smbd: Rename lck2->rw_probe in brl_conflict_other

[Samba.git] / source3 / smbd / notify_internal.c

/*
   Unix SMB/CIFS implementation.

   Copyright (C) Andrew Tridgell 2006
   Copyright (C) Volker Lendecke 2012

   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/>.
*/

/*
  this is the change notify database. It implements mechanisms for
  storing current change notify waiters in a tdb, and checking if a
  given event matches any of the stored notify waiters.
*/

#include "includes.h"
#include "system/filesys.h"
#include "librpc/gen_ndr/ndr_notify.h"
#include "dbwrap/dbwrap.h"
#include "dbwrap/dbwrap_open.h"
#include "dbwrap/dbwrap_tdb.h"
#include "smbd/smbd.h"
#include "messages.h"
#include "lib/tdb_wrap/tdb_wrap.h"
#include "util_tdb.h"
#include "lib/param/param.h"
#include "lib/dbwrap/dbwrap_cache.h"
#include "ctdb_srvids.h"
#include "ctdbd_conn.h"
#include "ctdb_conn.h"
#include "lib/util/tevent_unix.h"

struct notify_list {
        struct notify_list *next, *prev;
        const char *path;
        void (*callback)(void *, struct timespec, const struct notify_event *);
        void *private_data;
};

struct notify_context {
        struct messaging_context *msg;
        struct notify_list *list;

        /*
         * The notify database is split up into two databases: One
         * relatively static index db and the real notify db with the
         * volatile entries.
         */

        /*
         * "db_notify" is indexed by pathname. Per record it stores an
         * array of notify_db_entry structs. These represent the
         * notify records as requested by the smb client. This
         * database is always held locally, it is never clustered.
         */
        struct db_context *db_notify;

        /*
         * "db_index" is indexed by pathname. The records are an array
         * of VNNs which have any interest in notifies for this path
         * name.
         *
         * In the non-clustered case this database is cached in RAM by
         * means of db_cache_open, which maintains a cache per
         * process. Cache consistency is maintained by the tdb
         * sequence number.
         *
         * In the clustered case right now we can not use the tdb
         * sequence number, but by means of read only records we
         * should be able to avoid a lot of full migrations.
         *
         * In both cases, it is important to keep the update
         * operations to db_index to a minimum. This is achieved by
         * delayed deletion. When a db_notify is initially created,
         * the db_index record is also created. When more notifies are
         * added for a path, then only the db_notify record needs to be
         * modified, the db_index record is not touched. When the last
         * entry from the db_notify record is deleted, the db_index
         * record is not immediately deleted. Instead, the db_notify
         * record is replaced with a current timestamp. A regular
         * cleanup process will delete all db_index records that are
         * older than a minute.
         */
        struct db_context *db_index;
};

static void notify_trigger_local(struct notify_context *notify,
                                 uint32_t action, uint32_t filter,
                                 const char *path, size_t path_len,
                                 bool recursive);
static NTSTATUS notify_send(struct notify_context *notify,
                            struct server_id *pid,
                            const char *path, uint32_t action,
                            void *private_data);
static NTSTATUS notify_add_entry(struct db_record *rec,
                                 const struct notify_db_entry *e,
                                 bool *p_add_idx);
static NTSTATUS notify_add_idx(struct db_record *rec, uint32_t vnn);

static NTSTATUS notify_del_entry(struct db_record *rec,
                                 const struct server_id *pid,
                                 void *private_data);
static NTSTATUS notify_del_idx(struct db_record *rec, uint32_t vnn);

static int notify_context_destructor(struct notify_context *notify);

static void notify_handler(struct messaging_context *msg_ctx,
                           void *private_data, uint32_t msg_type,
                           struct server_id server_id, DATA_BLOB *data);

struct notify_context *notify_init(TALLOC_CTX *mem_ctx,
                                   struct messaging_context *msg,
                                   struct tevent_context *ev)
{
        struct loadparm_context *lp_ctx;
        struct notify_context *notify;

        notify = talloc(mem_ctx, struct notify_context);
        if (notify == NULL) {
                goto fail;
        }
        notify->msg = msg;
        notify->list = NULL;

        lp_ctx = loadparm_init_s3(notify, loadparm_s3_helpers());
        notify->db_notify = db_open_tdb(
                notify, lp_ctx, lock_path("notify.tdb"),
                0, TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
                O_RDWR|O_CREAT, 0644, DBWRAP_LOCK_ORDER_2, DBWRAP_FLAG_NONE);
                talloc_unlink(notify, lp_ctx);
        if (notify->db_notify == NULL) {
                goto fail;
        }
        notify->db_index = db_open(
                notify, lock_path("notify_index.tdb"),
                0, TDB_SEQNUM|TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
                O_RDWR|O_CREAT, 0644, DBWRAP_LOCK_ORDER_3, DBWRAP_FLAG_NONE);
        if (notify->db_index == NULL) {
                goto fail;
        }
        if (!lp_clustering()) {
                notify->db_index = db_open_cache(notify, notify->db_index);
                if (notify->db_index == NULL) {
                        goto fail;
                }
        }

