When running functions that can make changes to the internal trees
(e.g. btrfs_search_slot), we check if somebody may be interested in the
block we're currently modifying. If so, we record our modification to be
able to rewind it later on.

Signed-off-by: Jan Schmidt <list.bt...@jan-o-sch.net>
---
 fs/btrfs/ctree.c |  126 ++++++++++++++++++++++++++++++++++--------------------
 1 files changed, 79 insertions(+), 47 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 6420638..724eade 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -38,7 +38,18 @@ static int balance_node_right(struct btrfs_trans_handle 
*trans,
                              struct extent_buffer *dst_buf,
                              struct extent_buffer *src_buf);
 static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                  struct btrfs_path *path, int level, int slot);
+                   struct btrfs_path *path, int level, int slot,
+                   int tree_mod_log);
+static inline void set_root_pointer(struct btrfs_root *root,
+                                   struct extent_buffer *new_root_node);
+static void __log_cleaning(struct btrfs_fs_info *fs_info,
+                          struct extent_buffer *eb);
+struct extent_buffer *read_old_tree_block(struct btrfs_root *root, u64 bytenr,
+                                         u32 blocksize, u64 parent_transid,
+                                         u64 time_seq);
+struct extent_buffer *btrfs_find_old_tree_block(struct btrfs_root *root,
+                                               u64 bytenr, u32 blocksize,
+                                               u64 time_seq);
 
 struct btrfs_path *btrfs_alloc_path(void)
 {
@@ -678,6 +689,9 @@ static void __log_cleaning(struct btrfs_fs_info *fs_info,
        int ret;
        u32 nritems;
 
+       if (btrfs_header_level(eb) == 0)
+               return;
+
        nritems = btrfs_header_nritems(eb);
        for (i = nritems - 1; i >= 0; i--) {
                ret = tree_mod_log_insert_key(fs_info, eb, i,
@@ -818,6 +832,9 @@ static noinline int update_ref_for_cow(struct 
btrfs_trans_handle *trans,
                        ret = btrfs_dec_ref(trans, root, buf, 1, 1);
                        BUG_ON(ret); /* -ENOMEM */
                }
+               /* the root node will be logged in set_root_pointer later */
+               if (buf != root->node && btrfs_header_level(buf) != 0)
+                       __log_cleaning(root->fs_info, buf);
                clean_tree_block(trans, root, buf);
                *last_ref = 1;
        }
@@ -915,7 +932,7 @@ static noinline int __btrfs_cow_block(struct 
btrfs_trans_handle *trans,
                        parent_start = 0;
 
                extent_buffer_get(cow);
-               rcu_assign_pointer(root->node, cow);
+               set_root_pointer(root, cow);
 
                btrfs_free_tree_block(trans, root, buf, parent_start,
                                      last_ref);
@@ -928,6 +945,8 @@ static noinline int __btrfs_cow_block(struct 
btrfs_trans_handle *trans,
                        parent_start = 0;
 
                WARN_ON(trans->transid != btrfs_header_generation(parent));
+               tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
+                                       MOD_LOG_KEY_REPLACE);
                btrfs_set_node_blockptr(parent, parent_slot,
                                        cow->start);
                btrfs_set_node_ptr_generation(parent, parent_slot,
@@ -1383,7 +1402,9 @@ static noinline int balance_level(struct 
btrfs_trans_handle *trans,
                        goto enospc;
                }
 
