f2fs: allow to clear F2FS_COMPR_FL flag

If regular inode has no compressed cluster, allow using 'chattr -c'
to remove its compress flag, recovering it to a non-compressed file.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -1817,10 +1817,10 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
 	}
 
 	if ((iflags ^ masked_flags) & F2FS_COMPR_FL) {
-		if (S_ISREG(inode->i_mode) &&
-			(masked_flags & F2FS_COMPR_FL || i_size_read(inode) ||
-						F2FS_HAS_BLOCKS(inode)))
-			return -EINVAL;
+		if (S_ISREG(inode->i_mode) && (masked_flags & F2FS_COMPR_FL)) {
+			if (f2fs_disable_compressed_file(inode))
+				return -EINVAL;
+		}
 		if (iflags & F2FS_NOCOMP_FL)
 			return -EINVAL;
 		if (iflags & F2FS_COMPR_FL) {