Pedro F. Giffuni [Sun, 27 Nov 2016 20:30:09 +0000 (20:30 +0000)]
indent(1): fix regression introduced in r303596.
Multi-line comments are always block comments in KNF. Restore properly,
handling the case when a long one-liner gets wrapped and becomes a
multi-line comment.
- Set IEEE80211_FEXT_SCAN_OFFLOAD flag; firmware can send null data
frames when associated.
- Check IEEE80211_SCAN_ACTIVE scan flag instead of IEEE80211_F_ASCAN
ic flag; the last is never set since r170530.
- Eliminate software scan (net80211) <-> site_survey (driver) race:
* override ic_scan_curchan and ic_scan_mindwell pointers so net80211
will not try to finish scanning automatically;
* inform net80211 about current status via ieee80211_cancel_scan()
and ieee80211_scan_done();
* remove corresponding workaround from rsu_join_bss().
Now the driver can associate to an AP with hidden SSID.
NFSv4 client tracks opens, and the track records are only dropped when
the vnode is inactivated. This contradicts with the nullfs caching
which keeps upper vnode around, as consequence keeping the use
reference to lower vnode.
Add a filesystem flag to request nullfs to not cache when mounted over
that filesystem, and set the flag for nfs v4 mounts.
Reported by: asomers
Reviewed by: rmacklem
Tested by: asomers, rmacklem
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Alan Cox [Sun, 27 Nov 2016 01:42:53 +0000 (01:42 +0000)]
Recursion on the free page queue mutex occurred when UMA needed to allocate
a new page of radix trie nodes to complete a vm_radix_insert() operation
that was requested by vm_page_cache(). Specifically, vm_page_cache()
already held the free page queue lock when UMA tried to acquire it through
a call to vm_page_alloc(). This code path no longer exists, so there is no
longer any reason to allow recursion on the free page queue mutex.
- Defined an abstract NVRAM I/O API (bhnd_nvram_io), decoupling NVRAM/SPROM
parsing from the actual underlying NVRAM data provider (e.g. CFE firmware
devices).
- Defined an abstract NVRAM data API (bhnd_nvram_data), decoupling
higher-level NVRAM operations (indexed lookup, data conversion, etc) from
the underlying NVRAM file format parsing/serialization.
- Implemented a new high-level bhnd_nvram_store API, providing indexed
variable lookup, pending write tracking, etc on top of an arbitrary
bhnd_nvram_data instance.
- Migrated all bhnd(4) NVRAM device drivers to the common bhnd_nvram_store
API.
- Implemented a common bhnd_nvram_val API for parsing/encoding NVRAM
variable values, including applying format-specific behavior when
converting to/from the NVRAM string representations.
- Dropped the now unnecessary bhnd_nvram driver, and moved the
broadcom/mips-specific CFE NVRAM driver out into sys/mips/broadcom.
- Implemented a new nvram_map file format:
- Variable definitions are now defined separately from the SPROM
layout. This will also allow us to define CIS tuple NVRAM
mappings referencing the common NVRAM variable definitions.
- Variables can now be defined within arbitrary named groups.
- Textual descriptions and help information can be defined inline
for both variables and variable groups.
- Implemented a new, compact encoding of SPROM image layout
offsets.
- Source-level (but not build system) support for building the NVRAM file
format APIs (bhnd_nvram_io, bhnd_nvram_data, bhnd_nvram_store) as a
userspace library.
The new compact SPROM image layout encoding is loosely modeled on Apple
dyld compressed LINKEDIT symbol binding opcodes; it provides a compact
state-machine encoding of the mapping between NVRAM variables and the SPROM
image offset, mask, and shift instructions necessary to decode or encode
the SPROM variable data.
The compact encoding reduces the size of the generated SPROM layout data
from roughly 60KB to 3KB. The sequential nature SPROM layout opcode tables
also simplify iteration of the SPROM variables, as it's no longer
neccessary to iterate the full NVRAM variable definition table, but
instead simply scan the SPROM revision's layout opcode table.
