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126 lines
2.4 KiB
C
126 lines
2.4 KiB
C
/*
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* dm-linear.c
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*
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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 <linux/config.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/device-mapper.h>
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#include "dm.h"
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/*
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* linear: maps a linear range of a device.
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*/
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struct linear_c {
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long delta; /* FIXME: we need a signed offset type */
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struct dm_dev *dev;
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};
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/*
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* construct a linear mapping.
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* <dev_path> <offset>
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*/
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static int linear_ctr(struct dm_table *t, offset_t b, offset_t l,
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struct text_region *args, void **context,
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dm_error_fn err, void *e_private)
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{
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struct linear_c *lc;
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unsigned int start;
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struct text_region word;
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char path[256]; /* FIXME: magic */
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int r = -EINVAL;
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if (!(lc = kmalloc(sizeof(lc), GFP_KERNEL))) {
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err("couldn't allocate memory for linear context", e_private);
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return -ENOMEM;
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}
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if (!dm_get_word(args, &word)) {
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err("couldn't get device path", e_private);
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goto bad;
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}
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dm_txt_copy(path, sizeof(path) - 1, &word);
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if (!dm_get_number(args, &start)) {
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err("destination start not given", e_private);
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goto bad;
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}
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if ((r = dm_table_get_device(t, path, &lc->dev))) {
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err("couldn't lookup device", e_private);
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r = -ENXIO;
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goto bad;
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}
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lc->delta = (int) start - (int) b;
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*context = lc;
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return 0;
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bad:
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kfree(lc);
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return r;
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}
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static void linear_dtr(struct dm_table *t, void *c)
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{
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struct linear_c *lc = (struct linear_c *) c;
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dm_table_put_device(t, lc->dev);
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kfree(c);
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}
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static int linear_map(struct buffer_head *bh, int rw, void *context)
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{
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struct linear_c *lc = (struct linear_c *) context;
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bh->b_rdev = lc->dev->dev;
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bh->b_rsector = bh->b_rsector + lc->delta;
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return 1;
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}
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static struct target_type linear_target = {
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name: "linear",
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module: THIS_MODULE,
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ctr: linear_ctr,
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dtr: linear_dtr,
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map: linear_map,
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};
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static int __init linear_init(void)
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{
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int r = dm_register_target(&linear_target);
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if (r < 0)
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printk(KERN_ERR
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"Device mapper: Linear: register failed %d\n", r);
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return r;
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}
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static void __exit linear_exit(void)
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{
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int r = dm_unregister_target(&linear_target);
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if (r < 0)
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printk(KERN_ERR
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"Device mapper: Linear: unregister failed %d\n", r);
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}
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module_init(linear_init);
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module_exit(linear_exit);
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MODULE_AUTHOR("Joe Thornber <thornber@uk.sistina.com>");
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MODULE_DESCRIPTION("Device Mapper: Linear mapping");
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#ifdef MODULE_LICENSE
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MODULE_LICENSE("GPL");
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#endif
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