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Fix deadlock between xfs_finish_reclaim and xfs_iget_core. An inode being
reclaimed and removed from memory by one thread while another thread
is attempting to reuse the inode and bring it back to life. There
was a window between the iget starting to reuse the inode and the
reclaim starting. Close the window by marking the inode as being
reused under the hash lock, and by abandoning the reclaim if this
is detected when it obtains the hash lock.
When a candidate inode is found in xfs_iget_core which has the potential
to be reclaimed, remove the XFS_IRECLAIMABLE flag under the inode hash
lock.

/*
 * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */

#include "xfs.h"

#include "xfs_macros.h"
#include "xfs_types.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_attr_sf.h"
#include "xfs_dir_sf.h"
#include "xfs_dir2_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_quota.h"
#include "xfs_utils.h"

/*
 * Initialize the inode hash table for the newly mounted file system.
 *
 * mp -- this is the mount point structure for the file system being
 *       initialized
 */
void
xfs_ihash_init(xfs_mount_t *mp)
{
	int	i;

	mp->m_ihsize = XFS_BUCKETS(mp);
	mp->m_ihash = (xfs_ihash_t *)kmem_zalloc(mp->m_ihsize
				      * sizeof(xfs_ihash_t), KM_SLEEP);
	ASSERT(mp->m_ihash != NULL);
	for (i = 0; i < mp->m_ihsize; i++) {
		rwlock_init(&(mp->m_ihash[i].ih_lock));
	}
}

/*
 * Free up structures allocated by xfs_ihash_init, at unmount time.
 */
void
xfs_ihash_free(xfs_mount_t *mp)
{
	kmem_free(mp->m_ihash, mp->m_ihsize*sizeof(xfs_ihash_t));
	mp->m_ihash = NULL;
}

/*
 * Initialize the inode cluster hash table for the newly mounted file system.
 *
 * mp -- this is the mount point structure for the file system being
 *       initialized
 */
void
xfs_chash_init(xfs_mount_t *mp)
{
	int	i;

	/*
	 * m_chash size is based on m_ihash
	 * with a minimum of 37 entries
	 */
	mp->m_chsize = (XFS_BUCKETS(mp)) /
			 (XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog);
	if (mp->m_chsize < 37) {
		mp->m_chsize = 37;
	}
	mp->m_chash = (xfs_chash_t *)kmem_zalloc(mp->m_chsize
						 * sizeof(xfs_chash_t),
						 KM_SLEEP);
	ASSERT(mp->m_chash != NULL);

	for (i = 0; i < mp->m_chsize; i++) {
		spinlock_init(&mp->m_chash[i].ch_lock,"xfshash");
	}
}

/*
 * Free up structures allocated by xfs_chash_init, at unmount time.
 */
void
xfs_chash_free(xfs_mount_t *mp)
{
	int	i;

	for (i = 0; i < mp->m_chsize; i++) {
		spinlock_destroy(&mp->m_chash[i].ch_lock);
	}

	kmem_free(mp->m_chash, mp->m_chsize*sizeof(xfs_chash_t));
	mp->m_chash = NULL;
}

/*
 * Look up an inode by number in the given file system.
 * The inode is looked up in the hash table for the file system
 * represented by the mount point parameter mp.  Each bucket of
 * the hash table is guarded by an individual semaphore.
 *
 * If the inode is found in the hash table, its corresponding vnode
 * is obtained with a call to vn_get().  This call takes care of
 * coordination with the reclamation of the inode and vnode.  Note
 * that the vmap structure is filled in while holding the hash lock.
 * This gives us the state of the inode/vnode when we found it and
 * is used for coordination in vn_get().
 *
 * If it is not in core, read it in from the file system's device and
 * add the inode into the hash table.
 *
 * The inode is locked according to the value of the lock_flags parameter.
 * This flag parameter indicates how and if the inode's IO lock and inode lock
 * should be taken.
 *
 * mp -- the mount point structure for the current file system.  It points
 *       to the inode hash table.
 * tp -- a pointer to the current transaction if there is one.  This is
 *       simply passed through to the xfs_iread() call.
 * ino -- the number of the inode desired.  This is the unique identifier
 *        within the file system for the inode being requested.
 * lock_flags -- flags indicating how to lock the inode.  See the comment
 *		 for xfs_ilock() for a list of valid values.
 * bno -- the block number starting the buffer containing the inode,
 *	  if known (as by bulkstat), else 0.
 */
STATIC int
xfs_iget_core(
	vnode_t		*vp,
	xfs_mount_t	*mp,
	xfs_trans_t	*tp,
	xfs_ino_t	ino,
	uint		lock_flags,
	xfs_inode_t	**ipp,
	xfs_daddr_t	bno)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*ip;
	xfs_inode_t	*iq;
	vnode_t		*inode_vp;
	ulong		version;
	int		error;
	/* REFERENCED */
	int		newnode;
	xfs_chash_t	*ch;
	xfs_chashlist_t	*chl, *chlnew;
	SPLDECL(s);


