x86: disable Voyager temporarily

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / xfs / xfs_iget.c

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_quota.h"
#include "xfs_utils.h"
#include "xfs_trans_priv.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_btree_trace.h"
#include "xfs_dir2_trace.h"


/*
 * Allocate and initialise an xfs_inode.
 */
STATIC struct xfs_inode *
xfs_inode_alloc(
        struct xfs_mount        *mp,
        xfs_ino_t               ino)
{
        struct xfs_inode        *ip;

        /*
         * if this didn't occur in transactions, we could use
         * KM_MAYFAIL and return NULL here on ENOMEM. Set the
         * code up to do this anyway.
         */
        ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
        if (!ip)
                return NULL;

        ASSERT(atomic_read(&ip->i_iocount) == 0);
        ASSERT(atomic_read(&ip->i_pincount) == 0);
        ASSERT(!spin_is_locked(&ip->i_flags_lock));
        ASSERT(completion_done(&ip->i_flush));

        /*
         * initialise the VFS inode here to get failures
         * out of the way early.
         */
        if (!inode_init_always(mp->m_super, VFS_I(ip))) {
                kmem_zone_free(xfs_inode_zone, ip);
                return NULL;
        }

        /* initialise the xfs inode */
        ip->i_ino = ino;
        ip->i_mount = mp;
        memset(&ip->i_imap, 0, sizeof(struct xfs_imap));
        ip->i_afp = NULL;
        memset(&ip->i_df, 0, sizeof(xfs_ifork_t));
        ip->i_flags = 0;
        ip->i_update_core = 0;
        ip->i_update_size = 0;
        ip->i_delayed_blks = 0;
        memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));
        ip->i_size = 0;
        ip->i_new_size = 0;

        /*
         * Initialize inode's trace buffers.
         */
#ifdef  XFS_INODE_TRACE
        ip->i_trace = ktrace_alloc(INODE_TRACE_SIZE, KM_NOFS);
#endif
#ifdef XFS_BMAP_TRACE
        ip->i_xtrace = ktrace_alloc(XFS_BMAP_KTRACE_SIZE, KM_NOFS);
#endif
#ifdef XFS_BTREE_TRACE
        ip->i_btrace = ktrace_alloc(XFS_BMBT_KTRACE_SIZE, KM_NOFS);
#endif
#ifdef XFS_RW_TRACE
        ip->i_rwtrace = ktrace_alloc(XFS_RW_KTRACE_SIZE, KM_NOFS);
#endif
#ifdef XFS_ILOCK_TRACE
        ip->i_lock_trace = ktrace_alloc(XFS_ILOCK_KTRACE_SIZE, KM_NOFS);
#endif
#ifdef XFS_DIR2_TRACE
        ip->i_dir_trace = ktrace_alloc(XFS_DIR2_KTRACE_SIZE, KM_NOFS);
#endif

        return ip;
}

/*
 * Check the validity of the inode we just found it the cache
 */
static int
xfs_iget_cache_hit(
        struct xfs_perag        *pag,
        struct xfs_inode        *ip,
        int                     flags,
        int                     lock_flags) __releases(pag->pag_ici_lock)
{
        struct xfs_mount        *mp = ip->i_mount;
        int                     error = EAGAIN;

        /*
         * If INEW is set this inode is being set up
         * If IRECLAIM is set this inode is being torn down
         * Pause and try again.
         */
        if (xfs_iflags_test(ip, (XFS_INEW|XFS_IRECLAIM))) {
                XFS_STATS_INC(xs_ig_frecycle);
                goto out_error;
        }

        /* If IRECLAIMABLE is set, we've torn down the vfs inode part */
        if (xfs_iflags_test(ip, XFS_IRECLAIMABLE)) {

                /*
                 * If lookup is racing with unlink, then we should return an
                 * error immediately so we don't remove it from the reclaim
                 * list and potentially leak the inode.
                 */
                if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
                        error = ENOENT;
                        goto out_error;
                }

                xfs_itrace_exit_tag(ip, "xfs_iget.alloc");

