/*
  	 * Since it is possible for space to become allocated beyond
  	 * the end of the file (in a crash where the space is allocated
  	 * but the inode size is not yet updated), simply remove any
  	 * blocks which show up between the new EOF and the maximum
  	 * possible file size.
  	 *
  	 * We have to free all the blocks to the bmbt maximum offset, even if
  	 * the page cache can't scale that far.
  	 */
  	first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
  	if (first_unmap_block >= XFS_MAX_FILEOFF) {
  		WARN_ON_ONCE(first_unmap_block > XFS_MAX_FILEOFF);
  		return 0;
  	}
  
  	unmap_len = XFS_MAX_FILEOFF - first_unmap_block + 1;
  	while (unmap_len > 0) {
  		ASSERT(tp->t_firstblock == NULLFSBLOCK);
  		error = __xfs_bunmapi(tp, ip, first_unmap_block, &unmap_len,
  				flags, XFS_ITRUNC_MAX_EXTENTS);
  		if (error)
  			goto out;
  
  		/*
  		 * Duplicate the transaction that has the permanent
  		 * reservation and commit the old transaction.
  		 */
  		error = xfs_defer_finish(&tp);
  		if (error)
  			goto out;
  
  		error = xfs_trans_roll_inode(&tp, ip);
  		if (error)
  			goto out;
  	}
  
  	if (whichfork == XFS_DATA_FORK) {
  		/* Remove all pending CoW reservations. */
  		error = xfs_reflink_cancel_cow_blocks(ip, &tp,
  				first_unmap_block, XFS_MAX_FILEOFF, true);
  		if (error)
  			goto out;
  
  		xfs_itruncate_clear_reflink_flags(ip);
  	}
  
  	/*
  	 * Always re-log the inode so that our permanent transaction can keep
  	 * on rolling it forward in the log.
  	 */
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	trace_xfs_itruncate_extents_end(ip, new_size);
  
  out:
  	*tpp = tp;
  	return error;
  }
  
  int
  xfs_release(
  	xfs_inode_t	*ip)
  {
  	xfs_mount_t	*mp = ip->i_mount;
  	int		error;
  
  	if (!S_ISREG(VFS_I(ip)->i_mode) || (VFS_I(ip)->i_mode == 0))
  		return 0;
  
  	/* If this is a read-only mount, don't do this (would generate I/O) */
  	if (mp->m_flags & XFS_MOUNT_RDONLY)
  		return 0;
  
  	if (!XFS_FORCED_SHUTDOWN(mp)) {
  		int truncated;
  
  		/*
  		 * If we previously truncated this file and removed old data
  		 * in the process, we want to initiate "early" writeout on
  		 * the last close.  This is an attempt to combat the notorious
  		 * NULL files problem which is particularly noticeable from a
  		 * truncate down, buffered (re-)write (delalloc), followed by
  		 * a crash.  What we are effectively doing here is
  		 * significantly reducing the time window where we'd otherwise
  		 * be exposed to that problem.
  		 */
  		truncated = xfs_iflags_test_and_clear(ip, XFS_ITRUNCATED);
  		if (truncated) {
  			xfs_iflags_clear(ip, XFS_IDIRTY_RELEASE);
  			if (ip->i_delayed_blks > 0) {
  				error = filemap_flush(VFS_I(ip)->i_mapping);
  				if (error)
  					return error;
  			}
  		}
  	}
  
  	if (VFS_I(ip)->i_nlink == 0)
  		return 0;
  
  	if (xfs_can_free_eofblocks(ip, false)) {
  
  		/*
  		 * Check if the inode is being opened, written and closed
  		 * frequently and we have delayed allocation blocks outstanding
  		 * (e.g. streaming writes from the NFS server), truncating the
  		 * blocks past EOF will cause fragmentation to occur.
  		 *
  		 * In this case don't do the truncation, but we have to be
  		 * careful how we detect this case. Blocks beyond EOF show up as
  		 * i_delayed_blks even when the inode is clean, so we need to
  		 * truncate them away first before checking for a dirty release.
  		 * Hence on the first dirty close we will still remove the
  		 * speculative allocation, but after that we will leave it in
  		 * place.
  		 */
  		if (xfs_iflags_test(ip, XFS_IDIRTY_RELEASE))
  			return 0;
  		/*
  		 * If we can't get the iolock just skip truncating the blocks
  		 * past EOF because we could deadlock with the mmap_sem
  		 * otherwise. We'll get another chance to drop them once the
  		 * last reference to the inode is dropped, so we'll never leak
  		 * blocks permanently.
  		 */
  		if (xfs_ilock_nowait(ip, XFS_IOLOCK_EXCL)) {
  			error = xfs_free_eofblocks(ip);
  			xfs_iunlock(ip, XFS_IOLOCK_EXCL);
  			if (error)
  				return error;
  		}
  
  		/* delalloc blocks after truncation means it really is dirty */
  		if (ip->i_delayed_blks)
  			xfs_iflags_set(ip, XFS_IDIRTY_RELEASE);
  	}
  	return 0;
  }
  
  /*
   * xfs_inactive_truncate
   *
   * Called to perform a truncate when an inode becomes unlinked.
   */
  STATIC int
  xfs_inactive_truncate(
  	struct xfs_inode *ip)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_trans	*tp;
  	int			error;
  
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
  	if (error) {
  		ASSERT(XFS_FORCED_SHUTDOWN(mp));
  		return error;
  	}
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, 0);
  
  	/*
  	 * Log the inode size first to prevent stale data exposure in the event
  	 * of a system crash before the truncate completes. See the related
  	 * comment in xfs_vn_setattr_size() for details.
  	 */
  	ip->i_d.di_size = 0;
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK, 0);
  	if (error)
  		goto error_trans_cancel;
  
  	ASSERT(ip->i_d.di_nextents == 0);
  
  	error = xfs_trans_commit(tp);
  	if (error)
  		goto error_unlock;
  
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return 0;
  
  error_trans_cancel:
  	xfs_trans_cancel(tp);
  error_unlock:
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return error;
  }
  
  /*
   * xfs_inactive_ifree()
   *
   * Perform the inode free when an inode is unlinked.
   */
  STATIC int
  xfs_inactive_ifree(
  	struct xfs_inode *ip)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_trans	*tp;
  	int			error;
  
  	/*
  	 * We try to use a per-AG reservation for any block needed by the finobt
  	 * tree, but as the finobt feature predates the per-AG reservation
  	 * support a degraded file system might not have enough space for the
  	 * reservation at mount time.  In that case try to dip into the reserved
  	 * pool and pray.
  	 *
  	 * Send a warning if the reservation does happen to fail, as the inode
  	 * now remains allocated and sits on the unlinked list until the fs is
  	 * repaired.
  	 */
  	if (unlikely(mp->m_finobt_nores)) {
  		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ifree,
  				XFS_IFREE_SPACE_RES(mp), 0, XFS_TRANS_RESERVE,
  				&tp);
  	} else {
  		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ifree, 0, 0, 0, &tp);
  	}
  	if (error) {
  		if (error == -ENOSPC) {
  			xfs_warn_ratelimited(mp,
  			"Failed to remove inode(s) from unlinked list. "
  			"Please free space, unmount and run xfs_repair.");
  		} else {
  			ASSERT(XFS_FORCED_SHUTDOWN(mp));
  		}
  		return error;
  	}
  
  	xfs_ilock(ip, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, 0);
  
  	error = xfs_ifree(tp, ip);
  	if (error) {
  		/*
  		 * If we fail to free the inode, shut down.  The cancel
  		 * might do that, we need to make sure.  Otherwise the
  		 * inode might be lost for a long time or forever.
  		 */
  		if (!XFS_FORCED_SHUTDOWN(mp)) {
  			xfs_notice(mp, "%s: xfs_ifree returned error %d",
  				__func__, error);
  			xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
  		}
  		xfs_trans_cancel(tp);
  		xfs_iunlock(ip, XFS_ILOCK_EXCL);
  		return error;
  	}
  
  	/*
  	 * Credit the quota account(s). The inode is gone.
  	 */
  	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_ICOUNT, -1);
  
  	/*
  	 * Just ignore errors at this point.  There is nothing we can do except
  	 * to try to keep going. Make sure it's not a silent error.
  	 */
  	error = xfs_trans_commit(tp);
  	if (error)
  		xfs_notice(mp, "%s: xfs_trans_commit returned error %d",
  			__func__, error);
  
  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
  	return 0;
  }
  
  /*
   * xfs_inactive
   *
   * This is called when the vnode reference count for the vnode
   * goes to zero.  If the file has been unlinked, then it must
   * now be truncated.  Also, we clear all of the read-ahead state
   * kept for the inode here since the file is now closed.
   */
  void
  xfs_inactive(
  	xfs_inode_t	*ip)
  {
  	struct xfs_mount	*mp;
  	int			error;
  	int			truncate = 0;
  
  	/*
  	 * If the inode is already free, then there can be nothing
  	 * to clean up here.
  	 */
  	if (VFS_I(ip)->i_mode == 0) {
  		ASSERT(ip->i_df.if_broot_bytes == 0);
  		return;
  	}
  
  	mp = ip->i_mount;
  	ASSERT(!xfs_iflags_test(ip, XFS_IRECOVERY));
  
  	/* If this is a read-only mount, don't do this (would generate I/O) */
  	if (mp->m_flags & XFS_MOUNT_RDONLY)
  		return;
  
  	/* Try to clean out the cow blocks if there are any. */
  	if (xfs_inode_has_cow_data(ip))
  		xfs_reflink_cancel_cow_range(ip, 0, NULLFILEOFF, true);
  
  	if (VFS_I(ip)->i_nlink != 0) {
  		/*
  		 * force is true because we are evicting an inode from the
  		 * cache. Post-eof blocks must be freed, lest we end up with
  		 * broken free space accounting.
  		 *
  		 * Note: don't bother with iolock here since lockdep complains
  		 * about acquiring it in reclaim context. We have the only
  		 * reference to the inode at this point anyways.
  		 */
  		if (xfs_can_free_eofblocks(ip, true))
  			xfs_free_eofblocks(ip);
  
  		return;
  	}
  
  	if (S_ISREG(VFS_I(ip)->i_mode) &&
  	    (ip->i_d.di_size != 0 || XFS_ISIZE(ip) != 0 ||
  	     ip->i_d.di_nextents > 0 || ip->i_delayed_blks > 0))
  		truncate = 1;
  
  	error = xfs_qm_dqattach(ip);
  	if (error)
  		return;
  
  	if (S_ISLNK(VFS_I(ip)->i_mode))
  		error = xfs_inactive_symlink(ip);
  	else if (truncate)
  		error = xfs_inactive_truncate(ip);
  	if (error)
  		return;
  