	ih = XFS_IHASH(mp, ino);

again:
	read_lock(&ih->ih_lock);

	for (ip = ih->ih_next; ip != NULL; ip = ip->i_next) {
		if (ip->i_ino == ino) {

			inode_vp = XFS_ITOV_NULL(ip);

			if (inode_vp == NULL) {
				/* If IRECLAIM is set this inode is
				 * on its way out of the system,
				 * we need to pause and try again.
				 */
				if (ip->i_flags & XFS_IRECLAIM) {
					read_unlock(&ih->ih_lock);
					delay(1);
					XFS_STATS_INC(xfsstats.xs_ig_frecycle);

					goto again;
				}

				vn_trace_exit(vp, "xfs_iget.alloc",
					(inst_t *)__return_address);

				XFS_STATS_INC(xfsstats.xs_ig_found);

				ip->i_flags &= ~XFS_IRECLAIMABLE;
				read_unlock(&ih->ih_lock);

				XFS_MOUNT_ILOCK(mp);
				list_del_init(&ip->i_reclaim);
				XFS_MOUNT_IUNLOCK(mp);

				goto finish_inode;

			} else if (vp != inode_vp) {
				struct inode *inode = LINVFS_GET_IP(inode_vp);

				/* The inode is being torn down, pause and
				 * try again.
				 */
				if (inode->i_state & (I_FREEING | I_CLEAR)) {
					read_unlock(&ih->ih_lock);
					delay(1);
					XFS_STATS_INC(xfsstats.xs_ig_frecycle);

					goto again;
				}
/* Chances are the other vnode (the one in the inode) is being torn
 * down right now, and we landed on top of it. Question is, what do
 * we do? Unhook the old inode and hook up the new one?
 */
				cmn_err(CE_PANIC,
			"xfs_iget_core: ambiguous vns: vp/0x%p, invp/0x%p",
						inode_vp, vp);
			}

			read_unlock(&ih->ih_lock);

			XFS_STATS_INC(xfsstats.xs_ig_found);

finish_inode:
			if (lock_flags != 0) {
				xfs_ilock(ip, lock_flags);
			}

			newnode = (ip->i_d.di_mode == 0);
			if (newnode) {
				xfs_iocore_inode_reinit(ip);
			}

			vn_trace_exit(vp, "xfs_iget.found",
						(inst_t *)__return_address);
			goto return_ip;
		}
	}

	/*
	 * Inode cache miss: save the hash chain version stamp and unlock
	 * the chain, so we don't deadlock in vn_alloc.
	 */
	XFS_STATS_INC(xfsstats.xs_ig_missed);

	version = ih->ih_version;

	read_unlock(&ih->ih_lock);

	/*
	 * Read the disk inode attributes into a new inode structure and get
	 * a new vnode for it. This should also initialize i_ino and i_mount.
	 */
	error = xfs_iread(mp, tp, ino, &ip, bno);
	if (error) {
		return error;
	}

	vn_trace_exit(vp, "xfs_iget.alloc", (inst_t *)__return_address);

	xfs_inode_lock_init(ip, vp);
	xfs_iocore_inode_init(ip);

	if (lock_flags != 0) {
		xfs_ilock(ip, lock_flags);
	}

	/*
	 * Put ip on its hash chain, unless someone else hashed a duplicate
	 * after we released the hash lock.
	 */
	write_lock(&ih->ih_lock);

	if (ih->ih_version != version) {
		for (iq = ih->ih_next; iq != NULL; iq = iq->i_next) {
			if (iq->i_ino == ino) {
				write_unlock(&ih->ih_lock);
				xfs_idestroy(ip);

