Some watchdog drivers (like ipmi) need to sleep while patting the watchdog.
See sys/dev/ipmi/ipmi.c:ipmi_wd_event(), which calls malloc(M_WAITOK).
Submitted by: asomers
MFC after: 1 month
Sponsored by: Spectra Logic
MFSpectraBSD: 637548 on 2012/10/04
It could be claimed that two things were reasonable protected by
Giant. One is vfsconf list links, which is converted to the new
dedicated sx vfsconf_sx. Another is vfsconf.vfc_refcount, which is
now updated with atomics.
Note that vfc_refcount still has the same races now as it has under
the Giant, the unload of filesystem modules can happen while the
module is still in use.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
some parts of the checks are in fact redundand in the surrounding
code, and it is more clear what the conditions are by direct testing
of the flags. Two of the three macros were only used in assertions.
In vnlru_free(), all relevant parts of vholdl() were already inlined,
except the increment of v_holdcnt itself. Do not call vholdl() to do
the increment as well, this allows to make assertions in
vholdl()/vhold() more strict.
In v_incr_usecount(), call vholdl() before incrementing other ref
counters. The change is no-op, but it makes less surprising to see
the vnode state in debugger if interrupted inside v_incr_usecount().
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
avoid congestion on global mountlist_mtx mutex in vfs_busyfs(), while
traversing through the list of mount points.
This change significantly improves NFS server scalability, since it had
to do this translation for every request, and the global lock becomes quite
congested.
This code is more optimized for relatively small number of mount points.
On systems with hundreds of active mount points this simple cache may have
many collisions. But the original traversal code in that case should also
behave much worse, so we are not loosing much.
Reviewed by: attilio
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
This allows to mostly avoid lock usage in getnewvnode_[drop_]reserve(),
that reduces number of global vnode_free_list_mtx mutex acquisitions
from 4 to 2 per NFS request on ZFS, improving SMP scalability.
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
Assert that the hold count has not fallen below the use count, a situation
that would only happen when a vref() (or similar) is erroneously paired
with a vdrop(). This situation has not been observed in the wild, but
could be helpful for someone implementing a new filesystem.
Reviewed by: kib
Approved by: hrs (mentor)
To reduce the diff struct pcu.cnt field was not renamed, so
PCPU_OP(cnt.field) is still used. pc_cnt and pcpu are also used in
kvm(3) and vmstat(8). The goal was to not affect externally used KPI.
Bump __FreeBSD_version_ in case some out-of-tree module/code relies on the
the global cnt variable.
Exp-run revealed no ports using it directly.
No objection from: arch@
Sponsored by: EMC / Isilon Storage Division
really belong to it. Such vnodes, with the pointers to other vnodes
v_objects, are typically instantiated by the bypass filesystems.
Invalidating mappings of other vnode pages and the pages is wrong,
since reclamation of the upper vnode does not imply that lower vnode
is reclaimed too.
One of the consequences of the improper reclamation was destruction of
the wired mappings of the lower vnode pages, triggering miscellaneous
assertions in the VM system.
Reported by: John Marshall <john.marshall@riverwillow.com.au>
Tested by: John Marshall <john.marshall@riverwillow.com.au>, pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Approved by: re (gjb)
with the vnode shared-locked. If upgrade succeeded, the inactivation
can be done immediately, instead of being postponed.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Approved by: re (glebius)
Otherwise, knote keeps a pointer to a vnode which could become invalid
any time.
Reported by: many
Tested by: Patrick Lamaiziere <patfbsd@davenulle.org>
Discussed with: jmg
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Approved by: re (marius)
must be destroyed, knlist_clear() and seldrain() calls could be
avoided, since vpollinfo was not used. More, the knlist_clear()
calling protocol requires the knlist locked, which is not true at the
call site.
Split the destruction into the helper destroy_vpollinfo_free(), and
call it when raced, instead of destroy_vpollinfo().
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
the vnode lock while iterating over the free vnode list. Instead of
yielding, pause for 1 tick. The change is reported to help in some
virtualized environments.
Submitted by: Roger Pau Monn? <roger.pau@citrix.com>
Discussed with: jilles
Tested by: pho
MFC after: 2 weeks
- Use a shared bufobj lock in getblk() and inmem().
