1 files changed, 216 insertions, 0 deletions

diff --git a/drivers/md/dm-hw-handler.c b/drivers/md/dm-hw-handler.c
new file mode 100644
index 000000000000..ae63772e44c9
--- /dev/null
+++ b/drivers/md/dm-hw-handler.c
@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ *
+ * Multipath hardware handler registration.
+ */
+
+#include "dm.h"
+#include "dm-hw-handler.h"
+
+#include <linux/slab.h>
+
+struct hwh_internal {
+        struct hw_handler_type hwht;
+
+        struct list_head list;
+        long use;
+};
+
+#define hwht_to_hwhi(__hwht) container_of((__hwht), struct hwh_internal, hwht)
+
+static LIST_HEAD(_hw_handlers);
+static DECLARE_RWSEM(_hwh_lock);
+
+struct hwh_internal *__find_hw_handler_type(const char *name)
+{
+        struct hwh_internal *hwhi;
+
+        list_for_each_entry(hwhi, &_hw_handlers, list) {
+                if (!strcmp(name, hwhi->hwht.name))
+                        return hwhi;
+        }
+
+        return NULL;
+}
+
+static struct hwh_internal *get_hw_handler(const char *name)
+{
+        struct hwh_internal *hwhi;
+
+        down_read(&_hwh_lock);
+        hwhi = __find_hw_handler_type(name);
+        if (hwhi) {
+                if ((hwhi->use == 0) && !try_module_get(hwhi->hwht.module))
+                        hwhi = NULL;
+                else
+                        hwhi->use++;
+        }
+        up_read(&_hwh_lock);
+
+        return hwhi;
+}
+
+struct hw_handler_type *dm_get_hw_handler(const char *name)
+{
+        struct hwh_internal *hwhi;
+
+        if (!name)
+                return NULL;
+
+        hwhi = get_hw_handler(name);
+        if (!hwhi) {
+                request_module("dm-%s", name);
+                hwhi = get_hw_handler(name);
+        }
+
+        return hwhi ? &hwhi->hwht : NULL;
+}
+
+void dm_put_hw_handler(struct hw_handler_type *hwht)
+{
+        struct hwh_internal *hwhi;
+
+        if (!hwht)
+                return;
+
+        down_read(&_hwh_lock);
+        hwhi = __find_hw_handler_type(hwht->name);
+        if (!hwhi)
+                goto out;
+
+        if (--hwhi->use == 0)
+                module_put(hwhi->hwht.module);
+
+        if (hwhi->use < 0)
+                BUG();
+
+      out:
+        up_read(&_hwh_lock);
+}
+
+static struct hwh_internal *_alloc_hw_handler(struct hw_handler_type *hwht)
+{
+        struct hwh_internal *hwhi = kmalloc(sizeof(*hwhi), GFP_KERNEL);
+
+        if (hwhi) {
+                memset(hwhi, 0, sizeof(*hwhi));
+                hwhi->hwht = *hwht;
+        }
+
+        return hwhi;
+}
+
+int dm_register_hw_handler(struct hw_handler_type *hwht)
+{
+        int r = 0;
+        struct hwh_internal *hwhi = _alloc_hw_handler(hwht);
+
+        if (!hwhi)
+                return -ENOMEM;
+
+        down_write(&_hwh_lock);
+
+        if (__find_hw_handler_type(hwht->name)) {
+                kfree(hwhi);
+                r = -EEXIST;
+        } else
+                list_add(&hwhi->list, &_hw_handlers);
+
+        up_write(&_hwh_lock);
+
+        return r;
+}
+
+int dm_unregister_hw_handler(struct hw_handler_type *hwht)
+{
+        struct hwh_internal *hwhi;
+
+        down_write(&_hwh_lock);
+
+        hwhi = __find_hw_handler_type(hwht->name);
+        if (!hwhi) {
+                up_write(&_hwh_lock);
+                return -EINVAL;
+        }
+
+        if (hwhi->use) {
+                up_write(&_hwh_lock);
+                return -ETXTBSY;
+        }
+
+        list_del(&hwhi->list);
+
+        up_write(&_hwh_lock);
+
+        kfree(hwhi);
+
+        return 0;
+}
+
+unsigned dm_scsi_err_handler(struct hw_handler *hwh, struct bio *bio)
+{
+#if 0
+        int sense_key, asc, ascq;
+
+        if (bio->bi_error & BIO_SENSE) {
+                /* FIXME: This is just an initial guess. */
+                /* key / asc / ascq */
+                sense_key = (bio->bi_error >> 16) & 0xff;
+                asc = (bio->bi_error >> 8) & 0xff;
+                ascq = bio->bi_error & 0xff;
+
+                switch (sense_key) {
+                        /* This block as a whole comes from the device.
+                         * So no point retrying on another path. */
+                case 0x03:      /* Medium error */
+                case 0x05:      /* Illegal request */
+                case 0x07:      /* Data protect */
+                case 0x08:      /* Blank check */
+                case 0x0a:      /* copy aborted */
+                case 0x0c:      /* obsolete - no clue ;-) */
+                case 0x0d:      /* volume overflow */
+                case 0x0e:      /* data miscompare */
+                case 0x0f:      /* reserved - no idea either. */
+                        return MP_ERROR_IO;
+
+                        /* For these errors it's unclear whether they
+                         * come from the device or the controller.
+                         * So just lets try a different path, and if
+                         * it eventually succeeds, user-space will clear
+                         * the paths again... */
+                case 0x02:      /* Not ready */
+                case 0x04:      /* Hardware error */
+                case 0x09:      /* vendor specific */
+                case 0x0b:      /* Aborted command */
+                        return MP_FAIL_PATH;
+
+                case 0x06:      /* Unit attention - might want to decode */
+                        if (asc == 0x04 && ascq == 0x01)
+                                /* "Unit in the process of
+                                 * becoming ready" */
+                                return 0;
+                        return MP_FAIL_PATH;
+
+                        /* FIXME: For Unit Not Ready we may want
+                         * to have a generic pg activation
+                         * feature (START_UNIT). */
+
+                        /* Should these two ever end up in the
+                         * error path? I don't think so. */
+                case 0x00:      /* No sense */
+                case 0x01:      /* Recovered error */
+                        return 0;
+                }
+        }
+#endif
+
+        /* We got no idea how to decode the other kinds of errors ->
+         * assume generic error condition. */
+        return MP_FAIL_PATH;
+}
+
+EXPORT_SYMBOL_GPL(dm_register_hw_handler);
+EXPORT_SYMBOL_GPL(dm_unregister_hw_handler);
+EXPORT_SYMBOL_GPL(dm_scsi_err_handler);