E2compr 0.4 User Manual – e2compress work

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e2compress will require a lot of work. It’s not available undere2compr-0.4 at all yet.

Hopefully I will do these changes myself. e2compress is a bigprogram.

  • Put the verification and correction code into a library, so that it canbe shared by e2fsck.
  • Make e2compress refuse to work (or call the kernel code) forfiles that are open by other processes. (Of particular importance ispreventing writes from other processes from being lost.)One way of doing this –the way that the code in progress has beenusing– is to use the EXT2_NOCOMPR_FL bit, which can only beraised if no other processes have the file open, and which, whileraised, prevents other processes from opening it.Another way is to use mandatory file locking (flock() etc.).
  • Have e2compress able to compress or decompress “in place”,thus reducing problems of multiple links and processes wishing to writeto the file.
  • Better safety checks. Don’t just decompress in memory, but read thefile as written (thus catching some I/O errors) and warn if theuncompressed data could pass for data of a compressed cluster.

This work was in progress, but, for the 0.3.5 release, I decided just tofix one or two problems in an earlier version of e2compressrather than wait until the more featureful e2compress was ready.

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