Btrfs: rename the scrub context structure
[linux-3.10.git] / fs / btrfs / backref.c
index fb56bcc..04edf69 100644 (file)
  * Boston, MA 021110-1307, USA.
  */
 
+#include <linux/vmalloc.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "backref.h"
 #include "ulist.h"
 #include "transaction.h"
 #include "delayed-ref.h"
+#include "locking.h"
+
+struct extent_inode_elem {
+       u64 inum;
+       u64 offset;
+       struct extent_inode_elem *next;
+};
+
+static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
+                               struct btrfs_file_extent_item *fi,
+                               u64 extent_item_pos,
+                               struct extent_inode_elem **eie)
+{
+       u64 data_offset;
+       u64 data_len;
+       struct extent_inode_elem *e;
+
+       data_offset = btrfs_file_extent_offset(eb, fi);
+       data_len = btrfs_file_extent_num_bytes(eb, fi);
+
+       if (extent_item_pos < data_offset ||
+           extent_item_pos >= data_offset + data_len)
+               return 1;
+
+       e = kmalloc(sizeof(*e), GFP_NOFS);
+       if (!e)
+               return -ENOMEM;
+
+       e->next = *eie;
+       e->inum = key->objectid;
+       e->offset = key->offset + (extent_item_pos - data_offset);
+       *eie = e;
+
+       return 0;
+}
+
+static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
+                               u64 extent_item_pos,
+                               struct extent_inode_elem **eie)
+{
+       u64 disk_byte;
+       struct btrfs_key key;
+       struct btrfs_file_extent_item *fi;
+       int slot;
+       int nritems;
+       int extent_type;
+       int ret;
+
+       /*
+        * from the shared data ref, we only have the leaf but we need
+        * the key. thus, we must look into all items and see that we
+        * find one (some) with a reference to our extent item.
+        */
+       nritems = btrfs_header_nritems(eb);
+       for (slot = 0; slot < nritems; ++slot) {
+               btrfs_item_key_to_cpu(eb, &key, slot);
+               if (key.type != BTRFS_EXTENT_DATA_KEY)
+                       continue;
+               fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
+               extent_type = btrfs_file_extent_type(eb, fi);
+               if (extent_type == BTRFS_FILE_EXTENT_INLINE)
+                       continue;
+               /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
+               disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
+               if (disk_byte != wanted_disk_byte)
+                       continue;
+
+               ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
+               if (ret < 0)
+                       return ret;
+       }
+
+       return 0;
+}
 
 /*
  * this structure records all encountered refs on the way up to the root
 struct __prelim_ref {
        struct list_head list;
        u64 root_id;
-       struct btrfs_key key;
+       struct btrfs_key key_for_search;
        int level;
        int count;
+       struct extent_inode_elem *inode_list;
        u64 parent;
        u64 wanted_disk_byte;
 };
 
+/*
+ * the rules for all callers of this function are:
+ * - obtaining the parent is the goal
+ * - if you add a key, you must know that it is a correct key
+ * - if you cannot add the parent or a correct key, then we will look into the
+ *   block later to set a correct key
+ *
+ * delayed refs
+ * ============
+ *        backref type | shared | indirect | shared | indirect
+ * information         |   tree |     tree |   data |     data
+ * --------------------+--------+----------+--------+----------
+ *      parent logical |    y   |     -    |    -   |     -
+ *      key to resolve |    -   |     y    |    y   |     y
+ *  tree block logical |    -   |     -    |    -   |     -
+ *  root for resolving |    y   |     y    |    y   |     y
+ *
+ * - column 1:       we've the parent -> done
+ * - column 2, 3, 4: we use the key to find the parent
+ *
+ * on disk refs (inline or keyed)
+ * ==============================
+ *        backref type | shared | indirect | shared | indirect
+ * information         |   tree |     tree |   data |     data
+ * --------------------+--------+----------+--------+----------
+ *      parent logical |    y   |     -    |    y   |     -
+ *      key to resolve |    -   |     -    |    -   |     y
+ *  tree block logical |    y   |     y    |    y   |     y
+ *  root for resolving |    -   |     y    |    y   |     y
+ *
+ * - column 1, 3: we've the parent -> done
+ * - column 2:    we take the first key from the block to find the parent
+ *                (see __add_missing_keys)
+ * - column 4:    we use the key to find the parent
+ *
+ * additional information that's available but not required to find the parent
+ * block might help in merging entries to gain some speed.
+ */
+
 static int __add_prelim_ref(struct list_head *head, u64 root_id,
-                           struct btrfs_key *key, int level, u64 parent,
-                           u64 wanted_disk_byte, int count)
+                           struct btrfs_key *key, int level,
+                           u64 parent, u64 wanted_disk_byte, int count)
 {
        struct __prelim_ref *ref;
 
@@ -49,10 +164,11 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
 
        ref->root_id = root_id;
        if (key)
-               ref->key = *key;
+               ref->key_for_search = *key;
        else
-               memset(&ref->key, 0, sizeof(ref->key));
+               memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
 
+       ref->inode_list = NULL;
        ref->level = level;
        ref->count = count;
        ref->parent = parent;
@@ -63,52 +179,75 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
 }
 
 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
-                               struct ulist *parents,
-                               struct extent_buffer *eb, int level,
-                               u64 wanted_objectid, u64 wanted_disk_byte)
+                               struct ulist *parents, int level,
+                               struct btrfs_key *key_for_search, u64 time_seq,
+                               u64 wanted_disk_byte,
+                               const u64 *extent_item_pos)
 {
-       int ret;
+       int ret = 0;
        int slot;
-       struct btrfs_file_extent_item *fi;
+       struct extent_buffer *eb;
        struct btrfs_key key;
+       struct btrfs_file_extent_item *fi;
+       struct extent_inode_elem *eie = NULL;
        u64 disk_byte;
 
-add_parent:
-       ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
-       if (ret < 0)
-               return ret;
-
-       if (level != 0)
+       if (level != 0) {
+               eb = path->nodes[level];
+               ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
+               if (ret < 0)
+                       return ret;
                return 0;
+       }
 