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D8645
Mark Johnston [Sat, 26 Nov 2016 21:00:27 +0000 (21:00 +0000)]
Launder VPO_NOSYNC pages upon vnode deactivation.
As of r234483, vnode deactivation causes non-VPO_NOSYNC pages to be
laundered. This behaviour has two problems:
1. Dirty VPO_NOSYNC pages must be laundered before the vnode can be
reclaimed, and this work may be unfairly deferred to the vnlru process
or an unrelated application when the system is under vnode pressure.
2. Deactivation of a vnode with dirty VPO_NOSYNC pages requires a scan of
the corresponding VM object's memq for non-VPO_NOSYNC dirty pages; if
the laundry thread needs to launder pages from an unreferenced such
vnode, it will reactivate and deactivate the vnode with each laundering,
potentially resulting in a large number of expensive scans.
Therefore, ensure that all dirty pages are laundered upon deactivation,
i.e., when all maps of the vnode are removed and all references are
released.
Ian Lepore [Sat, 26 Nov 2016 17:55:46 +0000 (17:55 +0000)]
Add an ethernet0 alias pointing to the /aix/usb/hub/ethernet node. This
is required for u-boot to locate the ethernet node when it's doing fixup
of the mac-address property when the user has overridden the default addr.
In C, strchr(3) returns a char*, whereas C++ defines two overloads:
* const char *strchr(const char*, int)
* char *strchr(char*, int)
Building fdt.cc (with the WITHOUT_GPL_DTC knob set) with libc++ 3.9.0 (imported
in r309124) was failing because libc++ r260377 added the first overload to
string.h, leading to failures such as:
fdt.cc:1638:8: error: cannot initialize a variable of type 'char *' with an
rvalue of type 'const char *'
Just define val as a const char* to fix it.
Upstreamed in https://github.com/davidchisnall/dtc/pull/14
Emmanuel Vadot [Sat, 26 Nov 2016 10:36:48 +0000 (10:36 +0000)]
PLL3 have a fractional mode where an explicit frequency (297Mhz or 270)
can be selected for it. If the desired frequency is one of those two, use
this mode instead of the integer one.
When calculating the PLL3 freq for the dotclock, check if it is a multiple
of the fracional frequencies.
Fix automatic eventtimer hardware selection when ARAT
(APIC-Timer-always-running) is not implemented.
If machine has ncpus >= 8 and non-FSB interrupt routing from HPET,
default HPET eventtimer quality 450 is reduced by 100, i.e. it is
350. On the other hand, LAPIC default quality is 600 and it is reduced
by 200 if ARAT is not reported. We end up with HPET quality 350 <
LAPIC quality 400, despite ARAT is not set. Then, since deep Cx
states are active by default, eventtimer fail.
E.g., on Nehalem Core i7 CPU and X58 chipset, LAPIC only works in
C0/C1/C1E and HPET does not implement FSB mode, which otherwise
requires manual switch to HPET to get working system.
Set LAPIC eventtimer quality to 100 if no ARAT.
While there, do not ignore deadlint TSC mode for LAPIC timer if ARAT
is not implemented. If user manually selected LAPIC eventtimer on
such CPU, there is no reason to not use deadline if available and not
disabled administratively.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Rick Macklem [Fri, 25 Nov 2016 23:28:09 +0000 (23:28 +0000)]
Stop "nfsstat -z" from clearing counts of NFSv4 state structures.
The "-z" option on nfsstats was erroneously zeroing out the counts
of NFSv4 state structures. These counts will normally go back down
to zero as state is released. When zeroed out by "-z", these counts
can go negative. This patch fixes this problem.
Justin Hibbits [Fri, 25 Nov 2016 19:36:27 +0000 (19:36 +0000)]
Add an isync to after mtsrin, required by the MPC750 errata
MPC750 User Manual Errata (rev 1) adds a note to C.4.2.2 noting that mtsr,
mtsrin, and mtmsr all require a isync after the instruction and before data
address translation uses any of the segment registers. This should make FreeBSD
run correctly on the G3 again.
