HAMMER 27/many: Major surgery - change allocation model

[dragonfly.git] / sys / vfs / hammer / hammer_object.c

/*
 * Copyright (c) 2007 The DragonFly Project.  All rights reserved.
 * 
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 * 
 * 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. Neither the name of The DragonFly Project 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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.
 * 
 * $DragonFly: src/sys/vfs/hammer/hammer_object.c,v 1.29 2008/02/08 08:30:59 dillon Exp $
 */

#include "hammer.h"

static int hammer_mem_add(hammer_transaction_t trans, hammer_record_t record);
static int hammer_mem_lookup(hammer_cursor_t cursor, hammer_inode_t ip);
static int hammer_mem_first(hammer_cursor_t cursor, hammer_inode_t ip);

/*
 * Red-black tree support.
 */
static int
hammer_rec_rb_compare(hammer_record_t rec1, hammer_record_t rec2)
{
        if (rec1->rec.base.base.rec_type < rec2->rec.base.base.rec_type)
                return(-1);
        if (rec1->rec.base.base.rec_type > rec2->rec.base.base.rec_type)
                return(1);

        if (rec1->rec.base.base.key < rec2->rec.base.base.key)
                return(-1);
        if (rec1->rec.base.base.key > rec2->rec.base.base.key)
                return(1);

        if (rec1->rec.base.base.create_tid == 0) {
                if (rec2->rec.base.base.create_tid == 0)
                        return(0);
                return(1);
        }
        if (rec2->rec.base.base.create_tid == 0)
                return(-1);

        if (rec1->rec.base.base.create_tid < rec2->rec.base.base.create_tid)
                return(-1);
        if (rec1->rec.base.base.create_tid > rec2->rec.base.base.create_tid)
                return(1);
        return(0);
}

static int
hammer_rec_compare(hammer_base_elm_t info, hammer_record_t rec)
{
        if (info->rec_type < rec->rec.base.base.rec_type)
                return(-3);
        if (info->rec_type > rec->rec.base.base.rec_type)
                return(3);

        if (info->key < rec->rec.base.base.key)
                return(-2);
        if (info->key > rec->rec.base.base.key)
                return(2);

        if (info->create_tid == 0) {
                if (rec->rec.base.base.create_tid == 0)
                        return(0);
                return(1);
        }
        if (rec->rec.base.base.create_tid == 0)
                return(-1);
        if (info->create_tid < rec->rec.base.base.create_tid)
                return(-1);
        if (info->create_tid > rec->rec.base.base.create_tid)
                return(1);
        return(0);
}

/*
 * RB_SCAN comparison code for hammer_mem_first().  The argument order
 * is reversed so the comparison result has to be negated.  key_beg and
 * key_end are both range-inclusive.
 *
 * The creation timestamp can cause hammer_rec_compare() to return -1 or +1.
 * These do not stop the scan.
 *
 * Localized deletions are not cached in-memory.
 */
static
int
hammer_rec_scan_cmp(hammer_record_t rec, void *data)
{
        hammer_cursor_t cursor = data;
        int r;

        r = hammer_rec_compare(&cursor->key_beg, rec);
        if (r > 1)
                return(-1);
        r = hammer_rec_compare(&cursor->key_end, rec);
        if (r < -1)
                return(1);
        return(0);
}

RB_GENERATE(hammer_rec_rb_tree, hammer_record, rb_node, hammer_rec_rb_compare);
RB_GENERATE_XLOOKUP(hammer_rec_rb_tree, INFO, hammer_record, rb_node,
                    hammer_rec_compare, hammer_base_elm_t);

/*
 * Allocate a record for the caller to finish filling in.  The record is
 * returned referenced.
 */
hammer_record_t
hammer_alloc_mem_record(hammer_inode_t ip, int32_t rec_len)
{
        hammer_record_t record;

        ++hammer_count_records;
        record = kmalloc(sizeof(*record), M_HAMMER, M_WAITOK|M_ZERO);
        record->ip = ip;
        record->rec.base.base.btype = HAMMER_BTREE_TYPE_RECORD;
        record->rec_len = rec_len;
        hammer_ref(&record->lock);
        return (record);
}

/*
 * Release a memory record.  Records marked for deletion are immediately
 * removed from the RB-Tree but otherwise left intact until the last ref
 * goes away.
 */
void
hammer_rel_mem_record(struct hammer_record *record)
{
        hammer_unref(&record->lock);

        if (record->flags & HAMMER_RECF_DELETED) {
                if (record->flags & HAMMER_RECF_ONRBTREE) {
                        RB_REMOVE(hammer_rec_rb_tree, &record->ip->rec_tree,
                                  record);
                        record->flags &= ~HAMMER_RECF_ONRBTREE;
                }
                if (record->lock.refs == 0) {
                        if (record->flags & HAMMER_RECF_ALLOCDATA) {
                                --hammer_count_record_datas;
                                kfree(record->data, M_HAMMER);
                                record->flags &= ~HAMMER_RECF_ALLOCDATA;
                        }
                        record->data = NULL;
                        --hammer_count_records;
                        kfree(record, M_HAMMER);
                        return;
                }
        }

        /*
         * If someone wanted the record wake them up.
         */
        if (record->flags & HAMMER_RECF_WANTED) {
                record->flags &= ~HAMMER_RECF_WANTED;
                wakeup(record);
        }
}

