Re: [PATCH] btrfs: zoned: fix missing rcu locking in error message when loading zone info

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2024/10/2 23:45, fdmanana@kernel.org 写道:
> From: Filipe Manana <fdmanana@suse.com>
>
> At btrfs_load_zone_info() we have an error path that is dereferecing the
> name of a device which is a RCU string but we are not holding a RCU read
> lock, which is incorrect.
>
> Fix this by using btrfs_err_in_rcu() instead of btrfs_err().
>
> The problem is there since commit 08e11a3db098 ("btrfs: zoned: load zone's
> allocation offset"), back then at btrfs_load_block_group_zone_info() but
> then later on that code was factored out into the helper
> btrfs_load_zone_info() by commit 09a46725cc84 ("btrfs: zoned: factor out
> per-zone logic from btrfs_load_block_group_zone_info").
>
> Fixes: 08e11a3db098 ("btrfs: zoned: load zone's allocation offset")
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu
> ---
>   fs/btrfs/zoned.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
> index 00a016691d8e..dbcbf754d284 100644
> --- a/fs/btrfs/zoned.c
> +++ b/fs/btrfs/zoned.c
> @@ -1340,7 +1340,7 @@ static int btrfs_load_zone_info(struct btrfs_fs_info *fs_info, int zone_idx,
>   	switch (zone.cond) {
>   	case BLK_ZONE_COND_OFFLINE:
>   	case BLK_ZONE_COND_READONLY:
> -		btrfs_err(fs_info,
> +		btrfs_err_in_rcu(fs_info,
>   		"zoned: offline/readonly zone %llu on device %s (devid %llu)",
>   			  (info->physical >> device->zone_info->zone_size_shift),
>   			  rcu_str_deref(device->name), device->devid);