Re: [PATCH 2/2] Btrfs: send, don't leave without decrementing clone root's send_progress

[David Sterba <dsterba@suse.cz>]

On Mon, Mar 02, 2015 at 08:53:53PM +0000, Filipe Manana wrote:
> If the clone root was not readonly or the dead flag was set on it, we were
> leaving without decrementing the root's send_progress counter (and before
> we just incremented it). If a concurrent snapshot deletion was in progress
> and ended up being aborted, it would be impossible to later attempt to
> delete again the snapshot, since the root's send_in_progress counter could
> never go back to 0.
> 
> We were also setting clone_sources_to_rollback to i + 1 too early - if we
> bailed out because the clone root we got is not readonly or flagged as dead
> we ended up later derreferencing a null pointer because we didn't assign
> the clone root to sctx->clone_roots[i].root:
> 
> 		for (i = 0; sctx && i < clone_sources_to_rollback; i++)
> 			btrfs_root_dec_send_in_progress(
> 					sctx->clone_roots[i].root);
> 
> So just don't increment the send_in_progress counter if the root is readonly
> or flagged as dead.
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: David Sterba <dsterba@suse.cz>