PEP8: fix E305: expected 2 blank lines after class or function definition, found 1

[Samba.git] / source3 / locking / share_mode_lock.c

/*
   Unix SMB/CIFS implementation.
   Locking functions
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1992-2006
   Copyright (C) Volker Lendecke 2005

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   Revision History:

   12 aug 96: Erik.Devriendt@te6.siemens.be
   added support for shared memory implementation of share mode locking

   May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode
   locking to deal with multiple share modes per open file.

   September 1997. Jeremy Allison (jallison@whistle.com). Added oplock
   support.

   rewritten completely to use new tdb code. Tridge, Dec '99

   Added POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
   Added Unix Extensions POSIX locking support. Jeremy Allison Mar 2006.
*/

#include "includes.h"
#include "system/filesys.h"
#include "lib/util/server_id.h"
#include "locking/proto.h"
#include "smbd/globals.h"
#include "dbwrap/dbwrap.h"
#include "dbwrap/dbwrap_open.h"
#include "../libcli/security/security.h"
#include "serverid.h"
#include "messages.h"
#include "util_tdb.h"
#include "../librpc/gen_ndr/ndr_open_files.h"
#include "source3/lib/dbwrap/dbwrap_watch.h"
#include "locking/leases_db.h"
#include "../lib/util/memcache.h"
#include "lib/util/tevent_ntstatus.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

#define NO_LOCKING_COUNT (-1)

/* the locking database handle */
static struct db_context *lock_db;

static bool locking_init_internal(bool read_only)
{
        struct db_context *backend;
        char *db_path;

        brl_init(read_only);

        if (lock_db)
                return True;

        db_path = lock_path(talloc_tos(), "locking.tdb");
        if (db_path == NULL) {
                return false;
        }

        backend = db_open(NULL, db_path,
                          SMB_OPEN_DATABASE_TDB_HASH_SIZE,
                          TDB_DEFAULT|TDB_VOLATILE|TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
                          read_only?O_RDONLY:O_RDWR|O_CREAT, 0644,
                          DBWRAP_LOCK_ORDER_1, DBWRAP_FLAG_NONE);
        TALLOC_FREE(db_path);
        if (!backend) {
                DEBUG(0,("ERROR: Failed to initialise locking database\n"));
                return False;
        }

        lock_db = db_open_watched(NULL, &backend, server_messaging_context());
        if (lock_db == NULL) {
                DBG_ERR("db_open_watched failed\n");
                TALLOC_FREE(backend);
                return false;
        }

        if (!posix_locking_init(read_only)) {
                TALLOC_FREE(lock_db);
                return False;
        }

        return True;
}

bool locking_init(void)
{
        return locking_init_internal(false);
}

bool locking_init_readonly(void)
{
        return locking_init_internal(true);
}

/*******************************************************************
 Deinitialize the share_mode management.
******************************************************************/

bool locking_end(void)
{
        brl_shutdown();
        TALLOC_FREE(lock_db);
        return true;
}

/*******************************************************************
 Form a static locking key for a dev/inode pair.
******************************************************************/

static TDB_DATA locking_key(const struct file_id *id)
{
        return make_tdb_data((const uint8_t *)id, sizeof(*id));
}

/*******************************************************************
 Share mode cache utility functions that store/delete/retrieve
 entries from memcache.

 For now share the statcache (global cache) memory space. If
 a lock record gets orphaned (which shouldn't happen as we're
 using the same locking_key data as lookup) it will eventually
 fall out of the cache via the normal LRU trim mechanism. If
 necessary we can always make this a separate (smaller) cache.
******************************************************************/

static const DATA_BLOB memcache_key(const struct file_id *id)
{
        return data_blob_const((const void *)id, sizeof(*id));
}

static void share_mode_memcache_delete(struct share_mode_data *d)
{
        const DATA_BLOB key = memcache_key(&d->id);

        DEBUG(10,("deleting entry for file %s seq 0x%llu key %s\n",
                d->base_name,
                (unsigned long long) d->sequence_number,
                file_id_string(talloc_tos(), &d->id)));

        memcache_delete(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);
}

static void share_mode_memcache_store(struct share_mode_data *d)
{
        const DATA_BLOB key = memcache_key(&d->id);