Ed Maste [Fri, 25 Nov 2016 18:57:14 +0000 (18:57 +0000)]
Use explicit 0x200000 instead of MAXPAGESIZE for the amd64 kernel physaddr
MAXPAGESIZE is not well defined by the GNU ld documentation.
Different linkers, and different versions of the same linker, use
different MAXPAGESIZE values. Current versions of GNU gold and LLVM's
lld use 4K. When set to 4K the kernel panics at boot due to an issue
with x86bios.
Here we want the kernel physaddr to be the amd64 superpage size, so use
that value (2MB) explicitly. With this change GNU gold and LLVM lld can
link a working amd64 kernel.
Dimitry Andric [Fri, 25 Nov 2016 18:12:13 +0000 (18:12 +0000)]
Pull in r283060 from upstream llvm trunk (by Hal Finkel):
[PowerPC] Refactor soft-float support, and enable PPC64 soft float
This change enables soft-float for PowerPC64, and also makes
soft-float disable all vector instruction sets for both 32-bit and
64-bit modes. This latter part is necessary because the PPC backend
canonicalizes many Altivec vector types to floating-point types, and
so soft-float breaks scalarization support for many operations. Both
for embedded targets and for operating-system kernels desiring
soft-float support, it seems reasonable that disabling hardware
floating-point also disables vector instructions (embedded targets
without hardware floating point support are unlikely to have Altivec,
etc. and operating system kernels desiring not to use floating-point
registers to lower syscall cost are unlikely to want to use vector
registers either). If someone needs this to work, we'll need to
change the fact that we promote many Altivec operations to act on
v4f32. To make it possible to disable Altivec when soft-float is
enabled, hardware floating-point support needs to be expressed as a
positive feature, like the others, and not a negative feature,
because target features cannot have dependencies on the disabling of
some other feature. So +soft-float has now become -hard-float.
Fixes PR26970.
Pull in r283061 from upstream clang trunk (by Hal Finkel):
[PowerPC] Enable soft-float for PPC64, and +soft-float -> -hard-float
Enable soft-float support on PPC64, as the backend now supports it.
Also, the backend now uses -hard-float instead of +soft-float, so set
the target features accordingly.
John Baldwin [Fri, 25 Nov 2016 18:02:43 +0000 (18:02 +0000)]
Permit timed sleeps for threads other than thread0 before timers are working.
The callout subsystem already handles early callouts and schedules
the first clock interrupt appropriately based on the currently pending
callouts. The one nit to fix was that callouts scheduled via C_HARDCLOCK
during early boot could fire too early once timers were enabled as the
per-CPU base time is always zero until timers are initialized. The change
in callout_when() handles this case by using the current uptime as the
base time of the callout during bootup if the per-CPU base time is zero.
Fabien Thomas [Fri, 25 Nov 2016 14:44:49 +0000 (14:44 +0000)]
IPsec RFC6479 support for replay window sizes up to 2^32 - 32 packets.
Since the previous algorithm, based on bit shifting, does not scale
with large replay windows, the algorithm used here is based on
RFC 6479: IPsec Anti-Replay Algorithm without Bit Shifting.
The replay window will be fast to be updated, but will cost as many bits
in RAM as its size.
The previous implementation did not provide a lock on the replay window,
which may lead to replay issues.
Fabien Thomas [Fri, 25 Nov 2016 13:49:33 +0000 (13:49 +0000)]
In a dual processor system (2*6 cores) during IPSec throughput tests,
we see a lot of contention on the arc4 lock, used to generate the IV
of the ESP output packets.
The idea of this patch is to split this mutex in order to reduce the
contention on this lock.
Ed Maste [Fri, 25 Nov 2016 13:15:28 +0000 (13:15 +0000)]
Add WITH_LLD_AS_LD build knob
If set it installs LLD as /usr/bin/ld. LLD (as of version 3.9) is not
capable of linking the world and kernel, but can self-host and link many
substantial applications. GNU ld continues to be used for the world and
kernel build, regardless of how this knob is set.
It is on by default for arm64, and off for all other CPU architectures.
