Looking for a simple file systems project to work on? Try one of the following. The contact is the IRC nick of someone on #linuxfs you can talk to to find out more about the project. If you can also be a contact for a project, please add yourself as one.
Lazy atime - Keep atime in memory, only update it on-disk when the inode will be written out for some other reason (basically, don't dirty the inode on an atime update). This is as opposed to plain old noatime - see touch_atime() in fs/inode.c. Contact: valh Update I wrote both a lazy atime and a relative atime, see: http://infohost.nmt.edu/~val/patches.html#relatime
cases. This was proposed to be a feature of the fstatat() system call, passing flags AT_GET_{SIZE,INO,UID,GID,...} to request only the specified fields, and ignoring others if any of those flags are given. Contact: valh, zab Update Trevor Woerner (tlw) is starting work on this.
SEEK_HOLE, SEEK_DATA - New parameters to seek() asking for the next part of the file with data in it. As it currently stands, even if a file is sparse on disk, the file system still has to shovel zeroes out through the read() system call. Some applications, such as archivers or backup programs, can make good use of an interface that says, e.g., the next 8MB of the file are all zeroes, instead of having to read 8MB of zeroes. See the following: http://blogs.sun.com/roller/page/bonwick?entry=seek_hole_and_seek_data http://www.google.com/search?hl=en&lr=&q=+site:lkml.org+seek_hole+seek_data Contact: cw, valh Update Eric Lorimer has written an initial implementation for ext3.
A generically useful library for finding and managing contiguous areas of disk space. Getting the interface right is non-trivial, but there are a lot of concepts which are independent of on-disk file system layout which could be reused. Good starting points are the ext3 reservation code and/or the XFS extent allocation code (the ext2 preallocation code is NOT a good place to start). Short of that, finish and test the port of the ext3 reservation code to ext2, started here: http://infohost.nmt.edu/~val/patches/resv_only_patch Contact: valh
Some kind of hook into the disk EIO reporting which allows file systems to register a handler which does things like set the "fsck me now" bit. Contact: valh
Simple block bitmap sanity checking for ext2/3/4. When a new block bitmap is read from disk in read_block_bitmap() there are a few bits that should ALWAYS be set for each group. In particular, the blocks given by desc->bg_block_bitmap, desc->bg_inode_bitmap, and bg_inode_table, +sbi->s_itb_per_group">desc->bg_inode_table, +sbi->s_itb_per_group. If any of those those bits (shifted to be relative to the current group, of course) are not set then the on-disk group descriptor is corrupt, or there is some problem reading it from disk and an ext3_error() should be called (possibly making the filesystem read-only).