Hi Sankar, Have you written any code further. I read your file system's code and learnt a lot from it.
On Thu, Aug 8, 2013 at 8:36 PM, Sankar P <sankar.curios...@gmail.com> wrote: > okay. Thanks. I will update this list once I write enough code for the > next release :) > > On Thu, Aug 8, 2013 at 4:59 PM, Greg Freemyer <greg.freem...@gmail.com> > wrote: > > > > > > Sankar P <sankar.curios...@gmail.com> wrote: > >>On Thu, Aug 8, 2013 at 3:55 AM, Greg Freemyer <greg.freem...@gmail.com> > >>wrote: > > <snip> > >>> > >>> I just read your todo's. > >>> > >>> Multi-block files should come before extents and/or mmap support. I > >>> guess you realize that ext2 and ext3 are NOT extent based > >>filesystems. > >>> ext4 is the first extent based one. > >>> > >>> So its: > >>> ext2 - block based filesystem > >>> ext3 - block based with a journal > >>> ext4 - extent based with a journal > >>> > >>> In reality the current ext4 driver has a matrix of supported > >>features. > >>> There are flag bits which tell you which features a specific > >>> filesystem instance supports. You may want to atleast look at those > >>> feature flags to get an idea of the kinds of features ext4 supports. > >>> > >>> If you don't have lseek() support for read, you need to get it added. > >>> lseek() is pretty trivial for reads so there is not much reason not > >>to > >>> have it as the very next step. > >>> > >>> For write, it means you have to implement a read/modify/write cycle > >>in > >>> your filesystem. I gather you don't have that. > >>> > >>> With just those todo's I go in this order: > >>> > >>> - lseek() support with read (trivial) > >>> - partial block write support (requires read/modify/write logic, so > >>not trivial) > >>> - lseek() support for write (trivial now you have partial block write > >>support) > >>> - multi-block support, requires a major refactor most likely. > >>> > >> > >>Thank you so much for the detailed response. > >> > >>I will go in this order as this seem to be logically progressive nicely > >>iiuc. > >> > >>When do you think I should bring in support for mmap and page-caching > >>that Rajat in the above plan ? > >> > >>Thanks. > > > > I've never done a FS from scratch so I'm not sure, but I would delay > them as long as you can. > > > > I suspect you will need cache support to properly handle writes on a > multi block file, so as you work on that feature you may decide "now is the > time" for the cache. > > > > Mmap should be last. > > > > Greg > > -- > > Sent from my Android phone with K-9 Mail. Please excuse my brevity. > > > > -- > Sankar P > http://psankar.blogspot.com > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@kernelnewbies.org > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > -- Regards, Rishi Agrawal
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