        DEBUG(10,("stored entry for file %s seq 0x%llu key %s\n",
                d->base_name,
                (unsigned long long) d->sequence_number,
                file_id_string(talloc_tos(), &d->id)));

        /* Ensure everything stored in the cache is pristine. */
        d->modified = false;
        d->fresh = false;

        /*
         * Ensure the memory going into the cache
         * doesn't have a destructor so it can be
         * cleanly freed by share_mode_memcache_delete().
         */
        talloc_set_destructor(d, NULL);

        /* Cache will own d after this call. */
        memcache_add_talloc(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key,
                        &d);
}

/*
 * NB. We use ndr_pull_hyper on a stack-created
 * struct ndr_pull with no talloc allowed, as we
 * need this to be really fast as an ndr-peek into
 * the first 8 bytes of the blob.
 */

static enum ndr_err_code get_blob_sequence_number(DATA_BLOB *blob,
                                                uint64_t *pseq)
{
        struct ndr_pull ndr = {.data = blob->data, .data_size = blob->length};
        NDR_CHECK(ndr_pull_hyper(&ndr, NDR_SCALARS, pseq));
        return NDR_ERR_SUCCESS;
}

static int share_mode_data_nofree_destructor(struct share_mode_data *d)
{
        return -1;
}

static struct share_mode_data *share_mode_memcache_fetch(TALLOC_CTX *mem_ctx,
                                        const TDB_DATA id_key,
                                        DATA_BLOB *blob)
{
        enum ndr_err_code ndr_err;
        struct share_mode_data *d;
        uint64_t sequence_number;
        void *ptr;
        struct file_id id;
        DATA_BLOB key;

        /* Ensure this is a locking_key record. */
        if (id_key.dsize != sizeof(id)) {
                return NULL;
        }

        memcpy(&id, id_key.dptr, id_key.dsize);
        key = memcache_key(&id);

        ptr = memcache_lookup_talloc(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);
        if (ptr == NULL) {
                DEBUG(10,("failed to find entry for key %s\n",
                        file_id_string(mem_ctx, &id)));
                return NULL;
        }
        /* sequence number key is at start of blob. */
        ndr_err = get_blob_sequence_number(blob, &sequence_number);
        if (ndr_err != NDR_ERR_SUCCESS) {
                /* Bad blob. Remove entry. */
                DEBUG(10,("bad blob %u key %s\n",
                        (unsigned int)ndr_err,
                        file_id_string(mem_ctx, &id)));
                memcache_delete(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);
                return NULL;
        }

        d = (struct share_mode_data *)ptr;
        if (d->sequence_number != sequence_number) {
                DEBUG(10,("seq changed (cached 0x%llu) (new 0x%llu) "
                        "for key %s\n",
                        (unsigned long long)d->sequence_number,
                        (unsigned long long)sequence_number,
                        file_id_string(mem_ctx, &id)));
                /* Cache out of date. Remove entry. */
                memcache_delete(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);
                return NULL;
        }

        /* Move onto mem_ctx. */
        d = talloc_move(mem_ctx, &ptr);

        /*
         * Now we own d, prevent the cache from freeing it
         * when we delete the entry.
         */
        talloc_set_destructor(d, share_mode_data_nofree_destructor);

        /* Remove from the cache. We own it now. */
        memcache_delete(NULL,
                        SHARE_MODE_LOCK_CACHE,
                        key);

        /* And reset the destructor to none. */
        talloc_set_destructor(d, NULL);

        DEBUG(10,("fetched entry for file %s seq 0x%llu key %s\n",
                d->base_name,
                (unsigned long long)d->sequence_number,
                file_id_string(mem_ctx, &id)));

        return d;
}

/*******************************************************************
 Get all share mode entries for a dev/inode pair.
********************************************************************/

static struct share_mode_data *parse_share_modes(TALLOC_CTX *mem_ctx,
                                                const TDB_DATA key,
                                                const TDB_DATA dbuf)
{
        struct share_mode_data *d;
        enum ndr_err_code ndr_err;
        uint32_t i;
        DATA_BLOB blob;

        blob.data = dbuf.dptr;
        blob.length = dbuf.dsize;

