HAMMER 40B/Many: Inode/link-count sequencer cleanup pass.

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

/*
 * Copyright (c) 2007-2008 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 1.49 2008/05/02 06:51:57 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);

        /*
         * Never match against an item deleted by the front-end.
         */
        if (rec1->flags & HAMMER_RECF_DELETED_FE)
                return(1);
        if (rec2->flags & HAMMER_RECF_DELETED_FE)
                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);
}

/*
 * This compare function is used when simply looking up key_beg.
 */
static
int
hammer_rec_find_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);
        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)
{
        hammer_record_t record;

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

void
hammer_wait_mem_record(hammer_record_t record)
{
        while (record->flush_state == HAMMER_FST_FLUSH) {
                record->flags |= HAMMER_RECF_WANTED;
                tsleep(record, 0, "hmrrc2", 0);
        }
}

/*
 * Called from the backend, hammer_inode.c, after a record has been
 * flushed to disk.  The record has been exclusively locked by the
 * caller and interlocked with BE.
 *
 * We clean up the state, unlock, and release the record (the record
 * was referenced by the fact that it was in the HAMMER_FST_FLUSH state).
 */
void
hammer_flush_record_done(hammer_record_t record, int error)
{
        hammer_inode_t target_ip;
        int cleanup = 0;

        KKASSERT(record->flush_state == HAMMER_FST_FLUSH);
        KKASSERT(record->flags & HAMMER_RECF_INTERLOCK_BE);

        if (error) {
                /*
                 * An error occured, the backend was unable to sync the
                 * record to its media.  Leave the record intact.
                 */
                Debugger("flush_record_done error");
        } else if (record->flags & HAMMER_RECF_CONVERT_DELETE) {
                /*
                 * deleted-record to delete-on-disk conversion, occurs when
                 * we sync a record to disk which is marked deleted by the
                 * frontend, but not deleted from the point of view of the
                 * backend.
                 */
                if (record->flags & HAMMER_RECF_DELETED_BE) {
                        record->flags |= HAMMER_RECF_DELETED_FE;
                        cleanup = 1;
                } else {
                        KKASSERT(record->type == HAMMER_MEM_RECORD_DEL);
                }
        } else {
                /*
                 * Normal completion, record has been disposed of (by
                 * having been synchronized to the media).
                 */
                record->flags |= HAMMER_RECF_DELETED_FE;
                record->flags |= HAMMER_RECF_DELETED_BE;
                cleanup = 1;
        }
        if (cleanup) {
                if ((target_ip = record->target_ip) != NULL) {
                        TAILQ_REMOVE(&target_ip->target_list, record,
                                     target_entry);
                        record->target_ip = NULL;
                        hammer_test_inode(target_ip);
                }
                record->flush_state = HAMMER_FST_IDLE;
        } else {
                if (record->target_ip)
                        record->flush_state = HAMMER_FST_SETUP;
                else
                        record->flush_state = HAMMER_FST_IDLE;
        }

        record->flags &= ~HAMMER_RECF_INTERLOCK_BE;
        record->flags &= ~HAMMER_RECF_CONVERT_DELETE;
        if (record->flags & HAMMER_RECF_WANTED) {
                record->flags &= ~HAMMER_RECF_WANTED;
                wakeup(record);
        }
        hammer_rel_mem_record(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_inode_t ip, target_ip;

        hammer_unref(&record->lock);

        if (record->flags & HAMMER_RECF_DELETED_FE) {
                if (record->lock.refs == 0) {
                        KKASSERT(record->flush_state != HAMMER_FST_FLUSH);

                        ip = record->ip;
                        if ((target_ip = record->target_ip) != NULL) {
                                TAILQ_REMOVE(&target_ip->target_list,
                                             record, target_entry);
                                record->target_ip = NULL;
                                hammer_test_inode(target_ip);
                        }

                        if (record->flags & HAMMER_RECF_ONRBTREE) {
                                RB_REMOVE(hammer_rec_rb_tree,
                                          &record->ip->rec_tree,
                                          record);
                                record->flags &= ~HAMMER_RECF_ONRBTREE;
                        }
                        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;
                }
        }
}

/*
 * Record visibility depends on whether the record is being accessed by
 * the backend or the frontend.
 *
 * Return non-zero if the record is visible, zero if it isn't or if it is
 * deleted.
 */
static __inline
int
hammer_ip_iterate_mem_good(hammer_cursor_t cursor, hammer_record_t record)
{
        if (cursor->flags & HAMMER_CURSOR_BACKEND) {
                if (record->flags & HAMMER_RECF_DELETED_BE)
                        return(0);
                if ((record->flags & HAMMER_RECF_INTERLOCK_BE) == 0)
                        return(0);
        } else {
                if (record->flags & HAMMER_RECF_DELETED_FE)
                        return(0);
        }
        return(1);
}

