the dm_lock is held while the newly allocated vnode is locked. Since no
other threads may try to lock the new vnode yet, the LOR there cannot
result in the deadlock.
Shut down the witness warning to note this fact.
Tested by: pho
Prodded by: attilio
As discussed with Robert Watson and John Baldwin, it would be better if
PTY's are created with proper permissions, turning grantpt() into a
no-op.
Bypassing security frameworks like MAC by passing NOCRED to
VOP_SETATTR() will only make things more complex.
Approved by: philip (mentor)
In the mpsafetty branch, PTY's are allocated through the posix_openpt()
system call. The controller side of a PTY now uses its own file
descriptor type (just like sockets, vnodes, pipes, etc).
To remain compatible with existing FreeBSD and Linux C libraries, we can
still create PTY's by opening /dev/ptmx or /dev/ptyXX. These nodes
implement d_fdopen(). Devfs has been slightly changed here, to allow
finit() to be called from d_fdopen().
The routine grantpt() has also been moved into the kernel. This routine
is a little odd, because it needs to bypass standard UNIX permissions.
It needs to change the owner/group/mode of the slave device node, which
may often not be possible. The old implementation solved this by
spawning a setuid utility.
When VOP_SETATTR() is called with NOCRED, devfs_setattr() dereferences
ap->a_cred, causing a kernel panic. Change the de_{uid,gid,mode} code to
allow changes when a->a_cred is set to NOCRED.
Approved by: philip (mentor)
- Use proper synhronization primitives to protect the internal fdesc node cache
used in fdescfs.
- Properly initialize and uninitalize hash.
- Remove unused functions.
Since fdescfs might recurse on itself, adding proper locking to it needed some
tricky workarounds in some parts to make it work. For instance, a descriptor in
fdescfs could refer to an open descriptor to itself, thus forcing the thread to
recurse on vnode locks. Because of this, other race conditions also had to be
fixed.
Tested by: pho
Reviewed by: kib (mentor)
Approved by: kib (mentor)
sense to loop trying to vget() the vnode again.
PR: 122977
Submitted by: Arthur Hartwig <arthur.hartwig nokia com>
Tested by: pho
Reviewed by: jhb
MFC after: 1 week
The patch does not change the cdevsw KBI. Management of the data is
provided by the functions
int devfs_set_cdevpriv(void *priv, cdevpriv_dtr_t dtr);
int devfs_get_cdevpriv(void **datap);
void devfs_clear_cdevpriv(void);
All of the functions are supposed to be called from the cdevsw method
contexts.
- devfs_set_cdevpriv assigns the priv as private data for the file
descriptor which is used to initiate currently performed driver
operation. dtr is the function that will be called when either the
last refernce to the file goes away, the device is destroyed or
devfs_clear_cdevpriv is called.
- devfs_get_cdevpriv is the obvious accessor.
- devfs_clear_cdevpriv allows to clear the private data for the still
open file.
Implementation keeps the driver-supplied pointers in the struct
cdev_privdata, that is referenced both from the struct file and struct
cdev, and cannot outlive any of the referee.
Man pages will be provided after the KPI stabilizes.
Reviewed by: jhb
Useful suggestions from: jeff, antoine
Debugging help and tested by: pho
MFC after: 1 month
the mentioned PR:
- bounds check time->month as it is used as an array index
- fix usage of time->month as array index (month is 1-12)
- fix calculation based on time->day (day is 1-31)
- fix the speedup code as it doesn't calculate correct timestamps before
the year 2000 and reduce the number of calculation in the year-by-year code
- speedup month calculations by replacing the array content with cumulative
values
- add microseconds calculation
- fix an endian problem
PR: kern/97786
Submitted by: Andriy Gapon <avg@topspin.kiev.ua>
Reviewed by: scottl (earlier version)
Approved by: emax (mentor)
MFC after: 1 week
VSOCK has been added as cache target. Now they process
not only VDIR but also VSOCK.
- fixed panic issue caused by cache incorrect free process
by "umount -f"
Submitted by: Masanori OZAWA <ozawa@ongs.co.jp>
MFC after: 1 week
filesystem-specific vnode data to the struct vnode. Provide the
default implementation for the vop_advlock and vop_advlockasync.
