udf: refactor udf_current_aext() to handle error

As Jan suggested in links below, refactor udf_current_aext() to
differentiate between error, hit EOF and success, it now takes pointer to
etype to store the extent type, return 1 when getting etype success,
return 0 when hitting EOF and return -errno when err.

Link: https://lore.kernel.org/all/20240912111235.6nr3wuqvktecy3vh@quack3/
Signed-off-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20241001115425.266556-2-zhaomzhao@126.com

fs/udf/inode.c

@@ -1953,6 +1953,7 @@ int udf_setup_indirect_aext(struct inode *inode, udf_pblk_t block,
 	struct extent_position nepos;
 	struct kernel_lb_addr neloc;
 	int ver, adsize;
+	int err = 0;
 
 	if (UDF_I(inode)->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
 		adsize = sizeof(struct short_ad);
@@ -1997,10 +1998,12 @@ int udf_setup_indirect_aext(struct inode *inode, udf_pblk_t block,
 	if (epos->offset + adsize > sb->s_blocksize) {
 		struct kernel_lb_addr cp_loc;
 		uint32_t cp_len;
-		int cp_type;
+		int8_t cp_type;
 
 		epos->offset -= adsize;
-		cp_type = udf_current_aext(inode, epos, &cp_loc, &cp_len, 0);
+		err = udf_current_aext(inode, epos, &cp_loc, &cp_len, &cp_type, 0);
+		if (err <= 0)
+			goto err_out;
 		cp_len |= ((uint32_t)cp_type) << 30;
 
 		__udf_add_aext(inode, &nepos, &cp_loc, cp_len, 1);
@@ -2015,6 +2018,9 @@ int udf_setup_indirect_aext(struct inode *inode, udf_pblk_t block,
 	*epos = nepos;
 
 	return 0;
+err_out:
+	brelse(bh);
+	return err;
 }
 
 /*
@@ -2165,9 +2171,12 @@ int8_t udf_next_aext(struct inode *inode, struct extent_position *epos,
 {
 	int8_t etype;
 	unsigned int indirections = 0;
+	int ret = 0;
 
-	while ((etype = udf_current_aext(inode, epos, eloc, elen, inc)) ==
+	while ((ret = udf_current_aext(inode, epos, eloc, elen,
-	       (EXT_NEXT_EXTENT_ALLOCDESCS >> 30)) {
+				       &etype, inc)) > 0) {
+		if (etype != (EXT_NEXT_EXTENT_ALLOCDESCS >> 30))
+			break;
 		udf_pblk_t block;
 
 		if (++indirections > UDF_MAX_INDIR_EXTS) {
@@ -2188,14 +2197,17 @@ int8_t udf_next_aext(struct inode *inode, struct extent_position *epos,
 		}
 	}
 
-	return etype;
+	return ret > 0 ? etype : -1;
 }
 
-int8_t udf_current_aext(struct inode *inode, struct extent_position *epos,
+/*
-			struct kernel_lb_addr *eloc, uint32_t *elen, int inc)
+ * Returns 1 on success, -errno on error, 0 on hit EOF.
+ */
+int udf_current_aext(struct inode *inode, struct extent_position *epos,
+		     struct kernel_lb_addr *eloc, uint32_t *elen, int8_t *etype,
+		     int inc)
 {
 	int alen;
-	int8_t etype;
 	uint8_t *ptr;
 	struct short_ad *sad;
 	struct long_ad *lad;
@@ -2222,8 +2234,8 @@ int8_t udf_current_aext(struct inode *inode, struct extent_position *epos,
 	case ICBTAG_FLAG_AD_SHORT:
 		sad = udf_get_fileshortad(ptr, alen, &epos->offset, inc);
 		if (!sad)
-			return -1;
+			return 0;
-		etype = le32_to_cpu(sad->extLength) >> 30;
+		*etype = le32_to_cpu(sad->extLength) >> 30;
 		eloc->logicalBlockNum = le32_to_cpu(sad->extPosition);
 		eloc->partitionReferenceNum =
 				iinfo->i_location.partitionReferenceNum;
@@ -2232,17 +2244,17 @@ int8_t udf_current_aext(struct inode *inode, struct extent_position *epos,
 	case ICBTAG_FLAG_AD_LONG:
 		lad = udf_get_filelongad(ptr, alen, &epos->offset, inc);
 		if (!lad)
-			return -1;
+			return 0;
-		etype = le32_to_cpu(lad->extLength) >> 30;
+		*etype = le32_to_cpu(lad->extLength) >> 30;
 		*eloc = lelb_to_cpu(lad->extLocation);
 		*elen = le32_to_cpu(lad->extLength) & UDF_EXTENT_LENGTH_MASK;
 		break;
 	default:
 		udf_debug("alloc_type = %u unsupported\n", iinfo->i_alloc_type);
-		return -1;
+		return -EINVAL;
 	}
 
-	return etype;
+	return 1;
 }
 
 static int udf_insert_aext(struct inode *inode, struct extent_position epos,

fs/udf/truncate.c

@@ -188,6 +188,7 @@ int udf_truncate_extents(struct inode *inode)
 	loff_t byte_offset;
 	int adsize;
 	struct udf_inode_info *iinfo = UDF_I(inode);
+	int ret = 0;
 
 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
 		adsize = sizeof(struct short_ad);
@@ -217,8 +218,8 @@ int udf_truncate_extents(struct inode *inode)
 	else
 		lenalloc -= sizeof(struct allocExtDesc);
 
-	while ((etype = udf_current_aext(inode, &epos, &eloc,
+	while ((ret = udf_current_aext(inode, &epos, &eloc,
-					 &elen, 0)) != -1) {
+				       &elen, &etype, 0)) > 0) {
 		if (etype == (EXT_NEXT_EXTENT_ALLOCDESCS >> 30)) {
 			udf_write_aext(inode, &epos, &neloc, nelen, 0);
 			if (indirect_ext_len) {
@@ -253,6 +254,11 @@ int udf_truncate_extents(struct inode *inode)
 		}
 	}
 
+	if (ret < 0) {
+		brelse(epos.bh);
+		return ret;
+	}
+
 	if (indirect_ext_len) {
 		BUG_ON(!epos.bh);
 		udf_free_blocks(sb, NULL, &epos.block, 0, indirect_ext_len);

fs/udf/udfdecl.h

@@ -171,8 +171,9 @@ extern void udf_write_aext(struct inode *, struct extent_position *,
 extern int8_t udf_delete_aext(struct inode *, struct extent_position);
 extern int8_t udf_next_aext(struct inode *, struct extent_position *,
 			    struct kernel_lb_addr *, uint32_t *, int);
-extern int8_t udf_current_aext(struct inode *, struct extent_position *,
+extern int udf_current_aext(struct inode *inode, struct extent_position *epos,
-			       struct kernel_lb_addr *, uint32_t *, int);
+			    struct kernel_lb_addr *eloc, uint32_t *elen,
+			    int8_t *etype, int inc);
 extern void udf_update_extra_perms(struct inode *inode, umode_t mode);
 
 /* misc.c */