/*
 * This callback is used as part of the RB_SCAN function for in-memory
 * records.  We terminate it (return -1) as soon as we get a match.
 *
 * This routine is used by frontend code.
 *
 * The primary compare code does not account for ASOF lookups.  This
 * code handles that case as well as a few others.
 */
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 (hammer_ip_iterate_mem_good(cursor, rec) == 0)
                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);
                }
        }

        /*
         * If the record is queued to the flusher we have to block until
         * it isn't.  Otherwise we may see duplication between our memory
         * cache and the media.
         */
        hammer_ref(&rec->lock);

#warning "This deadlocks"
#if 0
        if (rec->flush_state == HAMMER_FST_FLUSH)
                hammer_wait_mem_record(rec);
#endif

        /*
         * The record may have been deleted while we were blocked.
         */
        if (hammer_ip_iterate_mem_good(cursor, rec) == 0) {
                hammer_rel_mem_record(rec);
                return(0);
        }

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


/*
 * 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) {
                KKASSERT(cursor->ip->cursor_ip_refs > 0);
                --cursor->ip->cursor_ip_refs;
#if 0
                hammer_rec_rb_tree_scan_info_done(&cursor->scan,
                                                  &cursor->ip->rec_tree);
#endif
        }
        cursor->ip = ip;
#if 0
        hammer_rec_rb_tree_scan_info_link(&cursor->scan, &ip->rec_tree);
#endif
        ++ip->cursor_ip_refs;

#if 0
        cursor->scan.node = NULL;
#endif
        hammer_rec_rb_tree_RB_SCAN(&ip->rec_tree, hammer_rec_find_cmp,
                                   hammer_rec_scan_callback, cursor);

        if (cursor->iprec == NULL)
                error = ENOENT;
        else
                error = 0;
        return(error);
}

/*
 * hammer_mem_first() - locate the first in-memory record matching the
 * cursor within the bounds of the key range.
 */
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) {
                KKASSERT(cursor->ip->cursor_ip_refs > 0);
                --cursor->ip->cursor_ip_refs;
#if 0
                hammer_rec_rb_tree_scan_info_done(&cursor->scan,
                                                  &cursor->ip->rec_tree);
#endif
        }
        cursor->ip = ip;
#if 0
        hammer_rec_rb_tree_scan_info_link(&cursor->scan, &ip->rec_tree);
#endif
        ++ip->cursor_ip_refs;

#if 0
        cursor->scan.node = NULL;
#endif
        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) {
#if 0
                cursor->scan.node = hammer_rec_rb_tree_RB_NEXT(cursor->iprec);
#endif
                return(0);
        }
        return(ENOENT);
}

void
hammer_mem_done(hammer_cursor_t cursor)
{
        if (cursor->ip) {
                KKASSERT(cursor->ip->cursor_ip_refs > 0);
                --cursor->ip->cursor_ip_refs;
#if 0
                hammer_rec_rb_tree_scan_info_done(&cursor->scan,
                                                  &cursor->ip->rec_tree);
#endif
                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);

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

        record->type = HAMMER_MEM_RECORD_ADD;
        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.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);

        /*
         * The target inode and the directory entry are bound together.
         */
        record->target_ip = ip;
        record->flush_state = HAMMER_FST_SETUP;
        TAILQ_INSERT_TAIL(&ip->target_list, record, target_entry);

        /*
         * The inode now has a dependancy and must be taken out of the idle
         * state.  An inode not in an idle state is given an extra reference.
         */
        if (ip->flush_state == HAMMER_FST_IDLE) {
                hammer_ref(&ip->lock);
                ip->flush_state = HAMMER_FST_SETUP;
        }

