[apple/xnu.git] / bsd / hfs / hfs_chash.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,
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 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
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/*
 * Copyright (c) 1982, 1986, 1989, 1991, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *        notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *        notice, this list of conditions and the following disclaimer in the
 *        documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *        must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *        may be used to endorse or promote products derived from this software
 *        without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.      IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)hfs_chash.c
 *      derived from @(#)ufs_ihash.c    8.7 (Berkeley) 5/17/95
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/queue.h>


#include "hfs.h"        /* XXX bringup */
#include "hfs_cnode.h"

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

lck_grp_t * chash_lck_grp;
lck_grp_attr_t * chash_lck_grp_attr;
lck_attr_t * chash_lck_attr;


#define CNODEHASH(hfsmp, inum) (&hfsmp->hfs_cnodehashtbl[(inum) & hfsmp->hfs_cnodehash])


/*
 * Initialize cnode hash table.
 */
__private_extern__
void
hfs_chashinit()
{
        chash_lck_grp_attr= lck_grp_attr_alloc_init();
        chash_lck_grp  = lck_grp_alloc_init("cnode_hash", chash_lck_grp_attr);
        chash_lck_attr = lck_attr_alloc_init();
}

static void hfs_chash_lock(struct hfsmount *hfsmp) 
{
        lck_mtx_lock(&hfsmp->hfs_chash_mutex);
}

static void hfs_chash_lock_spin(struct hfsmount *hfsmp) 
{
        lck_mtx_lock_spin(&hfsmp->hfs_chash_mutex);
}

static void hfs_chash_lock_convert (__unused struct hfsmount *hfsmp)
{
        lck_mtx_convert_spin(&hfsmp->hfs_chash_mutex);
}

static void hfs_chash_unlock(struct hfsmount *hfsmp) 
{
        lck_mtx_unlock(&hfsmp->hfs_chash_mutex);
}

__private_extern__
void
hfs_chashinit_finish(struct hfsmount *hfsmp)
{
        lck_mtx_init(&hfsmp->hfs_chash_mutex, chash_lck_grp, chash_lck_attr);

        hfsmp->hfs_cnodehashtbl = hashinit(desiredvnodes / 4, M_HFSMNT, &hfsmp->hfs_cnodehash);
}

__private_extern__
void
hfs_delete_chash(struct hfsmount *hfsmp)
{
        lck_mtx_destroy(&hfsmp->hfs_chash_mutex, chash_lck_grp);

        FREE(hfsmp->hfs_cnodehashtbl, M_HFSMNT);
}


/*
 * Use the device, inum pair to find the incore cnode.
 *
 * If it is in core, but locked, wait for it.
 */
struct vnode *
hfs_chash_getvnode(struct hfsmount *hfsmp, ino_t inum, int wantrsrc, int skiplock, int allow_deleted)
{
        struct cnode *cp;
        struct vnode *vp;
        int error;
        u_int32_t vid;

        /* 
         * Go through the hash list
         * If a cnode is in the process of being cleaned out or being
         * allocated, wait for it to be finished and then try again.
         */
loop:
        hfs_chash_lock_spin(hfsmp);

        for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
                if (cp->c_fileid != inum)
                        continue;
                /* Wait if cnode is being created or reclaimed. */
                if (ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
                        SET(cp->c_hflag, H_WAITING);

                        (void) msleep(cp, &hfsmp->hfs_chash_mutex, PDROP | PINOD,
                                      "hfs_chash_getvnode", 0);
                        goto loop;
                }
                /* Obtain the desired vnode. */
                vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
                if (vp == NULLVP)
                        goto exit;

                vid = vnode_vid(vp);
                hfs_chash_unlock(hfsmp);

                if ((error = vnode_getwithvid(vp, vid))) {
                        /*
                         * If vnode is being reclaimed, or has
                         * already changed identity, no need to wait
                         */
                        return (NULL);
                }
                if (!skiplock && hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT) != 0) {
                        vnode_put(vp);
                        return (NULL);
                }