        /*
-        * if the current leaf is full with EXTENT_DATA items, we must
-        * check the next one if that holds a reference as well.
-        * ref->count cannot be used to skip this check.
-        * repeat this until we don't find any additional EXTENT_DATA items.
+        * We normally enter this function with the path already pointing to
+        * the first item to check. But sometimes, we may enter it with
+        * slot==nritems. In that case, go to the next leaf before we continue.
         */
-       while (1) {
-               ret = btrfs_next_leaf(root, path);
-               if (ret < 0)
-                       return ret;
-               if (ret)
-                       return 0;
+       if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
+               ret = btrfs_next_old_leaf(root, path, time_seq);
 
+       while (!ret) {
                eb = path->nodes[0];
-               for (slot = 0; slot < btrfs_header_nritems(eb); ++slot) {
-                       btrfs_item_key_to_cpu(eb, &key, slot);
-                       if (key.objectid != wanted_objectid ||
-                           key.type != BTRFS_EXTENT_DATA_KEY)
-                               return 0;
-                       fi = btrfs_item_ptr(eb, slot,
-                                               struct btrfs_file_extent_item);
-                       disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
-                       if (disk_byte == wanted_disk_byte)
-                               goto add_parent;
+               slot = path->slots[0];
+
+               btrfs_item_key_to_cpu(eb, &key, slot);
+
+               if (key.objectid != key_for_search->objectid ||
+                   key.type != BTRFS_EXTENT_DATA_KEY)
+                       break;
+
+               fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
+               disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
+
+               if (disk_byte == wanted_disk_byte) {
+                       eie = NULL;
+                       if (extent_item_pos) {
+                               ret = check_extent_in_eb(&key, eb, fi,
+                                               *extent_item_pos,
+                                               &eie);
+                               if (ret < 0)
+                                       break;
+                       }
+                       if (!ret) {
+                               ret = ulist_add(parents, eb->start,
+                                               (uintptr_t)eie, GFP_NOFS);
+                               if (ret < 0)
+                                       break;
+                               if (!extent_item_pos) {
+                                       ret = btrfs_next_old_leaf(root, path,
+                                                       time_seq);
+                                       continue;
+                               }
+                       }
                }
+               ret = btrfs_next_old_item(root, path, time_seq);
        }
 
-       return 0;
+       if (ret > 0)
+               ret = 0;
+       return ret;
 }
 
 /*
@@ -117,13 +256,14 @@ add_parent:
  */
 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
                                        int search_commit_root,
+                                       u64 time_seq,
                                        struct __prelim_ref *ref,
-                                       struct ulist *parents)
+                                       struct ulist *parents,
+                                       const u64 *extent_item_pos)
 {
        struct btrfs_path *path;
        struct btrfs_root *root;
        struct btrfs_key root_key;
-       struct btrfs_key key = {0};
        struct extent_buffer *eb;
        int ret = 0;
        int root_level;
@@ -143,44 +283,36 @@ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
                goto out;
        }
 
-       rcu_read_lock();
-       root_level = btrfs_header_level(root->node);
-       rcu_read_unlock();
+       root_level = btrfs_old_root_level(root, time_seq);
 
        if (root_level + 1 == level)
                goto out;
 
        path->lowest_level = level;
-       ret = btrfs_search_slot(NULL, root, &ref->key, path, 0, 0);
+       ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
        pr_debug("search slot in root %llu (level %d, ref count %d) returned "
                 "%d for key (%llu %u %llu)\n",
                 (unsigned long long)ref->root_id, level, ref->count, ret,
-                (unsigned long long)ref->key.objectid, ref->key.type,
-                (unsigned long long)ref->key.offset);
+                (unsigned long long)ref->key_for_search.objectid,
+                ref->key_for_search.type,
+                (unsigned long long)ref->key_for_search.offset);
        if (ret < 0)
                goto out;
 
        eb = path->nodes[level];
-       if (!eb) {
-               WARN_ON(1);
-               ret = 1;
-               goto out;
-       }
-
-       if (level == 0) {
-               if (ret == 1 && path->slots[0] >= btrfs_header_nritems(eb)) {
-                       ret = btrfs_next_leaf(root, path);
-                       if (ret)
-                               goto out;
-                       eb = path->nodes[0];
+       while (!eb) {
+               if (!level) {
+                       WARN_ON(1);
+                       ret = 1;
+                       goto out;
                }
-
-               btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
+               level--;
+               eb = path->nodes[level];
        }
 
-       /* the last two parameters will only be used for level == 0 */
-       ret = add_all_parents(root, path, parents, eb, level, key.objectid,
-                               ref->wanted_disk_byte);
+       ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
+                               time_seq, ref->wanted_disk_byte,
+                               extent_item_pos);
 out:
        btrfs_free_path(path);
        return ret;
@@ -190,8 +322,9 @@ out:
  * resolve all indirect backrefs from the list
  */
 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
-                                  int search_commit_root,
-                                  struct list_head *head)
+                                  int search_commit_root, u64 time_seq,
+                                  struct list_head *head,
+                                  const u64 *extent_item_pos)
 {
        int err;
        int ret = 0;
@@ -200,6 +333,7 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
        struct __prelim_ref *new_ref;
        struct ulist *parents;
        struct ulist_node *node;
+       struct ulist_iterator uiter;
 
        parents = ulist_alloc(GFP_NOFS);
        if (!parents)
@@ -216,7 +350,8 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
                if (ref->count == 0)
                        continue;
                err = __resolve_indirect_ref(fs_info, search_commit_root,
-                                            ref, parents);
+                                            time_seq, ref, parents,
+                                            extent_item_pos);
                if (err) {
                        if (ret == 0)
                                ret = err;
@@ -224,11 +359,14 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
                }
 
                /* we put the first parent into the ref at hand */
-               node = ulist_next(parents, NULL);
+               ULIST_ITER_INIT(&uiter);
+               node = ulist_next(parents, &uiter);
                ref->parent = node ? node->val : 0;
+               ref->inode_list = node ?
+                       (struct extent_inode_elem *)(uintptr_t)node->aux : 0;
 
