locking flags when acquiring a vnode. The immediate purpose is
to allow polling lock requests (LK_NOWAIT) needed by soft updates
to avoid deadlock when enlisting other processes to help with
the background cleanup. For the future it will allow the use of
shared locks for read access to vnodes. This change touches a
lot of files as it affects most filesystems within the system.
It has been well tested on FFS, loopback, and CD-ROM filesystems.
only lightly on the others, so if you find a problem there, please
let me (mckusick@mckusick.com) know.
server side. This can lead to a system deadlock.
Reviewed by: iedowse
Tested by: Alexey G Misurenko <mag@caravan.ru>, iedowse
Bug found with help by: Alexey G Misurenko <mag@caravan.ru>
MFC at: earliest convenience
that va_mode of the supplied attributes is filled in with a valid
file mode (i.e not VNOVAL, and only ALLPERM bits set). However,
some NFS server op functions didn't guarantee this for all possible
request messages:
If a V3 client chose not include to a mode specification, we could
end up creating an ffs inode with mode 0177777, requiring a manual
fsck on the next reboot. Fix this by setting va_mode to 0 before
calling the VOP if a mode hasn't been supplied by the client.
In nfsrv_symlink(), S_IFMT bits supplied by a V2 client could end
up in the va_mode passed to VOP_SYMLINK with similar effects. We
now use the macro nfstov_mode() to correctly mask the bits.
semantics of the nfsm_reply() macro were changed so that the caller
has to explicitly handle the V2 error case, whereas before,
nfsm_reply() did a `goto nfsmout' then. A few server ops (setattr,
readlink, create, mkdir) weren't updated to match, so errors in the
V2 case could cause protocol hangs and leaked mbufs.
Correct some comments that describe the old nfsm_reply behaviour.
[older, harmless nit] Remove the unnecessary `nfsmreply0' label in
nfsrv_create(), since for its users, the main `ereply' label does
the same thing.
but since the nfs cleanup, it hasn't done so in the case where
`error' is EBADRPC. Callers of this macro expect it to initialise
*mrq, and the `nfsmout' exit point expects a reply to be allocated
if error == 0. When nfsm_reply() was called with error = EBADRPC,
whatever junk was in *mrq (often a stale pointer to an old reply
mbuf) would be assumed to be a valid reply and passed to pru_sosend(),
causing a crash sooner or later.
Fix this by allocating a reply even in the EBADRPC case like we
used to do. This bug was specific to -current.
temporary storage. In the old NFS code it wasn't at all clear if
the value of `tl' was used across or after macro calls, but I'm
fairly confident that the convention was to keep its use local.
Each ex-macro function now uses a local version of this variable,
so all of the double-indirection goes away.
The only exception to the `local use' rule for `tl' is nfsm_clget(),
which is left unchanged by this commit.
Reviewed by: peter
out nd.ni_vp to prevent the resource cleanup code at the end of
nfsrv_symlink from trying to vrele it. This fixes a "vrele: negative
ref cnt" panic that can occur when a symlink is attempted on an NFS
filesystem with no free space. Found locally, but the symptoms
correspond to those in the PR referenced below.
PR: kern/26878
MFC after: 3 days
vnodes. This will hopefully serve as a base from which we can
expand the MP code. We currently do not attempt to obtain any
mutex or SX locks, but the door is open to add them when we nail
down exactly how that part of it is going to work.
to do it explicitly in nfsrv_noop so that the reply gets sent back
to the client. This fixes the generation of a selection of RPC
error replies (RPC_PROGMISMATCH, RPC_PROGUNAVAIL, RPC_PROCUNAVAIL
etc.) that are used by some clients to detect support for optional
protocols and features.
Reviewed by: peter
Reported by: Thomas Quinot <quinot@inf.enst.fr>
PR: kern/31479
next to equivalent m_len adjustments. Move the nfsm_subs.h macros
into groups depending on which phase they are used in, since that
affects the error recovery requirements. Collect some of the common error
checking into a single macro as preparation for unwinding some more.
Have nfs_rephead return a value instead of secretly modifying args.
Remove some unused function arguments that were being passed around.
Clarify nfsm_reply()'s error handling (I hope).
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.