                /*
                 * We need to re-initialise the VFS inode as it has been
                 * 'freed' by the VFS. Do this here so we can deal with
                 * errors cleanly, then tag it so it can be set up correctly
                 * later.
                 */
                if (!inode_init_always(mp->m_super, VFS_I(ip))) {
                        error = ENOMEM;
                        goto out_error;
                }

                /*
                 * We must set the XFS_INEW flag before clearing the
                 * XFS_IRECLAIMABLE flag so that if a racing lookup does
                 * not find the XFS_IRECLAIMABLE above but has the igrab()
                 * below succeed we can safely check XFS_INEW to detect
                 * that this inode is still being initialised.
                 */
                xfs_iflags_set(ip, XFS_INEW);
                xfs_iflags_clear(ip, XFS_IRECLAIMABLE);

                /* clear the radix tree reclaim flag as well. */
                __xfs_inode_clear_reclaim_tag(mp, pag, ip);
        } else if (!igrab(VFS_I(ip))) {
                /* If the VFS inode is being torn down, pause and try again. */
                XFS_STATS_INC(xs_ig_frecycle);
                goto out_error;
        } else if (xfs_iflags_test(ip, XFS_INEW)) {
                /*
                 * We are racing with another cache hit that is
                 * currently recycling this inode out of the XFS_IRECLAIMABLE
                 * state. Wait for the initialisation to complete before
                 * continuing.
                 */
                wait_on_inode(VFS_I(ip));
        }

        if (ip->i_d.di_mode == 0 && !(flags & XFS_IGET_CREATE)) {
                error = ENOENT;
                iput(VFS_I(ip));
                goto out_error;
        }

        /* We've got a live one. */
        read_unlock(&pag->pag_ici_lock);

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

        xfs_iflags_clear(ip, XFS_ISTALE);
        xfs_itrace_exit_tag(ip, "xfs_iget.found");
        XFS_STATS_INC(xs_ig_found);
        return 0;

out_error:
        read_unlock(&pag->pag_ici_lock);
        return error;
}


static int
xfs_iget_cache_miss(
        struct xfs_mount        *mp,
        struct xfs_perag        *pag,
        xfs_trans_t             *tp,
        xfs_ino_t               ino,
        struct xfs_inode        **ipp,
        xfs_daddr_t             bno,
        int                     flags,
        int                     lock_flags) __releases(pag->pag_ici_lock)
{
        struct xfs_inode        *ip;
        int                     error;
        unsigned long           first_index, mask;
        xfs_agino_t             agino = XFS_INO_TO_AGINO(mp, ino);

        ip = xfs_inode_alloc(mp, ino);
        if (!ip)
                return ENOMEM;

        error = xfs_iread(mp, tp, ip, bno, flags);
        if (error)
                goto out_destroy;

        xfs_itrace_exit_tag(ip, "xfs_iget.alloc");

        if ((ip->i_d.di_mode == 0) && !(flags & XFS_IGET_CREATE)) {
                error = ENOENT;
                goto out_destroy;
        }

        if (lock_flags)
                xfs_ilock(ip, lock_flags);

        /*
         * Preload the radix tree so we can insert safely under the
         * write spinlock. Note that we cannot sleep inside the preload
         * region.
         */
        if (radix_tree_preload(GFP_KERNEL)) {
                error = EAGAIN;
                goto out_unlock;
        }

        mask = ~(((XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog)) - 1);
        first_index = agino & mask;
        write_lock(&pag->pag_ici_lock);

        /* insert the new inode */
        error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
        if (unlikely(error)) {
                WARN_ON(error != -EEXIST);
                XFS_STATS_INC(xs_ig_dup);
                error = EAGAIN;
                goto out_preload_end;
        }

        /* These values _must_ be set before releasing the radix tree lock! */
        ip->i_udquot = ip->i_gdquot = NULL;
        xfs_iflags_set(ip, XFS_INEW);

        write_unlock(&pag->pag_ici_lock);
        radix_tree_preload_end();
        *ipp = ip;
        return 0;

out_preload_end:
        write_unlock(&pag->pag_ici_lock);
        radix_tree_preload_end();
out_unlock:
        if (lock_flags)
                xfs_iunlock(ip, lock_flags);
out_destroy:
        xfs_destroy_inode(ip);
        return error;
}

