freebsd-skq/sys/ufs
Kirk McKusick aa7ddc85c7 When a file is first being written, the dynamic block reallocation
(implemented by ffs_reallocblks_ufs[12]) relocates the file's blocks
so as to cluster them together into a contiguous set of blocks on
the disk.

When the cluster crosses the boundary into the first indirect block,
the first indirect block is initially allocated in a position
immediately following the last direct block.  Block reallocation
would usually destroy locality by moving the indirect block out of
the way to keep the data blocks contiguous.  This change compensates
for this problem by noting that the first indirect block should be
left immediately following the last direct block.  It then tries
to start a new cluster of contiguous blocks (referenced by the
indirect block) immediately following the indirect block.

We should also do this for other indirect block boundaries, but it
is only important for the first one.

Suggested by: Bruce Evans
MFC:          2 weeks
2012-11-03 18:55:55 +00:00
..
ffs When a file is first being written, the dynamic block reallocation 2012-11-03 18:55:55 +00:00
ufs The r241025 fixed the case when a binary, executed from nullfs mount, 2012-11-02 13:56:36 +00:00