a potential problem with cleaning fragments at all.
Better sanity checks when selecting files to coalesce; in particular don't
shift too far left when comparing the number of discontinuities to the log2
of the number of total blocks.
Better log messages: note beginning of coalescing correctly; also take
the log message from add_segment out of "if (debug)" for symmetry with the
"finished segment" message.
Use lfs_bmapv to find the inode, rather than looking it up manually in
the ifile; this should give more up-to-date information, since trolling
through every inode in the fs could take some time.
be digging itself deeper into a hole, it forks off a subprocess
that locates files with too many discontinuities and rewrites them, if
there is enough room.
Optionally the user can manually coaleasce files by running with "-c".
The recent change to lfs_markv is required for the coalescer to do anything.
All of "digging itself deeper", "too many discontinuities", and "enough room"
need to be better defined.
because of the disklabel.
Fix a problem with inode block handling that sometimes caused the wrong
blocks to be read, causing either cleaning failures or panics with v2 file
systems.
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.