                /* additional parents require new refs being added here */
-               while ((node = ulist_next(parents, node))) {
+               while ((node = ulist_next(parents, &uiter))) {
                        new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
                        if (!new_ref) {
                                ret = -ENOMEM;
@@ -236,6 +374,8 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
                        }
                        memcpy(new_ref, ref, sizeof(*ref));
                        new_ref->parent = node->val;
+                       new_ref->inode_list = (struct extent_inode_elem *)
+                                                       (uintptr_t)node->aux;
                        list_add(&new_ref->list, &ref->list);
                }
                ulist_reinit(parents);
@@ -245,10 +385,65 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
        return ret;
 }
 
+static inline int ref_for_same_block(struct __prelim_ref *ref1,
+                                    struct __prelim_ref *ref2)
+{
+       if (ref1->level != ref2->level)
+               return 0;
+       if (ref1->root_id != ref2->root_id)
+               return 0;
+       if (ref1->key_for_search.type != ref2->key_for_search.type)
+               return 0;
+       if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
+               return 0;
+       if (ref1->key_for_search.offset != ref2->key_for_search.offset)
+               return 0;
+       if (ref1->parent != ref2->parent)
+               return 0;
+
+       return 1;
+}
+
+/*
+ * read tree blocks and add keys where required.
+ */
+static int __add_missing_keys(struct btrfs_fs_info *fs_info,
+                             struct list_head *head)
+{
+       struct list_head *pos;
+       struct extent_buffer *eb;
+
+       list_for_each(pos, head) {
+               struct __prelim_ref *ref;
+               ref = list_entry(pos, struct __prelim_ref, list);
+
+               if (ref->parent)
+                       continue;
+               if (ref->key_for_search.type)
+                       continue;
+               BUG_ON(!ref->wanted_disk_byte);
+               eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
+                                    fs_info->tree_root->leafsize, 0);
+               BUG_ON(!eb);
+               btrfs_tree_read_lock(eb);
+               if (btrfs_header_level(eb) == 0)
+                       btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
+               else
+                       btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
+               btrfs_tree_read_unlock(eb);
+               free_extent_buffer(eb);
+       }
+       return 0;
+}
+
 /*
  * merge two lists of backrefs and adjust counts accordingly
  *
  * mode = 1: merge identical keys, if key is set
+ *    FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
+ *           additionally, we could even add a key range for the blocks we
+ *           looked into to merge even more (-> replace unresolved refs by those
+ *           having a parent).
  * mode = 2: merge identical parents
  */
 static int __merge_refs(struct list_head *head, int mode)
@@ -262,26 +457,36 @@ static int __merge_refs(struct list_head *head, int mode)
 
                ref1 = list_entry(pos1, struct __prelim_ref, list);
 
-               if (mode == 1 && ref1->key.type == 0)
-                       continue;
                for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
                     pos2 = n2, n2 = pos2->next) {
                        struct __prelim_ref *ref2;
+                       struct __prelim_ref *xchg;
+                       struct extent_inode_elem *eie;
 
                        ref2 = list_entry(pos2, struct __prelim_ref, list);
 
                        if (mode == 1) {
-                               if (memcmp(&ref1->key, &ref2->key,
-                                          sizeof(ref1->key)) ||
-                                   ref1->level != ref2->level ||
-                                   ref1->root_id != ref2->root_id)
+                               if (!ref_for_same_block(ref1, ref2))
                                        continue;
-                               ref1->count += ref2->count;
+                               if (!ref1->parent && ref2->parent) {
+                                       xchg = ref1;
+                                       ref1 = ref2;
+                                       ref2 = xchg;
+                               }
                        } else {
                                if (ref1->parent != ref2->parent)
                                        continue;
-                               ref1->count += ref2->count;
                        }
+
+                       eie = ref1->inode_list;
+                       while (eie && eie->next)
+                               eie = eie->next;
+                       if (eie)
+                               eie->next = ref2->inode_list;
+                       else
+                               ref1->inode_list = ref2->inode_list;
+                       ref1->count += ref2->count;
+
                        list_del(&ref2->list);
                        kfree(ref2);
                }
@@ -295,16 +500,17 @@ static int __merge_refs(struct list_head *head, int mode)
  * smaller or equal that seq to the list
  */
 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
-                             struct btrfs_key *info_key,
                              struct list_head *prefs)
 {
        struct btrfs_delayed_extent_op *extent_op = head->extent_op;
        struct rb_node *n = &head->node.rb_node;
+       struct btrfs_key key;
+       struct btrfs_key op_key = {0};
        int sgn;
        int ret = 0;
 
        if (extent_op && extent_op->update_key)
-               btrfs_disk_key_to_cpu(info_key, &extent_op->key);
+               btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
 
        while ((n = rb_prev(n))) {
                struct btrfs_delayed_ref_node *node;
@@ -336,7 +542,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
                        struct btrfs_delayed_tree_ref *ref;
 
                        ref = btrfs_delayed_node_to_tree_ref(node);
-                       ret = __add_prelim_ref(prefs, ref->root, info_key,
+                       ret = __add_prelim_ref(prefs, ref->root, &op_key,
                                               ref->level + 1, 0, node->bytenr,
                                               node->ref_mod * sgn);
                        break;
@@ -345,7 +551,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
                        struct btrfs_delayed_tree_ref *ref;
 
                        ref = btrfs_delayed_node_to_tree_ref(node);
-                       ret = __add_prelim_ref(prefs, ref->root, info_key,
+                       ret = __add_prelim_ref(prefs, ref->root, NULL,
                                               ref->level + 1, ref->parent,
                                               node->bytenr,
                                               node->ref_mod * sgn);
@@ -353,8 +559,6 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
                }
                case BTRFS_EXTENT_DATA_REF_KEY: {
                        struct btrfs_delayed_data_ref *ref;
-                       struct btrfs_key key;
-
                        ref = btrfs_delayed_node_to_data_ref(node);
 
                        key.objectid = ref->objectid;
@@ -367,7 +571,6 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
                }
                case BTRFS_SHARED_DATA_REF_KEY: {
                        struct btrfs_delayed_data_ref *ref;
-                       struct btrfs_key key;
 
                        ref = btrfs_delayed_node_to_data_ref(node);
 
