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The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array
member[1][2], introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by this
change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero." [1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
143 lines
4.2 KiB
C
143 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2011 Fujitsu. All rights reserved.
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* Written by Miao Xie <miaox@cn.fujitsu.com>
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*/
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#ifndef BTRFS_DELAYED_INODE_H
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#define BTRFS_DELAYED_INODE_H
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#include <linux/rbtree.h>
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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#include <linux/list.h>
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#include <linux/wait.h>
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#include <linux/atomic.h>
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#include <linux/refcount.h>
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#include "ctree.h"
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/* types of the delayed item */
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#define BTRFS_DELAYED_INSERTION_ITEM 1
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#define BTRFS_DELAYED_DELETION_ITEM 2
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struct btrfs_delayed_root {
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spinlock_t lock;
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struct list_head node_list;
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/*
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* Used for delayed nodes which is waiting to be dealt with by the
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* worker. If the delayed node is inserted into the work queue, we
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* drop it from this list.
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*/
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struct list_head prepare_list;
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atomic_t items; /* for delayed items */
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atomic_t items_seq; /* for delayed items */
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int nodes; /* for delayed nodes */
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wait_queue_head_t wait;
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};
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#define BTRFS_DELAYED_NODE_IN_LIST 0
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#define BTRFS_DELAYED_NODE_INODE_DIRTY 1
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#define BTRFS_DELAYED_NODE_DEL_IREF 2
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struct btrfs_delayed_node {
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u64 inode_id;
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u64 bytes_reserved;
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struct btrfs_root *root;
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/* Used to add the node into the delayed root's node list. */
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struct list_head n_list;
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/*
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* Used to add the node into the prepare list, the nodes in this list
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* is waiting to be dealt with by the async worker.
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*/
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struct list_head p_list;
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struct rb_root_cached ins_root;
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struct rb_root_cached del_root;
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struct mutex mutex;
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struct btrfs_inode_item inode_item;
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refcount_t refs;
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u64 index_cnt;
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unsigned long flags;
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int count;
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};
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struct btrfs_delayed_item {
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struct rb_node rb_node;
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struct btrfs_key key;
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struct list_head tree_list; /* used for batch insert/delete items */
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struct list_head readdir_list; /* used for readdir items */
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u64 bytes_reserved;
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struct btrfs_delayed_node *delayed_node;
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refcount_t refs;
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int ins_or_del;
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u32 data_len;
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char data[];
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};
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static inline void btrfs_init_delayed_root(
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struct btrfs_delayed_root *delayed_root)
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{
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atomic_set(&delayed_root->items, 0);
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atomic_set(&delayed_root->items_seq, 0);
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delayed_root->nodes = 0;
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spin_lock_init(&delayed_root->lock);
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init_waitqueue_head(&delayed_root->wait);
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INIT_LIST_HEAD(&delayed_root->node_list);
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INIT_LIST_HEAD(&delayed_root->prepare_list);
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}
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int btrfs_insert_delayed_dir_index(struct btrfs_trans_handle *trans,
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const char *name, int name_len,
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struct btrfs_inode *dir,
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struct btrfs_disk_key *disk_key, u8 type,
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u64 index);
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int btrfs_delete_delayed_dir_index(struct btrfs_trans_handle *trans,
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struct btrfs_inode *dir, u64 index);
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int btrfs_inode_delayed_dir_index_count(struct btrfs_inode *inode);
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int btrfs_run_delayed_items(struct btrfs_trans_handle *trans);
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int btrfs_run_delayed_items_nr(struct btrfs_trans_handle *trans, int nr);
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void btrfs_balance_delayed_items(struct btrfs_fs_info *fs_info);
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int btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,
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struct btrfs_inode *inode);
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/* Used for evicting the inode. */
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void btrfs_remove_delayed_node(struct btrfs_inode *inode);
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void btrfs_kill_delayed_inode_items(struct btrfs_inode *inode);
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int btrfs_commit_inode_delayed_inode(struct btrfs_inode *inode);
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int btrfs_delayed_update_inode(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, struct inode *inode);
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int btrfs_fill_inode(struct inode *inode, u32 *rdev);
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int btrfs_delayed_delete_inode_ref(struct btrfs_inode *inode);
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/* Used for drop dead root */
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void btrfs_kill_all_delayed_nodes(struct btrfs_root *root);
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/* Used for clean the transaction */
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void btrfs_destroy_delayed_inodes(struct btrfs_fs_info *fs_info);
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/* Used for readdir() */
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bool btrfs_readdir_get_delayed_items(struct inode *inode,
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struct list_head *ins_list,
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struct list_head *del_list);
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void btrfs_readdir_put_delayed_items(struct inode *inode,
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struct list_head *ins_list,
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struct list_head *del_list);
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int btrfs_should_delete_dir_index(struct list_head *del_list,
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u64 index);
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int btrfs_readdir_delayed_dir_index(struct dir_context *ctx,
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struct list_head *ins_list);
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/* for init */
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int __init btrfs_delayed_inode_init(void);
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void __cold btrfs_delayed_inode_exit(void);
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/* for debugging */
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void btrfs_assert_delayed_root_empty(struct btrfs_fs_info *fs_info);
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#endif
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