Dimitry Andric [Thu, 24 Nov 2016 22:54:55 +0000 (22:54 +0000)]
Upgrade our copies of clang, llvm, lldb, compiler-rt and libc++ to 3.9.0
release, and add lld 3.9.0. Also completely revamp the build system for
clang, llvm, lldb and their related tools.
Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.
Release notes for llvm, clang and lld are available here:
<http://llvm.org/releases/3.9.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.9.0/tools/clang/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.9.0/tools/lld/docs/ReleaseNotes.html>
Thanks to Ed Maste, Bryan Drewery, Andrew Turner, Antoine Brodin and Jan
Beich for their help.
virtio_console: handle short writes to an Unix domain socket gracefully.
writev() can do a short write. Retrying it results in a very convoluted
and complex code, so we iterate over iovec and do regular stream_write()
instead.
Andriy Gapon [Thu, 24 Nov 2016 21:32:04 +0000 (21:32 +0000)]
virtio_pci: fix announcement of MSI-X interrupts for queues
Queues that do not need interrupts - for instance, output queues - do
not have a corresponding entry in vtpci_msix_vq_interrupts.
So, it was wrong to increment a pointer into that array when iterating
over such a queue.
I ran into this bug while trying to use virtio_console(4) that allocates
a lot of queues with every other being an output queue without an
interrupt handler (if MultiplePorts feature is negotiated).
Justin Hibbits [Thu, 24 Nov 2016 20:31:46 +0000 (20:31 +0000)]
Fix the build post-r309017 for MPC85XX/MPC85XXSPE
r309017 removed two fields from struct vmmeter, which is embedded in struct
pcpu. This caused the struct size to change, triggering the CTASSERT in
sys/pcpu.h. Add the extra 8 bytes back in as padding.
Add a warning against modifying this code without understanding it, and
an example of how not to make it more portable. I've had this lying
around uncommitted since 2009...
https://www.illumos.org/issues/7181
zfsvfs_setup() is called in both zfs_mount and zfs_resume_fs paths.
dmu_objset_set_user(zfsvfs->z_os, zfsvfs) is called early in zfsvfs_setup()
before the setup is actually completed,
thus an under-constructed zfsvfs becomes visible.
Additionally, there is nothing to serialize the two call paths. As a result two
threads can step on each other's toes.
assertion failed: zilog->zl_clean_taskq == NULL, file:
../../common/fs/zfs/zil.c, line: 1772
https://www.illumos.org/issues/7199
dsl_dataset_rollback_sync may try to free already freed blocks when it calls
dsl_destroy_head_sync_impl to destroy a temporary clone.
That happens if a snapshot to which we are rolling back and from which the
clone is created has some ZIL records.
https://www.illumos.org/issues/7200
No new blocks must be born in a dataset in the same TXG after a snapshot of the
dataset is taken.
Those blocks would have the same blk_birth as the dataset's ds_prev_snap_txg
and as such they would be presumed to belong o the snapshot while in fact they
do not.
All the datasets must be clean before sync tasks are run, so the described
scenario may happen only if one of the sync tasks dirties the dataset and
another sync task takes its snapshot.
Then, there will be another sync pass because of the dirty data and the new
blocks will be born in the same TXG when the data is written out.
It seems that almost all of the existing sync tasks modify only MOS and do not
dirty any objsets.
The only exception that I've been able to identify so far is the rollback which
can modify an objset when it zeroes out the objset's ZIL.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Approved by: Gordon Ross <gordon.w.ross@gmail.com>
Author: Andriy Gapon <andriy.gapon@clusterhq.com>
https://www.illumos.org/issues/7180
If a filesystem is not unmounted while the rename is being performed, then, for
example, a concurrect zfs rollback may call zfs_suspend_fs followed by
zfs_resume_fs on the same filesystem.
The latter takes the filesystem's name as an argument. If the filesystem name
changes as a result of the rename, then dmu_objset_hold(osname, zfsvfs, &os)
call in zfs_resume_fs would fail resulting in a kernel panic.
So far I have been able to reproduce this problem on FreeBSD where zfs rename
has -u option that skips the unmounting before doing the renaming.
