Lukas Czerner <lczerner@xxxxxxxxxx> writes:
>> @@ -484,6 +485,29 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
>> }
>> }
>>
>> + /*
>> + * We use punch hole to reclaim the free space used by the
>> + * image a.k.a. discard. However we do support discard if
>> + * encryption is enabled, because it may give an attacker
>> + * useful information.
>> + */
>> + if (bio->bi_rw & REQ_DISCARD) {
>> + struct file *file = lo->lo_backing_file;
>> + int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
>> +
>> + if ((!file->f_op->fallocate) ||
>> + lo->lo_encrypt_key_size) {
>> + ret = -EOPNOTSUPP;
>> + goto out;
>> + }
>> + ret = file->f_op->fallocate(file, mode, pos,
>> + bio->bi_size);
>> + if (unlikely(ret && ret != -EINVAL &&
>> + ret != -EOPNOTSUPP))
>> + ret = -EIO;
>> + goto out;
>> + }
>> +
Seems you missed the bizarre case of configuring a loop device over top
of a block device.
Cheers,
Jeff
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