+
+ pg_id = lmv_hash_fnv1a(LMV_CRUSH_PG_COUNT, name, namelen);
+
+ /* distribute PG among all stripes pseudo-randomly, so they are almost
+ * evenly distributed, and when stripe count changes, only (delta /
+ * total) sub files need to be moved, herein 'delta' is added or removed
+ * stripe count, 'total' is total stripe count before change for
+ * removal, or count after change for addition.
+ */
+ for (i = 0; i < count; i++) {
+ straw = crush_hash(pg_id, i);
+ if (straw > highest_straw) {
+ highest_straw = straw;
+ idx = i;
+ }
+ }
+ LASSERT(idx < count);
+
+ return idx;
+}
+
+/* directory layout may change in three ways:
+ * 1. directory migration, in its LMV source stripes are appended after
+ * target stripes, \a migrate_hash is source hash type, \a migrate_offset is
+ * target stripe count,
+ * 2. directory split, \a migrate_hash is hash type before split,
+ * \a migrate_offset is stripe count before split.
+ * 3. directory merge, \a migrate_hash is hash type after merge,
+ * \a migrate_offset is stripe count after merge.
+ */
+static inline int
+__lmv_name_to_stripe_index(__u32 hash_type, __u32 stripe_count,
+ __u32 migrate_hash, __u32 migrate_offset,
+ const char *name, int namelen, bool new_layout)
+{
+ __u32 saved_hash = hash_type;
+ __u32 saved_count = stripe_count;
+ int stripe_index = 0;
+
+ LASSERT(namelen > 0);
+ LASSERT(stripe_count > 0);
+
+ if (lmv_hash_is_splitting(hash_type)) {
+ if (!new_layout) {
+ hash_type = migrate_hash;
+ stripe_count = migrate_offset;
+ }
+ } else if (lmv_hash_is_merging(hash_type)) {
+ if (new_layout) {
+ hash_type = migrate_hash;
+ stripe_count = migrate_offset;
+ }
+ } else if (lmv_hash_is_migrating(hash_type)) {
+ if (new_layout) {
+ stripe_count = migrate_offset;
+ } else {
+ hash_type = migrate_hash;
+ stripe_count -= migrate_offset;
+ }
+ }
+
+ if (stripe_count > 1) {
+ switch (hash_type & LMV_HASH_TYPE_MASK) {
+ case LMV_HASH_TYPE_ALL_CHARS:
+ stripe_index = lmv_hash_all_chars(stripe_count, name,
+ namelen);
+ break;
+ case LMV_HASH_TYPE_FNV_1A_64:
+ stripe_index = lmv_hash_fnv1a(stripe_count, name,
+ namelen);
+ break;
+ case LMV_HASH_TYPE_CRUSH:
+ stripe_index = lmv_hash_crush(stripe_count, name,
+ namelen);
+ break;
+ default:
+ return -EBADFD;
+ }
+ }
+
+ LASSERT(stripe_index < stripe_count);
+
+ if (!new_layout && lmv_hash_is_migrating(saved_hash))
+ stripe_index += migrate_offset;
+
+ LASSERT(stripe_index < saved_count);
+
+ CDEBUG(D_INFO, "name %.*s hash=%#x/%#x idx=%d/%u/%u under %s layout\n",
+ namelen, name, saved_hash, migrate_hash, stripe_index,
+ saved_count, migrate_offset, new_layout ? "new" : "old");
+
+ return stripe_index;
+}
+
+static inline int lmv_name_to_stripe_index(struct lmv_mds_md_v1 *lmv,
+ const char *name, int namelen)
+{
+ if (lmv->lmv_magic == LMV_MAGIC_V1)
+ return __lmv_name_to_stripe_index(lmv->lmv_hash_type,
+ lmv->lmv_stripe_count,
+ lmv->lmv_migrate_hash,
+ lmv->lmv_migrate_offset,
+ name, namelen, true);
+
+ if (lmv->lmv_magic == cpu_to_le32(LMV_MAGIC_V1))
+ return __lmv_name_to_stripe_index(
+ le32_to_cpu(lmv->lmv_hash_type),
+ le32_to_cpu(lmv->lmv_stripe_count),
+ le32_to_cpu(lmv->lmv_migrate_hash),
+ le32_to_cpu(lmv->lmv_migrate_offset),
+ name, namelen, true);
+
+ return -EINVAL;
+}
+
+static inline int lmv_name_to_stripe_index_old(struct lmv_mds_md_v1 *lmv,
+ const char *name, int namelen)
+{
+ if (lmv->lmv_magic == LMV_MAGIC_V1 ||
+ lmv->lmv_magic == LMV_MAGIC_STRIPE)
+ return __lmv_name_to_stripe_index(lmv->lmv_hash_type,
+ lmv->lmv_stripe_count,
+ lmv->lmv_migrate_hash,
+ lmv->lmv_migrate_offset,
+ name, namelen, false);
+
+ if (lmv->lmv_magic == cpu_to_le32(LMV_MAGIC_V1) ||
+ lmv->lmv_magic == cpu_to_le32(LMV_MAGIC_STRIPE))
+ return __lmv_name_to_stripe_index(
+ le32_to_cpu(lmv->lmv_hash_type),
+ le32_to_cpu(lmv->lmv_stripe_count),
+ le32_to_cpu(lmv->lmv_migrate_hash),
+ le32_to_cpu(lmv->lmv_migrate_offset),
+ name, namelen, false);
+
+ return -EINVAL;
+}
+
+static inline bool lmv_user_magic_supported(__u32 lum_magic)
+{
+ return lum_magic == LMV_USER_MAGIC ||
+ lum_magic == LMV_USER_MAGIC_SPECIFIC ||
+ lum_magic == LMV_MAGIC_FOREIGN;
+}
+
+/* master LMV is sane */
+static inline bool lmv_is_sane(const struct lmv_mds_md_v1 *lmv)
+{
+ if (!lmv)
+ return false;
+
+ if (le32_to_cpu(lmv->lmv_magic) != LMV_MAGIC_V1)
+ goto insane;
+
+ if (le32_to_cpu(lmv->lmv_stripe_count) == 0)
+ goto insane;
+
+ if (!lmv_is_known_hash_type(le32_to_cpu(lmv->lmv_hash_type)))
+ goto insane;
+
+ return true;
+insane:
+ LMV_DEBUG(D_ERROR, lmv, "insane");
+ return false;