				XFS_STATS_INC(xfsstats.xs_ig_dup);
				goto again;
			}
		}
	}

	/*
	 * These values _must_ be set before releasing ihlock!
	 */
	ip->i_hash = ih;
	if ((iq = ih->ih_next)) {
		iq->i_prevp = &ip->i_next;
	}
	ip->i_next = iq;
	ip->i_prevp = &ih->ih_next;
	ih->ih_next = ip;
	ip->i_udquot = ip->i_gdquot = NULL;
	ih->ih_version++;

	write_unlock(&ih->ih_lock);

	/*
	 * put ip on its cluster's hash chain
	 */
	ASSERT(ip->i_chash == NULL && ip->i_cprev == NULL &&
	       ip->i_cnext == NULL);

	chlnew = NULL;
	ch = XFS_CHASH(mp, ip->i_blkno);
 chlredo:
	s = mutex_spinlock(&ch->ch_lock);
	for (chl = ch->ch_list; chl != NULL; chl = chl->chl_next) {
		if (chl->chl_blkno == ip->i_blkno) {

			/* insert this inode into the doubly-linked list
			 * where chl points */
			if ((iq = chl->chl_ip)) {
				ip->i_cprev = iq->i_cprev;
				iq->i_cprev->i_cnext = ip;
				iq->i_cprev = ip;
				ip->i_cnext = iq;
			} else {
				ip->i_cnext = ip;
				ip->i_cprev = ip;
			}
			chl->chl_ip = ip;
			ip->i_chash = chl;
			break;
		}
	}

	/* no hash list found for this block; add a new hash list */
	if (chl == NULL)  {
		if (chlnew == NULL) {
			mutex_spinunlock(&ch->ch_lock, s);
			ASSERT(xfs_chashlist_zone != NULL);
			chlnew = (xfs_chashlist_t *)
					kmem_zone_alloc(xfs_chashlist_zone,
						KM_SLEEP);
			ASSERT(chlnew != NULL);
			goto chlredo;
		} else {
			ip->i_cnext = ip;
			ip->i_cprev = ip;
			ip->i_chash = chlnew;
			chlnew->chl_ip = ip;
			chlnew->chl_blkno = ip->i_blkno;
			chlnew->chl_next = ch->ch_list;
			ch->ch_list = chlnew;
			chlnew = NULL;
		}
	} else {
		if (chlnew != NULL) {
			kmem_zone_free(xfs_chashlist_zone, chlnew);
		}
	}

	mutex_spinunlock(&ch->ch_lock, s);


	/*
	 * Link ip to its mount and thread it on the mount's inode list.
	 */
	XFS_MOUNT_ILOCK(mp);
	if ((iq = mp->m_inodes)) {
		ASSERT(iq->i_mprev->i_mnext == iq);
		ip->i_mprev = iq->i_mprev;
		iq->i_mprev->i_mnext = ip;
		iq->i_mprev = ip;
		ip->i_mnext = iq;
	} else {
		ip->i_mnext = ip;
		ip->i_mprev = ip;
	}
	mp->m_inodes = ip;

	XFS_MOUNT_IUNLOCK(mp);

	newnode = 1;

 return_ip:
	ASSERT(ip->i_df.if_ext_max ==
	       XFS_IFORK_DSIZE(ip) / sizeof(xfs_bmbt_rec_t));

	ASSERT(((ip->i_d.di_flags & XFS_DIFLAG_REALTIME) != 0) ==
	       ((ip->i_iocore.io_flags & XFS_IOCORE_RT) != 0));

	*ipp = ip;

