ndr: Pass down string_flags in ndr_pull_ntprinting_printer().

[Samba.git] / source3 / modules / onefs_notify.c

/*
 * Unix SMB/CIFS implementation.
 *
 * Support for change notify using OneFS's file event notification system
 *
 * Copyright (C) Andrew Tridgell, 2006
 * Copyright (C) Steven Danneman, 2008
 *
 * 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/>.
 */

/* Implement handling of change notify requests on files and directories using
 * Isilon OneFS's "ifs event" file notification system.
 *
 * The structure of this file is based off the implementation of change notify
 * using the inotify system calls in smbd/notify_inotify.c */

/* TODO: We could reduce the number of file descriptors used by merging
 * multiple watch requests on the same directory into the same
 * onefs_notify_watch_context.  To do this we'd need mux/demux routines that
 * when receiving an event on that watch context would check it against the
 * CompletionFilter and WatchTree of open SMB requests, and return notify
 * events back to the proper SMB requests */

#include "includes.h"
#include "smbd/smbd.h"
#include "onefs.h"

#include <ifs/ifs_types.h>
#include <ifs/ifs_syscalls.h>
#include <isi_util/syscalls.h>

#include <sys/event.h>

#define ONEFS_IFS_EVENT_MAX_NUM 8
#define ONEFS_IFS_EVENT_MAX_BYTES (ONEFS_IFS_EVENT_MAX_NUM * \
                                   sizeof(struct ifs_event))

struct onefs_notify_watch_context {
        struct sys_notify_context *ctx;
        int watch_fd;
        ino_t watch_lin;
        const char *path;
        int ifs_event_fd;
        uint32_t ifs_filter; /* the ifs event mask */
        uint32_t smb_filter; /* the windows completion filter */
        void (*callback)(struct sys_notify_context *ctx,
                         void *private_data,
                         struct notify_event *ev);
        void *private_data;
};

/**
 * Conversion map from a SMB completion filter to an IFS event mask.
 */
static const struct {
        uint32_t smb_filter;
        uint32_t ifs_filter;
} onefs_notify_conv[] = {
        {FILE_NOTIFY_CHANGE_FILE_NAME,
            NOTE_CREATE | NOTE_DELETE | NOTE_RENAME_FROM | NOTE_RENAME_TO},
        {FILE_NOTIFY_CHANGE_DIR_NAME,
            NOTE_CREATE | NOTE_DELETE | NOTE_RENAME_FROM | NOTE_RENAME_TO},
        {FILE_NOTIFY_CHANGE_ATTRIBUTES,
            NOTE_CREATE | NOTE_DELETE | NOTE_RENAME_FROM | NOTE_RENAME_TO |
            NOTE_ATTRIB},
        {FILE_NOTIFY_CHANGE_SIZE,
            NOTE_SIZE | NOTE_EXTEND},
        {FILE_NOTIFY_CHANGE_LAST_WRITE,
            NOTE_WRITE | NOTE_ATTRIB},
        /* OneFS doesn't set atime by default, but we can somewhat fake it by
         * notifying for other events that imply ACCESS */
        {FILE_NOTIFY_CHANGE_LAST_ACCESS,
            NOTE_WRITE | NOTE_ATTRIB},
        /* We don't have an ifs_event for the setting of create time, but we
         * can fake by notifying when a "new" file is created via rename */
        {FILE_NOTIFY_CHANGE_CREATION,
            NOTE_RENAME_TO},
        {FILE_NOTIFY_CHANGE_SECURITY,
            NOTE_SECURITY},
        /* Unsupported bits
        FILE_NOTIFY_CHANGE_EA            (no EAs in OneFS)
        FILE_NOTIFY_CHANGE_STREAM_NAME   (no ifs_event equivalent)
        FILE_NOTIFY_CHANGE_STREAM_SIZE   (no ifs_event equivalent)
        FILE_NOTIFY_CHANGE_STREAM_WRITE  (no ifs_event equivalent) */
};