@@ -393,8 +596,7 @@ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
  */
 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
                             struct btrfs_path *path, u64 bytenr,
-                            struct btrfs_key *info_key, int *info_level,
-                            struct list_head *prefs)
+                            int *info_level, struct list_head *prefs)
 {
        int ret = 0;
        int slot;
@@ -410,7 +612,7 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
         * enumerate all inline refs
         */
        leaf = path->nodes[0];
-       slot = path->slots[0] - 1;
+       slot = path->slots[0];
 
        item_size = btrfs_item_size_nr(leaf, slot);
        BUG_ON(item_size < sizeof(*ei));
@@ -423,12 +625,9 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
 
        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
                struct btrfs_tree_block_info *info;
-               struct btrfs_disk_key disk_key;
 
                info = (struct btrfs_tree_block_info *)ptr;
                *info_level = btrfs_tree_block_level(leaf, info);
-               btrfs_tree_block_key(leaf, info, &disk_key);
-               btrfs_disk_key_to_cpu(info_key, &disk_key);
                ptr += sizeof(struct btrfs_tree_block_info);
                BUG_ON(ptr > end);
        } else {
@@ -446,7 +645,7 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
 
                switch (type) {
                case BTRFS_SHARED_BLOCK_REF_KEY:
-                       ret = __add_prelim_ref(prefs, 0, info_key,
+                       ret = __add_prelim_ref(prefs, 0, NULL,
                                                *info_level + 1, offset,
                                                bytenr, 1);
                        break;
@@ -461,8 +660,9 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
                        break;
                }
                case BTRFS_TREE_BLOCK_REF_KEY:
-                       ret = __add_prelim_ref(prefs, offset, info_key,
-                                              *info_level + 1, 0, bytenr, 1);
+                       ret = __add_prelim_ref(prefs, offset, NULL,
+                                              *info_level + 1, 0,
+                                              bytenr, 1);
                        break;
                case BTRFS_EXTENT_DATA_REF_KEY: {
                        struct btrfs_extent_data_ref *dref;
@@ -476,8 +676,8 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
                        key.type = BTRFS_EXTENT_DATA_KEY;
                        key.offset = btrfs_extent_data_ref_offset(leaf, dref);
                        root = btrfs_extent_data_ref_root(leaf, dref);
-                       ret = __add_prelim_ref(prefs, root, &key, 0, 0, bytenr,
-                                               count);
+                       ret = __add_prelim_ref(prefs, root, &key, 0, 0,
+                                              bytenr, count);
                        break;
                }
                default:
@@ -495,8 +695,7 @@ static int __add_inline_refs(struct btrfs_fs_info *fs_info,
  */
 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
                            struct btrfs_path *path, u64 bytenr,
-                           struct btrfs_key *info_key, int info_level,
-                           struct list_head *prefs)
+                           int info_level, struct list_head *prefs)
 {
        struct btrfs_root *extent_root = fs_info->extent_root;
        int ret;
@@ -526,7 +725,7 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
 
                switch (key.type) {
                case BTRFS_SHARED_BLOCK_REF_KEY:
-                       ret = __add_prelim_ref(prefs, 0, info_key,
+                       ret = __add_prelim_ref(prefs, 0, NULL,
                                                info_level + 1, key.offset,
                                                bytenr, 1);
                        break;
@@ -542,8 +741,9 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
                        break;
                }
                case BTRFS_TREE_BLOCK_REF_KEY:
-                       ret = __add_prelim_ref(prefs, key.offset, info_key,
-                                               info_level + 1, 0, bytenr, 1);
+                       ret = __add_prelim_ref(prefs, key.offset, NULL,
+                                              info_level + 1, 0,
+                                              bytenr, 1);
                        break;
                case BTRFS_EXTENT_DATA_REF_KEY: {
                        struct btrfs_extent_data_ref *dref;
@@ -559,7 +759,7 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
                        key.offset = btrfs_extent_data_ref_offset(leaf, dref);
                        root = btrfs_extent_data_ref_root(leaf, dref);
                        ret = __add_prelim_ref(prefs, root, &key, 0, 0,
-                                               bytenr, count);
+                                              bytenr, count);
                        break;
                }
                default:
@@ -581,11 +781,11 @@ static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
  */
 static int find_parent_nodes(struct btrfs_trans_handle *trans,
                             struct btrfs_fs_info *fs_info, u64 bytenr,
-                            u64 seq, struct ulist *refs, struct ulist *roots)
+                            u64 time_seq, struct ulist *refs,
+                            struct ulist *roots, const u64 *extent_item_pos)
 {
        struct btrfs_key key;
        struct btrfs_path *path;
-       struct btrfs_key info_key = { 0 };
        struct btrfs_delayed_ref_root *delayed_refs = NULL;
        struct btrfs_delayed_ref_head *head;
        int info_level = 0;
@@ -644,8 +844,9 @@ again:
                                btrfs_put_delayed_ref(&head->node);
                                goto again;
                        }
-                       ret = __add_delayed_refs(head, seq, &info_key,
+                       ret = __add_delayed_refs(head, time_seq,
                                                 &prefs_delayed);
+                       mutex_unlock(&head->mutex);
                        if (ret) {
                                spin_unlock(&delayed_refs->lock);
                                goto out;
@@ -658,16 +859,17 @@ again:
                struct extent_buffer *leaf;
                int slot;
 
+               path->slots[0]--;
                leaf = path->nodes[0];
-               slot = path->slots[0] - 1;
+               slot = path->slots[0];
                btrfs_item_key_to_cpu(leaf, &key, slot);
                if (key.objectid == bytenr &&
                    key.type == BTRFS_EXTENT_ITEM_KEY) {
                        ret = __add_inline_refs(fs_info, path, bytenr,
-                                               &info_key, &info_level, &prefs);
+                                               &info_level, &prefs);
                        if (ret)
                                goto out;
-                       ret = __add_keyed_refs(fs_info, path, bytenr, &info_key,
+                       ret = __add_keyed_refs(fs_info, path, bytenr,
                                               info_level, &prefs);
                        if (ret)
                                goto out;
@@ -675,21 +877,18 @@ again:
        }
        btrfs_release_path(path);
 