/*
 * Lookup an in-memory record given the key specified in the cursor.  Works
 * just like hammer_btree_lookup() but operates on an inode's in-memory
 * record list.
 *
 * The lookup must fail if the record is marked for deferred deletion.
 */
static
int
hammer_mem_lookup(hammer_cursor_t cursor, hammer_inode_t ip)
{
        int error;

        if (cursor->iprec) {
                hammer_rel_mem_record(cursor->iprec);
                cursor->iprec = NULL;
        }
        if (cursor->ip) {
                hammer_rec_rb_tree_scan_info_done(&cursor->scan,
                                                  &cursor->ip->rec_tree);
        }
        cursor->ip = ip;
        hammer_rec_rb_tree_scan_info_link(&cursor->scan, &ip->rec_tree);
        cursor->scan.node = NULL;
        cursor->iprec = hammer_rec_rb_tree_RB_LOOKUP_INFO(
                                &ip->rec_tree, &cursor->key_beg);
        if (cursor->iprec == NULL) {
                error = ENOENT;
        } else {
                hammer_ref(&cursor->iprec->lock);
                error = 0;
        }
        return(error);
}

/*
 * hammer_mem_first() - locate the first in-memory record matching the
 * cursor.
 *
 * The RB_SCAN function we use is designed as a callback.  We terminate it
 * (return -1) as soon as we get a match.
 */
static
int
hammer_rec_scan_callback(hammer_record_t rec, void *data)
{
        hammer_cursor_t cursor = data;

        /*
         * We terminate on success, so this should be NULL on entry.
         */
        KKASSERT(cursor->iprec == NULL);

        /*
         * Skip if the record was marked deleted
         */
        if (rec->flags & HAMMER_RECF_DELETED)
                return(0);

        /*
         * Skip if not visible due to our as-of TID
         */
        if (cursor->flags & HAMMER_CURSOR_ASOF) {
                if (cursor->asof < rec->rec.base.base.create_tid)
                        return(0);
                if (rec->rec.base.base.delete_tid &&
                    cursor->asof >= rec->rec.base.base.delete_tid) {
                        return(0);
                }
        }

        /*
         * Block if currently being synchronized to disk, otherwise we
         * may get a duplicate.  Wakeup the syncer if it's stuck on
         * the record.
         */
        hammer_ref(&rec->lock);
        ++rec->blocked;
        while (rec->flags & HAMMER_RECF_SYNCING) {
                rec->flags |= HAMMER_RECF_WANTED;
                tsleep(rec, 0, "hmrrc2", 0);
        }
        --rec->blocked;

        /*
         * The record may have been deleted while we were blocked.
         */
        if (rec->flags & HAMMER_RECF_DELETED) {
                hammer_rel_mem_record(cursor->iprec);
                return(0);
        }

        /*
         * Set the matching record and stop the scan.
         */
        cursor->iprec = rec;
        return(-1);
}

static
int
hammer_mem_first(hammer_cursor_t cursor, hammer_inode_t ip)
{
        if (cursor->iprec) {
                hammer_rel_mem_record(cursor->iprec);
                cursor->iprec = NULL;
        }
        if (cursor->ip) {
                hammer_rec_rb_tree_scan_info_done(&cursor->scan,
                                                  &cursor->ip->rec_tree);
        }
        cursor->ip = ip;
        hammer_rec_rb_tree_scan_info_link(&cursor->scan, &ip->rec_tree);

        cursor->scan.node = NULL;
        hammer_rec_rb_tree_RB_SCAN(&ip->rec_tree, hammer_rec_scan_cmp,
                                   hammer_rec_scan_callback, cursor);

        /*
         * Adjust scan.node and keep it linked into the RB-tree so we can
         * hold the cursor through third party modifications of the RB-tree.
         */
        if (cursor->iprec) {
                cursor->scan.node = hammer_rec_rb_tree_RB_NEXT(cursor->iprec);
                return(0);
        }
        return(ENOENT);
}

void
hammer_mem_done(hammer_cursor_t cursor)
{
        if (cursor->ip) {
                hammer_rec_rb_tree_scan_info_done(&cursor->scan,
                                                  &cursor->ip->rec_tree);
                cursor->ip = NULL;
        }
        if (cursor->iprec) {
                hammer_rel_mem_record(cursor->iprec);
                cursor->iprec = NULL;
        }
}

/************************************************************************
 *                   HAMMER IN-MEMORY RECORD FUNCTIONS                  *
 ************************************************************************
 *
 * These functions manipulate in-memory records.  Such records typically
 * exist prior to being committed to disk or indexed via the on-disk B-Tree.
 */

/*
 * Add a directory entry (dip,ncp) which references inode (ip).
 *
 * Note that the low 32 bits of the namekey are set temporarily to create
 * a unique in-memory record, and may be modified a second time when the
 * record is synchronized to disk.  In particular, the low 32 bits cannot be
 * all 0's when synching to disk, which is not handled here.
 */
int
hammer_ip_add_directory(struct hammer_transaction *trans,
                     struct hammer_inode *dip, struct namecache *ncp,
                     struct hammer_inode *ip)
{
        hammer_record_t record;
        int error;
        int bytes;

        record = hammer_alloc_mem_record(dip, sizeof(struct hammer_entry_record));

        bytes = ncp->nc_nlen;   /* NOTE: terminating \0 is NOT included */
        if (++trans->hmp->namekey_iterator == 0)
                ++trans->hmp->namekey_iterator;

        record->rec.entry.base.base.obj_id = dip->obj_id;
        record->rec.entry.base.base.key =
                hammer_directory_namekey(ncp->nc_name, bytes);
        record->rec.entry.base.base.key += trans->hmp->namekey_iterator;
        record->rec.entry.base.base.create_tid = trans->tid;
        record->rec.entry.base.base.rec_type = HAMMER_RECTYPE_DIRENTRY;
        record->rec.entry.base.base.obj_type = ip->ino_rec.base.base.obj_type;
        record->rec.entry.obj_id = ip->obj_id;
        record->data = (void *)ncp->nc_name;
        record->rec.entry.base.data_len = bytes;
        ++ip->ino_rec.ino_nlinks;
        hammer_modify_inode(trans, ip, HAMMER_INODE_RDIRTY);
        /* NOTE: copies record->data */
        error = hammer_mem_add(trans, record);
        return(error);
}

