Re: deadlocks caused by ext3/reiser dirty_inode calls during do_mmap_pgoff

[Chris Mason <mason@suse.com>]

On Tue, 2004-06-22 at 15:05, Andrew Morton wrote:
> Chris Mason <mason@suse.com> wrote:

> > Oh, just realized this will break our data=ordered setup.  prepare_write
> > is going to do things like allocating blocks in the file etc etc.  If we
> > close the transaction via commit_write(0 size) and crash, we'll leak.
> 
> OK, then just zero the pagecache page between `from' and `to' and call
> ->commit_write() with unmodified `from' and `to'?
> 
> > We might need to do prefault + pin on the user pages.
> 
> That's always been the correct way to fix these problems, but it involves a
> pagetable walk, which requires page_table_lock.  Not a popular thing to be
> doing on the write() fastpath.

Fair enough, zeroing between from and to should do it.

-chris