  	/*
  	 * If there are attributes associated with the file then blow them away
  	 * now.  The code calls a routine that recursively deconstructs the
  	 * attribute fork. If also blows away the in-core attribute fork.
  	 */
  	if (XFS_IFORK_Q(ip)) {
  		error = xfs_attr_inactive(ip);
  		if (error)
  			return;
  	}
  
  	ASSERT(!ip->i_afp);
  	ASSERT(ip->i_d.di_anextents == 0);
  	ASSERT(ip->i_d.di_forkoff == 0);
  
  	/*
  	 * Free the inode.
  	 */
  	error = xfs_inactive_ifree(ip);
  	if (error)
  		return;
  
  	/*
  	 * Release the dquots held by inode, if any.
  	 */
  	xfs_qm_dqdetach(ip);
  }
  
  /*
   * In-Core Unlinked List Lookups
   * =============================
   *
   * Every inode is supposed to be reachable from some other piece of metadata
   * with the exception of the root directory.  Inodes with a connection to a
   * file descriptor but not linked from anywhere in the on-disk directory tree
   * are collectively known as unlinked inodes, though the filesystem itself
   * maintains links to these inodes so that on-disk metadata are consistent.
   *
   * XFS implements a per-AG on-disk hash table of unlinked inodes.  The AGI
   * header contains a number of buckets that point to an inode, and each inode
   * record has a pointer to the next inode in the hash chain.  This
   * singly-linked list causes scaling problems in the iunlink remove function
   * because we must walk that list to find the inode that points to the inode
   * being removed from the unlinked hash bucket list.
   *
   * What if we modelled the unlinked list as a collection of records capturing
   * "X.next_unlinked = Y" relations?  If we indexed those records on Y, we'd
   * have a fast way to look up unlinked list predecessors, which avoids the
   * slow list walk.  That's exactly what we do here (in-core) with a per-AG
   * rhashtable.
   *
   * Because this is a backref cache, we ignore operational failures since the
   * iunlink code can fall back to the slow bucket walk.  The only errors that
   * should bubble out are for obviously incorrect situations.
   *
   * All users of the backref cache MUST hold the AGI buffer lock to serialize
   * access or have otherwise provided for concurrency control.
   */
  
  /* Capture a "X.next_unlinked = Y" relationship. */
  struct xfs_iunlink {
  	struct rhash_head	iu_rhash_head;
  	xfs_agino_t		iu_agino;		/* X */
  	xfs_agino_t		iu_next_unlinked;	/* Y */
  };
  
  /* Unlinked list predecessor lookup hashtable construction */
  static int
  xfs_iunlink_obj_cmpfn(
  	struct rhashtable_compare_arg	*arg,
  	const void			*obj)
  {
  	const xfs_agino_t		*key = arg->key;
  	const struct xfs_iunlink	*iu = obj;
  
  	if (iu->iu_next_unlinked != *key)
  		return 1;
  	return 0;
  }
  
  static const struct rhashtable_params xfs_iunlink_hash_params = {
  	.min_size		= XFS_AGI_UNLINKED_BUCKETS,
  	.key_len		= sizeof(xfs_agino_t),
  	.key_offset		= offsetof(struct xfs_iunlink,
  					   iu_next_unlinked),
  	.head_offset		= offsetof(struct xfs_iunlink, iu_rhash_head),
  	.automatic_shrinking	= true,
  	.obj_cmpfn		= xfs_iunlink_obj_cmpfn,
  };
  
  /*
   * Return X, where X.next_unlinked == @agino.  Returns NULLAGINO if no such
   * relation is found.
   */
  static xfs_agino_t
  xfs_iunlink_lookup_backref(
  	struct xfs_perag	*pag,
  	xfs_agino_t		agino)
  {
  	struct xfs_iunlink	*iu;
  
  	iu = rhashtable_lookup_fast(&pag->pagi_unlinked_hash, &agino,
  			xfs_iunlink_hash_params);
  	return iu ? iu->iu_agino : NULLAGINO;
  }
  
  /*
   * Take ownership of an iunlink cache entry and insert it into the hash table.
   * If successful, the entry will be owned by the cache; if not, it is freed.
   * Either way, the caller does not own @iu after this call.
   */
  static int
  xfs_iunlink_insert_backref(
  	struct xfs_perag	*pag,
  	struct xfs_iunlink	*iu)
  {
  	int			error;
  
  	error = rhashtable_insert_fast(&pag->pagi_unlinked_hash,
  			&iu->iu_rhash_head, xfs_iunlink_hash_params);
  	/*
  	 * Fail loudly if there already was an entry because that's a sign of
  	 * corruption of in-memory data.  Also fail loudly if we see an error
  	 * code we didn't anticipate from the rhashtable code.  Currently we
  	 * only anticipate ENOMEM.
  	 */
  	if (error) {
  		WARN(error != -ENOMEM, "iunlink cache insert error %d", error);
  		kmem_free(iu);
  	}
  	/*
  	 * Absorb any runtime errors that aren't a result of corruption because
  	 * this is a cache and we can always fall back to bucket list scanning.
  	 */
  	if (error != 0 && error != -EEXIST)
  		error = 0;
  	return error;
  }
  
  /* Remember that @prev_agino.next_unlinked = @this_agino. */
  static int
  xfs_iunlink_add_backref(
  	struct xfs_perag	*pag,
  	xfs_agino_t		prev_agino,
  	xfs_agino_t		this_agino)
  {
  	struct xfs_iunlink	*iu;
  
  	if (XFS_TEST_ERROR(false, pag->pag_mount, XFS_ERRTAG_IUNLINK_FALLBACK))
  		return 0;
  
  	iu = kmem_zalloc(sizeof(*iu), KM_NOFS);
  	iu->iu_agino = prev_agino;
  	iu->iu_next_unlinked = this_agino;
  
  	return xfs_iunlink_insert_backref(pag, iu);
  }
  
  /*
   * Replace X.next_unlinked = @agino with X.next_unlinked = @next_unlinked.
   * If @next_unlinked is NULLAGINO, we drop the backref and exit.  If there
   * wasn't any such entry then we don't bother.
   */
  static int
  xfs_iunlink_change_backref(
  	struct xfs_perag	*pag,
  	xfs_agino_t		agino,
  	xfs_agino_t		next_unlinked)
  {
  	struct xfs_iunlink	*iu;
  	int			error;
  
  	/* Look up the old entry; if there wasn't one then exit. */
  	iu = rhashtable_lookup_fast(&pag->pagi_unlinked_hash, &agino,
  			xfs_iunlink_hash_params);
  	if (!iu)
  		return 0;
  
  	/*
  	 * Remove the entry.  This shouldn't ever return an error, but if we
  	 * couldn't remove the old entry we don't want to add it again to the
  	 * hash table, and if the entry disappeared on us then someone's
  	 * violated the locking rules and we need to fail loudly.  Either way
  	 * we cannot remove the inode because internal state is or would have
  	 * been corrupt.
  	 */
  	error = rhashtable_remove_fast(&pag->pagi_unlinked_hash,
  			&iu->iu_rhash_head, xfs_iunlink_hash_params);
  	if (error)
  		return error;
  
  	/* If there is no new next entry just free our item and return. */
  	if (next_unlinked == NULLAGINO) {
  		kmem_free(iu);
  		return 0;
  	}
  
  	/* Update the entry and re-add it to the hash table. */
  	iu->iu_next_unlinked = next_unlinked;
  	return xfs_iunlink_insert_backref(pag, iu);
  }
  
  /* Set up the in-core predecessor structures. */
  int
  xfs_iunlink_init(
  	struct xfs_perag	*pag)
  {
  	return rhashtable_init(&pag->pagi_unlinked_hash,
  			&xfs_iunlink_hash_params);
  }
  
  /* Free the in-core predecessor structures. */
  static void
  xfs_iunlink_free_item(
  	void			*ptr,
  	void			*arg)
  {
  	struct xfs_iunlink	*iu = ptr;
  	bool			*freed_anything = arg;
  
  	*freed_anything = true;
  	kmem_free(iu);
  }
  
  void
  xfs_iunlink_destroy(
  	struct xfs_perag	*pag)
  {
  	bool			freed_anything = false;
  
  	rhashtable_free_and_destroy(&pag->pagi_unlinked_hash,
  			xfs_iunlink_free_item, &freed_anything);
  
  	ASSERT(freed_anything == false || XFS_FORCED_SHUTDOWN(pag->pag_mount));
  }
  
  /*
   * Point the AGI unlinked bucket at an inode and log the results.  The caller
   * is responsible for validating the old value.
   */
  STATIC int
  xfs_iunlink_update_bucket(
  	struct xfs_trans	*tp,
  	xfs_agnumber_t		agno,
  	struct xfs_buf		*agibp,
  	unsigned int		bucket_index,
  	xfs_agino_t		new_agino)
  {
  	struct xfs_agi		*agi = agibp->b_addr;
  	xfs_agino_t		old_value;
  	int			offset;
  
  	ASSERT(xfs_verify_agino_or_null(tp->t_mountp, agno, new_agino));
  
  	old_value = be32_to_cpu(agi->agi_unlinked[bucket_index]);
  	trace_xfs_iunlink_update_bucket(tp->t_mountp, agno, bucket_index,
  			old_value, new_agino);
  
  	/*
  	 * We should never find the head of the list already set to the value
  	 * passed in because either we're adding or removing ourselves from the
  	 * head of the list.
  	 */
  	if (old_value == new_agino) {
  		xfs_buf_mark_corrupt(agibp);
  		return -EFSCORRUPTED;
  	}
  
  	agi->agi_unlinked[bucket_index] = cpu_to_be32(new_agino);
  	offset = offsetof(struct xfs_agi, agi_unlinked) +
  			(sizeof(xfs_agino_t) * bucket_index);
  	xfs_trans_log_buf(tp, agibp, offset, offset + sizeof(xfs_agino_t) - 1);
  	return 0;
  }
  
  /* Set an on-disk inode's next_unlinked pointer. */
  STATIC void
  xfs_iunlink_update_dinode(
  	struct xfs_trans	*tp,
  	xfs_agnumber_t		agno,
  	xfs_agino_t		agino,
  	struct xfs_buf		*ibp,
  	struct xfs_dinode	*dip,
  	struct xfs_imap		*imap,
  	xfs_agino_t		next_agino)
  {
  	struct xfs_mount	*mp = tp->t_mountp;
  	int			offset;
  
