[apple/xnu.git] / bsd / hfs / hfs_cnode.c

/*
 * Copyright (c) 2002-2012 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/time.h>
#include <sys/ubc.h>
#include <sys/quota.h>
#include <sys/kdebug.h>
#include <libkern/OSByteOrder.h>
#include <sys/buf_internal.h>

#include <kern/locks.h>

#include <miscfs/specfs/specdev.h>
#include <miscfs/fifofs/fifo.h>

#include <hfs/hfs.h>
#include <hfs/hfs_catalog.h>
#include <hfs/hfs_cnode.h>
#include <hfs/hfs_quota.h>
#include <hfs/hfs_format.h>

extern int prtactive;

extern lck_attr_t *  hfs_lock_attr;
extern lck_grp_t *  hfs_mutex_group;
extern lck_grp_t *  hfs_rwlock_group;

static void  hfs_reclaim_cnode(struct cnode *);
static int hfs_cnode_teardown (struct vnode *vp, vfs_context_t ctx, int reclaim);
static int hfs_isordered(struct cnode *, struct cnode *);

extern int hfs_removefile_callback(struct buf *bp, void *hfsmp);

__inline__ int hfs_checkdeleted (struct cnode *cp) {
        return ((cp->c_flag & (C_DELETED | C_NOEXISTS)) ? ENOENT : 0);  
}

/*
 * Function used by a special fcntl() that decorates a cnode/vnode that
 * indicates it is backing another filesystem, like a disk image.
 *
 * the argument 'val' indicates whether or not to set the bit in the cnode flags
 * 
 * Returns non-zero on failure. 0 on success 
 */
int hfs_set_backingstore (struct vnode *vp, int val) {
        struct cnode *cp = NULL;
        int err = 0;
        
        cp = VTOC(vp);
        if (!vnode_isreg(vp) && !vnode_isdir(vp)) {
                return EINVAL;
        }

        /* lock the cnode */
        err = hfs_lock (cp, HFS_EXCLUSIVE_LOCK);
        if (err) {
                return err;
        }
        
        if (val) {
                cp->c_flag |= C_BACKINGSTORE;
        }
        else {
                cp->c_flag &= ~C_BACKINGSTORE;
        }

        /* unlock everything */
        hfs_unlock (cp);

        return err;
}

/*
 * Function used by a special fcntl() that check to see if a cnode/vnode
 * indicates it is backing another filesystem, like a disk image.
 *
 * the argument 'val' is an output argument for whether or not the bit is set
 * 
 * Returns non-zero on failure. 0 on success 
 */

int hfs_is_backingstore (struct vnode *vp, int *val) {
        struct cnode *cp = NULL;
        int err = 0;

        if (!vnode_isreg(vp) && !vnode_isdir(vp)) {
                *val = 0;
                return 0;
        }

        cp = VTOC(vp);

        /* lock the cnode */
        err = hfs_lock (cp, HFS_SHARED_LOCK);
        if (err) {
                return err;
        }

        if (cp->c_flag & C_BACKINGSTORE) {
                *val = 1;
        }       
        else {
                *val = 0;
        }

        /* unlock everything */
        hfs_unlock (cp);

        return err;
}


/*
 * hfs_cnode_teardown
 *
 * This is an internal function that is invoked from both hfs_vnop_inactive
 * and hfs_vnop_reclaim.  As VNOP_INACTIVE is not necessarily called from vnodes
 * being recycled and reclaimed, it is important that we do any post-processing
 * necessary for the cnode in both places.  Important tasks include things such as
 * releasing the blocks from an open-unlinked file when all references to it have dropped,
 * and handling resource forks separately from data forks.
 *
 * Note that we take only the vnode as an argument here (rather than the cnode).
 * Recall that each cnode supports two forks (rsrc/data), and we can always get the right
 * cnode from either of the vnodes, but the reverse is not true -- we can't determine which
 * vnode we need to reclaim if only the cnode is supplied. 
 *
 * This function is idempotent and safe to call from both hfs_vnop_inactive and hfs_vnop_reclaim
 * if both are invoked right after the other.  In the second call, most of this function's if()
 * conditions will fail, since they apply generally to cnodes still marked with C_DELETED.  
 * As a quick check to see if this function is necessary, determine if the cnode is already
 * marked C_NOEXISTS.  If it is, then it is safe to skip this function.  The only tasks that 
 * remain for cnodes marked in such a fashion is to teardown their fork references and 
 * release all directory hints and hardlink origins.  However, both of those are done 
 * in hfs_vnop_reclaim.  hfs_update, by definition, is not necessary if the cnode's catalog
 * entry is no longer there.  
 *
 * 'reclaim' argument specifies whether or not we were called from hfs_vnop_reclaim.  If we are
 * invoked from hfs_vnop_reclaim, we can not call functions that cluster_push since the UBC info 
 * is totally gone by that point.
 *
 * Assumes that both truncate and cnode locks for 'cp' are held.
 */
static 
int hfs_cnode_teardown (struct vnode *vp, vfs_context_t ctx, int reclaim) {
        
        int forkcount = 0;
        enum vtype v_type;
        struct cnode *cp;
        int error = 0;
        int started_tr = 0;
        struct hfsmount *hfsmp = VTOHFS(vp);
        struct proc *p = vfs_context_proc(ctx);
        int truncated = 0;
    cat_cookie_t cookie;
    int cat_reserve = 0;
    int lockflags;
        int ea_error = 0;
        
        v_type = vnode_vtype(vp);
        cp = VTOC(vp);
        
        if (cp->c_datafork) {
                ++forkcount;
        }
        if (cp->c_rsrcfork) {
                ++forkcount;
        }
        
        
        /*
         * Skip the call to ubc_setsize if we're being invoked on behalf of reclaim.
         * The dirty regions would have already been synced to disk, so informing UBC
         * that they can toss the pages doesn't help anyone at this point. 
         * 
         * Note that this is a performance problem if the vnode goes straight to reclaim
         * (and skips inactive), since there would be no way for anyone to notify the UBC
         * that all pages in this file are basically useless.
         */     
        if (reclaim == 0) {
                /*
                 * Check whether we are tearing down a cnode with only one remaining fork.
                 * If there are blocks in its filefork, then we need to unlock the cnode
                 * before calling ubc_setsize.  The cluster layer may re-enter the filesystem
                 * (i.e. VNOP_BLOCKMAP), and if we retain the cnode lock, we could double-lock
                 * panic.  
                 */
                
                if ((v_type == VREG || v_type == VLNK) &&
                        (cp->c_flag & C_DELETED) &&
                        (VTOF(vp)->ff_blocks != 0) && (forkcount == 1)) {
                        hfs_unlock(cp); 
                        /* ubc_setsize just fails if we were to call this from VNOP_RECLAIM */
                        ubc_setsize(vp, 0);
                        (void) hfs_lock(cp, HFS_FORCE_LOCK);
                }       
        }
        
        /* 
         * Push file data out for normal files that haven't been evicted from 
         * the namespace.  We only do this if this function was not called from reclaim,
         * because by that point the UBC information has been totally torn down.  
         * 
         * There should also be no way that a normal file that has NOT been deleted from 
         * the namespace to skip INACTIVE and go straight to RECLAIM.  That race only happens
         * when the file becomes open-unlinked. 
         */
        if ((v_type == VREG) && 
                (!ISSET(cp->c_flag, C_DELETED)) && 
                (!ISSET(cp->c_flag, C_NOEXISTS)) &&
                (VTOF(vp)->ff_blocks) &&
                (reclaim == 0)) {
                /* 
                 * Note that if content protection is enabled, then this is where we will
                 * attempt to issue IOs for all dirty regions of this file.  
                 *
                 * If we're called from hfs_vnop_inactive, all this means is at the time 
                 * the logic for deciding to call this function, there were not any lingering
                 * mmap/fd references for this file.  However, there is nothing preventing the system
                 * from creating a new reference in between the time that logic was checked
                 * and we entered hfs_vnop_inactive.  As a result, the only time we can guarantee
                 * that there aren't any references is during vnop_reclaim.
                 */
                hfs_filedone(vp, ctx);
        }

        /* 
         * We're holding the cnode lock now.  Stall behind any shadow BPs that may
         * be involved with this vnode if it is a symlink.  We don't want to allow 
         * the blocks that we're about to release to be put back into the pool if there
         * is pending I/O to them.
         */
        if (v_type == VLNK) {   
                /* 
                 * This will block if the asynchronous journal flush is in progress.
                 * If this symlink is not being renamed over and doesn't have any open FDs,
                 * then we'll remove it from the journal's bufs below in kill_block.
                 */
                buf_wait_for_shadow_io (vp, 0);
        }

        /* 
         * Remove any directory hints or cached origins
         */
        if (v_type == VDIR) {
                hfs_reldirhints(cp, 0);
        }
        if (cp->c_flag & C_HARDLINK) {
                hfs_relorigins(cp);
        }
        
        /*
         * This check is slightly complicated.  We should only truncate data 
         * in very specific cases for open-unlinked files.  This is because
         * we want to ensure that the resource fork continues to be available
         * if the caller has the data fork open.  However, this is not symmetric; 
         * someone who has the resource fork open need not be able to access the data
         * fork once the data fork has gone inactive.
         * 
         * If we're the last fork, then we have cleaning up to do.
         * 
         * A) last fork, and vp == c_vp
         *      Truncate away own fork data. If rsrc fork is not in core, truncate it too.
         *
         * B) last fork, and vp == c_rsrc_vp
         *      Truncate ourselves, assume data fork has been cleaned due to C).
         *
         * If we're not the last fork, then things are a little different:
         *
         * C) not the last fork, vp == c_vp
         *      Truncate ourselves.  Once the file has gone out of the namespace,
         *      it cannot be further opened.  Further access to the rsrc fork may 
         *      continue, however.
         *
         * D) not the last fork, vp == c_rsrc_vp
         *      Don't enter the block below, just clean up vnode and push it out of core.
         */
        
        if ((v_type == VREG || v_type == VLNK) && 
                (cp->c_flag & C_DELETED) &&
                ((forkcount == 1) || (!VNODE_IS_RSRC(vp)))) {