        if (notify->msg != NULL) {
                NTSTATUS status;

                status = messaging_register(notify->msg, notify,
                                            MSG_PVFS_NOTIFY, notify_handler);
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(1, ("messaging_register returned %s\n",
                                  nt_errstr(status)));
                        goto fail;
                }
        }

        talloc_set_destructor(notify, notify_context_destructor);

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

static int notify_context_destructor(struct notify_context *notify)
{
        DEBUG(10, ("notify_context_destructor called\n"));

        if (notify->msg != NULL) {
                messaging_deregister(notify->msg, MSG_PVFS_NOTIFY, notify);
        }

        while (notify->list != NULL) {
                DEBUG(10, ("Removing private_data=%p\n",
                           notify->list->private_data));
                notify_remove(notify, notify->list->private_data);
        }
        return 0;
}

NTSTATUS notify_add(struct notify_context *notify,
                    const char *path, uint32_t filter, uint32_t subdir_filter,
                    void (*callback)(void *, struct timespec,
                                     const struct notify_event *),
                    void *private_data)
{
        struct notify_db_entry e;
        struct notify_list *listel;
        struct db_record *notify_rec, *idx_rec;
        bool add_idx;
        NTSTATUS status;
        TDB_DATA key, notify_copy;

        if (notify == NULL) {
                return NT_STATUS_NOT_IMPLEMENTED;
        }

        DEBUG(10, ("notify_add: path=[%s], private_data=%p\n", path,
                   private_data));

        listel = talloc(notify, struct notify_list);
        if (listel == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        listel->callback = callback;
        listel->private_data = private_data;
        listel->path = talloc_strdup(listel, path);
        if (listel->path == NULL) {
                TALLOC_FREE(listel);
                return NT_STATUS_NO_MEMORY;
        }
        DLIST_ADD(notify->list, listel);

        ZERO_STRUCT(e);
        e.filter = filter;
        e.subdir_filter = subdir_filter;
        e.server = messaging_server_id(notify->msg);
        e.private_data = private_data;

        key = string_tdb_data(path);

        notify_rec = dbwrap_fetch_locked(notify->db_notify,
                                         talloc_tos(), key);
        if (notify_rec == NULL) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto fail;
        }

        /*
         * Make a copy of the notify_rec for easy restore in case
         * updating the index_rec fails;
         */
        notify_copy = dbwrap_record_get_value(notify_rec);
        if (notify_copy.dsize != 0) {
                notify_copy.dptr = (uint8_t *)talloc_memdup(
                        notify_rec, notify_copy.dptr,
                        notify_copy.dsize);
                if (notify_copy.dptr == NULL) {
                        TALLOC_FREE(notify_rec);
                        status = NT_STATUS_NO_MEMORY;
                        goto fail;
                }
        }

        if (DEBUGLEVEL >= 10) {
                NDR_PRINT_DEBUG(notify_db_entry, &e);
        }

        status = notify_add_entry(notify_rec, &e, &add_idx);
        if (!NT_STATUS_IS_OK(status)) {
                goto fail;
        }
        if (!add_idx) {
                /*
                 * Someone else has added the idx entry already
                 */
                TALLOC_FREE(notify_rec);
                return NT_STATUS_OK;
        }

        idx_rec = dbwrap_fetch_locked(notify->db_index,
                                      talloc_tos(), key);
        if (idx_rec == NULL) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto restore_notify;
        }
        status = notify_add_idx(idx_rec, get_my_vnn());
        if (!NT_STATUS_IS_OK(status)) {
                goto restore_notify;
        }

        TALLOC_FREE(idx_rec);
        TALLOC_FREE(notify_rec);
        return NT_STATUS_OK;

restore_notify:
        if (notify_copy.dsize != 0) {
                dbwrap_record_store(notify_rec, notify_copy, 0);
        } else {
                dbwrap_record_delete(notify_rec);
        }
        TALLOC_FREE(notify_rec);
fail:
        DLIST_REMOVE(notify->list, listel);
        TALLOC_FREE(listel);
        return status;
}

static NTSTATUS notify_add_entry(struct db_record *rec,
                                 const struct notify_db_entry *e,
                                 bool *p_add_idx)
{
        TDB_DATA value = dbwrap_record_get_value(rec);
        struct notify_db_entry *entries;
        size_t num_entries;
        bool add_idx = true;
        NTSTATUS status;