                /*
                 * Skip cnodes that are not in the name space anymore
                 * we need to check with the cnode lock held because
                 * we may have blocked acquiring the vnode ref or the
                 * lock on the cnode which would allow the node to be
                 * unlinked
                 */
                if (!allow_deleted) {
                        if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
                                if (!skiplock) {
                                        hfs_unlock(cp);
                                }
                                vnode_put(vp);
                                return (NULL);
                        }                       
                }
                return (vp);
        }
exit:
        hfs_chash_unlock(hfsmp);
        return (NULL);
}


/*
 * Use the device, fileid pair to snoop an incore cnode.
 *
 * A cnode can exists in chash even after it has been 
 * deleted from the catalog, so this function returns 
 * ENOENT if C_NOEXIST is set in the cnode's flag.
 * 
 */
int
hfs_chash_snoop(struct hfsmount *hfsmp, ino_t inum, int existence_only, 
                                int (*callout)(const cnode_t *cp, void *), void * arg)
{
        struct cnode *cp;
        int result = ENOENT;

        /* 
         * Go through the hash list
         * If a cnode is in the process of being cleaned out or being
         * allocated, wait for it to be finished and then try again.
         */
        hfs_chash_lock(hfsmp);

        for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
                if (cp->c_fileid != inum)
                        continue;
        
                /*
                 * Under normal circumstances, we would want to return ENOENT if a cnode is in
                 * the hash and it is marked C_NOEXISTS or C_DELETED.  However, if the CNID
                 * namespace has wrapped around, then we have the possibility of collisions.  
                 * In that case, we may use this function to validate whether or not we 
                 * should trust the nextCNID value in the hfs mount point.  
                 * 
                 * If we didn't do this, then it would be possible for a cnode that is no longer backed
                 * by anything on-disk (C_NOEXISTS) to still exist in the hash along with its
                 * vnode.  The cat_create routine could then create a new entry in the catalog
                 * re-using that CNID.  Then subsequent hfs_getnewvnode calls will repeatedly fail
                 * trying to look it up/validate it because it is marked C_NOEXISTS.  So we want
                 * to prevent that from happening as much as possible.
                 */
                if (existence_only) {
                        result = 0;
                        break;
                }

                /* Skip cnodes that have been removed from the catalog */
                if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
                        result = EACCES;
                        break;
                }

                /* Skip cnodes being created or reclaimed. */
                if (!ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
                        result = callout(cp, arg);
                }
                break;
        }
        hfs_chash_unlock(hfsmp);

        return (result);
}


/*
 * Use the device, fileid pair to find the incore cnode.
 * If no cnode if found one is created
 *
 * If it is in core, but locked, wait for it.
 *
 * If the cnode is C_DELETED, then return NULL since that 
 * inum is no longer valid for lookups (open-unlinked file).
 *
 * If the cnode is C_DELETED but also marked C_RENAMED, then that means
 * the cnode was renamed over and a new entry exists in its place.  The caller
 * should re-drive the lookup to get the newer entry.  In that case, we'll still
 * return NULL for the cnode, but also return GNV_CHASH_RENAMED in the output flags
 * of this function to indicate the caller that they should re-drive.
 */
struct cnode *
hfs_chash_getcnode(struct hfsmount *hfsmp, ino_t inum, struct vnode **vpp, 
                                   int wantrsrc, int skiplock, int *out_flags, int *hflags)
{
        struct cnode    *cp;
        struct cnode    *ncp = NULL;
        vnode_t         vp;
        u_int32_t       vid;

        /* 
         * Go through the hash list
         * If a cnode is in the process of being cleaned out or being
         * allocated, wait for it to be finished and then try again.
         */
loop:
        hfs_chash_lock_spin(hfsmp);

loop_with_lock:
        for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
                if (cp->c_fileid != inum)
                        continue;
                /*
                 * Wait if cnode is being created, attached to or reclaimed.
                 */
                if (ISSET(cp->c_hflag, H_ALLOC | H_ATTACH | H_TRANSIT)) {
                        SET(cp->c_hflag, H_WAITING);