-               rcu_assign_pointer(root->node, child);
+               ret = tree_mod_log_insert_key(root->fs_info, mid, 0,
+                                             MOD_LOG_KEY_REMOVE);
+               set_root_pointer(root, child);
 
                add_root_to_dirty_list(root);
                btrfs_tree_unlock(child);
@@ -1449,7 +1470,7 @@ static noinline int balance_level(struct 
btrfs_trans_handle *trans,
                if (btrfs_header_nritems(right) == 0) {
                        clean_tree_block(trans, root, right);
                        btrfs_tree_unlock(right);
-                       del_ptr(trans, root, path, level + 1, pslot + 1);
+                       del_ptr(trans, root, path, level + 1, pslot + 1, 1);
                        root_sub_used(root, right->len);
                        btrfs_free_tree_block(trans, root, right, 0, 1);
                        free_extent_buffer_stale(right);
@@ -1457,7 +1478,8 @@ static noinline int balance_level(struct 
btrfs_trans_handle *trans,
                } else {
                        struct btrfs_disk_key right_key;
                        btrfs_node_key(right, &right_key, 0);
-                       btrfs_set_node_key(parent, &right_key, pslot + 1);
+                       __set_node_key_log(root->fs_info, parent,
+                                          &right_key, pslot + 1, 0);
                        btrfs_mark_buffer_dirty(parent);
                }
        }
@@ -1491,7 +1513,7 @@ static noinline int balance_level(struct 
btrfs_trans_handle *trans,
        if (btrfs_header_nritems(mid) == 0) {
                clean_tree_block(trans, root, mid);
                btrfs_tree_unlock(mid);
-               del_ptr(trans, root, path, level + 1, pslot);
+               del_ptr(trans, root, path, level + 1, pslot, 1);
                root_sub_used(root, mid->len);
                btrfs_free_tree_block(trans, root, mid, 0, 1);
                free_extent_buffer_stale(mid);
@@ -1500,7 +1522,7 @@ static noinline int balance_level(struct 
btrfs_trans_handle *trans,
                /* update the parent key to reflect our changes */
                struct btrfs_disk_key mid_key;
                btrfs_node_key(mid, &mid_key, 0);
-               btrfs_set_node_key(parent, &mid_key, pslot);
+               __set_node_key_log(root->fs_info, parent, &mid_key, pslot, 0);
                btrfs_mark_buffer_dirty(parent);
        }
 
@@ -1597,7 +1619,8 @@ static noinline int push_nodes_for_insert(struct 
btrfs_trans_handle *trans,
                        struct btrfs_disk_key disk_key;
                        orig_slot += left_nr;
                        btrfs_node_key(mid, &disk_key, 0);
-                       btrfs_set_node_key(parent, &disk_key, pslot);
+                       __set_node_key_log(root->fs_info, parent, &disk_key,
+                                          pslot, 0);
                        btrfs_mark_buffer_dirty(parent);
                        if (btrfs_header_nritems(left) > orig_slot) {
                                path->nodes[level] = left;
@@ -1648,7 +1671,8 @@ static noinline int push_nodes_for_insert(struct 
btrfs_trans_handle *trans,
                        struct btrfs_disk_key disk_key;
 
                        btrfs_node_key(right, &disk_key, 0);
-                       btrfs_set_node_key(parent, &disk_key, pslot + 1);
+                       __set_node_key_log(root->fs_info, parent, &disk_key,
+                                          pslot + 1, 0);
                        btrfs_mark_buffer_dirty(parent);
 
                        if (btrfs_header_nritems(mid) <= orig_slot) {
@@ -2350,7 +2374,7 @@ static void fixup_low_keys(struct btrfs_trans_handle 
*trans,
                if (!path->nodes[i])
                        break;
                t = path->nodes[i];
-               btrfs_set_node_key(t, key, tslot);
+               __set_node_key_log(root->fs_info, t, key, tslot, 1);
                btrfs_mark_buffer_dirty(path->nodes[i]);
                if (tslot != 0)
                        break;
@@ -2432,16 +2456,14 @@ static int push_node_left(struct btrfs_trans_handle 
*trans,
        } else
                push_items = min(src_nritems - 8, push_items);
 
