s3:smbd: add a scavenger process for disconnected durable handles

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Gregor Beck <gbeck@sernet.de>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>

1 files changed, 531 insertions, 0 deletions

diff --git a/source3/smbd/scavenger.c b/source3/smbd/scavenger.c
new file mode 100644
index 0000000000..fe4e56e613
--- /dev/null
+++ b/source3/smbd/scavenger.c
@@ -0,0 +1,531 @@
+/*
+   Unix SMB/CIFS implementation.
+   smbd scavenger daemon
+
+   Copyright (C) Gregor Beck                    2013
+
+   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/>.
+*/
+
+#include "includes.h"
+
+#include "messages.h"
+#include "serverid.h"
+#include "smbd/globals.h"
+#include "smbd/scavenger.h"
+#include "locking/proto.h"
+#include "lib/util/util_process.h"
+
+#undef DBGC_CLASS
+#define DBGC_CLASS DBGC_SCAVENGER
+
+struct smbd_scavenger_state {
+	struct tevent_context *ev;
+	struct messaging_context *msg;
+	struct server_id parent_id;
+	struct server_id *scavenger_id;
+	bool am_scavenger;
+};
+
+static struct smbd_scavenger_state *smbd_scavenger_state = NULL;
+
+struct scavenger_message {
+	struct file_id file_id;
+	uint64_t open_persistent_id;
+	NTTIME until;
+};
+
+static int smbd_scavenger_main(struct smbd_scavenger_state *state)
+{
+	DEBUG(10, ("scavenger: %s started, parent: %s\n",
+		   server_id_str(talloc_tos(), state->scavenger_id),
+		   server_id_str(talloc_tos(), &state->parent_id)));
+
+	while (true) {
+		TALLOC_CTX *frame = talloc_stackframe();
+		int ret;
+
+		ret = tevent_loop_once(state->ev);
+		if (ret != 0) {
+			DEBUG(2, ("tevent_loop_once failed: %s\n",
+				  strerror(errno)));
+			TALLOC_FREE(frame);
+			return 1;
+		}
+
+		DEBUG(10, ("scavenger: %s event loop iteration\n",
+			   server_id_str(talloc_tos(), state->scavenger_id)));
+		TALLOC_FREE(frame);
+	}
+
+	return 0;
+}
+
+static void smbd_scavenger_done(struct tevent_context *event_ctx, struct tevent_fd *fde,
+			        uint16_t flags, void *private_data)
+{
+	struct smbd_scavenger_state *state = talloc_get_type_abort(
+		private_data, struct smbd_scavenger_state);
+
+	DEBUG(2, ("scavenger: %s died\n",
+		  server_id_str(talloc_tos(), state->scavenger_id)));
+
+	TALLOC_FREE(state->scavenger_id);
+}
+
+static void smbd_scavenger_parent_dead(struct tevent_context *event_ctx,
+				       struct tevent_fd *fde,
+				       uint16_t flags, void *private_data)
+{
+	struct smbd_scavenger_state *state = talloc_get_type_abort(
+		private_data, struct smbd_scavenger_state);
+
+	DEBUG(2, ("scavenger: %s parent %s died\n",
+		  server_id_str(talloc_tos(), state->scavenger_id),
+		  server_id_str(talloc_tos(), &state->parent_id)));
+
+	exit_server("smbd_scavenger_parent_dead");
+}
+
+static void scavenger_sig_term_handler(struct tevent_context *ev,
+				       struct tevent_signal *se,
+				       int signum,
+				       int count,
+				       void *siginfo,
+				       void *private_data)
+{
+	exit_server_cleanly("termination signal");
+}
+
+static void scavenger_setup_sig_term_handler(struct tevent_context *ev_ctx)
+{
+	struct tevent_signal *se;
+
+	se = tevent_add_signal(ev_ctx,
+			       ev_ctx,
+			       SIGTERM, 0,
+			       scavenger_sig_term_handler,
+			       NULL);
+	if (se == NULL) {
+		exit_server("failed to setup SIGTERM handler");
+	}
+}
+
+static bool smbd_scavenger_running(struct smbd_scavenger_state *state)
+{
+	if (state->scavenger_id == NULL) {
+		return false;
+	}
+
+	return serverid_exists(state->scavenger_id);