-       /*
-        * when adding the delayed refs above, the info_key might not have
-        * been known yet. Go over the list and replace the missing keys
-        */
-       list_for_each_entry(ref, &prefs_delayed, list) {
-               if ((ref->key.offset | ref->key.type | ref->key.objectid) == 0)
-                       memcpy(&ref->key, &info_key, sizeof(ref->key));
-       }
        list_splice_init(&prefs_delayed, &prefs);
 
+       ret = __add_missing_keys(fs_info, &prefs);
+       if (ret)
+               goto out;
+
        ret = __merge_refs(&prefs, 1);
        if (ret)
                goto out;
 
-       ret = __resolve_indirect_refs(fs_info, search_commit_root, &prefs);
+       ret = __resolve_indirect_refs(fs_info, search_commit_root, time_seq,
+                                     &prefs, extent_item_pos);
        if (ret)
                goto out;
 
@@ -700,23 +899,46 @@ again:
        while (!list_empty(&prefs)) {
                ref = list_first_entry(&prefs, struct __prelim_ref, list);
                list_del(&ref->list);
-               if (ref->count < 0)
-                       WARN_ON(1);
+               WARN_ON(ref->count < 0);
                if (ref->count && ref->root_id && ref->parent == 0) {
                        /* no parent == root of tree */
                        ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
                        BUG_ON(ret < 0);
                }
                if (ref->count && ref->parent) {
-                       ret = ulist_add(refs, ref->parent, 0, GFP_NOFS);
+                       struct extent_inode_elem *eie = NULL;
+                       if (extent_item_pos && !ref->inode_list) {
+                               u32 bsz;
+                               struct extent_buffer *eb;
+                               bsz = btrfs_level_size(fs_info->extent_root,
+                                                       info_level);
+                               eb = read_tree_block(fs_info->extent_root,
+                                                          ref->parent, bsz, 0);
+                               BUG_ON(!eb);
+                               ret = find_extent_in_eb(eb, bytenr,
+                                                       *extent_item_pos, &eie);
+                               ref->inode_list = eie;
+                               free_extent_buffer(eb);
+                       }
+                       ret = ulist_add_merge(refs, ref->parent,
+                                             (uintptr_t)ref->inode_list,
+                                             (u64 *)&eie, GFP_NOFS);
+                       if (!ret && extent_item_pos) {
+                               /*
+                                * we've recorded that parent, so we must extend
+                                * its inode list here
+                                */
+                               BUG_ON(!eie);
+                               while (eie->next)
+                                       eie = eie->next;
+                               eie->next = ref->inode_list;
+                       }
                        BUG_ON(ret < 0);
                }
                kfree(ref);
        }
 
 out:
-       if (head)
-               mutex_unlock(&head->mutex);
        btrfs_free_path(path);
        while (!list_empty(&prefs)) {
                ref = list_first_entry(&prefs, struct __prelim_ref, list);
@@ -733,6 +955,28 @@ out:
        return ret;
 }
 
+static void free_leaf_list(struct ulist *blocks)
+{
+       struct ulist_node *node = NULL;
+       struct extent_inode_elem *eie;
+       struct extent_inode_elem *eie_next;
+       struct ulist_iterator uiter;
+
+       ULIST_ITER_INIT(&uiter);
+       while ((node = ulist_next(blocks, &uiter))) {
+               if (!node->aux)
+                       continue;
+               eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
+               for (; eie; eie = eie_next) {
+                       eie_next = eie->next;
+                       kfree(eie);
+               }
+               node->aux = 0;
+       }
+
+       ulist_free(blocks);
+}
+
 /*
  * Finds all leafs with a reference to the specified combination of bytenr and
  * offset. key_list_head will point to a list of corresponding keys (caller must
@@ -743,7 +987,8 @@ out:
  */
 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
                                struct btrfs_fs_info *fs_info, u64 bytenr,
-                               u64 num_bytes, u64 seq, struct ulist **leafs)
+                               u64 time_seq, struct ulist **leafs,
+                               const u64 *extent_item_pos)
 {
        struct ulist *tmp;
        int ret;
@@ -757,11 +1002,12 @@ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
                return -ENOMEM;
        }
 
-       ret = find_parent_nodes(trans, fs_info, bytenr, seq, *leafs, tmp);
+       ret = find_parent_nodes(trans, fs_info, bytenr,
+                               time_seq, *leafs, tmp, extent_item_pos);
        ulist_free(tmp);
 
        if (ret < 0 && ret != -ENOENT) {
-               ulist_free(*leafs);
+               free_leaf_list(*leafs);
                return ret;
        }
 
@@ -783,10 +1029,11 @@ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
  */
 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
                                struct btrfs_fs_info *fs_info, u64 bytenr,
-                               u64 num_bytes, u64 seq, struct ulist **roots)
+                               u64 time_seq, struct ulist **roots)
 {
        struct ulist *tmp;
        struct ulist_node *node = NULL;
+       struct ulist_iterator uiter;
        int ret;
 
        tmp = ulist_alloc(GFP_NOFS);
@@ -798,15 +1045,16 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
                return -ENOMEM;
        }
 
+       ULIST_ITER_INIT(&uiter);
        while (1) {
-               ret = find_parent_nodes(trans, fs_info, bytenr, seq,
-                                       tmp, *roots);
+               ret = find_parent_nodes(trans, fs_info, bytenr,
+                                       time_seq, tmp, *roots, NULL);
                if (ret < 0 && ret != -ENOENT) {
                        ulist_free(tmp);
                        ulist_free(*roots);
                        return ret;
                }
-               node = ulist_next(tmp, node);
+               node = ulist_next(tmp, &uiter);
                if (!node)
                        break;
                bytenr = node->val;
@@ -867,49 +1115,107 @@ static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
                                found_key);
 }
 