#define ONEFS_NOTIFY_UNSUPPORTED  (FILE_NOTIFY_CHANGE_LAST_ACCESS | \
                                   FILE_NOTIFY_CHANGE_CREATION    | \
                                   FILE_NOTIFY_CHANGE_EA          | \
                                   FILE_NOTIFY_CHANGE_STREAM_NAME | \
                                   FILE_NOTIFY_CHANGE_STREAM_SIZE | \
                                   FILE_NOTIFY_CHANGE_STREAM_WRITE)

/**
 * Convert Windows/SMB filter/flags to IFS event filter.
 *
 * @param[in] smb_filter Windows Completion Filter sent in the SMB
 *
 * @return ifs event filter mask
 */
static uint32_t
onefs_notify_smb_filter_to_ifs_filter(uint32_t smb_filter)
{
        int i;
        uint32_t ifs_filter = 0x0;

        for (i=0;i<ARRAY_SIZE(onefs_notify_conv);i++) {
                if (onefs_notify_conv[i].smb_filter & smb_filter) {
                        ifs_filter |= onefs_notify_conv[i].ifs_filter;
                }
        }

        return ifs_filter;
}

/**
 * Convert IFS filter/flags to a Windows notify action.
 *
 * Returns Win notification actions, types (1-5).
 *
 * @param[in] smb_filter Windows Completion Filter sent in the SMB
 * @param[in] ifs_filter Returned from the kernel in the ifs_event
 *
 * @return 0 if there are no more relevant flags.
 */
static int
onefs_notify_ifs_filter_to_smb_action(uint32_t smb_filter, uint32_t ifs_filter)
{
        /* Handle Windows special cases, before modifying events bitmask */

        /* Special case 1: win32api->MoveFile needs to send a modified
         * notification on the new file, if smb_filter == ATTRIBUTES.
         * Here we handle the case where two separate ATTR & NAME notifications
         * have been registered.  We handle the case where both bits are set in
         * the same registration in onefs_notify_dispatch() */
        if ((smb_filter & FILE_NOTIFY_CHANGE_ATTRIBUTES) &&
                !(smb_filter & FILE_NOTIFY_CHANGE_FILE_NAME) &&
                (ifs_filter & NOTE_FILE) && (ifs_filter & NOTE_RENAME_TO))
        {
                return NOTIFY_ACTION_MODIFIED;
        }

        /* Special case 2: Writes need to send a modified
         * notification on the file, if smb_filter = ATTRIBUTES. */
        if ((smb_filter & FILE_NOTIFY_CHANGE_ATTRIBUTES) &&
                (ifs_filter & NOTE_FILE) && (ifs_filter & NOTE_WRITE))
        {
                return NOTIFY_ACTION_MODIFIED;
        }

        /* Loop because some events may be filtered out. Eventually all
         * relevant events will be taken care of and returned. */
        while (1) {
                if (ifs_filter & NOTE_CREATE) {
                        ifs_filter &= ~NOTE_CREATE;
                        if ((smb_filter & FILE_NOTIFY_CHANGE_FILE_NAME) &&
                                (ifs_filter & NOTE_FILE))
                                return NOTIFY_ACTION_ADDED;
                        if ((smb_filter & FILE_NOTIFY_CHANGE_DIR_NAME) &&
                                (ifs_filter & NOTE_DIRECTORY))
                                return NOTIFY_ACTION_ADDED;
                }
                else if (ifs_filter & NOTE_DELETE) {
                        ifs_filter &= ~NOTE_DELETE;
                        if ((smb_filter & FILE_NOTIFY_CHANGE_FILE_NAME) &&
                                (ifs_filter & NOTE_FILE))
                                return NOTIFY_ACTION_REMOVED;
                        if ((smb_filter & FILE_NOTIFY_CHANGE_DIR_NAME) &&
                                (ifs_filter & NOTE_DIRECTORY))
                                return NOTIFY_ACTION_REMOVED;
                }
                else if (ifs_filter & NOTE_WRITE) {
                        ifs_filter &= ~NOTE_WRITE;
                        if ((smb_filter & FILE_NOTIFY_CHANGE_LAST_WRITE) ||
                                (smb_filter & FILE_NOTIFY_CHANGE_LAST_ACCESS))
                                return NOTIFY_ACTION_MODIFIED;
                }
                else if ((ifs_filter & NOTE_SIZE) || (ifs_filter & NOTE_EXTEND)) {
                        ifs_filter &= ~NOTE_SIZE;
                        ifs_filter &= ~NOTE_EXTEND;

