On Fri, Jan 25, 2013 at 9:42 AM, Liu Bo <bo.li....@oracle.com> wrote: > On Fri, Jan 25, 2013 at 08:55:58AM -0600, Mitch Harder wrote: >> On Wed, Jan 23, 2013 at 6:52 PM, Liu Bo <bo.li....@oracle.com> wrote: >> > On Wed, Jan 23, 2013 at 10:05:04AM -0600, Mitch Harder wrote: >> >> On Wed, Jan 23, 2013 at 1:51 AM, Liu Bo <bo.li....@oracle.com> wrote: >> >> > On Tue, Jan 22, 2013 at 11:41:19AM -0600, Mitch Harder wrote: >> >> >> On Thu, Jan 17, 2013 at 8:42 AM, Mitch Harder >> >> >> <mitch.har...@sabayonlinux.org> wrote: >> >> >> > On Wed, Jan 16, 2013 at 6:36 AM, Liu Bo <bo.li....@oracle.com> wrote: >> >> >> >> This comes from one of btrfs's project ideas, >> >> >> >> As we defragment files, we break any sharing from other snapshots. >> >> >> >> The balancing code will preserve the sharing, and defrag needs to >> >> >> >> grow this >> >> >> >> as well. >> >> > [...] >> >> >> > >> >> >> > I've been testing this patch on a 3.7.2 kernel merged with the >> >> >> > for-linus branch for the 3.8_rc kernels, and I'm seeing the following >> >> >> > error: >> >> >> > >> >> >> >> >> >> I've reproduced the error with CONFIG_DEBUG_LIST enabled, which shows >> >> >> some problem with an entry in the list. >> >> >> >> >> >> [59312.260441] ------------[ cut here ]------------ >> >> >> [59312.260454] WARNING: at lib/list_debug.c:62 >> >> >> __list_del_entry+0x8d/0x98() >> >> >> [59312.260458] Hardware name: OptiPlex 745 >> >> >> [59312.260461] list_del corruption. next->prev should be >> >> >> ffff88006511c438, but was dead000000200200 >> >> > >> >> > LIST_POISON2 -> (000000200200) >> >> > So we can know that the next one is deleted from the list even _earlier_ >> >> > than the current one is. >> >> > >> >> > Any other messages before this warning complains? >> >> > >> >> >> >> Just some normal feedback from a metadata balance I had run. >> > >> > Well, these do fit my expectation, since balance also involves with >> > playing with >> > root_list, which may lead to the bad situation. >> > >> >> >> >> [14057.193343] device fsid 28c688c5-7dbd-4071-b271-1bf6726d8835 devid >> >> 1 transid 4 /dev/sda7 >> >> [14057.194438] btrfs: force lzo compression >> >> [14057.194446] btrfs: enabling auto defrag >> >> [14057.194449] btrfs: disk space caching is enabled >> >> [14057.194452] btrfs flagging fs with big metadata feature >> >> [14057.194455] btrfs: lzo incompat flag set. >> >> [57508.799193] btrfs: relocating block group 14516486144 flags 4 >> >> [57632.178797] btrfs: found 6775 extents >> >> [57633.214701] btrfs: relocating block group 11832131584 flags 4 >> >> [57776.400102] btrfs: found 6480 extents >> >> [57777.021175] btrfs: relocating block group 10489954304 flags 4 >> >> [57949.182725] btrfs: found 6681 extents >> >> [59312.260441] ------------[ cut here ]------------ >> >> [59312.260454] WARNING: at lib/list_debug.c:62 >> >> __list_del_entry+0x8d/0x98() >> >> [59312.260458] Hardware name: OptiPlex 745 >> >> ... >> >> >> >> I'm going to try to wrap some debugging around the section of code in >> >> btrfs_clean_old_snapshots() where the dead_roots list is spliced onto >> >> the root list being processed. The double entry may be slipping in >> >> here. >> >> >> >> 1764 spin_lock(&fs_info->trans_lock); >> >> 1765 list_splice_init(&fs_info->dead_roots, &list); >> >> 1766 spin_unlock(&fs_info->trans_lock); >> > >> > hmm, I don't think there is anything wrong in this code. But you can >> > give it a shot anyway :) >> > >> >> I've changed up my reproducer to try some things that may hit the >> issue quicker and more reliably. >> >> It gave me a slightly different set of warnings in dmesg, which seem >> to suggest issues in the dead_root list. > > Great! Many thanks for nail it down, we really shouldn't iput() > after btrfs_iget(). > > Could you please try this(remove iput()) and see if it gets us rid of > the trouble? > > thanks, > liubo > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 1683f48..c7a0fb7 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -2337,7 +2337,6 @@ out_free_path: > out_unlock: > unlock_extent_cached(&BTRFS_I(inode)->io_tree, lock_start, > lock_end, > &cached, GFP_NOFS); > - iput(inode); > return ret; > } >
With this patch, the cleaner never runs to delete the old roots. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
