actually is an mbuf to process. This catches the missing mbuf before it
would otherwise causes a NULL pointer dereference, which could be
triggered by a 0 length RPC record before the check for such records was
added in rev 1.97.
Approved by: cperciva (mentor)
directory. vrele() may lock the passed vnode, which in these cases would
give an invalid lock order of child -> parent. These situations are
deadlock prone although do not typically deadlock because the vrele
is typically not releasing the last reference to the vnode. Users of
vrele must consider it as a call to vn_lock() and order it appropriately.
MFC After: 1 week
Sponsored by: Isilon Systems, Inc.
Tested by: kkenn
kern_prot.c. This API handles reference counting among many other things.
Notably, if MAC is compiled into the kernel, it will properly initialize the
MAC labels when the ucred is allocated.
This work is in preparation for a new MAC entry point which will be responsible
for properly initializing policy specific labels for the NFS server credential.
Utilization of the crfree/crget APIs reduce the complexity associated with
this label's management.
Submitted by: green (with changes) [1]
Obtained from: TrustedBSD Project
Discussed with: rwatson, alfred
[1] I moved the ucred allocation outside the scope of the NFS server lock to
prevent M_WAIKOK allocations from occurring with non-sleep-able locks held.
Additionally, to reduce complexity, the ucred persist as long as the NFS
server descriptor.
- Prefer '_' to ' ', as it results in more easily parsed results in
memory monitoring tools such as vmstat.
- Remove punctuation that is incompatible with using memory type names
as file names, such as '/' characters.
- Disambiguate some collisions by adding subsystem prefixes to some
memory types.
- Generally prefer lower case to upper case.
- If the same type is defined in multiple architecture directories,
attempt to use the same name in additional cases.
Not all instances were caught in this change, so more work is required to
finish this conversion. Similar changes are required for UMA zone names.
to see if additional write requests will arrive that can be coalesced and
clustered with earlier ones. When doing so, it must determine whether
the two requests are made by credentials with the same access writes, so
as not to coalesce improperly. NFSW_SAMECRED() implements a test of two
credentials using a binary compare.
Replace NFSW_SAMECRED() macro with nfsrv_samecred() function, which is
aware of the contents and layout of a struct ucred, rather than a simple
binary compare. While the binary compare works when ucred is simply a
zero'd and embedded 'struct ucred' in the NFS descriptor, it will work
less well when the ucred associated with an NFS descriptor is "real", so
has defined and populated reference count, mutex, etc.
MFC after: 1 week
Obtained from: TrustedBSD Project
zero'ing their length (copied from m_adj where this code came from
after the equivalent change there has had time to soak)
Noticed by: Coverity Prevent analysis tool
I'm not sure why a credential was added to these in the first place, it is
not used anywhere and it doesn't make much sense:
The credentials for syncing a file (ability to write to the
file) should be checked at the system call level.
Credentials for syncing one or more filesystems ("none")
should be checked at the system call level as well.
If the filesystem implementation needs a particular credential
to carry out the syncing it would logically have to the
cached mount credential, or a credential cached along with
any delayed write data.
Discussed with: rwatson
be made holding the NFS server mutex. To clean this up, introduce a
version of the function, nfsrv_access_withgiant(), that expects the
NFS server mutex to already have been dropped and Giant acquired.
Wrap nfsrv_access() around this. This permits callers to more
efficiently check access if they're in a code block performing VFS
operations, and can be substitited for the nfsrv_access() call that
triggered this bug.
PR: 73807, 73208
MFC after: 1 week
Initialize b_bufobj for all buffers.
Make incore() and gbincore() take a bufobj instead of a vnode.
Make inmem() local to vfs_bio.c
Change a lot of VI_[UN]LOCK(bp->b_vp) to BO_[UN]LOCK(bp->b_bufobj)
also VI_MTX() to BO_MTX(),
Make buf_vlist_add() take a bufobj instead of a vnode.
Eliminate other uses of bp->b_vp where bp->b_bufobj will do.
Various minor polishing: remove "register", turn panic into KASSERT,
use new function declarations, TAILQ_FOREACH_SAFE() etc.
failure in the NFS server would result in a leaked instance of the NFS
server subsystem lock. Liberally sprinkle assertions in all target
labels for error unwinding to assert the desired locking state.
RELENG_5_3 candidate.
MFC after: 3 days
Reported by: Wilkinson, Alex <alex dot wilkinson at dsto dot defence dot gov dot au>
prevent leakage of Giant. With INVARIANTS, this results in an
assertion failure following execution of the RPC. Without INVARIANTS,
it could result in problems if the NFS server is killed causing nfsd
to return to user space holding Giant.