/*
 * Look up an inode by number in the given file system.
 * The inode is looked up in the cache held in each AG.
 * If the inode is found in the cache, initialise the vfs inode
 * if necessary.
 *
 * If it is not in core, read it in from the file system's device,
 * add it to the cache and initialise the vfs inode.
 *
 * 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.
 */
int
xfs_iget(
        xfs_mount_t     *mp,
        xfs_trans_t     *tp,
        xfs_ino_t       ino,
        uint            flags,
        uint            lock_flags,
        xfs_inode_t     **ipp,
        xfs_daddr_t     bno)
{
        xfs_inode_t     *ip;
        int             error;
        xfs_perag_t     *pag;
        xfs_agino_t     agino;

        /* the radix tree exists only in inode capable AGs */
        if (XFS_INO_TO_AGNO(mp, ino) >= mp->m_maxagi)
                return EINVAL;

        /* get the perag structure and ensure that it's inode capable */
        pag = xfs_get_perag(mp, ino);
        if (!pag->pagi_inodeok)
                return EINVAL;
        ASSERT(pag->pag_ici_init);
        agino = XFS_INO_TO_AGINO(mp, ino);

again:
        error = 0;
        read_lock(&pag->pag_ici_lock);
        ip = radix_tree_lookup(&pag->pag_ici_root, agino);

        if (ip) {
                error = xfs_iget_cache_hit(pag, ip, flags, lock_flags);
                if (error)
                        goto out_error_or_again;
        } else {
                read_unlock(&pag->pag_ici_lock);
                XFS_STATS_INC(xs_ig_missed);

                error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip, bno,
                                                        flags, lock_flags);
                if (error)
                        goto out_error_or_again;
        }
        xfs_put_perag(mp, pag);

        *ipp = ip;

        ASSERT(ip->i_df.if_ext_max ==
               XFS_IFORK_DSIZE(ip) / sizeof(xfs_bmbt_rec_t));
        /*
         * 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.
         */
        if (xfs_iflags_test(ip, XFS_INEW) && ip->i_d.di_mode != 0)
                xfs_setup_inode(ip);
        return 0;

out_error_or_again:
        if (error == EAGAIN) {
                delay(1);
                goto again;
        }
        xfs_put_perag(mp, pag);
        return error;
}


/*
 * 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_inode_t     *ip;
        xfs_perag_t     *pag;

        pag = xfs_get_perag(mp, ino);
        read_lock(&pag->pag_ici_lock);
        ip = radix_tree_lookup(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ino));
        read_unlock(&pag->pag_ici_lock);
        xfs_put_perag(mp, pag);

        /* the returned inode must match the transaction */
        if (ip && (ip->i_transp != tp))
                return NULL;
        return ip;
}

/*
 * 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)
{
        xfs_itrace_entry(ip);
        xfs_iunlock(ip, lock_flags);
        IRELE(ip);
}

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

        xfs_itrace_entry(ip);

        if ((ip->i_d.di_mode == 0)) {
                ASSERT(!xfs_iflags_test(ip, XFS_IRECLAIMABLE));
                make_bad_inode(inode);
        }
        if (inode->i_state & I_NEW)
                unlock_new_inode(inode);
        if (lock_flags)
                xfs_iunlock(ip, lock_flags);
        IRELE(ip);
}

/*
 * This is called free all the memory associated with an inode.
 * It must free the inode itself and any buffers allocated for
 * if_extents/if_data and if_broot.  It must also free the lock
 * associated with the inode.
 *
 * Note: because we don't initialise everything on reallocation out
 * of the zone, we must ensure we nullify everything correctly before
 * freeing the structure.
 */
void
xfs_ireclaim(
        struct xfs_inode        *ip)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_perag        *pag;

        XFS_STATS_INC(xs_ig_reclaims);

        /*
         * Remove the inode from the per-AG radix tree.  It doesn't matter
         * if it was never added to it because radix_tree_delete can deal
         * with that case just fine.
         */
        pag = xfs_get_perag(mp, ip->i_ino);
        write_lock(&pag->pag_ici_lock);
        radix_tree_delete(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ip->i_ino));
        write_unlock(&pag->pag_ici_lock);
        xfs_put_perag(mp, pag);

