Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

udf_readatoffset: read through directory vnode, do not read > MAXBSIZE

Currently bread()-ing through device vnode with
(1) VMIO enabled,
(2) bo_bsize != DEV_BSIZE
(3) more than 1 block
results in data being incorrectly cached.
So instead a more common approach of using a vnode belonging to fs is now
employed.
Also, prevent attempt to bread more than MAXBSIZE bytes because of
adjustments made to account for offset that doesn't start on block
boundary.
Add expanded comments to explain the calculations.
Also drop unused inline function while here.

PR: kern/120967
PR: kern/129084

Reviewed by: scottl, kib
Approved by: jhb (mentor)

Add support for fifos to UDF:
- Add a separate set of vnode operations that inherits from the fifo ops
and use it for fifo nodes.
- Add a VOP_SETATTR() method that allows setting the size (by silently
ignoring the requests) of fifos. This is to allow O_TRUNC opens of
fifo devices (e.g. I/O redirection in shells using ">").
- Add a VOP_PRINT() handler while I'm here.

Move vnode-to-file-handle translation from vfs_vptofh to vop_vptofh method.
This way we may support multiple structures in v_data vnode field within
one file system without using black magic.

Vnode-to-file-handle should be VOP in the first place, but was made VFS
operation to keep interface as compatible as possible with SUN's VFS.
BTW. Now Solaris also implements vnode-to-file-handle as VOP operation.

VFS_VPTOFH() was left for API backward compatibility, but is marked for
removal before 8.0-RELEASE.

Approved by: mckusick
Discussed with: many (on IRC)
Tested with: ufs, msdosfs, cd9660, nullfs and zfs

Remove inode fields previously used for private inode hash tables.

Don't hold a reference to the disk vnode for each inode.

Eliminate cdev and vnode pointer to the disk from the inodes,
the mount holds everything we need.

Use vfs_hash instead of home-rolled.

Correct locking around g_vfs_close()

Remove basically unused root_vp pointer in udfmount.

MFC after: 1 week
Discussed with: scottl

Move UDF to GEOM backing instead of DEVFS.

For details, please see src/sys/ufs/ffs/ffs_vfsops.c 1.250.

First half of making UDF be endian-clean. This addresses the vfsops side.

Do the dreaded s/dev_t/struct cdev */
Bump __FreeBSD_version accordingly.

Add hooks for translating directories entries using the iconv methods.

Submitted by: imura@ryu16.org

Add a missing __inline. Strange that gcc never complained about it.
Implement udf_readlblks() in terms of RDSECTOR.

Implement the node cache as a hash table.

Factor out some ugle code that's shared by udf_readdir and udf_lookup.
Significantly de-obfuscate udf_lookup

Inspired By: tes@sgi.com

Sync with UDF p4 tree: Use POSIX integer types instead of BSD types.

Actually add the UDF files!