fs: initial qnx6fs addition

Adds support for qnx6fs readonly support to the linux kernel.

* Mount option
  The option mmi_fs can be used to mount Harman Becker/Audi MMI 3G
  HDD qnx6fs filesystems.

* Documentation
  A high level filesystem stucture description can be found in the
  Documentation/filesystems directory. (qnx6.txt)

* Additional features
  - Active (stable) superblock selection
  - Superblock checksum check (enforced)
  - Supports mount of qnx6 filesystems with to host different endianess
  - Automatic endianess detection
  - Longfilename support (with non-enfocing crc check)
  - All blocksizes (512, 1024, 2048 and 4096 supported)

Signed-off-by: Kai Bankett <chaosman@ontika.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 150 insertions, 0 deletions

diff --git a/fs/qnx6/super_mmi.c b/fs/qnx6/super_mmi.c
new file mode 100644
index 000000000000..29c32cba62d6
--- /dev/null
+++ b/fs/qnx6/super_mmi.c
@@ -0,0 +1,150 @@
+/*
+ * QNX6 file system, Linux implementation.
+ *
+ * Version : 1.0.0
+ *
+ * History :
+ *
+ * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include "qnx6.h"
+
+static void qnx6_mmi_copy_sb(struct qnx6_super_block *qsb,
+		struct qnx6_mmi_super_block *sb)
+{
+	qsb->sb_magic = sb->sb_magic;
+	qsb->sb_checksum = sb->sb_checksum;
+	qsb->sb_serial = sb->sb_serial;
+	qsb->sb_blocksize = sb->sb_blocksize;
+	qsb->sb_num_inodes = sb->sb_num_inodes;
+	qsb->sb_free_inodes = sb->sb_free_inodes;
+	qsb->sb_num_blocks = sb->sb_num_blocks;
+	qsb->sb_free_blocks = sb->sb_free_blocks;
+
+	/* the rest of the superblock is the same */
+	memcpy(&qsb->Inode, &sb->Inode, sizeof(sb->Inode));
+	memcpy(&qsb->Bitmap, &sb->Bitmap, sizeof(sb->Bitmap));
+	memcpy(&qsb->Longfile, &sb->Longfile, sizeof(sb->Longfile));
+}
+
+struct qnx6_super_block *qnx6_mmi_fill_super(struct super_block *s, int silent)
+{
+	struct buffer_head *bh1, *bh2 = NULL;
+	struct qnx6_mmi_super_block *sb1, *sb2;
+	struct qnx6_super_block *qsb = NULL;
+	struct qnx6_sb_info *sbi;
+	__u64 offset;
+
+	/* Check the superblock signatures
+	   start with the first superblock */
+	bh1 = sb_bread(s, 0);
+	if (!bh1) {
+		printk(KERN_ERR "qnx6: Unable to read first mmi superblock\n");
+		return NULL;
+	}
+	sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
+	sbi = QNX6_SB(s);
+	if (fs32_to_cpu(sbi, sb1->sb_magic) != QNX6_SUPER_MAGIC) {
+		if (!silent) {
+			printk(KERN_ERR "qnx6: wrong signature (magic) in"
+					" superblock #1.\n");
+			goto out;
+		}
+	}
+
+	/* checksum check - start at byte 8 and end at byte 512 */
+	if (fs32_to_cpu(sbi, sb1->sb_checksum) !=
+				crc32_be(0, (char *)(bh1->b_data + 8), 504)) {
+		printk(KERN_ERR "qnx6: superblock #1 checksum error\n");
+		goto out;
+	}
+
+	/* calculate second superblock blocknumber */
+	offset = fs32_to_cpu(sbi, sb1->sb_num_blocks) + QNX6_SUPERBLOCK_AREA /
+					fs32_to_cpu(sbi, sb1->sb_blocksize);
+
+	/* set new blocksize */
+	if (!sb_set_blocksize(s, fs32_to_cpu(sbi, sb1->sb_blocksize))) {
+		printk(KERN_ERR "qnx6: unable to set blocksize\n");
+		goto out;
+	}
+	/* blocksize invalidates bh - pull it back in */
+	brelse(bh1);
+	bh1 = sb_bread(s, 0);
+	if (!bh1)
+		goto out;
+	sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
+
+	/* read second superblock */
+	bh2 = sb_bread(s, offset);
+	if (!bh2) {
+		printk(KERN_ERR "qnx6: unable to read the second superblock\n");
+		goto out;
+	}
+	sb2 = (struct qnx6_mmi_super_block *)bh2->b_data;
+	if (fs32_to_cpu(sbi, sb2->sb_magic) != QNX6_SUPER_MAGIC) {
+		if (!silent)
+			printk(KERN_ERR "qnx6: wrong signature (magic) in"
+					" superblock #2.\n");
+		goto out;
+	}
+
+	/* checksum check - start at byte 8 and end at byte 512 */
+	if (fs32_to_cpu(sbi, sb2->sb_checksum)
+			!= crc32_be(0, (char *)(bh2->b_data + 8), 504)) {
+		printk(KERN_ERR "qnx6: superblock #1 checksum error\n");
+		goto out;
+	}
+
+	qsb = kmalloc(sizeof(*qsb), GFP_KERNEL);
+	if (!qsb) {
+		printk(KERN_ERR "qnx6: unable to allocate memory.\n");
+		goto out;
+	}
+
+	if (fs64_to_cpu(sbi, sb1->sb_serial) >
+					fs64_to_cpu(sbi, sb2->sb_serial)) {
+		/* superblock #1 active */
+		qnx6_mmi_copy_sb(qsb, sb1);
+#ifdef CONFIG_QNX6FS_DEBUG
+		qnx6_superblock_debug(qsb, s);
+#endif
+		memcpy(bh1->b_data, qsb, sizeof(struct qnx6_super_block));
+
+		sbi->sb_buf = bh1;
+		sbi->sb = (struct qnx6_super_block *)bh1->b_data;
+		brelse(bh2);
+		printk(KERN_INFO "qnx6: superblock #1 active\n");
+	} else {
+		/* superblock #2 active */
+		qnx6_mmi_copy_sb(qsb, sb2);
+#ifdef CONFIG_QNX6FS_DEBUG
+		qnx6_superblock_debug(qsb, s);
+#endif
+		memcpy(bh2->b_data, qsb, sizeof(struct qnx6_super_block));
+
+		sbi->sb_buf = bh2;
+		sbi->sb = (struct qnx6_super_block *)bh2->b_data;
+		brelse(bh1);
+		printk(KERN_INFO "qnx6: superblock #2 active\n");
+	}
+	kfree(qsb);
+
+	/* offset for mmi_fs is just SUPERBLOCK_AREA bytes */
+	sbi->s_blks_off = QNX6_SUPERBLOCK_AREA / s->s_blocksize;
+
+	/* success */
+	return sbi->sb;
+
+out:
+	if (bh1 != NULL)
+		brelse(bh1);
+	if (bh2 != NULL)
+		brelse(bh2);
+	return NULL;
+}