Commit Graph

176 Commits

Author SHA1 Message Date
John Baldwin
5055536eec Use the VA_UTIMES_NULL flag to detect when NULL was passed to utimes()
instead of comparing the desired time against the current time as a
heuristic.

Reviewed by:	rmacklem
MFC after:	1 week
2013-01-16 21:52:31 +00:00
Gleb Smirnoff
eb1b1807af Mechanically substitute flags from historic mbuf allocator with
malloc(9) flags within sys.

Exceptions:

- sys/contrib not touched
- sys/mbuf.h edited manually
2012-12-05 08:04:20 +00:00
Kirk McKusick
550da26ab1 Fix mount mutex handling missed in r234386. 2012-05-10 21:38:48 +00:00
Kirk McKusick
71469bb38f Replace the MNT_VNODE_FOREACH interface with MNT_VNODE_FOREACH_ALL.
The primary changes are that the user of the interface no longer
needs to manage the mount-mutex locking and that the vnode that
is returned has its mutex locked (thus avoiding the need to check
to see if its is DOOMED or other possible end of life senarios).

To minimize compatibility issues for third-party developers, the
old MNT_VNODE_FOREACH interface will remain available so that this
change can be MFC'ed to 9. Following the MFC to 9, MNT_VNODE_FOREACH
will be removed in head.

The reason for this update is to prepare for the addition of the
MNT_VNODE_FOREACH_ACTIVE interface that will loop over just the
active vnodes associated with a mount point (typically less than
1% of the vnodes associated with the mount point).

Reviewed by: kib
Tested by:   Peter Holm
MFC after:   2 weeks
2012-04-17 16:28:22 +00:00
John Baldwin
5aefb4cbbf Close a race in NFS lookup processing that could result in stale name cache
entries on one client when a directory was renamed on another client.  The
root cause for the stale entry being trusted is that each per-vnode nfsnode
structure has a single 'n_ctime' timestamp used to validate positive name
cache entries.  However, if there are multiple entries for a single vnode,
they all share a single timestamp.  To fix this, extend the name cache
to allow filesystems to optionally store a timestamp value in each name
cache entry.  The NFS clients now fetch the timestamp associated with
each name cache entry and use that to validate cache hits instead of the
timestamps previously stored in the nfsnode.  Another part of the fix is
that the NFS clients now use timestamps from the post-op attributes of
RPCs when adding name cache entries rather than pulling the timestamps out
of the file's attribute cache.  The latter is subject to races with other
lookups updating the attribute cache concurrently.  Some more details:
- Add a variant of nfsm_postop_attr() to the old NFS client that can return
  a vattr structure with a copy of the post-op attributes.
- Handle lookups of "." as a special case in the NFS clients since the name
  cache does not store name cache entries for ".", so we cannot get a
  useful timestamp.  It didn't really make much sense to recheck the
  attributes on the the directory to validate the namecache hit for "."
  anyway.
- ABI compat shims for the name cache routines are present in this commit
  so that it is safe to MFC.

MFC after:	2 weeks
2012-01-20 20:02:01 +00:00
Rick Macklem
1f3765902c Change the sysctl naming for the old and new NFS clients
to vfs.oldnfs.xxx and vfs.nfs.xxx respectively. This makes
the default nfs client use vfs.nfs.xxx after r221124.
2011-05-15 20:52:43 +00:00
Rick Macklem
f9de8782aa Move sys/nfsclient/nfs_kdtrace.h to sys/nfs/nfs_kdtrace.h so
it can be used by the new NFS client as well as the old one.
2011-05-06 20:02:19 +00:00
Ruslan Ermilov
be4e2e7570 - Fixed nfs_printf() to use vprintf().
- Fixed vfs.nfs.acdebug sysctl's description.
- Fixed panic when compiled with NFS_ACDEBUG.

