Hi, For learning purposes, I thought I would implement a filesystem from the scratch. It has reached a state where I can do a 1.0 release. The sources are at: https://github.com/psankar/simplefs The layout is simple. The first (zeroth) block is the superblock and contains information like fs magic, number of inodes, freeblock map etc. The next block is the inode store. Creation of files and directories is supported. Nested directories are supported. A file can grow up to one block only. The data blocks for a directory contain the filename and inode number of its children. For files, it will obviously contain the actual data of the file. There are three rudimentary locks to make sure the accesses are thread safe. The 1.0 version is filled with a lot of TODOs and memory leaks. Also while implementing this, I realized that it is a bad idea to maintain the superblock and the freeblock store together in a block. So I am planning to change the on-disk layout in the next version. Apart from moving the super block to minimize locks, I am planning to implement support for extents in the next version, and journalling in the next-to-next version. The next version will take some time to come, though. But if someone wants to try filesystems from the scratch, I thought it may be useful if I share the link now itself. Also, I take this moment to thank the kernelnewbies list, especially the regular people like Mulyadi Santosa, Valdis Kletnieks, Rajat Sharma, Greg Freemyer etc. Also I would like to thank Neha Naik, Manish Katiyar who helped me with some queries during this particular implementation. I saw that Manish Katiyar has also done a similar from-the-scratch implementation and it motivated me to pursue further. Any feedback on the code is welcome. Although, I want to inform that I plan to change the locking until after I decide on a good on-disk layout for the next version, which will by-design minimize the locking needs, by splitting out freestore from superblock, keep track of children inode in a better way etc. Also I have been resisting the urge to look at ext or any other filesystem's design so as to not skew my thoughts and go with a fresh state of mind and get my own design :) Thanks. -- Sankar P http://psankar.blogspot.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
