simplefs - a ridiculosly simple file system from the scratch

[Rajat Sharma]

On Tue, Aug 6, 2013 at 8:36 PM, Sankar P <sankar.curiosity at gmail.com> wrote:
> On Tue, Aug 6, 2013 at 10:10 AM, Rajat Sharma <fs.rajat at gmail.com> wrote:
>> Hey buddy, its a good work. You never know how many people you end up
>> helping with this code. I would definitely recommend this as a
>> starter.
>>
>
> Thank you so much :) It feels so nice to hear this from you :)
>
>> One recommendation: add support for page-cache. Start with read-cache
>> only, and then mmap support, you need that to allow binary execution.
>>
>
> oh okay. You suggest that I should do this before I start implementing
> the support for extents ?
>

Its upto you, but doing that before extents seems more towards basic
tutorial steps for writing a filesystem.

> Sankar
>
>> -Rajat
>>
>> On Tue, Aug 6, 2013 at 12:27 AM, Sankar P <sankar.curiosity at gmail.com> wrote:
>>> 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 at kernelnewbies.org
>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
>
>
> --
> Sankar P
> http://psankar.blogspot.com