On Tue, Sep 01 2009, Theodore Tso wrote: > On Mon, Aug 31, 2009 at 09:41:26PM +0200, Jens Axboe wrote: > > > > Here's the 15th version of the writeback patches. > > The test-bdi branch of ext4.git tree is a combination of the patches I > plan to push once the merge window opens, plus v15 per-bdi patches. > On the ext4 call I've recruited some ext4 developers to do some > testing and benchmarking *before* the merge window opens. Great, thanks a lot for that! > I've found something potentially wrong with the writeback. It was > careful to sync the disk before shutting down the system, and I got > the following error. > > [ 660.499155] ext4_da_writepages: jbd2_start: 32768 pages, ino 41; err -30 > [ 660.505664] Pid: 1848, comm: flush-8:0 Not tainted 2.6.31-rc8-01474-geef6bd0 #362 > [ 660.512402] Call Trace: > [ 660.514982] [<c064412f>] ? printk+0x14/0x16 > [ 660.518851] [<c023ac4a>] ext4_da_writepages+0x213/0x40e > [ 660.523356] [<c023aa37>] ? ext4_da_writepages+0x0/0x40e > [ 660.528383] [<c01b65a8>] do_writepages+0x28/0x39 > [ 660.533534] [<c01f1e07>] writeback_single_inode+0x15c/0x346 > [ 660.538401] [<c0165b23>] ? down_read_trylock+0x3e/0x48 > [ 660.542921] [<c01f2892>] generic_sync_wb_inodes+0x2ab/0x37b > [ 660.547805] [<c01f2a2a>] wb_writeback+0xc8/0xfa > [ 660.551975] [<c01f2abb>] wb_do_writeback+0x5f/0x118 > [ 660.556333] [<c01f2b95>] bdi_writeback_task+0x21/0x92 > [ 660.560838] [<c01c0f5d>] bdi_start_fn+0x63/0xb2 > [ 660.565647] [<c01c0efa>] ? bdi_start_fn+0x0/0xb2 > [ 660.569710] [<c0162363>] kthread+0x73/0x78 > [ 660.573528] [<c01622f0>] ? kthread+0x0/0x78 > [ 660.577355] [<c011e6f3>] kernel_thread_helper+0x7/0x10 > > ... and a very similar failure for inode 354 > > [ 660.582215] ext4_da_writepages: jbd2_start: 32768 pages, ino 354; err -30 > > Inode 41 is /var/lib/urandom/random-seed, and inode 354 is > /var/run/syslogd.pid. > > The failure occurs if I build w/o the ext4 "next" patches, and the > failure does not happen if I take build v2.6.31-rc8 without per-bdi > patches (with or without the ext4 patches). At a guess it looks like > the bdi threads are trying to write out the dirty files that were > written in the shutdown scripts, *after* the file system has been made > read-only in preparation for unmounting the file system in question. OK, that's definitely something that I will look into today. It isn't necessarily a writeback bug, but it does rather smell like it. -- Jens Axboe -- 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