-/*
- * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
- * of the path are separated by '/' and the path is guaranteed to be
- * 0-terminated. the path is only given within the current file system.
- * Therefore, it never starts with a '/'. the caller is responsible to provide
- * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
- * the start point of the resulting string is returned. this pointer is within
- * dest, normally.
- * in case the path buffer would overflow, the pointer is decremented further
- * as if output was written to the buffer, though no more output is actually
- * generated. that way, the caller can determine how much space would be
- * required for the path to fit into the buffer. in that case, the returned
- * value will be smaller than dest. callers must check this!
- */
-static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
-                               struct btrfs_inode_ref *iref,
-                               struct extent_buffer *eb_in, u64 parent,
-                               char *dest, u32 size)
+int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
+                         u64 start_off, struct btrfs_path *path,
+                         struct btrfs_inode_extref **ret_extref,
+                         u64 *found_off)
+{
+       int ret, slot;
+       struct btrfs_key key;
+       struct btrfs_key found_key;
+       struct btrfs_inode_extref *extref;
+       struct extent_buffer *leaf;
+       unsigned long ptr;
+
+       key.objectid = inode_objectid;
+       btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
+       key.offset = start_off;
+
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret < 0)
+               return ret;
+
+       while (1) {
+               leaf = path->nodes[0];
+               slot = path->slots[0];
+               if (slot >= btrfs_header_nritems(leaf)) {
+                       /*
+                        * If the item at offset is not found,
+                        * btrfs_search_slot will point us to the slot
+                        * where it should be inserted. In our case
+                        * that will be the slot directly before the
+                        * next INODE_REF_KEY_V2 item. In the case
+                        * that we're pointing to the last slot in a
+                        * leaf, we must move one leaf over.
+                        */
+                       ret = btrfs_next_leaf(root, path);
+                       if (ret) {
+                               if (ret >= 1)
+                                       ret = -ENOENT;
+                               break;
+                       }
+                       continue;
+               }
+
+               btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+               /*
+                * Check that we're still looking at an extended ref key for
+                * this particular objectid. If we have different
+                * objectid or type then there are no more to be found
+                * in the tree and we can exit.
+                */
+               ret = -ENOENT;
+               if (found_key.objectid != inode_objectid)
+                       break;
+               if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
+                       break;
+
+               ret = 0;
+               ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+               extref = (struct btrfs_inode_extref *)ptr;
+               *ret_extref = extref;
+               if (found_off)
+                       *found_off = found_key.offset;
+               break;
+       }
+
+       return ret;
+}
+
+char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
+                       u32 name_len, unsigned long name_off,
+                       struct extent_buffer *eb_in, u64 parent,
+                       char *dest, u32 size)
 {
-       u32 len;
        int slot;
        u64 next_inum;
        int ret;
-       s64 bytes_left = size - 1;
+       s64 bytes_left = ((s64)size) - 1;
        struct extent_buffer *eb = eb_in;
        struct btrfs_key found_key;
+       int leave_spinning = path->leave_spinning;
+       struct btrfs_inode_ref *iref;
 
        if (bytes_left >= 0)
                dest[bytes_left] = '\0';
 
+       path->leave_spinning = 1;
        while (1) {
-               len = btrfs_inode_ref_name_len(eb, iref);
-               bytes_left -= len;
+               bytes_left -= name_len;
                if (bytes_left >= 0)
                        read_extent_buffer(eb, dest + bytes_left,
-                                               (unsigned long)(iref + 1), len);
-               if (eb != eb_in)
+                                          name_off, name_len);
+               if (eb != eb_in) {
+                       btrfs_tree_read_unlock_blocking(eb);
                        free_extent_buffer(eb);
+               }
                ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
                if (ret > 0)
                        ret = -ENOENT;
                if (ret)
                        break;
+
                next_inum = found_key.offset;
 
                /* regular exit ahead */
@@ -919,11 +1225,17 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
                slot = path->slots[0];
                eb = path->nodes[0];
                /* make sure we can use eb after releasing the path */
-               if (eb != eb_in)
+               if (eb != eb_in) {
                        atomic_inc(&eb->refs);
+                       btrfs_tree_read_lock(eb);
+                       btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
+               }
                btrfs_release_path(path);
-
                iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
+
+               name_len = btrfs_inode_ref_name_len(eb, iref);
+               name_off = (unsigned long)(iref + 1);
+
                parent = next_inum;
                --bytes_left;
                if (bytes_left >= 0)
@@ -931,6 +1243,7 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
        }
 
        btrfs_release_path(path);
+       path->leave_spinning = leave_spinning;
 
        if (ret)
                return ERR_PTR(ret);
@@ -939,12 +1252,39 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
 }
 
 /*
+ * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements
+ * of the path are separated by '/' and the path is guaranteed to be
+ * 0-terminated. the path is only given within the current file system.
+ * Therefore, it never starts with a '/'. the caller is responsible to provide
+ * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
+ * the start point of the resulting string is returned. this pointer is within
+ * dest, normally.
+ * in case the path buffer would overflow, the pointer is decremented further
+ * as if output was written to the buffer, though no more output is actually
+ * generated. that way, the caller can determine how much space would be
+ * required for the path to fit into the buffer. in that case, the returned
+ * value will be smaller than dest. callers must check this!
+ */
+char *btrfs_iref_to_path(struct btrfs_root *fs_root,
+                        struct btrfs_path *path,
+                        struct btrfs_inode_ref *iref,
+                        struct extent_buffer *eb_in, u64 parent,
+                        char *dest, u32 size)
+{
+       return btrfs_ref_to_path(fs_root, path,
+                                btrfs_inode_ref_name_len(eb_in, iref),
+                                (unsigned long)(iref + 1),
+                                eb_in, parent, dest, size);
+}
+
+/*
  * this makes the path point to (logical EXTENT_ITEM *)
  * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
  * tree blocks and <0 on error.
  */
 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
-                       struct btrfs_path *path, struct btrfs_key *found_key)
+                       struct btrfs_path *path, struct btrfs_key *found_key,
+                       u64 *flags_ret)
 {
        int ret;
        u64 flags;
@@ -988,10 +1328,17 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
                 (unsigned long long)found_key->objectid,
                 (unsigned long long)found_key->offset,
                 (unsigned long long)flags, item_size);
-       if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
-               return BTRFS_EXTENT_FLAG_TREE_BLOCK;
-       if (flags & BTRFS_EXTENT_FLAG_DATA)
-               return BTRFS_EXTENT_FLAG_DATA;
+
+       WARN_ON(!flags_ret);
+       if (flags_ret) {
+               if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+                       *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
+               else if (flags & BTRFS_EXTENT_FLAG_DATA)
+                       *flags_ret = BTRFS_EXTENT_FLAG_DATA;
+               else
+                       BUG_ON(1);
+               return 0;
+       }
 
        return -EIO;
 }
@@ -1084,67 +1431,25 @@ int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
        return 0;
 }
 