	/*
	 * If we have a real type for an on-disk inode, we can set ops(&unlock)
	 * now.	 If it's a new inode being created, xfs_ialloc will handle it.
	 */
	VFS_INIT_VNODE(XFS_MTOVFS(mp), vp, XFS_ITOBHV(ip), 1);

	return 0;
}


/*
 * The 'normal' internal xfs_iget, if needed it will
 * 'allocate', or 'get', the vnode.
 */
int
xfs_iget(
	xfs_mount_t	*mp,
	xfs_trans_t	*tp,
	xfs_ino_t	ino,
	uint		lock_flags,
	xfs_inode_t	**ipp,
	xfs_daddr_t	bno)
{
	struct inode	*inode;
	vnode_t		*vp = NULL;
	int		error;

retry:
	XFS_STATS_INC(xfsstats.xs_ig_attempts);

	if ((inode = VFS_GET_INODE(XFS_MTOVFS(mp), ino, 0))) {
		bhv_desc_t	*bdp;
		xfs_inode_t	*ip;
		int		newnode;

		vp = LINVFS_GET_VP(inode);
		if (inode->i_state & I_NEW) {
inode_allocate:
			vn_initialize(inode);
			error = xfs_iget_core(vp, mp, tp, ino,
						lock_flags, ipp, bno);
			if (error) {
				remove_inode_hash(inode);
				make_bad_inode(inode);
				if (inode->i_state & I_NEW)
					unlock_new_inode(inode);
				iput(inode);
			}
		} else {
			/* These are true if the inode is in inactive or
			 * reclaim. The linux inode is about to go away,
			 * wait for that path to finish, and try again.
			 */
			if (vp->v_flag & (VINACT | VRECLM)) {
				vn_wait(vp);
				iput(inode);
				goto retry;
			}

			if (is_bad_inode(inode)) {
				iput(inode);
				return EIO;
			}

			bdp = vn_bhv_lookup(VN_BHV_HEAD(vp), &xfs_vnodeops);
			if (bdp == NULL) {
				XFS_STATS_INC(xfsstats.xs_ig_dup);
				goto inode_allocate;
			}
			ip = XFS_BHVTOI(bdp);
			if (lock_flags != 0)
				xfs_ilock(ip, lock_flags);
			newnode = (ip->i_d.di_mode == 0);
			if (newnode)
				xfs_iocore_inode_reinit(ip);
			XFS_STATS_INC(xfsstats.xs_ig_found);
			*ipp = ip;
			error = 0;
		}
	} else
		error = ENOMEM;	/* If we got no inode we are out of memory */

	return error;
}

/*
 * Do the setup for the various locks within the incore inode.
 */
void
xfs_inode_lock_init(
	xfs_inode_t	*ip,
	vnode_t		*vp)
{
	mrlock_init(&ip->i_lock, MRLOCK_ALLOW_EQUAL_PRI|MRLOCK_BARRIER,
		     "xfsino", (long)vp->v_number);
	mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", vp->v_number);
#ifdef NOTYET
	mutex_init(&ip->i_range_lock.r_spinlock, MUTEX_SPIN, "xrange");
#endif /* NOTYET */
	init_waitqueue_head(&ip->i_ipin_wait);
	atomic_set(&ip->i_pincount, 0);
	init_sema(&ip->i_flock, 1, "xfsfino", vp->v_number);
}

/*
 * Look for the inode corresponding to the given ino in the hash table.
 * If it is there and its i_transp pointer matches tp, return it.
 * Otherwise, return NULL.
 */
xfs_inode_t *
xfs_inode_incore(xfs_mount_t	*mp,
		 xfs_ino_t	ino,
		 xfs_trans_t	*tp)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*ip;

	ih = XFS_IHASH(mp, ino);
	read_lock(&ih->ih_lock);
	for (ip = ih->ih_next; ip != NULL; ip = ip->i_next) {
		if (ip->i_ino == ino) {
			/*
			 * If we find it and tp matches, return it.
			 * Otherwise break from the loop and return
			 * NULL.
			 */
			if (ip->i_transp == tp) {
				read_unlock(&ih->ih_lock);
				return (ip);
			}
			break;
		}
	}
	read_unlock(&ih->ih_lock);
	return (NULL);
}