        if (value.dsize == sizeof(time_t)) {
                DEBUG(10, ("Re-using deleted entry\n"));
                value.dsize = 0;
                add_idx = false;
        }

        if ((value.dsize % sizeof(struct notify_db_entry)) != 0) {
                DEBUG(1, ("Invalid value.dsize = %u\n",
                          (unsigned)value.dsize));
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }
        num_entries = value.dsize / sizeof(struct notify_db_entry);

        if (num_entries != 0) {
                add_idx = false;
        }

        entries = talloc_array(rec, struct notify_db_entry, num_entries + 1);
        if (entries == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        memcpy(entries, value.dptr, value.dsize);

        entries[num_entries] = *e;
        value = make_tdb_data((uint8_t *)entries, talloc_get_size(entries));
        status = dbwrap_record_store(rec, value, 0);
        TALLOC_FREE(entries);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }
        *p_add_idx = add_idx;
        return NT_STATUS_OK;
}

static NTSTATUS notify_add_idx(struct db_record *rec, uint32_t vnn)
{
        TDB_DATA value = dbwrap_record_get_value(rec);
        uint32_t *vnns;
        size_t i, num_vnns;
        NTSTATUS status;

        if ((value.dsize % sizeof(uint32_t)) != 0) {
                DEBUG(1, ("Invalid value.dsize = %u\n",
                          (unsigned)value.dsize));
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }
        num_vnns = value.dsize / sizeof(uint32_t);
        vnns = (uint32_t *)value.dptr;

        for (i=0; i<num_vnns; i++) {
                if (vnns[i] == vnn) {
                        return NT_STATUS_OK;
                }
                if (vnns[i] > vnn) {
                        break;
                }
        }

        value.dptr = (uint8_t *)talloc_realloc(
                rec, value.dptr, uint32_t, num_vnns + 1);
        if (value.dptr == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        value.dsize = talloc_get_size(value.dptr);

        vnns = (uint32_t *)value.dptr;

        memmove(&vnns[i+1], &vnns[i], sizeof(uint32_t) * (num_vnns - i));
        vnns[i] = vnn;

        status = dbwrap_record_store(rec, value, 0);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }
        return NT_STATUS_OK;
}

NTSTATUS notify_remove(struct notify_context *notify, void *private_data)
{
        struct server_id pid;
        struct notify_list *listel;
        struct db_record *notify_rec;
        NTSTATUS status;

        if ((notify == NULL) || (notify->msg == NULL)) {
                return NT_STATUS_NOT_IMPLEMENTED;
        }

        DEBUG(10, ("notify_remove: private_data=%p\n", private_data));

        pid = messaging_server_id(notify->msg);

        for (listel=notify->list;listel;listel=listel->next) {
                if (listel->private_data == private_data) {
                        DLIST_REMOVE(notify->list, listel);
                        break;
                }
        }
        if (listel == NULL) {
                DEBUG(10, ("%p not found\n", private_data));
                return NT_STATUS_NOT_FOUND;
        }
        notify_rec = dbwrap_fetch_locked(notify->db_notify, talloc_tos(),
                                         string_tdb_data(listel->path));
        TALLOC_FREE(listel);
        if (notify_rec == NULL) {
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }
        status = notify_del_entry(notify_rec, &pid, private_data);
        DEBUG(10, ("del_entry returned %s\n", nt_errstr(status)));
        TALLOC_FREE(notify_rec);
        return status;
}

static NTSTATUS notify_del_entry(struct db_record *rec,
                                 const struct server_id *pid,
                                 void *private_data)
{
        TDB_DATA value = dbwrap_record_get_value(rec);
        struct notify_db_entry *entries;
        size_t i, num_entries;
        time_t now;

        DEBUG(10, ("del_entry called for %s %p\n", procid_str_static(pid),
                   private_data));

        if ((value.dsize % sizeof(struct notify_db_entry)) != 0) {
                DEBUG(1, ("Invalid value.dsize = %u\n",
                          (unsigned)value.dsize));
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }
        num_entries = value.dsize / sizeof(struct notify_db_entry);
        entries = (struct notify_db_entry *)value.dptr;

        for (i=0; i<num_entries; i++) {
                struct notify_db_entry *e = &entries[i];

                if (DEBUGLEVEL >= 10) {
                        NDR_PRINT_DEBUG(notify_db_entry, e);
                }

                if (e->private_data != private_data) {
                        continue;
                }
                if (serverid_equal(&e->server, pid)) {
                        break;
                }
        }
        if (i == num_entries) {
                return NT_STATUS_NOT_FOUND;
        }
        entries[i] = entries[num_entries-1];
        value.dsize -= sizeof(struct notify_db_entry);

