Matthew Dillon 2a31267e43 This is a major fixup of unionfs. At least 30 serious bugs have been ... fixed (many due to changing semantics in other parts of the kernel and not the original author's fault), including one critical one: unionfs could cause UFS corruption in the fronting store due to calling VOP_OPEN for writing without turning on vmio for the UFS vnode. Most of the bugs were related to semantics changes in VOP calls, lock ordering problems (causing deadlocks), improper handling of a read-only backing store (such as an NFS mount), improper referencing and locking of vnodes, not using real struct locks for vnode locking, not using recursive locks when accessing the fronting store, and things like that. New functionality has been added: unionfs now has mmap() support, but only partially tested, and rename has been enhanced considerably. There are still some things that unionfs cannot do. You cannot rename a directory without confusing unionfs, and there are issues with softlinks, hardlinks, and special files. unionfs mostly doesn't understand them (and never did). There are probably still panic situations, but hopefully no where near as many as before this commit. The unionfs in this commit has been tested overlayed on /usr/src (backing /usr/src being a read-only NFS mount, fronting /usr/src being a local filesystem). kernel builds have been tested, buildworld is undergoing testing. More testing is necessary.		1999-09-26 20:52:41 +00:00
..
cd9660	More removals of vnode->v_lastr, replaced by preexisting seqcount	1999-09-20 23:27:58 +00:00
coda	Remove five now unused fields from struct cdevsw. They should never	1999-09-25 18:24:47 +00:00
deadfs	$Id$ -> $FreeBSD$	1999-08-28 01:08:13 +00:00
fdescfs	Seperate the export check in VFS_FHTOVP, exports are now checked via	1999-09-11 00:46:08 +00:00
fifofs	$Id$ -> $FreeBSD$	1999-08-28 01:08:13 +00:00
msdosfs	More removals of vnode->v_lastr, replaced by preexisting seqcount	1999-09-20 23:27:58 +00:00
ntfs	Seperate the export check in VFS_FHTOVP, exports are now checked via	1999-09-11 00:46:08 +00:00
nullfs	Seperate the export check in VFS_FHTOVP, exports are now checked via	1999-09-11 00:46:08 +00:00
portalfs	Seperate the export check in VFS_FHTOVP, exports are now checked via	1999-09-11 00:46:08 +00:00
procfs	Seperate the export check in VFS_FHTOVP, exports are now checked via	1999-09-11 00:46:08 +00:00
specfs	Remove a warning check which was too general.	1999-09-25 18:52:03 +00:00
umapfs	Seperate the export check in VFS_FHTOVP, exports are now checked via	1999-09-11 00:46:08 +00:00
unionfs	This is a major fixup of unionfs. At least 30 serious bugs have been	1999-09-26 20:52:41 +00:00