f2fs: compress: relocate some judgments in f2fs_reserve_compress_blocks

The following f2fs_io test will get a "0" result instead of -EINVAL,
unisoc # ./f2fs_io compress file
unisoc # ./f2fs_io reserve_cblocks file
 0
it's not reasonable, so the judgement of
atomic_read(&F2FS_I(inode)->i_compr_blocks) should be placed after
the judgement of is_inode_flag_set(inode, FI_COMPRESS_RELEASED).

Fixes: c75488fb ("f2fs: introduce F2FS_IOC_RESERVE_COMPRESS_BLOCKS")
Signed-off-by: Xiuhong Wang <xiuhong.wang@unisoc.com>
Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -3720,9 +3720,6 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
 	if (ret)
 		return ret;
 
-	if (atomic_read(&F2FS_I(inode)->i_compr_blocks))
-		goto out;
-
 	f2fs_balance_fs(sbi, true);
 
 	inode_lock(inode);
@@ -3732,6 +3729,9 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
 		goto unlock_inode;
 	}
 
+	if (atomic_read(&F2FS_I(inode)->i_compr_blocks))
+		goto unlock_inode;
+
 	f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
 	filemap_invalidate_lock(inode->i_mapping);
 
@@ -3778,7 +3778,6 @@ static int f2fs_reserve_compress_blocks(struct file *filp, unsigned long arg)
 	}
 unlock_inode:
 	inode_unlock(inode);
-out:
 	mnt_drop_write_file(filp);
 
 	if (ret >= 0) {