        /*
         * Here we do an (almost) spurious inode lock in order to coordinate
         * with inode cache radix tree lookups.  This is because the lookup
         * can reference the inodes in the cache without taking references.
         *
         * We make that OK here by ensuring that we wait until the inode is
         * unlocked after the lookup before we go ahead and free it.  We get
         * both the ilock and the iolock because the code may need to drop the
         * ilock one but will still hold the iolock.
         */
        xfs_ilock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
        /*
         * Release dquots (and their references) if any.
         */
        XFS_QM_DQDETACH(ip->i_mount, ip);
        xfs_iunlock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

        switch (ip->i_d.di_mode & S_IFMT) {
        case S_IFREG:
        case S_IFDIR:
        case S_IFLNK:
                xfs_idestroy_fork(ip, XFS_DATA_FORK);
                break;
        }

        if (ip->i_afp)
                xfs_idestroy_fork(ip, XFS_ATTR_FORK);

#ifdef XFS_INODE_TRACE
        ktrace_free(ip->i_trace);
#endif
#ifdef XFS_BMAP_TRACE
        ktrace_free(ip->i_xtrace);
#endif
#ifdef XFS_BTREE_TRACE
        ktrace_free(ip->i_btrace);
#endif
#ifdef XFS_RW_TRACE
        ktrace_free(ip->i_rwtrace);
#endif
#ifdef XFS_ILOCK_TRACE
        ktrace_free(ip->i_lock_trace);
#endif
#ifdef XFS_DIR2_TRACE
        ktrace_free(ip->i_dir_trace);
#endif
        if (ip->i_itemp) {
                /*
                 * Only if we are shutting down the fs will we see an
                 * inode still in the AIL. If it is there, we should remove
                 * it to prevent a use-after-free from occurring.
                 */
                xfs_log_item_t  *lip = &ip->i_itemp->ili_item;
                struct xfs_ail  *ailp = lip->li_ailp;

                ASSERT(((lip->li_flags & XFS_LI_IN_AIL) == 0) ||
                                       XFS_FORCED_SHUTDOWN(ip->i_mount));
                if (lip->li_flags & XFS_LI_IN_AIL) {
                        spin_lock(&ailp->xa_lock);
                        if (lip->li_flags & XFS_LI_IN_AIL)
                                xfs_trans_ail_delete(ailp, lip);
                        else
                                spin_unlock(&ailp->xa_lock);
                }
                xfs_inode_item_destroy(ip);
                ip->i_itemp = NULL;
        }
        /* asserts to verify all state is correct here */
        ASSERT(atomic_read(&ip->i_iocount) == 0);
        ASSERT(atomic_read(&ip->i_pincount) == 0);
        ASSERT(!spin_is_locked(&ip->i_flags_lock));
        ASSERT(completion_done(&ip->i_flush));
        kmem_zone_free(xfs_inode_zone, ip);
}

/*
 * 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 | XFS_LOCK_DEP_MASK)) == 0);

        if (lock_flags & XFS_IOLOCK_EXCL)
                mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
        else if (lock_flags & XFS_IOLOCK_SHARED)
                mraccess_nested(&ip->i_iolock, XFS_IOLOCK_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));

        xfs_ilock_trace(ip, 1, lock_flags, (inst_t *)__return_address);
}

/*
 * 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)
{
        /*
         * 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_LOCK_DEP_MASK)) == 0);

        if (lock_flags & XFS_IOLOCK_EXCL) {
                if (!mrtryupdate(&ip->i_iolock))
                        goto out;
        } else if (lock_flags & XFS_IOLOCK_SHARED) {
                if (!mrtryaccess(&ip->i_iolock))
                        goto out;
        }
        if (lock_flags & XFS_ILOCK_EXCL) {
                if (!mrtryupdate(&ip->i_lock))
                        goto out_undo_iolock;
        } else if (lock_flags & XFS_ILOCK_SHARED) {
                if (!mrtryaccess(&ip->i_lock))
                        goto out_undo_iolock;
        }
        xfs_ilock_trace(ip, 2, lock_flags, (inst_t *)__return_address);
        return 1;

