[syslinux:elflink] EXTLINUX: Add sanity check for XFS filesystems

syslinux-bot for Paulo Alcantara pcacjr at zytor.com
Tue Nov 27 12:57:22 PST 2012


Commit-ID:  7997877811d9ce99efed65604bba2bae91332c79
Gitweb:     http://www.syslinux.org/commit/7997877811d9ce99efed65604bba2bae91332c79
Author:     Paulo Alcantara <pcacjr at zytor.com>
AuthorDate: Sat, 28 Jul 2012 19:41:55 -0300
Committer:  Paulo Alcantara <pcacjr at zytor.com>
CommitDate: Sun, 29 Jul 2012 02:15:40 -0300

EXTLINUX: Add sanity check for XFS filesystems

Syslinux won't work on >4 KiB filesystem block sizes since there is no
left space in MBR to determine where to install Syslinux bootsector.

If one is trying to install Syslinux in a XFS partition with a
filesystem block size different of 4 KiB, a proper error will be
returned to the user informing that the current filesystem block size
isn't supported by Syslinux.

Reported-by: Gene Cumm <gene.cumm at gmail.com>
Signed-off-by: Paulo Alcantara <pcacjr at zytor.com>

---
 extlinux/main.c                  | 20 +++++++++++++++++---
 {core/fs/xfs => extlinux}/misc.h |  0
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/extlinux/main.c b/extlinux/main.c
index bbcc8db..d1a800c 100644
--- a/extlinux/main.c
+++ b/extlinux/main.c
@@ -14,7 +14,8 @@
 /*
  * extlinux.c
  *
- * Install the syslinux boot block on an fat, ntfs, ext2/3/4 and btrfs filesystem
+ * Install the syslinux boot block on an fat, ntfs, ext2/3/4, btrfs and xfs
+ * filesystem.
  */
 
 #define  _GNU_SOURCE		/* Enable everything */
@@ -49,6 +50,7 @@
 #include "xfs.h"
 #include "xfs_types.h"
 #include "xfs_sb.h"
+#include "misc.h"
 #include "../version.h"
 #include "syslxint.h"
 #include "syslxcom.h" /* common functions shared with extlinux and syslinux */
@@ -71,7 +73,8 @@
  * we will use the first 0~512 bytes starting from 2048 for the Syslinux
  * boot sector.
  */
-#define XFS_BOOTSECT_OFFSET	4 * SECTOR_SIZE
+#define XFS_BOOTSECT_OFFSET	(4 << SECTOR_SHIFT)
+#define XFS_SUPPORTED_BLOCKSIZE 4096 /* 4 KiB filesystem block size */
 
 /* the btrfs partition first 64K blank area is used to store boot sector and
    boot image, the boot sector is from 0~512, the boot image starts after */
@@ -379,8 +382,19 @@ int install_bootblock(int fd, const char *device)
 	    return 1;
 	}
 
-	if (sb5.sb_magicnum == *(u32 *)XFS_SB_MAGIC)
+	if (sb5.sb_magicnum == *(u32 *)XFS_SB_MAGIC) {
+	    if (be32_to_cpu(sb5.sb_blocksize) != XFS_SUPPORTED_BLOCKSIZE) {
+		fprintf(stderr,
+			"You need to have 4 KiB filesystem block size for "
+			" being able to install Syslinux in your XFS "
+			"partition (because there is no enough space in MBR to "
+			"determine where Syslinux bootsector can be installed "
+			"regardless the filesystem block size)\n");
+		return 1;
+	    }
+
 	    ok = true;
+	}
     }
 
     if (!ok) {
diff --git a/core/fs/xfs/misc.h b/extlinux/misc.h
similarity index 100%
copy from core/fs/xfs/misc.h
copy to extlinux/misc.h


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