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-rw-r--r--sys/dev/dm/dm_table.c273
1 files changed, 273 insertions, 0 deletions
diff --git a/sys/dev/dm/dm_table.c b/sys/dev/dm/dm_table.c
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+/* $NetBSD: dm_table.c,v 1.2 2008/12/19 15:24:03 haad Exp $ */
+
+/*
+ * Copyright (c) 2008 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Adam Hamsik.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/param.h>
+
+#include <sys/kmem.h>
+
+#include "dm.h"
+
+/*
+ * There are two types of users of this interface:
+ *
+ * a) Readers such as
+ * dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl,
+ * dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl
+ *
+ * b) Writers such as
+ * dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl
+ *
+ * Writers can work with table_head only when there are no readers. I
+ * use reference counting on io_cnt.
+ *
+ */
+
+static int dm_table_busy(dm_table_head_t *, uint8_t );
+static void dm_table_unbusy(dm_table_head_t *);
+
+/*
+ * Function to increment table user reference counter. Return id
+ * of table_id table.
+ * DM_TABLE_ACTIVE will return active table id.
+ * DM_TABLE_INACTIVE will return inactive table id.
+ */
+static int
+dm_table_busy(dm_table_head_t *head, uint8_t table_id)
+{
+ uint8_t id;
+
+ id = 0;
+
+ mutex_enter(&head->table_mtx);
+
+ if (table_id == DM_TABLE_ACTIVE)
+ id = head->cur_active_table;
+ else
+ id = 1 - head->cur_active_table;
+
+ head->io_cnt++;
+
+ mutex_exit(&head->table_mtx);
+ return id;
+}
+
+/*
+ * Function release table lock and eventually wakeup all waiters.
+ */
+static void
+dm_table_unbusy(dm_table_head_t *head)
+{
+ KASSERT(head->io_cnt != 0);
+
+ mutex_enter(&head->table_mtx);
+
+ if (--head->io_cnt == 0)
+ cv_broadcast(&head->table_cv);
+
+ mutex_exit(&head->table_mtx);
+}
+
+/*
+ * Return current active table to caller, increment io_cnt reference counter.
+ */
+dm_table_t *
+dm_table_get_entry(dm_table_head_t *head, uint8_t table_id)
+{
+ uint8_t id;
+
+ id = dm_table_busy(head, table_id);
+
+ return &head->tables[id];
+}
+
+/*
+ * Decrement io reference counter and wake up all callers, with table_head cv.
+ */
+void
+dm_table_release(dm_table_head_t *head, uint8_t table_id)
+{
+ dm_table_unbusy(head);
+}
+
+/*
+ * Switch table from inactive to active mode. Have to wait until io_cnt is 0.
+ */
+void
+dm_table_switch_tables(dm_table_head_t *head)
+{
+ mutex_enter(&head->table_mtx);
+
+ while (head->io_cnt != 0)
+ cv_wait(&head->table_cv, &head->table_mtx);
+
+ head->cur_active_table = 1 - head->cur_active_table;
+
+ mutex_exit(&head->table_mtx);
+}
+
+/*
+ * Destroy all table data. This function can run when there are no
+ * readers on table lists.
+ *
+ * XXX Is it ok to call kmem_free and potentialy VOP_CLOSE with held mutex ?xs
+ */
+int
+dm_table_destroy(dm_table_head_t *head, uint8_t table_id)
+{
+ dm_table_t *tbl;
+ dm_table_entry_t *table_en;
+ uint8_t id;
+
+ mutex_enter(&head->table_mtx);
+
+ printf("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt);
+
+ while (head->io_cnt != 0)
+ cv_wait(&head->table_cv, &head->table_mtx);
+
+ if (table_id == DM_TABLE_ACTIVE)
+ id = head->cur_active_table;
+ else
+ id = 1 - head->cur_active_table;
+
+ tbl = &head->tables[id];
+
+ while (!SLIST_EMPTY(tbl)) { /* List Deletion. */
+ table_en = SLIST_FIRST(tbl);
+ /*
+ * Remove target specific config data. After successfull
+ * call table_en->target_config must be set to NULL.
+ */
+ table_en->target->destroy(table_en);
+
+ SLIST_REMOVE_HEAD(tbl, next);
+
+ kmem_free(table_en, sizeof(*table_en));
+ }
+
+ mutex_exit(&head->table_mtx);
+
+ return 0;
+}
+
+/*
+ * Return length of active table in device.
+ */
+uint64_t
+dm_table_size(dm_table_head_t *head)
+{
+ dm_table_t *tbl;
+ dm_table_entry_t *table_en;
+ uint64_t length;
+ uint8_t id;
+
+ length = 0;
+
+ id = dm_table_busy(head, DM_TABLE_ACTIVE);
+
+ /* Select active table */
+ tbl = &head->tables[id];
+
+ /*
+ * Find out what tables I want to select.
+ * if length => rawblkno then we should used that table.
+ */
+ SLIST_FOREACH(table_en, tbl, next)
+ length += table_en->length;
+
+ dm_table_unbusy(head);
+
+ return length / DEV_BSIZE;
+}
+
+/*
+ * Return > 0 if table is at least one table entry (returns number of entries)
+ * and return 0 if there is not. Target count returned from this function
+ * doesn't need to be true when userspace user receive it (after return
+ * there can be dm_dev_resume_ioctl), therfore this isonly informative.
+ */
+int
+dm_table_get_target_count(dm_table_head_t *head, uint8_t table_id)
+{
+ dm_table_entry_t *table_en;
+ dm_table_t *tbl;
+ uint32_t target_count;
+ uint8_t id;
+
+ target_count = 0;
+
+ id = dm_table_busy(head, table_id);
+
+ tbl = &head->tables[id];
+
+ SLIST_FOREACH(table_en, tbl, next)
+ target_count++;
+
+ dm_table_unbusy(head);
+
+ return target_count;
+}
+
+
+/*
+ * Initialize table_head structures, I'm trying to keep this structure as
+ * opaque as possible.
+ */
+void
+dm_table_head_init(dm_table_head_t *head)
+{
+ head->cur_active_table = 0;
+ head->io_cnt = 0;
+
+ /* Initialize tables. */
+ SLIST_INIT(&head->tables[0]);
+ SLIST_INIT(&head->tables[1]);
+
+ mutex_init(&head->table_mtx, MUTEX_DEFAULT, IPL_NONE);
+ cv_init(&head->table_cv, "dm_io");
+}
+
+/*
+ * Destroy all variables in table_head
+ */
+void
+dm_table_head_destroy(dm_table_head_t *head)
+{
+ KASSERT(!mutex_owned(&head->table_mtx));
+ KASSERT(!cv_has_waiters(&head->table_cv));
+ /* tables doens't exists when I call this routine, therefore
+ it doesn't make sense to have io_cnt != 0 */
+ KASSERT(head->io_cnt == 0);
+
+ cv_destroy(&head->table_cv);
+ mutex_destroy(&head->table_mtx);
+}