  	ASSERT(xfs_verify_agino_or_null(mp, agno, next_agino));
  
  	trace_xfs_iunlink_update_dinode(mp, agno, agino,
  			be32_to_cpu(dip->di_next_unlinked), next_agino);
  
  	dip->di_next_unlinked = cpu_to_be32(next_agino);
  	offset = imap->im_boffset +
  			offsetof(struct xfs_dinode, di_next_unlinked);
  
  	/* need to recalc the inode CRC if appropriate */
  	xfs_dinode_calc_crc(mp, dip);
  	xfs_trans_inode_buf(tp, ibp);
  	xfs_trans_log_buf(tp, ibp, offset, offset + sizeof(xfs_agino_t) - 1);
  	xfs_inobp_check(mp, ibp);
  }
  
  /* Set an in-core inode's unlinked pointer and return the old value. */
  STATIC int
  xfs_iunlink_update_inode(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip,
  	xfs_agnumber_t		agno,
  	xfs_agino_t		next_agino,
  	xfs_agino_t		*old_next_agino)
  {
  	struct xfs_mount	*mp = tp->t_mountp;
  	struct xfs_dinode	*dip;
  	struct xfs_buf		*ibp;
  	xfs_agino_t		old_value;
  	int			error;
  
  	ASSERT(xfs_verify_agino_or_null(mp, agno, next_agino));
  
  	error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp, 0, 0);
  	if (error)
  		return error;
  
  	/* Make sure the old pointer isn't garbage. */
  	old_value = be32_to_cpu(dip->di_next_unlinked);
  	if (!xfs_verify_agino_or_null(mp, agno, old_value)) {
  		xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__, dip,
  				sizeof(*dip), __this_address);
  		error = -EFSCORRUPTED;
  		goto out;
  	}
  
  	/*
  	 * Since we're updating a linked list, we should never find that the
  	 * current pointer is the same as the new value, unless we're
  	 * terminating the list.
  	 */
  	*old_next_agino = old_value;
  	if (old_value == next_agino) {
  		if (next_agino != NULLAGINO) {
  			xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__,
  					dip, sizeof(*dip), __this_address);
  			error = -EFSCORRUPTED;
  		}
  		goto out;
  	}
  
  	/* Ok, update the new pointer. */
  	xfs_iunlink_update_dinode(tp, agno, XFS_INO_TO_AGINO(mp, ip->i_ino),
  			ibp, dip, &ip->i_imap, next_agino);
  	return 0;
  out:
  	xfs_trans_brelse(tp, ibp);
  	return error;
  }
  
  /*
   * This is called when the inode's link count has gone to 0 or we are creating
   * a tmpfile via O_TMPFILE.  The inode @ip must have nlink == 0.
   *
   * We place the on-disk inode on a list in the AGI.  It will be pulled from this
   * list when the inode is freed.
   */
  STATIC int
  xfs_iunlink(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip)
  {
  	struct xfs_mount	*mp = tp->t_mountp;
  	struct xfs_agi		*agi;
  	struct xfs_buf		*agibp;
  	xfs_agino_t		next_agino;
  	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
  	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
  	short			bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
  	int			error;
  
  	ASSERT(VFS_I(ip)->i_nlink == 0);
  	ASSERT(VFS_I(ip)->i_mode != 0);
  	trace_xfs_iunlink(ip);
  
  	/* Get the agi buffer first.  It ensures lock ordering on the list. */
  	error = xfs_read_agi(mp, tp, agno, &agibp);
  	if (error)
  		return error;
  	agi = agibp->b_addr;
  
  	/*
  	 * Get the index into the agi hash table for the list this inode will
  	 * go on.  Make sure the pointer isn't garbage and that this inode
  	 * isn't already on the list.
  	 */
  	next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
  	if (next_agino == agino ||
  	    !xfs_verify_agino_or_null(mp, agno, next_agino)) {
  		xfs_buf_mark_corrupt(agibp);
  		return -EFSCORRUPTED;
  	}
  
  	if (next_agino != NULLAGINO) {
  		struct xfs_perag	*pag;
  		xfs_agino_t		old_agino;
  
  		/*
  		 * There is already another inode in the bucket, so point this
  		 * inode to the current head of the list.
  		 */
  		error = xfs_iunlink_update_inode(tp, ip, agno, next_agino,
  				&old_agino);
  		if (error)
  			return error;
  		ASSERT(old_agino == NULLAGINO);
  
  		/*
  		 * agino has been unlinked, add a backref from the next inode
  		 * back to agino.
  		 */
  		pag = xfs_perag_get(mp, agno);
  		error = xfs_iunlink_add_backref(pag, agino, next_agino);
  		xfs_perag_put(pag);
  		if (error)
  			return error;
  	}
  
  	/* Point the head of the list to point to this inode. */
  	return xfs_iunlink_update_bucket(tp, agno, agibp, bucket_index, agino);
  }
  
  /* Return the imap, dinode pointer, and buffer for an inode. */
  STATIC int
  xfs_iunlink_map_ino(
  	struct xfs_trans	*tp,
  	xfs_agnumber_t		agno,
  	xfs_agino_t		agino,
  	struct xfs_imap		*imap,
  	struct xfs_dinode	**dipp,
  	struct xfs_buf		**bpp)
  {
  	struct xfs_mount	*mp = tp->t_mountp;
  	int			error;
  
  	imap->im_blkno = 0;
  	error = xfs_imap(mp, tp, XFS_AGINO_TO_INO(mp, agno, agino), imap, 0);
  	if (error) {
  		xfs_warn(mp, "%s: xfs_imap returned error %d.",
  				__func__, error);
  		return error;
  	}
  
  	error = xfs_imap_to_bp(mp, tp, imap, dipp, bpp, 0, 0);
  	if (error) {
  		xfs_warn(mp, "%s: xfs_imap_to_bp returned error %d.",
  				__func__, error);
  		return error;
  	}
  
  	return 0;
  }
  
  /*
   * Walk the unlinked chain from @head_agino until we find the inode that
   * points to @target_agino.  Return the inode number, map, dinode pointer,
   * and inode cluster buffer of that inode as @agino, @imap, @dipp, and @bpp.
   *
   * @tp, @pag, @head_agino, and @target_agino are input parameters.
   * @agino, @imap, @dipp, and @bpp are all output parameters.
   *
   * Do not call this function if @target_agino is the head of the list.
   */
  STATIC int
  xfs_iunlink_map_prev(
  	struct xfs_trans	*tp,
  	xfs_agnumber_t		agno,
  	xfs_agino_t		head_agino,
  	xfs_agino_t		target_agino,
  	xfs_agino_t		*agino,
  	struct xfs_imap		*imap,
  	struct xfs_dinode	**dipp,
  	struct xfs_buf		**bpp,
  	struct xfs_perag	*pag)
  {
  	struct xfs_mount	*mp = tp->t_mountp;
  	xfs_agino_t		next_agino;
  	int			error;
  
  	ASSERT(head_agino != target_agino);
  	*bpp = NULL;
  
  	/* See if our backref cache can find it faster. */
  	*agino = xfs_iunlink_lookup_backref(pag, target_agino);
  	if (*agino != NULLAGINO) {
  		error = xfs_iunlink_map_ino(tp, agno, *agino, imap, dipp, bpp);
  		if (error)
  			return error;
  
  		if (be32_to_cpu((*dipp)->di_next_unlinked) == target_agino)
  			return 0;
  
  		/*
  		 * If we get here the cache contents were corrupt, so drop the
  		 * buffer and fall back to walking the bucket list.
  		 */
  		xfs_trans_brelse(tp, *bpp);
  		*bpp = NULL;
  		WARN_ON_ONCE(1);
  	}
  
  	trace_xfs_iunlink_map_prev_fallback(mp, agno);
  
  	/* Otherwise, walk the entire bucket until we find it. */
  	next_agino = head_agino;
  	while (next_agino != target_agino) {
  		xfs_agino_t	unlinked_agino;
  
  		if (*bpp)
  			xfs_trans_brelse(tp, *bpp);
  
  		*agino = next_agino;
  		error = xfs_iunlink_map_ino(tp, agno, next_agino, imap, dipp,
  				bpp);
  		if (error)
  			return error;
  
  		unlinked_agino = be32_to_cpu((*dipp)->di_next_unlinked);
  		/*
  		 * Make sure this pointer is valid and isn't an obvious
  		 * infinite loop.
  		 */
  		if (!xfs_verify_agino(mp, agno, unlinked_agino) ||
  		    next_agino == unlinked_agino) {
  			XFS_CORRUPTION_ERROR(__func__,
  					XFS_ERRLEVEL_LOW, mp,
  					*dipp, sizeof(**dipp));
  			error = -EFSCORRUPTED;
  			return error;
  		}
  		next_agino = unlinked_agino;
  	}
  
  	return 0;
  }
  
  /*
   * Pull the on-disk inode from the AGI unlinked list.
   */
  STATIC int
  xfs_iunlink_remove(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip)
  {
  	struct xfs_mount	*mp = tp->t_mountp;
  	struct xfs_agi		*agi;
  	struct xfs_buf		*agibp;
  	struct xfs_buf		*last_ibp;
  	struct xfs_dinode	*last_dip = NULL;
  	struct xfs_perag	*pag = NULL;
  	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
  	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
  	xfs_agino_t		next_agino;
  	xfs_agino_t		head_agino;
  	short			bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
  	int			error;
  
  	trace_xfs_iunlink_remove(ip);
  
  	/* Get the agi buffer first.  It ensures lock ordering on the list. */
  	error = xfs_read_agi(mp, tp, agno, &agibp);
  	if (error)
  		return error;
  	agi = agibp->b_addr;
  
  	/*
  	 * Get the index into the agi hash table for the list this inode will
  	 * go on.  Make sure the head pointer isn't garbage.
  	 */
  	head_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
  	if (!xfs_verify_agino(mp, agno, head_agino)) {
  		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
  				agi, sizeof(*agi));
  		return -EFSCORRUPTED;
  	}
  
  	/*
  	 * Set our inode's next_unlinked pointer to NULL and then return
  	 * the old pointer value so that we can update whatever was previous
  	 * to us in the list to point to whatever was next in the list.
  	 */
  	error = xfs_iunlink_update_inode(tp, ip, agno, NULLAGINO, &next_agino);
  	if (error)
  		return error;
  