+}
+
+static int smbd_scavenger_server_id_destructor(struct server_id *id)
+{
+	serverid_deregister(*id);
+	return 0;
+}
+
+static bool scavenger_say_hello(int fd, struct server_id self)
+{
+	const uint8_t *msg = (const uint8_t *)&self;
+	size_t remaining = sizeof(self);
+	size_t ofs = 0;
+
+	while (remaining > 0) {
+		ssize_t ret;
+
+		ret = sys_write(fd, msg + ofs, remaining);
+		if (ret == -1) {
+			DEBUG(2, ("Failed to write to pipe: %s\n",
+				  strerror(errno)));
+			return false;
+		}
+		remaining -= ret;
+	}
+
+	DEBUG(4, ("scavenger_say_hello: self[%s]\n",
+		  server_id_str(talloc_tos(), &self)));
+	return true;
+}
+
+static bool scavenger_wait_hello(int fd, struct server_id *child)
+{
+	uint8_t *msg = (uint8_t *)child;
+	size_t remaining = sizeof(*child);
+	size_t ofs = 0;
+
+	while (remaining > 0) {
+		ssize_t ret;
+
+		ret = sys_read(fd, msg + ofs, remaining);
+		if (ret == -1) {
+			DEBUG(2, ("Failed to read from pipe: %s\n",
+				  strerror(errno)));
+			return false;
+		}
+		remaining -= ret;
+	}
+
+	DEBUG(4, ("scavenger_say_hello: child[%s]\n",
+		  server_id_str(talloc_tos(), child)));
+	return true;
+}
+
+static bool smbd_scavenger_start(struct smbd_scavenger_state *state)
+{
+	struct server_id self = messaging_server_id(state->msg);
+	struct tevent_fd *fde = NULL;
+	int fds[2];
+	int ret;
+	uint64_t unique_id;
+	bool ok;
+
+	SMB_ASSERT(server_id_equal(&state->parent_id, &self));
+
+	if (smbd_scavenger_running(state)) {
+		DEBUG(10, ("scavenger %s already running\n",
+			   server_id_str(talloc_tos(),
+					 state->scavenger_id)));
+		return true;
+	}
+
+	if (state->scavenger_id != NULL) {
+		DEBUG(10, ("scavenger zombie %s, cleaning up\n",
+			   server_id_str(talloc_tos(),
+					 state->scavenger_id)));
+		TALLOC_FREE(state->scavenger_id);
+	}
+
+	state->scavenger_id = talloc_zero(state, struct server_id);
+	if (state->scavenger_id == NULL) {
+		DEBUG(2, ("Out of memory\n"));
+		goto fail;
+	}
+	talloc_set_destructor(state->scavenger_id,
+			      smbd_scavenger_server_id_destructor);
+
+	ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
+	if (ret == -1) {
+		DEBUG(2, ("socketpair failed: %s", strerror(errno)));
+		goto fail;
+	}
+
+	smb_set_close_on_exec(fds[0]);
+	smb_set_close_on_exec(fds[1]);
+
+	unique_id = serverid_get_random_unique_id();
+
+	ret = fork();
+	if (ret == -1) {
+		int err = errno;
+		close(fds[0]);
+		close(fds[1]);
+		DEBUG(0, ("fork failed: %s", strerror(err)));
+		goto fail;
+	}
+
+	if (ret == 0) {
+		/* child */
+
+		NTSTATUS status;
+
+		close(fds[0]);
+
+		am_parent = NULL;
+
+		set_my_unique_id(unique_id);
+
+		status = reinit_after_fork(state->msg, state->ev, true);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(2, ("reinit_after_fork failed: %s\n",
+				  nt_errstr(status)));
+			exit_server("reinit_after_fork failed");
+			return false;
+		}
+
+		prctl_set_comment("smbd-scavenger");
+
+		state->am_scavenger = true;
+		*state->scavenger_id = messaging_server_id(state->msg);
+
+		scavenger_setup_sig_term_handler(state->ev);
+
+		serverid_register(*state->scavenger_id, FLAG_MSG_GENERAL);
+
+		ok = scavenger_say_hello(fds[1], *state->scavenger_id);
+		if (!ok) {
+			DEBUG(2, ("scavenger_say_hello failed\n"));
+			exit_server("scavenger_say_hello failed");
+			return false;
+		}
+
+		fde = tevent_add_fd(state->ev, state->scavenger_id,
+				    fds[1], TEVENT_FD_READ,
+				    smbd_scavenger_parent_dead, state);
+		if (fde == NULL) {
+			DEBUG(2, ("tevent_add_fd(smbd_scavenger_parent_dead) "
