[PATCH v2 0/2] linux: use stat instead of udevadm for partition lookup

[PATCH v2 0/2] linux: use stat instead of udevadm for partition lookup

[Petr Vorel]

Hi,

changes v1->v2:
* remove udevadm fallback from sysfs_partition_path() as we agreed it
  does not bring any advantage over plain stat() call.
* improve comment in major.h
* improve commit message
* adjust comment in configure.ac
* fix code style (spaces)

Jeff Mahoney (1):
  linux/hostdisk: use stat() instead of udevadm for partition lookup

Petr Vorel (1):
  osdep: Introduce major.h and use it

 configure.ac                         |  2 +-
 grub-core/osdep/devmapper/getroot.c  |  7 +---
 grub-core/osdep/devmapper/hostdisk.c |  7 +---
 grub-core/osdep/linux/getroot.c      |  7 +---
 grub-core/osdep/linux/hostdisk.c     | 52 ++++------------------------
 grub-core/osdep/unix/getroot.c       |  7 +---
 include/grub/osdep/major.h           | 30 ++++++++++++++++
 7 files changed, 41 insertions(+), 71 deletions(-)
 create mode 100644 include/grub/osdep/major.h

-- 
2.32.0

[PATCH v2 1/2] osdep: Introduce major.h and use it

[Petr Vorel]

to factor out fix for glibc 2.25 introduced in 7a5b301e3 ("build: Use
AC_HEADER_MAJOR to find device macros").

NOTE: Once glibc 2.25 is old enough and this fix is not needed also
AC_HEADER_MAJOR in configure.ac should be removed.

Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
changes v1->v2:
* improve comment in major.h
* adjust comment in configure.ac
* improve commit message

 configure.ac                         |  2 +-
 grub-core/osdep/devmapper/getroot.c  |  7 +------
 grub-core/osdep/devmapper/hostdisk.c |  7 +------
 grub-core/osdep/linux/getroot.c      |  7 +------
 grub-core/osdep/unix/getroot.c       |  7 +------
 include/grub/osdep/major.h           | 30 ++++++++++++++++++++++++++++
 6 files changed, 35 insertions(+), 25 deletions(-)
 create mode 100644 include/grub/osdep/major.h

diff --git a/configure.ac b/configure.ac
index b025e1e84..09ba4ba2b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -424,7 +424,7 @@ AC_CHECK_HEADERS(sys/param.h sys/mount.h sys/mnttab.h limits.h)
 
 # glibc 2.25 still includes sys/sysmacros.h in sys/types.h but emits deprecation
 # warning which causes compilation failure later with -Werror. So use -Werror here
-# as well to force proper sys/sysmacros.h detection.
+# as well to force proper sys/sysmacros.h detection. Used in major.h.
 SAVED_CFLAGS="$CFLAGS"
 CFLAGS="$HOST_CFLAGS -Werror"
 AC_HEADER_MAJOR
diff --git a/grub-core/osdep/devmapper/getroot.c b/grub-core/osdep/devmapper/getroot.c
index a13a39c96..9ba5c9865 100644
--- a/grub-core/osdep/devmapper/getroot.c
+++ b/grub-core/osdep/devmapper/getroot.c
@@ -40,12 +40,7 @@
 #include <limits.h>
 #endif
 
-#if defined(MAJOR_IN_MKDEV)
-#include <sys/mkdev.h>
-#elif defined(MAJOR_IN_SYSMACROS)
-#include <sys/sysmacros.h>
-#endif
-
+#include <grub/osdep/major.h>
 #include <libdevmapper.h>
 
 #include <grub/types.h>
diff --git a/grub-core/osdep/devmapper/hostdisk.c b/grub-core/osdep/devmapper/hostdisk.c
index a8afc0c94..c8053728b 100644
--- a/grub-core/osdep/devmapper/hostdisk.c
+++ b/grub-core/osdep/devmapper/hostdisk.c
@@ -11,6 +11,7 @@
 #include <grub/misc.h>
 #include <grub/i18n.h>
 #include <grub/list.h>
+#include <grub/osdep/major.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -24,12 +25,6 @@
 #include <errno.h>
 #include <limits.h>
 
-#if defined(MAJOR_IN_MKDEV)
-#include <sys/mkdev.h>
-#elif defined(MAJOR_IN_SYSMACROS)
-#include <sys/sysmacros.h>
-#endif
-
 #ifdef HAVE_DEVICE_MAPPER
 # include <libdevmapper.h>
 
diff --git a/grub-core/osdep/linux/getroot.c b/grub-core/osdep/linux/getroot.c
index 001b818fe..cd588588e 100644
--- a/grub-core/osdep/linux/getroot.c
+++ b/grub-core/osdep/linux/getroot.c
@@ -35,12 +35,7 @@
 #include <limits.h>
 #endif
 
-#if defined(MAJOR_IN_MKDEV)
-#include <sys/mkdev.h>
-#elif defined(MAJOR_IN_SYSMACROS)
-#include <sys/sysmacros.h>
-#endif
-
+#include <grub/osdep/major.h>
 #include <grub/types.h>
 #include <sys/ioctl.h>         /* ioctl */
 #include <sys/mount.h>
diff --git a/grub-core/osdep/unix/getroot.c b/grub-core/osdep/unix/getroot.c
index 46d7116c6..74f69116d 100644
--- a/grub-core/osdep/unix/getroot.c
+++ b/grub-core/osdep/unix/getroot.c
@@ -51,12 +51,7 @@
 #endif /* ! FLOPPY_MAJOR */
 #endif
 
-#include <sys/types.h>
-#if defined(MAJOR_IN_MKDEV)
-#include <sys/mkdev.h>
-#elif defined(MAJOR_IN_SYSMACROS)
-#include <sys/sysmacros.h>
-#endif
+#include <grub/osdep/major.h>
 
