[PATCH] disk/fs_uuid.c

[PATCH] disk/fs_uuid.c

[Robert Millan]

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This disk driver allows access to partitions that contain a filesystem with
known UUID via "(UUID=xxxxxxx)" syntax.

The iterator is unimplemented on purpose, because it makes the code smaller
and it isn't useful to waste time inspecting the same devices twice while
scanning for LVM / whatsoever.

Also note that as it currently stands it is highly inefficient.  I can't
understand why;  new UUIDs are searched everytime on each open() call, but
this shouldn't be much of an issue since we have a disk cache in kernel to
make that efficient.  At least, it isn't e.g. for grub_fs_probe() which is
called multiple times.

Even with this efficiency problem, since it doesn't interfere with anything
else I'm inclined to commit it, if nobody objects.

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)

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2008-06-06  Robert Millan  <rmh@aybabtu.com>

	* disk/fs_uuid.c: New file.
	* conf/common.rmk (pkglib_MODULES): Add `fs_uuid.mod'.
	(fs_uuid_mod_SOURCES, fs_uuid_mod_CFLAGS)
	(fs_uuid_mod_LDFLAGS): New variables.
	* include/grub/disk.h (grub_disk_dev_id): Add
	`GRUB_DISK_DEVICE_UUID_ID'.
	* kern/disk.c (grub_disk_dev_iterate): Allow disk devices not to
	implement iterate().

diff -N -x ChangeLog -x configure -x config.h.in -x CVS -x '*~' -x '*.mk' -urp ../grub2/conf/common.rmk ./conf/common.rmk
--- ../grub2/conf/common.rmk	2008-04-13 14:11:33.000000000 +0200
+++ ./conf/common.rmk	2008-06-05 02:09:31.000000000 +0200
@@ -280,7 +280,7 @@ lvm_mod_LDFLAGS = $(COMMON_LDFLAGS)
 # Commands.
 pkglib_MODULES += hello.mod boot.mod terminal.mod ls.mod	\
 	cmp.mod cat.mod help.mod font.mod search.mod		\
-	loopback.mod configfile.mod echo.mod			\
+	loopback.mod fs_uuid.mod configfile.mod echo.mod	\
 	terminfo.mod test.mod blocklist.mod hexdump.mod		\
 	read.mod sleep.mod
 
@@ -344,6 +344,11 @@ loopback_mod_SOURCES = disk/loopback.c
 loopback_mod_CFLAGS = $(COMMON_CFLAGS)
 loopback_mod_LDFLAGS = $(COMMON_LDFLAGS)
 
