Re: [PATCH 4/5] Btrfs: fix inode cache waiters hanging on path allocation failure

[Nikolay Borisov <nborisov@suse.com>]

On 4.07.19 г. 18:24 ч., fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> If the caching thread fails to allocate a path, it returns without waking
> up any cache waiters, leaving them hang forever. Fix this by following the
> same approach as when we fail to start the caching thread: print an error
> message, disable inode caching and make the wakers fallback to non-caching
> mode behaviour (calling btrfs_find_free_objectid()).
> 
> Fixes: 581bb050941b4f ("Btrfs: Cache free inode numbers in memory")
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

> ---
>  fs/btrfs/inode-map.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
> index 05b8c9927f29..4820e05ea6bd 100644
> --- a/fs/btrfs/inode-map.c
> +++ b/fs/btrfs/inode-map.c
> @@ -41,8 +41,10 @@ static int caching_kthread(void *data)
>  		return 0;
>  
>  	path = btrfs_alloc_path();
> -	if (!path)
> +	if (!path) {
> +		fail_caching_thread(root);
>  		return -ENOMEM;
> +	}
>  
>  	/* Since the commit root is read-only, we can safely skip locking. */
>  	path->skip_locking = 1;
>