Any way to output semantics of block

[Jun He <jhe@cs.wisc.edu>]

Hi all,

I use the output of blktrace as the input of my block device simulator.  Now I
want to add semantics of data stored in each block to the output, so
my simulator can use them.  For example, I would like to know if the block is
storing file data or file system metadata. If it is metadata, I'd like to know
what kind of metadata it is. For example, ext4's superblock, inode table,
blockbitmap, or extent tree block ... If it is file data, I'd like to know
its filename.

Output of blkparse may look like:

op block#  semantics
w  43      inode-table
w  88      directory-entries
r  48      file-data(/home/user1/data)
w  77      extent-tree-block
w  777     journal

Statically, I can get the semantics of, for example, ext4 by debugfs and
dumpe2fs. And this is fine for most of the cases since the format of ext4 is
mostly fixed (blocks that store inode table will always store inode table). But
the data semantics in a block does change over time in some case. For example, a
block can store file data at a time and extent tree block at another time.  So I
cannot use the statically collected semantics to feed my simulator.

Is outputting semantics already supported by blktrace?

If not, any suggestions for implementing it?

Thanks,
Jun