 #if defined(HAVE_LIBZFS) && defined(HAVE_LIBNVPAIR)
 # include <grub/util/libzfs.h>
diff --git a/include/grub/osdep/major.h b/include/grub/osdep/major.h
new file mode 100644
index 000000000..cb468351d
--- /dev/null
+++ b/include/grub/osdep/major.h
@@ -0,0 +1,30 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2021  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/>.
+ */
+
+/*
+ * Fix for glibc 2.25 which is deprecating the namespace pollution of
+ * sys/types.h injecting major(), minor(), and makedev() into the compilation
+ * environment.
+*/
+
+#include <sys/types.h>
+#ifdef MAJOR_IN_MKDEV
+# include <sys/mkdev.h>
+#elif defined(MAJOR_IN_SYSMACROS)
+# include <sys/sysmacros.h>
+#endif
-- 
2.32.0

[PATCH v2 2/2] linux/hostdisk: use stat() instead of udevadm for partition lookup

[Petr Vorel]

From: Jeff Mahoney <jeffm@suse.com>

sysfs_partition_path() calls udevadm to resolve the sysfs path for
a block device. That can be accomplished by stating the device node
and using the major/minor to follow the symlinks in /sys/dev/block/.

This cuts the execution time of grub-mkconfig to somewhere near 55% on
system without LVM (which uses libdevmapper instead sysfs_partition_path()).

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
[ pvorel: remove udevadm fallback as it does not help us more than
calling stat() directly; include <grub/osdep/major.h>, update commit
message. ]
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
changes v1->v2:
* remove udevadm fallback from sysfs_partition_path() as we agreed it
  does not bring any advantage over plain stat() call.
* improve commit message
* fix code style (spaces)

 grub-core/osdep/linux/hostdisk.c | 52 ++++----------------------------
 1 file changed, 6 insertions(+), 46 deletions(-)

diff --git a/grub-core/osdep/linux/hostdisk.c b/grub-core/osdep/linux/hostdisk.c
index da62f924e..d3326d095 100644
--- a/grub-core/osdep/linux/hostdisk.c
+++ b/grub-core/osdep/linux/hostdisk.c
@@ -31,6 +31,7 @@
 #include <grub/misc.h>
 #include <grub/i18n.h>
 #include <grub/list.h>
+#include <grub/osdep/major.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -98,54 +99,13 @@ grub_util_get_fd_size_os (grub_util_fd_t fd, const char *name, unsigned *log_sec
 static char *
 sysfs_partition_path (const char *dev, const char *entry)
 {
-  const char *argv[7];
-  int fd;
-  pid_t pid;
-  FILE *udevadm;
-  char *buf = NULL;
-  size_t len = 0;
-  char *path = NULL;
-
-  argv[0] = "udevadm";
-  argv[1] = "info";
-  argv[2] = "--query";
-  argv[3] = "path";
-  argv[4] = "--name";
-  argv[5] = dev;
-  argv[6] = NULL;
-
-  pid = grub_util_exec_pipe (argv, &fd);
-
-  if (!pid)
-    return NULL;
-
-  /* Parent.  Read udevadm's output.  */
-  udevadm = fdopen (fd, "r");
-  if (!udevadm)
-    {
-      grub_util_warn (_("Unable to open stream from %s: %s"),
-		      "udevadm", strerror (errno));
-      close (fd);
-      goto out;
-    }
-
-  if (getline (&buf, &len, udevadm) > 0)
-    {
-      char *newline;
-
-      newline = strchr (buf, '\n');
-      if (newline)
-	*newline = '\0';
-      path = xasprintf ("/sys%s/%s", buf, entry);
-    }
+  struct stat st;
 
-out:
-  if (udevadm)
-    fclose (udevadm);
-  waitpid (pid, NULL, 0);
-  free (buf);
+  if (stat (dev, &st) == 0 && S_ISBLK (st.st_mode))
+    return xasprintf ("/sys/dev/block/%u:%u/%s",
+		      major (st.st_rdev), minor (st.st_rdev), entry);
 
-  return path;
+  return NULL;
 }
 
 static int
-- 
2.32.0

Re: [PATCH v2 1/2] osdep: Introduce major.h and use it

[Daniel Kiper]

On Thu, Jul 15, 2021 at 05:35:27PM +0200, Petr Vorel wrote:
> to factor out fix for glibc 2.25 introduced in 7a5b301e3 ("build: Use
> AC_HEADER_MAJOR to find device macros").
>
> NOTE: Once glibc 2.25 is old enough and this fix is not needed also
> AC_HEADER_MAJOR in configure.ac should be removed.
>
> Signed-off-by: Petr Vorel <pvorel@suse.cz>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Daniel

Re: [PATCH v2 2/2] linux/hostdisk: use stat() instead of udevadm for partition lookup

[Daniel Kiper]

On Thu, Jul 15, 2021 at 05:35:28PM +0200, Petr Vorel wrote:
> From: Jeff Mahoney <jeffm@suse.com>
>
> sysfs_partition_path() calls udevadm to resolve the sysfs path for
> a block device. That can be accomplished by stating the device node
> and using the major/minor to follow the symlinks in /sys/dev/block/.
>
> This cuts the execution time of grub-mkconfig to somewhere near 55% on
> system without LVM (which uses libdevmapper instead sysfs_partition_path()).
>
> Signed-off-by: Jeff Mahoney <jeffm@suse.com>
> [ pvorel: remove udevadm fallback as it does not help us more than
> calling stat() directly; include <grub/osdep/major.h>, update commit
> message. ]
> Signed-off-by: Petr Vorel <pvorel@suse.cz>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Daniel