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path: root/drivers/md/dm-hw-handler.c
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Diffstat (limited to 'drivers/md/dm-hw-handler.c')
-rw-r--r--drivers/md/dm-hw-handler.c216
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);