        /* 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.
 *
 * The related inode should be share-locked by the caller.  The caller is
 * on the frontend.
 *
 * This function can return EDEADLK requiring the caller to terminate
 * the cursor, any locks, wait on the returned record, and retry.
 */
int
hammer_ip_del_directory(struct hammer_transaction *trans,
                     hammer_cursor_t cursor, struct hammer_inode *dip,
                     struct hammer_inode *ip)
{
        hammer_record_t record;
        int error;

        if (cursor->record == &cursor->iprec->rec) {
                /*
                 * In-memory (unsynchronized) records can simply be freed.
                 * Even though the HAMMER_RECF_DELETED_FE flag is ignored
                 * by the backend, we must still avoid races against the
                 * backend potentially syncing the record to the media. 
                 *
                 * We cannot call hammer_ip_delete_record(), that routine may
                 * only be called from the backend.
                 */
                record = cursor->iprec;
                if (record->flags & HAMMER_RECF_INTERLOCK_BE) {
                        KKASSERT(cursor->deadlk_rec == NULL);
                        hammer_ref(&record->lock);
                        cursor->deadlk_rec = record;
                        error = EDEADLK;
                } else {
                        KKASSERT(record->type == HAMMER_MEM_RECORD_ADD);
                        record->flags |= HAMMER_RECF_DELETED_FE;
                        error = 0;
                }
        } else {
                /*
                 * If the record is on-disk we have to queue the deletion by
                 * the record's key.  This also causes lookups to skip the
                 * record.
                 */
                record = hammer_alloc_mem_record(dip);
                record->type = HAMMER_MEM_RECORD_DEL;
                record->rec.entry.base.base = cursor->record->base.base;
                hammer_modify_inode(trans, ip, HAMMER_INODE_RDIRTY);

                record->target_ip = ip;
                record->flush_state = HAMMER_FST_SETUP;
                TAILQ_INSERT_TAIL(&ip->target_list, record, target_entry);

                /*
                 * The inode now has a dependancy and must be taken out of
                 * the idle state.  An inode not in an idle state is given
                 * an extra reference.
                 */
                if (ip->flush_state == HAMMER_FST_IDLE) {
                        hammer_ref(&ip->lock);
                        ip->flush_state = HAMMER_FST_SETUP;
                }

                error = hammer_mem_add(trans, record);
        }

        /*
         * 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.
         *
         * XXX we can't sync the inode here because the encompassing
         * transaction might be a rename and might update the inode
         * again with a new link.  That would force the delete_tid to be
         * the same as the create_tid and cause a panic.
         */
        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);
                }

        }
        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:
 *
 * The related inode should be share-locked by the caller.  The caller is
 * on the frontend.
 *
 * 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.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).
 *
 * The file offset must be HAMMER_BUFSIZE aligned but the data length
 * can be truncated.  The record (currently) always represents a BUFSIZE
 * swath of space whether the data is truncated or not.
 */
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;
        void *bdata;
        int error;

        KKASSERT((offset & HAMMER_BUFMASK) == 0);
        KKASSERT(trans->type == HAMMER_TRANS_FLS);
retry:
        error = hammer_init_cursor(trans, &cursor, &ip->cache[0]);
        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;
        cursor.flags |= HAMMER_CURSOR_BACKEND;

        /*
         * 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) tid %016llx\n",
                        offset, bytes, trans->tid);
                hammer_print_btree_elm(&cursor.node->ondisk->elms[cursor.index],
                                       HAMMER_BTREE_TYPE_LEAF, cursor.index);
                panic("Duplicate data");
                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(trans, &rec_offset, HAMMER_RECTYPE_DATA,
                                  &cursor.record_buffer,
                                  bytes, &bdata,
                                  &cursor.data_buffer, &error);
        if (rec == NULL)
                goto done;
        if (hammer_debug_general & 0x1000)
                kprintf("OOB RECOR2 DATA REC %016llx DATA %016llx LEN=%d\n", rec_offset, rec->base.data_off, rec->base.data_len);

        /*
         * 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.
         */
        hammer_modify_buffer(trans, cursor.record_buffer, NULL, 0);
        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.data_crc = crc32(data, bytes);
        hammer_modify_buffer_done(cursor.record_buffer);
        KKASSERT(rec->base.data_len == bytes);

        hammer_modify_buffer(trans, cursor.data_buffer, NULL, 0);
        bcopy(data, bdata, bytes);
        hammer_modify_buffer_done(cursor.data_buffer);

        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.data_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;

        hammer_blockmap_free(trans, rec_offset, HAMMER_RECORD_SIZE);
done:
        hammer_done_cursor(&cursor);
        if (error == EDEADLK)
                goto retry;
        return(error);
}

/*
 * Sync an in-memory record to the disk.  This is called by the backend.
 * This code is responsible for actually writing a record out to the disk.
 *
 * This routine can only be called by the backend and the record
 * must have been interlocked with BE.  It will remain interlocked on
 * return.  The caller is responsible for the record's disposition.
 */
int
hammer_ip_sync_record(hammer_transaction_t trans, hammer_record_t record)
{
        struct hammer_cursor cursor;
        hammer_record_ondisk_t rec;
        union hammer_btree_elm elm;
        hammer_off_t rec_offset;
        void *bdata;
        int error;