Sorry john! (your next MFC will be a doosie!)
Reviewed by: peter@freebsd.org, dillon@freebsd.org
X-MFC after: ha ha ha ha
(this commit is just the first stage). Also add various GIANT_ macros to
formalize the removal of Giant, making it easy to test in a more piecemeal
fashion. These macros will allow us to test fine-grained locks to a degree
before removing Giant, and also after, and to remove Giant in a piecemeal
fashion via sysctl's on those subsystems which the authors believe can
operate without Giant.
vm_mtx does not recurse and is required for most low level
vm operations.
faults can not be taken without holding Giant.
Memory subsystems can now call the base page allocators safely.
Almost all atomic ops were removed as they are covered under the
vm mutex.
Alpha and ia64 now need to catch up to i386's trap handlers.
FFS and NFS have been tested, other filesystems will need minor
changes (grabbing the vm lock when twiddling page properties).
Reviewed (partially) by: jake, jhb
other "system" header files.
Also help the deprecation of lockmgr.h by making it a sub-include of
sys/lock.h and removing sys/lockmgr.h form kernel .c files.
Sort sys/*.h includes where possible in affected files.
OK'ed by: bde (with reservations)
Make the name cache hash as well as the nfsnode hash use it.
As a special tweak, create an unsigned version of register_t. This allows
us to use a special tweak for the 64 bit versions that significantly
speeds up the i386 version (ie: int64 XOR int64 is slower than int64
XOR int32).
The code layout is a little strange for the string function, but I was
able to get between 5 to 10% improvement over the original version I
started with. The layout affects gcc code generation choices and this way
was fastest on x86 and alpha.
Note that 'CPUTYPE=p3' etc makes a fair difference to this. It is
around 45% faster with -march=pentiumpro on a p6 cpu.
actually in the kernel. This structure is a different size than
what is currently in -CURRENT, but should hopefully be the last time
any application breakage is caused there. As soon as any major
inconveniences are removed, the definition of the in-kernel struct
ucred should be conditionalized upon defined(_KERNEL).
This also changes struct export_args to remove dependency on the
constantly-changing struct ucred, as well as limiting the bounds
of the size fields to the correct size. This means: a) mountd and
friends won't break all the time, b) mountd and friends won't crash
the kernel all the time if they don't know what they're doing wrt
actual struct export_args layout.
Reviewed by: bde
of returning an error code to the caller, NFS server op routines
must themselves build an error reply and return 0 to the caller.
This is achieved by replacing the erroneous return statements with
code that jumps forward to the op function's reply code. We need
to be careful to ensure that the 'struct mount' pointer is NULL
though, so that the final vn_finished_write() call becomes a no-op.
Reviewed by: mckusick, dillon
This is because calls with M_WAIT (now M_TRYWAIT) may not wait
forever when nothing is available for allocation, and may end up
returning NULL. Hopefully we now communicate more of the right thing
to developers and make it very clear that it's necessary to check whether
calls with M_(TRY)WAIT also resulted in a failed allocation.
M_TRYWAIT basically means "try harder, block if necessary, but don't
necessarily wait forever." The time spent blocking is tunable with
the kern.ipc.mbuf_wait sysctl.
M_WAIT is now deprecated but still defined for the next little while.
* Fix a typo in a comment in mbuf.h
* Fix some code that was actually passing the mbuf subsystem's M_WAIT to
malloc(). Made it pass M_WAITOK instead. If we were ever to redefine the
value of the M_WAIT flag, this could have became a big problem.
Pre-rfork code assumed inherent locking of a process's file descriptor
array. However, with the advent of rfork() the file descriptor table
could be shared between processes. This patch closes over a dozen
serious race conditions related to one thread manipulating the table
(e.g. closing or dup()ing a descriptor) while another is blocked in
an open(), close(), fcntl(), read(), write(), etc...
PR: kern/11629
Discussed with: Alexander Viro <viro@math.psu.edu>
mail:
The problem seems to originate with NFS's postop_attr
information that is returned with a read or write RPC.
Within a vm_fault context, the code cannot deal with
vnode_pager_setsize() shrinking a vnode.