                        /* TODO: Do something on NOTE_DIR? */
                        if ((smb_filter & FILE_NOTIFY_CHANGE_SIZE) &&
                            (ifs_filter & NOTE_FILE))
                                return NOTIFY_ACTION_MODIFIED;
                }
                else if (ifs_filter & NOTE_ATTRIB) {
                        ifs_filter &= ~NOTE_ATTRIB;
                        /* NOTE_ATTRIB needs to be converted to a
                         * LAST_WRITE as well, because we need to send
                         * LAST_WRITE when the mtime changes. Looking into
                         * better alternatives as this causes extra LAST_WRITE
                         * notifications. We also return LAST_ACCESS as a
                         * modification to attribs implies this. */
                        if ((smb_filter & FILE_NOTIFY_CHANGE_ATTRIBUTES) ||
                                (smb_filter & FILE_NOTIFY_CHANGE_LAST_WRITE) ||
                                (smb_filter & FILE_NOTIFY_CHANGE_LAST_ACCESS))
                                return NOTIFY_ACTION_MODIFIED;
                }
                else if (ifs_filter & NOTE_LINK) {
                        ifs_filter &= ~NOTE_LINK;
                        /* NOTE_LINK will send out NO notifications */
                }
                else if (ifs_filter & NOTE_REVOKE) {
                        ifs_filter &= ~NOTE_REVOKE;
                        /* NOTE_REVOKE will send out NO notifications */
                }
                else if (ifs_filter & NOTE_RENAME_FROM)  {
                        ifs_filter &= ~NOTE_RENAME_FROM;

                        if (((smb_filter & FILE_NOTIFY_CHANGE_FILE_NAME) &&
                                 (ifs_filter & NOTE_FILE)) ||
                                ((smb_filter & FILE_NOTIFY_CHANGE_DIR_NAME) &&
                                 (ifs_filter & NOTE_DIRECTORY))) {
                                /* Check if this is a RENAME, not a MOVE */
                                if (ifs_filter & NOTE_RENAME_SAMEDIR) {
                                        /* Remove the NOTE_RENAME_SAMEDIR, IFF
                                         * RENAME_TO is not in this event */
                                        if (!(ifs_filter & NOTE_RENAME_TO))
                                                ifs_filter &=
                                                    ~NOTE_RENAME_SAMEDIR;
                                        return NOTIFY_ACTION_OLD_NAME;
                                }
                                return NOTIFY_ACTION_REMOVED;
                        }
                }
                else if (ifs_filter & NOTE_RENAME_TO) {
                        ifs_filter &= ~NOTE_RENAME_TO;

                        if (((smb_filter & FILE_NOTIFY_CHANGE_FILE_NAME) &&
                                 (ifs_filter & NOTE_FILE)) ||
                                ((smb_filter & FILE_NOTIFY_CHANGE_DIR_NAME) &&
                                 (ifs_filter & NOTE_DIRECTORY))) {
                                /* Check if this is a RENAME, not a MOVE */
                                if (ifs_filter & NOTE_RENAME_SAMEDIR) {
                                        /* Remove the NOTE_RENAME_SAMEDIR, IFF
                                         * RENAME_FROM is not in this event */
                                        if (!(ifs_filter & NOTE_RENAME_FROM))
                                                ifs_filter &=
                                                    ~NOTE_RENAME_SAMEDIR;
                                        return NOTIFY_ACTION_NEW_NAME;
                                }
                                return NOTIFY_ACTION_ADDED;
                        }
                        /* RAW-NOTIFY shows us that a rename triggers a
                         * creation time change */
                        if ((smb_filter & FILE_NOTIFY_CHANGE_CREATION) &&
                                (ifs_filter & NOTE_FILE))
                                return NOTIFY_ACTION_MODIFIED;
                }
                else if (ifs_filter & NOTE_SECURITY) {
                        ifs_filter &= ~NOTE_SECURITY;

