From patchwork Tue Jan 29 10:14:48 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miao Xie X-Patchwork-Id: 2060831 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 144DB3FDD1 for ; Tue, 29 Jan 2013 10:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753141Ab3A2KON (ORCPT ); Tue, 29 Jan 2013 05:14:13 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:9716 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751365Ab3A2KOL (ORCPT ); Tue, 29 Jan 2013 05:14:11 -0500 X-IronPort-AV: E=Sophos;i="4.84,559,1355068800"; d="scan'208";a="6660447" Received: from unknown (HELO tang.cn.fujitsu.com) ([10.167.250.3]) by song.cn.fujitsu.com with ESMTP; 29 Jan 2013 18:11:59 +0800 Received: from fnstmail02.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id r0TAE9sE020969 for ; Tue, 29 Jan 2013 18:14:09 +0800 Received: from [10.167.225.199] ([10.167.225.199]) by fnstmail02.fnst.cn.fujitsu.com (Lotus Domino Release 8.5.3) with ESMTP id 2013012918130363-137699 ; Tue, 29 Jan 2013 18:13:03 +0800 Message-ID: <5107A118.9040105@cn.fujitsu.com> Date: Tue, 29 Jan 2013 18:14:48 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Linux Btrfs Subject: [PATCH V2 10/10] Btrfs: use bit operation for ->fs_state References: <51079D72.7000301@cn.fujitsu.com> In-Reply-To: <51079D72.7000301@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/01/29 18:13:04, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/01/29 18:13:04, Serialize complete at 2013/01/29 18:13:04 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org There is no lock to protect fs_info->fs_state, it will introduce some problems, such as the value may be covered by the other task when several tasks modify it. For example: Task0 - CPU0 Task1 - CPU1 mov %fs_state rax or $0x1 rax mov %fs_state rax or $0x2 rax mov rax %fs_state mov rax %fs_state The expected value is 3, but in fact, it is 2. Though this problem doesn't happen now (because there is only one flag currently), the code is error prone, if we add other flags, the above problem will happen to a certainty. Now we use bit operation for it to fix the above problem. In this way, we can make the code more robust and be easy to add new flags. Signed-off-by: Miao Xie --- Changelog v1 -> v2: - modify the changelog and make it more clear and stringency. --- fs/btrfs/ctree.h | 4 +++- fs/btrfs/disk-io.c | 5 +++-- fs/btrfs/file.c | 2 +- fs/btrfs/scrub.c | 2 +- fs/btrfs/super.c | 4 ++-- fs/btrfs/transaction.c | 9 ++++----- 6 files changed, 14 insertions(+), 12 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index c95b539..c34e36e 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -338,7 +338,9 @@ static inline unsigned long btrfs_chunk_item_size(int num_stripes) /* * File system states */ +#define BTRFS_FS_STATE_ERROR 0 +/* Super block flags */ /* Errors detected */ #define BTRFS_SUPER_FLAG_ERROR (1ULL << 2) @@ -1540,7 +1542,7 @@ struct btrfs_fs_info { u64 qgroup_seq; /* filesystem state */ - u64 fs_state; + unsigned long fs_state; struct btrfs_delayed_root *delayed_root; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index a7797ed..caf329c 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2196,7 +2196,8 @@ int open_ctree(struct super_block *sb, goto fail_alloc; /* check FS state, whether FS is broken. */ - fs_info->fs_state |= btrfs_super_flags(disk_super); + if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_ERROR) + set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state); ret = btrfs_check_super_valid(fs_info, sb->s_flags & MS_RDONLY); if (ret) { @@ -3354,7 +3355,7 @@ int close_ctree(struct btrfs_root *root) printk(KERN_ERR "btrfs: commit super ret %d\n", ret); } - if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) + if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) btrfs_error_commit_super(root); btrfs_put_block_group_cache(fs_info); diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 910ea99..796fd79 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1531,7 +1531,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, * although we have opened a file as writable, we have * to stop this write operation to ensure FS consistency. */ - if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) { mutex_unlock(&inode->i_mutex); err = -EROFS; goto out; diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index af0b566..2e91b56 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -2700,7 +2700,7 @@ static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx, int ret; struct btrfs_root *root = sctx->dev_root; - if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) + if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) return -EIO; gen = atomic64_read(&root->fs_info->last_trans_committed); diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index c96f132..6528482 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -98,7 +98,7 @@ static void __save_error_info(struct btrfs_fs_info *fs_info) * today we only save the error info into ram. Long term we'll * also send it down to the disk */ - fs_info->fs_state = BTRFS_SUPER_FLAG_ERROR; + set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state); } static void save_error_info(struct btrfs_fs_info *fs_info) @@ -114,7 +114,7 @@ static void btrfs_handle_error(struct btrfs_fs_info *fs_info) if (sb->s_flags & MS_RDONLY) return; - if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) { sb->s_flags |= MS_RDONLY; printk(KERN_INFO "btrfs is forced readonly\n"); /* diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 29fdf1c..50437b4 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -62,7 +62,7 @@ static noinline int join_transaction(struct btrfs_root *root, int type) spin_lock(&fs_info->trans_lock); loop: /* The file system has been taken offline. No new transactions. */ - if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) { spin_unlock(&fs_info->trans_lock); return -EROFS; } @@ -114,7 +114,7 @@ loop: kmem_cache_free(btrfs_transaction_cachep, cur_trans); cur_trans = fs_info->running_transaction; goto loop; - } else if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) { spin_unlock(&fs_info->trans_lock); kmem_cache_free(btrfs_transaction_cachep, cur_trans); return -EROFS; @@ -302,7 +302,7 @@ start_transaction(struct btrfs_root *root, u64 num_items, int type, int ret; u64 qgroup_reserved = 0; - if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) + if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) return ERR_PTR(-EROFS); if (current->journal_info) { @@ -635,9 +635,8 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, btrfs_run_delayed_iputs(root); if (trans->aborted || - root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) { + test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) err = -EIO; - } assert_qgroups_uptodate(trans); memset(trans, 0, sizeof(*trans));