The workaround in the patch below stops the nfsm_postop_attr()
macro from ever shrinking a vnode. If the new size in the
postop_attr information is smaller, then it just sets the
nfsnode n_attrstamp to 0 to stop the wrong size getting
used in the future. This change only affects postop_attr
attributes; the nfsm_loadattr() macro works as normal.
The change is implemented by adding a new argument to
nfs_loadattrcache() called 'dontshrink'. When this is
non-zero, nfs_loadattrcache() will never reduce the
vnode/nfsnode size; instead it zeros n_attrstamp.
There remain other was processes can get stuck in vmopar.
Submitted by: Ian Dowse <iedowse@maths.tcd.ie>
Reviewed by: dillon
Tested by: Vadim Belman <voland@lflat.org>
include:
* Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The
alpha port is still in transition and currently uses both.)
* Per-CPU idle processes.
* Interrupts are run in their own separate kernel threads and can be
preempted (i386 only).
Partially contributed by: BSDi (BSD/OS)
Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh
with the new snapshot code.
Update addaliasu to correctly implement the semantics of the old
checkalias function. When a device vnode first comes into existence,
check to see if an anonymous vnode for the same device was created
at boot time by bdevvp(). If so, adopt the bdevvp vnode rather than
creating a new vnode for the device. This corrects a problem which
caused the kernel to panic when taking a snapshot of the root
filesystem.
Change the calling convention of vn_write_suspend_wait() to be the
same as vn_start_write().
Split out softdep_flushworklist() from softdep_flushfiles() so that
it can be used to clear the work queue when suspending filesystem
operations.
Access to buffers becomes recursive so that snapshots can recursively
traverse their indirect blocks using ffs_copyonwrite() when checking
for the need for copy on write when flushing one of their own indirect
blocks. This eliminates a deadlock between the syncer daemon and a
process taking a snapshot.
Ensure that softdep_process_worklist() can never block because of a
snapshot being taken. This eliminates a problem with buffer starvation.
Cleanup change in ffs_sync() which did not synchronously wait when
MNT_WAIT was specified. The result was an unclean filesystem panic
when doing forcible unmount with heavy filesystem I/O in progress.
Return a zero'ed block when reading a block that was not in use at
the time that a snapshot was taken. Normally, these blocks should
never be read. However, the readahead code will occationally read
them which can cause unexpected behavior.
Clean up the debugging code that ensures that no blocks be written
on a filesystem while it is suspended. Snapshots must explicitly
label the blocks that they are writing during the suspension so that
they do not cause a `write on suspended filesystem' panic.
Reorganize ffs_copyonwrite() to eliminate a deadlock and also to
prevent a race condition that would permit the same block to be
copied twice. This change eliminates an unexpected soft updates
inconsistency in fsck caused by the double allocation.
Use bqrelse rather than brelse for buffers that will be needed
soon again by the snapshot code. This improves snapshot performance.
the gating of system calls that cause modifications to the underlying
filesystem. The gating can be enabled by any filesystem that needs
to consistently suspend operations by adding the vop_stdgetwritemount
to their set of vnops. Once gating is enabled, the function
vfs_write_suspend stops all new write operations to a filesystem,
allows any filesystem modifying system calls already in progress
to complete, then sync's the filesystem to disk and returns. The
function vfs_write_resume allows the suspended write operations to
begin again. Gating is not added by default for all filesystems as
for SMP systems it adds two extra locks to such critical kernel
paths as the write system call. Thus, gating should only be added
as needed.
Details on the use and current status of snapshots in FFS can be
found in /sys/ufs/ffs/README.snapshot so for brevity and timelyness
is not included here. Unless and until you create a snapshot file,
these changes should have no effect on your system (famous last words).
<sys/bio.h>.
<sys/bio.h> is now a prerequisite for <sys/buf.h> but it shall
not be made a nested include according to bdes teachings on the
subject of nested includes.
Diskdrivers and similar stuff below specfs::strategy() should no
longer need to include <sys/buf.> unless they need caching of data.
Still a few bogus uses of struct buf to track down.
Repocopy by: peter
reserve, in maximal NFS packets. Originally only 2 packets worth of
space was reserved. The default is now 4, which appears to greatly
improve performance for slow to mid-speed machines on gigabit networks.
Add documentation and correct some prior documentation.