        if (value.dsize == 0) {
                now = time(NULL);
                value.dptr = (uint8_t *)&now;
                value.dsize = sizeof(now);
        }
        return dbwrap_record_store(rec, value, 0);
}

struct notify_trigger_index_state {
        TALLOC_CTX *mem_ctx;
        uint32_t *vnns;
        uint32_t my_vnn;
        bool found_my_vnn;
};

static void notify_trigger_index_parser(TDB_DATA key, TDB_DATA data,
                                        void *private_data)
{
        struct notify_trigger_index_state *state =
                (struct notify_trigger_index_state *)private_data;
        uint32_t *new_vnns;
        size_t i, num_vnns, num_new_vnns, num_remote_vnns;

        if ((data.dsize % sizeof(uint32_t)) != 0) {
                DEBUG(1, ("Invalid record size in notify index db: %u\n",
                          (unsigned)data.dsize));
                return;
        }
        new_vnns = (uint32_t *)data.dptr;
        num_new_vnns = data.dsize / sizeof(uint32_t);
        num_remote_vnns = num_new_vnns;

        for (i=0; i<num_new_vnns; i++) {
                if (new_vnns[i] == state->my_vnn) {
                        state->found_my_vnn = true;
                        num_remote_vnns -= 1;
                }
        }
        if (num_remote_vnns == 0) {
                return;
        }

        num_vnns = talloc_array_length(state->vnns);
        state->vnns = talloc_realloc(state->mem_ctx, state->vnns, uint32_t,
                                     num_vnns + num_remote_vnns);
        if (state->vnns == NULL) {
                DEBUG(1, ("talloc_realloc failed\n"));
                return;
        }

        for (i=0; i<num_new_vnns; i++) {
                if (new_vnns[i] != state->my_vnn) {
                        state->vnns[num_vnns] = new_vnns[i];
                        num_vnns += 1;
                }
        }
}

static int vnn_cmp(const void *p1, const void *p2)
{
        const uint32_t *vnn1 = (const uint32_t *)p1;
        const uint32_t *vnn2 = (const uint32_t *)p2;

        if (*vnn1 < *vnn2) {
                return -1;
        }
        if (*vnn1 == *vnn2) {
                return 0;
        }
        return 1;
}

static bool notify_push_remote_blob(TALLOC_CTX *mem_ctx, uint32_t action,
                                    uint32_t filter, const char *path,
                                    uint8_t **pblob, size_t *pblob_len)
{
        struct notify_remote_event ev;
        DATA_BLOB data;
        enum ndr_err_code ndr_err;

        ev.action = action;
        ev.filter = filter;
        ev.path = path;

        if (DEBUGLEVEL >= 10) {
                NDR_PRINT_DEBUG(notify_remote_event, &ev);
        }

        ndr_err = ndr_push_struct_blob(
                &data, mem_ctx, &ev,
                (ndr_push_flags_fn_t)ndr_push_notify_remote_event);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                return false;
        }
        *pblob = data.data;
        *pblob_len = data.length;
        return true;
}

static bool notify_pull_remote_blob(TALLOC_CTX *mem_ctx,
                                    const uint8_t *blob, size_t blob_len,
                                    uint32_t *paction, uint32_t *pfilter,
                                    char **path)
{
        struct notify_remote_event *ev;
        enum ndr_err_code ndr_err;
        DATA_BLOB data;
        char *p;

        data.data = discard_const_p(uint8_t, blob);
        data.length = blob_len;

        ev = talloc(mem_ctx, struct notify_remote_event);
        if (ev == NULL) {
                return false;
        }

        ndr_err = ndr_pull_struct_blob(
                &data, ev, ev,
                (ndr_pull_flags_fn_t)ndr_pull_notify_remote_event);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                TALLOC_FREE(ev);
                return false;
        }
        if (DEBUGLEVEL >= 10) {
                NDR_PRINT_DEBUG(notify_remote_event, ev);
        }
        *paction = ev->action;
        *pfilter = ev->filter;
        p = discard_const_p(char, ev->path);
        *path = talloc_move(mem_ctx, &p);

        TALLOC_FREE(ev);
        return true;
}

void notify_trigger(struct notify_context *notify,
                    uint32_t action, uint32_t filter, const char *path)
{
        struct ctdbd_connection *ctdbd_conn;
        struct notify_trigger_index_state idx_state;
        const char *p, *next_p;
        size_t i, num_vnns;
        uint32_t last_vnn;
        uint8_t *remote_blob = NULL;
        size_t remote_blob_len = 0;