        /* See if we already have a cached copy of this key. */
        d = share_mode_memcache_fetch(mem_ctx, key, &blob);
        if (d != NULL) {
                return d;
        }

        d = talloc(mem_ctx, struct share_mode_data);
        if (d == NULL) {
                DEBUG(0, ("talloc failed\n"));
                goto fail;
        }

        ndr_err = ndr_pull_struct_blob_all(
                &blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DEBUG(1, ("ndr_pull_share_mode_lock failed: %s\n",
                          ndr_errstr(ndr_err)));
                goto fail;
        }

        /*
         * Initialize the values that are [skip] or [ignore]
         * in the idl. The NDR code does not initialize them.
         */

        for (i=0; i<d->num_share_modes; i++) {
                d->share_modes[i].stale = false;
        }
        d->modified = false;
        d->fresh = false;

        if (DEBUGLEVEL >= 10) {
                DEBUG(10, ("parse_share_modes:\n"));
                NDR_PRINT_DEBUG(share_mode_data, d);
        }

        return d;
fail:
        TALLOC_FREE(d);
        return NULL;
}

/*******************************************************************
 Create a storable data blob from a modified share_mode_data struct.
********************************************************************/

static TDB_DATA unparse_share_modes(struct share_mode_data *d)
{
        DATA_BLOB blob;
        enum ndr_err_code ndr_err;

        if (DEBUGLEVEL >= 10) {
                DEBUG(10, ("unparse_share_modes:\n"));
                NDR_PRINT_DEBUG(share_mode_data, d);
        }

        share_mode_memcache_delete(d);

        /* Update the sequence number. */
        d->sequence_number += 1;

        remove_stale_share_mode_entries(d);

        if (d->num_share_modes == 0) {
                DEBUG(10, ("No used share mode found\n"));
                return make_tdb_data(NULL, 0);
        }

        ndr_err = ndr_push_struct_blob(
                &blob, d, d, (ndr_push_flags_fn_t)ndr_push_share_mode_data);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                smb_panic("ndr_push_share_mode_lock failed");
        }

        return make_tdb_data(blob.data, blob.length);
}

/*******************************************************************
 If modified, store the share_mode_data back into the database.
********************************************************************/

static int share_mode_data_destructor(struct share_mode_data *d)
{
        NTSTATUS status;
        TDB_DATA data;

        if (!d->modified) {
                return 0;
        }

        data = unparse_share_modes(d);

        if (data.dptr == NULL) {
                if (!d->fresh) {
                        /* There has been an entry before, delete it */

                        status = dbwrap_record_delete(d->record);
                        if (!NT_STATUS_IS_OK(status)) {
                                char *errmsg;

                                DEBUG(0, ("delete_rec returned %s\n",
                                          nt_errstr(status)));

                                if (asprintf(&errmsg, "could not delete share "
                                             "entry: %s\n",
                                             nt_errstr(status)) == -1) {
                                        smb_panic("could not delete share"
                                                  "entry");
                                }
                                smb_panic(errmsg);
                        }
                }
                /*
                 * Nothing to store in cache - allow the normal
                 * release of record lock and memory free.
                 */
                return 0;
        }

        status = dbwrap_record_store(d->record, data, TDB_REPLACE);
        if (!NT_STATUS_IS_OK(status)) {
                char *errmsg;

                DEBUG(0, ("store returned %s\n", nt_errstr(status)));

                if (asprintf(&errmsg, "could not store share mode entry: %s",
                             nt_errstr(status)) == -1) {
                        smb_panic("could not store share mode entry");
                }
                smb_panic(errmsg);
        }

        /*
         * Release the record lock before putting in the cache.
         */
        TALLOC_FREE(d->record);

