On 2010-06-18 20:14, Jens Axboe wrote: > On 2010-06-18 20:04, Eric Sandeen wrote: >> Jens Axboe wrote: >>> On 2010-06-18 17:28, Eric Sandeen wrote: >>>> Jens Axboe wrote: >>>>> On 18/06/10 16.59, Eric Sandeen wrote: >>>>> >>>>>> Eric Sandeen wrote: >>>>>> >>>>>>> Jens Axboe wrote: >>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> I was writing a small fio job file to do writes and read verifies on a >>>>>>>> device. It forks 32 processes, each writing randomly to 4 files with a >>>>>>>> block size between 4k and 16k. When it has written 1024 of those blocks, >>>>>>>> it'll verify the oldest 512 of them. Each block is checksummed for every >>>>>>>> 512b. It uses libaio and O_DIRECT. >>>>>>>> >>>>>>>> It works on ext2 and btrfs. I haven't run it to completion yet, but they >>>>>>>> survive 15-20 minutes just fine. ext4 doesn't even go a full minutes >>>>>>>> before this triggers: >>>>>>>> >>>>>>> Jens, can you try XFS too? Since ext3 can't do direct IO to a hole, >>>>>>> (and I'm not sure about btrfs in that regard), ext4 may be most similar >>>>>>> to xfs's behavior on the test ... wondering how it fares. >>>>>>> >>>>>>> Thanks, >>>>>>> -Eric >>>>>>> >>>>>> Actually mingming had a patch for direct-io.c which may be related, I'll >>>>>> test that out. >>>>>> >>>>> OK, I'll try XFS tonight as well. >>>>> >>>>> >>>>> >>>> I haven't been able to reproduce it on ext4 here, yet. >>>> >>>> FWIW here's the patch from mingming: >>>> >>>> When unaligned DIO writes, skip zero out the block if the buffer is marked >>>> unwritten. That means there is an asynconous direct IO (append or fill the hole) >>>> still pending. >>>> >>>> Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx> >>>> --- >>>> fs/direct-io.c | 3 ++- >>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>> >>>> Index: linux-git/fs/direct-io.c >>>> =================================================================== >>>> --- linux-git.orig/fs/direct-io.c 2010-05-07 15:42:22.855033403 -0700 >>>> +++ linux-git/fs/direct-io.c 2010-05-07 15:44:17.695007770 -0700 >>>> @@ -740,7 +740,8 @@ >>>> struct page *page; >>>> >>>> dio->start_zero_done = 1; >>>> - if (!dio->blkfactor || !buffer_new(&dio->map_bh)) >>>> + if (!dio->blkfactor || !buffer_new(&dio->map_bh) >>>> + || buffer_unwritten(&dio->map_bh)) >>>> return; >>>> >>>> dio_blocks_per_fs_block = 1 << dio->blkfactor; >>>> >>>> >>> >>> What is this patch against? >>> >> >> Applied to 2.6.32, seems to apply upstream as well. >> >> It hits dio_zero-block() > > Irk indeed, I am blind. The patch does not fix it. So just to confirm that this isn't a new regression, 2.6.34 fails in the same way. If I change the test to make the random writes overwrite existing blocks instead of filling holes, then there are no problems either. -- Jens Axboe -- 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