        DEBUG(10, ("notify_trigger called action=0x%x, filter=0x%x, "
                   "path=%s\n", (unsigned)action, (unsigned)filter, path));

        /* see if change notify is enabled at all */
        if (notify == NULL) {
                return;
        }

        if (path[0] != '/') {
                /*
                 * The rest of this routine assumes an absolute path.
                 */
                return;
        }

        idx_state.mem_ctx = talloc_tos();
        idx_state.vnns = NULL;
        idx_state.found_my_vnn = false;
        idx_state.my_vnn = get_my_vnn();

        for (p = strchr(path+1, '/'); p != NULL; p = next_p) {
                ptrdiff_t path_len = p - path;
                bool recursive;

                next_p = strchr(p+1, '/');
                recursive = (next_p != NULL);

                dbwrap_parse_record(
                        notify->db_index,
                        make_tdb_data(discard_const_p(uint8_t, path), path_len),
                        notify_trigger_index_parser, &idx_state);

                if (idx_state.found_my_vnn) {
                        notify_trigger_local(notify, action, filter,
                                             path, path_len, recursive);
                        idx_state.found_my_vnn = false;
                }
        }

        if (idx_state.vnns == NULL) {
                goto done;
        }

        ctdbd_conn = messaging_ctdbd_connection();
        if (ctdbd_conn == NULL) {
                goto done;
        }

        num_vnns = talloc_array_length(idx_state.vnns);
        qsort(idx_state.vnns, num_vnns, sizeof(uint32_t), vnn_cmp);

        last_vnn = 0xffffffff;

        if (!notify_push_remote_blob(talloc_tos(), action, filter, path,
                                     &remote_blob, &remote_blob_len)) {
                DEBUG(1, ("notify_push_remote_blob failed\n"));
                goto done;
        }

        for (i=0; i<num_vnns; i++) {
                uint32_t vnn = idx_state.vnns[i];
                NTSTATUS status;

                if (vnn == last_vnn) {
                        continue;
                }

                status = ctdbd_messaging_send_blob(
                        ctdbd_conn, vnn, CTDB_SRVID_SAMBA_NOTIFY_PROXY,
                        remote_blob, remote_blob_len);
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(10, ("ctdbd_messaging_send_blob to vnn %d "
                                   "returned %s, ignoring\n", (int)vnn,
                                   nt_errstr(status)));
                }

                last_vnn = vnn;
        }

done:
        TALLOC_FREE(remote_blob);
        TALLOC_FREE(idx_state.vnns);
}

static void notify_trigger_local(struct notify_context *notify,
                                 uint32_t action, uint32_t filter,
                                 const char *path, size_t path_len,
                                 bool recursive)
{
        TDB_DATA data;
        struct notify_db_entry *entries;
        size_t i, num_entries;
        NTSTATUS status;

        DEBUG(10, ("notify_trigger_local called for %*s, path_len=%d, "
                   "filter=%d\n", (int)path_len, path, (int)path_len,
                   (int)filter));

        status = dbwrap_fetch(
                notify->db_notify, talloc_tos(),
                make_tdb_data(discard_const_p(uint8_t, path), path_len), &data);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10, ("dbwrap_fetch returned %s\n",
                           nt_errstr(status)));
                return;
        }
        if (data.dsize == sizeof(time_t)) {
                DEBUG(10, ("Got deleted record\n"));
                goto done;
        }
        if ((data.dsize % sizeof(struct notify_db_entry)) != 0) {
                DEBUG(1, ("Invalid data.dsize = %u\n",
                          (unsigned)data.dsize));
                goto done;
        }

        entries = (struct notify_db_entry *)data.dptr;
        num_entries = data.dsize / sizeof(struct notify_db_entry);

        DEBUG(10, ("recursive = %s pathlen=%d (%c)\n",
                   recursive ? "true" : "false", (int)path_len,
                   path[path_len]));

        for (i=0; i<num_entries; i++) {
                struct notify_db_entry *e = &entries[i];
                uint32_t e_filter;

                if (DEBUGLEVEL >= 10) {
                        NDR_PRINT_DEBUG(notify_db_entry, e);
                }

                e_filter = recursive ? e->subdir_filter : e->filter;

                if ((filter & e_filter) == 0) {
                        continue;
                }

                if (!procid_is_local(&e->server)) {
                        DEBUG(1, ("internal error: Non-local pid %s in "
                                  "notify.tdb\n",
                                  procid_str_static(&e->server)));
                        continue;
                }

                status = notify_send(notify, &e->server, path + path_len + 1,
                                     action, e->private_data);
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(10, ("notify_send returned %s\n",
                                   nt_errstr(status)));
                }
        }

done:
        TALLOC_FREE(data.dptr);
}

struct notify_msg {
        struct timespec when;
        void *private_data;
        uint32_t action;
        char path[1];
};

