directories which aren't under the recipient's root.
Clean up of many error conditions involving descriptor passing, to
eliminate infinite loops, panics, premature garbage collection of
sockets, and descriptor leaks:
- Avoid letting unp_gc() see descriptors with a refcount of zero by
removing them from the socket's queue before releasing them.
- Avoid socket leak in PRU_ABORT (this will also gc descriptors queued
on a not-yet accepted socket when the accepting socket goes away).
- Put in block comment explaining how unp_gc() should work.
- Correctly manage unp_defer count so we don't get stuck in an infinite
loop with nothing to do.
- Don't tie MARK and DEFER bits so closely together.
- Mark descriptors queued on not-yet-accepted sockets as well.
- Don't call sorflush on non-socket, it doesn't work very well.
- Deal with discard of NULL file pointer.
- Hopefully cause GC to converge faster by only deferring sockets in
unp_mark().
limit into account when checking against the limit; fdp->fd_nfiles may
be greater than the current descriptor limit, and there may be space
in fdp->fd_ofiles beyond the limit. If we say it's available,
unp_externalize will get confused and panic when fdalloc fails.
deadlock in VOP_FSYNC() if the unreferenced vnode picked for
reclamation happened to be stacked on top of a vnode the process
already had locked. This could happen if the same filesystem was
accessed both through a union mount and directly; it seemed to happen
most frequently when the direct access was through NFS.
Avoid this deadlock by changing vinvalbuf to pass a new FSYNC_RECLAIM
flag bit to VOP_FSYNC() to indicate that a reclaim is in progress and
only a `shallow' fsync is necessary.
Do nothing in *_fsync() in umapfs, nullfs, and unionfs when
FSYNC_RECLAIM is set; the underlying vnodes will shortly be released
in *_reclaim and may be reclaimed (and fsync'ed) later.
was changes to comments only, but..)
Build vfs_getcwd.c as standard part of kernel.
Add implementation of fchroot(), since two emulations already had it.
Call vn_isunder() in fchdir(), chroot(), and fchroot() to make it harder
to escape chroot().
Add kernel implementation of getcwd() which uses this cache, falling
back to reading the filesystem on a cache miss.
Along for the ride: add new VOP_FSYNC flag FSYNC_RECLAIM indicating
that a reclaim is being done, so only a "shallow" fsync is needed.
