f2fs: introduce sb_lock to make encrypt pwsalt update exclusive
f2fs_super_block.encrypt_pw_salt can be udpated and persisted
concurrently, result in getting different pwsalt in separated
threads, so let's introduce sb_lock to exclude concurrent
accessers.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index d61b751..24cb9ec 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1956,13 +1956,15 @@
if (!f2fs_sb_has_encrypt(inode->i_sb))
return -EOPNOTSUPP;
- if (uuid_is_nonzero(sbi->raw_super->encrypt_pw_salt))
- goto got_it;
-
err = mnt_want_write_file(filp);
if (err)
return err;
+ mutex_lock(&sbi->sb_lock);
+
+ if (uuid_is_nonzero(sbi->raw_super->encrypt_pw_salt))
+ goto got_it;
+
/* update superblock with uuid */
generate_random_uuid(sbi->raw_super->encrypt_pw_salt);
@@ -1970,15 +1972,16 @@
if (err) {
/* undo new data */
memset(sbi->raw_super->encrypt_pw_salt, 0, 16);
- mnt_drop_write_file(filp);
- return err;
+ goto out_err;
}
- mnt_drop_write_file(filp);
got_it:
if (copy_to_user((__u8 __user *)arg, sbi->raw_super->encrypt_pw_salt,
16))
- return -EFAULT;
- return 0;
+ err = -EFAULT;
+out_err:
+ mutex_unlock(&sbi->sb_lock);
+ mnt_drop_write_file(filp);
+ return err;
}
static int f2fs_ioc_gc(struct file *filp, unsigned long arg)