/*
 * Delete the directory entry and update the inode link count.  The
 * cursor must be seeked to the directory entry record being deleted.
 *
 * NOTE: HAMMER_CURSOR_DELETE may not have been set.  XXX remove flag.
 *
 * This function can return EDEADLK requiring the caller to terminate
 * the cursor and retry.
 */
int
hammer_ip_del_directory(struct hammer_transaction *trans,
                     hammer_cursor_t cursor, struct hammer_inode *dip,
                     struct hammer_inode *ip)
{
        int error;

        error = hammer_ip_delete_record(cursor, trans->tid);

        /*
         * One less link.  The file may still be open in the OS even after
         * all links have gone away so we only try to sync if the OS has
         * no references and nlinks falls to 0.
         *
         * We have to terminate the cursor before syncing the inode to
         * avoid deadlocking against ourselves.
         */
        if (error == 0) {
                --ip->ino_rec.ino_nlinks;
                hammer_modify_inode(trans, ip, HAMMER_INODE_RDIRTY);
                if (ip->ino_rec.ino_nlinks == 0 &&
                    (ip->vp == NULL || (ip->vp->v_flag & VINACTIVE))) {
                        hammer_done_cursor(cursor);
                        hammer_sync_inode(ip, MNT_NOWAIT, 1);
                }

        }
        return(error);
}

/*
 * Add a record to an inode.
 *
 * The caller must allocate the record with hammer_alloc_mem_record(ip) and
 * initialize the following additional fields:
 *
 * record->rec.entry.base.base.key
 * record->rec.entry.base.base.rec_type
 * record->rec.entry.base.base.data_len
 * record->data         (a copy will be kmalloc'd if it cannot be embedded)
 */
int
hammer_ip_add_record(struct hammer_transaction *trans, hammer_record_t record)
{
        hammer_inode_t ip = record->ip;
        int error;

        record->rec.base.base.obj_id = ip->obj_id;
        record->rec.base.base.create_tid = trans->tid;
        record->rec.base.base.obj_type = ip->ino_rec.base.base.obj_type;

        hammer_modify_inode(trans, ip, HAMMER_INODE_RDIRTY);
        /* NOTE: copies record->data */
        error = hammer_mem_add(trans, record);
        return(error);
}

/*
 * Sync data from a buffer cache buffer (typically) to the filesystem.  This
 * is called via the strategy called from a cached data source.  This code
 * is responsible for actually writing a data record out to the disk.
 *
 * This can only occur non-historically (i.e. 'current' data only).
 */
int
hammer_ip_sync_data(hammer_transaction_t trans, hammer_inode_t ip,
                       int64_t offset, void *data, int bytes)
{
        struct hammer_cursor cursor;
        hammer_record_ondisk_t rec;
        union hammer_btree_elm elm;
        hammer_off_t rec_offset;
        hammer_off_t data_offset;
        void *bdata1, *bdata2;
        int32_t data2_index;
        int error;

        KKASSERT((offset & HAMMER_BUFMASK) == 0);
        KKASSERT((bytes & HAMMER_BUFMASK) == 0);
retry:
        error = hammer_init_cursor_hmp(&cursor, &ip->cache[0], ip->hmp);
        if (error)
                return(error);
        cursor.key_beg.obj_id = ip->obj_id;
        cursor.key_beg.key = offset + bytes;
        cursor.key_beg.create_tid = trans->tid;
        cursor.key_beg.delete_tid = 0;
        cursor.key_beg.rec_type = HAMMER_RECTYPE_DATA;
        cursor.asof = trans->tid;
        cursor.flags |= HAMMER_CURSOR_INSERT;

        /*
         * Issue a lookup to position the cursor.
         */
        error = hammer_btree_lookup(&cursor);
        if (error == 0) {
                kprintf("hammer_ip_sync_data: duplicate data at (%lld,%d)\n",
                        offset, bytes);
                hammer_print_btree_elm(&cursor.node->ondisk->elms[cursor.index],
                                       HAMMER_BTREE_TYPE_LEAF, cursor.index);
                error = EIO;
        }
        if (error != ENOENT)
                goto done;

        /*
         * Allocate record and data space.  HAMMER_RECTYPE_DATA records
         * can cross buffer boundaries so we may have to split our bcopy.
         */
        rec = hammer_alloc_record(ip->hmp, &rec_offset, HAMMER_RECTYPE_DATA,
                                  sizeof(rec->data), &cursor.record_buffer,
                                  &data_offset, bytes, 
                                  &bdata1, &bdata2, &data2_index,
                                  &cursor.data_buffer, &error);
        if (rec == NULL)
                goto done;

        /*
         * Fill everything in and insert our B-Tree node.
         *
         * NOTE: hammer_alloc_record() has already marked the related
         * buffers as modified.  If we do it again we will generate
         * unnecessary undo elements.
         */
        rec->base.base.btype = HAMMER_BTREE_TYPE_RECORD;
        rec->base.base.obj_id = ip->obj_id;
        rec->base.base.key = offset + bytes;
        rec->base.base.create_tid = trans->tid;
        rec->base.base.delete_tid = 0;
        rec->base.base.rec_type = HAMMER_RECTYPE_DATA;
        rec->base.head.hdr_crc = crc32(data, bytes);
        KKASSERT(rec->base.data_off == data_offset);
        KKASSERT(rec->base.data_len == bytes);

        if (data2_index < bytes) {
                bcopy(data, bdata1, data2_index);
                bcopy((char *)data + data2_index, bdata2, bytes - data2_index);
        } else {
                bcopy(data, bdata1, bytes);
        }

        elm.leaf.base = rec->base.base;
        elm.leaf.rec_offset = rec_offset;
        elm.leaf.data_offset = rec->base.data_off;
        elm.leaf.data_len = bytes;
        elm.leaf.data_crc = rec->base.head.hdr_crc;

