c9e45581ad
This patch allows a failed path group initialisation command to be retried. It adds a generic MP_RETRY flag and a "pg_init_retries" feature to device-mapper multipath which limits the number of retries. 1. A hw handler sends a path initialization command to the storage and the command completes with an error code indicating the command should be retried. 2. The hardware handler calls dm_pg_init_complete() with MP_RETRY set in err_flags to ask the dm multipath core to retry. 3. If the retry limit has not been exceeded, pg_init() is retried. Otherwise fail_path() is called. If you are using the userspace multipath-tools or device-mapper-multipath package, you can set pg_init_retries in the 'device' section of your /etc/multipath.conf file. For example: features "2 pg_init_retries 7" The number of PG retries attempted is reported in the 'dmsetup status' output. Signed-off-by: Dave Wysochanski <dwysocha@redhat.com> Acked-by: Mike Christie <michaelc@cs.wisc.edu> Acked-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/*
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* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
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*
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* This file is released under the GPL.
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*
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* Multipath hardware handler registration.
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*/
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#ifndef DM_HW_HANDLER_H
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#define DM_HW_HANDLER_H
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#include <linux/device-mapper.h>
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#include "dm-mpath.h"
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struct hw_handler_type;
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struct hw_handler {
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struct hw_handler_type *type;
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struct mapped_device *md;
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void *context;
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};
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/*
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* Constructs a hardware handler object, takes custom arguments
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*/
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/* Information about a hardware handler type */
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struct hw_handler_type {
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char *name;
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struct module *module;
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int (*create) (struct hw_handler *handler, unsigned int argc,
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char **argv);
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void (*destroy) (struct hw_handler *hwh);
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void (*pg_init) (struct hw_handler *hwh, unsigned bypassed,
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struct dm_path *path);
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unsigned (*error) (struct hw_handler *hwh, struct bio *bio);
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int (*status) (struct hw_handler *hwh, status_type_t type,
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char *result, unsigned int maxlen);
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};
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/* Register a hardware handler */
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int dm_register_hw_handler(struct hw_handler_type *type);
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/* Unregister a hardware handler */
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int dm_unregister_hw_handler(struct hw_handler_type *type);
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/* Returns a registered hardware handler type */
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struct hw_handler_type *dm_get_hw_handler(const char *name);
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/* Releases a hardware handler */
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void dm_put_hw_handler(struct hw_handler_type *hwht);
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/* Default err function */
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unsigned dm_scsi_err_handler(struct hw_handler *hwh, struct bio *bio);
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/* Error flags for err and dm_pg_init_complete */
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#define MP_FAIL_PATH 1
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#define MP_BYPASS_PG 2
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#define MP_ERROR_IO 4 /* Don't retry this I/O */
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#define MP_RETRY 8
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#endif
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