  	/*
  	 * If there was a backref pointing from the next inode back to this
  	 * one, remove it because we've removed this inode from the list.
  	 *
  	 * Later, if this inode was in the middle of the list we'll update
  	 * this inode's backref to point from the next inode.
  	 */
  	if (next_agino != NULLAGINO) {
  		pag = xfs_perag_get(mp, agno);
  		error = xfs_iunlink_change_backref(pag, next_agino,
  				NULLAGINO);
  		if (error)
  			goto out;
  	}
  
  	if (head_agino == agino) {
  		/* Point the head of the list to the next unlinked inode. */
  		error = xfs_iunlink_update_bucket(tp, agno, agibp, bucket_index,
  				next_agino);
  		if (error)
  			goto out;
  	} else {
  		struct xfs_imap	imap;
  		xfs_agino_t	prev_agino;
  
  		if (!pag)
  			pag = xfs_perag_get(mp, agno);
  
  		/* We need to search the list for the inode being freed. */
  		error = xfs_iunlink_map_prev(tp, agno, head_agino, agino,
  				&prev_agino, &imap, &last_dip, &last_ibp,
  				pag);
  		if (error)
  			goto out;
  
  		/* Point the previous inode on the list to the next inode. */
  		xfs_iunlink_update_dinode(tp, agno, prev_agino, last_ibp,
  				last_dip, &imap, next_agino);
  
  		/*
  		 * Now we deal with the backref for this inode.  If this inode
  		 * pointed at a real inode, change the backref that pointed to
  		 * us to point to our old next.  If this inode was the end of
  		 * the list, delete the backref that pointed to us.  Note that
  		 * change_backref takes care of deleting the backref if
  		 * next_agino is NULLAGINO.
  		 */
  		error = xfs_iunlink_change_backref(pag, agino, next_agino);
  		if (error)
  			goto out;
  	}
  
  out:
  	if (pag)
  		xfs_perag_put(pag);
  	return error;
  }
  
  /*
   * Look up the inode number specified and mark it stale if it is found. If it is
   * dirty, return the inode so it can be attached to the cluster buffer so it can
   * be processed appropriately when the cluster free transaction completes.
   */
  static struct xfs_inode *
  xfs_ifree_get_one_inode(
  	struct xfs_perag	*pag,
  	struct xfs_inode	*free_ip,
  	xfs_ino_t		inum)
  {
  	struct xfs_mount	*mp = pag->pag_mount;
  	struct xfs_inode	*ip;
  
  retry:
  	rcu_read_lock();
  	ip = radix_tree_lookup(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, inum));
  
  	/* Inode not in memory, nothing to do */
  	if (!ip)
  		goto out_rcu_unlock;
  
  	/*
  	 * because this is an RCU protected lookup, we could find a recently
  	 * freed or even reallocated inode during the lookup. We need to check
  	 * under the i_flags_lock for a valid inode here. Skip it if it is not
  	 * valid, the wrong inode or stale.
  	 */
  	spin_lock(&ip->i_flags_lock);
  	if (ip->i_ino != inum || __xfs_iflags_test(ip, XFS_ISTALE)) {
  		spin_unlock(&ip->i_flags_lock);
  		goto out_rcu_unlock;
  	}
  	spin_unlock(&ip->i_flags_lock);
  
  	/*
  	 * Don't try to lock/unlock the current inode, but we _cannot_ skip the
  	 * other inodes that we did not find in the list attached to the buffer
  	 * and are not already marked stale. If we can't lock it, back off and
  	 * retry.
  	 */
  	if (ip != free_ip) {
  		if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
  			rcu_read_unlock();
  			delay(1);
  			goto retry;
  		}
  
  		/*
  		 * Check the inode number again in case we're racing with
  		 * freeing in xfs_reclaim_inode().  See the comments in that
  		 * function for more information as to why the initial check is
  		 * not sufficient.
  		 */
  		if (ip->i_ino != inum) {
  			xfs_iunlock(ip, XFS_ILOCK_EXCL);
  			goto out_rcu_unlock;
  		}
  	}
  	rcu_read_unlock();
  
  	xfs_iflock(ip);
  	xfs_iflags_set(ip, XFS_ISTALE);
  
  	/*
  	 * We don't need to attach clean inodes or those only with unlogged
  	 * changes (which we throw away, anyway).
  	 */
  	if (!ip->i_itemp || xfs_inode_clean(ip)) {
  		ASSERT(ip != free_ip);
  		xfs_ifunlock(ip);
  		xfs_iunlock(ip, XFS_ILOCK_EXCL);
  		goto out_no_inode;
  	}
  	return ip;
  
  out_rcu_unlock:
  	rcu_read_unlock();
  out_no_inode:
  	return NULL;
  }
  
  /*
   * A big issue when freeing the inode cluster is that we _cannot_ skip any
   * inodes that are in memory - they all must be marked stale and attached to
   * the cluster buffer.
   */
  STATIC int
  xfs_ifree_cluster(
  	xfs_inode_t		*free_ip,
  	xfs_trans_t		*tp,
  	struct xfs_icluster	*xic)
  {
  	xfs_mount_t		*mp = free_ip->i_mount;
  	int			nbufs;
  	int			i, j;
  	int			ioffset;
  	xfs_daddr_t		blkno;
  	xfs_buf_t		*bp;
  	xfs_inode_t		*ip;
  	xfs_inode_log_item_t	*iip;
  	struct xfs_log_item	*lip;
  	struct xfs_perag	*pag;
  	struct xfs_ino_geometry	*igeo = M_IGEO(mp);
  	xfs_ino_t		inum;
  	int			error;
  
  	inum = xic->first_ino;
  	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, inum));
  	nbufs = igeo->ialloc_blks / igeo->blocks_per_cluster;
  
  	for (j = 0; j < nbufs; j++, inum += igeo->inodes_per_cluster) {
  		/*
  		 * The allocation bitmap tells us which inodes of the chunk were
  		 * physically allocated. Skip the cluster if an inode falls into
  		 * a sparse region.
  		 */
  		ioffset = inum - xic->first_ino;
  		if ((xic->alloc & XFS_INOBT_MASK(ioffset)) == 0) {
  			ASSERT(ioffset % igeo->inodes_per_cluster == 0);
  			continue;
  		}
  
  		blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
  					 XFS_INO_TO_AGBNO(mp, inum));
  
  		/*
  		 * We obtain and lock the backing buffer first in the process
  		 * here, as we have to ensure that any dirty inode that we
  		 * can't get the flush lock on is attached to the buffer.
  		 * If we scan the in-memory inodes first, then buffer IO can
  		 * complete before we get a lock on it, and hence we may fail
  		 * to mark all the active inodes on the buffer stale.
  		 */
  		error = xfs_trans_get_buf(tp, mp->m_ddev_targp, blkno,
  				mp->m_bsize * igeo->blocks_per_cluster,
  				XBF_UNMAPPED, &bp);
  		if (error)
  			return error;
  
  		/*
  		 * This buffer may not have been correctly initialised as we
  		 * didn't read it from disk. That's not important because we are
  		 * only using to mark the buffer as stale in the log, and to
  		 * attach stale cached inodes on it. That means it will never be
  		 * dispatched for IO. If it is, we want to know about it, and we
  		 * want it to fail. We can acheive this by adding a write
  		 * verifier to the buffer.
  		 */
  		bp->b_ops = &xfs_inode_buf_ops;
  
  		/*
  		 * Walk the inodes already attached to the buffer and mark them
  		 * stale. These will all have the flush locks held, so an
  		 * in-memory inode walk can't lock them. By marking them all
  		 * stale first, we will not attempt to lock them in the loop
  		 * below as the XFS_ISTALE flag will be set.
  		 */
  		list_for_each_entry(lip, &bp->b_li_list, li_bio_list) {
  			if (lip->li_type == XFS_LI_INODE) {
  				iip = (xfs_inode_log_item_t *)lip;
  				ASSERT(iip->ili_logged == 1);
  				lip->li_cb = xfs_istale_done;
  				xfs_trans_ail_copy_lsn(mp->m_ail,
  							&iip->ili_flush_lsn,
  							&iip->ili_item.li_lsn);
  				xfs_iflags_set(iip->ili_inode, XFS_ISTALE);
  			}
  		}
  
  
  		/*
  		 * For each inode in memory attempt to add it to the inode
  		 * buffer and set it up for being staled on buffer IO
  		 * completion.  This is safe as we've locked out tail pushing
  		 * and flushing by locking the buffer.
  		 *
  		 * We have already marked every inode that was part of a
  		 * transaction stale above, which means there is no point in
  		 * even trying to lock them.
  		 */
  		for (i = 0; i < igeo->inodes_per_cluster; i++) {
  			ip = xfs_ifree_get_one_inode(pag, free_ip, inum + i);
  			if (!ip)
  				continue;
  
  			iip = ip->i_itemp;
  			iip->ili_last_fields = iip->ili_fields;
  			iip->ili_fields = 0;
  			iip->ili_fsync_fields = 0;
  			iip->ili_logged = 1;
  			xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
  						&iip->ili_item.li_lsn);
  
  			xfs_buf_attach_iodone(bp, xfs_istale_done,
  						  &iip->ili_item);
  
  			if (ip != free_ip)
  				xfs_iunlock(ip, XFS_ILOCK_EXCL);
  		}
  
  		xfs_trans_stale_inode_buf(tp, bp);
  		xfs_trans_binval(tp, bp);
  	}
  
  	xfs_perag_put(pag);
  	return 0;
  }
  
  /*
   * Free any local-format buffers sitting around before we reset to
   * extents format.
   */
  static inline void
  xfs_ifree_local_data(
  	struct xfs_inode	*ip,
  	int			whichfork)
  {
  	struct xfs_ifork	*ifp;
  
  	if (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_LOCAL)
  		return;
  
  	ifp = XFS_IFORK_PTR(ip, whichfork);
  	xfs_idata_realloc(ip, -ifp->if_bytes, whichfork);
  }
  
  /*
   * This is called to return an inode to the inode free list.
   * The inode should already be truncated to 0 length and have
   * no pages associated with it.  This routine also assumes that
   * the inode is already a part of the transaction.
   *
   * The on-disk copy of the inode will have been added to the list
   * of unlinked inodes in the AGI. We need to remove the inode from
   * that list atomically with respect to freeing it here.
   */
  int
  xfs_ifree(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*ip)
  {
  	int			error;
  	struct xfs_icluster	xic = { 0 };
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(VFS_I(ip)->i_nlink == 0);
  	ASSERT(ip->i_d.di_nextents == 0);
  	ASSERT(ip->i_d.di_anextents == 0);
  	ASSERT(ip->i_d.di_size == 0 || !S_ISREG(VFS_I(ip)->i_mode));
  	ASSERT(ip->i_d.di_nblocks == 0);
  
