f2fs: do not set compression bit if kernel doesn't support

If kernel doesn't have CONFIG_F2FS_FS_COMPRESSION, a file having FS_COMPR_FL via
ioctl(FS_IOC_SETFLAGS) is unaccessible due to f2fs_is_compress_backend_ready().
Let's avoid it.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -4292,8 +4292,9 @@ static inline void f2fs_update_extent_tree_range_compressed(struct inode *inode,
 				unsigned int c_len) { }
 #endif
 
-static inline void set_compress_context(struct inode *inode)
+static inline int set_compress_context(struct inode *inode)
 {
+#ifdef CONFIG_F2FS_FS_COMPRESSION
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 
 	F2FS_I(inode)->i_compress_algorithm =
@@ -4316,6 +4317,10 @@ static inline void set_compress_context(struct inode *inode)
 	stat_inc_compr_inode(inode);
 	inc_compr_inode_stat(inode);
 	f2fs_mark_inode_dirty_sync(inode, true);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
 }
 
 static inline bool f2fs_disable_compressed_file(struct inode *inode)

fs/f2fs/file.c

@@ -1878,8 +1878,8 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
 				return -EINVAL;
 			if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
 				return -EINVAL;
-
-			set_compress_context(inode);
+			if (set_compress_context(inode))
+				return -EOPNOTSUPP;
 		}
 	}