Commit Graph

26 Commits

Author SHA1 Message Date
Konstantin Belousov
0fc6daa72d - Fix nullfs vnode reference leak in nullfs_reclaim_lowervp(). The
null_hashget() obtains the reference on the nullfs vnode, which must
  be dropped.

- Fix a wart which existed from the introduction of the nullfs
  caching, do not unlock lower vnode in the nullfs_reclaim_lowervp().
  It should be innocent, but now it is also formally safe.  Inform the
  nullfs_reclaim() about this using the NULLV_NOUNLOCK flag set on
  nullfs inode.

- Add a callback to the upper filesystems for the lower vnode
  unlinking. When inactivating a nullfs vnode, check if the lower
  vnode was unlinked, indicated by nullfs flag NULLV_DROP or VV_NOSYNC
  on the lower vnode, and reclaim upper vnode if so.  This allows
  nullfs to purge cached vnodes for the unlinked lower vnode, avoiding
  excessive caching.

Reported by:	G??ran L??wkrantz <goran.lowkrantz@ismobile.com>
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2013-05-11 11:17:44 +00:00
Konstantin Belousov
9cf4c952ca Add the "nocache" nullfs mount option, which disables the caching of
the free nullfs vnodes, switching nullfs behaviour to pre-r240285.
The option is mostly intended as the last-resort when higher pressure
on the vnode cache due to doubling of the vnode counts is not
desirable.

Note that disabling the cache costs more than 2x wall time in the
metadata-hungry scenarious.  The default is "cache".

Tested and benchmarked by:	pho (previous version)
MFC after:	2 weeks
2013-01-03 19:17:57 +00:00
Konstantin Belousov
d9e9650a36 Allow shared lookups for nullfs mounts, if lower filesystem supports
it.  There are two problems which shall be addressed for shared
lookups use to have measurable effect on nullfs scalability:

1. When vfs_lookup() calls VOP_LOOKUP() for nullfs, which passes lookup
operation to lower fs, resulting vnode is often only shared-locked. Then
null_nodeget() cannot instantiate covering vnode for lower vnode, since
insmntque1() and null_hashins() require exclusive lock on the lower.

Change the assert that lower vnode is exclusively locked to only
require any lock.  If null hash failed to find pre-existing nullfs
vnode for lower vnode and the vnode is shared-locked, the lower vnode
lock is upgraded.

2. Nullfs reclaims its vnodes on deactivation. This is due to nullfs
inability to detect reclamation of the lower vnode.  Reclamation of a
nullfs vnode at deactivation time prevents a reference to the lower
vnode to become stale.

Change nullfs VOP_INACTIVE to not reclaim the vnode, instead use the
VFS_RECLAIM_LOWERVP to get notification and reclaim upper vnode
together with the reclamation of the lower vnode.

Note that nullfs reclamation procedure calls vput() on the lowervp
vnode, temporary unlocking the vnode being reclaimed. This seems to be
fine for MPSAFE filesystems, but not-MPSAFE code often put partially
initialized vnode on some globally visible list, and later can decide
that half-constructed vnode is not needed.  If nullfs mount is created
above such filesystem, then other threads might catch such not
properly initialized vnode. Instead of trying to overcome this case,
e.g. by recursing the lower vnode lock in null_reclaim_lowervp(), I
decided to rely on nearby removal of the support for non-MPSAFE
filesystems.

In collaboration with:	pho
MFC after:	3 weeks
2012-09-09 19:20:23 +00:00
Jeff Roberson
bc855512c8 - Assume that all lower filesystems now support proper locking. Assert
that they set v->v_vnlock.  This is true for all filesystems in the
   tree.
 - Remove all uses of LK_THISLAYER.  If the lower layer is locked, the
   null layer is locked.  We only use vget() to get a reference now.
   null essentially does no locking.  This fixes LOOKUP_SHARED with
   nullfs.
 - Remove the special LK_DRAIN considerations, I do not believe this is
   needed now as LK_DRAIN doesn't destroy the lower vnode's lock, and
   it's hardly used anymore.
 - Add one well commented hack to prevent the lowervp from going away
   while we're in it's VOP_LOCK routine.  This can only happen if we're
   forcibly unmounted while some callers are waiting in the lock.  In
   this case the lowervp could be recycled after we drop our last ref
   in null_reclaim().  Prevent this with a vhold().
2005-03-15 13:49:33 +00:00
Warner Losh
d167cf6f3a /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 18:10:42 +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
Warner Losh
f36cfd49ad Remove advertising clause from University of California Regent's
license, per letter dated July 22, 1999 and email from Peter Wemm,
Alan Cox and Robert Watson.

Approved by: core, peter, alc, rwatson
2004-04-07 20:46:16 +00:00
Tim J. Robbins
549398753a MFp4: Fix two bugs causing possible deadlocks or panics, and one nit:
- Emulate lock draining (LK_DRAIN) in null_lock() to avoid deadlocks
  when the vnode is being recycled.
- Don't allow null_nodeget() to return a nullfs vnode from the wrong
  mount when multiple nullfs's are mounted. It's unclear why these checks
  were removed in null_subr.c 1.35, but they are definitely necessary.
  Without the checks, trying to unmount a nullfs mount will erroneously
  return EBUSY, and forcibly unmounting with -f will cause a panic.
- Bump LOG2_SIZEVNODE up to 8, since vnodes are >256 bytes now. The old
  value (7) didn't cause any problems, but made the hash algorithm
  suboptimal.

