vm_ooffset_t is now unsigned. Remove some tests for negative values,
or make other adjustments accordingly.
Reported by: Coverity
Reviewed by: kib markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D26214
Split TMPFS_NODE_ACCCESSED bit into dedicated byte that can be updated
atomically without locks or (locked) atomics.
tn_update_getattr() change also contains unrelated bug fix.
Reported by: lwhsu
PR: 249362
Reviewed by: markj (previous version)
Discussed with: mjg
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D26451
Or it could be explained as lockless (for vnode lock) reads. Reads
are performed from the node tn_obj object. Tmpfs regular vnode object
lifecycle is significantly different from the normal OBJT_VNODE: it is
alive as far as ref_count > 0.
Ensure liveness of the tmpfs VREG node and consequently v_object
inside VOP_READ_PGCACHE by referencing tmpfs node in tmpfs_open().
Provide custom tmpfs fo_close() method on file, to ensure that close
is paired with open.
Add tmpfs VOP_READ_PGCACHE that takes advantage of all tmpfs quirks.
It is quite cheap in code size sense to support page-ins for read for
tmpfs even if we do not own tmpfs vnode lock. Also, we can handle
holes in tmpfs node without additional efforts, and do not have
limitation of the transfer size.
Reviewed by: markj
Discussed with and benchmarked by: mjg (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D26346
Avoid tmpfs mount and node locks when ref count is greater than zero,
which is the case until node is being destroyed by unlink or unmount.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D26346
All vm_object_page_remove() callers, except
linux_invalidate_mapping_pages() in the LinuxKPI, free swap space when
removing a range of pages from an object. The LinuxKPI case appears to
be an unintentional omission that could result in leaked swap blocks, so
unconditionally free swap space in vm_object_page_remove() to protect
against similar bugs in the future.
Reviewed by: alc, kib
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D25329
r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.
This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.
Mark all obvious cases as MPSAFE. All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT
Approved by: kib (mentor, blanket)
Commented by: kib, gallatin, melifaro
Differential Revision: https://reviews.freebsd.org/D23718
It was generated to be just a jumping off point to tmpfs_itimes.
While here provide a dedicated variant for getattr since we normally don't
expect to need to the update from that caller.
The vnode pager does not want the object lock held. Moving this out allows
further object lock scope reduction in callers. While here add some missing
paging in progress calls and an assert. The object handle is now protected
explicitly with pip.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D23033
With the previous reviews, the page lock is no longer required in order
to perform queue operations on a page. It is also no longer needed in
the page queue scans. This change effectively eliminates remaining uses
of the page lock and also the false sharing caused by multiple pages
sharing a page lock.
Reviewed by: jeff
Tested by: pho
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D22885
an exclusive object lock.
Previously swap space was freed on a best effort basis when a page that
had valid swap was dirtied, thus invalidating the swap copy. This may be
done inconsistently and requires the object lock which is not always
convenient.
Instead, track when swap space is present. The first dirty is responsible
for deleting space or setting PGA_SWAP_FREE which will trigger background
scans to free the swap space.
Simplify the locking in vm_fault_dirty() now that we can reliably identify
the first dirty.
Discussed with: alc, kib, markj
Differential Revision: https://reviews.freebsd.org/D22654
Both of these features are not needed by many consumers and result in avoidable
reads which in turn puts them on profiles due to cache-line ping ponging.
On top of that the current lockgmr entry point is slower than necessary
single-threaded. As an attempted clean up preparing for other changes,
provide new routines which don't support any of the aforementioned features.
With these patches in place vop_stdlock and vop_stdunlock disappear from
flamegraphs during -j 104 buildkernel.
Reviewed by: jeff (previous version)
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22665
The current vnode layout is not smp-friendly by having frequently read data
avoidably sharing cachelines with very frequently modified fields. In
particular v_iflag inspected for VI_DOOMED can be found in the same line with
v_usecount. Instead make it available in the same cacheline as the v_op, v_data
and v_type which all get read all the time.
v_type is avoidably 4 bytes while the necessary data will easily fit in 1.
Shrinking it frees up 3 bytes, 2 of which get used here to introduce a new
flag field with a new value: VIRF_DOOMED.