        /*
         * Data records can wind up on-disk before the inode itself is
         * on-disk.  One must assume data records may be on-disk if either
         * HAMMER_INODE_DONDISK or HAMMER_INODE_ONDISK is set
         */
        ip->flags |= HAMMER_INODE_DONDISK;

        error = hammer_btree_insert(&cursor, &elm);
        if (error == 0)
                goto done;

        /*
         * If we fail we may be able to unwind the allocation.
         */
        rec->base.head.hdr_type |= HAMMER_HEAD_TYPEF_FREED;
        hammer_unwind_fifo(ip->hmp, rec_offset);
done:
        hammer_done_cursor(&cursor);
        if (error == EDEADLK)
                goto retry;
        return(error);
}

/*
 * Sync an in-memory record to the disk.  this is typically called via fsync
 * from a cached record source.  This code is responsible for actually
 * writing a record out to the disk.
 */
int
hammer_ip_sync_record(hammer_record_t record)
{
        struct hammer_cursor cursor;
        hammer_record_ondisk_t rec;
        hammer_mount_t hmp;
        union hammer_btree_elm elm;
        hammer_off_t rec_offset;
        hammer_off_t data_offset;
        void *bdata1;
        int32_t alloc_data_len;
        int error;

        hmp = record->ip->hmp;
retry:
        /*
         * If the record has been deleted or is being synchronized, stop.
         * Interlock with the syncing flag.
         */
        if (record->flags & (HAMMER_RECF_DELETED | HAMMER_RECF_SYNCING))
                return(0);
        record->flags |= HAMMER_RECF_SYNCING;

        /*
         * If someone other then us is referencing the record and not
         * blocking waiting for us, we have to wait until they finish.
         *
         * It is possible the record got destroyed while we were blocked.
         */
        if (record->lock.refs > record->blocked + 1) {
                while (record->lock.refs > record->blocked + 1) {
                        record->flags |= HAMMER_RECF_WANTED;
                        tsleep(record, 0, "hmrrc1", 0);
                }
                if (record->flags & HAMMER_RECF_DELETED)
                        return(0);
        }

        /*
         * Get a cursor
         */
        error = hammer_init_cursor_hmp(&cursor, &record->ip->cache[0], hmp);
        if (error)
                return(error);
        cursor.key_beg = record->rec.base.base;
        cursor.flags |= HAMMER_CURSOR_INSERT;

        /*
         * Issue a lookup to position the cursor and locate the cluster.  The
         * target key should not exist.  If we are creating a directory entry
         * we may have to iterate the low 32 bits of the key to find an unused
         * key.
         */
        for (;;) {
                error = hammer_btree_lookup(&cursor);
                if (error)
                        break;
                if (record->rec.base.base.rec_type != HAMMER_RECTYPE_DIRENTRY) {
                        kprintf("hammer_ip_sync_record: duplicate rec "
                                "at (%016llx)\n", record->rec.base.base.key);
                        Debugger("duplicate record1");
                        error = EIO;
                        break;
                }
                if (++hmp->namekey_iterator == 0)
                        ++hmp->namekey_iterator;
                record->rec.base.base.key &= ~(0xFFFFFFFFLL);
                record->rec.base.base.key |= hmp->namekey_iterator;
                cursor.key_beg.key = record->rec.base.base.key;
        }
        if (error != ENOENT)
                goto done;

        /*
         * Mark the record as undergoing synchronization.  Our cursor is
         * holding a locked B-Tree node for the insertion which interlocks
         * anyone trying to access this record.
         *
         * XXX There is still a race present related to iterations.  An
         * iteration may process the record, a sync may occur, and then
         * later process the B-Tree element for the same record.
         *
         * We do not try to synchronize a deleted record.
         */
        if (record->flags & HAMMER_RECF_DELETED) {
                error = 0;
                goto done;
        }

        /*
         * Allocate the record and data.  The result buffers will be
         * marked as being modified and further calls to
         * hammer_modify_buffer() will result in unneeded UNDO records.
         *
         * Support zero-fill records.
         */
        if (record->data == NULL)
                alloc_data_len = 0;
        else
                alloc_data_len = record->rec.base.data_len;

        rec = hammer_alloc_record(hmp, &rec_offset,
                                  record->rec.base.base.rec_type,
                                  record->rec_len, &cursor.record_buffer,
                                  &data_offset, alloc_data_len,
                                  &bdata1, NULL, NULL,
                                  NULL, &error);

        if (rec == NULL)
                goto done;

        /*
         * Fill in the remaining fields and insert our B-Tree node.
         */
        rec->base.base = record->rec.base.base;
        if (record->rec_len > sizeof(rec->base)) {
                bcopy(&record->rec.base + 1, &rec->base + 1,
                      record->rec_len - sizeof(rec->base));
        }

        /*
         * Copy the data and deal with zero-fill support.
         */
        if (record->data) {
                rec->base.head.hdr_crc = crc32(record->data, alloc_data_len);
                KKASSERT(alloc_data_len == rec->base.data_len);
                bcopy(record->data, bdata1, alloc_data_len);
        } else {
                rec->base.data_len = record->rec.base.data_len;
        }

        elm.leaf.base = record->rec.base.base;
        elm.leaf.rec_offset = rec_offset;
        elm.leaf.data_offset = data_offset;
        elm.leaf.data_len = rec->base.data_len;
        elm.leaf.data_crc = rec->base.head.hdr_crc;

        error = hammer_btree_insert(&cursor, &elm);

