sys/dev/disk/dm: Refactor dmioctl()

More readable without dm_ioctl_switch() as a separate function.
taken-from: NetBSD

dm - synchronize disk info before returning

* DM now issues a disk_config(NULL) after setting up the disk info
in order to wait for the probe to complete, otherwise callers
may race trying to op

dm - synchronize disk info before returning

* DM now issues a disk_config(NULL) after setting up the disk info
in order to wait for the probe to complete, otherwise callers
may race trying to open() the disk device before it is actually
ready.

* Fixes cryptsetup luksOpen errors which occur due to probe races,
typically when used in a VM or qemu.

Reported-by: Aaron LI

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sys/dev/disk/dm: Cleanups

This part is unclear for no reason.

sys/dev/disk/dm: Make dmdebug() print __func__

and fix/remove dmdebug calls that could be cleaned up or simplified.

sys/dev/disk/dm: Remove default:break for switch enums on kldload

This could be reverted as compilers may warn if not all enum elements
are covered, but some dm targets don't have default case on lo

sys/dev/disk/dm: Remove default:break for switch enums on kldload

This could be reverted as compilers may warn if not all enum elements
are covered, but some dm targets don't have default case on loading,
and it's been working. Compiles with LINT64.

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sys/dev/disk/dm: Remove #if0'd dmminphys() from NetBSD

This is specific to NetBSD, so we can remove this.

sys/dev/disk/dm: Cleanup

sys/dev/disk/dm: Remove read/write support for /dev/mapper/control

It's obvious that /dev/mapper/control has nothing to read/write.
Running below results in kernel panic as the code requires properl

sys/dev/disk/dm: Remove read/write support for /dev/mapper/control

It's obvious that /dev/mapper/control has nothing to read/write.
Running below results in kernel panic as the code requires properly
initialized a per-table lock while this chrdev has no tables mapped.
(control chrdev and dm blkdevs use the same dm device structures)

-----
[root@]~# cat ./dm1.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
int main(void)
{
int fd;
char buf[1024];
fd = open("/dev/mapper/control", O_RDWR);
if (fd == -1) {
perror("open");
exit(1);
}
if (read(fd, buf, sizeof(buf)) == -1)
perror("read");
if (write(fd, buf, sizeof(buf)) == -1)
perror("write");
close(fd);
return 0;
}

With this commit.
-----
[root@]~# uname
DragonFly
[root@]~# kldload dm
[root@]~# ls -l /dev/mapper/control
crw-r----- 1 root operator 65, 0x00000000 May 1 09:25 /dev/mapper/control
[root@]~# gcc -Wall -g ./dm1.c -o ./dm1
[root@]~# ./dm1
read: Operation not supported by device
write: Operation not supported by device

With Linux kernel.
-----
[root@localhost]~# uname
Linux
[root@localhost]~# ls -l /dev/mapper/control
crw-rw---- 1 root root 10, 236 Apr 25 12:44 /dev/mapper/control
[root@localhost]~# gcc -Wall -g ./dm1.c -o ./dm1
[root@localhost]~# ./dm1
read: Invalid argument
write: Invalid argument

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sys/dev/disk/dm: Cleanup header includes

sys/dev/disk/dm: Cleanups

* Fix comments.
* Add a blank line between functions.
* Some minor fixes on dm core.

sys/dev/disk/dm: Add a comment on race on unload

There is a minor race window in dm_modcmd() after the below
conditional on unloading dm.ko. It's possible to create a new
device after it gets beyond

sys/dev/disk/dm: Add a comment on race on unload

There is a minor race window in dm_modcmd() after the below
conditional on unloading dm.ko. It's possible to create a new
device after it gets beyond the conditional with 0.

if (dm_dev_counter > 0)
return EBUSY;

Running the below a.sh and then b.sh concurrently causes
kernel panic. Avoiding this race seems to be difficult using
the existing locks that are all file local ones. The panic
can be reproduced with or without the previous commit.

===== a.sh
#!/usr/local/bin/bash
while [ 1 ]; do
kldload dm
kldunload dm
done

===== b.sh
#!/usr/local/bin/bash
kldload dm
while [ 1 ]; do
dmsetup create zero1 --table '0 100 zero'
dmsetup remove /dev/mapper/zero1
done

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sys/dev/disk/dm: Rename aprint_debug() to dmdebug()

Not sure what aprint is, but dmdebug() is better considering
this macro does
if (dm_debug_level) kprintf(...);

sys/dev/disk/dm: Add dm_alloc_string()

Add dm_alloc_string() which kmallocs char* from M_DM.

It was confusing that targets had to use M_DM for status
purpose while targets had their own M_DMXXX. Us

sys/dev/disk/dm: Add dm_alloc_string()

Add dm_alloc_string() which kmallocs char* from M_DM.

It was confusing that targets had to use M_DM for status
purpose while targets had their own M_DMXXX. Using this
wrapper function makes target code less error prone when
allocating a string without an extra comment on usage.

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sys/dev/disk/dm: Remove redundant kprintf in dm strategy

Having two kprintf("------...\n"); before and after debug
messages is redundant since they mostly end up printing
two consecutive lines. One

sys/dev/disk/dm: Remove redundant kprintf in dm strategy

Having two kprintf("------...\n"); before and after debug
messages is redundant since they mostly end up printing
two consecutive lines. One of them could be removed.

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sys/dev/disk/dm: Change table SLIST to TAILQ

TAILQ is more flexible and better for what it's trying to do.

sys/dev/disk/dm: Remove unnecessary ()

sys/dev/disk/dm: Remove aprint_normal()

This is a macro for kprintf, but dm and targets basically
never use this except for a few. There isn't really any
point to keep macro version of kprintf, so g

sys/dev/disk/dm: Remove aprint_normal()

This is a macro for kprintf, but dm and targets basically
never use this except for a few. There isn't really any
point to keep macro version of kprintf, so get rid of it.

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sys/dev/disk/dm: Don't expose cmd_function in header

This struct is necessary only for core part of ioctl where
it needs to translate C string to an appropriate handler.
It just doesn't need to expo

sys/dev/disk/dm: Don't expose cmd_function in header

This struct is necessary only for core part of ioctl where
it needs to translate C string to an appropriate handler.
It just doesn't need to expose everything in dm.h.

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sys/dev/disk/dm: Remove NULL element for array termination

sys/dev/disk/dm: Remove dm_get_version_ioctl()

"version" command is done by userspace (Linux lvm2),
so we really don't need to have any handler for this.

sys/dev/disk/dm: Cleanup DIOCGPART related code

sys/dev/disk/dm: Refactor dmioctl()

Get rid of if-nest and goto.
This function can be implemented without if-nest and goto,
and this is way easier to understand without lots of comments.

sys/dev/disk/dm: Remove unused prototype and wrong comments

sys/dev/disk/dm: Fix typos/etc in kprintf

* Fix typos
* Add missing \n
* Remove \n from \n\n
* Remove unnecessary ' '

sys/dev/disk/dm: Conform to style(9)