                /* Start a transaction here.  We're about to change file sizes */
                if (started_tr == 0) {
                        if (hfs_start_transaction(hfsmp) != 0) {
                                error = EINVAL;
                                goto out;
                        }
                        else {
                                started_tr = 1;
                        }
                }
        
                /* Truncate away our own fork data. (Case A, B, C above) */
                if (VTOF(vp)->ff_blocks != 0) {
                        
                        /*
                         * At this point, we have decided that this cnode is
                         * suitable for full removal.  We are about to deallocate
                         * its blocks and remove its entry from the catalog. 
                         * If it was a symlink, then it's possible that the operation
                         * which created it is still in the current transaction group
                         * due to coalescing.  Take action here to kill the data blocks
                         * of the symlink out of the journal before moving to 
                         * deallocate the blocks.  We need to be in the middle of
                         * a transaction before calling buf_iterate like this.
                         * 
                         * Note: we have to kill any potential symlink buffers out of 
                         * the journal prior to deallocating their blocks.  This is so 
                         * that we don't race with another thread that may be doing an 
                         * an allocation concurrently and pick up these blocks. It could
                         * generate I/O against them which could go out ahead of our journal
                         * transaction.
                         */

                        if (hfsmp->jnl && vnode_islnk(vp)) {
                                buf_iterate(vp, hfs_removefile_callback, BUF_SKIP_NONLOCKED, (void *)hfsmp);
                        }

                        /*
                         * Since we're already inside a transaction,
                         * tell hfs_truncate to skip the ubc_setsize.
                         *
                         * This truncate call (and the one below) is fine from VNOP_RECLAIM's 
                         * context because we're only removing blocks, not zero-filling new 
                         * ones.  The C_DELETED check above makes things much simpler. 
                         */
                        error = hfs_truncate(vp, (off_t)0, IO_NDELAY, 1, 0, ctx);
                        if (error) {
                                goto out;
                        }
                        truncated = 1;
                }
                
                /* 
                 * Truncate away the resource fork, if we represent the data fork and
                 * it is the last fork.  That means, by definition, the rsrc fork is not in 
                 * core.  To avoid bringing a vnode into core for the sole purpose of deleting the
                 * data in the resource fork, we call cat_lookup directly, then hfs_release_storage
                 * to get rid of the resource fork's data. 
                 * 
                 * This is invoked via case A above only.
                 */
                if ((cp->c_blocks > 0) && (forkcount == 1) && (vp != cp->c_rsrc_vp)) {
                        struct cat_lookup_buffer *lookup_rsrc = NULL;
                        struct cat_desc *desc_ptr = NULL;
                        lockflags = 0;

                        MALLOC(lookup_rsrc, struct cat_lookup_buffer*, sizeof (struct cat_lookup_buffer), M_TEMP, M_WAITOK);
                        if (lookup_rsrc == NULL) {
                                printf("hfs_cnode_teardown: ENOMEM from MALLOC\n");
                                error = ENOMEM;
                                goto out;
                        }
                        else {
                                bzero (lookup_rsrc, sizeof (struct cat_lookup_buffer));
                        }

                        if (cp->c_desc.cd_namelen == 0) {
                                /* Initialize the rsrc descriptor for lookup if necessary*/
                                MAKE_DELETED_NAME (lookup_rsrc->lookup_name, HFS_TEMPLOOKUP_NAMELEN, cp->c_fileid);
                                
                                lookup_rsrc->lookup_desc.cd_nameptr = (const uint8_t*) lookup_rsrc->lookup_name;
                                lookup_rsrc->lookup_desc.cd_namelen = strlen (lookup_rsrc->lookup_name);
                                lookup_rsrc->lookup_desc.cd_parentcnid = hfsmp->hfs_private_desc[FILE_HARDLINKS].cd_cnid;
                                lookup_rsrc->lookup_desc.cd_cnid = cp->c_cnid;  
                                
                                desc_ptr = &lookup_rsrc->lookup_desc;
                        }
                        else {
                                desc_ptr = &cp->c_desc; 
                        }

                        lockflags = hfs_systemfile_lock (hfsmp, SFL_CATALOG, HFS_SHARED_LOCK);

                        error = cat_lookup (hfsmp, desc_ptr, 1, (struct cat_desc *) NULL, 
                                        (struct cat_attr*) NULL, &lookup_rsrc->lookup_fork.ff_data, NULL);

                        hfs_systemfile_unlock (hfsmp, lockflags);
                        
                        if (error) {
                                FREE (lookup_rsrc, M_TEMP);
                                goto out;
                        }

                        /*
                         * Make the filefork in our temporary struct look like a real 
                         * filefork.  Fill in the cp, sysfileinfo and rangelist fields..
                         */
                        rl_init (&lookup_rsrc->lookup_fork.ff_invalidranges);
                        lookup_rsrc->lookup_fork.ff_cp = cp;

                        /* 
                         * If there were no errors, then we have the catalog's fork information 
                         * for the resource fork in question.  Go ahead and delete the data in it now.
                         */

                        error = hfs_release_storage (hfsmp, NULL, &lookup_rsrc->lookup_fork, cp->c_fileid);
                        FREE(lookup_rsrc, M_TEMP);

                        if (error) {
                                goto out;
                        }

                        /*
                         * This fileid's resource fork extents have now been fully deleted on-disk
                         * and this CNID is no longer valid. At this point, we should be able to
                         * zero out cp->c_blocks to indicate there is no data left in this file.
                         */
                        cp->c_blocks = 0;
                }

                /* End the transaction from the start of the file truncation segment */
                if (started_tr) {
                        hfs_end_transaction(hfsmp);
                        started_tr = 0;
                }
        }
        
        /*
         * If we represent the last fork (or none in the case of a dir), 
         * and the cnode has become open-unlinked,
         * AND it has EA's, then we need to get rid of them.
         *
         * Note that this must happen outside of any other transactions
         * because it starts/ends its own transactions and grabs its
         * own locks.  This is to prevent a file with a lot of attributes
         * from creating a transaction that is too large (which panics).
         */
    if ((cp->c_attr.ca_recflags & kHFSHasAttributesMask) != 0 &&
                (cp->c_flag & C_DELETED) && 
                (forkcount <= 1)) {
                
        ea_error = hfs_removeallattr(hfsmp, cp->c_fileid);
    }
        
        
        /*
         * If the cnode represented an open-unlinked file, then now
         * actually remove the cnode's catalog entry and release all blocks
         * it may have been using.  
         */
    if ((cp->c_flag & C_DELETED) && (forkcount <= 1)) {
        /*
         * Mark cnode in transit so that no one can get this 
         * cnode from cnode hash.
         */
                // hfs_chash_mark_in_transit(hfsmp, cp);
                // XXXdbg - remove the cnode from the hash table since it's deleted
                //          otherwise someone could go to sleep on the cnode and not
                //          be woken up until this vnode gets recycled which could be
                //          a very long time...
        hfs_chashremove(hfsmp, cp);
                
        cp->c_flag |= C_NOEXISTS;   // XXXdbg
        cp->c_rdev = 0;
                
        if (started_tr == 0) {
            if (hfs_start_transaction(hfsmp) != 0) {
                                error = EINVAL;
                                goto out;
            }
            started_tr = 1;
        }
                
        /*
         * Reserve some space in the Catalog file.
         */
        if ((error = cat_preflight(hfsmp, CAT_DELETE, &cookie, p))) {
            goto out;
        }
        cat_reserve = 1;
                
        lockflags = hfs_systemfile_lock(hfsmp, SFL_CATALOG | SFL_ATTRIBUTE, HFS_EXCLUSIVE_LOCK);
                
        if (cp->c_blocks > 0) {
            printf("hfs_inactive: deleting non-empty%sfile %d, "
                   "blks %d\n", VNODE_IS_RSRC(vp) ? " rsrc " : " ",
                   (int)cp->c_fileid, (int)cp->c_blocks);
        }
                
                //
        // release the name pointer in the descriptor so that
        // cat_delete() will use the file-id to do the deletion.
        // in the case of hard links this is imperative (in the
        // case of regular files the fileid and cnid are the
        // same so it doesn't matter).
        //
        cat_releasedesc(&cp->c_desc);
                
        /*
         * The descriptor name may be zero,
         * in which case the fileid is used.
         */
        error = cat_delete(hfsmp, &cp->c_desc, &cp->c_attr);
                
        if (error && truncated && (error != ENXIO))
            printf("hfs_inactive: couldn't delete a truncated file!");
                
        /* Update HFS Private Data dir */
        if (error == 0) {
            hfsmp->hfs_private_attr[FILE_HARDLINKS].ca_entries--;
            if (vnode_isdir(vp)) {
                DEC_FOLDERCOUNT(hfsmp, hfsmp->hfs_private_attr[FILE_HARDLINKS]);
            }
            (void)cat_update(hfsmp, &hfsmp->hfs_private_desc[FILE_HARDLINKS],
                                                         &hfsmp->hfs_private_attr[FILE_HARDLINKS], NULL, NULL);
        }
                
        hfs_systemfile_unlock(hfsmp, lockflags);
                
        if (error) {                    
                        goto out;
                }
                
#if QUOTA
        if (hfsmp->hfs_flags & HFS_QUOTAS)
            (void)hfs_chkiq(cp, -1, NOCRED, 0);
#endif /* QUOTA */
                
