Btrfs: add the ability to cache a pointer into the eb

[platform/kernel/linux-starfive.git] / fs / btrfs / ctree.c

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 0639a55..8af24da 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -156,10 +156,23 @@ struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 {
        struct extent_buffer *eb;
 
-       rcu_read_lock();
-       eb = rcu_dereference(root->node);
-       extent_buffer_get(eb);
-       rcu_read_unlock();
+       while (1) {
+               rcu_read_lock();
+               eb = rcu_dereference(root->node);
+
+               /*
+                * RCU really hurts here, we could free up the root node because
+                * it was cow'ed but we may not get the new root node yet so do
+                * the inc_not_zero dance and if it doesn't work then
+                * synchronize_rcu and try again.
+                */
+               if (atomic_inc_not_zero(&eb->refs)) {
+                       rcu_read_unlock();
+                       break;
+               }
+               rcu_read_unlock();
+               synchronize_rcu();
+       }
        return eb;
 }
 
@@ -504,7 +517,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
        }
        if (unlock_orig)
                btrfs_tree_unlock(buf);
-       free_extent_buffer(buf);
+       free_extent_buffer_stale(buf);
        btrfs_mark_buffer_dirty(cow);
        *cow_ret = cow;
        return 0;
@@ -959,7 +972,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                root_sub_used(root, mid->len);
                btrfs_free_tree_block(trans, root, mid, 0, 1, 0);
                /* once for the root ptr */
-               free_extent_buffer(mid);
+               free_extent_buffer_stale(mid);
                return 0;
        }
        if (btrfs_header_nritems(mid) >
@@ -1016,7 +1029,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                                ret = wret;
                        root_sub_used(root, right->len);
                        btrfs_free_tree_block(trans, root, right, 0, 1, 0);
-                       free_extent_buffer(right);
+                       free_extent_buffer_stale(right);
                        right = NULL;
                } else {
                        struct btrfs_disk_key right_key;
@@ -1056,7 +1069,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                        ret = wret;
                root_sub_used(root, mid->len);
                btrfs_free_tree_block(trans, root, mid, 0, 1, 0);
-               free_extent_buffer(mid);
+               free_extent_buffer_stale(mid);
                mid = NULL;
        } else {
                /* update the parent key to reflect our changes */
@@ -2320,6 +2333,7 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
 {
        struct extent_buffer *left = path->nodes[0];
        struct extent_buffer *upper = path->nodes[1];
+       struct btrfs_map_token token;
        struct btrfs_disk_key disk_key;
        int slot;
        u32 i;
@@ -2331,6 +2345,8 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
        u32 data_end;
        u32 this_item_size;
 
+       btrfs_init_map_token(&token);
+
        if (empty)
                nr = 0;
        else
@@ -2408,8 +2424,8 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
        push_space = BTRFS_LEAF_DATA_SIZE(root);
        for (i = 0; i < right_nritems; i++) {
                item = btrfs_item_nr(right, i);
-               push_space -= btrfs_item_size(right, item);
-               btrfs_set_item_offset(right, item, push_space);
+               push_space -= btrfs_token_item_size(right, item, &token);
+               btrfs_set_token_item_offset(right, item, push_space, &token);
        }
 
        left_nritems -= push_items;
@@ -2540,6 +2556,9 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
        int wret;
        u32 this_item_size;
        u32 old_left_item_size;
+       struct btrfs_map_token token;
+
+       btrfs_init_map_token(&token);
 
        if (empty)
                nr = min(right_nritems, max_slot);
@@ -2600,9 +2619,10 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
 
                item = btrfs_item_nr(left, i);
 
-               ioff = btrfs_item_offset(left, item);
-               btrfs_set_item_offset(left, item,
-                     ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
+               ioff = btrfs_token_item_offset(left, item, &token);
+               btrfs_set_token_item_offset(left, item,
+                     ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
+                     &token);
        }
        btrfs_set_header_nritems(left, old_left_nritems + push_items);
 
@@ -2632,8 +2652,9 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
        for (i = 0; i < right_nritems; i++) {
                item = btrfs_item_nr(right, i);
 
-               push_space = push_space - btrfs_item_size(right, item);
-               btrfs_set_item_offset(right, item, push_space);
+               push_space = push_space - btrfs_token_item_size(right,
+                                                               item, &token);
+               btrfs_set_token_item_offset(right, item, push_space, &token);
        }
 
        btrfs_mark_buffer_dirty(left);
@@ -2754,6 +2775,9 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
        int ret = 0;
        int wret;
        struct btrfs_disk_key disk_key;
+       struct btrfs_map_token token;
+
+       btrfs_init_map_token(&token);
 
        nritems = nritems - mid;
        btrfs_set_header_nritems(right, nritems);
@@ -2775,8 +2799,9 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
                struct btrfs_item *item = btrfs_item_nr(right, i);
                u32 ioff;
 
-               ioff = btrfs_item_offset(right, item);
-               btrfs_set_item_offset(right, item, ioff + rt_data_off);
+               ioff = btrfs_token_item_offset(right, item, &token);
+               btrfs_set_token_item_offset(right, item,
+                                           ioff + rt_data_off, &token);
        }
 
        btrfs_set_header_nritems(l, mid);
@@ -3271,6 +3296,9 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans,
        unsigned int old_size;
        unsigned int size_diff;
        int i;
+       struct btrfs_map_token token;
+
+       btrfs_init_map_token(&token);
 
        leaf = path->nodes[0];
        slot = path->slots[0];
@@ -3297,8 +3325,9 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans,
                u32 ioff;
                item = btrfs_item_nr(leaf, i);
 