Problem Researched by: Andrew Gallatin <gallatin@cs.duke.edu>
Approved by: jkh
substitute BUF_WRITE(foo) for VOP_BWRITE(foo->b_vp, foo)
substitute BUF_STRATEGY(foo) for VOP_STRATEGY(foo->b_vp, foo)
This patch is machine generated except for the ccd.c and buf.h parts.
field in struct buf: b_iocmd. The b_iocmd is enforced to have
exactly one bit set.
B_WRITE was bogusly defined as zero giving rise to obvious coding
mistakes.
Also eliminate the redundant struct buf flag B_CALL, it can just
as efficiently be done by comparing b_iodone to NULL.
Should you get a panic or drop into the debugger, complaining about
"b_iocmd", don't continue. It is likely to write on your disk
where it should have been reading.
This change is a step in the direction towards a stackable BIO capability.
A lot of this patch were machine generated (Thanks to style(9) compliance!)
Vinum users: Greg has not had time to test this yet, be careful.
there is nothing we can do about it. In fact, after further review
there simply are not very many instances of the two structures NFS
checks for 'bloat' so I've decided to simply rip the checks out entirely.
Submitted by: Andrew Gallatin <gallatin@cs.duke.edu>
into vnode dirtyblkhd we append it to the list instead of prepend it to
the list in order to maintain a 'forward' locality of reference, which
is arguably better then 'reverse'. The original algorithm did things this
way to but at a huge time cost.
Enhance the append interlock for NFS writes to handle intr/soft mounts
better.
Fix the hysteresis for NFS async daemon I/O requests to reduce the
number of unnecessary context switches.
Modify handling of NFS mount options. Any given user option that is
too high now defaults to the kernel maximum for that option rather then
the kernel default for that option.
Reviewed by: Alfred Perlstein <bright@wintelcom.net>
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.
NFSSERVER defined, useful for userland fileservers that want to
use a filehandle type interface to the filesystem.
Submitted by: Assar Westerlund assar@stacken.kth.se
PR: kern/15452
generate the NFSv3 Version id. boottime itself may change, sometimes
once every tick if you are running xntpd, which really throws off
clients. Clients will tend to throw away what they believe to be
stale data too often, and can get into long loops rewriting the same
data over and over again because they believe the server has rebooted
over and over again due to the changing version id.
Approved by: jkh
cannot unilaterally pass data to a client it can reduce the physical
disk transaction overhead by reading larger blocks. This results in
better pipelining of requests/responses over the network and an almost
100% increase in cpu efficiency on the server. On a 100BaseTX network
NFS read performance increases from 8.5 MBytes/sec to 10 MB/sec (maxed
out), and cpu efficiency increases from 72% idle to 80% idle on the server.
Reviewed by: Alfred Perlstein <bright@wintelcom.net>
NFS packets, mainly initializing structure pointers to NULL which
are conditionally freed prior to return.
PR: kern/15249
Submitted by: Ian Dowse <iedowse@maths.tcd.ie>
blocks of zeros could wind up in a file written to over NFS by a client.
The problem only occurs a few times per several gigabytes of data. This
problem turned out to be bug #3 below.
bug #1:
B_CLUSTEROK must be cleared when an NFS buffer is reverted from
stage 2 (ready for commit rpc) to stage 1 (ready for write).
Reversions can occur when a dirty NFS buffer is redirtied with new
data.
Otherwise the VFS/BIO system may end up thinking that a stage 1
NFS buffer is clusterable. Stage 1 NFS buffers are not clusterable.
bug #2:
B_CLUSTEROK was inappropriately set for a 'short' NFS buffer (short
buffers only occur near the EOF of the file). Change to only set
when the buffer is a full biosize (usually 8K). This bug has no
effect but should be fixed in -current anyway. It need not be
backported.
bug #3:
B_NEEDCOMMIT was inappropriately set in nfs_flush() (which is
typically only called by the update daemon). nfs_flush()
does a multi-pass loop but due to the lack of vnode locking it
is possible for new buffers to be added to the dirtyblkhd list
while a flush operation is going on. This may result in nfs_flush()
setting B_NEEDCOMMIT on a buffer which has *NOT* yet gone through its
stage 1 write, causing only the commit rpc to be made and thus
causing the contents of the buffer to be thrown away (never sent to
the server).