MFC after:	3 days
2011-04-13 12:46:25 +00:00
Konstantin Belousov
57bfe0a9f8 Do not fork nfsiod directly from the vop methods. This causes LORs between
vnode lock and several locks needed during fork, like fd lock.

Instead, schedule the task to be executed in the taskqueue context. We
still waiting for the fork to finish, but the context of the thread
executing the task does not make real LORs with our vnode lock.

Submitted by:	pluknet at gmail com
Reviewed by:	jhb
Tested by:	pho
MFC after:	3 weeks
2010-09-12 19:06:08 +00:00
John Baldwin
3c497facfb Retire the NFS access cache timestamp structure. It was used in VOP_OPEN()
to avoid sending multiple ACCESS/GETATTR RPCs during a single open()
between VOP_LOOKUP() and VOP_OPEN().  Now we always send the RPC in
VOP_LOOKUP() and not VOP_OPEN() in the cases that multiple RPCs could be
sent.

MFC after:	2 weeks
2010-07-15 19:40:48 +00:00
Konstantin Belousov
b38f7723eb In NFS clients, instead of inconsistently using #ifdef
DIAGNOSTIC and #ifndef DIAGNOSTIC for debug assertions, prefer
KASSERT(). Also change one #ifdef DIAGNOSTIC in the new nfs server.

Submitted by:	Mikolaj Golub <to.my.trociny gmail com>
MFC after:	2 weeks
2010-06-13 05:24:27 +00:00
Rick Macklem
651ff543f8 Fix a race that can occur when nfs nfsiod threads are being created.
Without this patch it was possible for a different thread that calls
nfs_asyncio() to snitch a newly created nfsiod thread that was
intended for another caller of nfs_asyncio(), because the nfs_iod_mtx
mutex was unlocked while the new nfsiod thread was created. This patch
labels the newly created nfsiod, so that it is not taken by another
caller of nfs_asyncio(). This is believed to fix the problem reported
on the freebsd-stable email list under the subject:
FreeBSD NFS client/Linux NFS server issue.

Tested by:	to DOT my DOT trociny AT gmail DOT com
Reviewed by:	jhb
MFC after:	2 weeks
2010-01-27 15:22:20 +00:00
Konstantin Belousov
48bd6d4a49 In nfs_upgrade_vnlock(), assert that the vnode is locked. It is for all
pathes, as far as I see and testing seems to confirm it. Comparision of
old_lock with LK_SHARED make sense only if vnode is locked by current
thread.

When downgrading, pass LK_RETRY to the vn_lock(), since otherwise
vn_lock() unlocks the doomed vnode, causing extra unlock.

Reported and tested by:	pho
Approved by:	re (rwatson)
MFC after:	3 weeks
2009-08-14 10:59:17 +00:00
Doug Rabson
b49a2b39fd Remove the old kernel RPC implementation and the NFS_LEGACYRPC option.
Approved by: re
2009-06-30 19:03:27 +00:00
Robert Watson
86ce6a83d1 Remove the unmaintained University of Michigan NFSv4 client from 8.x
prior to 8.0-RELEASE.  Rick Macklem's new and more feature-rich NFSv234
client and server are replacing it.

Discussed with:	rmacklem
2009-05-22 12:35:12 +00:00
John Baldwin
3429118095 When a stale file handle is encountered, purge all cached information about
an NFS node including the access and attribute caches.  Previously the NFS
client only purged any name cache entries associated with the file.

PR:		kern/123755
Submitted by:	Jaakko Heinonen  jh of saunalahti fi
Reported by:	Timo Sirainen  tss of iki fi
Reviewed by:	rwatson, rmacklem
MFC after:	1 month
2009-04-06 21:11:08 +00:00
Robert Watson
346ef8cd59 Fix two bugs in DTrace tracing of accesscache and attrcache load events:
- Trace non-error loads into the access cache once, not zero times or
  twice.
- Sometimes attr cache loads fail due to a race, in which case they are
  aborted leading to an invalidation; in this case, trace only the flush,
  not a load.