- Convert softdep's lk to rwlock to match the bufobj lock.
- Move INFREECNT to b_flags and protect it with the buf lock.
- Remove unnecessary locking around bremfree() and BKGRDINPROG.
Sponsored by: EMC / Isilon Storage Division
Discussed with: mckusick, kib, mdf
with any structure containing a uint64_t index. The tree code
auto-generates type safe wrappers.
- Eliminate the buf splay and replace it with pctrie. This is not only
significantly faster with large files but also allows for the possibility
of shared locking.
Reviewed by: alc, attilio
Sponsored by: EMC / Isilon Storage Division
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
locks. To support this, VNODE locks are created with the LK_IS_VNODE
flag. This flag is propagated down using the LO_IS_VNODE flag.
Note that WITNESS still records the LOR. Only the printing and the
optional entering into the kernel debugger is bypassed with the
WITNESS_NO_VNODE option.
LK_EXCLOTHER. LK_EXCLOTHER is only used to acquire a
usecount on a vnode during NFSv4 recovery from an
expired lease.
Reported and tested by: pho
MFC after: 2 weeks
- Don't insert BKGRDMARKER bufs into the splay or dirty/clean buf lists.
No consumers need to find them there and it complicates the tree.
These flags are all FFS specific and could be moved out of the buf
cache.
- Use pbgetvp() and pbrelvp() to associate the background and journal
bufs with the vp. Not only is this much cheaper it makes more sense
for these transient bufs.
- Fix the assertions in pbget* and pbrel*. It's not safe to check list
pointers which were never initialized. Use the BX flags instead. We
also check B_PAGING in reassignbuf() so this should cover all cases.
Discussed with: kib, mckusick, attilio
Sponsored by: EMC / Isilon Storage Division
future further optimizations where the vm_object lock will be held
in read mode most of the time the page cache resident pool of pages
are accessed for reading purposes.
The change is mostly mechanical but few notes are reported:
* The KPI changes as follow:
- VM_OBJECT_LOCK() -> VM_OBJECT_WLOCK()
- VM_OBJECT_TRYLOCK() -> VM_OBJECT_TRYWLOCK()
- VM_OBJECT_UNLOCK() -> VM_OBJECT_WUNLOCK()
- VM_OBJECT_LOCK_ASSERT(MA_OWNED) -> VM_OBJECT_ASSERT_WLOCKED()
(in order to avoid visibility of implementation details)
- The read-mode operations are added:
VM_OBJECT_RLOCK(), VM_OBJECT_TRYRLOCK(), VM_OBJECT_RUNLOCK(),
VM_OBJECT_ASSERT_RLOCKED(), VM_OBJECT_ASSERT_LOCKED()
* The vm/vm_pager.h namespace pollution avoidance (forcing requiring
sys/mutex.h in consumers directly to cater its inlining functions
using VM_OBJECT_LOCK()) imposes that all the vm/vm_pager.h
consumers now must include also sys/rwlock.h.
* zfs requires a quite convoluted fix to include FreeBSD rwlocks into
the compat layer because the name clash between FreeBSD and solaris
versions must be avoided.
At this purpose zfs redefines the vm_object locking functions
directly, isolating the FreeBSD components in specific compat stubs.
The KPI results heavilly broken by this commit. Thirdy part ports must
be updated accordingly (I can think off-hand of VirtualBox, for example).
Sponsored by: EMC / Isilon storage division
Reviewed by: jeff
Reviewed by: pjd (ZFS specific review)
Discussed with: alc
Tested by: pho
Set the v_hash for a new vnode in the getnewvnode() to the value
calculated based on the vnode structure address. Filesystems using
vfs_hash_insert() override the v_hash using the standard formula of
(inode_number + mnt_hashseed). For other filesystems, the
initialization allows the vfs_hash_index() to provide useful hash too.
Suggested, reviewed and tested by: peter
Sponsored by: The FreeBSD Foundation
MFC after: 5 days
case. There is no point in optimizing further the code and use a TRUE
litteral for a path that does heavyweight stuff anyway (like lock acq),
at the price of obfuscated code.
Use the appropriate check where necessary and remove a macro.
