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Groups > linux.kernel > #1485845

[PATCH 3/6] f2fs: fix to avoid race condition when updating sbi flag

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From: Chao Yu <yuchao0@huawei.com>

Making updating of sbi flag atomic by using {test,set,clear}_bit,
otherwise in concurrency scenario, the flag could be updated incorrectly.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 fs/f2fs/f2fs.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9b4bbf2..c30f744b 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -794,7 +794,7 @@ struct f2fs_sb_info {
 	struct proc_dir_entry *s_proc;		/* proc entry */
 	struct f2fs_super_block *raw_super;	/* raw super block pointer */
 	int valid_super_block;			/* valid super block no */
-	int s_flag;				/* flags for sbi */
+	unsigned long s_flag;				/* flags for sbi */
 
 #ifdef CONFIG_F2FS_FS_ENCRYPTION
 	u8 key_prefix[F2FS_KEY_DESC_PREFIX_SIZE];
@@ -1063,17 +1063,19 @@ static inline struct address_space *NODE_MAPPING(struct f2fs_sb_info *sbi)
 
 static inline bool is_sbi_flag_set(struct f2fs_sb_info *sbi, unsigned int type)
 {
-	return sbi->s_flag & (0x01 << type);
+	return test_bit(type, &sbi->s_flag);
 }
 
 static inline void set_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
 {
-	sbi->s_flag |= (0x01 << type);
+	if (!test_bit(type, &sbi->s_flag))
+		set_bit(type, &sbi->s_flag);
 }
 
 static inline void clear_sbi_flag(struct f2fs_sb_info *sbi, unsigned int type)
 {
-	sbi->s_flag &= ~(0x01 << type);
+	if (test_bit(type, &sbi->s_flag))
+		clear_bit(type, &sbi->s_flag);
 }
 
 static inline unsigned long long cur_cp_version(struct f2fs_checkpoint *cp)
-- 
2.7.2

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[PATCH 1/6] f2fs: make f2fs_filetype_table static Chao Yu <chao@kernel.org> - 2016-09-18 17:40 +0200
  [PATCH 3/6] f2fs: fix to avoid race condition when updating sbi flag Chao Yu <chao@kernel.org> - 2016-09-18 17:40 +0200
    Re: [PATCH 3/6] f2fs: fix to avoid race condition when updating sbi  flag Jaegeuk Kim <jaegeuk@kernel.org> - 2016-09-19 23:50 +0200
      Re: [PATCH 3/6] f2fs: fix to avoid race condition when updating sbi  flag Chao Yu <yuchao0@huawei.com> - 2016-09-20 03:50 +0200
  [PATCH 2/6] f2fs: fix to return error number of read_all_xattrs correctly Chao Yu <chao@kernel.org> - 2016-09-18 17:40 +0200

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