/*
 * Decrement reference count of an inode structure and unlock it.
 *
 * ip -- the inode being released
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be released.  See the comment on xfs_iunlock() for a list
 *	 of valid values.
 */
void
xfs_iput(xfs_inode_t	*ip,
	 uint		lock_flags)
{
	vnode_t	*vp = XFS_ITOV(ip);

	vn_trace_entry(vp, "xfs_iput", (inst_t *)__return_address);

	xfs_iunlock(ip, lock_flags);

	VN_RELE(vp);
}

/*
 * Special iput for brand-new inodes that are still locked
 */
void
xfs_iput_new(xfs_inode_t	*ip,
	     uint		lock_flags)
{
	vnode_t		*vp = XFS_ITOV(ip);
	struct inode	*inode = LINVFS_GET_IP(vp);

	vn_trace_entry(vp, "xfs_iput_new", (inst_t *)__return_address);

	/* We shouldn't get here without this being true, but just in case */
	if (inode->i_state & I_NEW) {
		remove_inode_hash(inode);
		make_bad_inode(inode);
		unlock_new_inode(inode);
	}
	if (lock_flags)
		xfs_iunlock(ip, lock_flags);
	VN_RELE(vp);
}


/*
 * This routine embodies the part of the reclaim code that pulls
 * the inode from the inode hash table and the mount structure's
 * inode list.
 * This should only be called from xfs_reclaim().
 */
void
xfs_ireclaim(xfs_inode_t *ip)
{
	vnode_t		*vp;

	/*
	 * Remove from old hash list and mount list.
	 */
	XFS_STATS_INC(xfsstats.xs_ig_reclaims);

	xfs_iextract(ip);

	/*
	 * Here we do a spurious inode lock in order to coordinate with
	 * xfs_sync().  This is because xfs_sync() references the inodes
	 * in the mount list without taking references on the corresponding
	 * vnodes.  We make that OK here by ensuring that we wait until
	 * the inode is unlocked in xfs_sync() before we go ahead and
	 * free it.  We get both the regular lock and the io lock because
	 * the xfs_sync() code may need to drop the regular one but will
	 * still hold the io lock.
	 */
	xfs_ilock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

	/*
	 * Release dquots (and their references) if any. An inode may escape
	 * xfs_inactive and get here via vn_alloc->vn_reclaim path.
	 */
	XFS_QM_DQDETACH(ip->i_mount, ip);

	/*
	 * Pull our behavior descriptor from the vnode chain.
	 */
	vp = XFS_ITOV_NULL(ip);
	if (vp) {
		vn_bhv_remove(VN_BHV_HEAD(vp), XFS_ITOBHV(ip));
	}

	/*
	 * Free all memory associated with the inode.
	 */
	xfs_idestroy(ip);
}

/*
 * This routine removes an about-to-be-destroyed inode from
 * all of the lists in which it is located with the exception
 * of the behavior chain.
 */
void
xfs_iextract(
	xfs_inode_t	*ip)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*iq;
	xfs_mount_t	*mp;
	xfs_chash_t	*ch;
	xfs_chashlist_t *chl, *chm;
	SPLDECL(s);

	ih = ip->i_hash;
	write_lock(&ih->ih_lock);
	if ((iq = ip->i_next)) {
		iq->i_prevp = ip->i_prevp;
	}
	*ip->i_prevp = iq;
	write_unlock(&ih->ih_lock);

	/*
	 * Remove from cluster hash list
	 *   1) delete the chashlist if this is the last inode on the chashlist
	 *   2) unchain from list of inodes
	 *   3) point chashlist->chl_ip to 'chl_next' if to this inode.
	 */
	mp = ip->i_mount;
	ch = XFS_CHASH(mp, ip->i_blkno);
	s = mutex_spinlock(&ch->ch_lock);