Purge the locks on the vnode reclaim by using the lf_purgelocks().
The default implementation is augmented for the nfs and smbfs.
In the nfs_advlock, push the Giant inside the nfs_dolock.
Before the change, the vop_advlock and vop_advlockasync have taken the
unlocked vnode and dereferenced the fs-private inode data, racing with
with the vnode reclamation due to forced unmount. Now, the vop_getattr
under the shared vnode lock is used to obtain the inode size, and
later, in the lf_advlockasync, after locking the vnode interlock, the
VI_DOOMED flag is checked to prevent an operation on the doomed vnode.
The implementation of the lf_purgelocks() is submitted by dfr.
Reported by: kris
Tested by: kris, pho
Discussed with: jeff, dfr
MFC after: 2 weeks
state transitioning flags and of msleep(9) callings.
Use, instead, an algorithm very similar to what sx(9) and rwlock(9)
alredy do and direct accesses to the sleepqueue(9) primitive.
In order to avoid writer starvation a mechanism very similar to what
rwlock(9) uses now is implemented, with the correspective per-thread
shared lockmgrs counter.
This patch also adds 2 new functions to lockmgr KPI: lockmgr_rw() and
lockmgr_args_rw(). These two are like the 2 "normal" versions, but they
both accept a rwlock as interlock. In order to realize this, the general
lockmgr manager function "__lockmgr_args()" has been implemented through
the generic lock layer. It supports all the blocking primitives, but
currently only these 2 mappers live.
The patch drops the support for WITNESS atm, but it will be probabilly
added soon. Also, there is a little race in the draining code which is
also present in the current CVS stock implementation: if some sharers,
once they wakeup, are in the runqueue they can contend the lock with
the exclusive drainer. This is hard to be fixed but the now committed
code mitigate this issue a lot better than the (past) CVS version.
In addition assertive KA_HELD and KA_UNHELD have been made mute
assertions because they are dangerous and they will be nomore supported
soon.
In order to avoid namespace pollution, stack.h is splitted into two
parts: one which includes only the "struct stack" definition (_stack.h)
and one defining the KPI. In this way, newly added _lockmgr.h can
just include _stack.h.
Kernel ABI results heavilly changed by this commit (the now committed
version of "struct lock" is a lot smaller than the previous one) and
KPI results broken by lockmgr_rw() / lockmgr_args_rw() introduction,
so manpages and __FreeBSD_version will be updated accordingly.
Tested by: kris, pho, jeff, danger
Reviewed by: jeff
Sponsored by: Google, Summer of Code program 2007
the fdesc_allocvp(). The caller of the fdesc_allocvp() expects that the
returned vnode is not reclaimed. Do lock the vnode exclusive and drop
the lock after.
Reported by: pho
Reviewed by: jeff
user-mode lock manager, build a kernel with the NFSLOCKD option and
add '-k' to 'rpc_lockd_flags' in rc.conf.
Highlights include:
* Thread-safe kernel RPC client - many threads can use the same RPC
client handle safely with replies being de-multiplexed at the socket
upcall (typically driven directly by the NIC interrupt) and handed
off to whichever thread matches the reply. For UDP sockets, many RPC
clients can share the same socket. This allows the use of a single
privileged UDP port number to talk to an arbitrary number of remote
hosts.
* Single-threaded kernel RPC server. Adding support for multi-threaded
server would be relatively straightforward and would follow
approximately the Solaris KPI. A single thread should be sufficient
for the NLM since it should rarely block in normal operation.
* Kernel mode NLM server supporting cancel requests and granted
callbacks. I've tested the NLM server reasonably extensively - it
passes both my own tests and the NFS Connectathon locking tests
running on Solaris, Mac OS X and Ubuntu Linux.
* Userland NLM client supported. While the NLM server doesn't have
support for the local NFS client's locking needs, it does have to
field async replies and granted callbacks from remote NLMs that the
local client has contacted. We relay these replies to the userland
rpc.lockd over a local domain RPC socket.
