From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Diego Domingos <diegodo@br.ibm.com>
Date: Mon, 14 Dec 2020 17:42:45 +0100
Subject: [PATCH] ieee1275: Avoiding many unecessary open/close

Signed-off-by: Diego Domingos <diegodo@br.ibm.com>
---
 grub-core/disk/ieee1275/ofdisk.c | 64 ++++++++++++++++++++++------------------
 1 file changed, 35 insertions(+), 29 deletions(-)

diff --git a/grub-core/disk/ieee1275/ofdisk.c b/grub-core/disk/ieee1275/ofdisk.c
index d887d4b6e..f3a6ecd79 100644
--- a/grub-core/disk/ieee1275/ofdisk.c
+++ b/grub-core/disk/ieee1275/ofdisk.c
@@ -44,7 +44,7 @@ struct ofdisk_hash_ent
 };
 
 static grub_err_t
-grub_ofdisk_get_block_size (const char *device, grub_uint32_t *block_size,
+grub_ofdisk_get_block_size (grub_uint32_t *block_size,
 			    struct ofdisk_hash_ent *op);
 
 #define OFDISK_HASH_SZ	8
@@ -461,6 +461,7 @@ grub_ofdisk_open (const char *name, grub_disk_t disk)
   grub_ssize_t actual;
   grub_uint32_t block_size = 0;
   grub_err_t err;
+  struct ofdisk_hash_ent *op;
 
   if (grub_strncmp (name, "ieee1275/", sizeof ("ieee1275/") - 1) != 0)
       return grub_error (GRUB_ERR_UNKNOWN_DEVICE,
@@ -471,6 +472,35 @@ grub_ofdisk_open (const char *name, grub_disk_t disk)
 
   grub_dprintf ("disk", "Opening `%s'.\n", devpath);
 
+  op = ofdisk_hash_find (devpath);
+  if (!op)
+    op = ofdisk_hash_add (devpath, NULL);
+  if (!op)
+    {
+      grub_free (devpath);
+      return grub_errno;
+    }
+
+  /* Check if the call to open is the same to the last disk already opened */
+  if (last_devpath && !grub_strcmp(op->open_path,last_devpath))
+  {
+      goto finish;
+  }
+
+ /* If not, we need to close the previous disk and open the new one */
+  else {
+    if (last_ihandle){
+        grub_ieee1275_close (last_ihandle);
+    }
+    last_ihandle = 0;
+    last_devpath = NULL;
+
+    grub_ieee1275_open (op->open_path, &last_ihandle);
+    if (! last_ihandle)
+      return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "can't open device");
+    last_devpath = op->open_path;
+  }
+
   if (grub_ieee1275_finddevice (devpath, &dev))
     {
       grub_free (devpath);
@@ -491,25 +521,18 @@ grub_ofdisk_open (const char *name, grub_disk_t disk)
       return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a block device");
     }
 
+
+  finish:
   /* XXX: There is no property to read the number of blocks.  There
      should be a property `#blocks', but it is not there.  Perhaps it
      is possible to use seek for this.  */
   disk->total_sectors = GRUB_DISK_SIZE_UNKNOWN;
 
   {
-    struct ofdisk_hash_ent *op;
-    op = ofdisk_hash_find (devpath);
-    if (!op)
-      op = ofdisk_hash_add (devpath, NULL);
-    if (!op)
-      {
-        grub_free (devpath);
-        return grub_errno;
-      }
     disk->id = (unsigned long) op;
     disk->data = op->open_path;
 
-    err = grub_ofdisk_get_block_size (devpath, &block_size, op);
+    err = grub_ofdisk_get_block_size (&block_size, op);
     if (err)
       {
         grub_free (devpath);
@@ -532,13 +555,6 @@ grub_ofdisk_open (const char *name, grub_disk_t disk)
 static void
 grub_ofdisk_close (grub_disk_t disk)
 {
-  if (disk->data == last_devpath)
-    {
-      if (last_ihandle)
-	grub_ieee1275_close (last_ihandle);
-      last_ihandle = 0;
-      last_devpath = NULL;
-    }
   disk->data = 0;
 }
 
@@ -685,7 +701,7 @@ grub_ofdisk_init (void)
 }
 
 static grub_err_t
-grub_ofdisk_get_block_size (const char *device, grub_uint32_t *block_size,
+grub_ofdisk_get_block_size (grub_uint32_t *block_size,
 			    struct ofdisk_hash_ent *op)
 {
   struct size_args_ieee1275
@@ -698,16 +714,6 @@ grub_ofdisk_get_block_size (const char *device, grub_uint32_t *block_size,
       grub_ieee1275_cell_t size2;
     } args_ieee1275;
 
-  if (last_ihandle)
-    grub_ieee1275_close (last_ihandle);
-
-  last_ihandle = 0;
-  last_devpath = NULL;
-
-  grub_ieee1275_open (device, &last_ihandle);
-  if (! last_ihandle)
-    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "can't open device");
-
   *block_size = 0;
 
   if (op->block_size_fails >= 2)
