zipl: expand interface of disk_get_blocklist_from_file

. expand interface of disk_get_blocklist_from_file() to get
  block pointers for a specific range of data within a file.
. provide a helper function add_component_file_range() to add a
  specific range of data within a file as a boot component.

This will be used by a later patch.

Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Eduard Shishkin <edward6@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zipl/include/disk.h

@@ -90,6 +90,11 @@ struct disk_info {
 	definition_t targetbase;
 };
 
+struct file_range {
+	off_t offset;
+	size_t len;
+};
+
 struct job_target_data;
 
 int disk_get_info(const char* device, struct job_target_data* target,
@@ -119,6 +124,7 @@ int disk_is_zero_block(disk_blockptr_t* block, struct disk_info* info);
 blocknum_t disk_compact_blocklist(disk_blockptr_t* list, blocknum_t count,
 				  struct disk_info* info);
 blocknum_t disk_get_blocklist_from_file(const char* filename,
+					struct file_range *reg,
 					disk_blockptr_t** blocklist,
 					struct disk_info* pinfo);
 int disk_check_subchannel_set(int devno, dev_t device, char* dev_name);

zipl/src/bootmap.c

@@ -17,6 +17,7 @@
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <assert.h>
 
 #include "lib/zt_common.h"
 #include "lib/util_part.h"
@@ -291,10 +292,11 @@ struct component_loc {
 };
 
 static int
-add_component_file(int fd, const char* filename, address_t load_address,
-		   size_t trailer, void *component, int add_files,
-		   struct disk_info* info, struct job_target_data* target,
-		   struct component_loc *location)
+add_component_file_range(int fd, const char *filename, struct file_range *reg,
+			 address_t load_address,
+			 size_t trailer, void *component, int add_files,
+			 struct disk_info *info, struct job_target_data *target,
+			 struct component_loc *location)
 {
 	struct disk_info* file_info;
 	struct component_loc loc;
@@ -306,6 +308,7 @@ add_component_file(int fd, const char* filename, address_t load_address,
 	int rc;
 
 	if (add_files) {
+		assert(reg == NULL); /* not implemented */
 		/* Read file to buffer */
 		rc = misc_read_file(filename, &buffer, &size, 0);
 		if (rc) {
@@ -332,8 +335,8 @@ add_component_file(int fd, const char* filename, address_t load_address,
 			return -1;
 		}
 		/* Get block list from existing file */
-		count = disk_get_blocklist_from_file(filename, &list,
-						     file_info);
+		count = disk_get_blocklist_from_file(filename, reg,
+						     &list, file_info);
 		disk_free_info(file_info);
 		if (count == 0)
 			return -1;
@@ -357,6 +360,17 @@ add_component_file(int fd, const char* filename, address_t load_address,
 	return rc;
 }
 
+static int
+add_component_file(int fd, const char *filename, address_t load_address,
+		   size_t trailer, void *component, int add_files,
+		   struct disk_info *info, struct job_target_data *target,
+		   struct component_loc *location)
+{
+	return add_component_file_range(fd, filename, NULL, load_address,
+					trailer, component, add_files,
+					info, target, location);
+}
+
 static int
 add_component_buffer(int fd, void* buffer, size_t size, component_data data,
 		     void* component, struct disk_info* info,
@@ -834,7 +848,7 @@ add_segment_program(int fd, struct job_segment_data* segment,
 	rc = add_component_file(fd, segment->segment, segment->segment_addr, 0,
 				VOID_ADD(table, offset), add_files, info,
 				target, &comp_loc[0]);
-if (rc) {
+	if (rc) {
 		error_text("Could not add segment file '%s'",
 			   segment->segment);
 		free(table);

zipl/src/disk.c

@@ -23,7 +23,6 @@
 #include <unistd.h>
 #include <linux/fs.h>
 #include <linux/fiemap.h>
-
 #include "lib/util_proc.h"
 #include "lib/util_sys.h"
 
@@ -1064,19 +1063,26 @@ disk_compact_blocklist(disk_blockptr_t* list, blocknum_t count,
 	return last + 1;
 }
 
-
-/* Retrieve a list of pointers to the disk blocks that make up the file
- * specified by FILENAME. Upon success, return the number of blocks and set
- * BLOCKLIST to point to the uncompacted list. INFO provides information
- * about the device which contains the file. Return zero otherwise. */
+/**
+ * Retrieve a list of pointers to the disk blocks that make up the whole
+ * file specified by FILENAME, or only its part specified by REG (if the
+ * last one is not NULL).
+ * Upon success, return the number of blocks and set BLOCKLIST to point to
+ * the uncompacted list. INFO provides information about the device which
+ * contains the file. Return zero otherwise
+ */
 blocknum_t
-disk_get_blocklist_from_file(const char* filename, disk_blockptr_t** blocklist,
+disk_get_blocklist_from_file(const char *filename, struct file_range *reg,
+			     disk_blockptr_t **blocklist,
 			     struct disk_info* info)
 {
 	disk_blockptr_t* list;
 	struct stat stats;
 	int fd;
-	blocknum_t count;
+	off_t off;
+	size_t count;
+	blocknum_t blk_off;
+	blocknum_t blk_count;
 	blocknum_t i;
 	blocknum_t blocknum;
 
@@ -1093,24 +1099,36 @@ disk_get_blocklist_from_file(const char* filename, disk_blockptr_t** blocklist,
 		close (fd);
 		return 0;
 	}
-	/* Get number of blocks */
-	count = ((blocknum_t) stats.st_size +
-			info->phy_block_size - 1) / info->phy_block_size;
-	if (count == 0) {
-		error_reason("Could not read empty file '%s'", filename);
+	if (reg) {
+		off = reg->offset;
+		count = reg->len;
+	} else {
+		off = 0;
+		count = stats.st_size;
+	}
+	if (off >= stats.st_size) {
+		error_reason("Offset %llu is outside the file '%s'",
+			     off, filename);
 		close(fd);
 		return 0;
 	}
+	if (off + count > (size_t)stats.st_size)
+		count = stats.st_size - off;
+
+	blk_off = off / info->phy_block_size;
+	blk_count = ((blocknum_t) count +
+		     info->phy_block_size - 1) / info->phy_block_size;
+
 	list = (disk_blockptr_t *) misc_malloc(sizeof(disk_blockptr_t) *
-					       count);
+					       blk_count);
 	if (list == NULL) {
 		close(fd);
 		return 0;
 	}
-	memset((void *) list, 0, sizeof(disk_blockptr_t) * count);
+	memset((void *) list, 0, sizeof(disk_blockptr_t) * blk_count);
 	/* Build list */
-	for (i=0; i < count; i++) {
-		if (disk_get_blocknum(fd, 0, i, &blocknum, info)) {
+	for (i = 0; i < blk_count; i++) {
+		if (disk_get_blocknum(fd, 0, blk_off + i, &blocknum, info)) {
 			free(list);
 			close(fd);
 			return 0;
@@ -1119,7 +1137,7 @@ disk_get_blocklist_from_file(const char* filename, disk_blockptr_t** blocklist,
 	}
 	close(fd);
 	*blocklist = list;
-	return count;
+	return blk_count;
 }
 
 /* Check whether input device is in subchannel set 0.