vvsfs_unlink was added to remove files. This part was done in the lab, but, in order to be comaptible with the additional function which is to remove the bounds of the file size and name sizes, some modifications were done in this part.
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Tracing through the ftruncate system call. A inode operation set_attr is called. Therefore, to implement this truncate, we need to add this operation into our file_inode_operations. In vvsfs_setattr, if the targeted size is smaller than the current one, it just simply changes the size of the file, while if the targeted size is larger, it will change the following bytes to 0. After doing this, now you are able to change the file size in this filesystem by using truncate command.
e.g.
truncate -s 10 file1
truncate -s 100 file1
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Two routines, vvsfs_mkdir and vvsfs_rmdir, were implemented, mkdir and rmdir commands now be executed to create a directory and remove a directory.
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Extra routines were added into vvsfs_inode and some modifications were done in vvsfs_create and vvsfs_readdir so it is able to record information including uid, gid and permissions.
Now you are able to see the users even after you remount the filesystem.
The files are now stored like a linked list, so you are able to create a file with a long name and larger size now, the inodes are connected to store larger files.
The data is now encrypted before storing into raw file and is decrypted before the file is opened to read. This restricts users who don't have this particular file system to access and view the contents of all the files.
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