static NTSTATUS notify_send(struct notify_context *notify,
                            struct server_id *pid,
                            const char *path, uint32_t action,
                            void *private_data)
{
        struct notify_msg m = {};
        struct iovec iov[2];

        m.when = timespec_current();
        m.private_data = private_data;
        m.action = action;

        iov[0].iov_base = &m;
        iov[0].iov_len = offsetof(struct notify_msg, path);
        iov[1].iov_base = discard_const_p(char, path);
        iov[1].iov_len = strlen(path)+1;

        return messaging_send_iov(notify->msg, *pid, MSG_PVFS_NOTIFY,
                                  iov, ARRAY_SIZE(iov));
}

static void notify_handler(struct messaging_context *msg_ctx,
                           void *private_data, uint32_t msg_type,
                           struct server_id server_id, DATA_BLOB *data)
{
        struct notify_context *notify = talloc_get_type_abort(
                private_data, struct notify_context);
        struct notify_msg *m;
        struct notify_event e;
        struct notify_list *listel;

        if (data->length == 0) {
                DEBUG(1, ("%s: Got 0-sized MSG_PVFS_NOTIFY msg\n", __func__));
                return;
        }
        if (data->data[data->length-1] != 0) {
                DEBUG(1, ("%s: MSG_PVFS_NOTIFY path not 0-terminated\n",
                          __func__));
                return;
        }

        m = (struct notify_msg *)data->data;
        e.action = m->action;
        e.path = m->path;
        e.private_data = m->private_data;

        for (listel=notify->list;listel;listel=listel->next) {
                if (listel->private_data == m->private_data) {
                        listel->callback(listel->private_data, m->when, &e);
                        break;
                }
        }
}

struct notify_walk_idx_state {
        void (*fn)(const char *path,
                   uint32_t *vnns, size_t num_vnns,
                   void *private_data);
        void *private_data;
};

static int notify_walk_idx_fn(struct db_record *rec, void *private_data)
{
        struct notify_walk_idx_state *state =
                (struct notify_walk_idx_state *)private_data;
        TDB_DATA key, value;
        char *path;

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

        if ((value.dsize % sizeof(uint32_t)) != 0) {
                DEBUG(1, ("invalid value size in notify index db: %u\n",
                          (unsigned)(value.dsize)));
                return 0;
        }

        path = talloc_strndup(talloc_tos(), (char *)key.dptr, key.dsize);
        if (path == NULL) {
                DEBUG(1, ("talloc_strndup failed\n"));
                return 0;
        }
        state->fn(path, (uint32_t *)value.dptr, value.dsize/sizeof(uint32_t),
                  state->private_data);
        TALLOC_FREE(path);
        return 0;
}

void notify_walk_idx(struct notify_context *notify,
                     void (*fn)(const char *path,
                                uint32_t *vnns, size_t num_vnns,
                                void *private_data),
                     void *private_data)
{
        struct notify_walk_idx_state state;
        state.fn = fn;
        state.private_data = private_data;
        dbwrap_traverse_read(notify->db_index, notify_walk_idx_fn, &state,
                             NULL);
}

struct notify_walk_state {
        void (*fn)(const char *path,
                   struct notify_db_entry *entries, size_t num_entries,
                   time_t deleted_time, void *private_data);
        void *private_data;
};

static int notify_walk_fn(struct db_record *rec, void *private_data)
{
        struct notify_walk_state *state =
                (struct notify_walk_state *)private_data;
        TDB_DATA key, value;
        struct notify_db_entry *entries;
        size_t num_entries;
        time_t deleted_time;
        char *path;

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

        if (value.dsize == sizeof(deleted_time)) {
                memcpy(&deleted_time, value.dptr, sizeof(deleted_time));
                entries = NULL;
                num_entries = 0;
        } else {
                if ((value.dsize % sizeof(struct notify_db_entry)) != 0) {
                        DEBUG(1, ("invalid value size in notify db: %u\n",
                                  (unsigned)(value.dsize)));
                        return 0;
                }
                entries = (struct notify_db_entry *)value.dptr;
                num_entries = value.dsize / sizeof(struct notify_db_entry);
                deleted_time = 0;
        }

        path = talloc_strndup(talloc_tos(), (char *)key.dptr, key.dsize);
        if (path == NULL) {
                DEBUG(1, ("talloc_strndup failed\n"));
                return 0;
        }
        state->fn(path, entries, num_entries, deleted_time,
                  state->private_data);
        TALLOC_FREE(path);
        return 0;
}