        /* Already set C_NOEXISTS at the beginning of this block */
        cp->c_flag &= ~C_DELETED;
        cp->c_touch_chgtime = TRUE;
        cp->c_touch_modtime = TRUE;
                
        if (error == 0)
            hfs_volupdate(hfsmp, (v_type == VDIR) ? VOL_RMDIR : VOL_RMFILE, 0);
    }
        
        /*
     * A file may have had delayed allocations, in which case hfs_update
     * would not have updated the catalog record (cat_update).  We need
     * to do that now, before we lose our fork data.  We also need to
     * force the update, or hfs_update will again skip the cat_update.
         *
         * If the file has C_NOEXISTS set, then we can skip the hfs_update call
         * because the catalog entry has already been removed.  There would be no point
     * to looking up the entry in the catalog to modify it when we already know it's gone
         */
    if ((!ISSET(cp->c_flag, C_NOEXISTS)) &&
                ((cp->c_flag & C_MODIFIED) || cp->c_touch_acctime || 
                 cp->c_touch_chgtime || cp->c_touch_modtime)) {
                        
                        if ((cp->c_flag & C_MODIFIED) || cp->c_touch_modtime){
                                cp->c_flag |= C_FORCEUPDATE;
                        }
                        hfs_update(vp, 0);
                }
        
out:
    if (cat_reserve)
        cat_postflight(hfsmp, &cookie, p);
        
    // XXXdbg - have to do this because a goto could have come here
    if (started_tr) {
        hfs_end_transaction(hfsmp);
        started_tr = 0;
    }

#if 0
#if CONFIG_PROTECT
        /* 
         * cnode truncate lock and cnode lock are both held exclusive here. 
         *
         * Go ahead and flush the keys out if this cnode is the last fork
         * and it is not class F.  Class F keys should not be purged because they only
         * exist in memory and have no persistent keys.  Only do this 
         * if we haven't already done it yet (maybe a vnode skipped inactive 
         * and went straight to reclaim).  This function gets called from both reclaim and
         * inactive, so it will happen first in inactive if possible.
         * 
         * We need to be mindful that all pending IO for this file has already been
         * issued and completed before we bzero out the key.  This is because
         * if it isn't, tossing the key here could result in garbage IO being
         * written (by using the bzero'd key) if the writes are happening asynchronously.
         * 
         * In addition, class A files may have already been purged due to the 
         * lock event occurring.
         */
        if (forkcount == 1) {
                struct cprotect *entry = cp->c_cpentry;
                if ((entry) && (entry->cp_pclass != PROTECTION_CLASS_F)) {
                        if ((cp->c_cpentry->cp_flags & CP_KEY_FLUSHED) == 0) {
                                cp->c_cpentry->cp_flags |= CP_KEY_FLUSHED;
                                bzero (cp->c_cpentry->cp_cache_key, cp->c_cpentry->cp_cache_key_len);
                                bzero (cp->c_cpentry->cp_cache_iv_ctx, sizeof(aes_encrypt_ctx));
                        }
                }
        }
#endif
#endif
        
        return error;   
}


/*
 * hfs_vnop_inactive
 *
 * The last usecount on the vnode has gone away, so we need to tear down
 * any remaining data still residing in the cnode.  If necessary, write out
 * remaining blocks or delete the cnode's entry in the catalog.
 */
int
hfs_vnop_inactive(struct vnop_inactive_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct cnode *cp;
        struct hfsmount *hfsmp = VTOHFS(vp);
        struct proc *p = vfs_context_proc(ap->a_context);
        int error = 0;
        int took_trunc_lock = 0;
        enum vtype v_type;
        
        v_type = vnode_vtype(vp);
        cp = VTOC(vp);

        if ((hfsmp->hfs_flags & HFS_READ_ONLY) || vnode_issystem(vp) ||
            (hfsmp->hfs_freezing_proc == p)) {
                error = 0;
                goto inactive_done;
        }       
        
        /*
         * For safety, do NOT call vnode_recycle from inside this function.  This can cause 
         * problems in the following scenario:
         * 
         * vnode_create -> vnode_reclaim_internal -> vclean -> VNOP_INACTIVE
         * 
         * If we're being invoked as a result of a reclaim that was already in-flight, then we
         * cannot call vnode_recycle again.  Being in reclaim means that there are no usecounts or
         * iocounts by definition.  As a result, if we were to call vnode_recycle, it would immediately
         * try to re-enter reclaim again and panic.  
         *
         * Currently, there are three things that can cause us (VNOP_INACTIVE) to get called.
         * 1) last usecount goes away on the vnode (vnode_rele)
         * 2) last iocount goes away on a vnode that previously had usecounts but didn't have 
         *              vnode_recycle called (vnode_put)
         * 3) vclean by way of reclaim
         *
         * In this function we would generally want to call vnode_recycle to speed things 
         * along to ensure that we don't leak blocks due to open-unlinked files.  However, by 
         * virtue of being in this function already, we can call hfs_cnode_teardown, which 
         * will release blocks held by open-unlinked files, and mark them C_NOEXISTS so that 
         * there's no entry in the catalog and no backing store anymore.  If that's the case, 
         * then we really don't care all that much when the vnode actually goes through reclaim.
         * Further, the HFS VNOPs that manipulated the namespace in order to create the open-
         * unlinked file in the first place should have already called vnode_recycle on the vnode
         * to guarantee that it would go through reclaim in a speedy way.
         */
        
        if (cp->c_flag & C_NOEXISTS) {
                /* 
                 * If the cnode has already had its cat entry removed, then 
                 * just skip to the end. We don't need to do anything here.
                 */
                error = 0;
                goto inactive_done;
        }
        
        if ((v_type == VREG || v_type == VLNK)) {
                hfs_lock_truncate(cp, HFS_EXCLUSIVE_LOCK);
                took_trunc_lock = 1;
        }
        
        (void) hfs_lock(cp, HFS_FORCE_LOCK);
        
        /* 
         * Call cnode_teardown to push out dirty blocks to disk, release open-unlinked
         * files' blocks from being in use, and move the cnode from C_DELETED to C_NOEXISTS.
         */
        error = hfs_cnode_teardown (vp, ap->a_context, 0);

    /*
     * Drop the truncate lock before unlocking the cnode
     * (which can potentially perform a vnode_put and
     * recycle the vnode which in turn might require the
     * truncate lock)
     */
        if (took_trunc_lock) {
            hfs_unlock_truncate(cp, 0);
        }
        
        hfs_unlock(cp);
        
inactive_done: 
        
        return error;
}


/*
 * File clean-up (zero fill and shrink peof).
 */

int
hfs_filedone(struct vnode *vp, vfs_context_t context)
{
        struct cnode *cp;
        struct filefork *fp;
        struct hfsmount *hfsmp;
        struct rl_entry *invalid_range;
        off_t leof;
        u_int32_t blks, blocksize;
        /* flags for zero-filling sparse ranges */
        int cluster_flags = IO_CLOSE;
        int cluster_zero_flags = IO_HEADZEROFILL | IO_NOZERODIRTY | IO_NOCACHE;

        cp = VTOC(vp);
        fp = VTOF(vp);
        hfsmp = VTOHFS(vp);
        leof = fp->ff_size;

        if ((hfsmp->hfs_flags & HFS_READ_ONLY) || (fp->ff_blocks == 0))
                return (0);

#if CONFIG_PROTECT
        /* 
         * Figure out if we need to do synchronous IO. 
         * 
         * If the file represents a content-protected file, we may need
         * to issue synchronous IO when we dispatch to the cluster layer.
         * If we didn't, then the IO would go out to the disk asynchronously.
         * If the vnode hits the end of inactive before getting reclaimed, the
         * content protection keys would be wiped/bzeroed out, and we'd end up
         * trying to issue the IO with an invalid key.  This will lead to file 
         * corruption.  IO_SYNC will force the cluster_push to wait until all IOs
         * have completed (though they may be in the track cache).
         */
        if (cp_fs_protected(VTOVFS(vp))) {
                cluster_flags |= IO_SYNC;
                cluster_zero_flags |= IO_SYNC;
        }
#endif

        /* 
         * If we are being invoked from F_SWAPDATAEXTENTS, then we 
         * need to issue synchronous IO; Unless we are sure that all 
         * of the data has been written to the disk, we won't know 
         * that all of the blocks have been allocated properly.
         */
        if (cp->c_flag & C_SWAPINPROGRESS) {
                cluster_flags |= IO_SYNC;
        }

        hfs_unlock(cp);
        (void) cluster_push(vp, cluster_flags);
        hfs_lock(cp, HFS_FORCE_LOCK);

        /*
         * Explicitly zero out the areas of file
         * that are currently marked invalid.
         */
        while ((invalid_range = TAILQ_FIRST(&fp->ff_invalidranges))) {
                off_t start = invalid_range->rl_start;
                off_t end = invalid_range->rl_end;
        
                /* The range about to be written must be validated
                 * first, so that VNOP_BLOCKMAP() will return the
                 * appropriate mapping for the cluster code:
                 */
                rl_remove(start, end, &fp->ff_invalidranges);

                hfs_unlock(cp);
                (void) cluster_write(vp, (struct uio *) 0,
                                     leof, end + 1, start, (off_t)0, cluster_zero_flags);
                hfs_lock(cp, HFS_FORCE_LOCK);
                cp->c_flag |= C_MODIFIED;
        }
        cp->c_flag &= ~C_ZFWANTSYNC;
        cp->c_zftimeout = 0;
        blocksize = VTOVCB(vp)->blockSize;
        blks = leof / blocksize;
        if (((off_t)blks * (off_t)blocksize) != leof)
                blks++;
        /*
         * Shrink the peof to the smallest size neccessary to contain the leof.
         */
        if (blks < fp->ff_blocks) {
                (void) hfs_truncate(vp, leof, IO_NDELAY, 0, 0, context);
        }

        hfs_unlock(cp);
        (void) cluster_push(vp, cluster_flags);
        hfs_lock(cp, HFS_FORCE_LOCK);
        