+				  "failed\n"));
+			exit_server("tevent_add_fd(smbd_scavenger_parent_dead) "
+				    "failed");
+			return false;
+		}
+		tevent_fd_set_auto_close(fde);
+
+		ret = smbd_scavenger_main(state);
+
+		DEBUG(10, ("scavenger ended: %d\n", ret));
+		exit_server_cleanly("scavenger ended");
+		return false;
+	}
+
+	/* parent */
+	close(fds[1]);
+
+	ok = scavenger_wait_hello(fds[0], state->scavenger_id);
+	if (!ok) {
+		close(fds[0]);
+		goto fail;
+	}
+
+	fde = tevent_add_fd(state->ev, state->scavenger_id,
+			    fds[0], TEVENT_FD_READ,
+			    smbd_scavenger_done, state);
+	if (fde == NULL) {
+		close(fds[0]);
+		goto fail;
+	}
+	tevent_fd_set_auto_close(fde);
+
+	return true;
+fail:
+	TALLOC_FREE(state->scavenger_id);
+	return false;
+}
+
+static void scavenger_add_timer(struct smbd_scavenger_state *state,
+				struct scavenger_message *msg);
+
+static void smbd_scavenger_msg(struct messaging_context *msg_ctx,
+			       void *private_data,
+			       uint32_t msg_type,
+			       struct server_id src,
+			       DATA_BLOB *data)
+{
+	struct smbd_scavenger_state *state =
+		talloc_get_type_abort(private_data,
+				      struct smbd_scavenger_state);
+	TALLOC_CTX *frame = talloc_stackframe();
+	struct server_id self = messaging_server_id(msg_ctx);
+	struct scavenger_message *msg = NULL;
+
+	DEBUG(10, ("smbd_scavenger_msg: %s got message from %s\n",
+		   server_id_str(talloc_tos(), &self),
+		   server_id_str(talloc_tos(), &src)));
+
+	if (server_id_equal(&state->parent_id, &self)) {
+		NTSTATUS status;
+
+		if (!smbd_scavenger_running(state) &&
+		    !smbd_scavenger_start(state))
+		{
+			DEBUG(2, ("Failed to start scavenger\n"));
+			goto done;
+		}
+		DEBUG(10, ("forwarding message to scavenger\n"));
+
+		status = messaging_send(msg_ctx,
+					*state->scavenger_id, msg_type, data);
+		if (!NT_STATUS_IS_OK(status)) {
+			DEBUG(2, ("forwarding message to scavenger failed: "
+				  "%s\n", nt_errstr(status)));
+			goto done;
+		}
+		goto done;
+	}
+
+	if (!state->am_scavenger) {
+		DEBUG(10, ("im not the scavenger: ignore message\n"));
+		goto done;
+	}
+
+	if (!server_id_equal(&state->parent_id, &src)) {
+		DEBUG(10, ("scavenger: ignore spurious message\n"));
+		goto done;
+	}
+
+	DEBUG(10, ("scavenger: got a message\n"));
+	msg = (struct scavenger_message*)data->data;
+	scavenger_add_timer(state, msg);
+done:
+	talloc_free(frame);
+}
+
+bool smbd_scavenger_init(TALLOC_CTX *mem_ctx,
+			 struct messaging_context *msg,
+			 struct tevent_context *ev)
+{
+	struct smbd_scavenger_state *state;
+	NTSTATUS status;
+
+	if (smbd_scavenger_state) {
+		DEBUG(10, ("smbd_scavenger_init called again\n"));
+		return true;
+	}
+
+	state = talloc_zero(mem_ctx, struct smbd_scavenger_state);
+	if (state == NULL) {
+		DEBUG(2, ("Out of memory\n"));
+		return false;
+	}
+
+	state->msg = msg;
+	state->ev = ev;
+	state->parent_id = messaging_server_id(msg);
+
+	status = messaging_register(msg, state, MSG_SMB_SCAVENGER,
+				    smbd_scavenger_msg);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(2, ("failed to register message handler: %s\n",
+			  nt_errstr(status)));
+		goto fail;
+	}
+
+	smbd_scavenger_state = state;
+	return true;
+fail:
+	talloc_free(state);
+	return false;
+}
+
+void scavenger_schedule_disconnected(struct files_struct *fsp)
+{
+	NTSTATUS status;
+	struct server_id self = messaging_server_id(fsp->conn->sconn->msg_ctx);
+	struct timeval disconnect_time, until;
+	uint64_t timeout_usec;
+	struct scavenger_message msg;