-               ioff = btrfs_item_offset(leaf, item);
-               btrfs_set_item_offset(leaf, item, ioff + size_diff);
+               ioff = btrfs_token_item_offset(leaf, item, &token);
+               btrfs_set_token_item_offset(leaf, item,
+                                           ioff + size_diff, &token);
        }
 
        /* shift the data */
@@ -3368,6 +3397,9 @@ int btrfs_extend_item(struct btrfs_trans_handle *trans,
        unsigned int old_data;
        unsigned int old_size;
        int i;
+       struct btrfs_map_token token;
+
+       btrfs_init_map_token(&token);
 
        leaf = path->nodes[0];
 
@@ -3397,8 +3429,9 @@ int btrfs_extend_item(struct btrfs_trans_handle *trans,
                u32 ioff;
                item = btrfs_item_nr(leaf, i);
 
-               ioff = btrfs_item_offset(leaf, item);
-               btrfs_set_item_offset(leaf, item, ioff - data_size);
+               ioff = btrfs_token_item_offset(leaf, item, &token);
+               btrfs_set_token_item_offset(leaf, item,
+                                           ioff - data_size, &token);
        }
 
        /* shift the data */
@@ -3441,6 +3474,9 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
        unsigned int data_end;
        struct btrfs_disk_key disk_key;
        struct btrfs_key found_key;
+       struct btrfs_map_token token;
+
+       btrfs_init_map_token(&token);
 
        for (i = 0; i < nr; i++) {
                if (total_size + data_size[i] + sizeof(struct btrfs_item) >
@@ -3506,8 +3542,9 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
                        u32 ioff;
 
                        item = btrfs_item_nr(leaf, i);
-                       ioff = btrfs_item_offset(leaf, item);
-                       btrfs_set_item_offset(leaf, item, ioff - total_data);
+                       ioff = btrfs_token_item_offset(leaf, item, &token);
+                       btrfs_set_token_item_offset(leaf, item,
+                                                   ioff - total_data, &token);
                }
                /* shift the items */
                memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
@@ -3534,9 +3571,10 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
                btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
                btrfs_set_item_key(leaf, &disk_key, slot + i);
                item = btrfs_item_nr(leaf, slot + i);
-               btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
+               btrfs_set_token_item_offset(leaf, item,
+                                           data_end - data_size[i], &token);
                data_end -= data_size[i];
-               btrfs_set_item_size(leaf, item, data_size[i]);
+               btrfs_set_token_item_size(leaf, item, data_size[i], &token);
        }
        btrfs_set_header_nritems(leaf, nritems + nr);
        btrfs_mark_buffer_dirty(leaf);
@@ -3575,6 +3613,9 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
        int ret;
        struct extent_buffer *leaf;
        int slot;
+       struct btrfs_map_token token;
+
+       btrfs_init_map_token(&token);
 
        leaf = path->nodes[0];
        slot = path->slots[0];
@@ -3606,8 +3647,9 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
                        u32 ioff;
 
                        item = btrfs_item_nr(leaf, i);
-                       ioff = btrfs_item_offset(leaf, item);
-                       btrfs_set_item_offset(leaf, item, ioff - total_data);
+                       ioff = btrfs_token_item_offset(leaf, item, &token);
+                       btrfs_set_token_item_offset(leaf, item,
+                                                   ioff - total_data, &token);
                }
                /* shift the items */
                memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
@@ -3626,9 +3668,10 @@ int setup_items_for_insert(struct btrfs_trans_handle *trans,
                btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
                btrfs_set_item_key(leaf, &disk_key, slot + i);
                item = btrfs_item_nr(leaf, slot + i);
-               btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
+               btrfs_set_token_item_offset(leaf, item,
+                                           data_end - data_size[i], &token);
                data_end -= data_size[i];
-               btrfs_set_item_size(leaf, item, data_size[i]);
+               btrfs_set_token_item_size(leaf, item, data_size[i], &token);
        }
 
        btrfs_set_header_nritems(leaf, nritems + nr);
@@ -3781,7 +3824,9 @@ static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
 
        root_sub_used(root, leaf->len);
 
+       extent_buffer_get(leaf);
        btrfs_free_tree_block(trans, root, leaf, 0, 1, 0);
+       free_extent_buffer_stale(leaf);
        return 0;
 }
 /*
@@ -3799,6 +3844,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
        int wret;
        int i;
        u32 nritems;
+       struct btrfs_map_token token;
+
+       btrfs_init_map_token(&token);
 
        leaf = path->nodes[0];
        last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
@@ -3820,8 +3868,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                        u32 ioff;
 
                        item = btrfs_item_nr(leaf, i);
-                       ioff = btrfs_item_offset(leaf, item);
-                       btrfs_set_item_offset(leaf, item, ioff + dsize);
+                       ioff = btrfs_token_item_offset(leaf, item, &token);
+                       btrfs_set_token_item_offset(leaf, item,
+                                                   ioff + dsize, &token);
                }
 
                memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),