freebsd-nq

History

Poul-Henning Kamp aec0fb7b40 Back when VOP_* was introduced, we did not have new-style struct

initializations but we did have lofty goals and big ideals.

Adjust to more contemporary circumstances and gain type checking.

	Replace the entire vop_t frobbing thing with properly typed
	structures.  The only casualty is that we can not add a new
	VOP_ method with a loadable module.  History has not given
	us reason to belive this would ever be feasible in the the
	first place.

	Eliminate in toto VOCALL(), vop_t, VNODEOP_SET() etc.

	Give coda correct prototypes and function definitions for
	all vop_()s.

	Generate a bit more data from the vnode_if.src file:  a
	struct vop_vector and protype typedefs for all vop methods.

	Add a new vop_bypass() and make vop_default be a pointer
	to another struct vop_vector.

	Remove a lot of vfs_init since vop_vector is ready to use
	from the compiler.

	Cast various vop_mumble() to void * with uppercase name,
	for instance VOP_PANIC, VOP_NULL etc.

	Implement VCALL() by making vdesc_offset the offsetof() the
	relevant function pointer in vop_vector.  This is disgusting
	but since the code is generated by a script comparatively
	safe.  The alternative for nullfs etc. would be much worse.

	Fix up all vnode method vectors to remove casts so they
	become typesafe.  (The bulk of this is generated by scripts)

2004-12-01 23:16:38 +00:00

ffs_alloc.c

Move UFS from DEVFS backing to GEOM backing.

2004-10-29 10:15:56 +00:00

ffs_balloc.c

Explicitly break out NETA license from Berkeley license to clearly

2004-10-20 08:05:02 +00:00

ffs_extern.h

Back when VOP_* was introduced, we did not have new-style struct

2004-12-01 23:16:38 +00:00

ffs_inode.c

Loose the v_dirty* and v_clean* alias macros.

2004-10-25 09:14:03 +00:00

ffs_rawread.c

Move UFS from DEVFS backing to GEOM backing.

2004-10-29 10:15:56 +00:00

ffs_snapshot.c

Move UFS from DEVFS backing to GEOM backing.

2004-10-29 10:15:56 +00:00

ffs_softdep_stub.c

Use __FBSDID().

2003-06-11 06:34:30 +00:00

ffs_softdep.c

Move UFS from DEVFS backing to GEOM backing.

2004-10-29 10:15:56 +00:00

ffs_subr.c

Update for the KDB debugger framework:

2004-07-10 20:45:47 +00:00

ffs_tables.c

Remove advertising clause from University of California Regent's

2004-04-07 03:47:21 +00:00

ffs_vfsops.c

Back when VOP_* was introduced, we did not have new-style struct

2004-12-01 23:16:38 +00:00

ffs_vnops.c

Back when VOP_* was introduced, we did not have new-style struct

2004-12-01 23:16:38 +00:00

fs.h

Fix fsbtodb() for UFS1. This fixes an overflow for file sizes >1 TB,

2004-10-09 20:16:06 +00:00

README.snapshot

Remove the comment about dump(8) not working properly with snapshots.

2002-12-12 00:31:45 +00:00

README.softupdates

…

softdep.h

…

README.softupdates

$FreeBSD$

Using Soft Updates

To enable the soft updates feature in your kernel, add option
SOFTUPDATES to your kernel configuration.

Once you are running a kernel with soft update support, you need to enable
it for whichever filesystems you wish to run with the soft update policy.
This is done with the -n option to tunefs(8) on the UNMOUNTED filesystems,
e.g. from single-user mode you'd do something like:

	tunefs -n enable /usr

To permanently enable soft updates on the /usr filesystem (or at least
until a corresponding ``tunefs -n disable'' is done).


Soft Updates Copyright Restrictions

As of June 2000 the restrictive copyright has been removed and 
replaced with a `Berkeley-style' copyright. The files implementing
soft updates now reside in the sys/ufs/ffs directory and are
compiled into the generic kernel by default.


Soft Updates Status

The soft updates code has been running in production on many
systems for the past two years generally quite successfully.
The two current sets of shortcomings are:

1) On filesystems that are chronically full, the two minute lag
   from the time a file is deleted until its free space shows up
   will result in premature filesystem full failures. This
   failure mode is most evident in small filesystems such as
   the root. For this reason, use of soft updates is not
   recommended on the root filesystem.

2) If your system routines runs parallel processes each of which
   remove many files, the kernel memory rate limiting code may
   not be able to slow removal operations to a level sustainable
   by the disk subsystem. The result is that the kernel runs out
   of memory and hangs.

Both of these problems are being addressed, but have not yet
been resolved. There are no other known problems at this time.


How Soft Updates Work

For more general information on soft updates, please see:
	http://www.mckusick.com/softdep/
	http://www.ece.cmu.edu/~ganger/papers/CSE-TR-254-95/

--
Marshall Kirk McKusick <mckusick@mckusick.com>
July 2000