Traditionally, fsck is invoked before the filesystems are mounted
and all checks are done to completion at that time. If background
checking is available, fsck is invoked twice. It is first invoked
at the traditional time, before the filesystems are mounted, with
the -F flag to do checking on all the filesystems that cannot do
background checking. It is then invoked a second time, after the
system has completed going multiuser, with the -B flag to do checking
on all the filesystems that can do background checking. Unlike
the foreground checking, the background checking is started
asynchonously so that other system activity can proceed even on
the filesystems that are being checked.
At the moment, only the fast filesystem supports background checking.
To be able to do background checking, a filesystem must have been
running with soft updates, not have been marked as needing a
foreground check, and be mounted and writable when the background
check is to be done (i.e., not listed as `noauto' in /etc/fstab).
These changes are the final piece needed to support background
filesystem checking. They will not have any effect until you update
your /etc/rc to invoke fsck in its new mode of operation. I am
still playing around with exactly what those changes should be
and should be committing them later this week.
Consider this /etc/fstab:
# Device Mountpoint FStype Options Dump Pass#
/dev/ad1s1b none swap sw 0 0
/dev/ad0s1b none swap sw 0 0
/dev/ad0s1a / ufs rw 1 1
/dev/ad0s1e /home ufs rw 2 2
/dev/ad1s1e /tmp ufs rw 2 2
/dev/ad1s1f /usr ufs rw 2 2
/dev/ccd0c /syv ufs rw 2 11
proc /proc procfs rw 0 0
ccd0c is striped over /dev/ad0f and /dev/ad1g
Without this pass, fsck in preen mode will check ad0s1a first,
and then issue three processes in parallel:
One process doing ad0s1e
One process doing ad1s1e and ad1s1f
One process doing ccd0c
There is no way to tell it that ccd0c overlaps ad0 and ad1.
With the patch, it will do it this way:
pass 2:
One process doing ad0s1e
One process doing ad1s1e and ad1s1f
and when they are complete:
pass 11:
One process doing ccd0c
This is much faster and more sane.
Valid pass numbers are anything from 1 to INTMAX-1.
I retired the '-l' option which tried to allow people to do
something like this, but which didn't work and which complicated
the code an awful lot.
Approved by: rwatson
Obtained from: NetBSD source tree
Second part of the fsck wrappers commit. This commit enables the new fsck
code (removing the fsck/* code and replacing it with the netbsd fsck
wrapper code), and enabling some FFS-based utilities to compile.
Details:
* quotacheck, fsdb required modification to use the fsck_ffs/ code rather
than fsck/ . This might change later since quotacheck requires preen.c
which should exist in fsck/ rather than fsck_ffs/
* src/Makefile has fsck_ffs added to it so it it built as part of the tree
now
* share/doc/smm/03.fsck/ uses the SMM.doc/ stuff from fsck_ffs, not fsck.
I've tested this, and it shouldn't require any changes on your machine.
The fsck wrapper reads /etc/fsck and is command-line-compatible enough
to not require rc changes (well, most changes unless you want to do
anything nifty by specifying the fs types explicityly, read the man page
if you want further details on what it can do.)
This now allows us to support multiple filesystem types during bootup.
