4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chao Yu yuchao0@huawei.com
commit 30a61ddf8117c26ac5b295e1233eaa9629a94ca3 upstream.
In below concurrent case, allocated nid can be loaded into free nid cache and be allocated again.
Thread A Thread B - f2fs_create - f2fs_new_inode - alloc_nid - __insert_nid_to_list(ALLOC_NID_LIST) - f2fs_balance_fs_bg - build_free_nids - __build_free_nids - scan_nat_page - add_free_nid - __lookup_nat_cache - f2fs_add_link - init_inode_metadata - new_inode_page - new_node_page - set_node_addr - alloc_nid_done - __remove_nid_from_list(ALLOC_NID_LIST) - __insert_nid_to_list(FREE_NID_LIST)
This patch makes nat cache lookup and free nid list operation being atomical to avoid this race condition.
Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Chao Yu yuchao0@huawei.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org [bwh: Backported to 4.4: - add_free_nid() returns 0 in case of any error (except low memory) - Tree/list addition has not been moved into __insert_nid_to_list()] Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/f2fs/node.c | 62 +++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 43 insertions(+), 19 deletions(-)
--- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -1428,8 +1428,9 @@ static void __del_from_free_nid_list(str static int add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build) { struct f2fs_nm_info *nm_i = NM_I(sbi); - struct free_nid *i; + struct free_nid *i, *e; struct nat_entry *ne; + int err = -EINVAL;
if (!available_free_memory(sbi, FREE_NIDS)) return -1; @@ -1438,35 +1439,58 @@ static int add_free_nid(struct f2fs_sb_i if (unlikely(nid == 0)) return 0;
- if (build) { - /* do not add allocated nids */ - ne = __lookup_nat_cache(nm_i, nid); - if (ne && (!get_nat_flag(ne, IS_CHECKPOINTED) || - nat_get_blkaddr(ne) != NULL_ADDR)) - return 0; - } - i = f2fs_kmem_cache_alloc(free_nid_slab, GFP_NOFS); i->nid = nid; i->state = NID_NEW;
- if (radix_tree_preload(GFP_NOFS)) { - kmem_cache_free(free_nid_slab, i); - return 0; - } + if (radix_tree_preload(GFP_NOFS)) + goto err;
spin_lock(&nm_i->free_nid_list_lock); - if (radix_tree_insert(&nm_i->free_nid_root, i->nid, i)) { - spin_unlock(&nm_i->free_nid_list_lock); - radix_tree_preload_end(); - kmem_cache_free(free_nid_slab, i); - return 0; + + if (build) { + /* + * Thread A Thread B + * - f2fs_create + * - f2fs_new_inode + * - alloc_nid + * - __insert_nid_to_list(ALLOC_NID_LIST) + * - f2fs_balance_fs_bg + * - build_free_nids + * - __build_free_nids + * - scan_nat_page + * - add_free_nid + * - __lookup_nat_cache + * - f2fs_add_link + * - init_inode_metadata + * - new_inode_page + * - new_node_page + * - set_node_addr + * - alloc_nid_done + * - __remove_nid_from_list(ALLOC_NID_LIST) + * - __insert_nid_to_list(FREE_NID_LIST) + */ + ne = __lookup_nat_cache(nm_i, nid); + if (ne && (!get_nat_flag(ne, IS_CHECKPOINTED) || + nat_get_blkaddr(ne) != NULL_ADDR)) + goto err_out; + + e = __lookup_free_nid_list(nm_i, nid); + if (e) + goto err_out; } + if (radix_tree_insert(&nm_i->free_nid_root, i->nid, i)) + goto err_out; + err = 0; list_add_tail(&i->list, &nm_i->free_nid_list); nm_i->fcnt++; +err_out: spin_unlock(&nm_i->free_nid_list_lock); radix_tree_preload_end(); - return 1; +err: + if (err) + kmem_cache_free(free_nid_slab, i); + return !err; }
static void remove_free_nid(struct f2fs_nm_info *nm_i, nid_t nid)