MFC r348251:

Remove "struct ucred*" argument from vtruncbuf

vtruncbuf takes a "struct ucred*" argument. AFAICT, it's been unused ever
since that function was first added in r34611. Remove it. Also, remove some
"struct ucred" arguments from fuse and nfs functions that were only used by
vtruncbuf.

Reviewed by: cem
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D20377

Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

MFC r317273 (by cem):
fuse: Implement FOPEN_KEEP_CACHE flag

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix fuse so that stale buffer cache data isn't read.

When I/O on a file under fuse is switched from buffered to DIRECT_IO,
it was possible to read stale (before a recent modification) data from
the buffer cache. This patch invalidates the buffer cache for the
file to fix this.

PR: 194293
MFC after: 2 weeks

Fix white spaces.

Make fuse(4) respect FOPEN_DIRECT_IO. This is required for correct
operation of GlusterFS.

PR: 192701
Submitted by: harsha at harshavardhana.net
Reviewed by: kib@
MFC after: 1 month
Sponsored by: The FreeBSD Foundation

- Current caching mode is completely broken because it simply relies
on timing of the operations and not real lookup, bringing too many
false positives. Remove the whole mechanism. If it needs to be
implemented, next time it should really be done in the proper way.
- Fix VOP_GETATTR() in order to cope with userland bugs that would
change the type of file and not panic. Instead it gets the entry as
if it is not existing.

Reported and tested by: flo
MFC after: 2 months
X-MFC: 241519, 242536,242616

Rename s/DEBUG()/FS_DEBUG() and s/DEBUG2G()/FS_DEBUG2G() in order to
avoid a name clash in sparc64.

MFC after: 2 months
X-MFC: r241519

Import a FreeBSD port of the FUSE Linux module.
This has been developed during 2 summer of code mandates and being revived
by gnn recently.
The functionality in this commit mirrors entirely content of fusefs-kmod
port, which doesn't need to be installed anymore for -CURRENT setups.

In order to get some sparse technical notes, please refer to:
http://lists.freebsd.org/pipermail/freebsd-fs/2012-March/013876.html

or to the project branch:
svn://svn.freebsd.org/base/projects/fuse/

which also contains granular history of changes happened during port
refinements. This commit does not came from the branch reintegration
itself because it seems svn is not behaving properly for this functionaly
at the moment.

Partly Sponsored by: Google, Summer of Code program 2005, 2011
Originally submitted by: ilya, Csaba Henk <csaba-ml AT creo DOT hu >
In collabouration with: pho
Tested by: flo, gnn, Gustau Perez,
Kevin Oberman <rkoberman AT gmail DOT com>
MFC after: 2 months