MFC after:	1 month
Sponsored by:	Google, Inc.
2009-03-24 23:16:48 +00:00
Robert Watson
10263f0832 Add DTrace probes to the NFS access and attribute caches. Access cache
events are:

  nfsclient:accesscache:flush:done
  nfsclient:accesscache:get:hit
  nfsclient:accesscache:get:miss
  nfsclient:accesscache:load:done

They pass the vnode, uid, and requested or loaded access mode (if any);
the load event may also report a load error if the RPC fails.

The attribute cache events are:

  nfsclient:attrcache:flush:done
  nfsclient:attrcache:get:hit
  nfsclient:attrcache:get:miss
  nfsclient:attrcache:load:done

They pass the vnode, optionally the vattr if one is present (hit or load),
and in the case of a load event, also a possible RPC error.

MFC after:	1 month
Sponsored by:	Google, Inc.
2009-03-24 17:14:34 +00:00
Doug Rabson
a9148abd9d Implement support for RPCSEC_GSS authentication to both the NFS client
and server. This replaces the RPC implementation of the NFS client and
server with the newer RPC implementation originally developed
(actually ported from the userland sunrpc code) to support the NFS
Lock Manager.  I have tested this code extensively and I believe it is
stable and that performance is at least equal to the legacy RPC
implementation.

The NFS code currently contains support for both the new RPC
implementation and the older legacy implementation inherited from the
original NFS codebase. The default is to use the new implementation -
add the NFS_LEGACYRPC option to fall back to the old code. When I
merge this support back to RELENG_7, I will probably change this so
that users have to 'opt in' to get the new code.

To use RPCSEC_GSS on either client or server, you must build a kernel
which includes the KGSSAPI option and the crypto device. On the
userland side, you must build at least a new libc, mountd, mount_nfs
and gssd. You must install new versions of /etc/rc.d/gssd and
/etc/rc.d/nfsd and add 'gssd_enable=YES' to /etc/rc.conf.

As long as gssd is running, you should be able to mount an NFS
filesystem from a server that requires RPCSEC_GSS authentication. The
mount itself can happen without any kerberos credentials but all
access to the filesystem will be denied unless the accessing user has
a valid ticket file in the standard place (/tmp/krb5cc_<uid>). There
is currently no support for situations where the ticket file is in a
different place, such as when the user logged in via SSH and has
delegated credentials from that login. This restriction is also
present in Solaris and Linux. In theory, we could improve this in
future, possibly using Brooks Davis' implementation of variant
symlinks.

Supporting RPCSEC_GSS on a server is nearly as simple. You must create
service creds for the server in the form 'nfs/<fqdn>@<REALM>' and
install them in /etc/krb5.keytab. The standard heimdal utility ktutil
makes this fairly easy. After the service creds have been created, you
can add a '-sec=krb5' option to /etc/exports and restart both mountd
and nfsd.

The only other difference an administrator should notice is that nfsd
doesn't fork to create service threads any more. In normal operation,
there will be two nfsd processes, one in userland waiting for TCP
connections and one in the kernel handling requests. The latter
process will create as many kthreads as required - these should be
visible via 'top -H'. The code has some support for varying the number
of service threads according to load but initially at least, nfsd uses
a fixed number of threads according to the value supplied to its '-n'
option.

Sponsored by:	Isilon Systems
MFC after:	1 month
2008-11-03 10:38:00 +00:00
Tom Rhodes
8b4acb0cc0 Document a few sysctls in the NFS client and server code.
Minor style(9) where applicable.

Approved by:	alfred (slightly older version)
2008-11-02 17:00:23 +00:00
Dag-Erling Smørgrav
1ede983cc9 Retire the MALLOC and FREE macros. They are an abomination unto style(9).
MFC after:	3 months
2008-10-23 15:53:51 +00:00
Ruslan Ermilov
ea26d58729 Replaced the misleading uses of a historical artefact M_TRYWAIT with M_WAIT.
Removed dead code that assumed that M_TRYWAIT can return NULL; it's not true
since the advent of MBUMA.

