| 44 | int dmu_object_alloc_chunk_shift = 7; |
| 45 | |
| 46 | static uint64_t |
| 47 | dmu_object_alloc_impl(objset_t *os, dmu_object_type_t ot, int blocksize, |
| 48 | int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen, |
| 49 | int dnodesize, dnode_t **allocated_dnode, void *tag, dmu_tx_t *tx) |
| 50 | { |
| 51 | uint64_t object; |
| 52 | uint64_t L1_dnode_count = DNODES_PER_BLOCK << |
| 53 | (DMU_META_DNODE(os)->dn_indblkshift - SPA_BLKPTRSHIFT); |
| 54 | dnode_t *dn = NULL; |
| 55 | int dn_slots = dnodesize >> DNODE_SHIFT; |
| 56 | boolean_t restarted = B_FALSE; |
| 57 | uint64_t *cpuobj = NULL; |
| 58 | int dnodes_per_chunk = 1 << dmu_object_alloc_chunk_shift; |
| 59 | int error; |
| 60 | |
| 61 | cpuobj = &os->os_obj_next_percpu[CPU_SEQID_UNSTABLE % |
| 62 | os->os_obj_next_percpu_len]; |
| 63 | |
| 64 | if (dn_slots == 0) { |
| 65 | dn_slots = DNODE_MIN_SLOTS; |
| 66 | } else { |
| 67 | ASSERT3S(dn_slots, >=, DNODE_MIN_SLOTS); |
| 68 | ASSERT3S(dn_slots, <=, DNODE_MAX_SLOTS); |
| 69 | } |
| 70 | |
| 71 | /* |
| 72 | * The "chunk" of dnodes that is assigned to a CPU-specific |
| 73 | * allocator needs to be at least one block's worth, to avoid |
| 74 | * lock contention on the dbuf. It can be at most one L1 block's |
| 75 | * worth, so that the "rescan after polishing off a L1's worth" |
| 76 | * logic below will be sure to kick in. |
| 77 | */ |
| 78 | if (dnodes_per_chunk < DNODES_PER_BLOCK) |
| 79 | dnodes_per_chunk = DNODES_PER_BLOCK; |
| 80 | if (dnodes_per_chunk > L1_dnode_count) |
| 81 | dnodes_per_chunk = L1_dnode_count; |
| 82 | |
| 83 | /* |
| 84 | * The caller requested the dnode be returned as a performance |
| 85 | * optimization in order to avoid releasing the hold only to |
| 86 | * immediately reacquire it. Since they caller is responsible |
| 87 | * for releasing the hold they must provide the tag. |
| 88 | */ |
| 89 | if (allocated_dnode != NULL) { |
| 90 | ASSERT3P(tag, !=, NULL); |
| 91 | } else { |
| 92 | ASSERT3P(tag, ==, NULL); |
| 93 | tag = FTAG; |
| 94 | } |
| 95 | |
| 96 | object = *cpuobj; |
| 97 | for (;;) { |
| 98 | /* |
| 99 | * If we finished a chunk of dnodes, get a new one from |
| 100 | * the global allocator. |
| 101 | */ |
| 102 | if ((P2PHASE(object, dnodes_per_chunk) == 0) || |
| 103 | (P2PHASE(object + dn_slots - 1, dnodes_per_chunk) < |
no test coverage detected