* Robust deadlock detection for the local lock manager. In particular
it will detect deadlocks caused by a lock request that covers more
than one blocking request. As required by the NLM protocol, all
deadlock detection happens synchronously - a user is guaranteed that
if a lock request isn't rejected immediately, the lock will
eventually be granted. The old system allowed for a 'deferred
deadlock' condition where a blocked lock request could wake up and
find that some other deadlock-causing lock owner had beaten them to
the lock.
* Since both local and remote locks are managed by the same kernel
locking code, local and remote processes can safely use file locks
for mutual exclusion. Local processes have no fairness advantage
compared to remote processes when contending to lock a region that
has just been unlocked - the local lock manager enforces a strict
first-come first-served model for both local and remote lockers.
Sponsored by: Isilon Systems
PR: 95247 107555 115524 116679
MFC after: 2 weeks
BO_LOCK/UNLOCK/MTX when manipulating the bufobj.
- Create a new lock in the bufobj to lock bufobj fields independently.
This leaves the vnode interlock as an 'identity' lock while the bufobj
is an io lock. The bufobj lock is ordered before the vnode interlock
and also before the mnt ilock.
- Exploit this new lock order to simplify softdep_check_suspend().
- A few sync related functions are marked with a new XXX to note that
we may not properly interlock against a non-zero bv_cnt when
attempting to sync all vnodes on a mountlist. I do not believe this
race is important. If I'm wrong this will make these locations easier
to find.
Reviewed by: kib (earlier diff)
Tested by: kris, pho (earlier diff)
obtain the reference. In particular, this fixes the panic reported in
the PR. Remove the comments stating that this needs to be done.
PR: kern/119422
MFC after: 1 week
While the KSE project was quite successful in bringing threading to
FreeBSD, the M:N approach taken by the kse library was never developed
to its full potential. Backwards compatibility will be provided via
libmap.conf for dynamically linked binaries and static binaries will
be broken.
than rely on the lockmgr support [1]:
* bump the waiters only if the interlock is held
* let brelvp() return the waiters count
* rely on brelvp() instead than BUF_LOCKWAITERS() in order to check
for the waiters number
- Remove a namespace pollution introduced recently with lockmgr.h
including lock.h by including lock.h directly in the consumers and
making it mandatory for using lockmgr.
- Modify flags accepted by lockinit():
* introduce LK_NOPROFILE which disables lock profiling for the
specified lockmgr
* introduce LK_QUIET which disables ktr tracing for the specified
lockmgr [2]
* disallow LK_SLEEPFAIL and LK_NOWAIT to be passed there so that it
can only be used on a per-instance basis
- Remove BUF_LOCKWAITERS() and lockwaiters() as they are no longer
used
This patch breaks KPI so __FreBSD_version will be bumped and manpages
updated by further commits. Additively, 'struct buf' changes results in
a disturbed ABI also.
[2] Really, currently there is no ktr tracing in the lockmgr, but it
will be added soon.
[1] Submitted by: kib
Tested by: pho, Andrea Barberio <insomniac at slackware dot it>
always curthread.
As KPI gets broken by this patch, manpages and __FreeBSD_version will be
updated by further commits.
Tested by: Andrea Barberio <insomniac at slackware dot it>
namespace in order to handle lockmgr fields in a controlled way instead
than spreading all around bogus stubs:
- VN_LOCK_AREC() allows lock recursion for a specified vnode
- VN_LOCK_ASHARE() allows lock sharing for a specified vnode
In FFS land:
- BUF_AREC() allows lock recursion for a specified buffer lock
- BUF_NOREC() disallows recursion for a specified buffer lock
Side note: union_subr.c::unionfs_node_update() is the only other function
directly handling lockmgr fields. As this is not simple to fix, it has
been left behind as "sole" exception.
macros. The only semantic change was the need to add a vc_opened field
to struct vcomm since we can no longer use the request queue returning
to an uninitialized state to hold whether or not the device is open.
MFC after: 1 month
fundamentally fairly confused about how signals work and when it is
appropriate for upcalls to be interrupted. In particular, we should
be exempting certain upcalls from interruption, we should not always
eventually time out sleeping on a upcall, and we should not be
interrupting the sleep for certain signals that we currently are
(including SIGINFO). This code needs to be reworked in the style of
NFS interruptible mounts.