But I think that in theory the same problem can occur on illumos as well,
because the unmounting is done in userland before invoking the rename ioctl and
there could be a race with, e.g., zfs mount.
panic: solaris assert: dmu_objset_hold(osname, zfsvfs, &zfsvfs->z_os) == 0 (0x2
== 0x0), file: /usr/devel/svn/head/sys/cddl/contrib/opensolaris/uts/common/fs/
zfs/zfs_vfsops.c, line: 2210
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe004df30710
vpanic() at vpanic+0x182/frame 0xfffffe004df30790
panic() at panic+0x43/frame 0xfffffe004df307f0
assfail3() at assfail3+0x2c/frame 0xfffffe004df30810
zfs_resume_fs() at zfs_resume_fs+0xb9/frame 0xfffffe004df30860
zfs_ioc_rollback() at zfs_ioc_rollback+0x61/frame 0xfffffe004df308a0
zfsdev_ioctl() at zfsdev_ioctl+0x65c/frame 0xfffffe004df30940
devfs_ioctl_f() at devfs_ioctl_f+0x156/frame 0xfffffe004df309a0
kern_ioctl() at kern_ioctl+0x246/frame 0xfffffe004df30a00
sys_ioctl() at sys_ioctl+0x171/frame 0xfffffe004df30ae0
amd64_syscall() at amd64_syscall+0x2db/frame 0xfffffe004df30bf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe004df30bf0
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Andriy Gapon [Thu, 24 Nov 2016 09:47:56 +0000 (09:47 +0000)]
firewire: initialize tag label to -1 in fw_xfer_alloc()
Zero can be confused for a potentially valid value.
For example, if I load and unload sbp driver I get a lot of messages
like the following:
fw_tl_free: the xfer is not in the queue (tlabel=0, flag=0x0)
send: dst=0x00 tl=0x00 rt=0 tcode=0x0 pri=0x0 src=0x000
recv: dst=0x01 tl=0x21 rt=1 tcode=0x1 pri=0x0 src=0xffc0
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe04464407e0
fw_tl_free() at fw_tl_free+0x18d/frame 0xfffffe0446440820
fw_xfer_unload() at fw_xfer_unload+0xca/frame 0xfffffe0446440840
fw_xferlist_remove() at fw_xferlist_remove+0x2f/frame 0xfffffe0446440870
sbp_detach() at sbp_detach+0x1e0/frame 0xfffffe04464408e0
device_detach() at device_detach+0x80/frame 0xfffffe0446440900
devclass_driver_deleted() at devclass_driver_deleted+0x6a/frame 0xfffffe0446440940
devclass_delete_driver() at devclass_delete_driver+0x7d/frame 0xfffffe0446440980
driver_module_handler() at driver_module_handler+0xff/frame 0xfffffe04464409d0
module_unload() at module_unload+0x32/frame 0xfffffe04464409f0
linker_file_unload() at linker_file_unload+0x24b/frame 0xfffffe0446440a40
kern_kldunload() at kern_kldunload+0xbc/frame 0xfffffe0446440a70
amd64_syscall() at amd64_syscall+0x314/frame 0xfffffe0446440bf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0446440bf0
Andriy Gapon [Thu, 24 Nov 2016 09:43:42 +0000 (09:43 +0000)]
fwohci: report whether PhysicalUpperBound register is implemented
Please see section 5.15 of 1394 OHCI Specification.
If the register is not implemented, then the physical response unit is
limited to the first 4GB of the physical memory.
In that case the non-cooperative debugging over firewire (using /dev/fwmem)
can not be expected to work if a target has more RAM than that.
The method is described in gdb.4 and the Developer's Handbook.
It seems that most of the consumer hardware does not implement
PhysicalUpperBound register.
Sepherosa Ziehau [Thu, 24 Nov 2016 07:35:16 +0000 (07:35 +0000)]
hyperv/hn: Fix primary channel revocation
Since hypervisor will not drain the TX bufring, once the channels are
revoked:
- Setup vmbus orphan handler properly.
- Make sure that suspension will not wait the TX bufring draining
forever.
- GC the pending TX descs on detach path, before freeing the busdma
stuffs.