+	DATA_BLOB msg_blob;
+
+	nttime_to_timeval(&disconnect_time, fsp->op->global->disconnect_time);
+	timeout_usec = 1000 * fsp->op->global->durable_timeout_msec;
+	until = timeval_add(&disconnect_time,
+			    timeout_usec / 1000000,
+			    timeout_usec % 1000000);
+
+	ZERO_STRUCT(msg);
+	msg.file_id = fsp->file_id;
+	msg.open_persistent_id = fsp->op->global->open_persistent_id;
+	msg.until = timeval_to_nttime(&until);
+
+	DEBUG(10, ("smbd: %s mark file %s as disconnected at %s with timeout "
+		   "at %s in %fs\n",
+		   server_id_str(talloc_tos(), &self),
+		   file_id_string_tos(&fsp->file_id),
+		   timeval_string(talloc_tos(), &disconnect_time, true),
+		   timeval_string(talloc_tos(), &until, true),
+		   fsp->op->global->durable_timeout_msec/1000.0));
+
+	SMB_ASSERT(server_id_is_disconnected(&fsp->op->global->server_id));
+	SMB_ASSERT(!server_id_equal(&self, &smbd_scavenger_state->parent_id));
+	SMB_ASSERT(!smbd_scavenger_state->am_scavenger);
+
+	msg_blob = data_blob_const(&msg, sizeof(msg));
+	DEBUG(10, ("send message to scavenger\n"));
+
+	status = messaging_send(smbd_scavenger_state->msg,
+				smbd_scavenger_state->parent_id,
+				MSG_SMB_SCAVENGER,
+				&msg_blob);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(2, ("Failed to send message to parent smbd %s "
+			  "from %s: %s\n",
+			  server_id_str(talloc_tos(),
+					&smbd_scavenger_state->parent_id),
+			  server_id_str(talloc_tos(), &self),
+			  nt_errstr(status)));
+	}
+}
+
+struct scavenger_timer_context {
+	struct smbd_scavenger_state *state;
+	struct scavenger_message msg;
+};
+
+static void scavenger_timer(struct tevent_context *ev,
+			    struct tevent_timer *te,
+			    struct timeval t, void *data)
+{
+	struct scavenger_timer_context *ctx =
+		talloc_get_type_abort(data, struct scavenger_timer_context);
+	NTSTATUS status;
+	bool ok;
+
+	DEBUG(10, ("scavenger: do cleanup for file %s at %s\n",
+		  file_id_string_tos(&ctx->msg.file_id),
+		  timeval_string(talloc_tos(), &t, true)));
+
+	ok = share_mode_cleanup_disconnected(ctx->msg.file_id,
+					     ctx->msg.open_persistent_id);
+	if (!ok) {
+		DEBUG(2, ("Failed to cleanup share modes and byte range locks "
+			  "for file %s open %lu\n",
+			  file_id_string_tos(&ctx->msg.file_id),
+			  ctx->msg.open_persistent_id));
+	}
+
+	status = smbXsrv_open_cleanup(ctx->msg.open_persistent_id);
+	if (!NT_STATUS_IS_OK(status)) {
+		DEBUG(2, ("Failed to cleanup open global for file %s open %lu:"
+			  " %s\n", file_id_string_tos(&ctx->msg.file_id),
+			  ctx->msg.open_persistent_id, nt_errstr(status)));
+	}
+}
+
+static void scavenger_add_timer(struct smbd_scavenger_state *state,
+				struct scavenger_message *msg)
+{
+	struct tevent_timer *te;
+	struct scavenger_timer_context *ctx;
+	struct timeval until;
+
+	nttime_to_timeval(&until, msg->until);
+
+	DEBUG(10, ("scavenger: schedule file %s for cleanup at %s\n",
+		   file_id_string_tos(&msg->file_id),
+		   timeval_string(talloc_tos(), &until, true)));
+
+	ctx = talloc_zero(state, struct scavenger_timer_context);
+	if (ctx == NULL) {
+		DEBUG(2, ("Failed to talloc_zero(scavenger_timer_context)\n"));
+		return;
+	}
+
+	ctx->state = state;
+	ctx->msg = *msg;
+
+	te = tevent_add_timer(state->ev,
+			      state,
+			      until,
+			      scavenger_timer,
+			      ctx);
+	if (te == NULL) {
+		DEBUG(2, ("Failed to add scavenger_timer event\n"));
+		talloc_free(ctx);
+		return;
+	}
+
+	/* delete context after handler was running */
+	talloc_steal(te, ctx);
+}