On 12/19/2013 07:25 AM, Nicholas A. Bellinger wrote:
> On Wed, 2013-12-18 at 09:15 +0100, Hannes Reinecke wrote:
>> On 12/17/2013 09:49 PM, Nicholas A. Bellinger wrote:
>>> On Tue, 2013-12-17 at 09:18 +0100, Hannes Reinecke wrote:
>>>> Referrals need an LBA map, which needs to be kept
>>>> consistent across all target port groups. So
>>>> instead of tying the map to the target port groups
>>>> I've implemented a single attribute containing the
>>>> entire map.
>>>>
>>>> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
>>>> ---
>>>> drivers/target/target_core_alua.c | 101 +++++++++++++++++++
>>>> drivers/target/target_core_alua.h | 8 ++
>>>> drivers/target/target_core_configfs.c | 171 +++++++++++++++++++++++++++++++++
>>>> drivers/target/target_core_device.c | 1 +
>>>> drivers/target/target_core_transport.c | 28 +++++-
>>>> 5 files changed, 308 insertions(+), 1 deletion(-)
>>>>
>>>
>>> Applied, with one comment below..
>>>
>>> <SNIP>
>>>
>>>> diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
>>>> index e74ef8c..1dbc1bc 100644
>>>> --- a/drivers/target/target_core_configfs.c
>>>> +++ b/drivers/target/target_core_configfs.c
>>>> @@ -1741,6 +1741,176 @@ static struct target_core_configfs_attribute target_core_attr_dev_alua_lu_gp = {
>>>> .store = target_core_store_alua_lu_gp,
>>>> };
>>>>
>>>> +static ssize_t target_core_show_dev_lba_map(void *p, char *page)
>>>> +{
>>>> + struct se_device *dev = p;
>>>> + struct t10_alua_lba_map *map;
>>>> + struct t10_alua_lba_map_member *mem;
>>>> + char *b = page;
>>>> + int bl = 0;
>>>> + char state;
>>>> +
>>>> + spin_lock(&dev->t10_alua.lba_map_lock);
>>>> + if (!list_empty(&dev->t10_alua.lba_map_list))
>>>> + bl += sprintf(b + bl, "%u %u\n",
>>>> + dev->t10_alua.lba_map_segment_size,
>>>> + dev->t10_alua.lba_map_segment_multiplier);
>>>> + list_for_each_entry(map, &dev->t10_alua.lba_map_list, lba_map_list) {
>>>> + bl += sprintf(b + bl, "%llu %llu",
>>>> + map->lba_map_first_lba, map->lba_map_last_lba);
>>>> + list_for_each_entry(mem, &map->lba_map_mem_list,
>>>> + lba_map_mem_list) {
>>>> + switch (mem->lba_map_mem_alua_state) {
>>>> + case ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED:
>>>> + state = 'O';
>>>> + break;
>>>> + case ALUA_ACCESS_STATE_ACTIVE_NON_OPTIMIZED:
>>>> + state = 'A';
>>>> + break;
>>>> + case ALUA_ACCESS_STATE_STANDBY:
>>>> + state = 'S';
>>>> + break;
>>>> + case ALUA_ACCESS_STATE_UNAVAILABLE:
>>>> + state = 'U';
>>>> + break;
>>>> + default:
>>>> + state = '.';
>>>> + break;
>>>> + }
>>>> + bl += sprintf(b + bl, " %d:%c",
>>>> + mem->lba_map_mem_alua_pg_id, state);
>>>> + }
>>>> + bl += sprintf(b + bl, "\n");
>>>> + }
>>>> + spin_unlock(&dev->t10_alua.lba_map_lock);
>>>
>>> The above loop can possibly overflow the passed *page..
>>>
>> No. This is the reverse operation to the constructor in
>> target_core_store_dev_lba_map().
>>
>> Which (per definition) can only handle maps up to one page in size.
>>
>> And hence the resulting (formatted) map as constructed by
>> target_core_show_dev_lba_map() will also fit on one page.
>>
>
> Sure, but AFAICT nothing prevents target_core_store_dev_lba_map() ->
> core_alua_set_lba_map() from being called multiple times, and thus
> potentially increasing target_core_show_dev_lba_map() output to larger
> than PAGE_SIZE..
>
Multiple times?
Hmm. I had envisioned the 'store' function to store the entire map,
thereby invalidating / overwriting the old one.
Didn't I implement that logic?
Have to check ...
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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