Feet provided by: brueffer
for unknown events.
A number of modules return EINVAL in this instance, and I have left
those alone for now and instead taught MOD_QUIESCE to accept this
as "didn't do anything".
to dup_sockaddr() was renamed to sodupsockaddr(), the argument was
changed from '1' to 'M_WAITOK', which changed the semantics. This
resulted in a WITNESS warning about a potential sleep while holding the
NFS server mutex. Now this will no longer happen, restoring a possible
bug present in the original code (setting RC_NAM even though the malloc
to copy the addres may fail). bde observes that the flag names here
should probably not be the same as the malloc flags for name space
reasons.
Bumped into by: kuriyama
- Lock down low hanging fruit use of sb_flags with socket buffer
lock.
- Lock down low hanging fruit use of so_state with socket lock.
- Lock down low hanging fruit use of so_options.
- Lock down low-hanging fruit use of sb_lowwat and sb_hiwat with
socket buffer lock.
- Annotate situations in which we unlock the socket lock and then
grab the receive socket buffer lock, which are currently actually
the same lock. Depending on how we want to play our cards, we
may want to coallesce these lock uses to reduce overhead.
- Convert a if()->panic() into a KASSERT relating to so_state in
soaccept().
- Remove a number of splnet()/splx() references.
More complex merging of socket and socket buffer locking to
follow.
The big lines are:
NODEV -> NULL
NOUDEV -> NODEV
udev_t -> dev_t
udev2dev() -> findcdev()
Various minor adjustments including handling of userland access to kernel
space struct cdev etc.
Add two additional pairs of assertions, one at the end of the NFS
server event loop, and one one exit from the NFS daemon, that
assert that if debug.mpsafenet is enabled, Giant is not held, and
that if it is not enabled, Giant will be held. This is intended
to support debugging scenarios where Giant is "leaked" during NFS
processing.
install nfssvc(). It also updates the argument count, but did so
without setting SYF_MPSAFE, effectively removing the MPSAFE flag even
when syscalls.master indicates it doesn't require Giant. This change
forces the modevent to set MPSAFE as a flag to its internal notion of
an argument coutn.
Note: this duplication of information is a bad thing, but is a more
general problem I'm not currently willing to address.
a vnode. Not bumped into with asserts in the main tree because we
run the NFS server with Giant by default. Discovered by inspection.
Complete annotations of Giant acquisition/release to note that it's
only because of VFS that we acquire Giant in most places in the NFS
server.
subsystem lock to avoid tripping over an assertion regarding whether
the lock is held or not. This is likely to be the cause of a panic
tripped over by Andrea Campi.
mechanism so that early processing on mbufs can be performed before
a context switch to the NFS server threads. Because of this, if
the socket code is running without Giant, the NFS server also needs
to be able to run the upcall code without relying on the presence on
Giant. This change modifies the NFS server to run using a "giant
code lock" covering operation of the whole subsystem. Work is in
progress to move to data-based locking as part of the NFSv4 server
changes.
Introduce an NFS server subsystem lock, 'nfsd_mtx', and a set of
macros to operate on the lock:
NFSD_LOCK_ASSERT() Assert nfsd_mtx owned by current thread
NFSD_UNLOCK_ASSERT() Assert nfsd_mtx not owned by current thread
NFSD_LOCK_DONTCARE() Advisory: this function doesn't care
NFSD_LOCK() Lock nfsd_mtx
NFSD_UNLOCK() Unlock nfsd_mtx
Constify a number of global variables/structures in the NFS server
code, as they are not modified and contain constants only:
nfsrvv2_procid nfsrv_nfsv3_procid nonidempotent
nfsv2_repstat nfsv2_type nfsrv_nfsv3_procid
nfsrvv2_procid nfsrv_v2errmap nfsv3err_null
nfsv3err_getattr nfsv3err_setattr nfsv3err_lookup
nfsv3err_access nfsv3err_readlink nfsv3err_read
nfsv3err_write nfsv3err_create nfsv3err_mkdir
nfsv3err_symlink nfsv3err_mknod nfsv3err_remove
nfsv3err_rmdir nfsv3err_rename nfsv3err_link
nfsv3err_readdir nfsv3err_readdirplus nfsv3err_fsstat
nfsv3err_fsinfo nfsv3err_pathconf nfsv3err_commit
nfsrv_v3errmap
There are additional structures that should be constified but due
to their being passed into general purpose functions without const
arguments, I have not yet converted.
In general, acquire nfsd_mtx when accessing any of the global NFS
structures, including struct nfssvc_sock, struct nfsd, struct
nfsrv_descript.
