Hi, Thanks for the replies. But I should have been more clear when phrasing the question. In every filesystem implmentation there are two structrues the super_block structure and the super_block_info structure. The super_block_info structure will be in the union in the vfs_super_block and the super_block_info has the pointer to the actual super_block of the filesystem. For example in the vfs_super_block structure there is the msdos_sb_info. And the msdos_sb_info has a pointer to the fat_boot_sector structure. I noticed that the variables in the super_block_info are not uniform across filesystem implementations. From your replies I see that the super_block_info is implementation dependent and so it is the driver's implementor that decides which info he needs. Am I right? I am trying to implement a filesytem for the sake of learning and so am looking into all this. Thanks, VS --- Jan Hudec <bulb@ucw.cz> wrote: > On Mon, Sep 16, 2002 at 05:36:43AM +0100, Dharmender > Rai wrote: > > a super block is related to one file system. linux > > supports many. "x" super-blocks can be used to > support > > that "x" fs types. the info about the fs can be > > extracted using the union. > > More exactly, info the specific filesystem driver > uses internaly is > stored there. Noone but the driver system should > ever look there. > > > PS : union is being used to save space (also > because > > we need info abt 1 fs ) ;) > > > > --- VS <dojik@yahoo.com> wrote: > Hi, > > > > > > In the struct super_block in linux/fs.h > > > there is a union which has the union u which > points > > > to > > > the super_block_info of different file systems. > > > Could > > > someone tell me what this super_block_info is > and > > > what > > > it is used for. Is there any particular format > for > > > the > > > structure. Is there any documentation on this on > the > > > web. Also I think to add a filesystem I have to > use > > > the generic_spb pointer in this union. Any > pointers > > > are appreciated. > > It's data of filesystem driver. If you are writing a > driver, put > anything you need there. If not, don't ever thing of > looking there. > > If you are adding a driver, you may either patch > fs.h to include your > struct as well, or use the generic pointer. > > > > Thanks, > > > VS > > ------------------------------------------------------------------------------- > Jan 'Bulb' Hudec <bulb@ucw.cz> __________________________________________________ Do you Yahoo!? Yahoo! News - Today's headlines http://news.yahoo.com -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