void notify_walk(struct notify_context *notify,
                 void (*fn)(const char *path,
                            struct notify_db_entry *entries,
                            size_t num_entries,
                            time_t deleted_time, void *private_data),
                 void *private_data)
{
        struct notify_walk_state state;
        state.fn = fn;
        state.private_data = private_data;
        dbwrap_traverse_read(notify->db_notify, notify_walk_fn, &state,
                             NULL);
}

struct notify_cleanup_state {
        TALLOC_CTX *mem_ctx;
        time_t delete_before;
        ssize_t array_size;
        uint32_t num_paths;
        char **paths;
};

static void notify_cleanup_collect(
        const char *path, struct notify_db_entry *entries, size_t num_entries,
        time_t deleted_time, void *private_data)
{
        struct notify_cleanup_state *state =
                (struct notify_cleanup_state *)private_data;
        char *p;

        if (num_entries != 0) {
                return;
        }
        if (deleted_time >= state->delete_before) {
                return;
        }

        p = talloc_strdup(state->mem_ctx, path);
        if (p == NULL) {
                DEBUG(1, ("talloc_strdup failed\n"));
                return;
        }
        add_to_large_array(state->mem_ctx, sizeof(p), (void *)&p,
                           &state->paths, &state->num_paths,
                           &state->array_size);
        if (state->array_size == -1) {
                TALLOC_FREE(p);
        }
}

static bool notify_cleanup_path(struct notify_context *notify,
                              const char *path, time_t delete_before);

void notify_cleanup(struct notify_context *notify)
{
        struct notify_cleanup_state state;
        uint32_t failure_pool;

        ZERO_STRUCT(state);
        state.mem_ctx = talloc_stackframe();

        state.delete_before = time(NULL)
                - lp_parm_int(-1, "smbd", "notify cleanup interval", 60);

        notify_walk(notify, notify_cleanup_collect, &state);

        failure_pool = state.num_paths;

        while (state.num_paths != 0) {
                size_t idx;

                /*
                 * This loop is designed to be as kind as possible to
                 * ctdb. ctdb does not like it if many smbds hammer on a
                 * single record. If on many nodes the cleanup process starts
                 * running, it can happen that all of them need to clean up
                 * records in the same order. This would generate a ctdb
                 * migrate storm on these records. Randomizing the load across
                 * multiple records reduces the load on the individual record.
                 */

                generate_random_buffer((uint8_t *)&idx, sizeof(idx));
                idx = idx % state.num_paths;

                if (!notify_cleanup_path(notify, state.paths[idx],
                                         state.delete_before)) {
                        /*
                         * notify_cleanup_path failed, the most likely reason
                         * is that dbwrap_try_fetch_locked failed due to
                         * contention. We allow one failed attempt per deleted
                         * path on average before we give up.
                         */
                        failure_pool -= 1;
                        if (failure_pool == 0) {
                                /*
                                 * Too many failures. We will come back here,
                                 * maybe next time there is less contention.
                                 */
                                break;
                        }
                }

                TALLOC_FREE(state.paths[idx]);
                state.paths[idx] = state.paths[state.num_paths-1];
                state.num_paths -= 1;
        }
        TALLOC_FREE(state.mem_ctx);
}

static bool notify_cleanup_path(struct notify_context *notify,
                                const char *path, time_t delete_before)
{
        struct db_record *notify_rec = NULL;
        struct db_record *idx_rec = NULL;
        TDB_DATA key = string_tdb_data(path);
        TDB_DATA value;
        time_t deleted;
        NTSTATUS status;

        notify_rec = dbwrap_fetch_locked(notify->db_notify, talloc_tos(), key);
        if (notify_rec == NULL) {
                DEBUG(10, ("Could not fetch notify_rec\n"));
                return false;
        }
        value = dbwrap_record_get_value(notify_rec);

        if (value.dsize != sizeof(deleted)) {
                DEBUG(10, ("record %s has been re-used\n", path));
                goto done;
        }
        memcpy(&deleted, value.dptr, sizeof(deleted));

        if (deleted >= delete_before) {
                DEBUG(10, ("record %s too young\n", path));
                goto done;
        }

