Got another one [ 365.232703] ------------[ cut here ]------------ [ 365.244894] kernel BUG at fs/dcache.c:676! [ 365.244896] invalid opcode: 0000 [#1] SMP [ 365.244898] last sysfs file: /sys/devices/virtual/block/dm-13/uevent [ 365.244900] CPU 4 [ 365.244901] Modules linked in: btrfs zlib_deflate crc32c libcrc32c [ 365.244904] [ 365.244907] Pid: 5359, comm: mount Not tainted 2.6.34-rc2 #1 Not Available /Not Available [ 365.244910] RIP: 0010:[<ffffffff81101b02>] [<ffffffff81101b02>] shrink_dcache_for_umount_subtree+0x1b4/0x29d [ 365.244919] RSP: 0018:ffff88037b283c38 EFLAGS: 00010292 [ 365.244920] RAX: 0000000000000067 RBX: ffff88067b558400 RCX: 0000000000000000 [ 365.244922] RDX: ffff88038aa00000 RSI: 0000000000000046 RDI: ffff88037b283a88 [ 365.244924] RBP: ffff88037b283c68 R08: 0000000000018989 R09: 0000000000000000 [ 365.244926] R10: ffff8800000b95e0 R11: 0000007d7b2839b8 R12: ffff88067a99bb00 [ 365.244928] R13: 0000000000000000 R14: ffff88067a99bb60 R15: 0000000000000000 [ 365.244930] FS: 00007f9fb75c8730(0000) GS:ffff88038aa00000(0000) knlGS:0000000000000000 [ 365.244932] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 365.244934] CR2: 00007faafe17f850 CR3: 000000067c2c7000 CR4: 00000000000006e0 [ 365.244935] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 365.244937] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 365.244939] Process mount (pid: 5359, threadinfo ffff88037b282000, task ffff88037c6bb2e0) [ 365.244941] Stack: [ 365.244942] ffff88067b558668 ffff88067c3fb800 ffff88067b558400 ffffffffa0063670 [ 365.244944] <0> ffff88067b558400 ffff88067c3fd000 ffff88037b283c88 ffffffff81101c27 [ 365.244946] <0> ffff88037b283d94 ffff88067b558400 ffff88037b283ca8 ffffffff810f34e0 [ 365.244951] Call Trace: [ 365.244956] [<ffffffff81101c27>] shrink_dcache_for_umount+0x3c/0x4c [ 365.244961] [<ffffffff810f34e0>] generic_shutdown_super+0x1f/0x102 [ 365.244964] [<ffffffff810f3618>] kill_anon_super+0x16/0x4f [ 365.244967] [<ffffffff810f36bf>] deactivate_locked_super+0x43/0x63 [ 365.244979] [<ffffffffa0016a80>] btrfs_get_sb+0x65c/0x6ff [btrfs] [ 365.244984] [<ffffffff811080a0>] ? alloc_vfsmnt+0xa5/0x17a [ 365.244989] [<ffffffff810e2afa>] ? alloc_pages_current+0x9b/0xa4 [ 365.244992] [<ffffffff810f3791>] vfs_kern_mount+0xb2/0x16d [ 365.244995] [<ffffffff810f38b3>] do_kern_mount+0x4c/0xec [ 365.244997] [<ffffffff81108ead>] do_mount+0x765/0x7de [ 365.245000] [<ffffffff81107133>] ? copy_mount_options+0xd4/0x137 [ 365.245003] [<ffffffff81108faa>] sys_mount+0x84/0xbe [ 365.245007] [<ffffffff8140f91a>] ? trace_hardirqs_on_thunk+0x3a/0x3c [ 365.245011] [<ffffffff81002c1b>] system_call_fastpath+0x16/0x1b [ 365.245013] Code: 38 49 8b 44 24 10 48 85 c0 74 04 48 8b 50 40 48 8d 86 68 02 00 00 48 c7 c7 7e da 76 81 48 89 04 24 4c 89 e6 31 c0 e8 62 be 30 00 <0f> 0b eb fe 49 8b 5c 24 28 49 39 dc 75 04 31 db eb 03 f0 ff 0b [ 365.245028] RIP [<ffffffff81101b02>] shrink_dcache_for_umount_subtree+0x1b4/0x29d [ 365.245031] RSP <ffff88037b283c38> [ 365.245038] ---[ end trace 96c601e4dd23e97f ]--- On 03/21/2010 10:45 PM, Alexander Piavlo wrote: > Hi, > trying the new btrfs tool and set-default with 2.6.34-rc2 i hit the the > following problem: > > mkfs.btrfs -d single /dev/sys/btrfs > mount -t btrfs /dev/sys/btrfs /btrfs > btrfs subvolume create /btrfs/newroot > mkdir /btrfs/newroot/.btrfs > btrfs subvolume set-default 256 /btrfs > umount /btrfs > mount -t btrfs /dev/sys/btrfs /btrfs > > up till now everything works ok > > A question How do i access or mount the original root of btrfs? Which > tree id does it have? > It would be great if "btrfs subvolume list ..." would also list the > original root. > > I guessed I need to use 0, so i tried: > mount -t btrfs -o subvol=0 /dev/sys/btrfs /btrfs/.btrfs > and: > mount -t btrfs -o subvol=. /dev/sys/btrfs /btrfs/.btrfs > but in both cases it mounted the newroot subvolume with id 256 under > /btrfs/.btrfs > > So I tried setting the original root back with: > btrfs subvolume set-default 0 /btrfs > > and next umount with: > umount /btrfs > BUT the unmount got stuck and i got the following trace > > > > [72657.249428] BUG: unable to handle kernel NULL pointer dereference at 00000000000001e0 > [72657.256085] IP: [<ffffffff8111493a>] bio_get_nr_vecs+0x10/0x3b > [72657.269999] PGD 0 > [72657.271328] Oops: 0000 [#2] SMP > [72657.274228] last sysfs file: /sys/devices/virtual/block/dm-13/uevent > [72657.290252] CPU 8 > [72657.291527] Modules linked in: btrfs zlib_deflate crc32c libcrc32c > [72657.309520] > [72657.310450] Pid: 22580, comm: flush-btrfs-16 Tainted: G D 2.6.34-rc2 #1 Not Available /Not Available > [72657.330925] RIP: 0010:[<ffffffff8111493a>] [<ffffffff8111493a>] bio_get_nr_vecs+0x10/0x3b > [72657.338377] RSP: 0018:ffff88037ce639a0 EFLAGS: 00010246 > [72657.351905] RAX: 0000000000000000 RBX: 0000000000000100 RCX: > 000000000000e060 > [72657.369112] RDX: ffffea0016b094a8 RSI: ffff88037c2aea10 RDI: > ffff88067e2eb0c0 > [72657.376303] RBP: ffff88037ce639a0 R08: 0000000000001000 R09: > 0000000000000000 > [72657.391338] R10: 0008000000000000 R11: dead000000100100 R12: > 0000000000000000 > [72657.409371] R13: 0000000000000000 R14: 0000000000001000 R15: > 0000000000001c0c > [72657.413345] FS: 0000000000000000(0000) GS:ffff880002100000(0000) > knlGS:0000000000000000 > [72657.431689] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [72657.435338] CR2: 00000000000001e0 CR3: 0000000001a1b000 CR4: > 00000000000006e0 > [72657.452048] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > 0000000000000000 > [72657.469286] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: > 0000000000000400 > [72657.474437] Process flush-btrfs-16 (pid: 22580, threadinfo > ffff88037ce62000, task ffff88037be74c50) > [72657.492828] Stack: > [72657.494314] ffff88037ce63a00 ffffffffa0046cde 0000000000000000 > 000000000000e060 > [72657.512301] <0> ffffea0016b094a8 