        KKASSERT(record->flush_state == HAMMER_FST_FLUSH);
        KKASSERT(record->flags & HAMMER_RECF_INTERLOCK_BE);

retry:
        /*
         * Get a cursor, we will either be inserting or deleting.
         */
        error = hammer_init_cursor(trans, &cursor, &record->ip->cache[0]);
        if (error)
                return(error);
        cursor.key_beg = record->rec.base.base;
        cursor.flags |= HAMMER_CURSOR_BACKEND;

        /*
         * If we are deleting an exact match must be found on-disk.
         */
        if (record->type == HAMMER_MEM_RECORD_DEL) {
                error = hammer_btree_lookup(&cursor);
                if (error == 0)
                        error = hammer_ip_delete_record(&cursor, trans->tid);
                goto done;
        }

        /*
         * We are inserting.
         *
         * 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.
         */
        cursor.flags |= HAMMER_CURSOR_INSERT;

        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 (++trans->hmp->namekey_iterator == 0)
                        ++trans->hmp->namekey_iterator;
                record->rec.base.base.key &= ~(0xFFFFFFFFLL);
                record->rec.base.base.key |= trans->hmp->namekey_iterator;
                cursor.key_beg.key = record->rec.base.base.key;
        }
        if (error != ENOENT)
                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 (data == NULL and data_len != 0)
         */
        if (record->data == NULL) {
                rec = hammer_alloc_record(trans, &rec_offset,
                                          record->rec.base.base.rec_type,
                                          &cursor.record_buffer,
                                          0, &bdata,
                                          NULL, &error);
                if (hammer_debug_general & 0x1000)
                        kprintf("NULL RECORD DATA\n");
        } else if (record->flags & HAMMER_RECF_INBAND) {
                rec = hammer_alloc_record(trans, &rec_offset,
                                          record->rec.base.base.rec_type,
                                          &cursor.record_buffer,
                                          record->rec.base.data_len, &bdata,
                                          NULL, &error);
                if (hammer_debug_general & 0x1000)
                        kprintf("INBAND RECORD DATA %016llx DATA %016llx LEN=%d\n", rec_offset, rec->base.data_off, record->rec.base.data_len);
        } else {
                rec = hammer_alloc_record(trans, &rec_offset,
                                          record->rec.base.base.rec_type,
                                          &cursor.record_buffer,
                                          record->rec.base.data_len, &bdata,
                                          &cursor.data_buffer, &error);
                if (hammer_debug_general & 0x1000)
                        kprintf("OOB RECORD DATA REC %016llx DATA %016llx LEN=%d\n", rec_offset, rec->base.data_off, record->rec.base.data_len);
        }

        if (rec == NULL)
                goto done;

        /*
         * Fill in the remaining fields and insert our B-Tree node.
         */
        hammer_modify_buffer(trans, cursor.record_buffer, NULL, 0);
        rec->base.base = record->rec.base.base;
        bcopy(&record->rec.base + 1, &rec->base + 1,
              HAMMER_RECORD_SIZE - sizeof(record->rec.base));

        /*
         * Copy the data and deal with zero-fill support.
         */
        if (record->data && (record->flags & HAMMER_RECF_INBAND)) {
                rec->base.data_crc = crc32(record->data, rec->base.data_len);
                bcopy(record->data, bdata, rec->base.data_len);
        } else if (record->data) {
                rec->base.data_crc = crc32(record->data, rec->base.data_len);
                hammer_modify_buffer(trans, cursor.data_buffer, NULL, 0);
                bcopy(record->data, bdata, rec->base.data_len);
                hammer_modify_buffer_done(cursor.data_buffer);
        } else {
                rec->base.data_len = record->rec.base.data_len;
        }
        hammer_modify_buffer_done(cursor.record_buffer);

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

        error = hammer_btree_insert(&cursor, &elm);