  	/*
  	 * Pull the on-disk inode from the AGI unlinked list.
  	 */
  	error = xfs_iunlink_remove(tp, ip);
  	if (error)
  		return error;
  
  	error = xfs_difree(tp, ip->i_ino, &xic);
  	if (error)
  		return error;
  
  	xfs_ifree_local_data(ip, XFS_DATA_FORK);
  	xfs_ifree_local_data(ip, XFS_ATTR_FORK);
  
  	VFS_I(ip)->i_mode = 0;		/* mark incore inode as free */
  	ip->i_d.di_flags = 0;
  	ip->i_d.di_flags2 = 0;
  	ip->i_d.di_dmevmask = 0;
  	ip->i_d.di_forkoff = 0;		/* mark the attr fork not in use */
  	ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
  	ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
  
  	/* Don't attempt to replay owner changes for a deleted inode */
  	ip->i_itemp->ili_fields &= ~(XFS_ILOG_AOWNER|XFS_ILOG_DOWNER);
  
  	/*
  	 * Bump the generation count so no one will be confused
  	 * by reincarnations of this inode.
  	 */
  	VFS_I(ip)->i_generation++;
  	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
  
  	if (xic.deleted)
  		error = xfs_ifree_cluster(ip, tp, &xic);
  
  	return error;
  }
  
  /*
   * This is called to unpin an inode.  The caller must have the inode locked
   * in at least shared mode so that the buffer cannot be subsequently pinned
   * once someone is waiting for it to be unpinned.
   */
  static void
  xfs_iunpin(
  	struct xfs_inode	*ip)
  {
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
  
  	trace_xfs_inode_unpin_nowait(ip, _RET_IP_);
  
  	/* Give the log a push to start the unpinning I/O */
  	xfs_log_force_lsn(ip->i_mount, ip->i_itemp->ili_last_lsn, 0, NULL);
  
  }
  
  static void
  __xfs_iunpin_wait(
  	struct xfs_inode	*ip)
  {
  	wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_IPINNED_BIT);
  	DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_IPINNED_BIT);
  
  	xfs_iunpin(ip);
  
  	do {
  		prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
  		if (xfs_ipincount(ip))
  			io_schedule();
  	} while (xfs_ipincount(ip));
  	finish_wait(wq, &wait.wq_entry);
  }
  
  void
  xfs_iunpin_wait(
  	struct xfs_inode	*ip)
  {
  	if (xfs_ipincount(ip))
  		__xfs_iunpin_wait(ip);
  }
  
  /*
   * Removing an inode from the namespace involves removing the directory entry
   * and dropping the link count on the inode. Removing the directory entry can
   * result in locking an AGF (directory blocks were freed) and removing a link
   * count can result in placing the inode on an unlinked list which results in
   * locking an AGI.
   *
   * The big problem here is that we have an ordering constraint on AGF and AGI
   * locking - inode allocation locks the AGI, then can allocate a new extent for
   * new inodes, locking the AGF after the AGI. Similarly, freeing the inode
   * removes the inode from the unlinked list, requiring that we lock the AGI
   * first, and then freeing the inode can result in an inode chunk being freed
   * and hence freeing disk space requiring that we lock an AGF.
   *
   * Hence the ordering that is imposed by other parts of the code is AGI before
   * AGF. This means we cannot remove the directory entry before we drop the inode
   * reference count and put it on the unlinked list as this results in a lock
   * order of AGF then AGI, and this can deadlock against inode allocation and
   * freeing. Therefore we must drop the link counts before we remove the
   * directory entry.
   *
   * This is still safe from a transactional point of view - it is not until we
   * get to xfs_defer_finish() that we have the possibility of multiple
   * transactions in this operation. Hence as long as we remove the directory
   * entry and drop the link count in the first transaction of the remove
   * operation, there are no transactional constraints on the ordering here.
   */
  int
  xfs_remove(
  	xfs_inode_t             *dp,
  	struct xfs_name		*name,
  	xfs_inode_t		*ip)
  {
  	xfs_mount_t		*mp = dp->i_mount;
  	xfs_trans_t             *tp = NULL;
  	int			is_dir = S_ISDIR(VFS_I(ip)->i_mode);
  	int                     error = 0;
  	uint			resblks;
  
  	trace_xfs_remove(dp, name);
  
  	if (XFS_FORCED_SHUTDOWN(mp))
  		return -EIO;
  
  	error = xfs_qm_dqattach(dp);
  	if (error)
  		goto std_return;
  
  	error = xfs_qm_dqattach(ip);
  	if (error)
  		goto std_return;
  
  	/*
  	 * We try to get the real space reservation first,
  	 * allowing for directory btree deletion(s) implying
  	 * possible bmap insert(s).  If we can't get the space
  	 * reservation then we use 0 instead, and avoid the bmap
  	 * btree insert(s) in the directory code by, if the bmap
  	 * insert tries to happen, instead trimming the LAST
  	 * block from the directory.
  	 */
  	resblks = XFS_REMOVE_SPACE_RES(mp);
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_remove, resblks, 0, 0, &tp);
  	if (error == -ENOSPC) {
  		resblks = 0;
  		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_remove, 0, 0, 0,
  				&tp);
  	}
  	if (error) {
  		ASSERT(error != -ENOSPC);
  		goto std_return;
  	}
  
  	xfs_lock_two_inodes(dp, XFS_ILOCK_EXCL, ip, XFS_ILOCK_EXCL);
  
  	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
  
  	/*
  	 * If we're removing a directory perform some additional validation.
  	 */
  	if (is_dir) {
  		ASSERT(VFS_I(ip)->i_nlink >= 2);
  		if (VFS_I(ip)->i_nlink != 2) {
  			error = -ENOTEMPTY;
  			goto out_trans_cancel;
  		}
  		if (!xfs_dir_isempty(ip)) {
  			error = -ENOTEMPTY;
  			goto out_trans_cancel;
  		}
  
  		/* Drop the link from ip's "..".  */
  		error = xfs_droplink(tp, dp);
  		if (error)
  			goto out_trans_cancel;
  
  		/* Drop the "." link from ip to self.  */
  		error = xfs_droplink(tp, ip);
  		if (error)
  			goto out_trans_cancel;
  	} else {
  		/*
  		 * When removing a non-directory we need to log the parent
  		 * inode here.  For a directory this is done implicitly
  		 * by the xfs_droplink call for the ".." entry.
  		 */
  		xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
  	}
  	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  
  	/* Drop the link from dp to ip. */
  	error = xfs_droplink(tp, ip);
  	if (error)
  		goto out_trans_cancel;
  
  	error = xfs_dir_removename(tp, dp, name, ip->i_ino, resblks);
  	if (error) {
  		ASSERT(error != -ENOENT);
  		goto out_trans_cancel;
  	}
  
  	/*
  	 * If this is a synchronous mount, make sure that the
  	 * remove transaction goes to disk before returning to
  	 * the user.
  	 */
  	if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
  		xfs_trans_set_sync(tp);
  
  	error = xfs_trans_commit(tp);
  	if (error)
  		goto std_return;
  
  	if (is_dir && xfs_inode_is_filestream(ip))
  		xfs_filestream_deassociate(ip);
  
  	return 0;
  
   out_trans_cancel:
  	xfs_trans_cancel(tp);
   std_return:
  	return error;
  }
  
  /*
   * Enter all inodes for a rename transaction into a sorted array.
   */
  #define __XFS_SORT_INODES	5
  STATIC void
  xfs_sort_for_rename(
  	struct xfs_inode	*dp1,	/* in: old (source) directory inode */
  	struct xfs_inode	*dp2,	/* in: new (target) directory inode */
  	struct xfs_inode	*ip1,	/* in: inode of old entry */
  	struct xfs_inode	*ip2,	/* in: inode of new entry */
  	struct xfs_inode	*wip,	/* in: whiteout inode */
  	struct xfs_inode	**i_tab,/* out: sorted array of inodes */
  	int			*num_inodes)  /* in/out: inodes in array */
  {
  	int			i, j;
  
  	ASSERT(*num_inodes == __XFS_SORT_INODES);
  	memset(i_tab, 0, *num_inodes * sizeof(struct xfs_inode *));
  
  	/*
  	 * i_tab contains a list of pointers to inodes.  We initialize
  	 * the table here & we'll sort it.  We will then use it to
  	 * order the acquisition of the inode locks.
  	 *
  	 * Note that the table may contain duplicates.  e.g., dp1 == dp2.
  	 */
  	i = 0;
  	i_tab[i++] = dp1;
  	i_tab[i++] = dp2;
  	i_tab[i++] = ip1;
  	if (ip2)
  		i_tab[i++] = ip2;
  	if (wip)
  		i_tab[i++] = wip;
  	*num_inodes = i;
  
  	/*
  	 * Sort the elements via bubble sort.  (Remember, there are at
  	 * most 5 elements to sort, so this is adequate.)
  	 */
  	for (i = 0; i < *num_inodes; i++) {
  		for (j = 1; j < *num_inodes; j++) {
  			if (i_tab[j]->i_ino < i_tab[j-1]->i_ino) {
  				struct xfs_inode *temp = i_tab[j];
  				i_tab[j] = i_tab[j-1];
  				i_tab[j-1] = temp;
  			}
  		}
  	}
  }
  
  static int
  xfs_finish_rename(
  	struct xfs_trans	*tp)
  {
  	/*
  	 * If this is a synchronous mount, make sure that the rename transaction
  	 * goes to disk before returning to the user.
  	 */
  	if (tp->t_mountp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC))
  		xfs_trans_set_sync(tp);
  
  	return xfs_trans_commit(tp);
  }
  
  /*
   * xfs_cross_rename()
   *
   * responsible for handling RENAME_EXCHANGE flag in renameat2() sytemcall
   */
  STATIC int
  xfs_cross_rename(
  	struct xfs_trans	*tp,
  	struct xfs_inode	*dp1,
  	struct xfs_name		*name1,
  	struct xfs_inode	*ip1,
  	struct xfs_inode	*dp2,
  	struct xfs_name		*name2,
  	struct xfs_inode	*ip2,
  	int			spaceres)
  {
  	int		error = 0;
  	int		ip1_flags = 0;
  	int		ip2_flags = 0;
  	int		dp2_flags = 0;
  
  	/* Swap inode number for dirent in first parent */
  	error = xfs_dir_replace(tp, dp1, name1, ip2->i_ino, spaceres);
  	if (error)
  		goto out_trans_abort;
  
