grub2/0001-grub-core-modify-sector-by-sysfs-as-disk-sector.patch

From 1eee02bbf2c11167e94f424846ce1de0b6e7fa8e Mon Sep 17 00:00:00 2001
From: Mukesh Kumar Chaurasiya <mchauras@linux.vnet.ibm.com>
Date: Fri, 3 Feb 2023 10:10:43 +0530
Subject: [PATCH] grub-core: modify sector by sysfs as disk sector

The disk sector size provided by sysfs file system considers the
sector size of 512 irrespective of disk sector size, Thus
causing the read by grub to an incorrect offset from what was
originally intended.

Considering the 512 sector size of sysfs data the actual sector
needs to be modified corresponding to disk sector size.

Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.vnet.ibm.com>
---
 grub-core/osdep/linux/hostdisk.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

--- a/grub-core/osdep/linux/hostdisk.c
+++ b/grub-core/osdep/linux/hostdisk.c
@@ -199,8 +199,15 @@
 
 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
 
+static inline grub_disk_addr_t
+transform_sector (grub_disk_t disk, grub_disk_addr_t sector)
+{
+  return sector >> (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
+}
+
 static int
-grub_hostdisk_linux_find_partition (char *dev, grub_disk_addr_t sector)
+grub_hostdisk_linux_find_partition (const grub_disk_t disk, char *dev,
+                                    grub_disk_addr_t sector)
 {
   size_t len = strlen (dev);
   const char *format;
@@ -265,7 +272,8 @@
       if (fstat (fd, &st) < 0
 	  || !grub_util_device_is_mapped_stat (&st)
 	  || !grub_util_get_dm_node_linear_info (st.st_rdev, 0, 0, &start))
-	start = grub_util_find_partition_start_os (real_dev);
+	start = transform_sector (disk,
+                                 grub_util_find_partition_start_os (real_dev));
       /* We don't care about errors here.  */
       grub_errno = GRUB_ERR_NONE;
 
@@ -346,7 +354,8 @@
 	&& strncmp (dev, "/dev/", 5) == 0)
       {
 	if (sector >= part_start)
-	  is_partition = grub_hostdisk_linux_find_partition (dev, part_start);
+	  is_partition = grub_hostdisk_linux_find_partition (disk, dev,
+                                                            part_start);
 	else
 	  *max = part_start - sector;
       }