        /*
         * If the hfs_truncate didn't happen to flush the vnode's
         * information out to disk, force it to be updated now that
         * all invalid ranges have been zero-filled and validated:
         */
        if (cp->c_flag & C_MODIFIED) {
                hfs_update(vp, 0);
        }
        return (0);
}


/*
 * Reclaim a cnode so that it can be used for other purposes.
 */
int
hfs_vnop_reclaim(struct vnop_reclaim_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct cnode *cp;
        struct filefork *fp = NULL;
        struct filefork *altfp = NULL;
        struct hfsmount *hfsmp = VTOHFS(vp);
        vfs_context_t ctx = ap->a_context;
        int reclaim_cnode = 0;
        int err = 0;
        enum vtype v_type;
        
        v_type = vnode_vtype(vp);
        cp = VTOC(vp);
        
        /* 
         * We don't take the truncate lock since by the time reclaim comes along,
         * all dirty pages have been synced and nobody should be competing
         * with us for this thread.
         */
        (void) hfs_lock (cp, HFS_FORCE_LOCK);

        /* 
         * Sync to disk any remaining data in the cnode/vnode.  This includes
         * a call to hfs_update if the cnode has outbound data.
         * 
         * If C_NOEXISTS is set on the cnode, then there's nothing teardown needs to do
         * because the catalog entry for this cnode is already gone.
         */
        if (!ISSET(cp->c_flag, C_NOEXISTS)) {
                err = hfs_cnode_teardown(vp, ctx, 1);
        }

        /*
         * Keep track of an inactive hot file.
         */
        if (!vnode_isdir(vp) &&
            !vnode_issystem(vp) &&
            !(cp->c_flag & (C_DELETED | C_NOEXISTS)) ) {
                (void) hfs_addhotfile(vp);
        }
        vnode_removefsref(vp);

        /*
         * Find file fork for this vnode (if any)
         * Also check if another fork is active
         */
        if (cp->c_vp == vp) {
                fp = cp->c_datafork;
                altfp = cp->c_rsrcfork;

                cp->c_datafork = NULL;
                cp->c_vp = NULL;
        } else if (cp->c_rsrc_vp == vp) {
                fp = cp->c_rsrcfork;
                altfp = cp->c_datafork;

                cp->c_rsrcfork = NULL;
                cp->c_rsrc_vp = NULL;
        } else {
                panic("hfs_vnop_reclaim: vp points to wrong cnode (vp=%p cp->c_vp=%p cp->c_rsrc_vp=%p)\n", vp, cp->c_vp, cp->c_rsrc_vp);
        }
        /*
         * On the last fork, remove the cnode from its hash chain.
         */
        if (altfp == NULL) {
                /* If we can't remove it then the cnode must persist! */
                if (hfs_chashremove(hfsmp, cp) == 0)
                        reclaim_cnode = 1;
                /* 
                 * Remove any directory hints
                 */
                if (vnode_isdir(vp)) {
                        hfs_reldirhints(cp, 0);
                }
                
                if(cp->c_flag & C_HARDLINK) {
                        hfs_relorigins(cp);
                }
        }
        /* Release the file fork and related data */
        if (fp) {
                /* Dump cached symlink data */
                if (vnode_islnk(vp) && (fp->ff_symlinkptr != NULL)) {
                        FREE(fp->ff_symlinkptr, M_TEMP);
                }               
                FREE_ZONE(fp, sizeof(struct filefork), M_HFSFORK);
        }

        /* 
         * If there was only one active fork then we can release the cnode.
         */
        if (reclaim_cnode) {
                hfs_chashwakeup(hfsmp, cp, H_ALLOC | H_TRANSIT);
                hfs_reclaim_cnode(cp);
        } 
        else  {
                /* 
                 * cnode in use.  If it is a directory, it could have 
                 * no live forks. Just release the lock.
                 */
                hfs_unlock(cp);
        }

        vnode_clearfsnode(vp);
        return (0);
}


extern int (**hfs_vnodeop_p) (void *);
extern int (**hfs_std_vnodeop_p) (void *);
extern int (**hfs_specop_p)  (void *);
#if FIFO
extern int (**hfs_fifoop_p)  (void *);
#endif

/*
 * hfs_getnewvnode - get new default vnode
 *
 * The vnode is returned with an iocount and the cnode locked
 */
int
hfs_getnewvnode(
        struct hfsmount *hfsmp,
        struct vnode *dvp,
        struct componentname *cnp,
        struct cat_desc *descp,
        int flags,
        struct cat_attr *attrp,
        struct cat_fork *forkp,
        struct vnode **vpp,
        int *out_flags)
{
        struct mount *mp = HFSTOVFS(hfsmp);
        struct vnode *vp = NULL;
        struct vnode **cvpp;
        struct vnode *tvp = NULLVP;
        struct cnode *cp = NULL;
        struct filefork *fp = NULL;
        int hfs_standard = 0;
        int retval;
        int issystemfile;
        int wantrsrc;
        int hflags = 0;
        struct vnode_fsparam vfsp;
        enum vtype vtype;
#if QUOTA
        int i;
#endif /* QUOTA */
        
        hfs_standard = (hfsmp->hfs_flags & HFS_STANDARD);

        if (attrp->ca_fileid == 0) {
                *vpp = NULL;
                return (ENOENT);
        }

#if !FIFO
        if (IFTOVT(attrp->ca_mode) == VFIFO) {
                *vpp = NULL;
                return (ENOTSUP);
        }
#endif /* !FIFO */
        vtype = IFTOVT(attrp->ca_mode);
        issystemfile = (descp->cd_flags & CD_ISMETA) && (vtype == VREG);
        wantrsrc = flags & GNV_WANTRSRC;

        /* Zero out the out_flags */
        *out_flags = 0;

#ifdef HFS_CHECK_LOCK_ORDER
        /*
         * The only case were its permissible to hold the parent cnode
         * lock is during a create operation (hfs_makenode) or when
         * we don't need the cnode lock (GNV_SKIPLOCK).
         */
        if ((dvp != NULL) &&
            (flags & (GNV_CREATE | GNV_SKIPLOCK)) == 0 &&
            VTOC(dvp)->c_lockowner == current_thread()) {
                panic("hfs_getnewvnode: unexpected hold of parent cnode %p", VTOC(dvp));
        }
#endif /* HFS_CHECK_LOCK_ORDER */

        /*
         * Get a cnode (new or existing)
         */
        cp = hfs_chash_getcnode(hfsmp, attrp->ca_fileid, vpp, wantrsrc, 
                                                        (flags & GNV_SKIPLOCK), out_flags, &hflags);

        /*
         * If the id is no longer valid for lookups we'll get back a NULL cp.
         */
        if (cp == NULL) {
                return (ENOENT);
        }

        /* 
         * If we get a cnode/vnode pair out of hfs_chash_getcnode, then update the 
         * descriptor in the cnode as needed if the cnode represents a hardlink.  
         * We want the caller to get the most up-to-date copy of the descriptor
         * as possible. However, we only do anything here if there was a valid vnode.
         * If there isn't a vnode, then the cnode is brand new and needs to be initialized
         * as it doesn't have a descriptor or cat_attr yet.
         * 
         * If we are about to replace the descriptor with the user-supplied one, then validate
         * that the descriptor correctly acknowledges this item is a hardlink.  We could be
         * subject to a race where the calling thread invoked cat_lookup, got a valid lookup 
         * result but the file was not yet a hardlink. With sufficient delay between there
         * and here, we might accidentally copy in the raw inode ID into the descriptor in the
         * call below.  If the descriptor's CNID is the same as the fileID then it must
         * not yet have been a hardlink when the lookup occurred.
         */
        
        if (!(hfs_checkdeleted(cp))) {
                if ((cp->c_flag & C_HARDLINK) && descp->cd_nameptr && descp->cd_namelen > 0) {
                        /* If cnode is uninitialized, its c_attr will be zeroed out; cnids wont match. */
                        if ((descp->cd_cnid == cp->c_attr.ca_fileid)  &&
                                        (attrp->ca_linkcount != cp->c_attr.ca_linkcount)){
                                if ((flags & GNV_SKIPLOCK) == 0) {
                                        /* 
                                         * Then we took the lock. Drop it before calling
                                         * vnode_put, which may invoke hfs_vnop_inactive and need to take 
                                         * the cnode lock again.
                                         */
                                        hfs_unlock(cp);
                                }
                                
                                /* 
                                 * Emit ERECYCLE and GNV_CAT_ATTRCHANGED to 
                                 * force a re-drive in the lookup routine.  
                                 * Drop the iocount on the vnode obtained from 
                                 * chash_getcnode if needed.
                                 */     
                                if (*vpp != NULL) {
                                        vnode_put (*vpp);
                                        *vpp = NULL;
                                }
                                
                                /*
                                 * If we raced with VNOP_RECLAIM for this vnode, the hash code could
                                 * have observed it after the c_vp or c_rsrc_vp fields had been torn down;
                                 * the hash code peeks at those fields without holding the cnode lock because
                                 * it needs to be fast.  As a result, we may have set H_ATTACH in the chash
                                 * call above.  Since we're bailing out, unset whatever flags we just set, and
                                 * wake up all waiters for this cnode.
                                 */
                                if (hflags) {
                                        hfs_chashwakeup(hfsmp, cp, hflags);
                                }
                                
                                *out_flags = GNV_CAT_ATTRCHANGED;
                                return ERECYCLE;        
                        }
                        else {
                                /* 
                                 * Otherwise, CNID != fileid. Go ahead and copy in the new descriptor. 
                                 *
                                 * Replacing the descriptor here is fine because we looked up the item without
                                 * a vnode in hand before.  If a vnode existed, its identity must be attached to this
                                 * item.  We are not susceptible to the lookup fastpath issue at this point.
                                 */
                                replace_desc(cp, descp);
                        }
                }
        }
        