        /*
         * Clean up on success, or fall through on error.
         */
        if (error == 0) {
                record->flags |= HAMMER_RECF_DELETED;
                goto done;
        }

        /*
         * Try to unwind the fifo allocation
         */
        rec->base.head.hdr_type |= HAMMER_HEAD_TYPEF_FREED;
        hammer_unwind_fifo(hmp, rec_offset);
done:
        record->flags &= ~HAMMER_RECF_SYNCING;
        hammer_done_cursor(&cursor);
        if (error == EDEADLK)
                goto retry;
        return(error);
}

/*
 * Add the record to the inode's rec_tree.  The low 32 bits of a directory
 * entry's key is used to deal with hash collisions in the upper 32 bits.
 * A unique 64 bit key is generated in-memory and may be regenerated a
 * second time when the directory record is flushed to the on-disk B-Tree.
 *
 * A referenced record is passed to this function.  This function
 * eats the reference.  If an error occurs the record will be deleted.
 *
 * A copy of the temporary record->data pointer provided by the caller
 * will be made.
 */
static
int
hammer_mem_add(struct hammer_transaction *trans, hammer_record_t record)
{
        int bytes;
        void *data;
                
        /*
         * Make a private copy of record->data
         */
        if (record->data) {
                /*
                 * Try to embed the data in extra space in the record
                 * union, otherwise allocate a copy.
                 */
                bytes = record->rec.base.data_len;
                if (bytes <= (int)sizeof(record->rec) - record->rec_len) {
                        bcopy(record->data,
                              (char *)&record->rec + record->rec_len, bytes);
                        record->data = (void *)((char *)&record->rec +
                                                        record->rec_len);
                } else {
                        ++hammer_count_record_datas;
                        data = kmalloc(bytes, M_HAMMER, M_WAITOK);
                        record->flags |= HAMMER_RECF_ALLOCDATA;
                        bcopy(record->data, data, bytes);
                        record->data = data;
                }
        }

        /*
         * Insert into the RB tree, find an unused iterator if this is
         * a directory entry.
         */
        while (RB_INSERT(hammer_rec_rb_tree, &record->ip->rec_tree, record)) {
                if (record->rec.base.base.rec_type != HAMMER_RECTYPE_DIRENTRY){
                        record->flags |= HAMMER_RECF_DELETED;
                        hammer_rel_mem_record(record);
                        return (EEXIST);
                }
                if (++trans->hmp->namekey_iterator == 0)
                        ++trans->hmp->namekey_iterator;
                record->rec.base.base.key &= ~(0xFFFFFFFFLL);
                record->rec.base.base.key |= trans->hmp->namekey_iterator;
        }
        record->flags |= HAMMER_RECF_ONRBTREE;
        hammer_modify_inode(trans, record->ip, HAMMER_INODE_XDIRTY);
        hammer_rel_mem_record(record);
        return(0);
}

/************************************************************************
 *                   HAMMER INODE MERGED-RECORD FUNCTIONS               *
 ************************************************************************
 *
 * These functions augment the B-Tree scanning functions in hammer_btree.c
 * by merging in-memory records with on-disk records.
 */

/*
 * Locate a particular record either in-memory or on-disk.
 *
 * NOTE: This is basically a standalone routine, hammer_ip_next() may
 * NOT be called to iterate results.
 */
int
hammer_ip_lookup(hammer_cursor_t cursor, struct hammer_inode *ip)
{
        int error;

        /*
         * If the element is in-memory return it without searching the
         * on-disk B-Tree
         */
        error = hammer_mem_lookup(cursor, ip);
        if (error == 0) {
                cursor->record = &cursor->iprec->rec;
                return(error);
        }
        if (error != ENOENT)
                return(error);

        /*
         * If the inode has on-disk components search the on-disk B-Tree.
         */
        if ((ip->flags & (HAMMER_INODE_ONDISK|HAMMER_INODE_DONDISK)) == 0)
                return(error);
        error = hammer_btree_lookup(cursor);
        if (error == 0)
                error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_RECORD);
        return(error);
}

/*
 * Locate the first record within the cursor's key_beg/key_end range,
 * restricted to a particular inode.  0 is returned on success, ENOENT
 * if no records matched the requested range, or some other error.
 *
 * When 0 is returned hammer_ip_next() may be used to iterate additional
 * records within the requested range.
 *
 * This function can return EDEADLK, requiring the caller to terminate
 * the cursor and try again.
 */
int
hammer_ip_first(hammer_cursor_t cursor, struct hammer_inode *ip)
{
        int error;

        /*
         * Clean up fields and setup for merged scan
         */
        cursor->flags &= ~HAMMER_CURSOR_DELBTREE;
        cursor->flags |= HAMMER_CURSOR_ATEDISK | HAMMER_CURSOR_ATEMEM;
        cursor->flags |= HAMMER_CURSOR_DISKEOF | HAMMER_CURSOR_MEMEOF;
        if (cursor->iprec) {
                hammer_rel_mem_record(cursor->iprec);
                cursor->iprec = NULL;
        }

