erofs: clean up erofs_iget()

Move inode hash function into inode.c and simplify erofs_iget().

Link: https://lore.kernel.org/r/20230113065226.68801-1-hsiangkao@linux.alibaba.comReviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/inode.c

@@ -308,47 +308,49 @@ static int erofs_fill_inode(struct inode *inode)
 }
 
 /*
- * erofs nid is 64bits, but i_ino is 'unsigned long', therefore
- * we should do more for 32-bit platform to find the right inode.
+ * ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
+ * so that it will fit.
  */
-static int erofs_ilookup_test_actor(struct inode *inode, void *opaque)
+static ino_t erofs_squash_ino(erofs_nid_t nid)
 {
-	const erofs_nid_t nid = *(erofs_nid_t *)opaque;
+	ino_t ino = (ino_t)nid;
+
+	if (sizeof(ino_t) < sizeof(erofs_nid_t))
+		ino ^= nid >> (sizeof(erofs_nid_t) - sizeof(ino_t)) * 8;
+	return ino;
+}
 
-	return EROFS_I(inode)->nid == nid;
+static int erofs_iget5_eq(struct inode *inode, void *opaque)
+{
+	return EROFS_I(inode)->nid == *(erofs_nid_t *)opaque;
 }
 
-static int erofs_iget_set_actor(struct inode *inode, void *opaque)
+static int erofs_iget5_set(struct inode *inode, void *opaque)
 {
 	const erofs_nid_t nid = *(erofs_nid_t *)opaque;
 
-	inode->i_ino = erofs_inode_hash(nid);
+	inode->i_ino = erofs_squash_ino(nid);
+	EROFS_I(inode)->nid = nid;
 	return 0;
 }
 
 struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid)
 {
-	const unsigned long hashval = erofs_inode_hash(nid);
 	struct inode *inode;
 
-	inode = iget5_locked(sb, hashval, erofs_ilookup_test_actor,
-		erofs_iget_set_actor, &nid);
+	inode = iget5_locked(sb, erofs_squash_ino(nid), erofs_iget5_eq,
+			     erofs_iget5_set, &nid);
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
 	if (inode->i_state & I_NEW) {
-		int err;
-		struct erofs_inode *vi = EROFS_I(inode);
-
-		vi->nid = nid;
+		int err = erofs_fill_inode(inode);
 
-		err = erofs_fill_inode(inode);
-		if (!err) {
-			unlock_new_inode(inode);
-		} else {
+		if (err) {
 			iget_failed(inode);
-			inode = ERR_PTR(err);
+			return ERR_PTR(err);
 		}
+		unlock_new_inode(inode);
 	}
 	return inode;
 }

fs/erofs/internal.h

@@ -480,15 +480,6 @@ int erofs_map_blocks(struct inode *inode,
 		     struct erofs_map_blocks *map, int flags);
 
 /* inode.c */
-static inline unsigned long erofs_inode_hash(erofs_nid_t nid)
-{
-#if BITS_PER_LONG == 32
-	return (nid >> 32) ^ (nid & 0xffffffff);
-#else
-	return nid;
-#endif
-}
-
 extern const struct inode_operations erofs_generic_iops;
 extern const struct inode_operations erofs_symlink_iops;
 extern const struct inode_operations erofs_fast_symlink_iops;