On Thu, Feb 10, 2005 at 09:39:05AM -0800, Badari Pulavarty wrote: > On Wed, 2005-02-09 at 08:37, Stephen C. Tweedie wrote: > > Hi, > > > > On Wed, 2005-02-09 at 16:18, Badari Pulavarty wrote: > > > > > I am trying to understand journaling code in ext3. > > > Can some one enlighten me, why we need journal start > > > and stop in ext3_writeback_writepage() ? The block > > > allocation is already made in prepare_write(). > > > > prepare_write()/commit_write() are used for write(2) writes: the data is > > dirtied, but not immediately queued for IO (unless you're using O_SYNC). > > > > writepage is used when you want to write the page's data to disk > > *immediately* --- it's used when the VM is swapping out an mmaped file, > > or for msync(). > > > > So when writepage comes in, there's no guarantee that we've had a > > previous prepare. You can, for example, use ftruncate() to create a > > large hole in a file, and then mmap() it; if you then dirty a page, then > > the allocation occurs in the writepage(). So a transaction handle is > > necessary. > > > > --Stephen > > Okay, I started hacking. I added ext3_writeback_writepages() which calls > journal start/stop before calling mpage_writepages(). > > I am getting OOPs which puzzles me. 2 reasons why.. > > 1) First of all OOps in is __mod_timer() which I have not touched.
Total Guess: Callback after io-completed is blowing up ? Especially if it is trying to touch a buffer_head that isn't there or something. Sonny - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