        /*
         * Search the on-disk B-Tree.  hammer_btree_lookup() only does an
         * exact lookup so if we get ENOENT we have to call the iterate
         * function to validate the first record after the begin key.
         *
         * The ATEDISK flag is used by hammer_btree_iterate to determine
         * whether it must index forwards or not.  It is also used here
         * to select the next record from in-memory or on-disk.
         *
         * EDEADLK can only occur if the lookup hit an empty internal
         * element and couldn't delete it.  Since this could only occur
         * in-range, we can just iterate from the failure point.
         */
        if (ip->flags & (HAMMER_INODE_ONDISK|HAMMER_INODE_DONDISK)) {
                error = hammer_btree_lookup(cursor);
                if (error == ENOENT || error == EDEADLK) {
                        cursor->flags &= ~HAMMER_CURSOR_ATEDISK;
                        error = hammer_btree_iterate(cursor);
                }
                if (error && error != ENOENT) 
                        return(error);
                if (error == 0) {
                        cursor->flags &= ~HAMMER_CURSOR_DISKEOF;
                        cursor->flags &= ~HAMMER_CURSOR_ATEDISK;
                } else {
                        cursor->flags |= HAMMER_CURSOR_ATEDISK;
                }
        }

        /*
         * Search the in-memory record list (Red-Black tree).  Unlike the
         * B-Tree search, mem_first checks for records in the range.
         */
        error = hammer_mem_first(cursor, ip);
        if (error && error != ENOENT)
                return(error);
        if (error == 0) {
                cursor->flags &= ~HAMMER_CURSOR_MEMEOF;
                cursor->flags &= ~HAMMER_CURSOR_ATEMEM;
        }

        /*
         * This will return the first matching record.
         */
        return(hammer_ip_next(cursor));
}

/*
 * Retrieve the next record in a merged iteration within the bounds of the
 * cursor.  This call may be made multiple times after the cursor has been
 * initially searched with hammer_ip_first().
 *
 * 0 is returned on success, ENOENT if no further records match the
 * requested range, or some other error code is returned.
 */
int
hammer_ip_next(hammer_cursor_t cursor)
{
        hammer_btree_elm_t elm;
        hammer_record_t rec;
        int error;
        int r;

        /*
         * Load the current on-disk and in-memory record.  If we ate any
         * records we have to get the next one. 
         *
         * If we deleted the last on-disk record we had scanned ATEDISK will
         * be clear and DELBTREE will be set, forcing a call to iterate. The
         * fact that ATEDISK is clear causes iterate to re-test the 'current'
         * element.  If ATEDISK is set, iterate will skip the 'current'
         * element.
         *
         * Get the next on-disk record
         */
        if (cursor->flags & (HAMMER_CURSOR_ATEDISK|HAMMER_CURSOR_DELBTREE)) {
                if ((cursor->flags & HAMMER_CURSOR_DISKEOF) == 0) {
                        error = hammer_btree_iterate(cursor);
                        cursor->flags &= ~HAMMER_CURSOR_DELBTREE;
                        if (error == 0)
                                cursor->flags &= ~HAMMER_CURSOR_ATEDISK;
                        else
                                cursor->flags |= HAMMER_CURSOR_DISKEOF |
                                                 HAMMER_CURSOR_ATEDISK;
                }
        }

        /*
         * Get the next in-memory record.  The record can be ripped out
         * of the RB tree so we maintain a scan_info structure to track
         * the next node.
         *
         * hammer_rec_scan_cmp:  Is the record still in our general range,
         *                       (non-inclusive of snapshot exclusions)?
         * hammer_rec_scan_callback: Is the record in our snapshot?
         */
        if (cursor->flags & HAMMER_CURSOR_ATEMEM) {
                if ((cursor->flags & HAMMER_CURSOR_MEMEOF) == 0) {
                        if (cursor->iprec) {
                                hammer_rel_mem_record(cursor->iprec);
                                cursor->iprec = NULL;
                        }
                        rec = cursor->scan.node;        /* next node */
                        while (rec) {
                                if (hammer_rec_scan_cmp(rec, cursor) != 0)
                                        break;
                                if (hammer_rec_scan_callback(rec, cursor) != 0)
                                        break;
                                rec = hammer_rec_rb_tree_RB_NEXT(rec);
                        }
                        if (cursor->iprec) {
                                KKASSERT(cursor->iprec == rec);
                                cursor->flags &= ~HAMMER_CURSOR_ATEMEM;
                                cursor->scan.node =
                                        hammer_rec_rb_tree_RB_NEXT(rec);
                        } else {
                                cursor->flags |= HAMMER_CURSOR_MEMEOF;
                        }
                }
        }

        /*
         * Extract either the disk or memory record depending on their
         * relative position.
         */
        error = 0;
        switch(cursor->flags & (HAMMER_CURSOR_ATEDISK | HAMMER_CURSOR_ATEMEM)) {
        case 0:
                /*
                 * Both entries valid
                 */
                elm = &cursor->node->ondisk->elms[cursor->index];
                r = hammer_btree_cmp(&elm->base, &cursor->iprec->rec.base.base);
                if (r < 0) {
                        error = hammer_btree_extract(cursor,
                                                     HAMMER_CURSOR_GET_RECORD);
                        cursor->flags |= HAMMER_CURSOR_ATEDISK;
                        break;
                }
                /* fall through to the memory entry */
        case HAMMER_CURSOR_ATEDISK:
                /*
                 * Only the memory entry is valid
                 */
                cursor->record = &cursor->iprec->rec;
                cursor->flags |= HAMMER_CURSOR_ATEMEM;
                break;
        case HAMMER_CURSOR_ATEMEM:
                /*
                 * Only the disk entry is valid
                 */
                error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_RECORD);
                cursor->flags |= HAMMER_CURSOR_ATEDISK;
                break;
        default:
                /*
                 * Neither entry is valid
                 *
                 * XXX error not set properly
                 */
                cursor->record = NULL;
                error = ENOENT;
                break;
        }
        return(error);
}