-static int iterate_leaf_refs(struct btrfs_fs_info *fs_info, u64 logical,
-                               u64 orig_extent_item_objectid,
-                               u64 extent_item_pos, u64 root,
+static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
+                               u64 root, u64 extent_item_objectid,
                                iterate_extent_inodes_t *iterate, void *ctx)
 {
-       u64 disk_byte;
-       struct btrfs_key key;
-       struct btrfs_file_extent_item *fi;
-       struct extent_buffer *eb;
-       int slot;
-       int nritems;
+       struct extent_inode_elem *eie;
        int ret = 0;
-       int extent_type;
-       u64 data_offset;
-       u64 data_len;
-
-       eb = read_tree_block(fs_info->tree_root, logical,
-                               fs_info->tree_root->leafsize, 0);
-       if (!eb)
-               return -EIO;
-
-       /*
-        * from the shared data ref, we only have the leaf but we need
-        * the key. thus, we must look into all items and see that we
-        * find one (some) with a reference to our extent item.
-        */
-       nritems = btrfs_header_nritems(eb);
-       for (slot = 0; slot < nritems; ++slot) {
-               btrfs_item_key_to_cpu(eb, &key, slot);
-               if (key.type != BTRFS_EXTENT_DATA_KEY)
-                       continue;
-               fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
-               extent_type = btrfs_file_extent_type(eb, fi);
-               if (extent_type == BTRFS_FILE_EXTENT_INLINE)
-                       continue;
-               /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
-               disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
-               if (disk_byte != orig_extent_item_objectid)
-                       continue;
-
-               data_offset = btrfs_file_extent_offset(eb, fi);
-               data_len = btrfs_file_extent_num_bytes(eb, fi);
-
-               if (extent_item_pos < data_offset ||
-                   extent_item_pos >= data_offset + data_len)
-                       continue;
 
+       for (eie = inode_list; eie; eie = eie->next) {
                pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
-                               "root %llu\n", orig_extent_item_objectid,
-                               key.objectid, key.offset, root);
-               ret = iterate(key.objectid,
-                               key.offset + (extent_item_pos - data_offset),
-                               root, ctx);
+                        "root %llu\n", extent_item_objectid,
+                        eie->inum, eie->offset, root);
+               ret = iterate(eie->inum, eie->offset, root, ctx);
                if (ret) {
-                       pr_debug("stopping iteration because ret=%d\n", ret);
+                       pr_debug("stopping iteration for %llu due to ret=%d\n",
+                                extent_item_objectid, ret);
                        break;
                }
        }
 
-       free_extent_buffer(eb);
-
        return ret;
 }
 
@@ -1166,8 +1471,9 @@ int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
        struct ulist *roots = NULL;
        struct ulist_node *ref_node = NULL;
        struct ulist_node *root_node = NULL;
-       struct seq_list seq_elem;
-       struct btrfs_delayed_ref_root *delayed_refs = NULL;
+       struct seq_list tree_mod_seq_elem = {};
+       struct ulist_iterator ref_uiter;
+       struct ulist_iterator root_uiter;
 
        pr_debug("resolving all inodes for extent %llu\n",
                        extent_item_objectid);
@@ -1178,40 +1484,41 @@ int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
                trans = btrfs_join_transaction(fs_info->extent_root);
                if (IS_ERR(trans))
                        return PTR_ERR(trans);
-
-               delayed_refs = &trans->transaction->delayed_refs;
-               spin_lock(&delayed_refs->lock);
-               btrfs_get_delayed_seq(delayed_refs, &seq_elem);
-               spin_unlock(&delayed_refs->lock);
+               btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
        }
 
        ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
-                                  extent_item_pos, seq_elem.seq,
-                                  &refs);
-
+                                  tree_mod_seq_elem.seq, &refs,
+                                  &extent_item_pos);
        if (ret)
                goto out;
 
-       while (!ret && (ref_node = ulist_next(refs, ref_node))) {
-               ret = btrfs_find_all_roots(trans, fs_info, ref_node->val, -1,
-                                               seq_elem.seq, &roots);
+       ULIST_ITER_INIT(&ref_uiter);
+       while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
+               ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
+                                          tree_mod_seq_elem.seq, &roots);
                if (ret)
                        break;
-               while (!ret && (root_node = ulist_next(roots, root_node))) {
-                       pr_debug("root %llu references leaf %llu\n",
-                                       root_node->val, ref_node->val);
-                       ret = iterate_leaf_refs(fs_info, ref_node->val,
+               ULIST_ITER_INIT(&root_uiter);
+               while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
+                       pr_debug("root %llu references leaf %llu, data list "
+                                "%#llx\n", root_node->val, ref_node->val,
+                                (long long)ref_node->aux);
+                       ret = iterate_leaf_refs((struct extent_inode_elem *)
+                                               (uintptr_t)ref_node->aux,
+                                               root_node->val,
                                                extent_item_objectid,
-                                               extent_item_pos, root_node->val,
                                                iterate, ctx);
                }
+               ulist_free(roots);
+               roots = NULL;
        }
 
-       ulist_free(refs);
+       free_leaf_list(refs);
        ulist_free(roots);
 out:
        if (!search_commit_root) {
-               btrfs_put_delayed_seq(delayed_refs, &seq_elem);
+               btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
                btrfs_end_transaction(trans, fs_info->extent_root);
        }
 
@@ -1224,16 +1531,16 @@ int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
 {
        int ret;
        u64 extent_item_pos;
+       u64 flags = 0;
        struct btrfs_key found_key;
        int search_commit_root = path->search_commit_root;
 
-       ret = extent_from_logical(fs_info, logical, path,
-                                       &found_key);
+       ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
        btrfs_release_path(path);
-       if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
-               ret = -EINVAL;
        if (ret < 0)
                return ret;
+       if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+               return -EINVAL;
 
        extent_item_pos = logical - found_key.objectid;
        ret = iterate_extent_inodes(fs_info, found_key.objectid,
@@ -1243,9 +1550,12 @@ int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
        return ret;
 }
 
