The reason this was done was to avoid a race to the root when an
NFS server went down. However a semi-recent change to the way that
the kernel's lookup() routine traverses mount points prevents this.
Rev 1.39 of vfs_lookup.c changed the ordering of locks such that we
aquire a shared lock on the mount point being accessed and then drop
the directory vnode lock before requesting the target lock.
With that in place we no longer need shared locks for NFS to prevent
race to the root lockups.
Introduce two new macros MNT_ILOCK(mp)/MNT_IUNLOCK(mp) to
operate on this mutex transparently.
Eventually new mutex will be protecting more fields in
struct mount, not only vnode list.
Discussed with: jeff
wasn't curthread, i.e. when we receive a thread pointer to use
as a function argument. Use VOP_UNLOCK/vrele in these cases.
The only case there td != curthread known at the moment is
boot() calling sync with thread0 pointer.
This fixes the panic on shutdown people have reported.
if_xname, if_dname, and if_dunit. if_xname is the name of the interface
and if_dname/unit are the driver name and instance.
This change paves the way for interface renaming and enhanced pseudo
device creation and configuration symantics.
Approved By: re (in principle)
Reviewed By: njl, imp
Tested On: i386, amd64, sparc64
Obtained From: NetBSD (if_xname)
VOP_INACTIVE routines need not worry about their vnode getting
recycled if they block. Remove the code from nfs_inactive() that
used vget() to get an extra vnode reference that was held during
the nfs_vinvalbuf() call.
stack trace supplied by phk, I now understand what's going on here. The
check for VI_XLOCK stops us from calling vinvalbuf once the vnode has been
partially torn down in vclean(). It is not clear that this would cause
a problem. Document this in nfs_bio.c, which is where the other two
filesystems copied this code from.
sufficient to guarantee that this race is not hit. The XLOCK will likely
have to be redesigned due to the way reference counting and mutexes work
in FreeBSD. We currently can not be guaranteed that xlock was not set
and cleared while we were blocked on the interlock while waiting to check
for XLOCK. This would lead us to reference a vnode which was not the
vnode we requested.
- Add a backtrace() call inside of INVARIANTS in the hopes of finding out if
this condition is ever hit. It should not, since we should be retaining
a reference to the vnode in these cases. The reference would be sufficient
to block recycling.
This code dates back to the very first diskless support on FreeBSD,
back when swapon(8) couldn't simply be run on a NFS backed file.
Suggested replacement command sequence on the client:
dd if=/dev/zero of=/swapfile bs=1k count=1 oseek=100000
swapon /swapfile
rm -f /swapfile
For whatever value of 100000 you want.
1) avoid immediately calling bzero() after malloc() by passing M_ZERO
2) do not initialize individual members of the global context to zero
3) remove an unused assignment of ifctx in bootpc_init()
Reviewed by: tegge
to set np->n_size back to the desired size again after calling
nfs_meta_setsize(), since it could end up in nfs_loadattrcache() getting
called, which would change n_size back to the value it had before the
truncate request was issued. The result of this bug is that the size info
cached in the nfsnode becomes incorrect, lseek(fd, ofs, SEEK_END) seeks
past the end of the file, stat() returns the wrong size, etc.
PR: 41792
MFC after: 2 weeks
has not been cleaned in the meantime, since this can happen during
a forced unmount. Also add a comment that nfs_removeit() should
really be locking the directory vnode before calling nfs_removerpc().
Reported by: mbr
Tested by: mbr
MFC after: 1 week
nfs_lock.c. Right now, if we permit a signal to interrupt the sleep,
we will slip the lock and no process on that client, the server, or
any other client will be able to acquire the lock. This can happen,
for example, if a user hits Ctrl-C or Ctrl-T while a process is
waiting for the lock. By removing PCATCH, we prevent that from
happening, at the cost of not permitting a user-requested lock abort:
also nasty. However, a user interface bug might be preferable to a
serious semantic bug, so we go with that for now.
We need to teach the rpc.lockd/kernel protocol how to abort lock
requests, and rpc.lockd how to handle aborted lock requests; patches
for the kernel bit are floating around, but no rpc.lockd bit yet.
Approved by: re (scottl)
to avoid Bad Things(TM) happening (eg: df crashing with a floating point
exception).
Submitted by: Harold Gutch <logix@foobar.franken.de>
Approved by: re (scottl)
VOP_SETATTR() or VOP_GETATTR(); without these locks (a) VFS_DEBUG_LOCKS
will panic, and (b) it may be possible to corrupt entries in the cached
vnode attributes in the nfsnode, since nfsnode attribute cache data is
also protected by the vnode lock.
Approved by: re (jhb)
Pointed out by: VFS_DEBUG_LOCKS
- Move struct sigacts out of the u-area and malloc() it using the
M_SUBPROC malloc bucket.
- Add a small sigacts_*() API for managing sigacts structures: sigacts_alloc(),
sigacts_free(), sigacts_copy(), sigacts_share(), and sigacts_shared().
- Remove the p_sigignore, p_sigacts, and p_sigcatch macros.
- Add a mutex to struct sigacts that protects all the members of the struct.
- Add sigacts locking.
- Remove Giant from nosys(), kill(), killpg(), and kern_sigaction() now
that sigacts is locked.
- Several in-kernel functions such as psignal(), tdsignal(), trapsignal(),
and thread_stopped() are now MP safe.
Reviewed by: arch@
Approved by: re (rwatson)
uptime. Where necessary, convert it back to Unix time by adding boottime
to it. This fixes a potential problem in the accounting code, which would
compute the elapsed time incorrectly if the Unix time was stepped during
the lifetime of the process.
machines where the 'long' number of blocks in struct statfs wont fit.
Instead of chosing an artificial 512 byte block size, simply scale it up
until we avoid an overflow. NFSv3 reports the sizes in bytes, and the
blocksize is a figment of nfsclient's imagination.
Instead, use the generic vaccess() operation to determine whether
an operation is permitted. This avoids embedding knowledge on
vnode permission bits such as VAPPEND in the NFS client.
PR: kern/46515
vaccess() patch submitted by: "Peter Edwards" <pmedwards@eircom.net>
Approved by: tjr, roberto (mentor)
a follow on commit to kern_sig.c
- signotify() now operates on a thread since unmasked pending signals are
stored in the thread.
- PS_NEEDSIGCHK moves to TDF_NEEDSIGCHK.
opening the POSIX fifo; convert ENXIO error returns to EOPNOTSUPP.
This improves handling of the case where the /var/run/lock fifo exists
but there is no listener: we immediately return EOPNOTSUPP rather
than blocking until a listener turns up. This could occur during a
diskless boot before rpc.lockd is loaded, or if the lock file persists
across a reboot following the disabling of rpc.lockd. This may have
suddenly started to occur due to fifo blocking fixes--previously it
looks like attempts to read on a fifo with no listener would time out
due to insufficient resources.
Reviewed by: alfred
