fs: jffs2: add initial support for reading jffs2

Import the jffs2 filesystem code from Linux v5.5-rc1 and convert it
to work with barebox.

Writing is *not* supported.

Testing was done with a n25q256a-compatible QuadSPI chip on a
SoCFPGA-based Socrates board.

Testing was done with a combination of:
	user@somelinuxhost: mkfs.jffs2 --eraseblock=4 -d fs/jffs2/ -o jffs2.img
	root@target:~ flash_erase -j /dev/mtd5 0 0
	root@target:~ dd if=jffs2.img of=/dev/mtd5
	barebox@EBV SOCrates:/ mount /dev/mtd0.data
	(...)
	mounted /dev/mtd0.data on /mnt/mtd0.data

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

2 files changed, 322 insertions, 0 deletions

diff --git a/include/linux/hash.h b/include/linux/hash.h
new file mode 100644
index 0000000000..ad6fa21d97
--- /dev/null
+++ b/include/linux/hash.h
@@ -0,0 +1,104 @@
+#ifndef _LINUX_HASH_H
+#define _LINUX_HASH_H
+/* Fast hashing routine for ints,  longs and pointers.
+   (C) 2002 Nadia Yvette Chambers, IBM */
+
+#include <asm/types.h>
+#include <linux/compiler.h>
+
+/*
+ * The "GOLDEN_RATIO_PRIME" is used in ifs/btrfs/brtfs_inode.h and
+ * fs/inode.c.  It's not actually prime any more (the previous primes
+ * were actively bad for hashing), but the name remains.
+ */
+#if BITS_PER_LONG == 32
+#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_32
+#define hash_long(val, bits) hash_32(val, bits)
+#elif BITS_PER_LONG == 64
+#define hash_long(val, bits) hash_64(val, bits)
+#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_64
+#else
+#error Wordsize not 32 or 64
+#endif
+
+/*
+ * This hash multiplies the input by a large odd number and takes the
+ * high bits.  Since multiplication propagates changes to the most
+ * significant end only, it is essential that the high bits of the
+ * product be used for the hash value.
+ *
+ * Chuck Lever verified the effectiveness of this technique:
+ * http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
+ *
+ * Although a random odd number will do, it turns out that the golden
+ * ratio phi = (sqrt(5)-1)/2, or its negative, has particularly nice
+ * properties.  (See Knuth vol 3, section 6.4, exercise 9.)
+ *
+ * These are the negative, (1 - phi) = phi**2 = (3 - sqrt(5))/2,
+ * which is very slightly easier to multiply by and makes no
+ * difference to the hash distribution.
+ */
+#define GOLDEN_RATIO_32 0x61C88647
+#define GOLDEN_RATIO_64 0x61C8864680B583EBull
+
+#ifdef CONFIG_HAVE_ARCH_HASH
+/* This header may use the GOLDEN_RATIO_xx constants */
+#include <asm/hash.h>
+#endif
+
+/*
+ * The _generic versions exist only so lib/test_hash.c can compare
+ * the arch-optimized versions with the generic.
+ *
+ * Note that if you change these, any <asm/hash.h> that aren't updated
+ * to match need to have their HAVE_ARCH_* define values updated so the
+ * self-test will not false-positive.
+ */
+#ifndef HAVE_ARCH__HASH_32
+#define __hash_32 __hash_32_generic
+#endif
+static inline u32 __hash_32_generic(u32 val)
+{
+	return val * GOLDEN_RATIO_32;
+}
+
+#ifndef HAVE_ARCH_HASH_32
+#define hash_32 hash_32_generic
+#endif
+static inline u32 hash_32_generic(u32 val, unsigned int bits)
+{
+	/* High bits are more random, so use them. */
+	return __hash_32(val) >> (32 - bits);
+}
+
+#ifndef HAVE_ARCH_HASH_64
+#define hash_64 hash_64_generic
+#endif
+static __always_inline u32 hash_64_generic(u64 val, unsigned int bits)
+{
+#if BITS_PER_LONG == 64
+	/* 64x64-bit multiply is efficient on all 64-bit processors */
+	return val * GOLDEN_RATIO_64 >> (64 - bits);
+#else
+	/* Hash 64 bits using only 32x32-bit multiply. */
+	return hash_32((u32)val ^ __hash_32(val >> 32), bits);
+#endif
+}
+
+static inline u32 hash_ptr(const void *ptr, unsigned int bits)