/*
 * Resolve the cursor->data1/2 pointer for the current cursor position in
 * a merged iteration.
 */
int
hammer_ip_resolve_data(hammer_cursor_t cursor)
{
        int error;

        if (cursor->iprec && cursor->record == &cursor->iprec->rec) {
                cursor->data1 = cursor->iprec->data;
                cursor->data2 = NULL;
                cursor->data_split = cursor->iprec->rec.base.data_len;
                error = 0;
        } else {
                error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA);
        }
        return(error);
}

/*
 * Delete all records within the specified range for inode ip.
 *
 * NOTE: An unaligned range will cause new records to be added to cover
 * the edge cases. (XXX not implemented yet).
 *
 * NOTE: ran_end is inclusive (e.g. 0,1023 instead of 0,1024).
 *
 * NOTE: Record keys for regular file data have to be special-cased since
 * they indicate the end of the range (key = base + bytes).
 */
int
hammer_ip_delete_range(hammer_transaction_t trans, hammer_inode_t ip,
                       int64_t ran_beg, int64_t ran_end)
{
        struct hammer_cursor cursor;
        hammer_record_ondisk_t rec;
        hammer_base_elm_t base;
        int error;
        int64_t off;

retry:
        hammer_init_cursor_hmp(&cursor, &ip->cache[0], ip->hmp);

        cursor.key_beg.obj_id = ip->obj_id;
        cursor.key_beg.create_tid = 0;
        cursor.key_beg.delete_tid = 0;
        cursor.key_beg.obj_type = 0;
        cursor.asof = ip->obj_asof;
        cursor.flags |= HAMMER_CURSOR_ASOF;

        cursor.key_end = cursor.key_beg;
        if (ip->ino_rec.base.base.obj_type == HAMMER_OBJTYPE_DBFILE) {
                cursor.key_beg.key = ran_beg;
                cursor.key_beg.rec_type = HAMMER_RECTYPE_DB;
                cursor.key_end.rec_type = HAMMER_RECTYPE_DB;
                cursor.key_end.key = ran_end;
        } else {
                /*
                 * The key in the B-Tree is (base+bytes), so the first possible
                 * matching key is ran_beg + 1.
                 */
                int64_t tmp64;

                cursor.key_beg.key = ran_beg + 1;
                cursor.key_beg.rec_type = HAMMER_RECTYPE_DATA;
                cursor.key_end.rec_type = HAMMER_RECTYPE_DATA;

                tmp64 = ran_end + MAXPHYS + 1;  /* work around GCC-4 bug */
                if (tmp64 < ran_end)
                        cursor.key_end.key = 0x7FFFFFFFFFFFFFFFLL;
                else
                        cursor.key_end.key = ran_end + MAXPHYS + 1;
        }
        cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;

        error = hammer_ip_first(&cursor, ip);

        /*
         * Iterate through matching records and mark them as deleted.
         */
        while (error == 0) {
                rec = cursor.record;
                base = &rec->base.base;

                KKASSERT(base->delete_tid == 0);

                /*
                 * There may be overlap cases for regular file data.  Also
                 * remember the key for a regular file record is the offset
                 * of the last byte of the record (base + len - 1), NOT the
                 * base offset.
                 */
#if 0
                kprintf("delete_range rec_type %02x\n", base->rec_type);
#endif
                if (base->rec_type == HAMMER_RECTYPE_DATA) {
#if 0
                        kprintf("delete_range loop key %016llx\n",
                                base->key - rec->base.data_len);
#endif
                        off = base->key - rec->base.data_len;
                        /*
                         * Check the left edge case.  We currently do not
                         * split existing records.
                         */
                        if (off < ran_beg) {
                                panic("hammer left edge case %016llx %d\n",
                                        base->key, rec->base.data_len);
                        }

                        /*
                         * Check the right edge case.  Note that the
                         * record can be completely out of bounds, which
                         * terminates the search.
                         *
                         * base->key is exclusive of the right edge while
                         * ran_end is inclusive of the right edge.  The
                         * (key - data_len) left boundary is inclusive.
                         *
                         * XXX theory-check this test at some point, are
                         * we missing a + 1 somewhere?  Note that ran_end
                         * could overflow.
                         */
                        if (base->key - 1 > ran_end) {
                                if (base->key - rec->base.data_len > ran_end)
                                        break;
                                panic("hammer right edge case\n");
                        }
                }

                /*
                 * Mark the record and B-Tree entry as deleted.  This will
                 * also physically delete the B-Tree entry, record, and
                 * data if the retention policy dictates.  The function
                 * will set HAMMER_CURSOR_DELBTREE which hammer_ip_next()
                 * uses to perform a fixup.
                 */
                error = hammer_ip_delete_record(&cursor, trans->tid);
                if (error)
                        break;
                error = hammer_ip_next(&cursor);
        }
        hammer_done_cursor(&cursor);
        if (error == EDEADLK)
                goto retry;
        if (error == ENOENT)
                error = 0;
        return(error);
}

/*
 * Delete all records associated with an inode except the inode record
 * itself.
 */
int
hammer_ip_delete_range_all(hammer_transaction_t trans, hammer_inode_t ip)
{
        struct hammer_cursor cursor;
        hammer_record_ondisk_t rec;
        hammer_base_elm_t base;
        int error;

retry:
        hammer_init_cursor_hmp(&cursor, &ip->cache[0], ip->hmp);

        cursor.key_beg.obj_id = ip->obj_id;
        cursor.key_beg.create_tid = 0;
        cursor.key_beg.delete_tid = 0;
        cursor.key_beg.obj_type = 0;
        cursor.key_beg.rec_type = HAMMER_RECTYPE_INODE + 1;
        cursor.key_beg.key = HAMMER_MIN_KEY;

        cursor.key_end = cursor.key_beg;
        cursor.key_end.rec_type = 0xFFFF;
        cursor.key_end.key = HAMMER_MAX_KEY;

        cursor.asof = ip->obj_asof;
        cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE | HAMMER_CURSOR_ASOF;

        error = hammer_ip_first(&cursor, ip);