Reviewed by:	arch

There are ongoing disputes as to whether we want to switch to directly using
UMA flags M_WAITOK/M_NOWAIT for mbuf(9) allocation.
2008-03-25 09:39:02 +00:00
Jeff Roberson
698b1a6643 - Complete part of the unfinished bufobj work by consistently using
BO_LOCK/UNLOCK/MTX when manipulating the bufobj.
 - Create a new lock in the bufobj to lock bufobj fields independently.
   This leaves the vnode interlock as an 'identity' lock while the bufobj
   is an io lock.  The bufobj lock is ordered before the vnode interlock
   and also before the mnt ilock.
 - Exploit this new lock order to simplify softdep_check_suspend().
 - A few sync related functions are marked with a new XXX to note that
   we may not properly interlock against a non-zero bv_cnt when
   attempting to sync all vnodes on a mountlist.  I do not believe this
   race is important.  If I'm wrong this will make these locations easier
   to find.

Reviewed by:	kib (earlier diff)
Tested by:	kris, pho (earlier diff)
2008-03-22 09:15:16 +00:00
Attilio Rao
81c794f998 Axe the 'thread' argument from VOP_ISLOCKED() and lockstatus() as it is
always curthread.

As KPI gets broken by this patch, manpages and __FreeBSD_version will be
updated by further commits.

Tested by:	Andrea Barberio <insomniac at slackware dot it>
2008-02-25 18:45:57 +00:00
John Baldwin
3156ea2d33 Consolidate the code to generate a new XID for a NFS request into a
nfs_xid_gen() function instead of duplicating the logic in both
nfsm_rpchead() and the NFS3ERR_JUKEBOX handling in nfs_request().

MFC after:	1 week
Submitted by:	mohans (a long while ago)
2008-02-13 00:04:58 +00:00
Attilio Rao
a3c14ce5d9 namei() can call underlying nfs_readlink() passing a struct uio pointer
owned by a NULL owner. This will lead consequent VOP_ISLOCKED() present
into nfs_upgrade_vnlock() to panic as it only acquire curthread now.
Fix nfs_upgrade_vnlock() and nfs_downgrade_vnlock() in order to not use
more the struct thread pointer passed as argument (as it is really nomore
required there as vn_lock() and VOP_UNLOCK doesn't get the lock more).
Using curthread, in place, doesn't get ambiguity as LK_EXCLOTHER should
be handled as a "not locked" request by both functions.

Reported by: kris
Tested by: kris
Reviewed by: ups
2008-02-09 20:13:19 +00:00
Attilio Rao
d638e093d6 - Introduce the function lockmgr_recursed() which returns true if the
lockmgr lkp, when held in exclusive mode, is recursed
- Introduce the function BUF_RECURSED() which does the same for bufobj
  locks based on the top of lockmgr_recursed()
- Introduce the function BUF_ISLOCKED() which works like the counterpart
  VOP_ISLOCKED(9), showing the state of lockmgr linked with the bufobj

BUF_RECURSED() and BUF_ISLOCKED() entirely replace the usage of bogus
BUF_REFCNT() in a more explicative and SMP-compliant way.
This allows us to axe out BUF_REFCNT() and leaving the function
lockcount() totally unused in our stock kernel. Further commits will
axe lockcount() as well as part of lockmgr() cleanup.

KPI results, obviously, broken so further commits will update manpages
and freebsd version.

Tested by: kris (on UFS and NFS)
2008-01-19 17:36:23 +00:00
Attilio Rao
22db15c06f VOP_LOCK1() (and so VOP_LOCK()) and VOP_UNLOCK() are only used in
conjuction with 'thread' argument passing which is always curthread.
Remove the unuseful extra-argument and pass explicitly curthread to lower
layer functions, when necessary.

