exfat: use exfat_chain_advance helper

Replace open-coded cluster chain walking logic with exfat_chain_advance()
across exfat_readdir, exfat_find_dir_entry, exfat_count_dir_entries,
exfat_search_empty_slot and exfat_check_dir_empty.

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

Author: Chi Zhiling

fs/exfat/dir.c

@@ -93,25 +93,19 @@ static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_ent
 	clu_offset = EXFAT_DEN_TO_CLU(dentry, sbi);
 	exfat_chain_dup(&clu, &dir);
 
-	if (clu.flags == ALLOC_NO_FAT_CHAIN) {
-		clu.dir += clu_offset;
-		clu.size -= clu_offset;
-	} else {
+	if (clu.flags == ALLOC_FAT_CHAIN) {
 		/* hint_information */
 		if (clu_offset > 0 && ei->hint_bmap.off != EXFAT_EOF_CLUSTER &&
 		    ei->hint_bmap.off > 0 && clu_offset >= ei->hint_bmap.off) {
 			clu_offset -= ei->hint_bmap.off;
 			clu.dir = ei->hint_bmap.clu;
-		}
-
-		while (clu_offset > 0 && clu.dir != EXFAT_EOF_CLUSTER) {
-			if (exfat_get_next_cluster(sb, &(clu.dir)))
-				return -EIO;
-
-			clu_offset--;
+			clu.size -= ei->hint_bmap.off;
 		}
 	}
 
+	if (exfat_chain_advance(sb, &clu, clu_offset))
+		return -EIO;
+
 	while (clu.dir != EXFAT_EOF_CLUSTER && dentry < max_dentries) {
 		i = dentry & (dentries_per_clu - 1);
 
@@ -160,15 +154,8 @@ static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_ent
 			return 0;
 		}
 
-		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
-			if (--clu.size > 0)
-				clu.dir++;
-			else
-				clu.dir = EXFAT_EOF_CLUSTER;
-		} else {
-			if (exfat_get_next_cluster(sb, &(clu.dir)))
-				return -EIO;
-		}
+		if (exfat_chain_advance(sb, &clu, 1))
+			return -EIO;
 	}
 
 out:
@@ -1085,19 +1072,12 @@ int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
 			step = DIRENT_STEP_FILE;
 		}
 
-		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
-			if (--clu.size > 0)
-				clu.dir++;
-			else
-				clu.dir = EXFAT_EOF_CLUSTER;
-		} else {
-			if (exfat_get_next_cluster(sb, &clu.dir))
-				return -EIO;
+		if (exfat_chain_advance(sb, &clu, 1))
+			return -EIO;
 
-			/* break if the cluster chain includes a loop */
-			if (unlikely(++clu_count > EXFAT_DATA_CLUSTER_COUNT(sbi)))
-				goto not_found;
-		}
+		/* break if the cluster chain includes a loop */
+		if (unlikely(++clu_count > EXFAT_DATA_CLUSTER_COUNT(sbi)))
+			goto not_found;
 	}
 
 not_found:
@@ -1132,14 +1112,7 @@ int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
 	if (!((dentry + 1) & (dentries_per_clu - 1))) {
 		int ret = 0;
 
-		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
-			if (--clu.size > 0)
-				clu.dir++;
-			else
-				clu.dir = EXFAT_EOF_CLUSTER;
-		} else {
-			ret = exfat_get_next_cluster(sb, &clu.dir);
-		}
+		ret = exfat_chain_advance(sb, &clu, 1);
 
 		if (ret || clu.dir == EXFAT_EOF_CLUSTER) {
 			/* just initialized hint_stat */
@@ -1184,20 +1157,12 @@ int exfat_count_dir_entries(struct super_block *sb, struct exfat_chain *p_dir)
 			count++;
 		}
 
-		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
-			if (--clu.size > 0)
-				clu.dir++;
-			else
-				clu.dir = EXFAT_EOF_CLUSTER;
-		} else {
-			if (exfat_get_next_cluster(sb, &(clu.dir)))
-				return -EIO;
-
-			if (unlikely(++clu_count > sbi->used_clusters)) {
-				exfat_fs_error(sb, "FAT or bitmap is corrupted");
-				return -EIO;
-			}
+		if (exfat_chain_advance(sb, &clu, 1))
+			return -EIO;
 
+		if (unlikely(++clu_count > sbi->used_clusters)) {
+			exfat_fs_error(sb, "FAT or bitmap is corrupted");
+			return -EIO;
 		}
 	}
 

fs/exfat/namei.c

@@ -246,15 +246,8 @@ static int exfat_search_empty_slot(struct super_block *sb,
 		i += ret;
 
 		while (i >= dentries_per_clu) {
-			if (clu.flags == ALLOC_NO_FAT_CHAIN) {
-				if (--clu.size > 0)
-					clu.dir++;
-				else
-					clu.dir = EXFAT_EOF_CLUSTER;
-			} else {
-				if (exfat_get_next_cluster(sb, &clu.dir))
-					return -EIO;
-			}
+			if (exfat_chain_advance(sb, &clu, 1))
+				return -EIO;
 
 			i -= dentries_per_clu;
 		}
@@ -925,19 +918,12 @@ static int exfat_check_dir_empty(struct super_block *sb,
 			return -ENOTEMPTY;
 		}
 
-		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
-			if (--clu.size > 0)
-				clu.dir++;
-			else
-				clu.dir = EXFAT_EOF_CLUSTER;
-		} else {
-			if (exfat_get_next_cluster(sb, &(clu.dir)))
-				return -EIO;
+		if (exfat_chain_advance(sb, &clu, 1))
+			return -EIO;
 
-			/* break if the cluster chain includes a loop */
-			if (unlikely(++clu_count > EXFAT_DATA_CLUSTER_COUNT(sbi)))
-				break;
-		}
+		/* break if the cluster chain includes a loop */
+		if (unlikely(++clu_count > EXFAT_DATA_CLUSTER_COUNT(sbi)))
+			break;
 	}
 
 	return 0;