From: Wang Xiaoguang <wangxg.f...@cn.fujitsu.com>
Introduce static function inmem_search() to handle the job for in-memory
hash tree.
The trick is, we must ensure the delayed ref head is not being run at
the time we search the for the hash.
With inmem_search(), we can implement the btrfs_dedup_search()
interface.
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
Signed-off-by: Wang Xiaoguang <wangxg.f...@cn.fujitsu.com>
---
fs/btrfs/dedup.c | 180 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 180 insertions(+)
diff --git a/fs/btrfs/dedup.c b/fs/btrfs/dedup.c
index ed18fc9..dbcfcc9 100644
--- a/fs/btrfs/dedup.c
+++ b/fs/btrfs/dedup.c
@@ -363,3 +363,183 @@ int btrfs_dedup_disable(struct btrfs_fs_info *fs_info)
kfree(dedup_info);
return 0;
}
+
+/*
+ * Caller must ensure the corresponding ref head is not being run.
+ */
+static struct inmem_hash *
+inmem_search_hash(struct btrfs_dedup_info *dedup_info, u8 *hash)
+{
+ struct rb_node **p = &dedup_info->hash_root.rb_node;
+ struct rb_node *parent = NULL;
+ struct inmem_hash *entry = NULL;
+ u16 hash_type = dedup_info->hash_type;
+ int hash_len = btrfs_dedup_sizes[hash_type];
+
+ while (*p) {
+ parent = *p;
+ entry = rb_entry(parent, struct inmem_hash, hash_node);
+
+ if (memcmp(hash, entry->hash, hash_len) < 0) {
+ p = &(*p)->rb_left;
+ } else if (memcmp(hash, entry->hash, hash_len) > 0) {
+ p = &(*p)->rb_right;
+ } else {
+ /* Found, need to re-add it to LRU list head */
+ list_del(&entry->lru_list);
+ list_add(&entry->lru_list, &dedup_info->lru_list);
+ return entry;
+ }
+ }
+ return NULL;
+}
+
+static int inmem_search(struct btrfs_dedup_info *dedup_info,
+ struct inode *inode, u64 file_pos,
+ struct btrfs_dedup_hash *hash)
+{
+ int ret;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_delayed_ref_root *delayed_refs;
+ struct btrfs_delayed_ref_head *head;
+ struct btrfs_delayed_ref_head *insert_head;
+ struct btrfs_delayed_data_ref *insert_dref;
+ struct btrfs_qgroup_extent_record *insert_qrecord = NULL;
+ struct inmem_hash *found_hash;
+ int free_insert = 1;
+ u64 bytenr;
+ u32 num_bytes;
+
+ insert_head = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
+ if (!insert_head)
+ return -ENOMEM;
+ insert_head->extent_op = NULL;
+ insert_dref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
+ if (!insert_dref) {
+ kmem_cache_free(btrfs_delayed_ref_head_cachep, insert_head);
+ return -ENOMEM;
+ }
+ if (root->fs_info->quota_enabled &&
+ is_fstree(root->root_key.objectid)) {
+ insert_qrecord = kmalloc(sizeof(*insert_qrecord), GFP_NOFS);
+ if (!insert_qrecord) {
+ kmem_cache_free(btrfs_delayed_ref_head_cachep,
+ insert_head);
+ kmem_cache_free(btrfs_delayed_data_ref_cachep,
+ insert_dref);
+ return -ENOMEM;
+ }
+ }
+
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto free_mem;
+ }
+
+again:
+ mutex_lock(&dedup_info->lock);
+ found_hash = inmem_search_hash(dedup_info, hash->hash);
+ /* If we don't find a duplicated extent, just return. */
+ if (!found_hash) {
+ ret = 0;
+ goto out;
+ }
+ bytenr = found_hash->bytenr;
+ num_bytes = found_hash->num_bytes;
+
+ delayed_refs = &trans->transaction->delayed_refs;
+
+ spin_lock(&delayed_refs->lock);
+ head = btrfs_find_delayed_ref_head(trans, bytenr);
+ if (!head) {
+ /*
+ * We can safely insert a new delayed_ref as long as we
+ * hold delayed_refs->lock.
+ * Only need to use atomic inc_extent_ref()
+ */
+ btrfs_add_delayed_data_ref_locked(root->fs_info, trans,
+ insert_dref, insert_head, insert_qrecord,
+ bytenr, num_bytes, 0, root->root_key.objectid,
+ btrfs_ino(inode), file_pos, 0,
+ BTRFS_ADD_DELAYED_REF);
+ spin_unlock(&delayed_refs->lock);
+
+ /* add_delayed_data_ref_locked will free unused memory */
+ free_insert = 0;
+ hash->bytenr = bytenr;
+ hash->num_bytes = num_bytes;
+ ret = 1;
+ goto out;
+ }
+
+ /*
+ * We can't lock ref head with dedup_info->lock hold or we will cause
+ * ABBA dead lock.
+ */
+ mutex_unlock(&dedup_info->lock);
+ ret = btrfs_delayed_ref_lock(trans, head);
+ spin_unlock(&delayed_refs->lock);
+ if (ret == -EAGAIN)
+ goto again;
+
+ mutex_lock(&dedup_info->lock);
+ /* Search again to ensure the hash is still here */
+ found_hash = inmem_search_hash(dedup_info, hash->hash);
+ if (!found_hash) {
+ ret = 0;
+ mutex_unlock(&head->mutex);
+ goto out;
+ }
+ hash->bytenr = bytenr;
+ hash->num_bytes = num_bytes;
+
+ /*
+ * Increase the extent ref right now, to avoid delayed ref run
+ * Or we may increase ref on non-exist extent.
+ */
+ btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
+ root->root_key.objectid,
+ btrfs_ino(inode), file_pos);
+ mutex_unlock(&head->mutex);
+out:
+ mutex_unlock(&dedup_info->lock);
+ btrfs_end_transaction(trans, root);
+
+free_mem:
+ if (free_insert) {
+ kmem_cache_free(btrfs_delayed_ref_head_cachep, insert_head);
+ kmem_cache_free(btrfs_delayed_data_ref_cachep, insert_dref);
+ kfree(insert_qrecord);
+ }
+ return ret;
+}
+
+int btrfs_dedup_search(struct btrfs_fs_info *fs_info,
+ struct inode *inode, u64 file_pos,
+ struct btrfs_dedup_hash *hash)
+{
+ struct btrfs_dedup_info *dedup_info = fs_info->dedup_info;
+ int ret = -EINVAL;
+
+ if (!hash)
+ return 0;
+
+ /*
+ * This function doesn't follow fs_info->dedup_enabled as it will need
+ * to ensure any hashed extent to go through dedup routine
+ */
+ if (WARN_ON(dedup_info == NULL))
+ return -EINVAL;
+
+ if (dedup_info->backend == BTRFS_DEDUP_BACKEND_INMEMORY)
+ ret = inmem_search(dedup_info, inode, file_pos, hash);
+
+ /* It's possible hash->bytenr/num_bytenr already changed */
+ if (ret == 0) {
+ hash->num_bytes = 0;
+ hash->bytenr = 0;
+ }
+ return ret;
+}
--
2.7.0
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