10d3bd09a3
Change dm_unregister_target to return void and use BUG() for error reporting. dm_unregister_target can only fail because of programming bug in the target driver. It can't fail because of user's behavior or disk errors. This patch changes unregister_target to return void and use BUG if someone tries to unregister non-registered target or unregister target that is in use. This patch removes code duplication (testing of error codes in all dm targets) and reports bugs in just one place, in dm_unregister_target. In some target drivers, these return codes were ignored, which could lead to a situation where bugs could be missed. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
80 lines
1.5 KiB
C
80 lines
1.5 KiB
C
/*
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* Copyright (C) 2003 Christophe Saout <christophe@saout.de>
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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/device-mapper.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/bio.h>
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#define DM_MSG_PREFIX "zero"
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/*
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* Construct a dummy mapping that only returns zeros
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*/
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static int zero_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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{
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if (argc != 0) {
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ti->error = "No arguments required";
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return -EINVAL;
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}
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return 0;
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}
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/*
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* Return zeros only on reads
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*/
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static int zero_map(struct dm_target *ti, struct bio *bio,
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union map_info *map_context)
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{
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switch(bio_rw(bio)) {
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case READ:
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zero_fill_bio(bio);
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break;
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case READA:
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/* readahead of null bytes only wastes buffer cache */
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return -EIO;
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case WRITE:
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/* writes get silently dropped */
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break;
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}
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bio_endio(bio, 0);
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/* accepted bio, don't make new request */
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return DM_MAPIO_SUBMITTED;
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}
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static struct target_type zero_target = {
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.name = "zero",
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.version = {1, 0, 0},
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.module = THIS_MODULE,
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.ctr = zero_ctr,
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.map = zero_map,
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};
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static int __init dm_zero_init(void)
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{
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int r = dm_register_target(&zero_target);
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if (r < 0)
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DMERR("register failed %d", r);
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return r;
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}
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static void __exit dm_zero_exit(void)
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{
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dm_unregister_target(&zero_target);
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}
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module_init(dm_zero_init)
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module_exit(dm_zero_exit)
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MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
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MODULE_DESCRIPTION(DM_NAME " dummy target returning zeros");
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MODULE_LICENSE("GPL");
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