erofs: introduce erofs_sb_has_xxx() helpers

Introduce erofs_sb_has_xxx() to make long checks short, especially
for later big pcluster & LZMA features.

Link: https://lore.kernel.org/r/20210329012308.28743-2-hsiangkao@aol.comReviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

fs/erofs/decompressor.c

@@ -124,8 +124,7 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
 	support_0padding = false;
 
 	/* decompression inplace is only safe when 0padding is enabled */
-	if (EROFS_SB(rq->sb)->feature_incompat &
-	    EROFS_FEATURE_INCOMPAT_LZ4_0PADDING) {
+	if (erofs_sb_has_lz4_0padding(EROFS_SB(rq->sb))) {
 		support_0padding = true;
 
 		while (!src[inputmargin & ~PAGE_MASK])

fs/erofs/internal.h

@@ -218,6 +218,15 @@ static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid)
 	return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);
 }
 
+#define EROFS_FEATURE_FUNCS(name, compat, feature) \
+static inline bool erofs_sb_has_##name(struct erofs_sb_info *sbi) \
+{ \
+	return sbi->feature_##compat & EROFS_FEATURE_##feature; \
+}
+
+EROFS_FEATURE_FUNCS(lz4_0padding, incompat, INCOMPAT_LZ4_0PADDING)
+EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
+
 /* atomic flag definitions */
 #define EROFS_I_EA_INITED_BIT	0
 #define EROFS_I_Z_INITED_BIT	1

fs/erofs/super.c

@@ -149,7 +149,7 @@ static int erofs_read_superblock(struct super_block *sb)
 	}
 
 	sbi->feature_compat = le32_to_cpu(dsb->feature_compat);
-	if (sbi->feature_compat & EROFS_FEATURE_COMPAT_SB_CHKSUM) {
+	if (erofs_sb_has_sb_chksum(sbi)) {
 		ret = erofs_superblock_csum_verify(sb, data);
 		if (ret)
 			goto out;