id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	field_blocks	field_dependson	field_seealso
60	ext4 filesystem driver	Martin Decky		"Implement a native HelenOS driver for the ext4 file system.

 Details::
 The new driver should be realized as a standalone server process which plugs itself into the HelenOS VFS framework and implements the VFS and libfs interfaces in the ext4 specific way.

 The implementation can proceed in several phases. In the first phase, read-only support for ext4 should be implemented. In the following phases, write features corresponding to specific compatibility levels (plain ext2, ext2 with large files, ext2 with hashed B-trees, ext2 with sparse superblocks, ext3 with journaling, ext4 with extends) can be incrementally added.

 What Gains and Benefits will this bring?::
 The only persistent file system supported by HelenOS so far has been FAT16. This file system has some inconvenient limitations such as the 8.3 file names and, which is more important, does not force VFS to provide interfaces for writing back the superblock. On the other hand, ext4 is a reasonably advanced file system commonly used on the Linux platform and its implementation will lead to adding needed abstractions to the VFS protocol. This will benefit future additions of other persistent file systems.

 Difficulty::
 medium (read-only ext4) to hard (full ext4 write support)

 Required skills::
 A successful applicant will have good skills of programming in the C language and also the ability to program in a multi-server environment, which includes communicating using HelenOS IPC.

 Documentation::
 The ext4 file system on-disk format is described in documents linked from the [wiki:DeveloperDocs#FileSystems file systems] section of our developer documentation page. The file system framework is described in the [wiki:FSDesign Implementation and design of the file system layer] knowledge article and HelenOS IPC is documented in the [wiki:IPC IPC for Dummies] knowledge article."	enhancement	new	minor		fs/other	mainline		fs, suggestion, gsoc	jakub@…