From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: root <root@localhost.localdomain>
Date: Mon, 1 Mar 2021 13:35:34 -0500
Subject: [PATCH] ieee1275: Avoiding many unecessary open/close

This patch aims to change the grub_ofdisk_open and grub_ofdisk_close behaviors. Since some devices (Fibre Channel and NVMe) can have a long time for shutdown notification, we should avoid open and close the disks as much as we can.

So, we are changing how those functions works. The grub_ofdisk_close will take care of just changing the disk element status, by doing a soft close, i.e, the firmware will not be called. On the other hand, the grub_ofdisk_open will take care of closing the current disk opened only if the disk requested in the current call is different from the current one. This close will be responsible to request the firmware to actually close the disk.

Yet, this patch modifies the grub_ofdisk_get_block_size function, avoiding open and close calls inside of it.
---
 grub-core/disk/ieee1275/ofdisk.c | 76 +++++++++++++++++++++++-----------------
 1 file changed, 44 insertions(+), 32 deletions(-)

diff --git a/grub-core/disk/ieee1275/ofdisk.c b/grub-core/disk/ieee1275/ofdisk.c
index 6870b39587d..5fabe365eca 100644
--- a/grub-core/disk/ieee1275/ofdisk.c
+++ b/grub-core/disk/ieee1275/ofdisk.c
@@ -385,6 +385,36 @@ grub_ofdisk_open (const char *name, grub_disk_t disk)
 
   grub_dprintf ("disk", "Opening `%s'.\n", devpath);
 
+  struct ofdisk_hash_ent *op;
+  op = ofdisk_hash_find (devpath);
+  if (!op)
+    op = ofdisk_hash_add (devpath, NULL);
+  else
+    grub_free (devpath);
+  if (!op)
+    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);
@@ -405,30 +435,28 @@ grub_ofdisk_open (const char *name, grub_disk_t disk)
       return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a block device");
     }
 
-  grub_uint32_t block_size = 0;
-  if (grub_ofdisk_get_block_size (devpath, &block_size) == 0)
-    {
-      for (disk->log_sector_size = 0;
-           (1U << disk->log_sector_size) < block_size;
-           disk->log_sector_size++);
-    }
-
+  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);
-    else
-      grub_free (devpath);
-    if (!op)
-      return grub_errno;
     disk->id = (unsigned long) op;
     disk->data = op->open_path;
+
+    grub_uint32_t block_size = 0;
+    if (grub_ofdisk_get_block_size (devpath, &block_size) == 0)
+      {
+        for (disk->log_sector_size = 0;
+             (1U << disk->log_sector_size) < block_size;
+             disk->log_sector_size++);
+      }
+    else
+      {
+        grub_free (devpath);
+        return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "error getting block size");
+      }
   }
 
   return 0;
@@ -437,13 +465,6 @@ 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;
 }
 
@@ -602,15 +623,6 @@ 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");
 
   INIT_IEEE1275_COMMON (&args_ieee1275.common, "call-method", 2, 2);
   args_ieee1275.method = (grub_ieee1275_cell_t) "block-size";