KPI results broken by this change, which should affect several ports, so
version bumping and manpage update will be further committed.

Tested by: kris, pho, Diego Sardina <siarodx at gmail dot com>
2008-01-13 14:44:15 +00:00
Attilio Rao
cb05b60a89 vn_lock() is currently only used with the 'curthread' passed as argument.
Remove this argument and pass curthread directly to underlying
VOP_LOCK1() VFS method. This modify makes the code cleaner and in
particular remove an annoying dependence helping next lockmgr() cleanup.
KPI results, obviously, changed.

Manpage and FreeBSD_version will be updated through further commits.

As a side note, would be valuable to say that next commits will address
a similar cleanup about VFS methods, in particular vop_lock1 and
vop_unlock.

Tested by:	Diego Sardina <siarodx at gmail dot com>,
		Andrea Di Pasquale <whyx dot it at gmail dot com>
2008-01-10 01:10:58 +00:00
Mohan Srinivasan
faf529dce5 NFS MP scaling changes.
- Eliminate the hideous nfs_sndlock that serialized NFS/TCP request senders
  thru the sndlock.
- Institute a new nfs_connectlock that serializes NFS/TCP reconnects. Add
  logic to wait for pending request senders to finish sending before
  reconnecting. Dial down the sb_timeo for NFS/TCP sockets to 1 sec.
- Break out the nfs xid manipulation under a new nfs xid lock, rather than
  over loading the nfs request lock for this purpose.
- Fix some of the locking in nfs_request.
Many thanks to Kris Kennaway for his help with this and for initiating the
MP scaling analysis and work. Kris also tested this patch thorougly.
Approved by: re@ (Ken Smith)
2007-10-12 19:12:21 +00:00
John Baldwin
f4b65ca5d0 Fix for a race where out of order loading of NFS attrs into the
nfsnode could lead to attrs being stale. One example (that we
ran into) was a READDIR+, WRITE. The responses came back in
order, but the attrs from the WRITE were loaded before the
attrs from the READDIR+, leading to the wrong size from being
read on the next stat() call.

MFC after:	1 week
Submitted by:	mohans
Approved by:	re (kensmith)
2007-07-03 18:31:47 +00:00
Mohan Srinivasan
f9bb753844 Over NFS, an open() call could result in multiple over-the-wire
GETATTRs being generated - one from lookup()/namei() and the other
from nfs_open() (for cto consistency). This change eliminates the
GETATTR in nfs_open() if an otw GETATTR was done from the namei()
path. Instead of extending the vop interface, we timestamp each attr
load, and use this to detect whether a GETATTR was done from namei()
for this syscall. Introduces a thread-local variable that counts the
syscalls made by the thread and uses <pid, tid, thread syscalls> as
the attrload timestamp. Thanks to jhb@ and peter@ for a discussion on
thread state that could be used as the timestamp with minimal overhead.
2007-03-09 04:02:38 +00:00
Mohan Srinivasan
7d7d9e2242 Fixes up the handling of shared vnode lock lookups in the NFS client,
adds a FS type specific flag indicating that the FS supports shared
vnode lock lookups, adds some logic in vfs_lookup.c to test this flag
and set lock flags appropriately.

- amd on 6.x is a non-starter (without this change). Using amd under
  heavy load results in a deadlock (with cascading vnode locks all the
  way to the root) very quickly.
- This change should also fix the more general problem of cascading
  vnode deadlocks when an NFS server goes down.

Ideally, we wouldn't need these changes, as enabling shared vnode lock
lookups globally would work. Unfortunately, UFS, for example isn't
ready for shared vnode lock lookups, crashing pretty quickly.

This change is the result of discussions with Stephan Uphoff (ups@).

