On Thu, Feb 08, 2007 at 08:11:00AM -0500, Chris Mason wrote: > On Thu, Feb 08, 2007 at 09:50:13AM +1100, David Chinner wrote: > > > You don't need to lock out all truncation, but you do need to lock > > > out truncation of the page in question. Instead of your i_size > > > checks, check page->mapping isn't NULL after the lock_page? > > > > Yes, that can be done, but we still need to know if part of > > the page is beyond EOF for when we call block_commit_write() > > and mark buffers dirty. Hence we need to check the inode size. > > > > I guess if we block the truncate with the page lock, then the > > inode size is not going to change until we unlock the page. > > If the inode size has already been changed but the page not yet > > removed from the mapping we'll be beyond EOF. > > > > So it seems to me that we can get away with not using the i_mutex > > in the generic code here. > > vmtruncate changes the inode size before waiting on any pages. So, > i_size could change any time during page_mkwrite. Which would put us beyond EOF. Ok. > It would be a good idea to read i_size once and put it in a local var > instead. Will do - I'll snap it once the page is locked.... Thanks Chris. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
