- vcache_get() retrieves a referenced and initialised vnode / fs node pair.
- vcache_remove() removes a vnode / fs node pair from the cache.
On cache miss vcache_get() calls new vfs operation vfs_loadvnode() to
initialise a vnode / fs node pair. This call is guaranteed exclusive,
no other thread will try to load this vnode / fs node pair.
Convert ufs/ext2fs, ufs/ffs and ufs/mfs to use this interface.
Remove now unused ufs/ufs_ihash
Discussed on tech-kern.
Welcome to 6.99.41
caller has to care about list and vnode mutexes, reference count being zero,
intermediate vnode states like VI_CLEAN, VI_XLOCK, VI_MARKER and so on.
Add an interface to iterate over a vnode list:
void vfs_vnode_iterator_init(struct mount *mp, struct vnode_iterator **marker)
void vfs_vnode_iterator_destroy(struct vnode_iterator *marker)
bool vfs_vnode_iterator_next(struct vnode_iterator *marker, struct vnode **vpp)
vfs_vnode_iterator_next() returns either "false / *vpp == NULL" when done
or "true / *vpp != NULL" to return the next referenced vnode from the list.
To make vrecycle() work in this environment change it to
bool vrecycle(struct vnode *vp)
where "vp" is a referenced vnode to be destroyed if this is the last reference.
Discussed on tech-kern.
Welcome to 6.99.34
the vnode operations vector for active vnodes is unsafe because it
is not known whether deadfs or the original file system will be
called.
- Pass down LK_RETRY to the lock operation (hint for deadfs only).
- Change deadfs lock operation to return ENOENT if LK_RETRY is unset.
- Change all other lock operations to check for dead vnode once
the vnode is locked and unlock and return ENOENT in this case.
With these changes in place vnode lock operations will never succeed
after vclean() has marked the vnode as VI_XLOCK and before vclean()
has changed the operations vector.
Adresses PR kern/37706 (Forced unmount of file systems is unsafe)
Discussed on tech-kern.
Welcome to 6.99.33
- No need to always defer layer vnodes, if we get the vnode lock it
is safe to inactivate.
- Always use VOP_LOCK(), it makes no sense to use vn_lock() here.
- No need to drop v_interlock for VOP_LOCK(... LK_NOWAIT).
the vnode lock but before it calls VOP_INACTIVE().
Should fix the race between layer_node_find() trying to vget(, LK_NOWAIT)
a locked vnode when vrelel() marked it as changing and wants its lock.
PR kern/48411 (repeatable SMP crashes in amd64-current)
set while a vnode changes state from active to inactive or from active
or inactive to clean and protects "vclean(); vrelel()" and "vrelel()"
against "vget()".
Presented on tech-kern.
- VC_XLOCK/VC_MASK are not used anymore, remove.
- If we get a reference while cleaning, there is no need to retry as
these reference and this vnode will disappear soon.
- Make sure we run inside a fstrans transaction to prevent deadlocks
against vget().
vrecycle():
- don't even try to recycle a vnode currently cleaning.
- Make these defines and functions private to vfs_vnode.c:
VC_MASK, VC_LOCK, DOCLOSE, VI_IANCTREDO and VI_INACTNOW
vclean() and vrelel()
- Remove the long time unused lwp argument from vrecycle().
- Remove vtryget(), it is responsible for ugly hacks and doesn't
look that effective.
Presented on tech-kern.
Welcome to 6.99.25
To retrieve a spec_node, two new lookup functions (by device or by mount)
are implemented. Both return a referenced vnode, for an opened block device
the opened vnode is returned so further diagnostic checks "vp == ... sd_bdevvp"
will not fire. Otherwise any vnode matching the criteria gets returned.
No objections on tech-kern.
Welcome to 6.99.17
As long as we hold the vnode interlock there is no chance for this vnode
to gain new references.
Fixes false alarms observed by Thor Lancelot Simon and reported on tech-kern.
Ok: David Holland <dholland@netbsd.org>
if the vnode we want to clean is a layered vnode and the caller already
locked its lower vnode.
Change getnewvnode() to always allocate a fresh vnode and add a helper
thread (vdrain) to keep the number of allocated vnodes within desiredvnodes.
Rename getcleanvnode() to cleanvnode() and let it take a vnode from the
lists, clean and free it.
Reviewed by: David Holland <dholland@netbsd.org>
Should fix:
PR #19110 (nullfs mounts over NFS cause lock manager problems)
PR #34102 (ffs panic in NetBSD 3.0_STABLE)
PR #45115 (lock error panic when build.sh*3 and daily script is running)
PR #45355 (Reader/writer lock error: rw_vector_enter: locking against myself)
- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.
- Simplify locking in some pmap(9) modules by removing P->V locking.
- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).
- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.
- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.
Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.
hannken