55a62eef8d
Use 'bio' in the name of variables and functions that deal with bios rather than 'request' to avoid confusion with the normal block layer use of 'request'. No functional changes. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
154 lines
2.6 KiB
C
154 lines
2.6 KiB
C
/*
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* Copyright (C) 2001 Sistina Software (UK) Limited
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*
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* This file is released under the GPL.
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*/
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#include "dm.h"
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kmod.h>
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#include <linux/bio.h>
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#define DM_MSG_PREFIX "target"
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static LIST_HEAD(_targets);
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static DECLARE_RWSEM(_lock);
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#define DM_MOD_NAME_SIZE 32
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static inline struct target_type *__find_target_type(const char *name)
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{
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struct target_type *tt;
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list_for_each_entry(tt, &_targets, list)
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if (!strcmp(name, tt->name))
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return tt;
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return NULL;
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}
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static struct target_type *get_target_type(const char *name)
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{
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struct target_type *tt;
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down_read(&_lock);
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tt = __find_target_type(name);
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if (tt && !try_module_get(tt->module))
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tt = NULL;
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up_read(&_lock);
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return tt;
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}
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static void load_module(const char *name)
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{
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request_module("dm-%s", name);
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}
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struct target_type *dm_get_target_type(const char *name)
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{
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struct target_type *tt = get_target_type(name);
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if (!tt) {
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load_module(name);
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tt = get_target_type(name);
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}
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return tt;
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}
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void dm_put_target_type(struct target_type *tt)
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{
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down_read(&_lock);
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module_put(tt->module);
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up_read(&_lock);
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}
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int dm_target_iterate(void (*iter_func)(struct target_type *tt,
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void *param), void *param)
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{
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struct target_type *tt;
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down_read(&_lock);
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list_for_each_entry(tt, &_targets, list)
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iter_func(tt, param);
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up_read(&_lock);
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return 0;
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}
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int dm_register_target(struct target_type *tt)
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{
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int rv = 0;
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down_write(&_lock);
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if (__find_target_type(tt->name))
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rv = -EEXIST;
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else
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list_add(&tt->list, &_targets);
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up_write(&_lock);
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return rv;
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}
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void dm_unregister_target(struct target_type *tt)
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{
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down_write(&_lock);
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if (!__find_target_type(tt->name)) {
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DMCRIT("Unregistering unrecognised target: %s", tt->name);
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BUG();
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}
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list_del(&tt->list);
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up_write(&_lock);
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}
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/*
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* io-err: always fails an io, useful for bringing
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* up LVs that have holes in them.
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*/
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static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args)
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{
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/*
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* Return error for discards instead of -EOPNOTSUPP
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*/
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tt->num_discard_bios = 1;
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return 0;
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}
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static void io_err_dtr(struct dm_target *tt)
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{
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/* empty */
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}
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static int io_err_map(struct dm_target *tt, struct bio *bio)
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{
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return -EIO;
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}
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static struct target_type error_target = {
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.name = "error",
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.version = {1, 1, 0},
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.ctr = io_err_ctr,
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.dtr = io_err_dtr,
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.map = io_err_map,
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};
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int __init dm_target_init(void)
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{
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return dm_register_target(&error_target);
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}
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void dm_target_exit(void)
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{
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dm_unregister_target(&error_target);
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}
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EXPORT_SYMBOL(dm_register_target);
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EXPORT_SYMBOL(dm_unregister_target);
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