        /*
         * Release the dptr as well before reparenting to NULL
         * (in-memory cache) context.
         */
        TALLOC_FREE(data.dptr);
        /*
         * Reparent d into the in-memory cache so it can be reused if the
         * sequence number matches. See parse_share_modes()
         * for details.
         */

        share_mode_memcache_store(d);
        return -1;
}

/*******************************************************************
 Allocate a new share_mode_data struct, mark it unmodified.
 fresh is set to note that currently there is no database entry.
********************************************************************/

static struct share_mode_data *fresh_share_mode_lock(
        TALLOC_CTX *mem_ctx, const char *servicepath,
        const struct smb_filename *smb_fname,
        const struct timespec *old_write_time)
{
        struct share_mode_data *d;

        if ((servicepath == NULL) || (smb_fname == NULL) ||
            (old_write_time == NULL)) {
                return NULL;
        }

        d = talloc_zero(mem_ctx, struct share_mode_data);
        if (d == NULL) {
                goto fail;
        }
        /* New record - new sequence number. */
        generate_random_buffer((uint8_t *)&d->sequence_number, 8);

        d->base_name = talloc_strdup(d, smb_fname->base_name);
        if (d->base_name == NULL) {
                goto fail;
        }
        if (smb_fname->stream_name != NULL) {
                d->stream_name = talloc_strdup(d, smb_fname->stream_name);
                if (d->stream_name == NULL) {
                        goto fail;
                }
        }
        d->servicepath = talloc_strdup(d, servicepath);
        if (d->servicepath == NULL) {
                goto fail;
        }
        d->old_write_time = *old_write_time;
        d->modified = false;
        d->fresh = true;
        return d;
fail:
        DEBUG(0, ("talloc failed\n"));
        TALLOC_FREE(d);
        return NULL;
}

/*******************************************************************
 Either fetch a share mode from the database, or allocate a fresh
 one if the record doesn't exist.
********************************************************************/

static struct share_mode_lock *get_share_mode_lock_internal(
        TALLOC_CTX *mem_ctx, struct file_id id,
        const char *servicepath, const struct smb_filename *smb_fname,
        const struct timespec *old_write_time)
{
        struct share_mode_lock *lck;
        struct share_mode_data *d;
        struct db_record *rec;
        TDB_DATA key = locking_key(&id);
        TDB_DATA value;

        rec = dbwrap_fetch_locked(lock_db, mem_ctx, key);
        if (rec == NULL) {
                DEBUG(3, ("Could not lock share entry\n"));
                return NULL;
        }

        value = dbwrap_record_get_value(rec);

        if (value.dptr == NULL) {
                d = fresh_share_mode_lock(mem_ctx, servicepath, smb_fname,
                                          old_write_time);
        } else {
                d = parse_share_modes(mem_ctx, key, value);
        }

        if (d == NULL) {
                DEBUG(5, ("get_share_mode_lock_internal: "
                        "Could not get share mode lock\n"));
                TALLOC_FREE(rec);
                return NULL;
        }
        d->id = id;
        d->record = talloc_move(d, &rec);
        talloc_set_destructor(d, share_mode_data_destructor);

        lck = talloc(mem_ctx, struct share_mode_lock);
        if (lck == NULL) {
                DEBUG(1, ("talloc failed\n"));
                TALLOC_FREE(d);
                return NULL;
        }
        lck->data = talloc_move(lck, &d);
        return lck;
}

/*
 * We can only ever have one share mode locked. Users of
 * get_share_mode_lock never see this, it will be refcounted by
 * talloc_reference.
 */
static struct share_mode_lock *the_lock;
static struct file_id the_lock_id;

static int the_lock_destructor(struct share_mode_lock *l)
{
        the_lock = NULL;
        ZERO_STRUCT(the_lock_id);
        return 0;
}

/*******************************************************************
 Get a share_mode_lock, Reference counted to allow nested calls.
********************************************************************/

struct share_mode_lock *get_share_mode_lock(
        TALLOC_CTX *mem_ctx,
        struct file_id id,
        const char *servicepath,
        const struct smb_filename *smb_fname,
        const struct timespec *old_write_time)
{
        struct share_mode_lock *lck;

        lck = talloc(mem_ctx, struct share_mode_lock);
        if (lck == NULL) {
                DEBUG(1, ("talloc failed\n"));
                return NULL;
        }