+# For fs_uuid.mod
+fs_uuid_mod_SOURCES = disk/fs_uuid.c
+fs_uuid_mod_CFLAGS = $(COMMON_CFLAGS)
+fs_uuid_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 # For configfile.mod
 configfile_mod_SOURCES = commands/configfile.c
 configfile_mod_CFLAGS = $(COMMON_CFLAGS)
diff -N -x ChangeLog -x configure -x config.h.in -x CVS -x '*~' -x '*.mk' -urp ../grub2/disk/fs_uuid.c ./disk/fs_uuid.c
--- ../grub2/disk/fs_uuid.c	1970-01-01 01:00:00.000000000 +0100
+++ ./disk/fs_uuid.c	2008-06-05 21:53:38.000000000 +0200
@@ -0,0 +1,137 @@
+/* fs_uuid.c - Access disks by their filesystem UUID.  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2007,2008  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/disk.h>
+#include <grub/dl.h>
+#include <grub/kernel.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/types.h>
+
+#include <grub/fs.h>
+
+static grub_device_t
+search_fs_uuid (const char *key, unsigned long *count)
+{
+  *count = 0;
+  grub_device_t ret = NULL;
+
+  auto int iterate_device (const char *name);
+  int iterate_device (const char *name)
+    {
+      grub_device_t dev;
+
+      dev = grub_device_open (name);
+      if (dev)
+	{
+	  grub_fs_t fs;
+	  
+	  fs = grub_fs_probe (dev);
+	  if (fs && fs->uuid)
+	    {
+	      char *uuid;
+	      
+	      (fs->uuid) (dev, &uuid);
+	      if (grub_errno == GRUB_ERR_NONE && uuid)
+		{
+		  *count++;
+
+		  if (grub_strcmp (uuid, key) == 0)
+		    {
+		      ret = dev;
+		      grub_free (uuid);
+		      return 1;
+		    }
+		  grub_free (uuid);
+		}
+	    }
+	  
+	  grub_device_close (dev);
+	}
+
+      grub_errno = GRUB_ERR_NONE;
+      return 0;
+    }
+  
+  grub_device_iterate (iterate_device);
+  
+  return ret;
+}
+
+static grub_err_t
+grub_fs_uuid_open (const char *name, grub_disk_t disk)
+{
+  grub_device_t dev;
+
+  if (grub_strncmp (name, "UUID=", sizeof ("UUID=")-1))
+    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a UUID virtual volume");
+
+  dev = search_fs_uuid (name + sizeof ("UUID=") - 1, &disk->id);
+  if (! dev)
+    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "no matching UUID found");
+
+  disk->total_sectors = dev->disk->total_sectors;
+  disk->has_partitions = 0;
+  disk->partition = dev->disk->partition;
+  disk->data = dev->disk;
+
+  return GRUB_ERR_NONE;
+}
+
+static void
+grub_fs_uuid_close (grub_disk_t disk __attribute((unused)))
+{
+}
+
+static grub_err_t
+grub_fs_uuid_read (grub_disk_t disk, grub_disk_addr_t sector,
+		   grub_size_t size, char *buf)
+{
+  grub_disk_t parent = disk->data;
+  return parent->dev->read (parent, sector, size, buf);
+}
+
+static grub_err_t
+grub_fs_uuid_write (grub_disk_t disk, grub_disk_addr_t sector,
+		    grub_size_t size, const char *buf)
+{
+  grub_disk_t parent = disk->data;
+  return parent->dev->write (parent, sector, size, buf);
+}
+
+static struct grub_disk_dev grub_fs_uuid_dev =
+  {
+    .name = "fs_uuid",
+    .id = GRUB_DISK_DEVICE_UUID_ID,
+    .open = grub_fs_uuid_open,
+    .close = grub_fs_uuid_close,
+    .read = grub_fs_uuid_read,
+    .write = grub_fs_uuid_write,
+    .next = 0
+  };
+
+GRUB_MOD_INIT(fs_uuid)
+{
+  grub_disk_dev_register (&grub_fs_uuid_dev);
+}
+
+GRUB_MOD_FINI(fs_uuid)
+{
+  grub_disk_dev_unregister (&grub_fs_uuid_dev);
+}
diff -N -x ChangeLog -x configure -x config.h.in -x CVS -x '*~' -x '*.mk' -urp ../grub2/include/grub/disk.h ./include/grub/disk.h
--- ../grub2/include/grub/disk.h	2008-04-26 19:51:01.000000000 +0200
+++ ./include/grub/disk.h	2008-06-05 22:45:34.000000000 +0200
@@ -38,6 +38,7 @@ enum grub_disk_dev_id
     GRUB_DISK_DEVICE_ATA_ID,
     GRUB_DISK_DEVICE_MEMDISK_ID,
     GRUB_DISK_DEVICE_NAND_ID,
+    GRUB_DISK_DEVICE_UUID_ID,
   };
 
 struct grub_disk;
diff -N -x ChangeLog -x configure -x config.h.in -x CVS -x '*~' -x '*.mk' -urp ../grub2/kern/disk.c ./kern/disk.c
--- ../grub2/kern/disk.c	2008-02-08 13:22:51.000000000 +0100
+++ ./kern/disk.c	2008-06-05 22:46:24.000000000 +0200
@@ -202,7 +202,7 @@ grub_disk_dev_iterate (int (*hook) (cons
   grub_disk_dev_t p;
 
   for (p = grub_disk_dev_list; p; p = p->next)
-    if ((p->iterate) (hook))
+    if (p->iterate && (p->iterate) (hook))
       return 1;
 
   return 0;

Re: [PATCH] disk/fs_uuid.c

[Robert Millan]

On Fri, Jun 06, 2008 at 06:23:39PM +0200, Robert Millan wrote:
> 
> Even with this efficiency problem, since it doesn't interfere with anything
> else I'm inclined to commit it, if nobody objects.

Committed.

