From: Josef Bacik josef@toxicpanda.com
commit 82d62d06db404d03836cdabbca41d38646d97cbb upstream.
Neal reported a panic trying to use -o rescue=all
BUG: kernel NULL pointer dereference, address: 0000000000000030 PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 4095 Comm: mount Not tainted 5.11.0-0.rc7.149.fc34.x86_64 #1 RIP: 0010:btrfs_device_init_dev_stats+0x4c/0x1f0 RSP: 0018:ffffa60285fbfb68 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88b88f806498 RCX: ffff88b82e7a2a10 RDX: ffffa60285fbfb97 RSI: ffff88b82e7a2a10 RDI: 0000000000000000 RBP: ffff88b88f806b3c R08: 0000000000000000 R09: 0000000000000000 R10: ffff88b82e7a2a10 R11: 0000000000000000 R12: ffff88b88f806a00 R13: ffff88b88f806478 R14: ffff88b88f806a00 R15: ffff88b82e7a2a10 FS: 00007f698be1ec40(0000) GS:ffff88b937e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000030 CR3: 0000000092c9c006 CR4: 00000000003706f0 Call Trace: ? btrfs_init_dev_stats+0x1f/0xf0 btrfs_init_dev_stats+0x62/0xf0 open_ctree+0x1019/0x15ff btrfs_mount_root.cold+0x13/0xfa legacy_get_tree+0x27/0x40 vfs_get_tree+0x25/0xb0 vfs_kern_mount.part.0+0x71/0xb0 btrfs_mount+0x131/0x3d0 ? legacy_get_tree+0x27/0x40 ? btrfs_show_options+0x640/0x640 legacy_get_tree+0x27/0x40 vfs_get_tree+0x25/0xb0 path_mount+0x441/0xa80 __x64_sys_mount+0xf4/0x130 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f698c04e52e
This happens because we unconditionally attempt to initialize device stats on mount, but we may not have been able to read the device root. Fix this by skipping initializing the device stats if we do not have a device root.
Reported-by: Neal Gompa ngompa13@gmail.com CC: stable@vger.kernel.org # 5.11+ Signed-off-by: Josef Bacik josef@toxicpanda.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/volumes.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -7282,6 +7282,9 @@ static int btrfs_device_init_dev_stats(s int item_size; int i, ret, slot;
+ if (!device->fs_info->dev_root) + return 0; + key.objectid = BTRFS_DEV_STATS_OBJECTID; key.type = BTRFS_PERSISTENT_ITEM_KEY; key.offset = device->devid;