  	/* Swap inode number for dirent in second parent */
  	error = xfs_dir_replace(tp, dp2, name2, ip1->i_ino, spaceres);
  	if (error)
  		goto out_trans_abort;
  
  	/*
  	 * If we're renaming one or more directories across different parents,
  	 * update the respective ".." entries (and link counts) to match the new
  	 * parents.
  	 */
  	if (dp1 != dp2) {
  		dp2_flags = XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
  
  		if (S_ISDIR(VFS_I(ip2)->i_mode)) {
  			error = xfs_dir_replace(tp, ip2, &xfs_name_dotdot,
  						dp1->i_ino, spaceres);
  			if (error)
  				goto out_trans_abort;
  
  			/* transfer ip2 ".." reference to dp1 */
  			if (!S_ISDIR(VFS_I(ip1)->i_mode)) {
  				error = xfs_droplink(tp, dp2);
  				if (error)
  					goto out_trans_abort;
  				xfs_bumplink(tp, dp1);
  			}
  
  			/*
  			 * Although ip1 isn't changed here, userspace needs
  			 * to be warned about the change, so that applications
  			 * relying on it (like backup ones), will properly
  			 * notify the change
  			 */
  			ip1_flags |= XFS_ICHGTIME_CHG;
  			ip2_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
  		}
  
  		if (S_ISDIR(VFS_I(ip1)->i_mode)) {
  			error = xfs_dir_replace(tp, ip1, &xfs_name_dotdot,
  						dp2->i_ino, spaceres);
  			if (error)
  				goto out_trans_abort;
  
  			/* transfer ip1 ".." reference to dp2 */
  			if (!S_ISDIR(VFS_I(ip2)->i_mode)) {
  				error = xfs_droplink(tp, dp1);
  				if (error)
  					goto out_trans_abort;
  				xfs_bumplink(tp, dp2);
  			}
  
  			/*
  			 * Although ip2 isn't changed here, userspace needs
  			 * to be warned about the change, so that applications
  			 * relying on it (like backup ones), will properly
  			 * notify the change
  			 */
  			ip1_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
  			ip2_flags |= XFS_ICHGTIME_CHG;
  		}
  	}
  
  	if (ip1_flags) {
  		xfs_trans_ichgtime(tp, ip1, ip1_flags);
  		xfs_trans_log_inode(tp, ip1, XFS_ILOG_CORE);
  	}
  	if (ip2_flags) {
  		xfs_trans_ichgtime(tp, ip2, ip2_flags);
  		xfs_trans_log_inode(tp, ip2, XFS_ILOG_CORE);
  	}
  	if (dp2_flags) {
  		xfs_trans_ichgtime(tp, dp2, dp2_flags);
  		xfs_trans_log_inode(tp, dp2, XFS_ILOG_CORE);
  	}
  	xfs_trans_ichgtime(tp, dp1, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, dp1, XFS_ILOG_CORE);
  	return xfs_finish_rename(tp);
  
  out_trans_abort:
  	xfs_trans_cancel(tp);
  	return error;
  }
  
  /*
   * xfs_rename_alloc_whiteout()
   *
   * Return a referenced, unlinked, unlocked inode that that can be used as a
   * whiteout in a rename transaction. We use a tmpfile inode here so that if we
   * crash between allocating the inode and linking it into the rename transaction
   * recovery will free the inode and we won't leak it.
   */
  static int
  xfs_rename_alloc_whiteout(
  	struct xfs_inode	*dp,
  	struct xfs_inode	**wip)
  {
  	struct xfs_inode	*tmpfile;
  	int			error;
  
  	error = xfs_create_tmpfile(dp, S_IFCHR | WHITEOUT_MODE, &tmpfile);
  	if (error)
  		return error;
  
  	/*
  	 * Prepare the tmpfile inode as if it were created through the VFS.
  	 * Complete the inode setup and flag it as linkable.  nlink is already
  	 * zero, so we can skip the drop_nlink.
  	 */
  	xfs_setup_iops(tmpfile);
  	xfs_finish_inode_setup(tmpfile);
  	VFS_I(tmpfile)->i_state |= I_LINKABLE;
  
  	*wip = tmpfile;
  	return 0;
  }
  
  /*
   * xfs_rename
   */
  int
  xfs_rename(
  	struct xfs_inode	*src_dp,
  	struct xfs_name		*src_name,
  	struct xfs_inode	*src_ip,
  	struct xfs_inode	*target_dp,
  	struct xfs_name		*target_name,
  	struct xfs_inode	*target_ip,
  	unsigned int		flags)
  {
  	struct xfs_mount	*mp = src_dp->i_mount;
  	struct xfs_trans	*tp;
  	struct xfs_inode	*wip = NULL;		/* whiteout inode */
  	struct xfs_inode	*inodes[__XFS_SORT_INODES];
  	struct xfs_buf		*agibp;
  	int			num_inodes = __XFS_SORT_INODES;
  	bool			new_parent = (src_dp != target_dp);
  	bool			src_is_directory = S_ISDIR(VFS_I(src_ip)->i_mode);
  	int			spaceres;
  	int			error;
  
  	trace_xfs_rename(src_dp, target_dp, src_name, target_name);
  
  	if ((flags & RENAME_EXCHANGE) && !target_ip)
  		return -EINVAL;
  
  	/*
  	 * If we are doing a whiteout operation, allocate the whiteout inode
  	 * we will be placing at the target and ensure the type is set
  	 * appropriately.
  	 */
  	if (flags & RENAME_WHITEOUT) {
  		ASSERT(!(flags & (RENAME_NOREPLACE | RENAME_EXCHANGE)));
  		error = xfs_rename_alloc_whiteout(target_dp, &wip);
  		if (error)
  			return error;
  
  		/* setup target dirent info as whiteout */
  		src_name->type = XFS_DIR3_FT_CHRDEV;
  	}
  
  	xfs_sort_for_rename(src_dp, target_dp, src_ip, target_ip, wip,
  				inodes, &num_inodes);
  
  	spaceres = XFS_RENAME_SPACE_RES(mp, target_name->len);
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_rename, spaceres, 0, 0, &tp);
  	if (error == -ENOSPC) {
  		spaceres = 0;
  		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_rename, 0, 0, 0,
  				&tp);
  	}
  	if (error)
  		goto out_release_wip;
  
  	/*
  	 * Attach the dquots to the inodes
  	 */
  	error = xfs_qm_vop_rename_dqattach(inodes);
  	if (error)
  		goto out_trans_cancel;
  
  	/*
  	 * Lock all the participating inodes. Depending upon whether
  	 * the target_name exists in the target directory, and
  	 * whether the target directory is the same as the source
  	 * directory, we can lock from 2 to 4 inodes.
  	 */
  	xfs_lock_inodes(inodes, num_inodes, XFS_ILOCK_EXCL);
  
  	/*
  	 * Join all the inodes to the transaction. From this point on,
  	 * we can rely on either trans_commit or trans_cancel to unlock
  	 * them.
  	 */
  	xfs_trans_ijoin(tp, src_dp, XFS_ILOCK_EXCL);
  	if (new_parent)
  		xfs_trans_ijoin(tp, target_dp, XFS_ILOCK_EXCL);
  	xfs_trans_ijoin(tp, src_ip, XFS_ILOCK_EXCL);
  	if (target_ip)
  		xfs_trans_ijoin(tp, target_ip, XFS_ILOCK_EXCL);
  	if (wip)
  		xfs_trans_ijoin(tp, wip, XFS_ILOCK_EXCL);
  
  	/*
  	 * If we are using project inheritance, we only allow renames
  	 * into our tree when the project IDs are the same; else the
  	 * tree quota mechanism would be circumvented.
  	 */
  	if (unlikely((target_dp->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) &&
  		     target_dp->i_d.di_projid != src_ip->i_d.di_projid)) {
  		error = -EXDEV;
  		goto out_trans_cancel;
  	}
  
  	/* RENAME_EXCHANGE is unique from here on. */
  	if (flags & RENAME_EXCHANGE)
  		return xfs_cross_rename(tp, src_dp, src_name, src_ip,
  					target_dp, target_name, target_ip,
  					spaceres);
  
  	/*
  	 * Check for expected errors before we dirty the transaction
  	 * so we can return an error without a transaction abort.
  	 */
  	if (target_ip == NULL) {
  		/*
  		 * If there's no space reservation, check the entry will
  		 * fit before actually inserting it.
  		 */
  		if (!spaceres) {
  			error = xfs_dir_canenter(tp, target_dp, target_name);
  			if (error)
  				goto out_trans_cancel;
  		}
  	} else {
  		/*
  		 * If target exists and it's a directory, check that whether
  		 * it can be destroyed.
  		 */
  		if (S_ISDIR(VFS_I(target_ip)->i_mode) &&
  		    (!xfs_dir_isempty(target_ip) ||
  		     (VFS_I(target_ip)->i_nlink > 2))) {
  			error = -EEXIST;
  			goto out_trans_cancel;
  		}
  	}
  
  	/*
  	 * Directory entry creation below may acquire the AGF. Remove
  	 * the whiteout from the unlinked list first to preserve correct
  	 * AGI/AGF locking order. This dirties the transaction so failures
  	 * after this point will abort and log recovery will clean up the
  	 * mess.
  	 *
  	 * For whiteouts, we need to bump the link count on the whiteout
  	 * inode. After this point, we have a real link, clear the tmpfile
  	 * state flag from the inode so it doesn't accidentally get misused
  	 * in future.
  	 */
  	if (wip) {
  		ASSERT(VFS_I(wip)->i_nlink == 0);
  		error = xfs_iunlink_remove(tp, wip);
  		if (error)
  			goto out_trans_cancel;
  
  		xfs_bumplink(tp, wip);
  		VFS_I(wip)->i_state &= ~I_LINKABLE;
  	}
  
  	/*
  	 * Set up the target.
  	 */
  	if (target_ip == NULL) {
  		/*
  		 * If target does not exist and the rename crosses
  		 * directories, adjust the target directory link count
  		 * to account for the ".." reference from the new entry.
  		 */
  		error = xfs_dir_createname(tp, target_dp, target_name,
  					   src_ip->i_ino, spaceres);
  		if (error)
  			goto out_trans_cancel;
  
  		xfs_trans_ichgtime(tp, target_dp,
  					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  
  		if (new_parent && src_is_directory) {
  			xfs_bumplink(tp, target_dp);
  		}
  	} else { /* target_ip != NULL */
  		/*
  		 * Link the source inode under the target name.
  		 * If the source inode is a directory and we are moving
  		 * it across directories, its ".." entry will be
  		 * inconsistent until we replace that down below.
  		 *
  		 * In case there is already an entry with the same
  		 * name at the destination directory, remove it first.
  		 */
  
