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, 291 insertions, 0 deletions

diff --git a/fs/qnx6/dir.c b/fs/qnx6/dir.c
new file mode 100644
index 0000000..dc59735
--- /dev/null
+++ b/fs/qnx6/dir.c
@@ -0,0 +1,291 @@
+/*
+ * QNX6 file system, Linux implementation.
+ *
+ * Version : 1.0.0
+ *
+ * History :
+ *
+ * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
+ * 16-02-2012 pagemap extension by Al Viro
+ *
+ */
+
+#include "qnx6.h"
+
+static unsigned qnx6_lfile_checksum(char *name, unsigned size)
+{
+	unsigned crc = 0;
+	char *end = name + size;
+	while (name < end) {
+		crc = ((crc >> 1) + *(name++)) ^
+			((crc & 0x00000001) ? 0x80000000 : 0);
+	}
+	return crc;
+}
+
+static struct page *qnx6_get_page(struct inode *dir, unsigned long n)
+{
+	struct address_space *mapping = dir->i_mapping;
+	struct page *page = read_mapping_page(mapping, n, NULL);
+	if (!IS_ERR(page))
+		kmap(page);
+	return page;
+}
+
+static inline unsigned long dir_pages(struct inode *inode)
+{
+	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
+}
+
+static unsigned last_entry(struct inode *inode, unsigned long page_nr)
+{
+	unsigned long last_byte = inode->i_size;
+	last_byte -= page_nr << PAGE_CACHE_SHIFT;
+	if (last_byte > PAGE_CACHE_SIZE)
+		last_byte = PAGE_CACHE_SIZE;
+	return last_byte / QNX6_DIR_ENTRY_SIZE;
+}
+
+static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
+					 struct qnx6_long_dir_entry *de,
+					 struct page **p)
+{
+	struct qnx6_sb_info *sbi = QNX6_SB(sb);
+	u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
+	u32 n = s >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits); /* in pages */
+	/* within page */
+	u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_CACHE_MASK;
+	struct address_space *mapping = sbi->longfile->i_mapping;
+	struct page *page = read_mapping_page(mapping, n, NULL);
+	if (IS_ERR(page))
+		return ERR_CAST(page);
+	kmap(*p = page);
+	return (struct qnx6_long_filename *)(page_address(page) + offs);
+}
+
+static int qnx6_dir_longfilename(struct inode *inode,
+			struct qnx6_long_dir_entry *de,
+			void *dirent, loff_t pos,
+			unsigned de_inode, filldir_t filldir)
+{
+	struct qnx6_long_filename *lf;
+	struct super_block *s = inode->i_sb;
+	struct qnx6_sb_info *sbi = QNX6_SB(s);
+	struct page *page;
+	int lf_size;
+
+	if (de->de_size != 0xff) {
+		/* error - long filename entries always have size 0xff
+		   in direntry */
+		printk(KERN_ERR "qnx6: invalid direntry size (%i).\n",
+				de->de_size);
+		return 0;
+	}
+	lf = qnx6_longname(s, de, &page);
+	if (IS_ERR(lf)) {
+		printk(KERN_ERR "qnx6:Error reading longname\n");
+		return 0;
+	}
+
+	lf_size = fs16_to_cpu(sbi, lf->lf_size);
+
+	if (lf_size > QNX6_LONG_NAME_MAX) {
+		QNX6DEBUG((KERN_INFO "file %s\n", lf->lf_fname));
+		printk(KERN_ERR "qnx6:Filename too long (%i)\n", lf_size);
+		qnx6_put_page(page);
+		return 0;
+	}
+
+	/* calc & validate longfilename checksum
+	   mmi 3g filesystem does not have that checksum */
+	if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
+			qnx6_lfile_checksum(lf->lf_fname, lf_size))
+		printk(KERN_INFO "qnx6: long filename checksum error.\n");
+
+	QNX6DEBUG((KERN_INFO "qnx6_readdir:%.*s inode:%u\n",
+					lf_size, lf->lf_fname, de_inode));
+	if (filldir(dirent, lf->lf_fname, lf_size, pos, de_inode,
+			DT_UNKNOWN) < 0) {
+		qnx6_put_page(page);
+		return 0;
+	}
+
+	qnx6_put_page(page);
+	/* success */
+	return 1;
+}
+
+static int qnx6_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+	struct inode *inode = filp->f_path.dentry->d_inode;
+	struct super_block *s = inode->i_sb;
+	struct qnx6_sb_info *sbi = QNX6_SB(s);
+	loff_t pos = filp->f_pos & (QNX6_DIR_ENTRY_SIZE - 1);
+	unsigned long npages = dir_pages(inode);
+	unsigned long n = pos >> PAGE_CACHE_SHIFT;
+	unsigned start = (pos & ~PAGE_CACHE_MASK) / QNX6_DIR_ENTRY_SIZE;
+	bool done = false;