        /* Check if we found a matching vnode */
        if (*vpp != NULL) {
                return (0);
        }

        /*
         * If this is a new cnode then initialize it.
         */
        if (ISSET(cp->c_hflag, H_ALLOC)) {
                lck_rw_init(&cp->c_truncatelock, hfs_rwlock_group, hfs_lock_attr);
#if HFS_COMPRESSION
                cp->c_decmp = NULL;
#endif

                /* Make sure its still valid (ie exists on disk). */
                if (!(flags & GNV_CREATE)) {
                        int error = 0;
                        if (!hfs_valid_cnode (hfsmp, dvp, (wantrsrc ? NULL : cnp), cp->c_fileid, attrp, &error)) {
                                hfs_chash_abort(hfsmp, cp);
                                hfs_reclaim_cnode(cp);
                                *vpp = NULL;
                                /* 
                                 * If we hit this case, that means that the entry was there in the catalog when
                                 * we did a cat_lookup earlier.  Think hfs_lookup.  However, in between the time
                                 * that we checked the catalog and the time we went to get a vnode/cnode for it,
                                 * it had been removed from the namespace and the vnode totally reclaimed.  As a result,
                                 * it's not there in the catalog during the check in hfs_valid_cnode and we bubble out
                                 * an ENOENT.  To indicate to the caller that they should really double-check the
                                 * entry (it could have been renamed over and gotten a new fileid), we mark a bit
                                 * in the output flags.
                                 */
                                if (error == ENOENT) {
                                        *out_flags = GNV_CAT_DELETED;
                                        return ENOENT;  
                                }

                                /*
                                 * Also, we need to protect the cat_attr acquired during hfs_lookup and passed into
                                 * this function as an argument because the catalog may have changed w.r.t hardlink
                                 * link counts and the firstlink field.  If that validation check fails, then let 
                                 * lookup re-drive itself to get valid/consistent data with the same failure condition below.
                                 */
                                if (error == ERECYCLE) {
                                        *out_flags = GNV_CAT_ATTRCHANGED;
                                        return (ERECYCLE);
                                }
                        }
                }
                bcopy(attrp, &cp->c_attr, sizeof(struct cat_attr));
                bcopy(descp, &cp->c_desc, sizeof(struct cat_desc));

                /* The name was inherited so clear descriptor state... */
                descp->cd_namelen = 0;
                descp->cd_nameptr = NULL;
                descp->cd_flags &= ~CD_HASBUF;

                /* Tag hardlinks */
                if ((vtype == VREG || vtype == VDIR) &&
                    ((descp->cd_cnid != attrp->ca_fileid) ||
                     (attrp->ca_recflags & kHFSHasLinkChainMask))) {
                        cp->c_flag |= C_HARDLINK;
                }
                /*
                 * Fix-up dir link counts.
                 *
                 * Earlier versions of Leopard used ca_linkcount for posix
                 * nlink support (effectively the sub-directory count + 2).
                 * That is now accomplished using the ca_dircount field with
                 * the corresponding kHFSHasFolderCountMask flag.
                 *
                 * For directories the ca_linkcount is the true link count,
                 * tracking the number of actual hardlinks to a directory.
                 *
                 * We only do this if the mount has HFS_FOLDERCOUNT set;
                 * at the moment, we only set that for HFSX volumes.
                 */
                if ((hfsmp->hfs_flags & HFS_FOLDERCOUNT) && 
                    (vtype == VDIR) &&
                    !(attrp->ca_recflags & kHFSHasFolderCountMask) &&
                    (cp->c_attr.ca_linkcount > 1)) {
                        if (cp->c_attr.ca_entries == 0)
                                cp->c_attr.ca_dircount = 0;
                        else
                                cp->c_attr.ca_dircount = cp->c_attr.ca_linkcount - 2;

                        cp->c_attr.ca_linkcount = 1;
                        cp->c_attr.ca_recflags |= kHFSHasFolderCountMask;
                        if ( !(hfsmp->hfs_flags & HFS_READ_ONLY) )
                                cp->c_flag |= C_MODIFIED;
                }
#if QUOTA
                if (hfsmp->hfs_flags & HFS_QUOTAS) {
                        for (i = 0; i < MAXQUOTAS; i++)
                                cp->c_dquot[i] = NODQUOT;
                }
#endif /* QUOTA */
                /* Mark the output flag that we're vending a new cnode */
                *out_flags |= GNV_NEW_CNODE;
        }

        if (vtype == VDIR) {
                if (cp->c_vp != NULL)
                        panic("hfs_getnewvnode: orphaned vnode (data)");
                cvpp = &cp->c_vp;
        } else {
                if (forkp && attrp->ca_blocks < forkp->cf_blocks)
                        panic("hfs_getnewvnode: bad ca_blocks (too small)");
                /*
                 * Allocate and initialize a file fork...
                 */
                MALLOC_ZONE(fp, struct filefork *, sizeof(struct filefork),
                        M_HFSFORK, M_WAITOK);
                fp->ff_cp = cp;
                if (forkp)
                        bcopy(forkp, &fp->ff_data, sizeof(struct cat_fork));
                else
                        bzero(&fp->ff_data, sizeof(struct cat_fork));
                rl_init(&fp->ff_invalidranges);
                fp->ff_sysfileinfo = 0;

                if (wantrsrc) {
                        if (cp->c_rsrcfork != NULL)
                                panic("hfs_getnewvnode: orphaned rsrc fork");
                        if (cp->c_rsrc_vp != NULL)
                                panic("hfs_getnewvnode: orphaned vnode (rsrc)");
                        cp->c_rsrcfork = fp;
                        cvpp = &cp->c_rsrc_vp;
                        if ( (tvp = cp->c_vp) != NULLVP )
                                cp->c_flag |= C_NEED_DVNODE_PUT;
                } else {
                        if (cp->c_datafork != NULL)
                                panic("hfs_getnewvnode: orphaned data fork");
                        if (cp->c_vp != NULL)
                                panic("hfs_getnewvnode: orphaned vnode (data)");
                        cp->c_datafork = fp;
                        cvpp = &cp->c_vp;
                        if ( (tvp = cp->c_rsrc_vp) != NULLVP)
                                cp->c_flag |= C_NEED_RVNODE_PUT;
                }
        }
        if (tvp != NULLVP) {
                /*
                 * grab an iocount on the vnode we weren't
                 * interested in (i.e. we want the resource fork
                 * but the cnode already has the data fork)
                 * to prevent it from being
                 * recycled by us when we call vnode_create
                 * which will result in a deadlock when we
                 * try to take the cnode lock in hfs_vnop_fsync or
                 * hfs_vnop_reclaim... vnode_get can be called here
                 * because we already hold the cnode lock which will
                 * prevent the vnode from changing identity until
                 * we drop it.. vnode_get will not block waiting for
                 * a change of state... however, it will return an
                 * error if the current iocount == 0 and we've already
                 * started to terminate the vnode... we don't need/want to
                 * grab an iocount in the case since we can't cause
                 * the fileystem to be re-entered on this thread for this vp
                 *
                 * the matching vnode_put will happen in hfs_unlock
                 * after we've dropped the cnode lock
                 */
                if ( vnode_get(tvp) != 0)
                        cp->c_flag &= ~(C_NEED_RVNODE_PUT | C_NEED_DVNODE_PUT);
        }
        vfsp.vnfs_mp = mp;
        vfsp.vnfs_vtype = vtype;
        vfsp.vnfs_str = "hfs";
        if ((cp->c_flag & C_HARDLINK) && (vtype == VDIR)) {
                vfsp.vnfs_dvp = NULL;  /* no parent for me! */
                vfsp.vnfs_cnp = NULL;  /* no name for me! */
        } else {
                vfsp.vnfs_dvp = dvp;
                vfsp.vnfs_cnp = cnp;
        }
        vfsp.vnfs_fsnode = cp;

        /*
         * Special Case HFS Standard VNOPs from HFS+, since
         * HFS standard is readonly/deprecated as of 10.6 
         */

#if FIFO
        if (vtype == VFIFO ) 
                vfsp.vnfs_vops = hfs_fifoop_p;
        else
#endif
        if (vtype == VBLK || vtype == VCHR)
                vfsp.vnfs_vops = hfs_specop_p;
        else if (hfs_standard)
                vfsp.vnfs_vops = hfs_std_vnodeop_p;
        else 
                vfsp.vnfs_vops = hfs_vnodeop_p;

        if (vtype == VBLK || vtype == VCHR)
                vfsp.vnfs_rdev = attrp->ca_rdev;
        else
                vfsp.vnfs_rdev = 0;

        if (forkp) 
                vfsp.vnfs_filesize = forkp->cf_size;
        else
                vfsp.vnfs_filesize = 0;

        vfsp.vnfs_flags = VNFS_ADDFSREF;
        if (dvp == NULLVP || cnp == NULL || !(cnp->cn_flags & MAKEENTRY) || (flags & GNV_NOCACHE))
                vfsp.vnfs_flags |= VNFS_NOCACHE;

        /* Tag system files */
        vfsp.vnfs_marksystem = issystemfile;

        /* Tag root directory */
        if (descp->cd_cnid == kHFSRootFolderID)
                vfsp.vnfs_markroot = 1;
        else    
                vfsp.vnfs_markroot = 0;

        if ((retval = vnode_create(VNCREATE_FLAVOR, VCREATESIZE, &vfsp, cvpp))) {
                if (fp) {
                        if (fp == cp->c_datafork)
                                cp->c_datafork = NULL;
                        else
                                cp->c_rsrcfork = NULL;