+{
+	return hash_long((unsigned long)ptr, bits);
+}
+
+/* This really should be called fold32_ptr; it does no hashing to speak of. */
+static inline u32 hash32_ptr(const void *ptr)
+{
+	unsigned long val = (unsigned long)ptr;
+
+#if BITS_PER_LONG == 64
+	val ^= (val >> 32);
+#endif
+	return (u32)val;
+}
+
+#endif /* _LINUX_HASH_H */
diff --git a/include/linux/jffs2.h b/include/linux/jffs2.h
new file mode 100644
index 0000000000..ed2ebcfc42
--- /dev/null
+++ b/include/linux/jffs2.h
@@ -0,0 +1,218 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in the
+ * jffs2 directory.
+ */
+
+#ifndef __LINUX_JFFS2_H__
+#define __LINUX_JFFS2_H__
+
+#include <linux/types.h>
+#include <linux/magic.h>
+
+/* You must include something which defines the C99 uintXX_t types.
+   We don't do it from here because this file is used in too many
+   different environments. */
+
+/* Values we may expect to find in the 'magic' field */
+#define JFFS2_OLD_MAGIC_BITMASK 0x1984
+#define JFFS2_MAGIC_BITMASK 0x1985
+#define KSAMTIB_CIGAM_2SFFJ 0x8519 /* For detecting wrong-endian fs */
+#define JFFS2_EMPTY_BITMASK 0xffff
+#define JFFS2_DIRTY_BITMASK 0x0000
+
+/* Summary node MAGIC marker */
+#define JFFS2_SUM_MAGIC	0x02851885
+
+/* We only allow a single char for length, and 0xFF is empty flash so
+   we don't want it confused with a real length. Hence max 254.
+*/
+#define JFFS2_MAX_NAME_LEN 254
+
+/* How small can we sensibly write nodes? */
+#define JFFS2_MIN_DATA_LEN 128
+
+#define JFFS2_COMPR_NONE	0x00
+#define JFFS2_COMPR_ZERO	0x01
+#define JFFS2_COMPR_RTIME	0x02
+#define JFFS2_COMPR_RUBINMIPS	0x03
+#define JFFS2_COMPR_COPY	0x04
+#define JFFS2_COMPR_DYNRUBIN	0x05
+#define JFFS2_COMPR_ZLIB	0x06
+#define JFFS2_COMPR_LZO		0x07
+/* Compatibility flags. */
+#define JFFS2_COMPAT_MASK 0xc000      /* What do to if an unknown nodetype is found */
+#define JFFS2_NODE_ACCURATE 0x2000
+/* INCOMPAT: Fail to mount the filesystem */
+#define JFFS2_FEATURE_INCOMPAT 0xc000
+/* ROCOMPAT: Mount read-only */
+#define JFFS2_FEATURE_ROCOMPAT 0x8000
+/* RWCOMPAT_COPY: Mount read/write, and copy the node when it's GC'd */
+#define JFFS2_FEATURE_RWCOMPAT_COPY 0x4000
+/* RWCOMPAT_DELETE: Mount read/write, and delete the node when it's GC'd */
+#define JFFS2_FEATURE_RWCOMPAT_DELETE 0x0000
+
+#define JFFS2_NODETYPE_DIRENT (JFFS2_FEATURE_INCOMPAT | JFFS2_NODE_ACCURATE | 1)
+#define JFFS2_NODETYPE_INODE (JFFS2_FEATURE_INCOMPAT | JFFS2_NODE_ACCURATE | 2)
+#define JFFS2_NODETYPE_CLEANMARKER (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 3)
+#define JFFS2_NODETYPE_PADDING (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 4)
+
+#define JFFS2_NODETYPE_SUMMARY (JFFS2_FEATURE_RWCOMPAT_DELETE | JFFS2_NODE_ACCURATE | 6)
+
+#define JFFS2_NODETYPE_XATTR (JFFS2_FEATURE_INCOMPAT | JFFS2_NODE_ACCURATE | 8)
+#define JFFS2_NODETYPE_XREF (JFFS2_FEATURE_INCOMPAT | JFFS2_NODE_ACCURATE | 9)
+
+/* XATTR Related */
+#define JFFS2_XPREFIX_USER		1	/* for "user." */
+#define JFFS2_XPREFIX_SECURITY		2	/* for "security." */
+#define JFFS2_XPREFIX_ACL_ACCESS	3	/* for "system.posix_acl_access" */
+#define JFFS2_XPREFIX_ACL_DEFAULT	4	/* for "system.posix_acl_default" */
+#define JFFS2_XPREFIX_TRUSTED		5	/* for "trusted.*" */
+
+#define JFFS2_ACL_VERSION		0x0001
+
+#define JFFS2_INO_FLAG_PREREAD	  1	/* Do read_inode() for this one at
+					   mount time, don't wait for it to
+					   happen later */
+#define JFFS2_INO_FLAG_USERCOMPR  2	/* User has requested a specific
+					   compression type */
+
+
+/* These can go once we've made sure we've caught all uses without
+   byteswapping */
+
+typedef struct {
+	__u32 v32;
+} __attribute__((packed)) jint32_t;