-static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
-                               struct btrfs_path *path,
-                               iterate_irefs_t *iterate, void *ctx)
+typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
+                             struct extent_buffer *eb, void *ctx);
+
+static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
+                             struct btrfs_path *path,
+                             iterate_irefs_t *iterate, void *ctx)
 {
        int ret = 0;
        int slot;
@@ -1260,8 +1570,9 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
        struct btrfs_key found_key;
 
        while (!ret) {
+               path->leave_spinning = 1;
                ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
-                                       &found_key);
+                                    &found_key);
                if (ret < 0)
                        break;
                if (ret) {
@@ -1275,6 +1586,8 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
                eb = path->nodes[0];
                /* make sure we can use eb after releasing the path */
                atomic_inc(&eb->refs);
+               btrfs_tree_read_lock(eb);
+               btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
                btrfs_release_path(path);
 
                item = btrfs_item_nr(eb, slot);
@@ -1287,12 +1600,14 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
                                 "tree %llu\n", cur,
                                 (unsigned long long)found_key.objectid,
                                 (unsigned long long)fs_root->objectid);
-                       ret = iterate(parent, iref, eb, ctx);
+                       ret = iterate(parent, name_len,
+                                     (unsigned long)(iref + 1), eb, ctx);
                        if (ret)
                                break;
                        len = sizeof(*iref) + name_len;
                        iref = (struct btrfs_inode_ref *)((char *)iref + len);
                }
+               btrfs_tree_read_unlock_blocking(eb);
                free_extent_buffer(eb);
        }
 
@@ -1301,12 +1616,98 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
        return ret;
 }
 
+static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
+                                struct btrfs_path *path,
+                                iterate_irefs_t *iterate, void *ctx)
+{
+       int ret;
+       int slot;
+       u64 offset = 0;
+       u64 parent;
+       int found = 0;
+       struct extent_buffer *eb;
+       struct btrfs_inode_extref *extref;
+       struct extent_buffer *leaf;
+       u32 item_size;
+       u32 cur_offset;
+       unsigned long ptr;
+
+       while (1) {
+               ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
+                                           &offset);
+               if (ret < 0)
+                       break;
+               if (ret) {
+                       ret = found ? 0 : -ENOENT;
+                       break;
+               }
+               ++found;
+
+               slot = path->slots[0];
+               eb = path->nodes[0];
+               /* make sure we can use eb after releasing the path */
+               atomic_inc(&eb->refs);
+
+               btrfs_tree_read_lock(eb);
+               btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
+               btrfs_release_path(path);
+
+               leaf = path->nodes[0];
+               item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+               ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+               cur_offset = 0;
+
+               while (cur_offset < item_size) {
+                       u32 name_len;
+
+                       extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
+                       parent = btrfs_inode_extref_parent(eb, extref);
+                       name_len = btrfs_inode_extref_name_len(eb, extref);
+                       ret = iterate(parent, name_len,
+                                     (unsigned long)&extref->name, eb, ctx);
+                       if (ret)
+                               break;
+
+                       cur_offset += btrfs_inode_extref_name_len(leaf, extref);
+                       cur_offset += sizeof(*extref);
+               }
+               btrfs_tree_read_unlock_blocking(eb);
+               free_extent_buffer(eb);
+
+               offset++;
+       }
+
+       btrfs_release_path(path);
+
+       return ret;
+}
+
+static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
+                        struct btrfs_path *path, iterate_irefs_t *iterate,
+                        void *ctx)
+{
+       int ret;
+       int found_refs = 0;
+
+       ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
+       if (!ret)
+               ++found_refs;
+       else if (ret != -ENOENT)
+               return ret;
+
+       ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
+       if (ret == -ENOENT && found_refs)
+               return 0;
+
+       return ret;
+}
+
 /*
  * returns 0 if the path could be dumped (probably truncated)
  * returns <0 in case of an error
  */
-static int inode_to_path(u64 inum, struct btrfs_inode_ref *iref,
-                               struct extent_buffer *eb, void *ctx)
+static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
+                        struct extent_buffer *eb, void *ctx)
 {
        struct inode_fs_paths *ipath = ctx;
        char *fspath;
@@ -1319,20 +1720,16 @@ static int inode_to_path(u64 inum, struct btrfs_inode_ref *iref,
                                        ipath->fspath->bytes_left - s_ptr : 0;
 
        fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
-       fspath = iref_to_path(ipath->fs_root, ipath->btrfs_path, iref, eb,
-                               inum, fspath_min, bytes_left);
+       fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
+                                  name_off, eb, inum, fspath_min, bytes_left);
        if (IS_ERR(fspath))
                return PTR_ERR(fspath);
 
        if (fspath > fspath_min) {
-               pr_debug("path resolved: %s\n", fspath);
                ipath->fspath->val[i] = (u64)(unsigned long)fspath;
                ++ipath->fspath->elem_cnt;
                ipath->fspath->bytes_left = fspath - fspath_min;
        } else {
-               pr_debug("missed path, not enough space. missing bytes: %lu, "
-                        "constructed so far: %s\n",
-                        (unsigned long)(fspath_min - fspath), fspath_min);
                ++ipath->fspath->elem_missed;
                ipath->fspath->bytes_missing += fspath_min - fspath;
                ipath->fspath->bytes_left = 0;
@@ -1354,7 +1751,7 @@ static int inode_to_path(u64 inum, struct btrfs_inode_ref *iref,
 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
 {
        return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
-                               inode_to_path, ipath);
+                            inode_to_path, ipath);
 }
 
 struct btrfs_data_container *init_data_container(u32 total_bytes)
@@ -1363,7 +1760,7 @@ struct btrfs_data_container *init_data_container(u32 total_bytes)
        size_t alloc_bytes;
 
        alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
-       data = kmalloc(alloc_bytes, GFP_NOFS);
+       data = vmalloc(alloc_bytes);
        if (!data)
                return ERR_PTR(-ENOMEM);
 
@@ -1414,6 +1811,6 @@ void free_ipath(struct inode_fs_paths *ipath)
 {
        if (!ipath)
                return;
-       kfree(ipath->fspath);
+       vfree(ipath->fspath);
        kfree(ipath);
 }