vfs: fix stale comment about freevnodes management

vfs: don't kick vnlru if it is already running

Further shaves some lock trips.

vfs: drop one vnode list lock trip during vnlru free recycle

vnlru_free_impl would take the lock prior to returning even though most
frequent caller does not need it.

Unsurprisingly vnode_list mtx

vfs: drop one vnode list lock trip during vnlru free recycle

vnlru_free_impl would take the lock prior to returning even though most
frequent caller does not need it.

Unsurprisingly vnode_list mtx is the primary bottleneck when recycling
and avoiding the useless lock trip helps.

Setting maxvnodes to 400000 and running 20 parallel finds each with a
dedicated directory tree of 1 million vnodes in total:
before: 4.50s user 1225.71s system 1979% cpu 1:02.14 total
after: 4.20s user 806.23s system 1973% cpu 41.059 total

That's 34% reduction in total real time.

With this the block *remains* the primary bottleneck when running on
ZFS.

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vfs: retried++ -> retried = true for the boolean

No real changes.

Noted by: rpokala

vfs: try harder to find free vnodes when recycling

The free vnode marker can slide past eligible entries.

Artificially reducing vnode limit to 300k and spawning 104 workers each
creating a million

vfs: try harder to find free vnodes when recycling

The free vnode marker can slide past eligible entries.

Artificially reducing vnode limit to 300k and spawning 104 workers each
creating a million files results in all of them trying to recycle, which
often fails when it should not have to.

Because of the excessive traffic in this scenario, the trylock to
requeue is virtually guaranteed to fail, meaning nothing gets pushed
forward.

Since no vnodes were found, the most unfortunate sleep for 1 second is
induced (see vn_alloc_hard, the "vlruwk" msleep).

Without the fix the machine is mostly idle with almost everyone stuck
off CPU waiting for the sleep to finish. With the fix it is busy
creating files.

Unrelated to the above problem the marker could have landed in a
similarly problematic spot for because of any failure in vtryrecycle.

Originally reported as poudriere builders stalling in a vnode-count
restricted setup.

Fixes: 138a5dafba31 ("vfs: trylock vnode requeue")
Reported by: Mark Millard

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vfs: track how many times vn_alloc blocked on hitting the vnode limit

sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Revert "VFS: Remove VV_READLINK flag" and "fdescfs: improve linrdlnk mount option"

This reverts commits 4a402dfe0bc44770c9eac6e58a501e4805e29413 and
3bffa2262328e4ff1737516f176107f607e7bc76.

The fi

Revert "VFS: Remove VV_READLINK flag" and "fdescfs: improve linrdlnk mount option"

This reverts commits 4a402dfe0bc44770c9eac6e58a501e4805e29413 and
3bffa2262328e4ff1737516f176107f607e7bc76.

The fix will be implemented in somewhat different manner. The semantic
adjustment is incompatible with linuxolator expectations.

Reported and reviewed by: dchagin
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D40969

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vfs: use __enum_uint8 for vtype and vstate

This whacks hackery around only reading v_type once.

Bump __FreeBSD_version to 1400093

VFS: Remove VV_READLINK flag

since its only reason to exist is removed.

Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://revie

VFS: Remove VV_READLINK flag

since its only reason to exist is removed.

Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D40700

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vfs: Rename vfs_emptydir() to vn_dir_check_empty()

No functional change. While here, adapt comments to style(9).

Reviewed by: kib
MFC after: 1 week

vfs: Fix "emptydir" mount option

Fix vfs_emptydir(). It would consider directories containing directories
with name of the form 'X.' (X being any authorized byte) as empty. Also,
it would cause VOP_

vfs: Fix "emptydir" mount option

Fix vfs_emptydir(). It would consider directories containing directories
with name of the form 'X.' (X being any authorized byte) as empty. Also,
it would cause VOP_READDIR() to return an error on directories
containing enough whiteouts. While here, use a more decently sized
buffer as done elsewhere.

Remove ad-hoc iteration on the directory's content and instead use the
newly exported vn_dir_next_dirent() function (this is what fixes the
second problem mentioned above).

PR: 270988
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D39775

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syncer vnode: add VOP_GETWRITEMOUNT() definition explicitly

Since syncer vnode vector does not provide a fallback to the default
one, its VOP_GETWRITEMOUNT() implementation implicitly returned
EOPNO

syncer vnode: add VOP_GETWRITEMOUNT() definition explicitly

Since syncer vnode vector does not provide a fallback to the default
one, its VOP_GETWRITEMOUNT() implementation implicitly returned
EOPNOTSUPP, which means that syncer ignored suspension.

Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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sync_vnode(): add assert to check vn_start_write() correctness

Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

DEBUG_VFS_LOCKS: restore diagnostic for the witness use case

Reviewed by: jah, markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.free

DEBUG_VFS_LOCKS: restore diagnostic for the witness use case

Reviewed by: jah, markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D39477

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DEBUG_VFS_LOCKS: use witness if available

The assert_vop_locked messages are ignored, and file/line information
is not too useful. Fixing this without changing both witness and VFS
asserts KPIs is n

DEBUG_VFS_LOCKS: use witness if available

The assert_vop_locked messages are ignored, and file/line information
is not too useful. Fixing this without changing both witness and VFS
asserts KPIs is not possible.

Reviewed by: markj (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D39464

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vfs: extend vn_printf with vop vector

vfs: more informative panic for missing fplookup ops

vfs: validate that a mount point with FPLOOKUP has vop_fplookup ops

vfs: only allow doomed vnodes to return EOPNOTSUPP for fplookup vops

This helps asserting that they are provided by filesystems indicating
they do it.

vfs: add missing vop_fplookup ops to syncer

vfs: whack spurious comments from syncer's vop_vector

vfs: trylock vnode requeue

The quasi-LRU still gets in the way for example when doing an
incremental bzImage build, with vnode_list lock being at the
top of the profile. Further damage control the p

vfs: trylock vnode requeue

The quasi-LRU still gets in the way for example when doing an
incremental bzImage build, with vnode_list lock being at the
top of the profile. Further damage control the problem by trylocking.

Note the entire mechanism desperately wants to be reaped out in favor
of something(tm) which both scales in a multicore setting and provides
sensible replacement policy.

With this change everything vfs almost disappears from the on CPU
flamegraph, what is left is tons of contention in the VM.

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vfs: flip deferred_inact to atomic

Turns out it is very rarely triggered, making a per-cpu
counter a waste.

Examples from real life boxes:
uptime counter
135 days 847
138 days 2190
141 days 1

vfs: replace some spelled out VNASSERTs with VNPASS

nfc