                        if (smb_filter & FILE_NOTIFY_CHANGE_SECURITY)
                                return NOTIFY_ACTION_MODIFIED;
                } else {
                        /* No relevant flags found */
                        return 0;
                }
        }
}

/**
 * Retrieve a directory path of a changed file, relative to the watched dir
 *
 * @param[in] wc watch context for the returned event
 * @param[in] e ifs_event notification returned from the kernel
 * @param[out] path name relative to the watched dir. This is talloced
 *                  off of wc and needs to be freed by the caller.
 *
 * @return true on success
 *
 * TODO: This function currently doesn't handle path names with multiple
 * encodings.  enc_get_lin_path() should be used in the future to convert
 * each path segment's encoding to UTF-8
 */
static bool
get_ifs_event_path(struct onefs_notify_watch_context *wc, struct ifs_event *e,
                   char **path)
{
        char *path_buf = NULL;
        size_t pathlen = 0;
        int error = 0;

        SMB_ASSERT(path);

        /* Lookup the path from watch_dir through our parent dir */
        if (e->namelen > 0) {
                error = lin_get_path(wc->watch_lin,
                                     e->parent_lin,
                                     HEAD_SNAPID,
                                     e->parent_parent_lin,
                                     e->parent_name_hash,
                                     &pathlen, &path_buf);
                if (!error) {
                        /* Only add slash if a path exists in path_buf from
                         * lin_get_path call. Windows does not expect a
                         * leading '/' */
                        if (pathlen > 0)
                                *path = talloc_asprintf(wc, "%s/%s",
                                                        path_buf, e->name);
                        else
                                *path = talloc_asprintf(wc, "%s", e->name);
                        SAFE_FREE(path_buf);
                }
        }

        /* If ifs_event didn't return a name, or we errored out of our intial
         * path lookup, try again using the lin of the changed file */
        if (!(*path)) {
                error = lin_get_path(wc->watch_lin,
                                     e->lin,
                                     HEAD_SNAPID,
                                     e->parent_lin,
                                     e->name_hash,
                                     &pathlen, &path_buf);
                if (error) {
                        /* It's possible that both the lin and the parent lin
                         * are invalid (or not given) -- we will skip these
                         * events. */
                        DEBUG(3,("Path lookup failed. LINS are invalid: "
                                 "e->lin: 0x%llu, e->parent_lin: 0x%llu, "
                                 "e->parent_parent_lin: 0x%llu\n",
                                 e->lin, e->parent_lin, e->parent_parent_lin));
                        SAFE_FREE(path_buf);
                        return false;
                } else {
                        *path = talloc_asprintf(wc, "%s", path_buf);
                        DEBUG(5, ("Using path from event LIN = %s\n",
                            path_buf));
                        SAFE_FREE(path_buf);
                }
        }

        /* Replacement of UNIX slashes with WIN slashes is handled at a
         * higher layer. */

        return true;
}

/**
 * Dispatch one OneFS notify event to the general Samba code
 *
 * @param[in] wc watch context for the returned event
 * @param[in] e event returned from the kernel
 *
 * @return nothing
 */
static void
onefs_notify_dispatch(struct onefs_notify_watch_context *wc,
                      struct ifs_event *e)
{
        char *path = NULL;
        struct notify_event ne;