Reviewed by: kib, jeff
Differential Revision: https://reviews.freebsd.org/D22715
reudundant complicated checks and additional locking required only for
anonymous memory. Introduce vm_object_allocate_anon() to create these
objects. DEFAULT and SWAP objects now have the correct settings for
non-anonymous consumers and so individual consumers need not modify the
default flags to create super-pages and avoid ONEMAPPING/NOSPLIT.
Reviewed by: alc, dougm, kib, markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22119
flag and use the same system.
This enables further fault locking improvements by allowing more faults to
proceed with a shared lock.
Reviewed by: kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22116
Atomics are used for page busy and valid state when the shared busy is
held. The details of the locking protocol and valid and dirty
synchronization are in the updated vm_page.h comments.
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D21594
This is the first in a series of patches that promotes the page busy field
to a first class lock that no longer requires the object lock for
consistency.
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D21548
During readdir() we guarantee that the tn_dir.tn_parent does not go
away, but it might be replaced by a parallel rename. Read tn_parent
only once, then use the cached value.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
There are 3 counters modified all the time in this structure - one for
keeping the structure alive, one for preventing unmount and one for
tracking active writers. Exact values of these counters are very rarely
needed, which makes them a prime candidate for conversion to a per-cpu
scheme, resulting in much better performance.
Sample benchmark performing fstatfs (modifying 2 out of 3 counters) on
a 104-way 2 socket Skylake system:
before: 852393 ops/s
after: 76682077 ops/s
Reviewed by: kib, jeff
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21637
There are several mechanisms by which a vm_page reference is held,
preventing the page from being freed back to the page allocator. In
particular, holding the page's object lock is sufficient to prevent the
page from being freed; holding the busy lock or a wiring is sufficent as
well. These references are protected by the page lock, which must
therefore be acquired for many per-page operations. This results in
false sharing since the page locks are external to the vm_page
structures themselves and each lock protects multiple structures.
Transition to using an atomically updated per-page reference counter.
The object's reference is counted using a flag bit in the counter. A
second flag bit is used to atomically block new references via
pmap_extract_and_hold() while removing managed mappings of a page.
Thus, the reference count of a page is guaranteed not to increase if the
page is unbusied, unmapped, and the object's write lock is held. As
a consequence of this, the page lock no longer protects a page's
identity; operations which move pages between objects are now
synchronized solely by the objects' locks.
The vm_page_wire() and vm_page_unwire() KPIs are changed. The former
requires that either the object lock or the busy lock is held. The
latter no longer has a return value and may free the page if it releases
the last reference to that page. vm_page_unwire_noq() behaves the same
as before; the caller is responsible for checking its return value and
freeing or enqueuing the page as appropriate. vm_page_wire_mapped() is
introduced for use in pmap_extract_and_hold(). It fails if the page is
concurrently being unmapped, typically triggering a fallback to the
fault handler. vm_page_wire() no longer requires the page lock and
vm_page_unwire() now internally acquires the page lock when releasing
the last wiring of a page (since the page lock still protects a page's
queue state). In particular, synchronization details are no longer
leaked into the caller.
The change excises the page lock from several frequently executed code
paths. In particular, vm_object_terminate() no longer bounces between
page locks as it releases an object's pages, and direct I/O and
sendfile(SF_NOCACHE) completions no longer require the page lock. In
these latter cases we now get linear scalability in the common scenario
where different threads are operating on different files.
__FreeBSD_version is bumped. The DRM ports have been updated to
accomodate the KPI changes.
Reviewed by: jeff (earlier version)
Tested by: gallatin (earlier version), pho
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20486
Both filesystems do no use vnode_pager_dealloc() which would handle
this case otherwise. Nullfs because vnode vm_object handle never
points to nullfs vnode. Tmpfs because its vm_object is never vnode
object at all.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
In particular, this fixes atimes still changing for ro tmpfs.
tmpfs_set_status() gains tmpfs_mount * argument.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D19737
Directory entries must be padded to maintain alignment; in many
filesystems the padding was not initialized, resulting in stack
memory being copied out to userspace. With the ino64 work there
are also some explicit pad fields in struct dirent. Add a subroutine
to clear these bytes and use it in the in-tree filesystems. The
NFS client is omitted for now as it was fixed separately in r340787.