        if (the_lock == NULL) {
                the_lock = get_share_mode_lock_internal(
                        lck, id, servicepath, smb_fname, old_write_time);
                if (the_lock == NULL) {
                        goto fail;
                }
                talloc_set_destructor(the_lock, the_lock_destructor);
                the_lock_id = id;
        } else {
                if (!file_id_equal(&the_lock_id, &id)) {
                        DEBUG(1, ("Can not lock two share modes "
                                  "simultaneously\n"));
                        goto fail;
                }
                if (talloc_reference(lck, the_lock) == NULL) {
                        DEBUG(1, ("talloc_reference failed\n"));
                        goto fail;
                }
        }
        lck->data = the_lock->data;
        return lck;
fail:
        TALLOC_FREE(lck);
        return NULL;
}

struct fetch_share_mode_unlocked_state {
        TALLOC_CTX *mem_ctx;
        struct share_mode_lock *lck;
};

static void fetch_share_mode_unlocked_parser(
        TDB_DATA key, TDB_DATA data, void *private_data)
{
        struct fetch_share_mode_unlocked_state *state = private_data;

        if (data.dsize == 0) {
                /* Likely a ctdb tombstone record, ignore it */
                return;
        }

        state->lck = talloc(state->mem_ctx, struct share_mode_lock);
        if (state->lck == NULL) {
                DEBUG(0, ("talloc failed\n"));
                return;
        }

        state->lck->data = parse_share_modes(state->lck, key, data);
}

/*******************************************************************
 Get a share_mode_lock without locking the database or reference
 counting. Used by smbstatus to display existing share modes.
********************************************************************/

struct share_mode_lock *fetch_share_mode_unlocked(TALLOC_CTX *mem_ctx,
                                                  struct file_id id)
{
        struct fetch_share_mode_unlocked_state state = { .mem_ctx = mem_ctx };
        TDB_DATA key = locking_key(&id);
        NTSTATUS status;

        status = dbwrap_parse_record(
                lock_db, key, fetch_share_mode_unlocked_parser, &state);
        if (!NT_STATUS_IS_OK(status)) {
                return NULL;
        }
        return state.lck;
}

static void fetch_share_mode_done(struct tevent_req *subreq);

struct fetch_share_mode_state {
        struct file_id id;
        TDB_DATA key;
        struct share_mode_lock *lck;
        enum dbwrap_req_state req_state;
};

/**
 * @brief Get a share_mode_lock without locking or refcounting
 *
 * This can be used in a clustered Samba environment where the async dbwrap
 * request is sent over a socket to the local ctdbd. If the send queue is full
 * and the caller was issuing multiple async dbwrap requests in a loop, the
 * caller knows it's probably time to stop sending requests for now and try
 * again later.
 *
 * @param[in]  mem_ctx The talloc memory context to use.
 *
 * @param[in]  ev      The event context to work on.
 *
 * @param[in]  id      The file id for the locking.tdb key
 *
 * @param[out] queued  This boolean out parameter tells the caller whether the
 *                     async request is blocked in a full send queue:
 *
 *                     false := request is dispatched
 *
 *                     true  := send queue is full, request waiting to be
 *                              dispatched
 *
 * @return             The new async request, NULL on error.
 **/
struct tevent_req *fetch_share_mode_send(TALLOC_CTX *mem_ctx,
                                         struct tevent_context *ev,
                                         struct file_id id,
                                         bool *queued)
{
        struct tevent_req *req = NULL;
        struct fetch_share_mode_state *state = NULL;
        struct tevent_req *subreq = NULL;

        *queued = false;

        req = tevent_req_create(mem_ctx, &state,
                                struct fetch_share_mode_state);
        if (req == NULL) {
                return NULL;
        }

        state->id = id;
        state->key = locking_key(&state->id);
        state->lck = talloc_zero(state, struct share_mode_lock);
        if (tevent_req_nomem(state->lck, req)) {
                return tevent_req_post(req, ev);
        }

        subreq = dbwrap_parse_record_send(state,
                                          ev,
                                          lock_db,
                                          state->key,
                                          fetch_share_mode_unlocked_parser,
                                          state->lck,
                                          &state->req_state);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, fetch_share_mode_done, req);

        if (state->req_state < DBWRAP_REQ_DISPATCHED) {
                *queued = true;
        }
        return req;
}

static void fetch_share_mode_done(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        NTSTATUS status;

        status = dbwrap_parse_record_recv(subreq);
        TALLOC_FREE(subreq);
        if (tevent_req_nterror(req, status)) {
                return;
        }

        tevent_req_done(req);
        return;
}

NTSTATUS fetch_share_mode_recv(struct tevent_req *req,
                               TALLOC_CTX *mem_ctx,
                               struct share_mode_lock **_lck)
{
        struct fetch_share_mode_state *state = tevent_req_data(
                req, struct fetch_share_mode_state);
        struct share_mode_lock *lck = NULL;

