Hi,

I want to trace the overall flow of mkfs inside linux kernel. Specifically want to know which kernel fs data structures are affected when we run "mkfs" ? What all "mkfs" command writes on the block device when we run the command? Are there any good documents which can explain the same?

There's nothing special about mkfs (mkfs.ext2, mkfs.msdos, mkfs.xfs, mkfs.btrfs, etc.) regarding the kernel.

From the kernel point of view, it's a userspace program that write to a block device, eg. you could use 'dd' to achieve the same result (using a filesystem image).

The kernel is using the "output" of mkfs later, when you issue "mount" command to mount the filesystem stored on the block device. Regards. -- Yann Droneaud OPTEYA

when u execute "mkfs", based on your "-t" filesystem passed in to mkfs, one of the following command line utility will be executed: mkfs.cramfs mkfs.ext4 mkfs.minix mkfs.reiserfs mkfs.bfs mkfs.ext2 mkfs.ext4dev mkfs.msdos mkfs.vfat mkfs.btrfs mkfs.ext3 mkfs.jfs mkfs.ntfs mkfs.xfs and for each of the above command line there is a fs utility that include it. Look into the source for good understanding. For ext2/ext3 fs, it is called e2fsprogs. So in Ubuntu (or Debian-based distro) u do a "apt-get source e2fsprogs" to get the source: reading the source of mkfs's main() function: http://pastebin.com/xcsB6GUC u can see that after lots of code on setting structures in memory, it start by writing the inode table etc: write_inode_tables(fs, lazy_itable_init, itable_zeroed); create_root_dir(fs); create_lost_and_found(fs); reserve_inodes(fs); create_bad_block_inode(fs, bb_list); Following through the source code is much more understandable than going through output of "strace", which records all the interface with the kernel. Follow through the following slide: http://www.geego.com/free-linux-lpic-training-material-study-guide/lpic1-mod... and forward a few slides and u will understand that mkfs is just making the header structures on the harddisk to contain the definition of the FS : Similarly u can find many university courses on filesystem internal, eg: http://scx010c06a.blogspot.sg/2012/03/second-extended-file-system-ext2.html Generally, real-life analysis of the harddisk/filesystem is done in forensic, so if u googling for fs forensics u can find lots of tools that walk the harddisk for the different components: http://www.dfrws.org/2007/proceedings/p55-barik.pdf http://www.cs.kau.se/~stefan/forensics/chapter14-15.pdf http://www.blackhat.com/presentations/bh-asia-03/bh-asia-03-grugq/bh-asia-03... http://www.dfrws.org/2007/proceedings/p55-barik_pres.pdf and this is forensics of ext4 filesystem: http://www.dfrws.org/2012/proceedings/DFRWS2012-13.pdf Understanding "mkfs", is really as good as understanding FS internals. On Fri, Jan 4, 2013 at 11:12 PM, KASHISH BHATIA < kashish.bhatia1989@gmail.com> wrote:

Hi,

I want to trace the overall flow of mkfs inside linux kernel. Specifically want to know which kernel fs data structures are affected when we run "mkfs" ? What all "mkfs" command writes on the block device when we run the command? Are there any good documents which can explain the same?

--

Regards, Kashish Bhatia

_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

-- Regards, Peter Teoh