Reviewed by:	ups@
2006-09-13 18:39:09 +00:00
Mohan Srinivasan
f1cdf89911 Changes to make the NFS client MP safe.
Thanks to Kris Kennaway for testing and sending lots of bugs my way.
2006-05-19 00:04:24 +00:00
Jim Rees
cb156cc603 fix a problem with XID re-use when a server returns NFSERR_JUKEBOX.
Submitted by:	cel@citi.umich.edu
Fixed by:	rick@snowhite.cis.uoguelph.ca
Approved by:	alfred
MFC after:	3 weeks
2005-11-21 18:39:18 +00:00
Paul Saab
4321eae6b7 Make nfs_timer() MPSAFE. With this change, the bottom half of the NFS
client (the interface with the protocol stack and callouts) is
Giant-free.

Submitted by:	Mohan Srinivasan.
2005-07-19 21:27:25 +00:00
Jeff Roberson
c0f681c21d - The VI_DOOMED flag now signals the end of a vnode's relationship with
the filesystem.  Check that rather than VI_XLOCK.

Sponsored by:	Isilon Systems, Inc.
2005-03-13 12:14:56 +00:00
Warner Losh
c398230b64 /* -> /*- for license, minor formatting changes 2005-01-07 01:45:51 +00:00
Paul Saab
35ec46b7f2 Rewrite of the NFS client's reply handling. We now have NFS socket
upcalls which do RPC header parsing and match up the reply with the
request. NFS calls now sleep on the nfsreq structure. This enables
us to eliminate the NFS recvlock.

Submitted by:	Mohan Srinivasan mohans at yahoo-inc dot com
2004-12-06 21:11:15 +00:00
Paul Saab
ddc6c40075 2 fixes that improve on the consistency of the NFS client cache.
- Change the cached mtime to a 'struct timespec' from a
  time_t. Improving the precision of the cached mtime tightens up
  NFS' "close-to-open" consistency considerably.
- Always force an over-the-wire consistency check from nfs_open()
  (unless the file is marked modified). This further improves
  NFS' "close-to-open" consistency.

Submitted by:	Mohan Srinivasan mohans at yahoo-inc dot com
2004-12-06 19:18:00 +00:00
Paul Saab
b8d0fc9581 Add non-blocking versions of nfsm_dissect() and friends, for use from
socket callbacks or similar callers, from both the NFS client and the
server.
Instituted nfsm_dissect_nonblock(), nfsm_dissect_xx_nonblock(). And
nfsm_disct() now takes an extra M_TRYWAIT/M_DONTWAIT argument.

Submitted by:	Mohan Srinivasan mohans at yahoo-inc dot com
2004-12-06 17:33:52 +00:00
Poul-Henning Kamp
8b431c9576 For reasons unknown, the nfs locking code used a fifo to send requests to
userland and a dedicated system call to get replies.

The vnode-bypass of fifos broke this into a panic.

Ditch all the magic and create a device /dev/nfslock instead, and
use that for both directions apart from the shorter path, this is
also faster because the device driver runs Giant free using the
vnode bypass.

Noticed by:	marcel
2004-12-06 08:31:32 +00:00
Poul-Henning Kamp
aec0fb7b40 Back when VOP_* was introduced, we did not have new-style struct
initializations but we did have lofty goals and big ideals.

Adjust to more contemporary circumstances and gain type checking.

	Replace the entire vop_t frobbing thing with properly typed
	structures.  The only casualty is that we can not add a new
	VOP_ method with a loadable module.  History has not given
	us reason to belive this would ever be feasible in the the
	first place.

	Eliminate in toto VOCALL(), vop_t, VNODEOP_SET() etc.

	Give coda correct prototypes and function definitions for
	all vop_()s.

	Generate a bit more data from the vnode_if.src file:  a
	struct vop_vector and protype typedefs for all vop methods.

	Add a new vop_bypass() and make vop_default be a pointer
	to another struct vop_vector.

