From: Josef Bacik josef@toxicpanda.com
commit 3cb894972f1809aa8d087c42e5e8b26c64b7d508 upstream.
While helping Neal fix his broken file system I added a debug patch to catch if we were calling btrfs_search_slot with a NULL root, and this stack trace popped:
we tried to search with a NULL root CPU: 0 PID: 1760 Comm: mount Not tainted 5.11.0-155.nealbtrfstest.1.fc34.x86_64 #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/22/2020 Call Trace: dump_stack+0x6b/0x83 btrfs_search_slot.cold+0x11/0x1b ? btrfs_init_dev_replace+0x36/0x450 btrfs_init_dev_replace+0x71/0x450 open_ctree+0x1054/0x1610 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: 0033:0x7f644730352e
Fix this by not starting the device replace stuff if we do not have a NULL dev root.
Reported-by: Neal Gompa ngompa13@gmail.com CC: stable@vger.kernel.org # 5.11+ Signed-off-by: Josef Bacik josef@toxicpanda.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/dev-replace.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -80,6 +80,9 @@ int btrfs_init_dev_replace(struct btrfs_ struct btrfs_dev_replace_item *ptr; u64 src_devid;
+ if (!dev_root) + return 0; + path = btrfs_alloc_path(); if (!path) { ret = -ENOMEM;