The patch also contains some cleanup, which only applies to the commit
into -current.
Reviewed by: dg, julian
Originally Reported by: Dan Nelson <dnelson@emsphone.com>
of element [4] in both, which goes beyond the end of the array, leaving
[0], [1], [2], and [3]. This bug did not cause any problems since
the overrun fields are initialized after the bogus array init but
needs to be fixed anyway.
Submitted by: Ian Dowse <iedowse@maths.tcd.ie>
Note: Previous commit to these files (except coda_vnops and devfs_vnops)
that claimed to remove WILLRELE from VOP_RENAME actually removed it from
VOP_MKNOD.
when returning an error. Bug fix was extracted from the PR. The PR
is not yet entirely resolved by this commit.
PR: kern/13049
Reviewed by: Matt Dillon <dillon@freebsd.org>
Submitted by: Ian Dowse <iedowse@maths.tcd.ie>
error for a directory. I have made this change after a great deal of
review although I cannot be absolutely sure that this meets the spec.
The issue devolves into whether changes in an underlying (UFS) directory
can cause NFS directory blocks to be renumbered. My read of the code
indicates that NFS directory blocks will not be renumbered, which means
that the cookies should still remain valid after a change is made to
the underlying directory. This being the case, a cookie error should
not be returned when a change is made to the underlying directory and,
instead, the NFS client should rely on mtime detection to invalidate and
reload the directory.
The use of mtime is problematic in of itself, due to insufficient
resolution, which is why I believe the original conservative error
handling was done. Still, there have been dozens of bug reports by
people needing solaris<->FreeBSD interoperability and these have to
be accomodated.
-----------------------------
The core of the signalling code has been rewritten to operate
on the new sigset_t. No methodological changes have been made.
Most references to a sigset_t object are through macros (see
signalvar.h) to create a level of abstraction and to provide
a basis for further improvements.
The NSIG constant has not been changed to reflect the maximum
number of signals possible. The reason is that it breaks
programs (especially shells) which assume that all signals
have a non-null name in sys_signame. See src/bin/sh/trap.c
for an example. Instead _SIG_MAXSIG has been introduced to
hold the maximum signal possible with the new sigset_t.
struct sigprop has been moved from signalvar.h to kern_sig.c
because a) it is only used there, and b) access must be done
though function sigprop(). The latter because the table doesn't
holds properties for all signals, but only for the first NSIG
signals.
signal.h has been reorganized to make reading easier and to
add the new and/or modified structures. The "old" structures
are moved to signalvar.h to prevent namespace polution.
Especially the coda filesystem suffers from the change, because
it contained lines like (p->p_sigmask == SIGIO), which is easy
to do for integral types, but not for compound types.
NOTE: kdump (and port linux_kdump) must be recompiled.
Thanks to Garrett Wollman and Daniel Eischen for pressing the
importance of changing sigreturn as well.
previously issued synchronously even if async daemons (nfsiod's) were
available. The commit has been moved from the strategy code to the doio
code in order to asynchronize it.
Removed use of lastr in preparation for removal of vnode->v_lastr. It
has been replaced with seqcount, which is already supported by the system
and, in fact, gives us a better heuristic for sequential detection then
lastr ever did.
Made major performance improvements to the server side commit. The
server previously fsync'd the entire file for each commit rpc. The
server now bawrite()s only those buffers related to the offset/size
specified in the commit rpc.
Note that we do not commit the meta-data yet. This works still needs
to be done.
Note that a further optimization can be done (and has not yet been done)
on the client: we can merge multiple potential commit rpc's into a
single rpc with a greater file offset/size range and greatly reduce
rpc traffic.
Reviewed by: Alan Cox <alc@cs.rice.edu>, David Greenman <dg@root.com>
Make the alias list a SLIST.
Drop the "fast recycling" optimization of vnodes (including
the returning of a prexisting but stale vnode from checkalias).
It doesn't buy us anything now that we don't hardlimit
vnodes anymore.
Rename checkalias2() and checkalias() to addalias() and
addaliasu() - which takes dev_t and udev_t arg respectively.
