page 8
segment usage bitmaps. 1 bit for each block
block = 1024 bytes
1024 blocks per segment
segment block
-------------
0: header: - sb
- offset of usage changes
- num of usages
- offset of inode mapping changes
- num of inode changes
1: every 8th segment gets SB
256 bits: 1 byte
1024 bits: 4 bytes: int
NEED to store info in addressable buffers. CHECK kernel source.
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can I *remove* a buffer from cache, change data, then re-insert it?
Yes->
remove_from_queues(bh)
insert_into_queues(bh)
refile_buffer(bh)