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8559
Sepherosa Ziehau [Thu, 24 Nov 2016 06:01:29 +0000 (06:01 +0000)]
hyperv/vmbus: Fix the multi-channel revoking on vmbus side.
- Reference count the sub-channel when channel offer message is
processed, so that immediate rescind message on the same channel
will not race sub-channel open on driver side.
- Drop the above reference when sub-channel is closed, this closely
mimics the hypervisor's reaction when primary channel is closed
on the VM side. No drivers use sub-channel after primary channel
is closed.
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8546
Dexuan Cui [Thu, 24 Nov 2016 05:52:28 +0000 (05:52 +0000)]
share/man/man4/Makefile: Only install Hyper-V man pages on amd64 and i386
We shouldn't install them on the architectures not supported by Hyper-V.
And, hv_ata_pci_disengage.4.gz should be removed from all architectures:
1) It should have only applied to Hyper-V;
2) For Hyper-V platforms (amd64 and i386), the related driver was removed by
r306426 | sephe | 2016-09-29 09:41:52 +0800 (Thu, 29 Sep 2016),
because now we have a better mechanism to disble the ata driver for hard
disks when the VM runs on Hyper-V.
Reviewed by: sephe, andrew, jhb
Approved by: sephe (mentor)
MFC after: 3 days
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8572
Sepherosa Ziehau [Thu, 24 Nov 2016 05:18:45 +0000 (05:18 +0000)]
hyperv/vmbus: Fix the primary channel revoking on vmbus side.
Drivers can now use vmbus_chan_{is_revoked,set_orphan,unset_orphan}() and
vmbus_xact_ctx_orphan() to fix their attach/detach DEVMETHODs for revoked
primary channels.
MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8545
[rpi3] Move SOC_BRCM_BCM2837 from UP config to SMP one
Now that BCM283x source are buildable with SMP option it cam be moved to
GENERIC SMP config. SMP itself does not work on RPi3 yet due to lack of
PSCI monitor which is work in progress at the moment
John Baldwin [Wed, 23 Nov 2016 20:21:53 +0000 (20:21 +0000)]
Fix _mips_rtld_bind() to handle ELF filters.
MIPS does not use the common _rtld_bind() to handle runtime binding.
Instead, it uses a private _mips_rtld_bind(). Update _mips_rtld_bind()
to include the changes made to _rtld_bind() in r216695 and r218476 to
support upgrading the read-locked rtld_bind_lock to a write lock when
an object with a filter is encountered.
While here, add a 'where' variable to track the location of the fixup
in the GOT to make the code flow more closely match _rtld_bind().
Mateusz Guzik [Wed, 23 Nov 2016 19:50:12 +0000 (19:50 +0000)]
cache: ensure that the number of bucket locks does not exceed hash size
The size can be changed by side effect of modifying kern.maxvnodes.
Since numbucketlocks was not modified, setting a sufficiently low value
would give more locks than actual buckets, which would then lead to
corruption.
Emmanuel Vadot [Wed, 23 Nov 2016 18:31:34 +0000 (18:31 +0000)]
Enable UEXT related nodes for Olimex A20 SOM
UEXT are Universal EXTension connector from Olimex. They embed i2c, spi
and uart pins along power in one connector and are found on most,
if not all, Olimex boards.
The Olimex A20 SOM EVB have two UEXT connector so enable the nodes found on
those two connectors.
Patch has been applied upstream, in the meantime add the nodes to our custom
DTS.
Mark Johnston [Wed, 23 Nov 2016 17:53:07 +0000 (17:53 +0000)]
Release laundered vnode pages to the head of the inactive queue.
The swap pager enqueues laundered pages near the head of the inactive queue
to avoid another trip through LRU before reclamation. This change adds
support for this behaviour to the vnode pager and makes use of it in UFS and
ext2fs. Some ioflag handling is consolidated into a common subroutine so
that this support can be easily extended to other filesystems which make use
of the buffer cache. No changes are needed for ZFS since its putpages
routine always undirties the pages before returning, and the laundry
thread requeues the pages appropriately in this case.