On Mon, Feb 3, 2014 at 6:27 PM, Sage Weil <[email protected]> wrote:
> On Mon, 3 Feb 2014, Ilya Dryomov wrote:
>> With the addition of erasure coding support in the future, scratch
>> variable-length array in crush_do_rule_ary() is going to grow to at
>> least 200 bytes on average, on top of another 128 bytes consumed by
>> rawosd/osd arrays in the call chain. Replace it with a buffer inside
>> struct osdmap and a mutex. This shouldn't result in any contention,
>> because all osd requests were already serialized by request_mutex at
>> that point; the only unlocked caller was ceph_ioctl_get_dataloc().
>>
>> Signed-off-by: Ilya Dryomov <[email protected]>
>> ---
>> include/linux/ceph/osdmap.h | 3 +++
>> net/ceph/osdmap.c | 25 ++++++++++++++++---------
>> 2 files changed, 19 insertions(+), 9 deletions(-)
>>
>> diff --git a/include/linux/ceph/osdmap.h b/include/linux/ceph/osdmap.h
>> index 49ff69f0746b..8c8b3cefc28b 100644
>> --- a/include/linux/ceph/osdmap.h
>> +++ b/include/linux/ceph/osdmap.h
>> @@ -84,6 +84,9 @@ struct ceph_osdmap {
>> /* the CRUSH map specifies the mapping of placement groups to
>> * the list of osds that store+replicate them. */
>> struct crush_map *crush;
>> +
>> + struct mutex crush_scratch_mutex;
>> + int crush_scratch_ary[CEPH_PG_MAX_SIZE * 3];
>
> There are no users for CEPH_PG_MAX_SIZE (16) in the userland code. I
> would stick in a BUG_ON or WARN_ON just to make sure we don't get an
> OSDMap with more OSDs than that.
That IMO should be a separate patch. This patch doesn't change
existing semantics: CEPH_PG_MAX_SIZE is used throughout libceph to size
osd arrays. I'm not sure what happens if we get an osdmap wider than
16, but this buffer isn't overflown. See the BUG_ON below.
>
>> };
>>
>> static inline void ceph_oid_set_name(struct ceph_object_id *oid,
>> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
>> index aade4a5c1c07..9d1aaa24def6 100644
>> --- a/net/ceph/osdmap.c
>> +++ b/net/ceph/osdmap.c
>> @@ -698,7 +698,9 @@ struct ceph_osdmap *osdmap_decode(void **p, void *end)
>> map = kzalloc(sizeof(*map), GFP_NOFS);
>> if (map == NULL)
>> return ERR_PTR(-ENOMEM);
>> +
>> map->pg_temp = RB_ROOT;
>> + mutex_init(&map->crush_scratch_mutex);
>>
>> ceph_decode_16_safe(p, end, version, bad);
>> if (version > 6) {
>> @@ -1142,14 +1144,20 @@ int ceph_oloc_oid_to_pg(struct ceph_osdmap *osdmap,
>> }
>> EXPORT_SYMBOL(ceph_oloc_oid_to_pg);
>>
>> -static int crush_do_rule_ary(const struct crush_map *map, int ruleno, int x,
>> - int *result, int result_max,
>> - const __u32 *weight, int weight_max)
>> +static int do_crush(struct ceph_osdmap *map, int ruleno, int x,
>> + int *result, int result_max,
>> + const __u32 *weight, int weight_max)
>> {
>> - int scratch[result_max * 3];
>> + int r;
>> +
>> + BUG_ON(result_max > CEPH_PG_MAX_SIZE);
This BUG_ON.
Thanks,
Ilya
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