[PATCH 10/11] Btrfs: use bit operation for ->fs_state

[Miao Xie <miaox@cn.fujitsu.com>]

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. Now we use bit operation for it to fix the above problem.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
---
 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 cf03a45..d06e50c 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 3e9fa0e..ec87b69 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 6f0524d..f714379 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 7999bf8..a950d48 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));
-- 
1.7.11.7