  		/*
  		 * Check whether the replace operation will need to allocate
  		 * blocks.  This happens when the shortform directory lacks
  		 * space and we have to convert it to a block format directory.
  		 * When more blocks are necessary, we must lock the AGI first
  		 * to preserve locking order (AGI -> AGF).
  		 */
  		if (xfs_dir2_sf_replace_needblock(target_dp, src_ip->i_ino)) {
  			error = xfs_read_agi(mp, tp,
  					XFS_INO_TO_AGNO(mp, target_ip->i_ino),
  					&agibp);
  			if (error)
  				goto out_trans_cancel;
  		}
  
  		error = xfs_dir_replace(tp, target_dp, target_name,
  					src_ip->i_ino, spaceres);
  		if (error)
  			goto out_trans_cancel;
  
  		xfs_trans_ichgtime(tp, target_dp,
  					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  
  		/*
  		 * Decrement the link count on the target since the target
  		 * dir no longer points to it.
  		 */
  		error = xfs_droplink(tp, target_ip);
  		if (error)
  			goto out_trans_cancel;
  
  		if (src_is_directory) {
  			/*
  			 * Drop the link from the old "." entry.
  			 */
  			error = xfs_droplink(tp, target_ip);
  			if (error)
  				goto out_trans_cancel;
  		}
  	} /* target_ip != NULL */
  
  	/*
  	 * Remove the source.
  	 */
  	if (new_parent && src_is_directory) {
  		/*
  		 * Rewrite the ".." entry to point to the new
  		 * directory.
  		 */
  		error = xfs_dir_replace(tp, src_ip, &xfs_name_dotdot,
  					target_dp->i_ino, spaceres);
  		ASSERT(error != -EEXIST);
  		if (error)
  			goto out_trans_cancel;
  	}
  
  	/*
  	 * We always want to hit the ctime on the source inode.
  	 *
  	 * This isn't strictly required by the standards since the source
  	 * inode isn't really being changed, but old unix file systems did
  	 * it and some incremental backup programs won't work without it.
  	 */
  	xfs_trans_ichgtime(tp, src_ip, XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, src_ip, XFS_ILOG_CORE);
  
  	/*
  	 * Adjust the link count on src_dp.  This is necessary when
  	 * renaming a directory, either within one parent when
  	 * the target existed, or across two parent directories.
  	 */
  	if (src_is_directory && (new_parent || target_ip != NULL)) {
  
  		/*
  		 * Decrement link count on src_directory since the
  		 * entry that's moved no longer points to it.
  		 */
  		error = xfs_droplink(tp, src_dp);
  		if (error)
  			goto out_trans_cancel;
  	}
  
  	/*
  	 * For whiteouts, we only need to update the source dirent with the
  	 * inode number of the whiteout inode rather than removing it
  	 * altogether.
  	 */
  	if (wip) {
  		error = xfs_dir_replace(tp, src_dp, src_name, wip->i_ino,
  					spaceres);
  	} else
  		error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
  					   spaceres);
  	if (error)
  		goto out_trans_cancel;
  
  	xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
  	xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);
  	if (new_parent)
  		xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
  
  	error = xfs_finish_rename(tp);
  	if (wip)
  		xfs_irele(wip);
  	return error;
  
  out_trans_cancel:
  	xfs_trans_cancel(tp);
  out_release_wip:
  	if (wip)
  		xfs_irele(wip);
  	return error;
  }
  
  STATIC int
  xfs_iflush_cluster(
  	struct xfs_inode	*ip,
  	struct xfs_buf		*bp)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_perag	*pag;
  	unsigned long		first_index, mask;
  	int			cilist_size;
  	struct xfs_inode	**cilist;
  	struct xfs_inode	*cip;
  	struct xfs_ino_geometry	*igeo = M_IGEO(mp);
  	int			nr_found;
  	int			clcount = 0;
  	int			i;
  
  	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
  
  	cilist_size = igeo->inodes_per_cluster * sizeof(struct xfs_inode *);
  	cilist = kmem_alloc(cilist_size, KM_MAYFAIL|KM_NOFS);
  	if (!cilist)
  		goto out_put;
  
  	mask = ~(igeo->inodes_per_cluster - 1);
  	first_index = XFS_INO_TO_AGINO(mp, ip->i_ino) & mask;
  	rcu_read_lock();
  	/* really need a gang lookup range call here */
  	nr_found = radix_tree_gang_lookup(&pag->pag_ici_root, (void**)cilist,
  					first_index, igeo->inodes_per_cluster);
  	if (nr_found == 0)
  		goto out_free;
  
  	for (i = 0; i < nr_found; i++) {
  		cip = cilist[i];
  		if (cip == ip)
  			continue;
  
  		/*
  		 * because this is an RCU protected lookup, we could find a
  		 * recently freed or even reallocated inode during the lookup.
  		 * We need to check under the i_flags_lock for a valid inode
  		 * here. Skip it if it is not valid or the wrong inode.
  		 */
  		spin_lock(&cip->i_flags_lock);
  		if (!cip->i_ino ||
  		    __xfs_iflags_test(cip, XFS_ISTALE)) {
  			spin_unlock(&cip->i_flags_lock);
  			continue;
  		}
  
  		/*
  		 * Once we fall off the end of the cluster, no point checking
  		 * any more inodes in the list because they will also all be
  		 * outside the cluster.
  		 */
  		if ((XFS_INO_TO_AGINO(mp, cip->i_ino) & mask) != first_index) {
  			spin_unlock(&cip->i_flags_lock);
  			break;
  		}
  		spin_unlock(&cip->i_flags_lock);
  
  		/*
  		 * Do an un-protected check to see if the inode is dirty and
  		 * is a candidate for flushing.  These checks will be repeated
  		 * later after the appropriate locks are acquired.
  		 */
  		if (xfs_inode_clean(cip) && xfs_ipincount(cip) == 0)
  			continue;
  
  		/*
  		 * Try to get locks.  If any are unavailable or it is pinned,
  		 * then this inode cannot be flushed and is skipped.
  		 */
  
  		if (!xfs_ilock_nowait(cip, XFS_ILOCK_SHARED))
  			continue;
  		if (!xfs_iflock_nowait(cip)) {
  			xfs_iunlock(cip, XFS_ILOCK_SHARED);
  			continue;
  		}
  		if (xfs_ipincount(cip)) {
  			xfs_ifunlock(cip);
  			xfs_iunlock(cip, XFS_ILOCK_SHARED);
  			continue;
  		}
  
  
  		/*
  		 * Check the inode number again, just to be certain we are not
  		 * racing with freeing in xfs_reclaim_inode(). See the comments
  		 * in that function for more information as to why the initial
  		 * check is not sufficient.
  		 */
  		if (!cip->i_ino) {
  			xfs_ifunlock(cip);
  			xfs_iunlock(cip, XFS_ILOCK_SHARED);
  			continue;
  		}
  
  		/*
  		 * arriving here means that this inode can be flushed.  First
  		 * re-check that it's dirty before flushing.
  		 */
  		if (!xfs_inode_clean(cip)) {
  			int	error;
  			error = xfs_iflush_int(cip, bp);
  			if (error) {
  				xfs_iunlock(cip, XFS_ILOCK_SHARED);
  				goto cluster_corrupt_out;
  			}
  			clcount++;
  		} else {
  			xfs_ifunlock(cip);
  		}
  		xfs_iunlock(cip, XFS_ILOCK_SHARED);
  	}
  
  	if (clcount) {
  		XFS_STATS_INC(mp, xs_icluster_flushcnt);
  		XFS_STATS_ADD(mp, xs_icluster_flushinode, clcount);
  	}
  
  out_free:
  	rcu_read_unlock();
  	kmem_free(cilist);
  out_put:
  	xfs_perag_put(pag);
  	return 0;
  
  
  cluster_corrupt_out:
  	/*
  	 * Corruption detected in the clustering loop.  Invalidate the
  	 * inode buffer and shut down the filesystem.
  	 */
  	rcu_read_unlock();
  
  	/*
  	 * We'll always have an inode attached to the buffer for completion
  	 * process by the time we are called from xfs_iflush(). Hence we have
  	 * always need to do IO completion processing to abort the inodes
  	 * attached to the buffer.  handle them just like the shutdown case in
  	 * xfs_buf_submit().
  	 */
  	ASSERT(bp->b_iodone);
  	bp->b_flags |= XBF_ASYNC;
  	bp->b_flags &= ~XBF_DONE;
  	xfs_buf_stale(bp);
  	xfs_buf_ioerror(bp, -EIO);
  	xfs_buf_ioend(bp);
  
  	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
  
  	/* abort the corrupt inode, as it was not attached to the buffer */
  	xfs_iflush_abort(cip, false);
  	kmem_free(cilist);
  	xfs_perag_put(pag);
  	return -EFSCORRUPTED;
  }
  
  /*
   * Flush dirty inode metadata into the backing buffer.
   *
   * The caller must have the inode lock and the inode flush lock held.  The
   * inode lock will still be held upon return to the caller, and the inode
   * flush lock will be released after the inode has reached the disk.
   *
   * The caller must write out the buffer returned in *bpp and release it.
   */
  int
  xfs_iflush(
  	struct xfs_inode	*ip,
  	struct xfs_buf		**bpp)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_buf		*bp = NULL;
  	struct xfs_dinode	*dip;
  	int			error;
  
  	XFS_STATS_INC(mp, xs_iflush_count);
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
  	ASSERT(xfs_isiflocked(ip));
  	ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
  	       ip->i_d.di_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
  
  	*bpp = NULL;
  
  	xfs_iunpin_wait(ip);
  
  	/*
  	 * For stale inodes we cannot rely on the backing buffer remaining
  	 * stale in cache for the remaining life of the stale inode and so
  	 * xfs_imap_to_bp() below may give us a buffer that no longer contains
  	 * inodes below. We have to check this after ensuring the inode is
  	 * unpinned so that it is safe to reclaim the stale inode after the
  	 * flush call.
  	 */
  	if (xfs_iflags_test(ip, XFS_ISTALE)) {
  		xfs_ifunlock(ip);
  		return 0;
  	}
  
  	/*
  	 * This may have been unpinned because the filesystem is shutting
  	 * down forcibly. If that's the case we must not write this inode
  	 * to disk, because the log record didn't make it to disk.
  	 *
  	 * We also have to remove the log item from the AIL in this case,
  	 * as we wait for an empty AIL as part of the unmount process.
  	 */
  	if (XFS_FORCED_SHUTDOWN(mp)) {
  		error = -EIO;
  		goto abort_out;
  	}
  