                        FREE_ZONE(fp, sizeof(struct filefork), M_HFSFORK);
                }
                /*
                 * If this is a newly created cnode or a vnode reclaim
                 * occurred during the attachment, then cleanup the cnode.
                 */
                if ((cp->c_vp == NULL) && (cp->c_rsrc_vp == NULL)) {
                        hfs_chash_abort(hfsmp, cp);
                        hfs_reclaim_cnode(cp);
                } 
                else {
                        hfs_chashwakeup(hfsmp, cp, H_ALLOC | H_ATTACH);
                        if ((flags & GNV_SKIPLOCK) == 0){
                                hfs_unlock(cp);
                        }
                }
                *vpp = NULL;
                return (retval);
        }
        vp = *cvpp;
        vnode_settag(vp, VT_HFS);
        if (cp->c_flag & C_HARDLINK) {
                vnode_setmultipath(vp);
        }
        /*
         * Tag resource fork vnodes as needing an VNOP_INACTIVE
         * so that any deferred removes (open unlinked files)
         * have the chance to process the resource fork.
         */
        if (VNODE_IS_RSRC(vp)) {
                int err;
                KERNEL_DEBUG_CONSTANT((FSDBG_CODE(DBG_FSRW, 37)), cp->c_vp, cp->c_rsrc_vp, 0, 0, 0);

                /* Force VL_NEEDINACTIVE on this vnode */
                err = vnode_ref(vp);
                if (err == 0) {
                        vnode_rele(vp);
                }
        }
        hfs_chashwakeup(hfsmp, cp, H_ALLOC | H_ATTACH);

        /*
         * Stop tracking an active hot file.
         */
        if (!(flags & GNV_CREATE) && (vtype != VDIR) && !issystemfile) {
                (void) hfs_removehotfile(vp);
        }
        
#if CONFIG_PROTECT
        /* Initialize the cp data structures. The key should be in place now. */
        if (!issystemfile && (*out_flags & GNV_NEW_CNODE)) {
                cp_entry_init(cp, mp);
        }
#endif

        *vpp = vp;
        return (0);
}


static void
hfs_reclaim_cnode(struct cnode *cp)
{
#if QUOTA
        int i;

        for (i = 0; i < MAXQUOTAS; i++) {
                if (cp->c_dquot[i] != NODQUOT) {
                        dqreclaim(cp->c_dquot[i]);
                        cp->c_dquot[i] = NODQUOT;
                }
        }
#endif /* QUOTA */

        /* 
         * If the descriptor has a name then release it
         */
        if ((cp->c_desc.cd_flags & CD_HASBUF) && (cp->c_desc.cd_nameptr != 0)) {
                const char *nameptr;

                nameptr = (const char *) cp->c_desc.cd_nameptr;
                cp->c_desc.cd_nameptr = 0;
                cp->c_desc.cd_flags &= ~CD_HASBUF;
                cp->c_desc.cd_namelen = 0;
                vfs_removename(nameptr);
        }
        
        /*
         * We only call this function if we are in hfs_vnop_reclaim and 
         * attempting to reclaim a cnode with only one live fork.  Because the vnode
         * went through reclaim, any future attempts to use this item will have to
         * go through lookup again, which will need to create a new vnode.  Thus,
         * destroying the locks below (while they were still held during our parent 
         * function hfs_vnop_reclaim) is safe.
         */     
        
        lck_rw_destroy(&cp->c_rwlock, hfs_rwlock_group);
        lck_rw_destroy(&cp->c_truncatelock, hfs_rwlock_group);
#if HFS_COMPRESSION
        if (cp->c_decmp) {
                decmpfs_cnode_destroy(cp->c_decmp);
                FREE_ZONE(cp->c_decmp, sizeof(*(cp->c_decmp)), M_DECMPFS_CNODE);
        }
#endif
#if CONFIG_PROTECT
        cp_entry_destroy(&cp->c_cpentry);
#endif
        
        
        bzero(cp, sizeof(struct cnode));
        FREE_ZONE(cp, sizeof(struct cnode), M_HFSNODE);
}


/*
 * hfs_valid_cnode
 *
 * This function is used to validate data that is stored in-core against what is contained
 * in the catalog.  Common uses include validating that the parent-child relationship still exist
 * for a specific directory entry (guaranteeing it has not been renamed into a different spot) at
 * the point of the check.
 */
int
hfs_valid_cnode(struct hfsmount *hfsmp, struct vnode *dvp, struct componentname *cnp, 
                cnid_t cnid, struct cat_attr *cattr, int *error)
{
        struct cat_attr attr;
        struct cat_desc cndesc;
        int stillvalid = 0;
        int lockflags;

        /* System files are always valid */
        if (cnid < kHFSFirstUserCatalogNodeID) {
                *error = 0;
                return (1);
        }

        /* XXX optimization:  check write count in dvp */

        lockflags = hfs_systemfile_lock(hfsmp, SFL_CATALOG, HFS_SHARED_LOCK);

        if (dvp && cnp) {
                int lookup = 0;
                struct cat_fork fork;
                bzero(&cndesc, sizeof(cndesc));
                cndesc.cd_nameptr = (const u_int8_t *)cnp->cn_nameptr;
                cndesc.cd_namelen = cnp->cn_namelen;
                cndesc.cd_parentcnid = VTOC(dvp)->c_fileid;
                cndesc.cd_hint = VTOC(dvp)->c_childhint;

                /* 
                 * We have to be careful when calling cat_lookup.  The result argument
                 * 'attr' may get different results based on whether or not you ask
                 * for the filefork to be supplied as output.  This is because cat_lookupbykey
                 * will attempt to do basic validation/smoke tests against the resident
                 * extents if there are no overflow extent records, but it needs someplace
                 * in memory to store the on-disk fork structures.
                 *
                 * Since hfs_lookup calls cat_lookup with a filefork argument, we should
                 * do the same here, to verify that block count differences are not
                 * due to calling the function with different styles.  cat_lookupbykey
                 * will request the volume be fsck'd if there is true on-disk corruption
                 * where the number of blocks does not match the number generated by 
                 * summing the number of blocks in the resident extents.
                 */
                
                lookup = cat_lookup (hfsmp, &cndesc, 0, NULL, &attr, &fork, NULL);

                if ((lookup == 0) && (cnid == attr.ca_fileid)) {
                        stillvalid = 1;
                        *error = 0;
                }
                else {
                        *error = ENOENT;
                }
        
                /*
                 * In hfs_getnewvnode, we may encounter a time-of-check vs. time-of-vnode creation 
                 * race.  Specifically, if there is no vnode/cnode pair for the directory entry 
                 * being looked up, we have to go to the catalog.  But since we don't hold any locks (aside
                 * from the dvp in 'shared' mode) there is nothing to protect us against the catalog record
                 * changing in between the time we do the cat_lookup there and the time we re-grab the 
                 * catalog lock above to do another cat_lookup. 
                 * 
                 * However, we need to check more than just the CNID and parent-child name relationships above.  
                 * Hardlinks can suffer the same race in the following scenario:  Suppose we do a 
                 * cat_lookup, and find a leaf record and a raw inode for a hardlink.  Now, we have 
                 * the cat_attr in hand (passed in above).  But in between then and now, the vnode was 
                 * created by a competing hfs_getnewvnode call, and is manipulated and reclaimed before we get 
                 * a chance to do anything.  This is possible if there are a lot of threads thrashing around
                 * with the cnode hash.  In this case, if we don't check/validate the cat_attr in-hand, we will
                 * blindly stuff it into the cnode, which will make the in-core data inconsistent with what is 
                 * on disk.  So validate the cat_attr below, if required.  This race cannot happen if the cnode/vnode
                 * already exists, as it does in the case of rename and delete. 
                 */ 
                if (stillvalid && cattr != NULL) {
                        if (cattr->ca_linkcount != attr.ca_linkcount) {
                                stillvalid = 0;
                                *error = ERECYCLE;
                                goto notvalid;
                        }
                        
                        if (cattr->ca_union1.cau_linkref != attr.ca_union1.cau_linkref) {
                                stillvalid = 0;
                                *error = ERECYCLE;
                                goto notvalid;
                        }

                        if (cattr->ca_union3.cau_firstlink != attr.ca_union3.cau_firstlink) {
                                stillvalid = 0;
                                *error = ERECYCLE;
                                goto notvalid;
                        }

                        if (cattr->ca_union2.cau_blocks != attr.ca_union2.cau_blocks) {
                                stillvalid = 0;
                                *error = ERECYCLE;
                                goto notvalid;
                        }
                }
        } else {
                if (cat_idlookup(hfsmp, cnid, 0, NULL, NULL, NULL) == 0) {
                        stillvalid = 1;
                        *error = 0;
                }
                else {
                        *error = ENOENT;
                }
        }
notvalid:
        hfs_systemfile_unlock(hfsmp, lockflags);

        return (stillvalid);
}


/*
 * Per HI and Finder requirements, HFS should add in the
 * date/time that a particular directory entry was added 
 * to the containing directory. 
 * This is stored in the extended Finder Info for the 
 * item in question.
 *
 * Note that this field is also set explicitly in the hfs_vnop_setxattr code.
 * We must ignore user attempts to set this part of the finderinfo, and
 * so we need to save a local copy of the date added, write in the user 
 * finderinfo, then stuff the value back in.  
 */
void hfs_write_dateadded (struct cat_attr *attrp, u_int32_t dateadded) {
        u_int8_t *finfo = NULL;

        /* overlay the FinderInfo to the correct pointer, and advance */
        finfo = (u_int8_t*)attrp->ca_finderinfo;
        finfo = finfo + 16;