        NTSTATUS status;

        if (tevent_req_is_nterror(req, &status)) {
                tevent_req_received(req);
                return status;
        }

        if (state->lck->data == NULL) {
                tevent_req_received(req);
                return NT_STATUS_NOT_FOUND;
        }

        lck = talloc_move(mem_ctx, &state->lck);

        if (DEBUGLEVEL >= 10) {
                DBG_DEBUG("share_mode_data:\n");
                NDR_PRINT_DEBUG(share_mode_data, lck->data);
        }

        *_lck = lck;
        tevent_req_received(req);
        return NT_STATUS_OK;
}

struct share_mode_forall_state {
        int (*fn)(struct file_id fid, const struct share_mode_data *data,
                  void *private_data);
        void *private_data;
};

static int share_mode_traverse_fn(struct db_record *rec, void *_state)
{
        struct share_mode_forall_state *state =
                (struct share_mode_forall_state *)_state;
        uint32_t i;
        TDB_DATA key;
        TDB_DATA value;
        DATA_BLOB blob;
        enum ndr_err_code ndr_err;
        struct share_mode_data *d;
        struct file_id fid;
        int ret;

        key = dbwrap_record_get_key(rec);
        value = dbwrap_record_get_value(rec);

        /* Ensure this is a locking_key record. */
        if (key.dsize != sizeof(fid)) {
                return 0;
        }
        memcpy(&fid, key.dptr, sizeof(fid));

        d = talloc(talloc_tos(), struct share_mode_data);
        if (d == NULL) {
                return 0;
        }

        blob.data = value.dptr;
        blob.length = value.dsize;

        ndr_err = ndr_pull_struct_blob_all(
                &blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DEBUG(1, ("ndr_pull_share_mode_lock failed\n"));
                return 0;
        }

        for (i=0; i<d->num_share_modes; i++) {
                d->share_modes[i].stale = false;
        }

        if (DEBUGLEVEL > 10) {
                DEBUG(11, ("parse_share_modes:\n"));
                NDR_PRINT_DEBUG(share_mode_data, d);
        }

        ret = state->fn(fid, d, state->private_data);

        TALLOC_FREE(d);
        return ret;
}

int share_mode_forall(int (*fn)(struct file_id fid,
                                const struct share_mode_data *data,
                                void *private_data),
                      void *private_data)
{
        struct share_mode_forall_state state = {
                .fn = fn,
                .private_data = private_data
        };
        NTSTATUS status;
        int count;

        if (lock_db == NULL) {
                return 0;
        }

        status = dbwrap_traverse_read(lock_db, share_mode_traverse_fn,
                                      &state, &count);
        if (!NT_STATUS_IS_OK(status)) {
                return -1;
        }

        return count;
}

struct share_entry_forall_state {
        int (*fn)(struct file_id fid,
                  const struct share_mode_data *data,
                  const struct share_mode_entry *entry,
                  void *private_data);
        void *private_data;
};

static int share_entry_traverse_fn(struct file_id fid,
                                   const struct share_mode_data *data,
                                   void *private_data)
{
        struct share_entry_forall_state *state = private_data;
        uint32_t i;

        for (i=0; i<data->num_share_modes; i++) {
                int ret;

                ret = state->fn(fid,
                                data,
                                &data->share_modes[i],
                                state->private_data);
                if (ret != 0) {
                        return ret;
                }
        }

        return 0;
}

/*******************************************************************
 Call the specified function on each entry under management by the
 share mode system.
********************************************************************/