These changes fix nullfs enough that a parallel buildworld succeeds.

Submitted by:	tegge (partially; LK_DRAIN)
Tested by:	kris
2003-06-17 08:52:45 +00:00
Semen Ustimenko
1cfdefbb9f Fix a race during null node creation between relookuping the hash and
adding vnode to hash. The fix is to use atomic hash-lookup-and-add-if-
not-found operation. The odd thing is that this race can't happen
actually because the lowervp vnode is locked exclusively now during the
whole process of null node creation. This must be thought as a step
toward shared lookups.

Also remove vp->v_mount checks when looking for a match in the hash,
as this is the vestige.

Also add comments and cosmetic changes.
2002-06-13 21:49:09 +00:00
Semen Ustimenko
08720e34b0 Fix the "error" path (when dropping not fully initialized vnode).
Also move hash operations out of null_vnops.c and explicitly initialize
v_lock in null_node_alloc (to set wmesg).

Reviewed by:	bp
MFC after:	2 weeks
2002-06-13 18:25:06 +00:00
Maxime Henrion
9fcc512cd6 Convert nullfs to nmount. 2002-05-23 23:07:27 +00:00
Boris Popov
8da8066061 Various cleanups towards make nullfs functional (it is still broken
at this point):

Replace all '#ifdef DEBUG' with '#ifdef NULLFS_DEBUG' and add NULLFSDEBUG
macro.

Protect nullfs hash table with lockmgr.

Use proper order of operations when freeing mnt_data.

Return correct fsid in the null_getattr().

Add null_open() function to catch MNT_NODEV (obtained from NetBSD).

Add null_rename() to catch cross-fs rename operations (submitted by
Ustimenko Semen <semen@iclub.nsu.ru>)

Remove duplicate $FreeBSD$ tags.
2000-09-05 09:02:07 +00:00
Boris Popov
7da1e3f0b0 Get rid from the __P() macros.
Encouraged by:	peter
2000-09-05 07:54:39 +00:00
Jake Burkholder
e39756439c Back out the previous change to the queue(3) interface.
It was not discussed and should probably not happen.

Requested by:		msmith and others
2000-05-26 02:09:24 +00:00
Jake Burkholder
740a1973a6 Change the way that the queue(3) structures are declared; don't assume that
the type argument to *_HEAD and *_ENTRY is a struct.

Suggested by:	phk
Reviewed by:	phk
Approved by:	mdodd
2000-05-23 20:41:01 +00:00
Peter Wemm
c447342094 Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL"
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.
1999-12-29 05:07:58 +00:00
Bruce Evans
a0f40f54aa Get rid of the NULLFS_DIAGNOSTIC option. This option was as useful as
the other XXXFS_DIAGNOSTIC options (not very) and mostly controlled
tracing of normal operation.  Use `#ifdef DEBUG' for non-diagnostics
and `#ifdef DIAGNOSTIC' for diagnostics.
1999-09-04 12:35:09 +00:00
Peter Wemm
c3aac50f28 $Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00
Bruce Evans
bea0f0be7b Some staticized variables were still declared to be extern. 1997-09-07 05:27:26 +00:00
Peter Wemm
e9f7506f89 Fix some warnings (missing prototypes, wrong "generic" args etc)
umapfs uses one of nullfs's functions...
1997-05-25 04:50:02 +00:00
Peter Wemm
6875d25465 Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.
1997-02-22 09:48:43 +00:00
Mike Pritchard
63f50488b0 Make this compile again after the Lite2 merge.
Also add missing function prototypes.
1997-02-12 14:55:01 +00:00
John Dyson
996c772f58 This is the kernel Lite/2 commit. There are some requisite userland
changes, so don't expect to be able to run the kernel as-is (very well)
without the appropriate Lite/2 userland changes.

The system boots and can mount UFS filesystems.

Untested: ext2fs, msdosfs, NFS
Known problems: Incorrect Berkeley ID strings in some files.
		Mount_std mounts will not work until the getfsent
		library routine is changed.

Reviewed by:	various people
Submitted by:	Jeffery Hsu <hsu@freebsd.org>
1997-02-10 02:22:35 +00:00
Jordan K. Hubbard
1130b656e5 Make the long-awaited change from $Id$ to $FreeBSD$
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore.  This update would have been
insane otherwise.
1997-01-14 07:20:47 +00:00
Bruce Evans
f57e65478d Introduced a type `vop_t' for vnode operation functions and used
it 1138 times (:-() in casts and a few more times in declarations.
This change is null for the i386.

The type has to be `typedef int vop_t(void *)' and not `typedef
int vop_t()' because `gcc -Wstrict-prototypes' warns about the
latter.  Since vnode op functions are called with args of different
(struct pointer) types, neither of these function types is any use
for type checking of the arg, so it would be preferable not to use
the complete function type, especially since using the complete
type requires adding 1138 casts to avoid compiler warnings and
another 40+ casts to reverse the function pointer conversions before
calling the functions.
1995-11-09 08:17:23 +00:00
Rodney W. Grimes
df8bae1de4 BSD 4.4 Lite Kernel Sources 1994-05-24 10:09:53 +00:00