Sponsored by: EMC / Isilon storage division
MFC after: 3 days
When kern_yield() was introduced with the possibility to specify
a new priority, the behaviour changed by not lowering priority at all
in the consumers, making the yielding mechanism highly ineffective for
high priority kthreads like bufdaemon, syncer, vlrudaemon, etc.
There are no evidences that consumers could bear with such change in
semantic and this situation could finally lead to bugs similar to the
ones fixed in r244240.
Re-specify userland pri for kthreads involved.
Tested by: pho
Reviewed by: kib, mdf
MFC after: 1 week
yields, specify the user priority for the yield. Otherwise, a
higher-priority (kernel) thread could fall into the priority-inversion
with the thread owning the mutex lock.
On single-processor machines or UP kernels, do not loop adaptively
when the next vnode cannot be locked, instead yield unconditionally.
Restructure the iteration initializer and the iterator to remove code
duplication. Put the code to fetch and lock a vnode next to the
current marker, into the mnt_vnode_next_active() function, and use it
instead of repeating the loop.
Reported by: hrs, rmacklem
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
kern_yield() is problematic than.
The owned mutex is the mount interlock, and it is in fact not needed
to guarantee the stability of the mount list of active vnodes, so fix
the the issue by only taking the mount interlock for MNT_REF and
MNT_REL operations.
While there, augment the unconditional yield by some amount of
spinning [1].
Reported and tested by: pho
Reviewed by: attilio
Submitted by: attilio [1]
MFC after: 3 days
over the active list. The mount interlock is not enough to guarantee
the validity of the tailq link pointers. The __mnt_vnode_next_active()
and __mnt_vnode_first_active() active lists iterators helper functions
did not provided the neccessary stability for the list, allowing the
iterators to pick garbage.
This was uncovered after the r243599 made the active list iterators
non-nop.
Since a vnode interlock is before the vnode_free_list_mtx, obtain the
vnode ilock in the non-blocking manner when under vnode_free_list_mtx,
and restart iteration after the yield if the lock attempt failed.
Assert that a vnode found on the list is active, and assert that the
helpers return the vnode with interlock owned.
Reported and tested by: pho
MFC after: 1 week
then:
- assume the lock is held in exclusive mode and remove a moot check
about the lock acquisition.
- in the destructor remove !MPSAFE specific chunk.
Reviewed by: kib
MFC after: 2 weeks
Also remove the checks from vop_lookup_pre and vop_lookup_post, which
are now completely redundant (before this change they were partially
redundant).
Discussed with: kib
MFC after: 10 days
In particular, do not lock Giant conditionally when calling into the
filesystem module, remove the VFS_LOCK_GIANT() and related
macros. Stop handling buffers belonging to non-mpsafe filesystems.
The VFS_VERSION is bumped to indicate the interface change which does
not result in the interface signatures changes.
Conducted and reviewed by: attilio
Tested by: pho
counter, without actually allocating the vnodes. The supposed use of
the getnewvnode_reserve(9) is to reclaim enough free vnodes while the
code still does not hold any resources that might be needed during the
reclamation, and to consume the slack later for getnewvnode() calls
made from the innards. After the critical block is finished, the
caller shall free any reserve left, by getnewvnode_drop_reserve(9).
Reviewed by: avg
Tested by: pho
MFC after: 1 week
trap checks (eg. printtrap()).
Generally this check is not needed anymore, as there is not a legitimate
case where curthread != NULL, after pcpu 0 area has been properly
initialized.
Reviewed by: bde, jhb
MFC after: 1 week
about vnode reclamation. Typical use is for the bypass mounts like
nullfs to get a notification about lower vnode going away.
Now, vgone() calls new VFS op vfs_reclaim_lowervp() with an argument
lowervp which is reclaimed. It is possible to register several
reclamation event listeners, to correctly handle the case of several
nullfs mounts over the same directory.
For the filesystem not having nullfs mounts over it, the overhead
added is a single mount interlock lock/unlock in the vnode reclamation
path.
In collaboration with: pho
MFC after: 3 weeks
for getvfsbyname(3) operation when called from 32bit process, and
getvfsbyname(3) is used by recent bsdtar import.
Reported by: many
Tested by: David Naylor <naylor.b.david@gmail.com>
MFC after: 5 days