MFC after: 1 month
access cache improvements:
- Flush just access control state on CODA_PURGEUSER, not the full
namecache for /coda.
- When replacing a fid on a cnode as a result of, e.g.,
reintegration after offline operation, we no longer need to
purge the namecache entries associated with its vnode.
MFC after: 1 month
modeled on the access cache found in NFS, smbfs, and the Linux coda
module. This is a positive access cache of a single entry per file,
tracking recently granted rights, but unlike NFS and smbfs,
supporting explicit invalidation by the distributed file system.
For each cnode, maintain a C_ACCCACHE flag indicating the validity
of the cache, and a cached uid and mode tracking recently granted
positive access control decisions.
Prefer the cache to venus_access() in VOP_ACCESS() if it is valid,
and when we must fall back to venus_access(), update the cache.
Allow Venus to clear the access cache, either the whole cache on
CODA_FLUSH, or just entries for a specific uid on CODA_PURGEUSER.
Unlike the Coda module on Linux, we don't flush all entries on a
user purge using a generation number, we instead walk present
cnodes and clear only entries for the specific user, meaning it is
somewhat more expensive but won't hit all users.
Since the Coda module is agressive about not keeping around
unopened cnodes, the utility of the cache is somewhat limited for
files, but works will for directories. We should make Coda less
agressive about GCing cnodes in VOP_INACTIVE() in order to improve
the effectiveness of in-kernel caching of attributes and access
rights.
MFC after: 1 month
VFS namecache, as is done by the Coda module on Linux. Unlike the Coda
namecache, the global VFS namecache isn't tagged by credential, so use
ore conservative flushing behavior (for now) when CODA_PURGEUSER is
issued by Venus.
This improves overall integration with the FreeBSD VFS, including
allowing __getcwd() to work better, procfs/procstat monitoring, and so
on. This improves shell behavior in many cases, and improves ".."
handling. It may lead to some slowdown until we've implemented a
specific access cache, which should net improve performance, but in the
mean time, lookup access control now always goes to Venus, whereas
previously it didn't.
MFC after: 1 month
When ntfs_ntput() reaches 0 in the refcount the inode lockmgr is not
released and directly destroyed. Fix this by unlocking the lockmgr() even
in the case of zero-refcount.
Reported by: dougb, yar, Scot Hetzel <swhetzel at gmail dot com>
Submitted by: yar
tree, restyle everything but coda.h (which is more explicitly shared
across systems) into a closer approximation to style(9).
Remove a few more unused function prototypes.
Add or clarify some comments.
MFC after: 1 month
- Rename print_vattr to coda_print_vattr and make static, rename
print_cred to coda_print_cred.
- Remove unused coda_vop_nop.
- Add XXX comment because coda_readdir forwards to the cache vnode's
readdir rather than venus_readdir, and annotate venus_readdir as
unused.
- Rename vc_nb_* to vc_*.
- Use d_open_t, d_close_t, d_read_t, d_write_t, d_ioctl_t and d_poll_t
for prototyping vc_* as that is the intent, don't use our own
definitions.
- Rename coda_nb_statfs to coda_statfs, rename NB_SFS_SIZ to
CODA_SFS_SIZ.
- Replace one more OBE reference to NetBSD with a reference to FreeBSD.
- Tidy up a little vertical whitespace here and there.
- Annotate coda_nc_zapvnode as unused.
- Remove unused vcodattach.
- Annotate VM_INTR as unused.
- Annotate that coda_fhtovp is unused and doesn't match the FreeBSD
prototype, so isn't hooked up to vfs_fhtovp. If we want NFS export of
Coda to work someday, this needs to be fixed.
- Remove unused getNewVnode.
- Remove unused coda_vget, coda_init, coda_quotactl prototypes.
MFC after: 1 month
the mountpoint for a specific device. This was implemented incorrectly,
a bad idea in a fundamental sense, and also never used, so presumably
a long-idle debugging function.
MFC after: 1 month