Reported by: Thomas Barabosch, Fraunhofer FKIE
Reviewed by: kib
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
This will enable callers to take const paths as part of syscall
decleration improvements.
Where doing so is easy and non-distruptive carry the const through
implementations. In UFS the value is passed to an interface that must
take non-const values. In ZFS, const poisoning would touch code shared
with upstream and it's not worth adding diffs.
Bump __FreeBSD_version for external API consumers.
Reviewed by: kib (prior version)
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D17805
given in random(4).
This includes updating of the relevant man pages, and no-longer-used
harvesting parameters.
Ensure that the pseudo-unit-test still does something useful, now also
with the "other" algorithm instead of Yarrow.
PR: 230870
Reviewed by: cem
Approved by: so(delphij,gtetlow)
Approved by: re(marius)
Differential Revision: https://reviews.freebsd.org/D16898
global to per-domain state. Protect reservations with the free lock
from the domain that they belong to. Refactor to make vm domains more
of a first class object.
Reviewed by: markj, kib, gallatin
Tested by: pho
Sponsored by: Netflix, Dell/EMC Isilon
Differential Revision: https://reviews.freebsd.org/D14000
Add a new TMPFS_LINK_MAX to use in place of LINK_MAX for link overflow
checks and pathconf() reporting. Rather than storing a full 64-bit
link count, just use a plain int and use INT_MAX as TMPFS_LINK_MAX.
Discussed with: bde
Reviewed by: kib (part of a larger patch)
Sponsored by: Chelsio Communications
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
similar to the kernel memory allocator.
This simplifies NUMA allocation because the domain will be known at wait
time and races between failure and sleeping are eliminated. This also
reduces boilerplate code and simplifies callers.
A wait primitive is supplied for uma zones for similar reasons. This
eliminates some non-specific VM_WAIT calls in favor of more explicit
sleeps that may be satisfied without new pages.
Reviewed by: alc, kib, markj
Tested by: pho
Sponsored by: Netflix, Dell/EMC Isilon
tmpfs uses unr(9) to allocate inodes. Previously when unmounting it
would individually free the units when it freed each vnode. This is
unnecessary as we can use the newly-added unrhdr_clear function to clear
out the unr in onde go. This measurably reduces the time to unmount a
tmpfs with many files.
Reviewed by: cem, lidl
Approved by: rstone (mentor)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D12591
Such updates consisted of vast majority of modificiations, especially
in tmpfs_reg_resize.
For the case where page count did no change and the size grew we only
need to update tn_size. Use this fact to avoid vm object lock/relock.
MFC after: 1 week
The option "nonc" disables using of namecache for the created mount,
by default namecache is used. The rationale for the option is that
namecache duplicates the information which is already kept in memory
by tmpfs. Since it believed that namecache scales better than tmpfs,
or will scale better, do not enable the option by default. On the
other hand, smaller machines may benefit from lesser namecache
pressure.
Discussed with: mjg
Tested by: pho (as part of larger patch)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
On dotdot lookup and fhtovp operations, it is possible for the file
represented by tmpfs node to be removed after the thread calculated
the pointer. In this case, tmpfs_alloc_vp() accesses freed memory.
Introduce the reference count on the nodes. The allnodes list from
tmpfs mount owns 1 reference, and threads performing unlocked
operations on the node, add one transient reference. Similarly, since
struct tmpfs_mount maintains the list where nodes are enlisted,
refcount it by one reference from struct mount and one reference from
each node on the list. Both nodes and tmpfs_mounts are removed when
refcount goes to zero.
Note that this means that nodes and tmpfs_mounts might survive some
time after the node is deleted or tmpfs_unmount() finished. The
tmpfs_alloc_vp() in these cases returns error either due to node
removal (tn_nlinks == 0) or because of insmntque1(9) error.
Tested by: pho (as part of larger patch)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Remove TMPFS_ASSERT_ELOCKED(). Its claims are already stated by other
asserts nearby and by VFS guarantees.
Change TMPFS_ASSERT_LOCKED() and one inlined place to use
ASSERT_VOP_(E)LOCKED() instead of hand-rolled imprecise asserts.
Tested by: pho (as part of the larger patch)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Edit comments which explain no longer relevant details, and add
locking annotations to the struct tmpfs_node members.
Tested by: pho (as part of the larger patch)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
