Kernels and tools understand both v1 and v2 filesystems; newfs_lfs
generates v2 by default. Changes for the v2 layout include:
- Segments of non-PO2 size and arbitrary block offset, so these can be
matched to convenient physical characteristics of the partition (e.g.,
stripe or track size and offset).
- Address by fragment instead of by disk sector, paving the way for
non-512-byte-sector devices. In theory fragments can be as large
as you like, though in reality they must be smaller than MAXBSIZE in size.
- Use serial number and filesystem identifier to ensure that roll-forward
doesn't get old data and think it's new. Roll-forward is enabled for
v2 filesystems, though not for v1 filesystems by default.
- The inode free list is now a tailq, paving the way for undelete (undelete
is not yet implemented, but can be without further non-backwards-compatible
changes to disk structures).
- Inode atime information is kept in the Ifile, instead of on the inode;
that is, the inode is never written *just* because atime was changed.
Because of this the inodes remain near the file data on the disk, rather
than wandering all over as the disk is read repeatedly. This speeds up
repeated reads by a small but noticeable amount.
Other changes of note include:
- The ifile written by newfs_lfs can now be of arbitrary length, it is no
longer restricted to a single indirect block.
- Fixed an old bug where ctime was changed every time a vnode was created.
I need to look more closely to make sure that the times are only updated
during write(2) and friends, not after-the-fact during a segment write,
and certainly not by the cleaner.
- keep the case consistent between the actual name and what's referenced.
e.g, if it's `foo', don't use '.Nm Foo' at the start of a sentence.
- remove unnecessary `.Nm foo' after the first occurrence (except for
using `.Nm ""' if there's stuff following, or for the 2nd and so on
occurrences in a SYNOPSIS
- use Sx, Ic, Li, Em, Sq, and Xr as appropriate
Add flags "-b" and "-I" to dumplfs, to allow the user to specify the
location of the superblock and Ifile inode, respectively.
Don't print "corrupt segment header" any more for leftover slivers of
space too close to the next segment to write a partial-segment. In the
event that there was no such sliver, the segment still ends; recognize
this and print out the segment number, and superblock if asked.
Document all the flags in the man page.
Print the partial-segment write flags (SS_DIROP, SS_CONT).
Make the "-a" flag output look slightly better.
Change all hex numbers to lowercase, instead of having some upper and
some lower.
lukem