	if (ip->i_cnext == ip) {
		/* Last inode on chashlist */
		ASSERT(ip->i_cnext == ip && ip->i_cprev == ip);
		ASSERT(ip->i_chash != NULL);
		chm=NULL;
		for (chl = ch->ch_list; chl != NULL; chl = chl->chl_next) {
			if (chl->chl_blkno == ip->i_blkno) {
				if (chm == NULL) {
					/* first item on the list */
					ch->ch_list = chl->chl_next;
				} else {
					chm->chl_next = chl->chl_next;
				}
				kmem_zone_free(xfs_chashlist_zone, chl);
				break;
			} else {
				ASSERT(chl->chl_ip != ip);
				chm = chl;
			}
		}
		ASSERT_ALWAYS(chl != NULL);
       } else {
		/* delete one inode from a non-empty list */
		iq = ip->i_cnext;
		iq->i_cprev = ip->i_cprev;
		ip->i_cprev->i_cnext = iq;
		if (ip->i_chash->chl_ip == ip) {
			ip->i_chash->chl_ip = iq;
		}
		ip->i_chash = __return_address;
		ip->i_cprev = __return_address;
		ip->i_cnext = __return_address;
	}
	mutex_spinunlock(&ch->ch_lock, s);

	/*
	 * Remove from mount's inode list.
	 */
	XFS_MOUNT_ILOCK(mp);
	ASSERT((ip->i_mnext != NULL) && (ip->i_mprev != NULL));
	iq = ip->i_mnext;
	iq->i_mprev = ip->i_mprev;
	ip->i_mprev->i_mnext = iq;

	/*
	 * Fix up the head pointer if it points to the inode being deleted.
	 */
	if (mp->m_inodes == ip) {
		if (ip == iq) {
			mp->m_inodes = NULL;
		} else {
			mp->m_inodes = iq;
		}
	}

	/* Deal with the deleted inodes list */
	list_del_init(&ip->i_reclaim);

	mp->m_ireclaims++;
	XFS_MOUNT_IUNLOCK(mp);
}

/*
 * This is a wrapper routine around the xfs_ilock() routine
 * used to centralize some grungy code.  It is used in places
 * that wish to lock the inode solely for reading the extents.
 * The reason these places can't just call 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 function returns a value which should be given to the
 * corresponding xfs_iunlock_map_shared().  This value is
 * the mode in which the lock was actually taken.
 */
uint
xfs_ilock_map_shared(
	xfs_inode_t	*ip)
{
	uint	lock_mode;

	if ((ip->i_d.di_format == XFS_DINODE_FMT_BTREE) &&
	    ((ip->i_df.if_flags & XFS_IFEXTENTS) == 0)) {
		lock_mode = XFS_ILOCK_EXCL;
	} else {
		lock_mode = XFS_ILOCK_SHARED;
	}

	xfs_ilock(ip, lock_mode);

	return lock_mode;
}

/*
 * This is simply the unlock routine to go with xfs_ilock_map_shared().
 * All it does is call xfs_iunlock() with the given lock_mode.
 */
void
xfs_iunlock_map_shared(
	xfs_inode_t	*ip,
	unsigned int	lock_mode)
{
	xfs_iunlock(ip, lock_mode);
}

/*
 * The xfs inode contains 2 locks: a multi-reader lock called the
 * i_iolock and a multi-reader lock called the i_lock.  This routine
 * allows either or both of the locks to be obtained.
 *
 * The 2 locks should always be ordered so that the IO lock is
 * obtained first in order to prevent deadlock.
 *
 * ip -- the inode being locked
 * lock_flags -- this parameter indicates the inode's locks
 *       to be locked.  It can be:
 *		XFS_IOLOCK_SHARED,
 *		XFS_IOLOCK_EXCL,
 *		XFS_ILOCK_SHARED,
 *		XFS_ILOCK_EXCL,
 *		XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED,
 *		XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL,
 *		XFS_IOLOCK_EXCL | XFS_ILOCK_SHARED,
 *		XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
 */
void
xfs_ilock(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_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
	ASSERT((lock_flags & ~XFS_LOCK_MASK) == 0);

	if (lock_flags & XFS_IOLOCK_EXCL) {
		mrupdate(&ip->i_iolock);
	} else if (lock_flags & XFS_IOLOCK_SHARED) {
		mraccess(&ip->i_iolock);
	}
	if (lock_flags & XFS_ILOCK_EXCL) {
		mrupdate(&ip->i_lock);
	} else if (lock_flags & XFS_ILOCK_SHARED) {
		mraccess(&ip->i_lock);
	}
#ifdef XFS_ILOCK_TRACE
	xfs_ilock_trace(ip, 1, lock_flags, (inst_t *)return_address);
#endif
}