  	/*
  	 * Get the buffer containing the on-disk inode. We are doing a try-lock
  	 * operation here, so we may get  an EAGAIN error. In that case, we
  	 * simply want to return with the inode still dirty.
  	 *
  	 * If we get any other error, we effectively have a corruption situation
  	 * and we cannot flush the inode, so we treat it the same as failing
  	 * xfs_iflush_int().
  	 */
  	error = xfs_imap_to_bp(mp, NULL, &ip->i_imap, &dip, &bp, XBF_TRYLOCK,
  			       0);
  	if (error == -EAGAIN) {
  		xfs_ifunlock(ip);
  		return error;
  	}
  	if (error)
  		goto corrupt_out;
  
  	/*
  	 * First flush out the inode that xfs_iflush was called with.
  	 */
  	error = xfs_iflush_int(ip, bp);
  	if (error)
  		goto corrupt_out;
  
  	/*
  	 * If the buffer is pinned then push on the log now so we won't
  	 * get stuck waiting in the write for too long.
  	 */
  	if (xfs_buf_ispinned(bp))
  		xfs_log_force(mp, 0);
  
  	/*
  	 * inode clustering: try to gather other inodes into this write
  	 *
  	 * Note: Any error during clustering will result in the filesystem
  	 * being shut down and completion callbacks run on the cluster buffer.
  	 * As we have already flushed and attached this inode to the buffer,
  	 * it has already been aborted and released by xfs_iflush_cluster() and
  	 * so we have no further error handling to do here.
  	 */
  	error = xfs_iflush_cluster(ip, bp);
  	if (error)
  		return error;
  
  	*bpp = bp;
  	return 0;
  
  corrupt_out:
  	if (bp)
  		xfs_buf_relse(bp);
  	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
  abort_out:
  	/* abort the corrupt inode, as it was not attached to the buffer */
  	xfs_iflush_abort(ip, false);
  	return error;
  }
  
  /*
   * If there are inline format data / attr forks attached to this inode,
   * make sure they're not corrupt.
   */
  bool
  xfs_inode_verify_forks(
  	struct xfs_inode	*ip)
  {
  	struct xfs_ifork	*ifp;
  	xfs_failaddr_t		fa;
  
  	fa = xfs_ifork_verify_data(ip, &xfs_default_ifork_ops);
  	if (fa) {
  		ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
  		xfs_inode_verifier_error(ip, -EFSCORRUPTED, "data fork",
  				ifp->if_u1.if_data, ifp->if_bytes, fa);
  		return false;
  	}
  
  	fa = xfs_ifork_verify_attr(ip, &xfs_default_ifork_ops);
  	if (fa) {
  		ifp = XFS_IFORK_PTR(ip, XFS_ATTR_FORK);
  		xfs_inode_verifier_error(ip, -EFSCORRUPTED, "attr fork",
  				ifp ? ifp->if_u1.if_data : NULL,
  				ifp ? ifp->if_bytes : 0, fa);
  		return false;
  	}
  	return true;
  }
  
  STATIC int
  xfs_iflush_int(
  	struct xfs_inode	*ip,
  	struct xfs_buf		*bp)
  {
  	struct xfs_inode_log_item *iip = ip->i_itemp;
  	struct xfs_dinode	*dip;
  	struct xfs_mount	*mp = ip->i_mount;
  
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
  	ASSERT(xfs_isiflocked(ip));
  	ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
  	       ip->i_d.di_nextents > XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK));
  	ASSERT(iip != NULL && iip->ili_fields != 0);
  
  	/* set *dip = inode's place in the buffer */
  	dip = xfs_buf_offset(bp, ip->i_imap.im_boffset);
  
  	if (XFS_TEST_ERROR(dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC),
  			       mp, XFS_ERRTAG_IFLUSH_1)) {
  		xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  			"%s: Bad inode %Lu magic number 0x%x, ptr "PTR_FMT,
  			__func__, ip->i_ino, be16_to_cpu(dip->di_magic), dip);
  		goto corrupt_out;
  	}
  	if (S_ISREG(VFS_I(ip)->i_mode)) {
  		if (XFS_TEST_ERROR(
  		    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
  		    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE),
  		    mp, XFS_ERRTAG_IFLUSH_3)) {
  			xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  				"%s: Bad regular inode %Lu, ptr "PTR_FMT,
  				__func__, ip->i_ino, ip);
  			goto corrupt_out;
  		}
  	} else if (S_ISDIR(VFS_I(ip)->i_mode)) {
  		if (XFS_TEST_ERROR(
  		    (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS) &&
  		    (ip->i_d.di_format != XFS_DINODE_FMT_BTREE) &&
  		    (ip->i_d.di_format != XFS_DINODE_FMT_LOCAL),
  		    mp, XFS_ERRTAG_IFLUSH_4)) {
  			xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  				"%s: Bad directory inode %Lu, ptr "PTR_FMT,
  				__func__, ip->i_ino, ip);
  			goto corrupt_out;
  		}
  	}
  	if (XFS_TEST_ERROR(ip->i_d.di_nextents + ip->i_d.di_anextents >
  				ip->i_d.di_nblocks, mp, XFS_ERRTAG_IFLUSH_5)) {
  		xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  			"%s: detected corrupt incore inode %Lu, "
  			"total extents = %d, nblocks = %Ld, ptr "PTR_FMT,
  			__func__, ip->i_ino,
  			ip->i_d.di_nextents + ip->i_d.di_anextents,
  			ip->i_d.di_nblocks, ip);
  		goto corrupt_out;
  	}
  	if (XFS_TEST_ERROR(ip->i_d.di_forkoff > mp->m_sb.sb_inodesize,
  				mp, XFS_ERRTAG_IFLUSH_6)) {
  		xfs_alert_tag(mp, XFS_PTAG_IFLUSH,
  			"%s: bad inode %Lu, forkoff 0x%x, ptr "PTR_FMT,
  			__func__, ip->i_ino, ip->i_d.di_forkoff, ip);
  		goto corrupt_out;
  	}
  
  	/*
  	 * Inode item log recovery for v2 inodes are dependent on the
  	 * di_flushiter count for correct sequencing. We bump the flush
  	 * iteration count so we can detect flushes which postdate a log record
  	 * during recovery. This is redundant as we now log every change and
  	 * hence this can't happen but we need to still do it to ensure
  	 * backwards compatibility with old kernels that predate logging all
  	 * inode changes.
  	 */
  	if (!xfs_sb_version_has_v3inode(&mp->m_sb))
  		ip->i_d.di_flushiter++;
  
  	/* Check the inline fork data before we write out. */
  	if (!xfs_inode_verify_forks(ip))
  		goto corrupt_out;
  
  	/*
  	 * Copy the dirty parts of the inode into the on-disk inode.  We always
  	 * copy out the core of the inode, because if the inode is dirty at all
  	 * the core must be.
  	 */
  	xfs_inode_to_disk(ip, dip, iip->ili_item.li_lsn);
  
  	/* Wrap, we never let the log put out DI_MAX_FLUSH */
  	if (ip->i_d.di_flushiter == DI_MAX_FLUSH)
  		ip->i_d.di_flushiter = 0;
  
  	xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
  	if (XFS_IFORK_Q(ip))
  		xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);
  	xfs_inobp_check(mp, bp);
  
  	/*
  	 * We've recorded everything logged in the inode, so we'd like to clear
  	 * the ili_fields bits so we don't log and flush things unnecessarily.
  	 * However, we can't stop logging all this information until the data
  	 * we've copied into the disk buffer is written to disk.  If we did we
  	 * might overwrite the copy of the inode in the log with all the data
  	 * after re-logging only part of it, and in the face of a crash we
  	 * wouldn't have all the data we need to recover.
  	 *
  	 * What we do is move the bits to the ili_last_fields field.  When
  	 * logging the inode, these bits are moved back to the ili_fields field.
  	 * In the xfs_iflush_done() routine we clear ili_last_fields, since we
  	 * know that the information those bits represent is permanently on
  	 * disk.  As long as the flush completes before the inode is logged
  	 * again, then both ili_fields and ili_last_fields will be cleared.
  	 *
  	 * We can play with the ili_fields bits here, because the inode lock
  	 * must be held exclusively in order to set bits there and the flush
  	 * lock protects the ili_last_fields bits.  Set ili_logged so the flush
  	 * done routine can tell whether or not to look in the AIL.  Also, store
  	 * the current LSN of the inode so that we can tell whether the item has
  	 * moved in the AIL from xfs_iflush_done().  In order to read the lsn we
  	 * need the AIL lock, because it is a 64 bit value that cannot be read
  	 * atomically.
  	 */
  	iip->ili_last_fields = iip->ili_fields;
  	iip->ili_fields = 0;
  	iip->ili_fsync_fields = 0;
  	iip->ili_logged = 1;
  
  	xfs_trans_ail_copy_lsn(mp->m_ail, &iip->ili_flush_lsn,
  				&iip->ili_item.li_lsn);
  
  	/*
  	 * Attach the function xfs_iflush_done to the inode's
  	 * buffer.  This will remove the inode from the AIL
  	 * and unlock the inode's flush lock when the inode is
  	 * completely written to disk.
  	 */
  	xfs_buf_attach_iodone(bp, xfs_iflush_done, &iip->ili_item);
  
  	/* generate the checksum. */
  	xfs_dinode_calc_crc(mp, dip);
  
  	ASSERT(!list_empty(&bp->b_li_list));
  	ASSERT(bp->b_iodone != NULL);
  	return 0;
  
  corrupt_out:
  	return -EFSCORRUPTED;
  }
  
  /* Release an inode. */
  void
  xfs_irele(
  	struct xfs_inode	*ip)
  {
  	trace_xfs_irele(ip, _RET_IP_);
  	iput(VFS_I(ip));
  }
  
  /*
   * Ensure all commited transactions touching the inode are written to the log.
   */
  int
  xfs_log_force_inode(
  	struct xfs_inode	*ip)
  {
  	xfs_lsn_t		lsn = 0;
  
  	xfs_ilock(ip, XFS_ILOCK_SHARED);
  	if (xfs_ipincount(ip))
  		lsn = ip->i_itemp->ili_last_lsn;
  	xfs_iunlock(ip, XFS_ILOCK_SHARED);
  
  	if (!lsn)
  		return 0;
  	return xfs_log_force_lsn(ip->i_mount, lsn, XFS_LOG_SYNC, NULL);
  }
  