On Wed, Jun 17, 2009 at 02:05:20PM +0200, Jan Kara wrote: > On Wed 17-06-09 12:35:43, Nick Piggin wrote: > > On Mon, Jun 15, 2009 at 07:59:54PM +0200, Jan Kara wrote: > > > When we do delayed allocation of some buffer, we want to signal to VFS that > > > the buffer is new (set buffer_new) so that it properly zeros out everything. > > > But we don't have the buffer mapped yet so we cannot really unmap underlying > > > metadata in this state. Make VFS avoid doing unmapping of metadata when the > > > buffer is not yet mapped. > > > > Is this a seperate bugfix for delalloc filesystems? What is the error > > case of attempting to unmap underlying metadata of non mapped buffer? > > Won't translate to a serious bug will it? > If you do unmap_underlying_metadata on !mapped buffer, the kernel will > oops because it will try to dereference bh->b_bdev which is NULL. Ext4 or > XFS workaround this issue by setting b_bdev to the real device and b_blocknr > to ~0 so unmap_underlying_metadata does not oops. As I didn't want to do > the same hack in ext3, I need this patch... OK, just trying to understand the patchset. It would be nice to merge this ASAP as well and remove the ext4 and xfs hacks. > You're right it's not directly connected with the mkwrite problem and > can go in separately. Given how late it is, I'd like to get patch number 2 > reviewed (generic mkwrite changes), so that it can go together with patch > number 4 (ext4 fixes) in the current merge window. The rest is not that > urgent since it's not oopsable and you can hit it only when running out > of space (or hitting quota limit)... Sorry I was so late with looking at it. I am reading it now though (especially #2) ;) -- 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