 out_undo_iolock:
        if (lock_flags & XFS_IOLOCK_EXCL)
                mrunlock_excl(&ip->i_iolock);
        else if (lock_flags & XFS_IOLOCK_SHARED)
                mrunlock_shared(&ip->i_iolock);
 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_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
               (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
        ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_IUNLOCK_NONOTIFY |
                        XFS_LOCK_DEP_MASK)) == 0);
        ASSERT(lock_flags != 0);

        if (lock_flags & XFS_IOLOCK_EXCL)
                mrunlock_excl(&ip->i_iolock);
        else if (lock_flags & XFS_IOLOCK_SHARED)
                mrunlock_shared(&ip->i_iolock);

        if (lock_flags & XFS_ILOCK_EXCL)
                mrunlock_excl(&ip->i_lock);
        else if (lock_flags & XFS_ILOCK_SHARED)
                mrunlock_shared(&ip->i_lock);

        if ((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) &&
            !(lock_flags & XFS_IUNLOCK_NONOTIFY) && ip->i_itemp) {
                /*
                 * 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.
                 */
                xfs_trans_unlocked_item(ip->i_itemp->ili_item.li_ailp,
                                        (xfs_log_item_t*)(ip->i_itemp));
        }
        xfs_ilock_trace(ip, 3, lock_flags, (inst_t *)__return_address);
}

/*
 * 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)
                mrdemote(&ip->i_lock);
        if (lock_flags & XFS_IOLOCK_EXCL)
                mrdemote(&ip->i_iolock);
}

#ifdef DEBUG
/*
 * Debug-only routine, without additional rw_semaphore APIs, we can
 * now only answer requests regarding whether we hold the lock for write
 * (reader state is outside our visibility, we only track writer state).
 *
 * Note: this means !xfs_isilocked would give false positives, so don't do that.
 */
int
xfs_isilocked(
        xfs_inode_t             *ip,
        uint                    lock_flags)
{
        if ((lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) ==
                        XFS_ILOCK_EXCL) {
                if (!ip->i_lock.mr_writer)
                        return 0;
        }

        if ((lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) ==
                        XFS_IOLOCK_EXCL) {
                if (!ip->i_iolock.mr_writer)
                        return 0;
        }

        return 1;
}
#endif

#ifdef  XFS_INODE_TRACE

#define KTRACE_ENTER(ip, vk, s, line, ra)                       \
        ktrace_enter((ip)->i_trace,                             \
/*  0 */                (void *)(__psint_t)(vk),                \
/*  1 */                (void *)(s),                            \
/*  2 */                (void *)(__psint_t) line,               \
/*  3 */                (void *)(__psint_t)atomic_read(&VFS_I(ip)->i_count), \
/*  4 */                (void *)(ra),                           \
/*  5 */                NULL,                                   \
/*  6 */                (void *)(__psint_t)current_cpu(),       \
/*  7 */                (void *)(__psint_t)current_pid(),       \
/*  8 */                (void *)__return_address,               \
/*  9 */                NULL, NULL, NULL, NULL, NULL, NULL, NULL)

/*
 * Vnode tracing code.
 */
void
_xfs_itrace_entry(xfs_inode_t *ip, const char *func, inst_t *ra)
{
        KTRACE_ENTER(ip, INODE_KTRACE_ENTRY, func, 0, ra);
}

void
_xfs_itrace_exit(xfs_inode_t *ip, const char *func, inst_t *ra)
{
        KTRACE_ENTER(ip, INODE_KTRACE_EXIT, func, 0, ra);
}

void
xfs_itrace_hold(xfs_inode_t *ip, char *file, int line, inst_t *ra)
{
        KTRACE_ENTER(ip, INODE_KTRACE_HOLD, file, line, ra);
}

void
_xfs_itrace_ref(xfs_inode_t *ip, char *file, int line, inst_t *ra)
{
        KTRACE_ENTER(ip, INODE_KTRACE_REF, file, line, ra);
}

void
xfs_itrace_rele(xfs_inode_t *ip, char *file, int line, inst_t *ra)
{
        KTRACE_ENTER(ip, INODE_KTRACE_RELE, file, line, ra);
}
#endif  /* XFS_INODE_TRACE */