+
+typedef struct {
+	__u32 m;
+} __attribute__((packed)) jmode_t;
+
+typedef struct {
+	__u16 v16;
+} __attribute__((packed)) jint16_t;
+
+struct jffs2_unknown_node
+{
+	/* All start like this */
+	jint16_t magic;
+	jint16_t nodetype;
+	jint32_t totlen; /* So we can skip over nodes we don't grok */
+	jint32_t hdr_crc;
+};
+
+struct jffs2_raw_dirent
+{
+	jint16_t magic;
+	jint16_t nodetype;	/* == JFFS2_NODETYPE_DIRENT */
+	jint32_t totlen;
+	jint32_t hdr_crc;
+	jint32_t pino;
+	jint32_t version;
+	jint32_t ino; /* == zero for unlink */
+	jint32_t mctime;
+	__u8 nsize;
+	__u8 type;
+	__u8 unused[2];
+	jint32_t node_crc;
+	jint32_t name_crc;
+	__u8 name[0];
+};
+
+/* The JFFS2 raw inode structure: Used for storage on physical media.  */
+/* The uid, gid, atime, mtime and ctime members could be longer, but
+   are left like this for space efficiency. If and when people decide
+   they really need them extended, it's simple enough to add support for
+   a new type of raw node.
+*/
+struct jffs2_raw_inode
+{
+	jint16_t magic;      /* A constant magic number.  */
+	jint16_t nodetype;   /* == JFFS2_NODETYPE_INODE */
+	jint32_t totlen;     /* Total length of this node (inc data, etc.) */
+	jint32_t hdr_crc;
+	jint32_t ino;        /* Inode number.  */
+	jint32_t version;    /* Version number.  */
+	jmode_t mode;       /* The file's type or mode.  */
+	jint16_t uid;        /* The file's owner.  */
+	jint16_t gid;        /* The file's group.  */
+	jint32_t isize;      /* Total resultant size of this inode (used for truncations)  */
+	jint32_t atime;      /* Last access time.  */
+	jint32_t mtime;      /* Last modification time.  */
+	jint32_t ctime;      /* Change time.  */
+	jint32_t offset;     /* Where to begin to write.  */
+	jint32_t csize;      /* (Compressed) data size */
+	jint32_t dsize;	     /* Size of the node's data. (after decompression) */
+	__u8 compr;       /* Compression algorithm used */
+	__u8 usercompr;   /* Compression algorithm requested by the user */
+	jint16_t flags;	     /* See JFFS2_INO_FLAG_* */
+	jint32_t data_crc;   /* CRC for the (compressed) data.  */
+	jint32_t node_crc;   /* CRC for the raw inode (excluding data)  */
+	__u8 data[0];
+};
+
+struct jffs2_raw_xattr {
+	jint16_t magic;
+	jint16_t nodetype;	/* = JFFS2_NODETYPE_XATTR */
+	jint32_t totlen;
+	jint32_t hdr_crc;
+	jint32_t xid;		/* XATTR identifier number */
+	jint32_t version;
+	__u8 xprefix;
+	__u8 name_len;
+	jint16_t value_len;
+	jint32_t data_crc;
+	jint32_t node_crc;
+	__u8 data[0];
+} __attribute__((packed));
+
+struct jffs2_raw_xref
+{
+	jint16_t magic;
+	jint16_t nodetype;	/* = JFFS2_NODETYPE_XREF */
+	jint32_t totlen;
+	jint32_t hdr_crc;
+	jint32_t ino;		/* inode number */
+	jint32_t xid;		/* XATTR identifier number */
+	jint32_t xseqno;	/* xref sequential number */
+	jint32_t node_crc;
+} __attribute__((packed));
+
+struct jffs2_raw_summary
+{
+	jint16_t magic;
+	jint16_t nodetype; 	/* = JFFS2_NODETYPE_SUMMARY */
+	jint32_t totlen;
+	jint32_t hdr_crc;
+	jint32_t sum_num;	/* number of sum entries*/
+	jint32_t cln_mkr;	/* clean marker size, 0 = no cleanmarker */
+	jint32_t padded;	/* sum of the size of padding nodes */
+	jint32_t sum_crc;	/* summary information crc */
+	jint32_t node_crc; 	/* node crc */
+	jint32_t sum[0]; 	/* inode summary info */
+};
+
+union jffs2_node_union
+{
+	struct jffs2_raw_inode i;
+	struct jffs2_raw_dirent d;
+	struct jffs2_raw_xattr x;
+	struct jffs2_raw_xref r;
+	struct jffs2_raw_summary s;
+	struct jffs2_unknown_node u;
+};
+
+/* Data payload for device nodes. */
+union jffs2_device_node {
+	jint16_t old_id;
+	jint32_t new_id;
+};
+
+#endif /* __LINUX_JFFS2_H__ */