Make the revoke syscalls use vcount() instead of VALIASED.
Remove VALIASED flag, we don't need it now and it is faster
to traverse the much shorter lists than to maintain the
flag.
vfs_mountedon() can check the dev_t directly, all the vnodes
point to the same one.
Print the devicename in specfs/vprint().
Remove a couple of stale LFS vnode flags.
Remove unimplemented/unused LK_DRAINED;
works correctly in if/else etc. egcs had probably picked up most of the
problems here before with "ambiguous braces" etc, but this should
increase the robustness a bit. Based on an idea from Eivind Eklund.
correct the pointers afterwards.
It's kinda bogus that we generate a 24 (?) byte filehandle (2 x int32
fsid and 16 byte VFS fhandle) and pad it out to 64 bytes for NFSv3 with
garbage. The whole point of NFSv3's variable filehandle length was
to allow for shorter handles, both in memory and over the wire. I plan
on taking a shot at fixing this shortly.
being incremented by 4 bytes too few each time through the loop, which
allows more data into the mbuf chain that we really want. In the worst
case, when we're using 32K read/write sizes with a TCP client, this causes
readdirplus replies to sometimes exceed NFS_MAXPACKET which leads to a
panic. This problem cropped up for me using an IRIX 6.5.4 NFSv3 TCP client
with 32K read/write sizes, however supposedly it can be triggered by
WinNT NFS servers too. In theory, it can probably be triggered by any
NFS v3 implementation using TCP as long as it's using the maxiumum block
size.
Reviewed by: Matthew Dillon <dillon@backplane.com>
lockmgr locks. This commit should be functionally equivalent to the old
semantics. That is, all buffer locking is done with LK_EXCLUSIVE
requests. Changes to take advantage of LK_SHARED and LK_RECURSIVE will
be done in future commits.
txdr_hyper and fxdr_hyper tweaks to avoid excessive CPU order knowledge.
nfs_serv.c: don't call nfsm_adj() with negative values, windows clients
could crash servers when doing a readdir of a large directory.
nfs_socket.c: Use IP_PORTRANGE to get a priviliged port without a spin
loop trying to bind(). Don't clobber a mbuf pointer or we get panics
on a NFS3ERR_JUKEBOX error from a server when reusing a freed mbuf.
nfs_subs.c: Don't loose st_blocks on NFSv2 mounts when > 2GB.
Obtained from: OpenBSD
udev_t in the kernel but still called dev_t in userland.
Provide functions to manipulate both types:
major() umajor()
minor() uminor()
makedev() umakedev()
dev2udev() udev2dev()
For now they're functions, they will become in-line functions
after one of the next two steps in this process.
Return major/minor/makedev to macro-hood for userland.
Register a name in cdevsw[] for the "filedescriptor" driver.
In the kernel the udev_t appears in places where we have the
major/minor number combination, (ie: a potential device: we
may not have the driver nor the device), like in inodes, vattr,
cdevsw registration and so on, whereas the dev_t appears where
we carry around a reference to a actual device.
In the future the cdevsw and the aliased-from vnode will be hung
directly from the dev_t, along with up to two softc pointers for
the device driver and a few houskeeping bits. This will essentially
replace the current "alias" check code (same buck, bigger bang).
A little stunt has been provided to try to catch places where the
wrong type is being used (dev_t vs udev_t), if you see something
not working, #undef DEVT_FASCIST in kern/kern_conf.c and see if
it makes a difference. If it does, please try to track it down
(many hands make light work) or at least try to reproduce it
as simply as possible, and describe how to do that.
Without DEVT_FASCIST I belive this patch is a no-op.
Stylistic/posixoid comments about the userland view of the <sys/*.h>
files welcome now, from userland they now contain the end result.
Next planned step: make all dev_t's refer to the same devsw[] which
means convert BLK's to CHR's at the perimeter of the vnodes and
other places where they enter the game (bootdev, mknod, sysctl).
piecemeal, middle-of-file writes for NFS. These hacks have caused no
end of trouble, especially when combined with mmap(). I've removed
them. Instead, NFS will issue a read-before-write to fully
instantiate the struct buf containing the write. NFS does, however,
optimize piecemeal appends to files. For most common file operations,
you will not notice the difference. The sole remaining fragment in
the VFS/BIO system is b_dirtyoff/end, which NFS uses to avoid cache
coherency issues with read-merge-write style operations. NFS also
optimizes the write-covers-entire-buffer case by avoiding the
read-before-write. There is quite a bit of room for further
optimization in these areas.