/*
 * 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)
{
	int	iolocked;
	int	ilocked;

	/*
	 * 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_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
	ASSERT((lock_flags & ~XFS_LOCK_MASK) == 0);

	iolocked = 0;
	if (lock_flags & XFS_IOLOCK_EXCL) {
		iolocked = mrtryupdate(&ip->i_iolock);
		if (!iolocked) {
			return 0;
		}
	} else if (lock_flags & XFS_IOLOCK_SHARED) {
		iolocked = mrtryaccess(&ip->i_iolock);
		if (!iolocked) {
			return 0;
		}
	}
	if (lock_flags & XFS_ILOCK_EXCL) {
		ilocked = mrtryupdate(&ip->i_lock);
		if (!ilocked) {
			if (iolocked) {
				mrunlock(&ip->i_iolock);
			}
			return 0;
		}
	} else if (lock_flags & XFS_ILOCK_SHARED) {
		ilocked = mrtryaccess(&ip->i_lock);
		if (!ilocked) {
			if (iolocked) {
				mrunlock(&ip->i_iolock);
			}
			return 0;
		}
	}
#ifdef XFS_ILOCK_TRACE
	xfs_ilock_trace(ip, 2, lock_flags, (inst_t *)__return_address);
#endif
	return 1;
}

/*
 * 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_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_IUNLOCK_NONOTIFY)) == 0);
	ASSERT(lock_flags != 0);

	if (lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) {
		ASSERT(!(lock_flags & XFS_IOLOCK_SHARED) ||
		       (ismrlocked(&ip->i_iolock, MR_ACCESS)));
		ASSERT(!(lock_flags & XFS_IOLOCK_EXCL) ||
		       (ismrlocked(&ip->i_iolock, MR_UPDATE)));
		mrunlock(&ip->i_iolock);
	}

	if (lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) {
		ASSERT(!(lock_flags & XFS_ILOCK_SHARED) ||
		       (ismrlocked(&ip->i_lock, MR_ACCESS)));
		ASSERT(!(lock_flags & XFS_ILOCK_EXCL) ||
		       (ismrlocked(&ip->i_lock, MR_UPDATE)));
		mrunlock(&ip->i_lock);

		/*
		 * Let the AIL know that this item has been unlocked in case
		 * it is in the AIL and anyone is waiting on it.  Don't do
		 * this if the caller has asked us not to.
		 */
		if (!(lock_flags & XFS_IUNLOCK_NONOTIFY) &&
		     ip->i_itemp != NULL) {
			xfs_trans_unlocked_item(ip->i_mount,
						(xfs_log_item_t*)(ip->i_itemp));
		}
	}
#ifdef XFS_ILOCK_TRACE
	xfs_ilock_trace(ip, 3, lock_flags, (inst_t *)__return_address);
#endif
}

/*
 * 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_ILOCK_EXCL));
	ASSERT((lock_flags & ~(XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);

	if (lock_flags & XFS_ILOCK_EXCL) {
		ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE));
		mrdemote(&ip->i_lock);
	}
	if (lock_flags & XFS_IOLOCK_EXCL) {
		ASSERT(ismrlocked(&ip->i_iolock, MR_UPDATE));
		mrdemote(&ip->i_iolock);
	}
}

/*
 * The following three routines simply manage the i_flock
 * semaphore embedded in the inode.  This semaphore synchronizes
 * processes attempting to flush the in-core inode back to disk.
 */
void
xfs_iflock(xfs_inode_t *ip)
{
	psema(&(ip->i_flock), PINOD|PLTWAIT);
}

int
xfs_iflock_nowait(xfs_inode_t *ip)
{
	return (cpsema(&(ip->i_flock)));
}

void
xfs_ifunlock(xfs_inode_t *ip)
{
	ASSERT(valusema(&(ip->i_flock)) <= 0);
	vsema(&(ip->i_flock));
}