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)

Re: [PATCH] disk/fs_uuid.c

[Marco Gerards]

Robert Millan <rmh@aybabtu.com> writes:

> This disk driver allows access to partitions that contain a filesystem with
> known UUID via "(UUID=xxxxxxx)" syntax.
>
> The iterator is unimplemented on purpose, because it makes the code smaller
> and it isn't useful to waste time inspecting the same devices twice while
> scanning for LVM / whatsoever.
>
> Also note that as it currently stands it is highly inefficient.  I can't
> understand why;  new UUIDs are searched everytime on each open() call, but
> this shouldn't be much of an issue since we have a disk cache in kernel to
> make that efficient.  At least, it isn't e.g. for grub_fs_probe() which is
> called multiple times.
>
> Even with this efficiency problem, since it doesn't interfere with anything
> else I'm inclined to commit it, if nobody objects.

Why didn't you just extend the search command?  I think that would be
favorable.

--
Marco

Re: [PATCH] disk/fs_uuid.c

[Robert Millan]

On Thu, Jul 03, 2008 at 09:05:54PM +0200, Marco Gerards wrote:
> Robert Millan <rmh@aybabtu.com> writes:
> 
> > This disk driver allows access to partitions that contain a filesystem with
> > known UUID via "(UUID=xxxxxxx)" syntax.
> >
> > The iterator is unimplemented on purpose, because it makes the code smaller
> > and it isn't useful to waste time inspecting the same devices twice while
> > scanning for LVM / whatsoever.
> >
> > Also note that as it currently stands it is highly inefficient.  I can't
> > understand why;  new UUIDs are searched everytime on each open() call, but
> > this shouldn't be much of an issue since we have a disk cache in kernel to
> > make that efficient.  At least, it isn't e.g. for grub_fs_probe() which is
> > called multiple times.
> >
> > Even with this efficiency problem, since it doesn't interfere with anything
> > else I'm inclined to commit it, if nobody objects.
> 
> Why didn't you just extend the search command?  I think that would be
> favorable.

I _did_ extend the search command (before this patch).  The reason for
providing this is basicaly that it makes grub.cfg more readable (and easier
to understand), and can't be used outside the context of scripting (for
example, to set your root/prefix to it, but that would require a patch I
intend to put together soon).

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)

Re: [PATCH] disk/fs_uuid.c

[Robert Millan]

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On Fri, Jul 04, 2008 at 12:50:21AM +0200, Robert Millan wrote:
> 
> I _did_ extend the search command (before this patch).  The reason for
> providing this is basicaly that it makes grub.cfg more readable (and easier
> to understand), and can't be used outside the context of scripting (for
> example, to set your root/prefix to it, but that would require a patch I
> intend to put together soon).

Basicaly like this;  but it'd have to check that UUID is needed rather than
using it unconditionaly, of course.

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)

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Index: include/grub/i386/pc/kernel.h
===================================================================
--- include/grub/i386/pc/kernel.h	(revision 1686)
+++ include/grub/i386/pc/kernel.h	(working copy)
@@ -41,7 +41,7 @@
 #define GRUB_KERNEL_MACHINE_PREFIX		0x20
 
 /* End of the data section. */
-#define GRUB_KERNEL_MACHINE_DATA_END		0x50
+#define GRUB_KERNEL_MACHINE_DATA_END		0x60
 
 /* The size of the first region which won't be compressed.  */
 #define GRUB_KERNEL_MACHINE_RAW_SIZE		(GRUB_KERNEL_MACHINE_DATA_END + 0x450)
Index: util/i386/pc/grub-install.in
===================================================================
--- util/i386/pc/grub-install.in	(revision 1686)
+++ util/i386/pc/grub-install.in	(working copy)
@@ -232,13 +232,13 @@
 devabstraction_module=`$grub_probe --target=abstraction --device ${grub_device}`
 
 if [ "x${devabstraction_module}" = "x" ] ; then
-    prefix_drive=
+    prefix_drive=\(UUID=`$grub_probe --target=fs_uuid --device ${grub_device}`\)
 else
     prefix_drive=`$grub_probe --target=drive --device ${grub_device}`
 fi
 
 # The order in this list is critical.  Be careful when modifiing it.
-modules="$modules $fs_module $partmap_module biosdisk $devabstraction_module"
+modules="$modules $fs_module $partmap_module biosdisk $devabstraction_module fs_uuid"
 
 $grub_mkimage --output=${grubdir}/core.img \
     --prefix=${prefix_drive}`make_system_path_relative_to_its_root ${grubdir}`/ \