Release nfsd_mtx whenever calling into VFS, and acquire Giant for
calls into VFS. Giant is not required for any part of the
operation of the NFS server with the exception of calls into VFS.
Giant will never by acquired in the upcall code path. However, it
may operate entirely covered by Giant, or not. If debug.mpsafenet
is set to 0, the system calls will acquire Giant across all
operations, and the upcall will assert Giant. As such, by default,
this enables locking and allows us to test assertions, but should not
cause any substantial new amount of code to be run without Giant.
Bugs should manifest in the form of lock assertion failures for now.
This approach is similar (but not identical) to modifications to the
BSD/OS NFS server code snapshot provided by BSDi as part of their
SMPng snapshot. The strategy is almost the same (single lock over
the NFS server), but differs in the following ways:
- Our NFS client and server code bases don't overlap, which means
both fewer bugs and easier locking (thanks Peter!). Also means
NFSD_*() as opposed to NFS_*().
- We make broad use of assertions, whereas the BSD/OS code does not.
- Made slightly different choices about how to handle macros building
packets but operating with side effects.
- We acquire Giant only when entering VFS from the NFS server daemon
threads.
- Serious bugs in BSD/OS implementation corrected -- the snapshot we
received was clearly a work in progress.
Based on ideas from: BSDi SMPng Snapshot
Reviewed by: rick@snowhite.cis.uoguelph.ca
Extensive testing by: kris
FreeBSD, we can have a negative available space value, but the
corresponding fields in the NFS protocol are unsigned. So
trnucate the value to 0 if it's negative, so that the client
doesn't receive absurdly high values.
Tested by: cognet
clock precision on i386. This is a NOP change on i386. But this stops
the mount_nfs units from suddenly changing to units of 1/20 of a second
(vs the normal 1/10 of a second) if HZ is increased.
functions in kern_socket.c.
Rename the "canwait" field to "mflags" and pass M_WAITOK and M_NOWAIT
in from the caller context rather than "1" or "0".
Correct mflags pass into mac_init_socket() from previous commit to not
include M_ZERO.
Submitted by: sam
will not actually be set even though we're calling sosetopt. sosetopt
calls down to a single ctloutput function if the name or level is
implemented by a specific protocol.
Submitted by: pete@isilon.com
short read operations at the end of a file to not have the "eof"
flag set as they should. The problem is that the requested read
count was compared against the rounded-up reply data length instead
of the actual reply data length. This bug appears to have been
introduced in revision 1.78 (June 1999). It causes first-time reads
of certain file sizes (e.g 4094 bytes) to fail with EIO on a RedHat
9.0 NFSv3 client.
MFC after: 1 week
when serving up more than about 32 active files. For details see
section 6.3 (pg 111) of Daniel Ellard and Margo Seltzer, ``NFS
Tricks and Benchmarking Traps'' in the Proceedings of the Usenix
2003 Freenix Track, June 9-14, 2003 pg 101-114.
Obtained from: Daniel Ellard <ellard@eecs.harvard.edu>
Sponsored by: DARPA & NAI Labs.
is not pretty, but it fixes the code so that it no longer violates the
vnode locking rules in the VFS API and doesn't trip any of the locking
assertions enabled by the DEBUG_VFS_LOCKS kernel configuration option.
There is one report that this patch fixed a "locking against myself"
panic on an NFS server that was tripped by a diskless client.
Approved by: re (scottl)
- Add a parameter to vm_pageout_flush() that tells vm_pageout_flush()
whether its caller has locked the vm_object. (This is a temporary
measure to bootstrap vm_object locking.)
- Remove the buftimelock mutex and acquire the buf's interlock to protect
these fields instead.
- Hold the vnode interlock while locking bufs on the clean/dirty queues.
This reduces some cases from one BUF_LOCK with a LK_NOWAIT and another
BUF_LOCK with a LK_TIMEFAIL to a single lock.
Reviewed by: arch, mckusick
pointer types, and remove a huge number of casts from code using it.
Change struct xfile xf_data to xun_data (ABI is still compatible).
If we need to add a #define for f_data and xf_data we can, but I don't
think it will be necessary. There are no operational changes in this
commit.
32k read and write operations on datagram sockets when in fact we
reject requests larger than 16k. It must be the case that virtually
all clients use data sizes of 16k or less for UDP transport (FreeBSD's
client defaults to 8k and never exceeds 16k), as this bug has been
present ever since NFSv3 support was added.
Reported by: Senthil <lihtnes78@netscape.net>
Reviewed by: dillon
Approved by: re
MFC-after: 1 week
system accounting configuration and for nfsd server thread attach.