	Remove a lot of vfs_init since vop_vector is ready to use
	from the compiler.

	Cast various vop_mumble() to void * with uppercase name,
	for instance VOP_PANIC, VOP_NULL etc.

	Implement VCALL() by making vdesc_offset the offsetof() the
	relevant function pointer in vop_vector.  This is disgusting
	but since the code is generated by a script comparatively
	safe.  The alternative for nullfs etc. would be much worse.

	Fix up all vnode method vectors to remove casts so they
	become typesafe.  (The bulk of this is generated by scripts)
2004-12-01 23:16:38 +00:00
Poul-Henning Kamp
494eb176e7 Add b_bufobj to struct buf which eventually will eliminate the need for b_vp.
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.
2004-10-22 08:47:20 +00:00
Poul-Henning Kamp
a76d8f4ec9 Move the VI_BWAIT flag into no bo_flag element of bufobj and call it BO_WWAIT
Add bufobj_wref(), bufobj_wdrop() and bufobj_wwait() to handle the write
count on a bufobj.  Bufobj_wdrop() replaces vwakeup().

Use these functions all relevant places except in ffs_softdep.c where
the use if interlocked_sleep() makes this impossible.

Rename b_vnbufs to b_bobufs now that we touch all the relevant files anyway.
2004-10-21 15:53:54 +00:00
Poul-Henning Kamp
c0f46dd1e4 Remove support for using NFS device nodes. 2004-09-28 08:50:01 +00:00
Poul-Henning Kamp
e3c5a7a4dd When we traverse the vnodes on a mountpoint we need to look out for
our cached 'next vnode' being removed from this mountpoint.  If we
find that it was recycled, we restart our traversal from the start
of the list.

Code to do that is in all local disk filesystems (and a few other
places) and looks roughly like this:

		MNT_ILOCK(mp);
	loop:
		for (vp = TAILQ_FIRST(&mp...);
		    (vp = nvp) != NULL;
		    nvp = TAILQ_NEXT(vp,...)) {
			if (vp->v_mount != mp)
				goto loop;
			MNT_IUNLOCK(mp);
			...
			MNT_ILOCK(mp);
		}
		MNT_IUNLOCK(mp);

The code which takes vnodes off a mountpoint looks like this:

	MNT_ILOCK(vp->v_mount);
	...
	TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
	...
	MNT_IUNLOCK(vp->v_mount);
	...
	vp->v_mount = something;

(Take a moment and try to spot the locking error before you read on.)

On a SMP system, one CPU could have removed nvp from our mountlist
but not yet gotten to assign a new value to vp->v_mount while another
CPU simultaneously get to the top of the traversal loop where it
finds that (vp->v_mount != mp) is not true despite the fact that
the vnode has indeed been removed from our mountpoint.

Fix:

Introduce the macro MNT_VNODE_FOREACH() to traverse the list of
vnodes on a mountpoint while taking into account that vnodes may
be removed from the list as we go.  This saves approx 65 lines of
duplicated code.

Split the insmntque() which potentially moves a vnode from one mount
point to another into delmntque() and insmntque() which does just
what the names say.

Fix delmntque() to set vp->v_mount to NULL while holding the
mountpoint lock.
2004-07-04 08:52:35 +00:00
Poul-Henning Kamp
f3732fd15b Second half of the dev_t cleanup.
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.
2004-06-17 17:16:53 +00:00
Peter Edwards
7c8ca9400e Let the NFS client notice a file's size changing as a modification.
This avoids presenting invalid data to the client's applications
when the file is modified, and then extended within the window of
the resolution of the modifcation timestamp.

Reviewed By:	iedowse
PR:		kern/64091
2004-04-14 23:23:55 +00:00
Marcel Moolenaar
5fa064a8d8 Unbreak build: s/TAILQ_ISEMPTY/TAILQ_EMPTY/g 2004-04-11 17:15:36 +00:00