On 10/19/2011 12:02 AM, Jan Schmidt wrote: > Hi there, > > while playing with snapshots for btrfs send, I also encountered > seemingly duplicate inodes, which are multiple > BTRFS_EMPTY_SUBVOL_DIR_OBJECTID objects within the same directory. I can > imagine software that feels uncomfortable, here. > > Such objects are created by btrfs_lookup_dentry() in fs/btrfs/inode.c > when ENOENT is encountered. > Hi, A similar bug has been fixed by one of my patches(still queued): http://marc.info/?l=linux-btrfs&m=131409014207238&w=2 thanks, liubo > The main purpose for this email is to ask: Is this going to stay like that? > > David Sterba sent a related issue some days ago with effects seen on > dcache level (subject: "WARNING: at fs/dcache.c:1256 > d_set_d_op+0xaa/0xc0() , nested snapshots"). > > I hit a bug when trying to rename(2) one of those objects, and I'm still > hitting it reproducably on 3.1-rc5. However, I cannot reproduce it with > the current for-linus branch (3.1-rc6). I don't see a commit I'd expect > to fix this, but it may be fixed: > > -- > Oct 17 13:28:26 oglaroon kernel: [266945.208573] btrfs failed to delete > reference to snap2, inode 257 parent 256 > Oct 17 13:28:26 oglaroon kernel: [266945.208586] ------------[ cut here > ]------------ > Oct 17 13:28:26 oglaroon kernel: [266945.264688] kernel BUG at > fs/btrfs/inode.c:6907! > Oct 17 13:28:26 oglaroon kernel: [266945.320807] invalid opcode: 0000 > [#1] SMP > Oct 17 13:28:26 oglaroon kernel: [266945.370907] CPU 2 > Oct 17 13:28:26 oglaroon kernel: [266945.393831] Modules linked in: > btrfs mpt2sas scsi_transport_sas raid_class [last unloaded: btrfs] > Oct 17 13:28:26 oglaroon kernel: [266945.503578] > Oct 17 13:28:26 oglaroon kernel: [266945.522353] Pid: 29567, comm: mv > Not tainted 3.1.0-rc4+ #5 Supermicro X8SIL/X8SIL > Oct 17 13:28:26 oglaroon kernel: [266945.613011] RIP: > 0010:[<ffffffffa06d906a>] [<ffffffffa06d906a>] btrfs_rename+0x42a/0x770 > [btrfs] > Oct 17 13:28:26 oglaroon kernel: [266945.720059] RSP: > 0018:ffff88022f933c78 EFLAGS: 00010282 > Oct 17 13:28:26 oglaroon kernel: [266945.784476] RAX: 00000000fffffffe > RBX: 000000003b2456a4 RCX: 0000000000000054 > Oct 17 13:28:26 oglaroon kernel: [266945.870675] RDX: 0000000000000053 > RSI: 000060fdc00042c0 RDI: ffff880234330000 > Oct 17 13:28:26 oglaroon kernel: [266945.956874] RBP: ffff88022f933d48 > R08: 0000000000000000 R09: 0000000000000001 > Oct 17 13:28:26 oglaroon kernel: [266946.043072] R10: 0000000000000006 > R11: 0000000000000000 R12: 000000004e9c1157 > Oct 17 13:28:26 oglaroon kernel: [266946.129270] R13: ffff880234468368 > R14: 0000000000000000 R15: ffff880234446d58 > Oct 17 13:28:26 oglaroon kernel: [266946.215471] FS: > 00007f3bf0b96700(0000) GS:ffff88023fc80000(0000) knlGS:0000000000000000 > Oct 17 13:28:26 oglaroon kernel: [266946.313080] CS: 0010 DS: 0000 ES: > 0000 CR0: 0000000080050033 > Oct 17 13:28:26 oglaroon kernel: [266946.382681] CR2: 00007f3bf0072110 > CR3: 000000015c05f000 CR4: 00000000000006e0 > Oct 17 13:28:26 oglaroon kernel: [266946.468880] DR0: 0000000000000000 > DR1: 0000000000000000 DR2: 0000000000000000 > Oct 17 13:28:26 oglaroon kernel: [266946.555079] DR3: 0000000000000000 > DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Oct 17 13:28:26 oglaroon kernel: [266946.641278] Process mv (pid: 29567, > threadinfo ffff88022f932000, task ffff880234330000) > Oct 17 13:28:26 oglaroon kernel: [266946.737849] Stack: > Oct 17 13:28:26 oglaroon kernel: [266946.762849] 000000000000000a > 0000000000000006 00000000000000d0 0000000000000000 > Oct 17 13:28:26 oglaroon kernel: [266946.852574] ffff88022f933c01 > 0000000000000101 00ff8802346b4158 ffff8802349b81b8 > Oct 17 13:28:26 oglaroon kernel: [266946.942299] 0000000000000000 > ffff88022f9e7000 ffff88022f9e7000 ffff88019d4b6aa8 > Oct 17 13:28:26 oglaroon kernel: [266947.032025] Call Trace: > Oct 17 13:28:26 oglaroon kernel: [266947.062215] [<ffffffff81189ea2>] > vfs_rename+0x162/0x3e0 > Oct 17 13:28:26 oglaroon kernel: [266947.126629] [<ffffffff8118bfb9>] > sys_renameat+0x239/0x270 > Oct 17 13:28:26 oglaroon kernel: [266947.193120] [<ffffffff8187568c>] ? > do_page_fault+0x20c/0x450 > Oct 17 13:28:26 oglaroon kernel: [266947.262722] [<ffffffff818723ca>] ? > retint_swapgs+0xe/0x13 > Oct 17 13:28:26 oglaroon kernel: [266947.329214] [<ffffffff810c84dd>] ? > trace_hardirqs_on_caller+0xfd/0x190 > Oct 17 13:28:26 oglaroon kernel: [266947.409185] [<ffffffff8118c006>] > sys_rename+0x16/0x20 > Oct 17 13:28:26 oglaroon kernel: [266947.471527] [<ffffffff8187983b>] > system_call_fastpath+0x16/0x1b > Oct 17 13:28:26 oglaroon kernel: [266947.544240] Code: 68 ff ff ff 48 8b > 4a 30 44 8b 4a 24 4c 8b 42 28 48 8b 55 90 4c 89 95 58 ff ff ff 44 88 9d > 50 ff ff ff e8 ba c0 ff ff 85 c0 74 4a <0f> 0b eb fe 48 8b 45 80 48 8b > b8 20 01 00 00 88 95 48 ff ff ff > Oct 17 13:28:26 oglaroon kernel: [266947.777216] RIP > [<ffffffffa06d906a>] btrfs_rename+0x42a/0x770 [btrfs] > Oct 17 13:28:26 oglaroon kernel: [266947.856259] RSP <ffff88022f933c78> > Oct 17 13:28:26 oglaroon kernel: [266947.899234] ---[ end trace > fd19520e3af48c17 ]--- > -- > > Reproducer for the curious: > > # mkfs.btrfs /dev/sdv2 > # mount /dev/sdv2 /mnt > # btrfs subvol snap /mnt /mnt/snap1 > # btrfs subvol snap /mnt /mnt/snap2 > # btrfs subvol snap /mnt /mnt/snap3 > > When snap2 was created, there was a dir item for snap1, so this is no > surprise: > > # ls -lai /mnt/snap2 > total 8 > 256 dr-xr-xr-x 1 root root 20 Jan 1 1970 . > 256 dr-xr-xr-x 1 root root 30 Jan 1 1970 .. > 2 drwxr-xr-x 1 root root 0 Oct 18 16:25 snap1 > > Inode 2 seems a bit strange, but stay tuned. When snap3 was created, > there were dir items for snap1 and snap2, so ... *drumroll* > > # ls -lai /mnt/snap3 > total 8 > 256 dr-xr-xr-x 1 root root 30 Jan 1 1970 . > 256 dr-xr-xr-x 1 root root 30 Jan 1 1970 .. > 2 drwxr-xr-x 1 root root 0 Oct 18 16:26 snap1 > 2 drwxr-xr-x 1 root root 0 Oct 18 16:26 snap2 > > -Jan > -- > 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
