sys/dev/ccd.c: Restore historic RCS id.

This got munged accidentally by `git cvsexportcommit -k' -- taking
that option out of my commitbomb script!

driver(9): devsw_detach never fails. Make it return void.

Prune a whole lotta dead branches as a result of this. (Some logic
calling this is also wrong for other reasons; devsw_detach is final
--

driver(9): devsw_detach never fails. Make it return void.

Prune a whole lotta dead branches as a result of this. (Some logic
calling this is also wrong for other reasons; devsw_detach is final
-- you should never have any reason to decide to roll it back. To be
cleaned up in subsequent commits...)

XXX kernel ABI change to devsw_detach signature requires bump

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ccd(4): Only pathbuf_destroy if pathbuf_copyin succeeded.

Reported-by: syzbot+a46aadc788a80afc8742@syzkaller.appspotmail.com

ccd(4): Fix typo in comment.

Fix ioctl locking. Add dkdriver.

uvm_availmem(): give it a boolean argument to specify whether a recent
cached value will do, or if the very latest total must be fetched. It can
be called thousands of times a second and fetching th

uvm_availmem(): give it a boolean argument to specify whether a recent
cached value will do, or if the very latest total must be fetched. It can
be called thousands of times a second and fetching the totals impacts not
only the calling LWP but other CPUs doing unrelated activity in the VM
system.

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Rename uvm_free() -> uvm_availmem().

uvmexp.free -> uvm_free()

Switch to vn_bdev_open* functions.

Many years ago someone created a new __link_set_sysctl_funcs to hold
the list of routines that need to be called for setting up sysctl
variables. This worked great for all code included in the kerne

Many years ago someone created a new __link_set_sysctl_funcs to hold
the list of routines that need to be called for setting up sysctl
variables. This worked great for all code included in the kernel
itself, but didn't deal with modules that want to create their own
sysctl data. So, we ended up with a lot of #ifdef _MODULE blocks
so modules could explicitly call their setup functions when loaded
as non-built-in modules.

So today, we complete the task that was started so many years ago.

When modules are loaded, after we've called xxx_modcmd(INIT...) we
check if the module contains its own __link_set_sysctl_funcs, and
if so we call the functions listed. We add a struct sysctllog member
to the struct module so we can call sysctl_teardown() when the module
gets unloaded. (The sequence of events ensures that the sysctl stuff
doesn't get created until the rest of the module's init code does any
required memory allocation.)

So, no more need to explicitly call the sysctl setup routines when
built as a loadable module.

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Add a disk ioctl DIOCRMWEDGES to remove all wedges of a given disk
(if not busy).

Rename the MODULE_*_HOOK() macros to MODULE_HOOK_*() as briefly
discussed on irc.

NFCI intended.

Ride the earlier kernel bump - it;s getting crowded.

Merge the [pgoyette-compat] branch

factor out the ccd COMPAT_60 code.

Add "bufq_fcfs" requirement to all those driver modules that explicitly
request it in their calls to bufq_alloc().

Ooppss, need an ampersand call calling LIST_EMPTY() macro

There is currently a counter nactive which tracks the INSERT and REMOVE
of entries in the ccds LIST.

Since the counter is checked only when the ccd module is being unloaded,
remove the counter compl

There is currently a counter nactive which tracks the INSERT and REMOVE
of entries in the ccds LIST.

Since the counter is checked only when the ccd module is being unloaded,
remove the counter completely and just check for LIST_EMPTY(ccds).

No functional change intended.

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remove checks for failure after memory allocation calls that cannot fail:

kmem_alloc() with KM_SLEEP
kmem_zalloc() with KM_SLEEP
percpu_alloc()
pserialize_create()
psref_class_create()

al

remove checks for failure after memory allocation calls that cannot fail:

kmem_alloc() with KM_SLEEP
kmem_zalloc() with KM_SLEEP
percpu_alloc()
pserialize_create()
psref_class_create()

all of these paths include an assertion that the allocation has not failed,
so callers should not assert that again.

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introduce DKCACHE_COMBINE() macro - it combines the flags in a way that
all common flags are retained, and flags regarding write cache are preserved
if either of the devices has it; callers can thus

introduce DKCACHE_COMBINE() macro - it combines the flags in a way that
all common flags are retained, and flags regarding write cache are preserved
if either of the devices has it; callers can thus rely on write cache not
being possible to be used when both flags are missing

use the new macro for ccd(4)

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support DIOCGCACHE - result is intersection of flags returned by underlying
devices; devices can't be added or removed, so the feature flags remain
static

add support for DIOCGSTRATEGY while here, m

support DIOCGCACHE - result is intersection of flags returned by underlying
devices; devices can't be added or removed, so the feature flags remain
static

add support for DIOCGSTRATEGY while here, mainly to make dkctl(8) output neater

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Enhance disk metrics by calculating a weighted sum that is incremented
by the number of concurrent I/O requests. Also introduce a new disk_wait()
function to measure requests waiting in a bufq.
iosta

Enhance disk metrics by calculating a weighted sum that is incremented
by the number of concurrent I/O requests. Also introduce a new disk_wait()
function to measure requests waiting in a bufq.
iostat -y now reports data about waiting and active requests.

So far only drivers using dksubr and dk, ccd, wd and xbd collect data about
waiting requests.

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Avoid calling bufq_free() from critical section.

Create the kern.ccd sysctl sub-tree when built as a module. Even though
the contents of the sub-tree are all structures, and thus not displayed
via sysctl(8), the info is potentially useful to progr

Create the kern.ccd sysctl sub-tree when built as a module. Even though
the contents of the sub-tree are all structures, and thus not displayed
via sysctl(8), the info is potentially useful to programs. (For example,
ccdconfig could use this to determine how many units are available.)

The sub-tree is already available when the module is included as built-in
module.

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Replace DIOCGPART -> DIOCGPARTINFO which returns the data needed instead of
pointers.

include "ioconf.h" to get the 'void <driver>attach(int count);' prototype.