        /*
         * Be kind to ctdb and only try one dmaster migration at most.
         */
        idx_rec = dbwrap_try_fetch_locked(notify->db_index, talloc_tos(), key);
        if (idx_rec == NULL) {
                DEBUG(10, ("Could not fetch idx_rec\n"));
                goto done;
        }

        status = dbwrap_record_delete(notify_rec);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10, ("Could not delete notify_rec: %s\n",
                           nt_errstr(status)));
        }

        status = notify_del_idx(idx_rec, get_my_vnn());
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10, ("Could not delete idx_rec: %s\n",
                           nt_errstr(status)));
        }

done:
        TALLOC_FREE(idx_rec);
        TALLOC_FREE(notify_rec);
        return true;
}

static NTSTATUS notify_del_idx(struct db_record *rec, uint32_t vnn)
{
        TDB_DATA value = dbwrap_record_get_value(rec);
        uint32_t *vnns;
        size_t i, num_vnns;

        if ((value.dsize % sizeof(uint32_t)) != 0) {
                DEBUG(1, ("Invalid value.dsize = %u\n",
                          (unsigned)value.dsize));
                return NT_STATUS_INTERNAL_DB_CORRUPTION;
        }
        num_vnns = value.dsize / sizeof(uint32_t);
        vnns = (uint32_t *)value.dptr;

        for (i=0; i<num_vnns; i++) {
                if (vnns[i] == vnn) {
                        break;
                }
        }

        if (i == num_vnns) {
                /*
                 * Not found. Should not happen, but okay...
                 */
                return NT_STATUS_OK;
        }

        memmove(&vnns[i], &vnns[i+1], sizeof(uint32_t) * (num_vnns - i - 1));
        value.dsize -= sizeof(uint32_t);

        if (value.dsize == 0) {
                return dbwrap_record_delete(rec);
        }
        return dbwrap_record_store(rec, value, 0);
}

struct notify_cluster_proxy_state {
        struct tevent_context *ev;
        struct notify_context *notify;
        struct ctdb_msg_channel *chan;
};

static void notify_cluster_proxy_got_chan(struct tevent_req *subreq);
static void notify_cluster_proxy_got_msg(struct tevent_req *subreq);
static void notify_cluster_proxy_trigger(struct notify_context *notify,
                                         uint32_t action, uint32_t filter,
                                         char *path);

struct tevent_req *notify_cluster_proxy_send(
        TALLOC_CTX *mem_ctx, struct tevent_context *ev,
        struct notify_context *notify)
{
        struct tevent_req *req, *subreq;
        struct notify_cluster_proxy_state *state;

        req = tevent_req_create(mem_ctx, &state,
                                struct notify_cluster_proxy_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->notify = notify;

        subreq = ctdb_msg_channel_init_send(
                state, state->ev,  lp_ctdbd_socket(),
                CTDB_SRVID_SAMBA_NOTIFY_PROXY);
        if (tevent_req_nomem(subreq, req)) {
                return tevent_req_post(req, ev);
        }
        tevent_req_set_callback(subreq, notify_cluster_proxy_got_chan, req);
        return req;
}

static void notify_cluster_proxy_got_chan(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct notify_cluster_proxy_state *state = tevent_req_data(
                req, struct notify_cluster_proxy_state);
        int ret;

        ret = ctdb_msg_channel_init_recv(subreq, state, &state->chan);
        TALLOC_FREE(subreq);
        if (ret != 0) {
                tevent_req_error(req, ret);
                return;
        }
        subreq = ctdb_msg_read_send(state, state->ev, state->chan);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, notify_cluster_proxy_got_msg, req);
}

static void notify_cluster_proxy_got_msg(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct notify_cluster_proxy_state *state = tevent_req_data(
                req, struct notify_cluster_proxy_state);
        uint8_t *msg;
        size_t msg_len;
        uint32_t action, filter;
        char *path;
        int ret;
        bool res;

        ret = ctdb_msg_read_recv(subreq, talloc_tos(), &msg, &msg_len);
        TALLOC_FREE(subreq);
        if (ret != 0) {
                tevent_req_error(req, ret);
                return;
        }

        res = notify_pull_remote_blob(talloc_tos(), msg, msg_len,
                                      &action, &filter, &path);
        TALLOC_FREE(msg);
        if (!res) {
                tevent_req_error(req, EIO);
                return;
        }
        notify_cluster_proxy_trigger(state->notify, action, filter, path);
        TALLOC_FREE(path);

        subreq = ctdb_msg_read_send(state, state->ev, state->chan);
        if (tevent_req_nomem(subreq, req)) {
                return;
        }
        tevent_req_set_callback(subreq, notify_cluster_proxy_got_msg, req);
}

static void notify_cluster_proxy_trigger(struct notify_context *notify,
                                         uint32_t action, uint32_t filter,
                                         char *path)
{
        const char *p, *next_p;

        for (p = path; p != NULL; p = next_p) {
                ptrdiff_t path_len = p - path;
                bool recursive;

                next_p = strchr(p+1, '/');
                recursive = (next_p != NULL);

                notify_trigger_local(notify, action, filter,
                                     path, path_len, recursive);
        }
}

int notify_cluster_proxy_recv(struct tevent_req *req)
{
        int err;

        if (tevent_req_is_unix_error(req, &err)) {
                return err;
        }
        return 0;
}