        DEBUG(5, ("Retrieved ifs event from kernel: lin=%#llx, ifs_events=%#x, "
                 "parent_lin=%#llx, namelen=%d, name=\"%s\"\n",
                 e->lin, e->events, e->parent_lin, e->namelen, e->name));

        /* Check validity of event returned from kernel */
        if (e->lin == 0) {
                /* The lin == 0 specifies 1 of 2 cases:
                 * 1) We are out of events. The kernel has a limited
                 *    amount (somewhere near 90000)
                 * 2) Split nodes have merged back and had data written
                 *    to them -- thus we've missed some of those events.  */
                DEBUG(3, ("We've missed some kernel ifs events!\n"));

                /* Alert higher level to the problem so it returns catch-all
                 * response to the client */
                ne.path = NULL;
                ne.action = 0;
                wc->callback(wc->ctx, wc->private_data, &ne);
        }

        if (e->lin == wc->watch_lin) {
                /* Windows doesn't report notifications on root
                 * watched directory */
                /* TODO: This should be abstracted out to the general layer
                 * instead of being handled in every notify provider */
                DEBUG(5, ("Skipping notification on root of the watched "
                         "path.\n"));
                return;
        }

        /* Retrieve the full path for the ifs event name */
        if(!get_ifs_event_path(wc, e, &path)) {
                DEBUG(3, ("Failed to convert the ifs_event lins to a path. "
                         "Skipping this event\n"));
                return;
        }

        if (!strncmp(path, ".ifsvar", 7)) {
                /* Skip notifications on file if its in ifs configuration
                 * directory */
                goto clean;
        }

        ne.path = path;

        /* Convert ifs event mask to an smb action mask */
        ne.action = onefs_notify_ifs_filter_to_smb_action(wc->smb_filter,
                                                          e->events);

        DEBUG(5, ("Converted smb_filter=%#x, ifs_events=%#x, to "
                  "ne.action = %d, for ne.path = %s\n",
                  wc->smb_filter, e->events, ne.action, ne.path));

        if (!ne.action)
                goto clean;

        /* Return notify_event to higher level */
        wc->callback(wc->ctx, wc->private_data, &ne);

        /* SMB expects a file rename/move to generate three actions, a
         * rename_from/delete on the from file, a rename_to/create on the to
         * file, and a modify for the rename_to file. If we have two separate
         * notifications registered for ATTRIBUTES and FILENAME, this case will
         * be handled by separate ifs_events in
         * onefs_notify_ifs_filter_to_smb_action(). If both bits are registered
         * in the same notification, we must send an extra MODIFIED action
         * here. */
        if ((wc->smb_filter & FILE_NOTIFY_CHANGE_ATTRIBUTES) &&
            (wc->smb_filter & FILE_NOTIFY_CHANGE_FILE_NAME) &&
            (e->events & NOTE_FILE) && (e->events & NOTE_RENAME_TO))
        {
                ne.action = NOTIFY_ACTION_MODIFIED;
                wc->callback(wc->ctx, wc->private_data, &ne);
        }

        /* FALLTHROUGH */
clean:
        talloc_free(path);
        return;
}

/**
 * Callback when the kernel has some events for us
 *
 * Read events off ifs event fd and pass them to our dispatch function
 *
 * @param ev context of all tevents registered in the smbd
 * @param fde tevent struct specific to one ifs event channel
 * @param flags tevent flags passed when we added our ifs event channel fd to
 *              the main loop
 * @param private_data onefs_notify_watch_context specific to this ifs event
 *                     channel
 *
 * @return nothing
 */
static void
onefs_notify_handler(struct event_context *ev,
                     struct fd_event *fde,
                     uint16_t flags,
                     void *private_data)
{
        struct onefs_notify_watch_context *wc = NULL;
        struct ifs_event ifs_events[ONEFS_IFS_EVENT_MAX_NUM];
        ssize_t nread = 0;
        int count = 0;
        int i = 0;

        wc = talloc_get_type(private_data, struct onefs_notify_watch_context);

