Remove the vfs.reassignbufcalls counter and sysctl.

As the 20-year old comment above it suggests, the counter is of dubious
value. Moreover, the (global) counter was not updated precisely and
hurts

Remove the vfs.reassignbufcalls counter and sysctl.

As the 20-year old comment above it suggests, the counter is of dubious
value. Moreover, the (global) counter was not updated precisely and
hurts scalability.

Reviewed by: cem, kib, mjg
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D25965

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vfs: remove the obsolete privused argument from vaccess

This brings argument count down to 6, which is passable without the
stack on amd64.

vfs: support lockless dotdot lookup

Tested by: pho

cache: add cache_purge_vgone

cache_purge locklessly checks whether the vnode at hand has any namecache
entries. This can race with a concurrent purge which managed to remove
the last entry, but may

cache: add cache_purge_vgone

cache_purge locklessly checks whether the vnode at hand has any namecache
entries. This can race with a concurrent purge which managed to remove
the last entry, but may not be done touching the vnode.

Make sure we observe the relevant vnode lock as not taken before proceeding
with vgone.

Paired with the fact that doomed vnodes cannnot receive entries this restores
the invariant that there are no namecache-related writing users past cache_purge
in vgone.

Reported by: pho

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vfs: move namecache initialisation into cache_vnode_init

vfs: inline vops if there are no pre/post associated calls

This removes a level of indirection from frequently used methods, most notably
VOP_LOCK1 and VOP_UNLOCK1.

Tested by: pho

vfs: add the infrastructure for lockless lookup

Reviewed by: kib
Tested by: pho (in a patchset)
Differential Revision: https://reviews.freebsd.org/D25577

vfs: introduce vnode sequence counters

Modified on each permission change and link/unlink.

Reviewed by: kib
Tested by: pho (in a patchset)
Differential Revision: https://reviews.freebsd.org/D25573

Add unlocked/SMR fast path to getblk()

Convert the bufobj tries to an SMR zone/PCTRIE and add a gbincore_unlocked()
API wrapping this functionality. Use it for a fast path in getblkx(),
falling bac

Add unlocked/SMR fast path to getblk()

Convert the bufobj tries to an SMR zone/PCTRIE and add a gbincore_unlocked()
API wrapping this functionality. Use it for a fast path in getblkx(),
falling back to locked lookup if we raced a thread changing the buf's
identity.

Reported by: Attilio
Reviewed by: kib, markj
Testing: pho (in progress)
Sponsored by: Isilon
Differential Revision: https://reviews.freebsd.org/D25782

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vfs: fix trivial whitespace issues which don't interefere with blame

.. even without the -w switch

vfs: expand on vhold_smr comment

vfs: protect vnodes with smr

vget_prep_smr and vhold_smr can be used to ref a vnode while within vfs_smr
section, allowing consumers to get away without locking.

See vhold_smr and vdropl for commen

vfs: protect vnodes with smr

vget_prep_smr and vhold_smr can be used to ref a vnode while within vfs_smr
section, allowing consumers to get away without locking.

See vhold_smr and vdropl for comments explaining caveats.

Reviewed by: kib
Testec by: pho
Differential Revision: https://reviews.freebsd.org/D23913

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Deduplicate fsid comparisons

Comparing fsid_t objects requires internal knowledge of the fsid structure
and yet this is duplicated across a number of places in the code.

Simplify by creating a fsid

Deduplicate fsid comparisons

Comparing fsid_t objects requires internal knowledge of the fsid structure
and yet this is duplicated across a number of places in the code.

Simplify by creating a fsidcmp function (macro).

Reviewed by: mjg, rmacklem
Approved by: mav (mentor)
MFC after: 1 week
Sponsored by: iXsystems, Inc.
Differential Revision: https://reviews.freebsd.org/D24749

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Add a new "mntfs" pseudo file system which provides private device vnodes for
file systems to safely access their disk devices, and adapt FFS to use it.
Also add a new BO_NOBUFS flag to allow enforci

Add a new "mntfs" pseudo file system which provides private device vnodes for
file systems to safely access their disk devices, and adapt FFS to use it.
Also add a new BO_NOBUFS flag to allow enforcing that file systems using
mntfs vnodes do not accidentally use the original devfs vnode to create buffers.