        /* 
         * Make sure to write it out as big endian, since that's how
         * finder info is defined.  
         * 
         * NOTE: This is a Unix-epoch timestamp, not a HFS/Traditional Mac timestamp.
         */
        if (S_ISREG(attrp->ca_mode)) {
                struct FndrExtendedFileInfo *extinfo = (struct FndrExtendedFileInfo *)finfo;
                extinfo->date_added = OSSwapHostToBigInt32(dateadded);
                attrp->ca_recflags |= kHFSHasDateAddedMask; 
        }
        else if (S_ISDIR(attrp->ca_mode)) {
                struct FndrExtendedDirInfo *extinfo = (struct FndrExtendedDirInfo *)finfo;
                extinfo->date_added = OSSwapHostToBigInt32(dateadded);          
                                attrp->ca_recflags |= kHFSHasDateAddedMask; 
        }
        /* If it were neither directory/file, then we'd bail out */
        return;
}


u_int32_t hfs_get_dateadded (struct cnode *cp) {
        u_int8_t *finfo = NULL;
        u_int32_t dateadded = 0;

        if ((cp->c_attr.ca_recflags & kHFSHasDateAddedMask) == 0) {
                /* Date added was never set.  Return 0. */
                return dateadded;
        }


        /* overlay the FinderInfo to the correct pointer, and advance */
        finfo = (u_int8_t*)cp->c_finderinfo;
        finfo = finfo + 16;

        /* 
         * FinderInfo is written out in big endian... make sure to convert it to host
         * native before we use it.
         */
        if (S_ISREG(cp->c_attr.ca_mode)) {
                struct FndrExtendedFileInfo *extinfo = (struct FndrExtendedFileInfo *)finfo;
                dateadded = OSSwapBigToHostInt32 (extinfo->date_added);
        }
        else if (S_ISDIR(cp->c_attr.ca_mode)) {
                struct FndrExtendedDirInfo *extinfo = (struct FndrExtendedDirInfo *)finfo;
                dateadded = OSSwapBigToHostInt32 (extinfo->date_added);
        }

        return dateadded;
}

/*
 * Touch cnode times based on c_touch_xxx flags
 *
 * cnode must be locked exclusive
 *
 * This will also update the volume modify time
 */
void
hfs_touchtimes(struct hfsmount *hfsmp, struct cnode* cp)
{
        vfs_context_t ctx;
        /* don't modify times if volume is read-only */
        if (hfsmp->hfs_flags & HFS_READ_ONLY) {
                cp->c_touch_acctime = FALSE;
                cp->c_touch_chgtime = FALSE;
                cp->c_touch_modtime = FALSE;
                return;
        }
        else if (hfsmp->hfs_flags & HFS_STANDARD) {
        /* HFS Standard doesn't support access times */
                cp->c_touch_acctime = FALSE;
        }

        ctx = vfs_context_current();
        /*
         * Skip access time updates if:
         *      . MNT_NOATIME is set
         *      . a file system freeze is in progress
         *      . a file system resize is in progress
         *      . the vnode associated with this cnode is marked for rapid aging
         */
        if (cp->c_touch_acctime) {
                if ((vfs_flags(hfsmp->hfs_mp) & MNT_NOATIME) ||
                    (hfsmp->hfs_freezing_proc != NULL) ||
                    (hfsmp->hfs_flags & HFS_RESIZE_IN_PROGRESS) ||
                    (cp->c_vp && ((vnode_israge(cp->c_vp) || (vfs_ctx_skipatime(ctx)))))) {
                                
                        cp->c_touch_acctime = FALSE;
                }
        }
        if (cp->c_touch_acctime || cp->c_touch_chgtime || 
                cp->c_touch_modtime || (cp->c_flag & C_NEEDS_DATEADDED)) {
                struct timeval tv;
                int touchvol = 0;

                microtime(&tv);
                    
                if (cp->c_touch_acctime) {
                        cp->c_atime = tv.tv_sec;
                        /*
                         * When the access time is the only thing changing
                         * then make sure its sufficiently newer before
                         * committing it to disk.
                         */
                        if ((((u_int32_t)cp->c_atime - (u_int32_t)(cp)->c_attr.ca_atimeondisk) >
                              ATIME_ONDISK_ACCURACY)) {
                                cp->c_flag |= C_MODIFIED;
                        }
                        cp->c_touch_acctime = FALSE;
                }
                if (cp->c_touch_modtime) {
                        cp->c_mtime = tv.tv_sec;
                        cp->c_touch_modtime = FALSE;
                        cp->c_flag |= C_MODIFIED;
                        touchvol = 1;
#if 1
                        /*
                         * HFS dates that WE set must be adjusted for DST
                         */
                        if ((hfsmp->hfs_flags & HFS_STANDARD) && gTimeZone.tz_dsttime) {
                                cp->c_mtime += 3600;
                        }
#endif
                }
                if (cp->c_touch_chgtime) {
                        cp->c_ctime = tv.tv_sec;
                        cp->c_touch_chgtime = FALSE;
                        cp->c_flag |= C_MODIFIED;
                        touchvol = 1;
                }

                if (cp->c_flag & C_NEEDS_DATEADDED) {
                        hfs_write_dateadded (&(cp->c_attr), tv.tv_sec);
                        cp->c_flag |= C_MODIFIED;
                        /* untwiddle the bit */
                        cp->c_flag &= ~C_NEEDS_DATEADDED;
                        touchvol = 1;
                }

                /* Touch the volume modtime if needed */
                if (touchvol) {
                        MarkVCBDirty(hfsmp);
                        HFSTOVCB(hfsmp)->vcbLsMod = tv.tv_sec;
                }
        }
}

/*
 * Lock a cnode.
 */
int
hfs_lock(struct cnode *cp, enum hfslocktype locktype)
{
        void * thread = current_thread();

        if (cp->c_lockowner == thread) {
                /*
                 * Only the extents and bitmap file's support lock recursion.
                 */
                if ((cp->c_fileid == kHFSExtentsFileID) ||
                    (cp->c_fileid == kHFSAllocationFileID)) {
                        cp->c_syslockcount++;
                } else {
                        panic("hfs_lock: locking against myself!");
                }
        } else if (locktype == HFS_SHARED_LOCK) {
                lck_rw_lock_shared(&cp->c_rwlock);
                cp->c_lockowner = HFS_SHARED_OWNER;

        } else /* HFS_EXCLUSIVE_LOCK */ {
                lck_rw_lock_exclusive(&cp->c_rwlock);
                cp->c_lockowner = thread;

                /*
                 * Only the extents and bitmap file's support lock recursion.
                 */
                if ((cp->c_fileid == kHFSExtentsFileID) ||
                    (cp->c_fileid == kHFSAllocationFileID)) {
                        cp->c_syslockcount = 1;
                }
        }

#ifdef HFS_CHECK_LOCK_ORDER
        /*
         * Regular cnodes (non-system files) cannot be locked
         * while holding the journal lock or a system file lock.
         */
        if (!(cp->c_desc.cd_flags & CD_ISMETA) &&
            ((cp->c_fileid > kHFSFirstUserCatalogNodeID) || (cp->c_fileid == kHFSRootFolderID))) {
                vnode_t vp = NULLVP;

                /* Find corresponding vnode. */
                if (cp->c_vp != NULLVP && VTOC(cp->c_vp) == cp) {
                        vp = cp->c_vp;
                } else if (cp->c_rsrc_vp != NULLVP && VTOC(cp->c_rsrc_vp) == cp) {
                        vp = cp->c_rsrc_vp;
                }
                if (vp != NULLVP) {
                        struct hfsmount *hfsmp = VTOHFS(vp);

                        if (hfsmp->jnl && (journal_owner(hfsmp->jnl) == thread)) {
                                /* This will eventually be a panic here. */
                                printf("hfs_lock: bad lock order (cnode after journal)\n");
                        }
                        if (hfsmp->hfs_catalog_cp && hfsmp->hfs_catalog_cp->c_lockowner == thread) {
                                panic("hfs_lock: bad lock order (cnode after catalog)");
                        }
                        if (hfsmp->hfs_attribute_cp && hfsmp->hfs_attribute_cp->c_lockowner == thread) {
                                panic("hfs_lock: bad lock order (cnode after attribute)");
                        }
                        if (hfsmp->hfs_extents_cp && hfsmp->hfs_extents_cp->c_lockowner == thread) {
                                panic("hfs_lock: bad lock order (cnode after extents)");
                        }
                }
        }
#endif /* HFS_CHECK_LOCK_ORDER */
        
        /*
         * Skip cnodes that no longer exist (were deleted).
         */
        if ((locktype != HFS_FORCE_LOCK) &&
            ((cp->c_desc.cd_flags & CD_ISMETA) == 0) &&
            (cp->c_flag & C_NOEXISTS)) {
                hfs_unlock(cp);
                return (ENOENT);
        }
        return (0);
}

/*
 * Lock a pair of cnodes.
 */
int
hfs_lockpair(struct cnode *cp1, struct cnode *cp2, enum hfslocktype locktype)
{
        struct cnode *first, *last;
        int error;

        /*
         * If cnodes match then just lock one.
         */
        if (cp1 == cp2) {
                return hfs_lock(cp1, locktype);
        }

        /*
         * Lock in cnode address order.
         */
        if (cp1 < cp2) {
                first = cp1;
                last = cp2;
        } else {
                first = cp2;
                last = cp1;
        }

        if ( (error = hfs_lock(first, locktype))) {
                return (error);
        }
        if ( (error = hfs_lock(last, locktype))) {
                hfs_unlock(first);
                return (error);
        }
        return (0);
}

/*
 * Check ordering of two cnodes. Return true if they are are in-order.
 */
static int
hfs_isordered(struct cnode *cp1, struct cnode *cp2)
{
        if (cp1 == cp2)
                return (0);
        if (cp1 == NULL || cp2 == (struct cnode *)0xffffffff)
                return (1);
        if (cp2 == NULL || cp1 == (struct cnode *)0xffffffff)
                return (0);
        /*
         * Locking order is cnode address order.
         */
        return (cp1 < cp2);
}