                        (void) msleep(cp, &hfsmp->hfs_chash_mutex, PINOD,
                                      "hfs_chash_getcnode", 0);
                        goto loop_with_lock;
                }
                vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
                if (vp == NULL) {
                        /*
                         * The desired vnode isn't there so tag the cnode.
                         */
                        SET(cp->c_hflag, H_ATTACH);
                        *hflags |= H_ATTACH;

                        hfs_chash_unlock(hfsmp);
                } else {
                        vid = vnode_vid(vp);

                        hfs_chash_unlock(hfsmp);

                        if (vnode_getwithvid(vp, vid))
                                goto loop;
                }
                if (ncp) {
                        /*
                         * someone else won the race to create
                         * this cnode and add it to the hash
                         * just dump our allocation
                         */
                        FREE_ZONE(ncp, sizeof(struct cnode), M_HFSNODE);
                        ncp = NULL;
                }

                if (!skiplock) {
                        hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_ALLOW_NOEXISTS);
                }

                /*
                 * Skip cnodes that are not in the name space anymore
                 * we need to check with the cnode lock held because
                 * we may have blocked acquiring the vnode ref or the
                 * lock on the cnode which would allow the node to be
                 * unlinked.
                 *
                 * Don't return a cnode in this case since the inum
                 * is no longer valid for lookups.
                 */
                if ((cp->c_flag & (C_NOEXISTS | C_DELETED)) && !wantrsrc) {
                        int renamed = 0;
                        if (cp->c_flag & C_RENAMED) {
                                renamed = 1;
                        }
                        if (!skiplock)
                                hfs_unlock(cp);
                        if (vp != NULLVP) {
                                vnode_put(vp);
                        } else {
                                hfs_chash_lock_spin(hfsmp);
                                CLR(cp->c_hflag, H_ATTACH);
                                *hflags &= ~H_ATTACH;
                                if (ISSET(cp->c_hflag, H_WAITING)) {
                                        CLR(cp->c_hflag, H_WAITING);
                                        wakeup((caddr_t)cp);
                                }
                                hfs_chash_unlock(hfsmp);
                        }
                        vp = NULL;
                        cp = NULL;
                        if (renamed) {
                                *out_flags = GNV_CHASH_RENAMED;
                        }
                }
                *vpp = vp;
                return (cp);
        }

        /* 
         * Allocate a new cnode
         */
        if (skiplock && !wantrsrc)
                panic("%s - should never get here when skiplock is set \n", __FUNCTION__);

        if (ncp == NULL) {
                hfs_chash_unlock(hfsmp);

                MALLOC_ZONE(ncp, struct cnode *, sizeof(struct cnode), M_HFSNODE, M_WAITOK);
                /*
                 * since we dropped the chash lock, 
                 * we need to go back and re-verify
                 * that this node hasn't come into 
                 * existence...
                 */
                goto loop;
        }
        hfs_chash_lock_convert(hfsmp);

        bzero(ncp, sizeof(struct cnode));
        SET(ncp->c_hflag, H_ALLOC);
        *hflags |= H_ALLOC;
        ncp->c_fileid = inum;
        TAILQ_INIT(&ncp->c_hintlist); /* make the list empty */
        TAILQ_INIT(&ncp->c_originlist);

        lck_rw_init(&ncp->c_rwlock, hfs_rwlock_group, hfs_lock_attr);
        if (!skiplock)
                (void) hfs_lock(ncp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT);

        /* Insert the new cnode with it's H_ALLOC flag set */
        LIST_INSERT_HEAD(CNODEHASH(hfsmp, inum), ncp, c_hash);
        hfs_chash_unlock(hfsmp);

        *vpp = NULL;
        return (ncp);
}


__private_extern__
void
hfs_chashwakeup(struct hfsmount *hfsmp, struct cnode *cp, int hflags)
{
        hfs_chash_lock_spin(hfsmp);

        CLR(cp->c_hflag, hflags);

        if (ISSET(cp->c_hflag, H_WAITING)) {
                CLR(cp->c_hflag, H_WAITING);
                wakeup((caddr_t)cp);
        }
        hfs_chash_unlock(hfsmp);
}


/*
 * Re-hash two cnodes in the hash table.
 */
__private_extern__
void
hfs_chash_rehash(struct hfsmount *hfsmp, struct cnode *cp1, struct cnode *cp2)
{
        hfs_chash_lock_spin(hfsmp);