-       copy_extent_buffer(dst, src,
-                          btrfs_node_key_ptr_offset(dst_nritems),
-                          btrfs_node_key_ptr_offset(0),
-                          push_items * sizeof(struct btrfs_key_ptr));
+
+       __copy_extent_buffer_log(root->fs_info, dst, src, dst_nritems, 0,
+                                push_items, sizeof(struct btrfs_key_ptr));
 
        if (push_items < src_nritems) {
-               memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
-                                     btrfs_node_key_ptr_offset(push_items),
-                                     (src_nritems - push_items) *
-                                     sizeof(struct btrfs_key_ptr));
+               __memmove_extent_buffer_log(root->fs_info, src, 0, push_items,
+                                       src_nritems - push_items,
+                                       sizeof(struct btrfs_key_ptr), 1);
        }
        btrfs_set_header_nritems(src, src_nritems - push_items);
        btrfs_set_header_nritems(dst, dst_nritems + push_items);
@@ -2491,15 +2513,13 @@ static int balance_node_right(struct btrfs_trans_handle 
*trans,
        if (max_push < push_items)
                push_items = max_push;
 
-       memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
-                                     btrfs_node_key_ptr_offset(0),
-                                     (dst_nritems) *
-                                     sizeof(struct btrfs_key_ptr));
+       __memmove_extent_buffer_log(root->fs_info, dst, push_items, 0,
+                                   dst_nritems,
+                                   sizeof(struct btrfs_key_ptr), 1);
 
-       copy_extent_buffer(dst, src,
-                          btrfs_node_key_ptr_offset(0),
-                          btrfs_node_key_ptr_offset(src_nritems - push_items),
-                          push_items * sizeof(struct btrfs_key_ptr));
+       __copy_extent_buffer_log(root->fs_info, dst, src, 0,
+                                src_nritems - push_items,
+                                push_items, sizeof(struct btrfs_key_ptr));
 
        btrfs_set_header_nritems(src, src_nritems - push_items);
        btrfs_set_header_nritems(dst, dst_nritems + push_items);
@@ -2570,7 +2590,7 @@ static noinline int insert_new_root(struct 
btrfs_trans_handle *trans,
        btrfs_mark_buffer_dirty(c);
 
        old = root->node;
-       rcu_assign_pointer(root->node, c);
+       set_root_pointer(root, c);
 
        /* the super has an extra ref to root->node */
        free_extent_buffer(old);
@@ -2593,10 +2613,11 @@ static noinline int insert_new_root(struct 
btrfs_trans_handle *trans,
 static void insert_ptr(struct btrfs_trans_handle *trans,
                       struct btrfs_root *root, struct btrfs_path *path,
                       struct btrfs_disk_key *key, u64 bytenr,
-                      int slot, int level)
+                      int slot, int level, int tree_mod_log)
 {
        struct extent_buffer *lower;
        int nritems;
+       int ret;
 
        BUG_ON(!path->nodes[level]);
        btrfs_assert_tree_locked(path->nodes[level]);
@@ -2605,10 +2626,15 @@ static void insert_ptr(struct btrfs_trans_handle *trans,
        BUG_ON(slot > nritems);
        BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
        if (slot != nritems) {
-               memmove_extent_buffer(lower,
-                             btrfs_node_key_ptr_offset(slot + 1),
-                             btrfs_node_key_ptr_offset(slot),
-                             (nritems - slot) * sizeof(struct btrfs_key_ptr));
+               __memmove_extent_buffer_log(root->fs_info, lower, slot + 1,
+                                           slot, nritems - slot,
+                                           sizeof(struct btrfs_key_ptr),
+                                           tree_mod_log && level);
+       }
+       if (tree_mod_log && level) {
+               ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
+                                             MOD_LOG_KEY_ADD);
+               BUG_ON(ret < 0);
        }
        btrfs_set_node_key(lower, key, slot);
        btrfs_set_node_blockptr(lower, slot, bytenr);
@@ -2681,10 +2707,8 @@ static noinline int split_node(struct btrfs_trans_handle 
*trans,
                            BTRFS_UUID_SIZE);
 
