f2fs: compress: fix to relocate check condition in f2fs_ioc_{,de}compress_file()

Compress flag should be checked after inode lock held to avoid
racing w/ f2fs_setflags_common() , fix it.

Fixes: 5fdb322 ("f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE")
Reported-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Closes: https://lore.kernel.org/linux-f2fs-devel/CAHJ8P3LdZXLc2rqeYjvymgYHr2+YLuJ0sLG9DdsJZmwO7deuhw@mail.gmail.com
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: chaseyu

fs/f2fs/file.c

@@ -4136,9 +4136,6 @@ static int f2fs_ioc_decompress_file(struct file *filp)
 	if (!(filp->f_mode & FMODE_WRITE))
 		return -EBADF;
 
-	if (!f2fs_compressed_file(inode))
-		return -EINVAL;
-
 	f2fs_balance_fs(sbi, true);
 
 	file_start_write(filp);
@@ -4149,7 +4146,8 @@ static int f2fs_ioc_decompress_file(struct file *filp)
 		goto out;
 	}
 
-	if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
+	if (!f2fs_compressed_file(inode) ||
+		is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -4214,9 +4212,6 @@ static int f2fs_ioc_compress_file(struct file *filp)
 	if (!(filp->f_mode & FMODE_WRITE))
 		return -EBADF;
 
-	if (!f2fs_compressed_file(inode))
-		return -EINVAL;
-
 	f2fs_balance_fs(sbi, true);
 
 	file_start_write(filp);
@@ -4227,7 +4222,8 @@ static int f2fs_ioc_compress_file(struct file *filp)
 		goto out;
 	}
 
-	if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
+	if (!f2fs_compressed_file(inode) ||
+		is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
 		ret = -EINVAL;
 		goto out;
 	}