The VM system marks pages fully-valid (AKA vm_page_t->valid =
VM_PAGE_BITS_ALL) in several places, most noteably in vm_fault. This
is not correct operation. The vm_pager_get_pages() code is now
responsible for marking VM pages all-valid. A number of VM helper
routines have been added to aid in zeroing-out the invalid portions of
a VM page prior to the page being marked all-valid. This operation is
necessary to properly support mmap(). The zeroing occurs most often
when dealing with file-EOF situations. Several bugs have been fixed
in the NFS subsystem, including bits handling file and directory EOF
situations and buf->b_flags consistancy issues relating to clearing
B_ERROR & B_INVAL, and handling B_DONE.
getblk() and allocbuf() have been rewritten. B_CACHE operation is now
formally defined in comments and more straightforward in
implementation. B_CACHE for VMIO buffers is based on the validity of
the backing store. B_CACHE for non-VMIO buffers is based simply on
whether the buffer is B_INVAL or not (B_CACHE set if B_INVAL clear,
and vise-versa). biodone() is now responsible for setting B_CACHE
when a successful read completes. B_CACHE is also set when a bdwrite()
is initiated and when a bwrite() is initiated. VFS VOP_BWRITE
routines (there are only two - nfs_bwrite() and bwrite()) are now
expected to set B_CACHE. This means that bowrite() and bawrite() also
set B_CACHE indirectly.
There are a number of places in the code which were previously using
buf->b_bufsize (which is DEV_BSIZE aligned) when they should have
been using buf->b_bcount. These have been fixed. getblk() now clears
B_DONE on return because the rest of the system is so bad about
dealing with B_DONE.
Major fixes to NFS/TCP have been made. A server-side bug could cause
requests to be lost by the server due to nfs_realign() overwriting
other rpc's in the same TCP mbuf chain. The server's kernel must be
recompiled to get the benefit of the fixes.
Submitted by: Matthew Dillon <dillon@apollo.backplane.com>
This is a seriously beefed up chroot kind of thing. The process
is jailed along the same lines as a chroot does it, but with
additional tough restrictions imposed on what the superuser can do.
For all I know, it is safe to hand over the root bit inside a
prison to the customer living in that prison, this is what
it was developed for in fact: "real virtual servers".
Each prison has an ip number associated with it, which all IP
communications will be coerced to use and each prison has its own
hostname.
Needless to say, you need more RAM this way, but the advantage is
that each customer can run their own particular version of apache
and not stomp on the toes of their neighbors.
It generally does what one would expect, but setting up a jail
still takes a little knowledge.
A few notes:
I have no scripts for setting up a jail, don't ask me for them.
The IP number should be an alias on one of the interfaces.
mount a /proc in each jail, it will make ps more useable.
/proc/<pid>/status tells the hostname of the prison for
jailed processes.
Quotas are only sensible if you have a mountpoint per prison.
There are no privisions for stopping resource-hogging.
Some "#ifdef INET" and similar may be missing (send patches!)
If somebody wants to take it from here and develop it into
more of a "virtual machine" they should be most welcome!
Tools, comments, patches & documentation most welcome.
Have fun...
Sponsored by: http://www.rndassociates.com/
Run for almost a year by: http://www.servetheweb.com/
1:
s/suser/suser_xxx/
2:
Add new function: suser(struct proc *), prototyped in <sys/proc.h>.
3:
s/suser_xxx(\([a-zA-Z0-9_]*\)->p_ucred, \&\1->p_acflag)/suser(\1)/
The remaining suser_xxx() calls will be scrutinized and dealt with
later.
There may be some unneeded #include <sys/cred.h>, but they are left
as an exercise for Bruce.
More changes to the suser() API will come along with the "jail" code.
routine was [ab]used for two different things, and you couldn't tell from
the wait channel which one had wedged.
Catch a few things missing from NFS_NOSERVER.