        /* Read as many ifs events from the notify channel as we can */
        nread = sys_read(wc->ifs_event_fd, &ifs_events,
                         ONEFS_IFS_EVENT_MAX_BYTES);
        if (nread == 0) {
                DEBUG(0,("No data found while reading ifs event fd?!\n"));
                return;
        }
        if (nread < 0) {
                DEBUG(0,("Failed to read ifs event data: %s\n",
                        strerror(errno)));
                return;
        }

        count = nread / sizeof(struct ifs_event);

        DEBUG(5, ("Got %d notification events in %d bytes.\n", count, nread));

        /* Dispatch ifs_events one-at-a-time to higher level */
        for (i=0; i < count; i++) {
                onefs_notify_dispatch(wc, &ifs_events[i]);
        }
}

/**
 * Destroy the ifs event channel
 *
 * This is called from talloc_free() when the generic Samba notify layer frees
 * the onefs_notify_watch_context.
 *
 * @param[in] wc pointer to watch context which is being destroyed
 *
 * return 0 on success
*/
static int
onefs_watch_destructor(struct onefs_notify_watch_context *wc)
{
        /* The ifs_event_fd will re de-registered from the event loop by
         * another destructor triggered from the freeing of this wc */
        close(wc->ifs_event_fd);
        return 0;
}

/**
 * Register a single change notify watch request.
 *
 * Open an event listener on a directory to watch for modifications. This
 * channel is closed by a destructor when the caller calls talloc_free()
 * on *handle.
 *
 * @param[in] vfs_handle handle given to most VFS operations
 * @param[in] ctx context (conn and tevent) for this connection
 * @param[in] e filter and path of client's notify request
 * @param[in] callback function to call when file notification event is received
 *                     from the kernel, passing that event up to Samba's
 *                     generalized change notify layer
 * @param[in] private_data opaque data given to us by the general change notify
 *                         layer which must be returned in the callback function
 * @param[out] handle_p handle returned to generalized change notify layer used
 *                      to close the event channel when notification is
 *                      cancelled
 *
 * @return NT_STATUS_OK unless error
 */
NTSTATUS
onefs_notify_watch(vfs_handle_struct *vfs_handle,
                   struct sys_notify_context *ctx,
                   struct notify_entry *e,
                   void (*callback)(struct sys_notify_context *ctx,
                                    void *private_data,
                                    struct notify_event *ev),
                   void *private_data,
                   void *handle_p)
{
        int ifs_event_fd = -1;
        uint32_t ifs_filter = 0;
        uint32_t smb_filter = e->filter;
        bool watch_tree = !!e->subdir_filter;
        struct onefs_notify_watch_context *wc = NULL;
        void **handle = (void **)handle_p;
        SMB_STRUCT_STAT sbuf;
        NTSTATUS status = NT_STATUS_UNSUCCESSFUL;

        /* Fallback to default Samba implementation if kernel CN is disabled */
        if (!lp_kernel_change_notify(vfs_handle->conn->params)) {
                (*handle) = NULL;
                return NT_STATUS_OK;
        }

        /* The OneFS open path should always give us a valid fd on a directory*/
        SMB_ASSERT(e->dir_fd >= 0);

        /* Always set e->filter to 0 so we don't fallback on the default change
         * notify backend. It's not cluster coherent or cross-protocol so we
         * can't guarantee correctness using it. */
        e->filter = 0;
        e->subdir_filter = 0;

        /* Snapshots do not currently allow event listeners. See Isilon
         * bug 33476 for an example of .snapshot debug spew that can occur. */
        if (e->dir_id.extid != HEAD_SNAPID)
                return NT_STATUS_INVALID_PARAMETER;

