The code currently mounts an HFS+ volume read-only (unless given the

"force" mount option) if it detects that the HFS+ volume has a journal. 
The code was unconditionally assuming that the volume had a jounal if the
journal attribute was set in the volume header.  However, the volume also
has to have a non-zero journal info block to actually have a journal.

In this patch, I refactored the journal detection into a function since
the logic is used twice.  The journal detection also uses the better logic
to determine if there is a journal.
Signed-off-by: Warren Turkal <wt@penguintechs.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/hfsplus/super.c

@@ -21,6 +21,12 @@ static void hfsplus_destroy_inode(struct inode *inode);
 
 #include "hfsplus_fs.h"
 
+static bool hfsplus_vol_has_journal(struct hfsplus_vh *vhdr)
+{
+	return (vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_JOURNALED) &&
+				vhdr->journal_info_block);
+}
+
 struct inode *hfsplus_iget(struct super_block *sb, unsigned long ino)
 {
 	struct hfs_find_data fd;
@@ -279,7 +285,7 @@ static int hfsplus_remount(struct super_block *sb, int *flags, char *data)
 			printk(KERN_WARNING "hfs: filesystem is marked locked, leaving read-only.\n");
 			sb->s_flags |= MS_RDONLY;
 			*flags |= MS_RDONLY;
-		} else if (vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_JOURNALED)) {
+		} else if (hfsplus_vol_has_journal(vhdr)) {
 			printk(KERN_WARNING "hfs: filesystem is marked journaled, leaving read-only.\n");
 			sb->s_flags |= MS_RDONLY;
 			*flags |= MS_RDONLY;
@@ -376,7 +382,7 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
 	} else if (vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_SOFTLOCK)) {
 		printk(KERN_WARNING "hfs: Filesystem is marked locked, mounting read-only.\n");
 		sb->s_flags |= MS_RDONLY;
-	} else if ((vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_JOURNALED)) && !(sb->s_flags & MS_RDONLY)) {
+	} else if (hfsplus_vol_has_journal(vhdr) && !(sb->s_flags & MS_RDONLY)) {
 		printk(KERN_WARNING "hfs: write access to a journaled filesystem is not supported, "
 		       "use the force option at your own risk, mounting read-only.\n");
 		sb->s_flags |= MS_RDONLY;