Reviewed by: kib, mckusick
Approved by: imp (mentor)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D23787

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vfs: quiet -Wwrite-strings

Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D23797

Eliminate some unnecessary uses of UMA_ZONE_VM. Only zones involved in
virtual address or physical page allocation need to be marked with this
flag.

Reviewed by: markj
Tested by: pho
Differential R

Eliminate some unnecessary uses of UMA_ZONE_VM. Only zones involved in
virtual address or physical page allocation need to be marked with this
flag.

Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D23712

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vfs: fix vlrureclaim ->v_object access

The routine was checking for ->v_type == VBAD. Since vgone drops the interlock
early sets this type at the end of the process of dooming a vnode, this opens
a

vfs: fix vlrureclaim ->v_object access

The routine was checking for ->v_type == VBAD. Since vgone drops the interlock
early sets this type at the end of the process of dooming a vnode, this opens
a time window where it can clear the pointer while the inerlock-holders is
accessing it.

Another note is that the code was:
(vp->v_object != NULL &&
vp->v_object->resident_page_count > trigger)

With the compiler being fully allowed to emit another read to get the pointer,
and in fact it did on the kernel used by pho.

Use atomic_load_ptr and remember the result.

Note that this depends on type-safety of vm_object.

Reported by: pho

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vfs: check early for VCHR in vput_final to short-circuit in the common case

Otherwise the compiler inlines v_decr_devcount which keps getting jumped over
in the common case of not dealing with a dev

vfs: check early for VCHR in vput_final to short-circuit in the common case

Otherwise the compiler inlines v_decr_devcount which keps getting jumped over
in the common case of not dealing with a device.

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vfs: remove no longer needed atomic_load_ptr casts

vfs: refactor vputx and add more comment

Reviewed by: jeff (previous version)
Tested by: pho (previous version)
Differential Revision: https://reviews.freebsd.org/D23530

vfs: switch to smp_rendezvous_cpus_retry for vfs_op_thread_enter/exit

In particular on amd64 this eliminates an atomic op in the common case,
trading it for IPIs in the uncommon case of catching CPU

vfs: switch to smp_rendezvous_cpus_retry for vfs_op_thread_enter/exit

In particular on amd64 this eliminates an atomic op in the common case,
trading it for IPIs in the uncommon case of catching CPUs executing the
code while the filesystem is getting suspended or unmounted.

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vfs: fix vhold race in mnt_vnode_next_lazy_relock

vdrop can set the hold count to 0 and wait for the ->mnt_listmtx held by
mnt_vnode_next_lazy_relock caller. The routine incorrectly asserted the
cou

vfs: fix vhold race in mnt_vnode_next_lazy_relock

vdrop can set the hold count to 0 and wait for the ->mnt_listmtx held by
mnt_vnode_next_lazy_relock caller. The routine incorrectly asserted the
count has to be > 0.

Reported by: pho
Tested by: pho

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vfs: fix device count leak on vrele racing with vgone

The race is:

CPU1 CPU2
devfs_reclaim_vchr
make v_usecount 0

vfs: fix device count leak on vrele racing with vgone

The race is:

CPU1 CPU2
devfs_reclaim_vchr
make v_usecount 0
VI_LOCK
sees v_usecount == 0, no updates
vp->v_rdev = NULL;
...
VI_UNLOCK
VI_LOCK
v_decr_devcount
sees v_rdev == NULL, no updates

In this scenario si_devcount decrement is not performed.

Note this can only happen if the vnode lock is not held.

Reviewed by: kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D23529

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vfs: fix lock recursion in vrele

vrele is supposed to be called with an unlocked vnode, but this was never
asserted for if v_usecount was > 0. For such counts the lock is never touched
by the routin

vfs: fix lock recursion in vrele

vrele is supposed to be called with an unlocked vnode, but this was never
asserted for if v_usecount was > 0. For such counts the lock is never touched
by the routine. As a result the kernel has several consumers which expect
vunref semantics and get away with calling vrele since they happen to never do
it when this is the last reference (and for some of them this may happen to be
a guarantee).

Work around the problem by changing vrele semantics to tolerate being called
with a lock. This eliminates a possible bug where the lock is already held and
vputx takes it anyway.

Reviewed by: kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D23528

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vfs: tidy up vget_finish and vn_lock

- remove assertion which duplicates vn_lock
- use VNPASS instead of retyping the failure
- report what flags were passed if panicking on them