/*
 * Acquire 4 cnode locks.
 *   - locked in cnode address order (lesser address first).
 *   - all or none of the locks are taken
 *   - only one lock taken per cnode (dup cnodes are skipped)
 *   - some of the cnode pointers may be null
 */
int
hfs_lockfour(struct cnode *cp1, struct cnode *cp2, struct cnode *cp3,
             struct cnode *cp4, enum hfslocktype locktype, struct cnode **error_cnode)
{
        struct cnode * a[3];
        struct cnode * b[3];
        struct cnode * list[4];
        struct cnode * tmp;
        int i, j, k;
        int error;
        if (error_cnode) {
                *error_cnode = NULL;
        }

        if (hfs_isordered(cp1, cp2)) {
                a[0] = cp1; a[1] = cp2;
        } else {
                a[0] = cp2; a[1] = cp1;
        }
        if (hfs_isordered(cp3, cp4)) {
                b[0] = cp3; b[1] = cp4;
        } else {
                b[0] = cp4; b[1] = cp3;
        }
        a[2] = (struct cnode *)0xffffffff;  /* sentinel value */
        b[2] = (struct cnode *)0xffffffff;  /* sentinel value */

        /*
         * Build the lock list, skipping over duplicates
         */
        for (i = 0, j = 0, k = 0; (i < 2 || j < 2); ) {
                tmp = hfs_isordered(a[i], b[j]) ? a[i++] : b[j++];
                if (k == 0 || tmp != list[k-1])
                        list[k++] = tmp;
        }

        /*
         * Now we can lock using list[0 - k].
         * Skip over NULL entries.
         */
        for (i = 0; i < k; ++i) {
                if (list[i])
                        if ((error = hfs_lock(list[i], locktype))) {
                                /* Only stuff error_cnode if requested */
                                if (error_cnode) {
                                        *error_cnode = list[i];
                                }
                                /* Drop any locks we acquired. */
                                while (--i >= 0) {
                                        if (list[i])
                                                hfs_unlock(list[i]);
                                }
                                return (error);
                        }
        }
        return (0);
}


/*
 * Unlock a cnode.
 */
void
hfs_unlock(struct cnode *cp)
{
        vnode_t rvp = NULLVP;
        vnode_t vp = NULLVP;
        u_int32_t c_flag;
        void *lockowner;

        /*
         * Only the extents and bitmap file's support lock recursion.
         */
        if ((cp->c_fileid == kHFSExtentsFileID) ||
            (cp->c_fileid == kHFSAllocationFileID)) {
                if (--cp->c_syslockcount > 0) {
                        return;
                }
        }
        c_flag = cp->c_flag;
        cp->c_flag &= ~(C_NEED_DVNODE_PUT | C_NEED_RVNODE_PUT | C_NEED_DATA_SETSIZE | C_NEED_RSRC_SETSIZE);

        if (c_flag & (C_NEED_DVNODE_PUT | C_NEED_DATA_SETSIZE)) {
                vp = cp->c_vp;
        }
        if (c_flag & (C_NEED_RVNODE_PUT | C_NEED_RSRC_SETSIZE)) {
                rvp = cp->c_rsrc_vp;
        }

        lockowner = cp->c_lockowner;
        if (lockowner == current_thread()) {
            cp->c_lockowner = NULL;
            lck_rw_unlock_exclusive(&cp->c_rwlock);
        } else {
            lck_rw_unlock_shared(&cp->c_rwlock);
        }

        /* Perform any vnode post processing after cnode lock is dropped. */
        if (vp) {
                if (c_flag & C_NEED_DATA_SETSIZE)
                        ubc_setsize(vp, 0);
                if (c_flag & C_NEED_DVNODE_PUT)
                        vnode_put(vp);
        }
        if (rvp) {
                if (c_flag & C_NEED_RSRC_SETSIZE)
                        ubc_setsize(rvp, 0);
                if (c_flag & C_NEED_RVNODE_PUT)
                        vnode_put(rvp);
        }
}

/*
 * Unlock a pair of cnodes.
 */
void
hfs_unlockpair(struct cnode *cp1, struct cnode *cp2)
{
        hfs_unlock(cp1);
        if (cp2 != cp1)
                hfs_unlock(cp2);
}

/*
 * Unlock a group of cnodes.
 */
void
hfs_unlockfour(struct cnode *cp1, struct cnode *cp2, struct cnode *cp3, struct cnode *cp4)
{
        struct cnode * list[4];
        int i, k = 0;

        if (cp1) {
                hfs_unlock(cp1);
                list[k++] = cp1;
        }
        if (cp2) {
                for (i = 0; i < k; ++i) {
                        if (list[i] == cp2)
                                goto skip1;
                }
                hfs_unlock(cp2);
                list[k++] = cp2;
        }
skip1:
        if (cp3) {
                for (i = 0; i < k; ++i) {
                        if (list[i] == cp3)
                                goto skip2;
                }
                hfs_unlock(cp3);
                list[k++] = cp3;
        }
skip2:
        if (cp4) {
                for (i = 0; i < k; ++i) {
                        if (list[i] == cp4)
                                return;
                }
                hfs_unlock(cp4);
        }
}


/*
 * Protect a cnode against a truncation.
 *
 * Used mainly by read/write since they don't hold the
 * cnode lock across calls to the cluster layer.
 *
 * The process doing a truncation must take the lock
 * exclusive. The read/write processes can take it
 * shared.  The locktype argument is the same as supplied to
 * hfs_lock.
 */
void
hfs_lock_truncate(struct cnode *cp, enum hfslocktype locktype)
{
        void * thread = current_thread();

        if (cp->c_truncatelockowner == thread) {
                /* 
                 * Only HFS_RECURSE_TRUNCLOCK is allowed to recurse.
                 * 
                 * This is needed on the hfs_vnop_pagein path where we need to ensure
                 * the file does not change sizes while we are paging in.  However,
                 * we may already hold the lock exclusive due to another 
                 * VNOP from earlier in the call stack.  So if we already hold 
                 * the truncate lock exclusive, allow it to proceed, but ONLY if 
                 * it's in the recursive case.
                 */
                if (locktype != HFS_RECURSE_TRUNCLOCK) {
                        panic("hfs_lock_truncate: cnode %p locked!", cp);
                }
        }
        /* HFS_RECURSE_TRUNCLOCK takes a shared lock if it is not already locked */
        else if ((locktype == HFS_SHARED_LOCK) || (locktype == HFS_RECURSE_TRUNCLOCK)) {
                lck_rw_lock_shared(&cp->c_truncatelock);
                cp->c_truncatelockowner = HFS_SHARED_OWNER;
        }
        else { /* must be an HFS_EXCLUSIVE_LOCK */
                lck_rw_lock_exclusive(&cp->c_truncatelock);
                cp->c_truncatelockowner = thread;
        }
}


/*
 * Attempt to get the truncate lock.  If it cannot be acquired, error out.
 * This function is needed in the degenerate hfs_vnop_pagein during force unmount
 * case.  To prevent deadlocks while a VM copy object is moving pages, HFS vnop pagein will
 * temporarily need to disable V2 semantics.  
 */
int hfs_try_trunclock (struct cnode *cp, enum hfslocktype locktype) {
        void * thread = current_thread();
        boolean_t didlock = false;

        if (cp->c_truncatelockowner == thread) {
                /* 
                 * Only HFS_RECURSE_TRUNCLOCK is allowed to recurse.
                 * 
                 * This is needed on the hfs_vnop_pagein path where we need to ensure
                 * the file does not change sizes while we are paging in.  However,
                 * we may already hold the lock exclusive due to another 
                 * VNOP from earlier in the call stack.  So if we already hold 
                 * the truncate lock exclusive, allow it to proceed, but ONLY if 
                 * it's in the recursive case.
                 */
                if (locktype != HFS_RECURSE_TRUNCLOCK) {
                        panic("hfs_lock_truncate: cnode %p locked!", cp);
                }
        }
        /* HFS_RECURSE_TRUNCLOCK takes a shared lock if it is not already locked */
        else if ((locktype == HFS_SHARED_LOCK) || (locktype == HFS_RECURSE_TRUNCLOCK)) {
                didlock = lck_rw_try_lock(&cp->c_truncatelock, LCK_RW_TYPE_SHARED);
                if (didlock) {
                        cp->c_truncatelockowner = HFS_SHARED_OWNER;
                }
        }
        else { /* must be an HFS_EXCLUSIVE_LOCK */
                didlock = lck_rw_try_lock (&cp->c_truncatelock, LCK_RW_TYPE_EXCLUSIVE);
                if (didlock) {
                        cp->c_truncatelockowner = thread;
                }
        }
        
        return didlock;
}


/*
 * Unlock the truncate lock, which protects against size changes.
 * 
 * The been_recursed argument is used when we may need to return
 * from this function without actually unlocking the truncate lock.
 */
void
hfs_unlock_truncate(struct cnode *cp, int been_recursed)
{
        void *thread = current_thread();        

        /*
         * If been_recursed is nonzero AND the current lock owner of the
         * truncate lock is our current thread, then we must have recursively
         * taken the lock earlier on.  If the lock were unlocked, 
         * HFS_RECURSE_TRUNCLOCK took a shared lock and it would fall through
         * to the SHARED case below. 
         *
         * If been_recursed is zero (most of the time) then we check the 
         * lockowner field to infer whether the lock was taken exclusively or
         * shared in order to know what underlying lock routine to call. 
         */
        if (been_recursed) {
                if (cp->c_truncatelockowner == thread) {
                        return; 
                }
        }

        /* HFS_LOCK_EXCLUSIVE */
        if (thread == cp->c_truncatelockowner) {
                cp->c_truncatelockowner = NULL;
                lck_rw_unlock_exclusive(&cp->c_truncatelock);
        }
        /* HFS_LOCK_SHARED */
        else {
                lck_rw_unlock_shared(&cp->c_truncatelock);
        }
}