        /*
         * Iterate through matching records and mark them as deleted.
         */
        while (error == 0) {
                rec = cursor.record;
                base = &rec->base.base;

                KKASSERT(base->delete_tid == 0);

                /*
                 * Mark the record and B-Tree entry as deleted.  This will
                 * also physically delete the B-Tree entry, record, and
                 * data if the retention policy dictates.  The function
                 * will set HAMMER_CURSOR_DELBTREE which hammer_ip_next()
                 * uses to perform a fixup.
                 */
                error = hammer_ip_delete_record(&cursor, trans->tid);
                if (error)
                        break;
                error = hammer_ip_next(&cursor);
        }
        hammer_done_cursor(&cursor);
        if (error == EDEADLK)
                goto retry;
        if (error == ENOENT)
                error = 0;
        return(error);
}

/*
 * Delete the record at the current cursor.  On success the cursor will
 * be positioned appropriately for an iteration but may no longer be at
 * a leaf node.
 *
 * NOTE: This can return EDEADLK, requiring the caller to terminate the
 * cursor and retry.
 */
int
hammer_ip_delete_record(hammer_cursor_t cursor, hammer_tid_t tid)
{
        hammer_btree_elm_t elm;
        hammer_mount_t hmp;
        int error;
        int dodelete;

        /*
         * In-memory (unsynchronized) records can simply be freed.
         */
        if (cursor->record == &cursor->iprec->rec) {
                cursor->iprec->flags |= HAMMER_RECF_DELETED;
                return(0);
        }

        /*
         * On-disk records are marked as deleted by updating their delete_tid.
         * This does not effect their position in the B-Tree (which is based
         * on their create_tid).
         */
        error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_RECORD);
        elm = NULL;
        hmp = cursor->node->volume->hmp;

        dodelete = 0;
        if (error == 0) {
                error = hammer_cursor_upgrade(cursor);
                if (error == 0) {
                        hammer_modify_node(cursor->node);
                        elm = &cursor->node->ondisk->elms[cursor->index];
                        elm->leaf.base.delete_tid = tid;
                        hammer_modify_buffer(cursor->record_buffer, &cursor->record->base.base.delete_tid, sizeof(hammer_tid_t));
                        cursor->record->base.base.delete_tid = tid;
                }
        }

        /*
         * If we were mounted with the nohistory option, we physically
         * delete the record.
         */
        if (hmp->hflags & HMNT_NOHISTORY)
                dodelete = 1;

        if (error == 0 && dodelete) {
                error = hammer_delete_at_cursor(cursor, NULL);
                if (error) {
                        panic("hammer_ip_delete_record: unable to physically delete the record!\n");
                        error = 0;
                }
        }
        return(error);
}

int
hammer_delete_at_cursor(hammer_cursor_t cursor, int64_t *stat_bytes)
{
        hammer_btree_elm_t elm;
        hammer_off_t rec_offset;
        hammer_off_t data_offset;
        int32_t data_len;
        u_int8_t rec_type;
        int error;

        elm = &cursor->node->ondisk->elms[cursor->index];
        KKASSERT(elm->base.btype == HAMMER_BTREE_TYPE_RECORD);

        rec_offset = elm->leaf.rec_offset;
        data_offset = elm->leaf.data_offset;
        data_len = elm->leaf.data_len;
        rec_type = elm->leaf.base.rec_type;

        error = hammer_btree_delete(cursor);
        if (error == 0) {
                /*
                 * This forces a fixup for the iteration because
                 * the cursor is now either sitting at the 'next'
                 * element or sitting at the end of a leaf.
                 */
                if ((cursor->flags & HAMMER_CURSOR_DISKEOF) == 0) {
                        cursor->flags |= HAMMER_CURSOR_DELBTREE;
                        cursor->flags &= ~HAMMER_CURSOR_ATEDISK;
                }
                hammer_free_fifo(cursor->node->volume->hmp, rec_offset);
        }
#if 0
        kprintf("hammer_delete_at_cursor: %d:%d:%08x %08x/%d "
                "(%d remain in cluster)\n",
                cluster->volume->vol_no, cluster->clu_no,
                rec_offset, data_offset, data_len,
                cluster->ondisk->stat_records);
#endif
        return (error);
}

/*
 * Determine whether a directory is empty or not.  Returns 0 if the directory
 * is empty, ENOTEMPTY if it isn't, plus other possible errors.
 */
int
hammer_ip_check_directory_empty(hammer_transaction_t trans, hammer_inode_t ip)
{
        struct hammer_cursor cursor;
        int error;

        hammer_init_cursor_hmp(&cursor, &ip->cache[0], ip->hmp);

        cursor.key_beg.obj_id = ip->obj_id;
        cursor.key_beg.create_tid = 0;
        cursor.key_beg.delete_tid = 0;
        cursor.key_beg.obj_type = 0;
        cursor.key_beg.rec_type = HAMMER_RECTYPE_INODE + 1;
        cursor.key_beg.key = HAMMER_MIN_KEY;

        cursor.key_end = cursor.key_beg;
        cursor.key_end.rec_type = 0xFFFF;
        cursor.key_end.key = HAMMER_MAX_KEY;

        cursor.asof = ip->obj_asof;
        cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE | HAMMER_CURSOR_ASOF;

        error = hammer_ip_first(&cursor, ip);
        if (error == ENOENT)
                error = 0;
        else if (error == 0)
                error = ENOTEMPTY;
        hammer_done_cursor(&cursor);
        return(error);
}