        /*
         * This occurs when the frontend creates a record and queues it to
         * the backend, then tries to delete the record.  The backend must
         * still sync the record to the media as if it were not deleted,
         * but must interlock with the frontend to ensure that the 
         * synchronized record is not visible to the frontend, which means
         * converting it from an ADD record to a DEL record.
         *
         * The DEL record then masks the record synced to disk until another
         * round can delete it for real.
         */
        if (error == 0 && (record->flags & HAMMER_RECF_CONVERT_DELETE)) {
                KKASSERT(record->type == HAMMER_MEM_RECORD_ADD);
                record->flags &= ~HAMMER_RECF_DELETED_FE;
                record->type = HAMMER_MEM_RECORD_DEL;
                if (record->flush_state == HAMMER_FST_SETUP) {
                        hammer_test_inode(record->ip);
                        hammer_test_inode(record->target_ip);
                }
        }

        /*
         * If the error occured unwind the operation.
         */
        if (error)
                hammer_blockmap_free(trans, rec_offset, HAMMER_RECORD_SIZE);

done:
        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)
{
        void *data;
        int bytes;
        int reclen;
                
        /*
         * 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;
                switch(record->rec.base.base.rec_type) {
                case HAMMER_RECTYPE_DIRENTRY:
                        reclen = offsetof(struct hammer_entry_record, name[0]);
                        break;
                case HAMMER_RECTYPE_DATA:
                        reclen = offsetof(struct hammer_data_record, data[0]);
                        break;
                default:
                        reclen = sizeof(record->rec);
                        break;
                }
                if (reclen + bytes <= HAMMER_RECORD_SIZE) {
                        bcopy(record->data, (char *)&record->rec + reclen,
                              bytes);
                        record->data = (void *)((char *)&record->rec + reclen);
                        record->flags |= HAMMER_RECF_INBAND;
                } 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_FE;
                        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;
                        if (hammer_debug_general & 0x2000)
                                kprintf("error %d node %p %016llx index %d\n", error, cursor->node, cursor->node->node_offset, cursor->index);
                        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;
                if (hammer_ip_iterate_mem_good(cursor, cursor->iprec) == 0)
                        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, save;
        int error;
        int r;

next_btree:
        /*
         * 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;
                }
        }

next_memory:
        /*
         * 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) {
                        save = cursor->iprec;
                        cursor->iprec = NULL;
                        rec = save ? hammer_rec_rb_tree_RB_NEXT(save) : NULL;
                        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 (save)
                                hammer_rel_mem_record(save);
                        if (cursor->iprec) {
                                KKASSERT(cursor->iprec == rec);
                                cursor->flags &= ~HAMMER_CURSOR_ATEMEM;
#if 0
                                cursor->scan.node =
                                        hammer_rec_rb_tree_RB_NEXT(rec);
#endif
                        } 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;
                }

                /*
                 * If the entries match exactly the memory entry typically
                 * specifies an on-disk deletion and we eat both entries.
                 *
                 * If the in-memory record is not an on-disk deletion we
                 * probably caught the syncer while it was syncing it to
                 * the media.  Since we hold a shared lock on the cursor,
                 * the in-memory record had better be marked deleted at
                 * this point.
                 */
                if (r == 0) {
                        if (cursor->iprec->type == HAMMER_MEM_RECORD_DEL) {
                                if ((cursor->flags & HAMMER_CURSOR_DELETE_VISIBILITY) == 0) {
                                        cursor->flags |= HAMMER_CURSOR_ATEDISK;
                                        cursor->flags |= HAMMER_CURSOR_ATEMEM;
                                        goto next_btree;
                                }
                        } else {
                                KKASSERT(hammer_ip_iterate_mem_good(cursor, cursor->iprec) == 0);
                                cursor->flags |= HAMMER_CURSOR_ATEMEM;
                                goto next_memory;
                        }
                }
                /* fall through to the memory entry */
        case HAMMER_CURSOR_ATEDISK:
                /*
                 * Only the memory entry is valid.  If the record is
                 * placemarking an on-disk deletion, we skip it unless
                 * the caller wants special record visibility.
                 */
                cursor->record = &cursor->iprec->rec;
                cursor->flags |= HAMMER_CURSOR_ATEMEM;
                if (cursor->iprec->type == HAMMER_MEM_RECORD_DEL) {
                        if ((cursor->flags & HAMMER_CURSOR_DELETE_VISIBILITY) == 0)
                                goto next_memory;
                }
                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->data 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->data = cursor->iprec->data;
                error = 0;
        } else {
                error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA);
        }
        return(error);
}

int
hammer_ip_resolve_record_and_data(hammer_cursor_t cursor)
{
        int error;

        if (cursor->iprec && cursor->record == &cursor->iprec->rec) {
                cursor->data = cursor->iprec->data;
                error = 0;
        } else {
                error = hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA |
                                                     HAMMER_CURSOR_GET_RECORD);
        }
        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;

