Hi Chris, Thanks for the report, I've figured it out and will send a fix.
This bug is caused by the part of cleanup code of commit cb517eabba4f109810dba2e5f37b0dcf22103065(Btrfs: cleanup the similar code of the fs root read) thanks, -liubo On Sat, May 10, 2014 at 08:08:28PM -0600, Chris Murphy wrote: > Summary is, existing btrfs fs is made into a seed device, mounting it mounts > read-only, add device to it, unmount, then mount again so it mounts rw, then > delete the seed device. I expect that everything on the seed device is moved > to the newly added device, while the seed device is unchanged (to later > unmake it a seed device). Idea is to make a fairly exactly copy of an > existing device including all subvolumes. > > What actually happens is an oops upon device delete. > > Setup: > kernel 3.15.0-0.rc5.git0.1.fc21.x86_64 > btrfs-progs 3.14 > /dev/sdb2 = existing btrfs fs > /dev/sdc3 = unformatted partition > > Steps: > > # btrfstune -S1 /dev/sdb2 > # mount /dev/sdb2 /mnt > mount: /dev/sdb2 is write-protected, mounting read-only > # btrfs device add /dev/sdc3 /mnt > Performing full device TRIM (75.90GiB) ... > # btrfs fi show > Label: 'rawhide' uuid: d372e5d1-386f-460c-b036-611469e0155e > Total devices 1 FS bytes used 7.55GiB > devid 1 size 79.31GiB used 11.04GiB path /dev/sda3 > > btrfs: utils.c:1769: get_fs_info: Assertion `!(ndevs >= > fi_args->num_devices)' failed. ## previously reported subject "bug adding > device to seed device, btrfs fi show fails" > > # umount /mnt > # mount /dev/sdc3 /mnt > # btrfs device delete /dev/sdb2 /mnt > > [ 778.992693] BTRFS info (device sdb2): relocating block group 20464009216 > flags 2 > ##mount rw occurs here > [ 1200.019460] BTRFS info (device sdc3): disk space caching is enabled > [ 1200.036656] BTRFS: checking UUID tree > [ 1200.037194] SELinux: initialized (dev sdc3, type btrfs), uses xattr > [ 1220.761243] BUG: unable to handle kernel NULL pointer dereference at > 00000000000001e8 > [ 1220.761433] IP: [<ffffffffa00d3883>] btrfs_shrink_device+0x33/0x420 [btrfs] > [ 1220.761614] PGD 7fe9e067 PUD 80379067 PMD 0 > [ 1220.761758] Oops: 0000 [#1] SMP > [ 1220.761979] Modules linked in: fuse msdos xfs libcrc32c xt_CHECKSUM > ipt_MASQUERADE tun ip6t_rpfilter ip6t_REJECT xt_conntrack ebtable_nat > ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_nat > nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle > ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat > nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack > iptable_mangle iptable_security iptable_raw vfat fat ppdev sunrpc serio_raw > microcode parport_pc parport virtio_net i2c_piix4 i2c_core btrfs xor raid6_pq > virtio_pci virtio virtio_ring ata_generic pata_acpi > [ 1220.761979] CPU: 0 PID: 3469 Comm: btrfs Not tainted > 3.15.0-0.rc5.git0.1.fc21.x86_64 #1 > [ 1220.761979] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS > VirtualBox 12/01/2006 > [ 1220.761979] task: ffff88007ff413a0 ti: ffff88009e376000 task.ti: > ffff88009e376000 > [ 1220.761979] RIP: 0010:[<ffffffffa00d3883>] [<ffffffffa00d3883>] > btrfs_shrink_device+0x33/0x420 [btrfs] > [ 1220.761979] RSP: 0018:ffff88009e377c58 EFLAGS: 00010246 > [ 1220.761979] RAX: 0000000000000000 RBX: 0000000000000000 RCX: > 0000000000000000 > [ 1220.761979] RDX: 000000000000000f RSI: 0000000000000000 RDI: > ffff88003e04fc00 > [ 1220.761979] RBP: ffff88009e377ce8 R08: 0000000000000000 R09: > 00000000000000c1 > [ 1220.761979] R10: ffff88003e04fc00 R11: 0000000000000020 R12: > ffff88009453ebc8 > [ 1220.761979] R13: 0000000000000001 R14: 0000000000000000 R15: > ffff88003e04fc00 > [ 1220.761979] FS: 00007f18f112e880(0000) GS:ffff88009d400000(0000) > knlGS:0000000000000000 > [ 1220.761979] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 1220.761979] CR2: 00000000000001e8 CR3: 000000007fd6b000 CR4: > 00000000000006f0 > [ 1220.761979] Stack: > [ 1220.761979] 00000000c3c73881 ffffffff812231fd ffff88009453ebc8 > 0000000000000082 > [ 1220.761979] 0000000000000000 ffff88009e377d18 ffff88009e377cb8 > ffffffffa00ce482 > [ 1220.761979] ffff88009f3fa900 ffff8800853be020 ffff8800853be10b > 0000000000000001 > [ 1220.761979] Call Trace: > [ 1220.761979] [<ffffffff812231fd>] ? _submit_bh+0x15d/0x230 > [ 1220.761979] [<ffffffffa00ce482>] ? __find_device+0x52/0x80 [btrfs] > [ 1220.761979] [<ffffffffa00d6784>] btrfs_rm_device+0x2e4/0x880 [btrfs] > [ 1220.761979] [<ffffffffa00e0db5>] btrfs_ioctl+0x1f95/0x2880 [btrfs] > [ 1220.761979] [<ffffffff811a57cf>] ? handle_mm_fault+0x6bf/0x10f0 > [ 1220.761979] [<ffffffff811fa692>] ? final_putname+0x22/0x50 > [ 1220.761979] [<ffffffff811fa949>] ? putname+0x29/0x40 > [ 1220.761979] [<ffffffff81200f32>] ? user_path_at_empty+0x72/0xd0 > [ 1220.761979] [<ffffffff8170c2fc>] ? __do_page_fault+0x26c/0x580 > [ 1220.761979] [<ffffffff811f4427>] ? cp_new_stat+0x157/0x190 > [ 1220.761979] [<ffffffff81203670>] do_vfs_ioctl+0x2d0/0x4b0 > [ 1220.761979] [<ffffffff812038d1>] SyS_ioctl+0x81/0xa0 > [ 1220.761979] [<ffffffff817119e9>] system_call_fastpath+0x16/0x1b > [ 1220.761979] Code: e5 41 57 41 56 41 55 41 54 49 89 ff 53 48 89 f3 48 83 ec > 68 4c 8b 77 28 48 89 75 90 65 48 8b 04 25 28 00 00 00 48 89 45 d0 31 c0 <49> > 8b 86 e8 01 00 00 48 8b 80 c0 02 00 00 48 89 85 78 ff ff ff > [ 1220.761979] RIP [<ffffffffa00d3883>] btrfs_shrink_device+0x33/0x420 > [btrfs] > [ 1220.761979] RSP <ffff88009e377c58> > [ 1220.761979] CR2: 00000000000001e8 > [ 1220.803856] ---[ end trace 8df409055cb58c83 ]--- > > > Chris Murphy > > -- > 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 -- 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
