[PATCH] erofs: clean up z_erofs_load_full_lcluster()

[Gao Xiang]

Only four lcluster types here, remove redundant code.
No real logic changes.

Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
---
Some random cleanup out of the upcoming big lclusters..

 fs/erofs/erofs_fs.h |  5 +----
 fs/erofs/zmap.c     | 21 +++++----------------
 2 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
index 4bc11602aac8..6c0c270c42e1 100644
--- a/fs/erofs/erofs_fs.h
+++ b/fs/erofs/erofs_fs.h
@@ -406,8 +406,7 @@ enum {
        Z_EROFS_LCLUSTER_TYPE_MAX
 };
 
-#define Z_EROFS_LI_LCLUSTER_TYPE_BITS        2
-#define Z_EROFS_LI_LCLUSTER_TYPE_BIT         0
+#define Z_EROFS_LI_LCLUSTER_TYPE_MASK  (Z_EROFS_LCLUSTER_TYPE_MAX - 1)
 
 /* (noncompact only, HEAD) This pcluster refers to partial decompressed data */
 #define Z_EROFS_LI_PARTIAL_REF         (1 << 15)
@@ -461,8 +460,6 @@ static inline void 
erofs_check_ondisk_layout_definitions(void)
                     sizeof(struct z_erofs_lcluster_index));
        BUILD_BUG_ON(sizeof(struct erofs_deviceslot) != 128);
 
-       BUILD_BUG_ON(BIT(Z_EROFS_LI_LCLUSTER_TYPE_BITS) <
-                    Z_EROFS_LCLUSTER_TYPE_MAX - 1);
        /* exclude old compiler versions like gcc 7.5.0 */
        BUILD_BUG_ON(__builtin_constant_p(fmh) ?
                     fmh != cpu_to_le64(1ULL << 63) : 0);
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index e313c936351d..26637a60eba5 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -31,7 +31,7 @@ static int z_erofs_load_full_lcluster(struct 
z_erofs_maprecorder *m,
                        vi->inode_isize + vi->xattr_isize) +
                        lcn * sizeof(struct z_erofs_lcluster_index);
        struct z_erofs_lcluster_index *di;
-       unsigned int advise, type;
+       unsigned int advise;
 
        m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,
                                      erofs_blknr(inode->i_sb, pos), 
EROFS_KMAP);
@@ -43,10 +43,8 @@ static int z_erofs_load_full_lcluster(struct 
z_erofs_maprecorder *m,
        di = m->kaddr + erofs_blkoff(inode->i_sb, pos);
 
        advise = le16_to_cpu(di->di_advise);
-       type = (advise >> Z_EROFS_LI_LCLUSTER_TYPE_BIT) &
-               ((1 << Z_EROFS_LI_LCLUSTER_TYPE_BITS) - 1);
-       switch (type) {
-       case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
+       m->type = advise & Z_EROFS_LI_LCLUSTER_TYPE_MASK;
+       if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
                m->clusterofs = 1 << vi->z_logical_clusterbits;
                m->delta[0] = le16_to_cpu(di->di_u.delta[0]);
                if (m->delta[0] & Z_EROFS_LI_D0_CBLKCNT) {
@@ -60,24 +58,15 @@ static int z_erofs_load_full_lcluster(struct 
z_erofs_maprecorder *m,
                        m->delta[0] = 1;
                }
                m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
-               break;
-       case Z_EROFS_LCLUSTER_TYPE_PLAIN:
-       case Z_EROFS_LCLUSTER_TYPE_HEAD1:
-       case Z_EROFS_LCLUSTER_TYPE_HEAD2:
-               if (advise & Z_EROFS_LI_PARTIAL_REF)
-                       m->partialref = true;
+       } else {
+               m->partialref = !!(advise & Z_EROFS_LI_PARTIAL_REF);
                m->clusterofs = le16_to_cpu(di->di_clusterofs);
                if (m->clusterofs >= 1 << vi->z_logical_clusterbits) {
                        DBG_BUGON(1);
                        return -EFSCORRUPTED;
                }
                m->pblk = le32_to_cpu(di->di_u.blkaddr);
-               break;
-       default:
-               DBG_BUGON(1);
-               return -EOPNOTSUPP;
        }
-       m->type = type;
        return 0;
 }
 
-- 
2.39.3