int share_entry_forall(int (*fn)(struct file_id fid,
                                 const struct share_mode_data *data,
                                 const struct share_mode_entry *entry,
                                 void *private_data),
                      void *private_data)
{
        struct share_entry_forall_state state = {
                .fn = fn, .private_data = private_data };

        return share_mode_forall(share_entry_traverse_fn, &state);
}

bool share_mode_cleanup_disconnected(struct file_id fid,
                                     uint64_t open_persistent_id)
{
        bool ret = false;
        TALLOC_CTX *frame = talloc_stackframe();
        unsigned n;
        struct share_mode_data *data;
        struct share_mode_lock *lck;
        bool ok;

        lck = get_existing_share_mode_lock(frame, fid);
        if (lck == NULL) {
                DEBUG(5, ("share_mode_cleanup_disconnected: "
                          "Could not fetch share mode entry for %s\n",
                          file_id_string(frame, &fid)));
                goto done;
        }
        data = lck->data;

        for (n=0; n < data->num_share_modes; n++) {
                struct share_mode_entry *entry = &data->share_modes[n];

                if (!server_id_is_disconnected(&entry->pid)) {
                        struct server_id_buf tmp;
                        DEBUG(5, ("share_mode_cleanup_disconnected: "
                                  "file (file-id='%s', servicepath='%s', "
                                  "base_name='%s%s%s') "
                                  "is used by server %s ==> do not cleanup\n",
                                  file_id_string(frame, &fid),
                                  data->servicepath,
                                  data->base_name,
                                  (data->stream_name == NULL)
                                  ? "" : "', stream_name='",
                                  (data->stream_name == NULL)
                                  ? "" : data->stream_name,
                                  server_id_str_buf(entry->pid, &tmp)));
                        goto done;
                }
                if (open_persistent_id != entry->share_file_id) {
                        DEBUG(5, ("share_mode_cleanup_disconnected: "
                                  "entry for file "
                                  "(file-id='%s', servicepath='%s', "
                                  "base_name='%s%s%s') "
                                  "has share_file_id %llu but expected %llu"
                                  "==> do not cleanup\n",
                                  file_id_string(frame, &fid),
                                  data->servicepath,
                                  data->base_name,
                                  (data->stream_name == NULL)
                                  ? "" : "', stream_name='",
                                  (data->stream_name == NULL)
                                  ? "" : data->stream_name,
                                  (unsigned long long)entry->share_file_id,
                                  (unsigned long long)open_persistent_id));
                        goto done;
                }
        }

        for (n=0; n < data->num_leases; n++) {
                struct share_mode_lease *l = &data->leases[n];
                NTSTATUS status;

                status = leases_db_del(&l->client_guid, &l->lease_key, &fid);

                DEBUG(10, ("%s: leases_db_del returned %s\n", __func__,
                           nt_errstr(status)));
        }

        ok = brl_cleanup_disconnected(fid, open_persistent_id);
        if (!ok) {
                DEBUG(10, ("share_mode_cleanup_disconnected: "
                           "failed to clean up byte range locks associated "
                           "with file (file-id='%s', servicepath='%s', "
                           "base_name='%s%s%s') and open_persistent_id %llu "
                           "==> do not cleanup\n",
                           file_id_string(frame, &fid),
                           data->servicepath,
                           data->base_name,
                           (data->stream_name == NULL)
                           ? "" : "', stream_name='",
                           (data->stream_name == NULL)
                           ? "" : data->stream_name,
                           (unsigned long long)open_persistent_id));
                goto done;
        }

        DEBUG(10, ("share_mode_cleanup_disconnected: "
                   "cleaning up %u entries for file "
                   "(file-id='%s', servicepath='%s', "
                   "base_name='%s%s%s') "
                   "from open_persistent_id %llu\n",
                   data->num_share_modes,
                   file_id_string(frame, &fid),
                   data->servicepath,
                   data->base_name,
                   (data->stream_name == NULL)
                   ? "" : "', stream_name='",
                   (data->stream_name == NULL)
                   ? "" : data->stream_name,
                   (unsigned long long)open_persistent_id));

        data->num_share_modes = 0;
        data->num_leases = 0;
        data->modified = true;

        ret = true;
done:
        talloc_free(frame);
        return ret;
}