On Mon 11-01-16 09:05:20, HUANG Weller (CM/ESW12-CN) wrote: > > > -----Original Message----- > > From: HUANG Weller (CM/ESW12-CN) > > Sent: Friday, January 08, 2016 8:47 AM > > To: 'Jan Kara' <jack@xxxxxxx> > > Cc: linux-ext4@xxxxxxxxxxxxxxx; Li, Michael <huayil@xxxxxxxxxxxxxxxx> > > Subject: RE: ext4 out of order when use cfq scheduler > > > > > > > > > > > > > > > > OK, so I was looking into the code and indeed, reality is correct > > > > > and my mental model was wrong! ;) I thought that inode gets added > > > > > to the list of inodes for which we need to wait for data IO > > > > > completion during transaction commit during block allocation. And I was > > wrong. > > > > > It used to happen in > > > > > mpage_da_map_and_submit() until commit f3b59291a69d (ext4: remove > > > > > calls to > > > > > ext4_jbd2_file_inode() from delalloc write path) where it got > > > > > removed. And that was wrong because although we submit data writes > > > > > before dropping handle for allocating transaction and updating > > > > > i_size, nobody guarantees that data IO is not delayed in the block > > > > > layer until > > > transaction commit. > > > > > Which seems to happen in your case. I'll send a fix. Thanks for > > > > > your report and persistence! > > > > > > > > > > > > > Thanks a lot for your feedback :-) > > > > Because I am not familiar with the detail of the ext4 internal code. > > > > I will try to > > > understand your explanation which you describe above. And have a look > > > on related funcations. > > > > Could you send the fix in this mail ? > > > > And whether the kernel 3.14 also have such issue, right ? > > > > > > The problem is in all kernels starting with 3.8. Attached is a patch > > > which should fix the issue. Can you test whether it fixes the problem for you? > > > > > > Honza > > > -- > > > > Yes, of course I will redo the test with the patch. And also give you feedback. > > Test result: > Test on 2 targets with the kernel applied your patch. Both of them are OK > after 5000 power failure tests. Our target test cycle is 10,000. By the > way, since your original patch can't be applied on 3.x kernel, The > attached one is based on yours and can applied on old kernel(mine is > 3.10) directly. Thanks for testing and the port! Once the patch is merged upstream, I'll backport it and push it to all active stable kernels. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
