btrfs: Call btrfs_pin_reserved_extent only during active transaction

Calling btrfs_pin_reserved_extent makes sense only with a valid
transaction since pinned extents are processed from transaction commit
in btrfs_finish_extent_commit. In case of error it's sufficient to
adjust the reserved counter to account for log tree extents allocated in
the last transaction.

This commit moves btrfs_pin_reserved_extent to be called only with valid
transaction handle and otherwise uses the newly introduced
unaccount_log_buffer to adjust "reserved". If this is not done if a
failure occurs before transaction is committed WARN_ON are going to be
triggered on unmount. This was especially pronounced with generic/475
test.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 32b087f543f223721a7a481518878d7d3fada020..c27e121603ac6cf62372130be504e554bdbbe6df 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2695,12 +2695,10 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
                                   struct walk_control *wc)
 {
        struct btrfs_fs_info *fs_info = root->fs_info;
-       u64 root_owner;
        u64 bytenr;
        u64 ptr_gen;
        struct extent_buffer *next;
        struct extent_buffer *cur;
-       struct extent_buffer *parent;
        u32 blocksize;
        int ret = 0;
 
@@ -2720,9 +2718,6 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
                btrfs_node_key_to_cpu(cur, &first_key, path->slots[*level]);
                blocksize = fs_info->nodesize;
 
-               parent = path->nodes[*level];
-               root_owner = btrfs_header_owner(parent);
-
                next = btrfs_find_create_tree_block(fs_info, bytenr);
                if (IS_ERR(next))
                        return PTR_ERR(next);
@@ -2750,18 +2745,16 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
                                        btrfs_clean_tree_block(next);
                                        btrfs_wait_tree_block_writeback(next);
                                        btrfs_tree_unlock(next);
+                                       ret = btrfs_pin_reserved_extent(fs_info,
+                                                       bytenr, blocksize);
+                                       if (ret) {
+                                               free_extent_buffer(next);
+                                               return ret;
+                                       }
                                } else {
                                        if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
                                                clear_extent_buffer_dirty(next);
-                               }
-
-                               WARN_ON(root_owner !=
-                                       BTRFS_TREE_LOG_OBJECTID);
-                               ret = btrfs_pin_reserved_extent(fs_info,
-                                                       bytenr, blocksize);
-                               if (ret) {
-                                       free_extent_buffer(next);
-                                       return ret;
+                                       unaccount_log_buffer(fs_info, bytenr);
                                }
                        }
                        free_extent_buffer(next);
@@ -2792,7 +2785,6 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
                                 struct walk_control *wc)
 {
        struct btrfs_fs_info *fs_info = root->fs_info;
-       u64 root_owner;
        int i;
        int slot;
        int ret;
@@ -2805,13 +2797,6 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
                        WARN_ON(*level == 0);
                        return 0;
                } else {
-                       struct extent_buffer *parent;
-                       if (path->nodes[*level] == root->node)
-                               parent = path->nodes[*level];
-                       else
-                               parent = path->nodes[*level + 1];
-
-                       root_owner = btrfs_header_owner(parent);
                        ret = wc->process_func(root, path->nodes[*level], wc,
                                 btrfs_header_generation(path->nodes[*level]),
                                 *level);
@@ -2829,17 +2814,18 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
                                        btrfs_clean_tree_block(next);
                                        btrfs_wait_tree_block_writeback(next);
                                        btrfs_tree_unlock(next);
+                                       ret = btrfs_pin_reserved_extent(fs_info,
+                                                    path->nodes[*level]->start,
+                                                    path->nodes[*level]->len);
+                                       if (ret)
+                                               return ret;
                                } else {
                                        if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
                                                clear_extent_buffer_dirty(next);
-                               }
 
-                               WARN_ON(root_owner != BTRFS_TREE_LOG_OBJECTID);
-                               ret = btrfs_pin_reserved_extent(fs_info,
-                                               path->nodes[*level]->start,
-                                               path->nodes[*level]->len);
-                               if (ret)
-                                       return ret;
+                                       unaccount_log_buffer(fs_info,
+                                               path->nodes[*level]->start);
+                               }
                        }
                        free_extent_buffer(path->nodes[*level]);
                        path->nodes[*level] = NULL;
@@ -2910,15 +2896,15 @@ static int walk_log_tree(struct btrfs_trans_handle *trans,
                                btrfs_clean_tree_block(next);
                                btrfs_wait_tree_block_writeback(next);
                                btrfs_tree_unlock(next);
+                               ret = btrfs_pin_reserved_extent(fs_info,
+                                               next->start, next->len);
+                               if (ret)
+                                       goto out;
                        } else {
                                if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
                                        clear_extent_buffer_dirty(next);
+                               unaccount_log_buffer(fs_info, next->start);
                        }
-
-                       ret = btrfs_pin_reserved_extent(fs_info, next->start,
-                                                       next->len);
-                       if (ret)
-                               goto out;
                }
        }