Noted by: Michael Butler <imb protected-networks.net>

cgit

Require both the prison mutex and allprison_lock when pr_ref or
pr_uref go to/from zero.  Adding a non-first or removing a non-last
reference remain lock-free.  This means that a shared hold on
allprison_lock is sufficient for prison_isalive() to be useful, which
removes a number of cases of lock/check/unlock on the prison mutex.

Expand the locking in kern_jail_set() to keep allprison_lock held
exclusive until the new prison is valid, thus making invalid prisons
invisible to any thread holding allprison_lock (except of course the
one creating or destroying the prison).  This renders prison_isvalid()
nearly redundant, now used only in asserts.

Differential Revision:	https://reviews.freebsd.org/D28419
Differential Revision:	https://reviews.freebsd.org/D28458

cgit

The data is only needed by filesystems that
1. use buffer cache
2. utilize clustering write support.

Requested by:	mjg
Reviewed by:	asomers (previous version), fsu (ext2 parts), mckusick
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D28679

cgit

Make sys/buf.h, sys/pipe.h, sys/fs/devfs/devfs*.h headers usable in
userspace, assuming that the consumer has an idea what it is for.
Unhide more material from sys/mount.h and sys/ufs/ufs/inode.h,
sys/ufs/ufs/ufsmount.h for consumption of userspace tools, with the
same caveat.

Remove unacceptable hack from usr.sbin/makefs which relied on sys/buf.h
being unusable in userspace, where it override struct buf with its own
definition.  Instead, provide struct m_buf and struct m_vnode and adapt
code to use local variants.

Reviewed by:	mckusick
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D28679

cgit

cgit

Avoids locking and unlocking the vnode.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D28695

cgit

This generalizes what vop_stdgetwritemount used to be doing.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D28695

cgit

Tested with glibc test suite.

The C variant in libkern performs excessive branching to find the zero
byte instead of using the bsfq instruction. The same code patched to use
it is still slower than the routine implemented here as the compiler
keeps neglecting to perform certain optimizations (like using leaq).

On top of that the routine can be used as a starting point for copyinstr
which operates on words intead of bytes.

The previous attempt had an instance of swapped operands to andq when
dealing with fully aligned case, which had a side effect of breaking the
code for certain corner cases. Noted by jrtc27.

Sample results:

$(perl -e "print 'A' x 3"):
stock:  211198039
patched:338626619
asm:    465609618

$(perl -e "print 'A' x 100"):
stock:   83151997
patched: 98285919
asm:    120719888

Reviewed by:	jhb, kib
Differential Revision:	https://reviews.freebsd.org/D28779

cgit