        /* Convert Completion Filter mask to IFS Event mask */
        ifs_filter = onefs_notify_smb_filter_to_ifs_filter(smb_filter);

        if (smb_filter & ONEFS_NOTIFY_UNSUPPORTED) {
                /* One or more of the filter bits could not be fully handled by
                 * the ifs_event system. To be correct, if we cannot service a
                 * bit in the completion filter we should return
                 * NT_STATUS_NOT_IMPLEMENTED to let the client know that they
                 * won't be receiving all the notify events that they asked for.
                 * Unfortunately, WinXP clients cache this error message, stop
                 * trying to send any notify requests at all, and instead return
                 * NOT_IMPLEMENTED to all requesting apps without ever sending a
                 * message to us. Thus we lie, and say we can service all bits,
                 * but simply don't return actions for the filter bits we can't
                 * detect or fully implement. */
                DEBUG(3,("One or more of the Windows completion filter bits "
                         "for \"%s\" could not be fully handled by the "
                         "ifs_event system. The failed bits are "
                         "smb_filter=%#x\n",
                         e->path, smb_filter & ONEFS_NOTIFY_UNSUPPORTED));
        }

        if (ifs_filter == 0) {
                /* None of the filter bits given are supported by the ifs_event
                 * system. Don't create a kernel notify channel, but mock
                 * up a fake handle for the caller. */
                DEBUG(3,("No bits in the Windows completion filter could be "
                         "translated to ifs_event mask for \"%s\", "
                         "smb_filter=%#x\n", e->path, smb_filter));
                (*handle) = NULL;
                return NT_STATUS_OK;
        }

        /* Register an ifs event channel for this watch request */
        ifs_event_fd = ifs_create_listener(watch_tree ?
                                           EVENT_RECURSIVE :
                                           EVENT_CHILDREN,
                                           ifs_filter,
                                           e->dir_fd);
        if (ifs_event_fd < 0) {
                DEBUG(0,("Failed to create listener for %s with \"%s\". "
                        "smb_filter=0x%x, ifs_filter=0x%x, watch_tree=%u\n",
                        strerror(errno), e->path, smb_filter, ifs_filter,
                        watch_tree));
                return map_nt_error_from_unix(errno);
        }

        /* Create a watch context to track this change notify request */
        wc = talloc(ctx, struct onefs_notify_watch_context);
        if (wc == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto err;
        }

        /* Get LIN for directory */
        if (onefs_sys_fstat(e->dir_fd, &sbuf)) {
                DEBUG(0, ("stat on directory fd failed: %s\n",
                          strerror(errno)));
                status = map_nt_error_from_unix(errno);
                goto err;
        }

        if (sbuf.st_ex_ino == 0) {
                DEBUG(0, ("0 LIN found!\n"));
                goto err;
        }

        wc->ctx = ctx;
        wc->watch_fd = e->dir_fd;
        wc->watch_lin = sbuf.st_ex_ino;
        wc->ifs_event_fd = ifs_event_fd;
        wc->ifs_filter = ifs_filter;
        wc->smb_filter = smb_filter;
        wc->callback = callback;
        wc->private_data = private_data;
        wc->path = talloc_strdup(wc, e->path);
        if (wc->path == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto err;
        }

        (*handle) = wc;

        /* The caller frees the handle to stop watching */
        talloc_set_destructor(wc, onefs_watch_destructor);

        /* Add a tevent waiting for the ifs event fd to be readable */
        event_add_fd(ctx->ev, wc, wc->ifs_event_fd, EVENT_FD_READ,
                     onefs_notify_handler, wc);

        DEBUG(10, ("Watching for changes on \"%s\" smb_filter=0x%x, "
                   "ifs_filter=0x%x, watch_tree=%d, ifs_event_fd=%d, "
                   "dir_fd=%d, dir_lin=0x%llx\n",
                   e->path, smb_filter, ifs_filter, watch_tree,
                   ifs_event_fd, e->dir_fd, sbuf.st_ex_ino));

        return NT_STATUS_OK;

err:
        talloc_free(wc);
        SMB_ASSERT(ifs_event_fd >= 0);
        close(ifs_event_fd);
        return status;
}