On Thu, Feb 21, 2008 at 09:39:20AM -0800, Mingming Cao wrote:
> On Tue, 2008-02-19 at 09:13 +0530, Aneesh Kumar K.V wrote:
> > We would like to get notified when we are doing a write on mmap section.
> > This is needed with respect to preallocated area. We split the preallocated
> > area into initialzed extent and uninitialzed extent in the call back. This
> > let us handle ENOSPC better. Otherwise we get ENOSPC in the writepage and
> > that would result in data loss. The changes are also needed to handle ENOSPC
> > when writing to an mmap section of files with holes.
> >
>
> Hi Aneesh,
>
> I have a concern, it seems we missed journalling the allocation activity
> for the mmaped write. See comments below...
>
> Another thing, perhaps similar patch should be ported to ext2/3, as this
> also addressed the mmaped write ENOSPC error without
> preallocation/deleyed allocation.
>
> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
......
> > +
> > +int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
> > +{
> > + return block_page_mkwrite(vma, page, ext4_get_block);
> > +}
> > +
>
> I don't see block allocation being journalled here. block_page_mkwrite()
> eventually calling block_prepare_write() which invokes ext4_get_block()
> without starting a new journal handle.
>
> Perhaps call ext4 write_begin() and write_end() inode operations, that
> would taking care of different write_begin and write_end for three
> different journalling mode.
>
You are correct. I missed the journalling details when working on the
patch. Will send the one with fix.
-aneesh
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