ffff88037c2aea10 0000044100000282 > ffffea0016b094a8 > [72657.530760] <0> ffffea0016b094a8 0000000001c0c000 0000000000001c0d > 0000000000001c0c > [72657.536518] Call Trace: > [72657.549071] [<ffffffffa0046cde>] submit_extent_page+0xfd/0x1c1 [btrfs] > [72657.551996] [<ffffffffa004ada4>] __extent_writepage+0x598/0x5f4 [btrfs] > [72657.569734] [<ffffffffa0048e8f>] ? > end_bio_extent_writepage+0x0/0x160 [btrfs] > [72657.589129] [<ffffffff810bd916>] ? activate_page+0x146/0x156 > [72657.593942] [<ffffffffa0048403>] > extent_write_cache_pages+0x16c/0x257 [btrfs] > [72657.609762] [<ffffffffa0046de5>] ? flush_write_bio+0x0/0x10 [btrfs] > [72657.612899] [<ffffffffa004a80c>] ? __extent_writepage+0x0/0x5f4 [btrfs] > [72657.629600] [<ffffffff8103ae11>] ? load_balance+0x351/0xef1 > [72657.631840] [<ffffffffa0048542>] extent_writepages+0x54/0x69 [btrfs] > [72657.651442] [<ffffffffa002a5f0>] ? btree_get_extent+0x0/0x190 [btrfs] > [72657.668832] [<ffffffff81058682>] ? bit_waitqueue+0x19/0xa8 > [72657.671772] [<ffffffffa002b055>] btree_writepages+0x53/0x59 [btrfs] > [72657.688819] [<ffffffff810bc236>] do_writepages+0x21/0x2a > [72657.692005] [<ffffffff8110c3eb>] writeback_single_inode+0xe2/0x2d7 > [72657.709688] [<ffffffff8110d0c3>] writeback_inodes_wb+0x36e/0x44f > [72657.714306] [<ffffffff8110d2e3>] wb_writeback+0x13f/0x1ba > [72657.729897] [<ffffffff8108c526>] ? call_rcu_sched+0x15/0x17 > [72657.733276] [<ffffffff8108c536>] ? call_rcu+0xe/0x10 > [72657.754040] [<ffffffff8110d49a>] wb_do_writeback+0x7a/0x161 > [72657.757423] [<ffffffff8110d5c0>] bdi_writeback_task+0x3f/0xad > [72657.770202] [<ffffffff810c9962>] ? bdi_start_fn+0x0/0xd6 > [72657.774697] [<ffffffff810c99d8>] bdi_start_fn+0x76/0xd6 > [72657.790365] [<ffffffff810c9962>] ? bdi_start_fn+0x0/0xd6 > [72657.794878] [<ffffffff810582a8>] kthread+0x82/0x8a > [72657.808548] [<ffffffff81003a14>] kernel_thread_helper+0x4/0x10 > [72657.812371] [<ffffffff81410029>] ? restore_args+0x0/0x30 > [72657.828787] [<ffffffff81058226>] ? kthread+0x0/0x8a > [72657.832409] [<ffffffff81003a10>] ? kernel_thread_helper+0x0/0x10 > [72657.848453] Code: 48 8d 47 44 f0 ff 08 0f 94 c2 84 d2 74 0b 48 c7 47 > 08 00 00 00 00 ff 51 68 c9 c3 55 48 89 e5 0f 1f 44 00 00 48 8b 87 90 00 > 00 00 <48> 8b 80 e0 01 00 00 8b 90 34 04 00 00 0f b7 80 5a 04 00 00 c1 > [72657.886666] RIP [<ffffffff8111493a>] bio_get_nr_vecs+0x10/0x3b > [72657.890247] RSP <ffff88037ce639a0> > [72657.894937] CR2: 00000000000001e0 > [72657.907995] ---[ end trace 0e660d939479d800 ]--- > > > BTW this is reproducible. > > Another issue the set-default accepts all garbage input for example: > btrfs subvolume set-default sfsdfsdfs /btrfs > > So it would be good if this command was a little more verbose , and > would print that setting the new mount root actually succeeded or not > and not always return silently. > > Thanks a lot > Alex > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