        LIST_REMOVE(cp1, c_hash);
        LIST_REMOVE(cp2, c_hash);
        LIST_INSERT_HEAD(CNODEHASH(hfsmp, cp1->c_fileid), cp1, c_hash);
        LIST_INSERT_HEAD(CNODEHASH(hfsmp, cp2->c_fileid), cp2, c_hash);

        hfs_chash_unlock(hfsmp);
}


/*
 * Remove a cnode from the hash table.
 */
__private_extern__
int
hfs_chashremove(struct hfsmount *hfsmp, struct cnode *cp)
{
        hfs_chash_lock_spin(hfsmp);

        /* Check if a vnode is getting attached */
        if (ISSET(cp->c_hflag, H_ATTACH)) {
                hfs_chash_unlock(hfsmp);
                return (EBUSY);
        }
        if (cp->c_hash.le_next || cp->c_hash.le_prev) {
            LIST_REMOVE(cp, c_hash);
            cp->c_hash.le_next = NULL;
            cp->c_hash.le_prev = NULL;
        }
        hfs_chash_unlock(hfsmp);

        return (0);
}

/*
 * Remove a cnode from the hash table and wakeup any waiters.
 */
__private_extern__
void
hfs_chash_abort(struct hfsmount *hfsmp, struct cnode *cp)
{
        hfs_chash_lock_spin(hfsmp);

        LIST_REMOVE(cp, c_hash);
        cp->c_hash.le_next = NULL;
        cp->c_hash.le_prev = NULL;

        CLR(cp->c_hflag, H_ATTACH | H_ALLOC);
        if (ISSET(cp->c_hflag, H_WAITING)) {
                CLR(cp->c_hflag, H_WAITING);
                wakeup((caddr_t)cp);
        }
        hfs_chash_unlock(hfsmp);
}


/*
 * mark a cnode as in transition
 */
__private_extern__
void
hfs_chash_mark_in_transit(struct hfsmount *hfsmp, struct cnode *cp)
{
        hfs_chash_lock_spin(hfsmp);

        SET(cp->c_hflag, H_TRANSIT);

        hfs_chash_unlock(hfsmp);
}

/* Search a cnode in the hash.  This function does not return cnode which 
 * are getting created, destroyed or in transition.  Note that this function
 * does not acquire the cnode hash mutex, and expects the caller to acquire it.
 * On success, returns pointer to the cnode found.  On failure, returns NULL.
 */
static 
struct cnode *
hfs_chash_search_cnid(struct hfsmount *hfsmp, cnid_t cnid) 
{
        struct cnode *cp;

        for (cp = CNODEHASH(hfsmp, cnid)->lh_first; cp; cp = cp->c_hash.le_next) {
                if (cp->c_fileid == cnid) {
                        break;
                }
        }

        /* If cnode is being created or reclaimed, return error. */
        if (cp && ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
                cp = NULL;
        }

        return cp;
}

/* Search a cnode corresponding to given device and ID in the hash.  If the 
 * found cnode has kHFSHasChildLinkBit cleared, set it.  If the cnode is not 
 * found, no new cnode is created and error is returned.
 * 
 * Return values - 
 *      -1 : The cnode was not found.
 *       0 : The cnode was found, and the kHFSHasChildLinkBit was already set.
 *       1 : The cnode was found, the kHFSHasChildLinkBit was not set, and the 
 *           function had to set that bit.
 */
__private_extern__ 
int
hfs_chash_set_childlinkbit(struct hfsmount *hfsmp, cnid_t cnid)
{
        int retval = -1;
        struct cnode *cp;

        hfs_chash_lock_spin(hfsmp);

        cp = hfs_chash_search_cnid(hfsmp, cnid);
        if (cp) {
                if (cp->c_attr.ca_recflags & kHFSHasChildLinkMask) {
                        retval = 0;
                } else {
                        cp->c_attr.ca_recflags |= kHFSHasChildLinkMask;
                        retval = 1;
                }
        }
        hfs_chash_unlock(hfsmp);

        return retval;
}