Policies might use this to protect the integrity or confidentiality
of accounting data, limit the ability to turn on or off accounting,
as well as to prevent inappropriately labeled threads from becoming nfs
server threads.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
nfsm_srvpathsiz. This macro plucks a length out of an rpc request and
verifies that its size does not exceed NFS_MAXPATHLEN. If it does
it generates an ENAMETOOLONG response.
- Use this macro, and the existing nfsm_srvnamsiz macro in two places
where we deal with paths passed in by the client.
This fixes a linux interoperability bug. Linux was sending oversized path
components which would cause us to ignore the request all together. This
causes linux to hang indefinitly while it waits for a response. This
could still happen in other cases where we error out with EBADRPC.
Sponsored by: Isilon Systems, Inc.
Reviewed by: alfred, fabbri@isilon.com, neal@isilon.com
- v_vflag is protected by the vnode lock and is used when synchronization
with VOP calls is needed.
- v_iflag is protected by interlock and is used for dealing with vnode
management issues. These flags include X/O LOCK, FREE, DOOMED, etc.
- All accesses to v_iflag and v_vflag have either been locked or marked with
mp_fixme's.
- Many ASSERT_VOP_LOCKED calls have been added where the locking was not
clear.
- Many functions in vfs_subr.c were restructured to provide for stronger
locking.
Idea stolen from: BSD/OS
a ucred by itself as part of an nfs descriptor, then bzero's the ucred,
fails to initialize the mutex, etc. This is very bad, but I don't have
time to fix it right now. nfsd should instead hold a cred pointer,
and the credential should be properly initialized, probably from a
descendent of a kernel process credential.
system lockups (infinite loops) when a zero-length RPC is received.
Linux clients will sometimes send zero-length RPC requests.
Reorganize the use of recm in the loop.
Cc: security@freebsd.org
Submitted by: Mike Junk <junk@isilon.com>
MFC after: 3 days
methodology similar to the vm_map_entry splay and the VM splay that Alan
Cox is working on. Extensive testing has appeared to have shown no
increase in overhead.
Disadvantages
Dirties more cache lines during lookups.
Not as fast as a hash table lookup (but still N log N and optimal
when there is locality of reference).
Advantages
vnode->v_dirtyblkhd is now perfectly sorted, making fsync/sync/filesystem
syncer operate more efficiently.
I get to rip out all the old hacks (some of which were mine) that tried
to keep the v_dirtyblkhd tailq sorted.
The per-vnode splay tree should be easier to lock / SMPng pushdown on
vnodes will be easier.
This commit along with another that Alan is working on for the VM page
global hash table will allow me to implement ranged fsync(), optimize
server-side nfs commit rpcs, and implement partial syncs by the
filesystem syncer (aka filesystem syncer would detect that someone is
trying to get the vnode lock, remembers its place, and skip to the
next vnode).
Note that the buffer cache splay is somewhat more complex then other splays
due to special handling of background bitmap writes (multiple buffers with
the same lblkno in the same vnode), and B_INVAL discontinuities between the
old hash table and the existence of the buffer on the v_cleanblkhd list.
Suggested by: alc
o Add a mutex (sb_mtx) to struct sockbuf. This protects the data in a
socket buffer. The mutex in the receive buffer also protects the data
in struct socket.
o Determine the lock strategy for each members in struct socket.
o Lock down the following members:
- so_count
- so_options
- so_linger
- so_state
o Remove *_locked() socket APIs. Make the following socket APIs
touching the members above now require a locked socket:
- sodisconnect()
- soisconnected()
- soisconnecting()
- soisdisconnected()
- soisdisconnecting()
- sofree()
- soref()
- sorele()
- sorwakeup()
- sotryfree()
- sowakeup()
- sowwakeup()
Reviewed by: alfred
nfsrv_readdir and nfsrv_readdirplus can return. A client request
containing an over-large `count' field could trigger the "Bad nfs
svc reply" panic in nfs_syscalls.c.
Spotted while trying to reproduce kern/37304, which turned out to
be fixed in FreeBSD a long time ago.
MFC after: 1 week
general cleanup of the API. The entire API now consists of two functions
similar to the pre-KSE API. The suser() function takes a thread pointer
as its only argument. The td_ucred member of this thread must be valid
so the only valid thread pointers are curthread and a few kernel threads
such as thread0. The suser_cred() function takes a pointer to a struct
ucred as its first argument and an integer flag as its second argument.
The flag is currently only used for the PRISON_ROOT flag.
Discussed on: smp@
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>