 
-       copy_extent_buffer(split, c,
-                          btrfs_node_key_ptr_offset(0),
-                          btrfs_node_key_ptr_offset(mid),
-                          (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
+       __copy_extent_buffer_log(root->fs_info, split, c, 0, mid,
+                                c_nritems - mid, sizeof(struct btrfs_key_ptr));
        btrfs_set_header_nritems(split, c_nritems - mid);
        btrfs_set_header_nritems(c, mid);
        ret = 0;
@@ -2693,7 +2717,7 @@ static noinline int split_node(struct btrfs_trans_handle 
*trans,
        btrfs_mark_buffer_dirty(split);
 
        insert_ptr(trans, root, path, &disk_key, split->start,
-                  path->slots[level + 1] + 1, level + 1);
+                  path->slots[level + 1] + 1, level + 1, 1);
 
        if (path->slots[level] >= mid) {
                path->slots[level] -= mid;
@@ -3230,7 +3254,7 @@ static noinline void copy_for_split(struct 
btrfs_trans_handle *trans,
        btrfs_set_header_nritems(l, mid);
        btrfs_item_key(right, &disk_key, 0);
        insert_ptr(trans, root, path, &disk_key, right->start,
-                  path->slots[1] + 1, 1);
+                  path->slots[1] + 1, 1, 0);
 
        btrfs_mark_buffer_dirty(right);
        btrfs_mark_buffer_dirty(l);
@@ -3437,7 +3461,7 @@ again:
                if (mid <= slot) {
                        btrfs_set_header_nritems(right, 0);
                        insert_ptr(trans, root, path, &disk_key, right->start,
-                                  path->slots[1] + 1, 1);
+                                  path->slots[1] + 1, 1, 0);
                        btrfs_tree_unlock(path->nodes[0]);
                        free_extent_buffer(path->nodes[0]);
                        path->nodes[0] = right;
@@ -3446,7 +3470,7 @@ again:
                } else {
                        btrfs_set_header_nritems(right, 0);
                        insert_ptr(trans, root, path, &disk_key, right->start,
-                                         path->slots[1], 1);
+                                         path->slots[1], 1, 0);
                        btrfs_tree_unlock(path->nodes[0]);
                        free_extent_buffer(path->nodes[0]);
                        path->nodes[0] = right;
@@ -4158,19 +4182,27 @@ int btrfs_insert_item(struct btrfs_trans_handle *trans, 
struct btrfs_root
  * empty a node.
  */
 static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                   struct btrfs_path *path, int level, int slot)
+                   struct btrfs_path *path, int level, int slot,
+                   int tree_mod_log)
 {
        struct extent_buffer *parent = path->nodes[level];
        u32 nritems;
+       int ret;
 
        nritems = btrfs_header_nritems(parent);
        if (slot != nritems - 1) {
-               memmove_extent_buffer(parent,
-                             btrfs_node_key_ptr_offset(slot),
-                             btrfs_node_key_ptr_offset(slot + 1),
-                             sizeof(struct btrfs_key_ptr) *
-                             (nritems - slot - 1));
+               __memmove_extent_buffer_log(root->fs_info, parent, slot,
+                                           slot + 1, nritems - slot - 1,
+                                           sizeof(struct btrfs_key_ptr),
+                                           tree_mod_log && level);
        }
+
+       if (tree_mod_log && level) {
+               ret = tree_mod_log_insert_key(root->fs_info, parent, slot,
+                                             MOD_LOG_KEY_REMOVE);
+               BUG_ON(ret < 0);
+       }
+
        nritems--;
        btrfs_set_header_nritems(parent, nritems);
        if (nritems == 0 && parent == root->node) {
@@ -4202,7 +4234,7 @@ static noinline void btrfs_del_leaf(struct 
btrfs_trans_handle *trans,
                                    struct extent_buffer *leaf)
 {
        WARN_ON(btrfs_header_generation(leaf) != trans->transid);
-       del_ptr(trans, root, path, 1, path->slots[1]);
+       del_ptr(trans, root, path, 1, path->slots[1], 1);
 
        /*
         * btrfs_free_extent is expensive, we want to make sure we
-- 
1.7.3.4

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