@@ -493,6 +493,172 @@ int btrfs_dedup_disable(struct btrfs_fs_info *fs_info)
}
/*
+ * Return 0 for not found
+ * Return >0 for found and set bytenr_ret
+ * Return <0 for error
+ */
+static int ondisk_search_hash(struct btrfs_dedup_info *dedup_info, u8 *hash,
+ u64 *bytenr_ret, u64 *num_bytes_ret)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct btrfs_root *dedup_root = dedup_info->dedup_root;
+ u8 *buf = NULL;
+ u64 hash_key;
+ int hash_len = btrfs_dedup_sizes[dedup_info->hash_type];
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ buf = kmalloc(hash_len, GFP_NOFS);
+ if (!buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ memcpy(&hash_key, hash + hash_len - 8, 8);
+ key.objectid = hash_key;
+ key.type = BTRFS_DEDUP_HASH_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(NULL, dedup_root, &key, path, 0, 0);
+ if (ret < 0)
+ goto out;
+ WARN_ON(ret == 0);
+ while (1) {
+ struct extent_buffer *node;
+ struct btrfs_dedup_hash_item *hash_item;
+ int slot;
+
+ ret = btrfs_previous_item(dedup_root, path, hash_key,
+ BTRFS_DEDUP_HASH_ITEM_KEY);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = 0;
+ goto out;
+ }
+
+ node = path->nodes[0];
+ slot = path->slots[0];
+ btrfs_item_key_to_cpu(node, &key, slot);
+
+ if (key.type != BTRFS_DEDUP_HASH_ITEM_KEY ||
+ memcmp(&key.objectid, hash + hash_len - 8, 8))
+ break;
+ hash_item = btrfs_item_ptr(node, slot,
+ struct btrfs_dedup_hash_item);
+ read_extent_buffer(node, buf, (unsigned long)(hash_item + 1),
+ hash_len);
+ if (!memcmp(buf, hash, hash_len)) {
+ ret = 1;
+ *bytenr_ret = key.offset;
+ *num_bytes_ret = btrfs_dedup_hash_len(node, hash_item);
+ break;
+ }
+ }
+out:
+ kfree(buf);
+ btrfs_free_path(path);
+ return ret;
+}
+
+static int ondisk_search(struct inode *inode, u64 file_pos,
+ struct btrfs_dedup_hash *hash)
+{
+ int ret;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_trans_handle *trans = NULL;
+ struct btrfs_delayed_ref_root *delayed_refs;
+ struct btrfs_delayed_ref_head *head;
+ struct btrfs_dedup_info *dedup_info = fs_info->dedup_info;
+ u64 old_bytenr;
+ u64 bytenr;
+ u64 num_bytes;
+
+ /*
+ * TODO: Opitmized the superhot mutex.
+ */
+ mutex_lock(&dedup_info->ondisk_lock);
+ ret = ondisk_search_hash(dedup_info, hash->hash, &bytenr, &num_bytes);
+ mutex_unlock(&dedup_info->ondisk_lock);
+ if (ret <= 0)
+ goto out;
+
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+again:
+ delayed_refs = &trans->transaction->delayed_refs;
+
+ spin_lock(&delayed_refs->lock);
+ head = btrfs_find_delayed_ref_head(trans, bytenr);
+ if (!head || head->processing == 1) {
+ /*
+ * Somebody else may be trying to run the refs, the found
+ * duplicated extent may be freed, so here we just
+ * choose to abort this dedup handle.
+ * XXX: we need to find a better method to improve it.
+ */
+ spin_unlock(&delayed_refs->lock);
+ ret = 0;
+ goto out;
+ }
+
+ ret = btrfs_delayed_ref_lock(trans, head);
+ spin_unlock(&delayed_refs->lock);
+ if (ret == -EAGAIN) {
+ mutex_lock(&dedup_info->ondisk_lock);
+ ret = ondisk_search_hash(dedup_info, hash->hash, &bytenr,
+ &num_bytes);
+ mutex_unlock(&dedup_info->ondisk_lock);
+ if (ret <= 0)
+ goto out;
+ goto again;
+ }
+ /*
+ * Still need to search the hash again to ensure the hash is not
+ * deleted in run_delayed_refs
+ */
+ old_bytenr = bytenr;
+ mutex_lock(&dedup_info->ondisk_lock);
+ ret = ondisk_search_hash(dedup_info, hash->hash, &bytenr, &num_bytes);
+ if (ret <= 0) {
+ mutex_unlock(&dedup_info->ondisk_lock);
+ mutex_unlock(&head->mutex);
+ goto out;
+ }
+
+ /* bytenr changed, we need to relock the delayed_ref head */
+ if (old_bytenr != bytenr) {
+ mutex_unlock(&dedup_info->ondisk_lock);
+ mutex_unlock(&head->mutex);
+ goto again;
+ }
+
+ /*
+ * finally, we found the matching hash, increase extent ref right now
+ * to avoid delayed ref run it
+ */
+ btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
+ root->root_key.objectid,
+ btrfs_ino(inode), file_pos);
+ hash->bytenr = bytenr;
+ hash->num_bytes = num_bytes;
+ mutex_unlock(&dedup_info->ondisk_lock);
+ mutex_unlock(&head->mutex);
+ ret = 1;
+out:
+ if (trans)
+ btrfs_end_transaction(trans, root);
+ return ret;
+}
+
+/*
* Caller must ensure the corresponding ref head is not being run.
*/
static struct inmem_hash *
@@ -646,7 +812,8 @@ int btrfs_dedup_search(struct inode *inode, u64 file_pos,
if (dedup_info->backend == BTRFS_DEDUP_BACKEND_INMEMORY)
ret = inmem_search(inode, file_pos, hash);
-
+ if (dedup_info->backend == BTRFS_DEDUP_BACKEND_ONDISK)
+ ret = ondisk_search(inode, file_pos, hash);
/* It's possible hash->bytenr/num_bytenr already changed */
if (ret == 0) {
hash->num_bytes = 0;
@@ -138,6 +138,9 @@ int btrfs_dedup_calc_hash(struct btrfs_root *root, struct inode *inode,
* Return > 0 for a hash match, and the extent ref will be
* INCREASED.
* Return 0 for a hash miss. Nothing is done
+ * Return <0 for error.
+ *
+ * Only on-disk backedn may return error though.
*/
int btrfs_dedup_search(struct inode *inode, u64 file_pos,
struct btrfs_dedup_hash *hash);