#if 0
        kprintf("delete_range %p %016llx-%016llx\n", ip, ran_beg, ran_end);
#endif

        KKASSERT(trans->type == HAMMER_TRANS_FLS);
retry:
        hammer_init_cursor(trans, &cursor, &ip->cache[0]);

        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.flags |= HAMMER_CURSOR_DELETE_VISIBILITY;
        cursor.flags |= HAMMER_CURSOR_BACKEND;

        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,%d\n",
                                base->key - rec->base.data_len, 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 user records associated with an inode except the inode record
 * itself.  Directory entries are not deleted (they must be properly disposed
 * of or nlinks would get upset).
 */
int
hammer_ip_delete_range_all(hammer_transaction_t trans, hammer_inode_t ip,
                           int *countp)
{
        struct hammer_cursor cursor;
        hammer_record_ondisk_t rec;
        hammer_base_elm_t base;
        int error;

        KKASSERT(trans->type == HAMMER_TRANS_FLS);
retry:
        hammer_init_cursor(trans, &cursor, &ip->cache[0]);

        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;
        cursor.flags |= HAMMER_CURSOR_DELETE_VISIBILITY;
        cursor.flags |= HAMMER_CURSOR_BACKEND;

        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.
                 *
                 * Directory entries (and delete-on-disk directory entries)
                 * must be synced and cannot be deleted.
                 */
                if (rec->base.base.rec_type != HAMMER_RECTYPE_DIRENTRY) {
                        error = hammer_ip_delete_record(&cursor, trans->tid);
                        ++*countp;
                }
                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.
 *
 * This routine is only called from the backend.
 *
 * 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;

        KKASSERT(cursor->flags & HAMMER_CURSOR_BACKEND);

        /*
         * In-memory (unsynchronized) records can simply be freed.  This
         * only occurs in range iterations since all other records are
         * individually synchronized.  Thus there should be no confusion with
         * the interlock.
         */
        if (cursor->record == &cursor->iprec->rec) {
                KKASSERT((cursor->iprec->flags & HAMMER_RECF_INTERLOCK_BE) ==0);
                cursor->iprec->flags |= HAMMER_RECF_DELETED_FE;
                cursor->iprec->flags |= HAMMER_RECF_DELETED_BE;
                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->hmp;

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

                        /*
                         * An on-disk record cannot have the same delete_tid
                         * as its create_tid.  In a chain of record updates
                         * this could result in a duplicate record.
                         */
                        KKASSERT(elm->leaf.base.delete_tid != elm->leaf.base.create_tid);
                        hammer_modify_buffer(cursor->trans, cursor->record_buffer, &cursor->record->base.base.delete_tid, sizeof(hammer_tid_t));
                        cursor->record->base.base.delete_tid = tid;
                        hammer_modify_buffer_done(cursor->record_buffer);
                }
        }

        /*
         * 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_int16_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;
                }
        }
        if (error == 0) {
                hammer_blockmap_free(cursor->trans, rec_offset,
                                     sizeof(union hammer_record_ondisk));
        }
        if (error == 0) {
                switch(data_offset & HAMMER_OFF_ZONE_MASK) {
                case HAMMER_ZONE_LARGE_DATA:
                case HAMMER_ZONE_SMALL_DATA:
                        hammer_blockmap_free(cursor->trans,
                                             data_offset, data_len);
                        break;
                default:
                        break;
                }
        }
#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 we can remove a directory.  This routine checks whether
 * a directory is empty or not and enforces flush connectivity.
 *
 * Flush connectivity requires that we block if the target directory is
 * currently flushing, otherwise it may not end up in the same flush group.
 *
 * Returns 0 on success, ENOTEMPTY or EDEADLK (or other errors) on failure.
 */
int
hammer_ip_check_directory_empty(hammer_transaction_t trans,
                        hammer_cursor_t parent_cursor, hammer_inode_t ip)
{
        struct hammer_cursor cursor;
        int error;

#if 0
        /*
         * Check flush connectivity
         */
        if (ip->flush_state != HAMMER_FST_IDLE) {
                kprintf("FWAIT\n");
                hammer_done_cursor(parent_cursor);
                hammer_flush_inode(ip, HAMMER_FLUSH_FORCE|HAMMER_FLUSH_SIGNAL);
                hammer_wait_inode(ip);
                return (EDEADLK);
        }
#endif

        /*
         * Check directory empty
         */
        hammer_init_cursor(trans, &cursor, &ip->cache[0]);

        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);
}