Re: [PATCH v3 2/6] ieee1275/powerpc: enables device mapper discovery

[Vladimir 'phcoder' Serbinenko]

2 problems:

* How does dm device ends up on ofpathname? It should be handled by grub internal logic in most cases and not end up in of-specific paths

* Why not use existing devmapper functions already present in codebase?

Le jeu. 6 juin 2024, 14:40, Avnish Chouhan <avnish@linux.ibm.com> a écrit :

This patch enables the device mapper discovery on ofpath.c. Currently,
when we are dealing with a device like /dev/dm-* the ofpath returns null
since there is no function implemented to handle this case.

This patch implements a function that will look into /sys/block/dm-*
devices and search recursively inside slaves directory to find the root
disk.

Signed-off-by: Diego Domingos <diegodo@br.ibm.com>
Signed-off-by: Avnish Chouhan <avnish@linux.ibm.com>
---
 grub-core/osdep/linux/ofpath.c | 64 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/grub-core/osdep/linux/ofpath.c b/grub-core/osdep/linux/ofpath.c
index 0f5d54e9f2d..cc849d9c94c 100644
--- a/grub-core/osdep/linux/ofpath.c
+++ b/grub-core/osdep/linux/ofpath.c
@@ -37,6 +37,7 @@
 #include <fcntl.h>
 #include <errno.h>
 #include <ctype.h>
+#include <dirent.h>

 #ifdef __sparc__
 typedef enum
@@ -755,13 +756,74 @@ strip_trailing_digits (const char *p)
   return new;
 }

+static char *
+get_slave_from_dm (const char * device)
+{
+  char *curr_device, *tmp;
+  char *directory;
+  char *ret = NULL;
+  directory = grub_strdup (device);
+  tmp = get_basename (directory);
+  curr_device = grub_strdup (tmp);
+  *tmp = '\0';
+
+  /* Recursively check for slaves devices so we can find the root device */
+  while ((curr_device[0] == 'd') && (curr_device[1] == 'm') && (curr_device[2] == '-'))
+    {
+      DIR *dp;
+      struct dirent *ep;
+      char* device_path;
+      device_path = grub_xasprintf ("/sys/block/%s/slaves", curr_device);
+      dp = opendir (device_path);
+
+      if (dp != NULL)
+        {
+          ep = readdir (dp);
+
+          while (ep != NULL)
+            {
+              /* avoid some system directories */
+              if (!strcmp(ep->d_name,"."))
+                goto next_dir;
+              if (!strcmp(ep->d_name,".."))
+                goto next_dir;
+
+              free (curr_device);
+              free (ret);
+              curr_device = grub_strdup (ep->d_name);
+              ret = grub_xasprintf ("%s%s", directory, curr_device);
+              break;
+
+              next_dir:
+              ep = readdir (dp);
+              continue;
+            }
+          closedir (dp);
+        }
+      else
+        grub_util_warn (_("cannot open directory `%s'"), device_path);
+      free (device_path);
+    }
+  free (directory);
+  free (curr_device);
+
+  return ret;
+}
+
 char *
 grub_util_devname_to_ofpath (const char *sys_devname)
 {
-  char *name_buf, *device, *devnode, *devicenode, *ofpath;
+  char *name_buf, *device, *devnode, *devicenode, *ofpath, *realname;

   name_buf = xrealpath (sys_devname);

+  realname = get_slave_from_dm (name_buf);
+  if (realname)
+    {
+      free (name_buf);
+      name_buf = realname;
+    }
+
   device = get_basename (name_buf);
   devnode = strip_trailing_digits (name_buf);
   devicenode = strip_trailing_digits (device);

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