+
+	if (filp->f_pos >= inode->i_size)
+		return 0;
+
+	for ( ; !done && n < npages; n++, start = 0) {
+		struct page *page = qnx6_get_page(inode, n);
+		int limit = last_entry(inode, n);
+		struct qnx6_dir_entry *de;
+		int i = start;
+
+		if (IS_ERR(page)) {
+			printk(KERN_ERR "qnx6_readdir: read failed\n");
+			filp->f_pos = (n + 1) << PAGE_CACHE_SHIFT;
+			return PTR_ERR(page);
+		}
+		de = ((struct qnx6_dir_entry *)page_address(page)) + start;
+		for (; i < limit; i++, de++, pos += QNX6_DIR_ENTRY_SIZE) {
+			int size = de->de_size;
+			u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
+
+			if (!no_inode || !size)
+				continue;
+
+			if (size > QNX6_SHORT_NAME_MAX) {
+				/* long filename detected
+				   get the filename from long filename
+				   structure / block */
+				if (!qnx6_dir_longfilename(inode,
+					(struct qnx6_long_dir_entry *)de,
+					dirent, pos, no_inode,
+					filldir)) {
+					done = true;
+					break;
+				}
+			} else {
+				QNX6DEBUG((KERN_INFO "qnx6_readdir:%.*s"
+				   " inode:%u\n", size, de->de_fname,
+							no_inode));
+				if (filldir(dirent, de->de_fname, size,
+				      pos, no_inode, DT_UNKNOWN)
+					< 0) {
+					done = true;
+					break;
+				}
+			}
+		}
+		qnx6_put_page(page);
+	}
+	filp->f_pos = pos;
+	return 0;
+}
+
+/*
+ * check if the long filename is correct.
+ */
+static unsigned qnx6_long_match(int len, const char *name,
+			struct qnx6_long_dir_entry *de, struct inode *dir)
+{
+	struct super_block *s = dir->i_sb;
+	struct qnx6_sb_info *sbi = QNX6_SB(s);
+	struct page *page;
+	int thislen;
+	struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
+
+	if (IS_ERR(lf))
+		return 0;
+
+	thislen = fs16_to_cpu(sbi, lf->lf_size);
+	if (len != thislen) {
+		qnx6_put_page(page);
+		return 0;
+	}
+	if (memcmp(name, lf->lf_fname, len) == 0) {
+		qnx6_put_page(page);
+		return fs32_to_cpu(sbi, de->de_inode);
+	}
+	qnx6_put_page(page);
+	return 0;
+}
+
+/*
+ * check if the filename is correct.
+ */
+static unsigned qnx6_match(struct super_block *s, int len, const char *name,
+			struct qnx6_dir_entry *de)
+{
+	struct qnx6_sb_info *sbi = QNX6_SB(s);
+	if (memcmp(name, de->de_fname, len) == 0)
+		return fs32_to_cpu(sbi, de->de_inode);
+	return 0;
+}
+
+
+unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
+			 struct page **res_page)
+{
+	struct super_block *s = dir->i_sb;
+	struct qnx6_inode_info *ei = QNX6_I(dir);
+	struct page *page = NULL;
+	unsigned long start, n;
+	unsigned long npages = dir_pages(dir);
+	unsigned ino;
+	struct qnx6_dir_entry *de;
+	struct qnx6_long_dir_entry *lde;
+
+	*res_page = NULL;
+
+	if (npages == 0)
+		return 0;
+	start = ei->i_dir_start_lookup;
+	if (start >= npages)
+		start = 0;
+	n = start;
+
+	do {
+		page = qnx6_get_page(dir, n);
+		if (!IS_ERR(page)) {
+			int limit = last_entry(dir, n);
+			int i;
+
+			de = (struct qnx6_dir_entry *)page_address(page);
+			for (i = 0; i < limit; i++, de++) {
+				if (len <= QNX6_SHORT_NAME_MAX) {
+					/* short filename */
+					if (len != de->de_size)
+						continue;
+					ino = qnx6_match(s, len, name, de);
+					if (ino)
+						goto found;
+				} else if (de->de_size == 0xff) {
+					/* deal with long filename */
+					lde = (struct qnx6_long_dir_entry *)de;
+					ino = qnx6_long_match(len,
+								name, lde, dir);
+					if (ino)
+						goto found;
+				} else
+					printk(KERN_ERR "qnx6: undefined "
+						"filename size in inode.\n");
+			}
+			qnx6_put_page(page);
+		}
+
+		if (++n >= npages)
+			n = 0;
+	} while (n != start);
+	return 0;
+
+found:
+	*res_page = page;
+	ei->i_dir_start_lookup = n;
+	return ino;
+}
+
+const struct file_operations qnx6_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.readdir	= qnx6_readdir,
+	.fsync		= generic_file_fsync,
+};
+
+const struct inode_operations qnx6_dir_inode_operations = {
+	.lookup		= qnx6_lookup,
+};