On Sun, 1 Dec 2013, Lipeng Wan wrote: > Hi Dong, > > Thanks for your reply. Then is it valid to access the memory space > specified by that negative id? You'll notice that every time we index the bucket array, the index is something like -1 - id so that -1 maps to the first item, -2 to the second, etc. This is safe because it's always preceded by some check that id is < 0 (i.e., a bucket id). sage > > L Wan > > On Sun, Dec 1, 2013 at 10:31 PM, Dong Yuan <yuandong1222@xxxxxxxxx> wrote: > > If my memory serves me well, negative id means buckets (root, room, > > rack, cabinet, etc.), well positive means osds. > > > > On 2 December 2013 11:20, Lipeng Wan <lipengwan86@xxxxxxxxx> wrote: > >> Hi guys, > >> > >> I am reading the source code of ceph and trying to understand the data > >> structure of crush_map. Now I am confused by the use of "struct > >> crush_bucket **buckets" in function "int crush_do_rule(...)" in > >> src/crush/mapper.c. It seems that the index of array "map->buckets[]" > >> could be negative (see line 551, src/crush/mapper.c). I was wondering > >> if anyone could explain why the index of this array can be negative > >> and how those buckets were added into this array. Thanks. > >> > >> Best, > >> L. Wan > >> -- > >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > >> the body of a message to majordomo@xxxxxxxxxxxxxxx > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > > -- > > Dong Yuan > > Email:yuandong1222@xxxxxxxxx > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
