On 06/21/2018 01:51 AM, David Sterba wrote:
The stale device list removal needs to be protected by device_list_mutex
too as this could delete from the list and could race with another list
modification and cause crash.
The device needs to be fully initialized before it's added to the list
so the fs_devices also need to be set under the mutex.
Signed-off-by: David Sterba <dste...@suse.com>
---
fs/btrfs/volumes.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1da162928d1a..02246f9af0a3 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -791,12 +791,11 @@ static noinline struct btrfs_device
*device_list_add(const char *path,
rcu_assign_pointer(device->name, name);
mutex_lock(&fs_devices->device_list_mutex);
+ device->fs_devices = fs_devices;
list_add_rcu(&device->dev_list, &fs_devices->devices);
fs_devices->num_devices++;
- mutex_unlock(&fs_devices->device_list_mutex);
-
- device->fs_devices = fs_devices;
btrfs_free_stale_devices(path, device);
This is not correct.
btrfs_free_stale_devices need the per fs_devices local device_list_mutex
lock as it traverses through the fs_uuids list. Holding just the lock of
the %fs_devices which is being scanned or mounted is not correct.
In my workspace I have replaced this patch with ..
4130724ec926 btrfs: fix btrfs_free_stale_devices() with needed locks
90fedec0c200 btrfs: btrfs_free_stale_devices() rename local variables
439eec4e943c btrfs: fix device_list_add() missing device_list_mutex()
417ecc91e223 btrfs: do btrfs_free_stale_devices() outside of
device_list_add()
which are in the ML as well.
Thanks, Anand
+ mutex_unlock(&fs_devices->device_list_mutex);
if (disk_super->label[0])
pr_info("BTRFS: device label %s devid %llu transid %llu
%s\n",
--
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