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 <ngomp...@gmail.com>
Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
---
fs/btrfs/dev-replace.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 3a9c1e046ebe..d05f73530af7 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -81,6 +81,9 @@ int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
struct btrfs_dev_replace_item *ptr;
u64 src_devid;
+ if (!dev_root)
+ return 0;
+
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
--
2.26.2
