nodelist.h

linux 内核源代码

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 *
 * Created by David Woodhouse <[e-mail]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#ifndef __JFFS2_NODELIST_H__
#define __JFFS2_NODELIST_H__

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/jffs2.h>
#include "jffs2_fs_sb.h"
#include "jffs2_fs_i.h"
#include "xattr.h"
#include "acl.h"
#include "summary.h"

#ifdef __ECOS
#include "os-ecos.h"
#else
#include <linux/mtd/compatmac.h> /* For compatibility with older kernels */
#include "os-linux.h"
#endif

#define JFFS2_NATIVE_ENDIAN

/* Note we handle mode bits conversion from JFFS2 (i.e. Linux) to/from
   whatever OS we're actually running on here too. */

#if defined(JFFS2_NATIVE_ENDIAN)
#define cpu_to_je16(x) ((jint16_t){x})
#define cpu_to_je32(x) ((jint32_t){x})
#define cpu_to_jemode(x) ((jmode_t){os_to_jffs2_mode(x)})

#define constant_cpu_to_je16(x) ((jint16_t){x})
#define constant_cpu_to_je32(x) ((jint32_t){x})

#define je16_to_cpu(x) ((x).v16)
#define je32_to_cpu(x) ((x).v32)
#define jemode_to_cpu(x) (jffs2_to_os_mode((x).m))
#elif defined(JFFS2_BIG_ENDIAN)
#define cpu_to_je16(x) ((jint16_t){cpu_to_be16(x)})
#define cpu_to_je32(x) ((jint32_t){cpu_to_be32(x)})
#define cpu_to_jemode(x) ((jmode_t){cpu_to_be32(os_to_jffs2_mode(x))})

#define constant_cpu_to_je16(x) ((jint16_t){__constant_cpu_to_be16(x)})
#define constant_cpu_to_je32(x) ((jint32_t){__constant_cpu_to_be32(x)})

#define je16_to_cpu(x) (be16_to_cpu(x.v16))
#define je32_to_cpu(x) (be32_to_cpu(x.v32))
#define jemode_to_cpu(x) (be32_to_cpu(jffs2_to_os_mode((x).m)))
#elif defined(JFFS2_LITTLE_ENDIAN)
#define cpu_to_je16(x) ((jint16_t){cpu_to_le16(x)})
#define cpu_to_je32(x) ((jint32_t){cpu_to_le32(x)})
#define cpu_to_jemode(x) ((jmode_t){cpu_to_le32(os_to_jffs2_mode(x))})

#define constant_cpu_to_je16(x) ((jint16_t){__constant_cpu_to_le16(x)})
#define constant_cpu_to_je32(x) ((jint32_t){__constant_cpu_to_le32(x)})

#define je16_to_cpu(x) (le16_to_cpu(x.v16))
#define je32_to_cpu(x) (le32_to_cpu(x.v32))
#define jemode_to_cpu(x) (le32_to_cpu(jffs2_to_os_mode((x).m)))
#else
#error wibble
#endif

/* The minimal node header size */
#define JFFS2_MIN_NODE_HEADER sizeof(struct jffs2_raw_dirent)

/*
  This is all we need to keep in-core for each raw node during normal
  operation. As and when we do read_inode on a particular inode, we can
  scan the nodes which are listed for it and build up a proper map of
  which nodes are currently valid. JFFSv1 always used to keep that whole
  map in core for each inode.
*/
struct jffs2_raw_node_ref
{
	struct jffs2_raw_node_ref *next_in_ino; /* Points to the next raw_node_ref
		for this object. If this _is_ the last, it points to the inode_cache,
		xattr_ref or xattr_datum instead. The common part of those structures
		has NULL in the first word. See jffs2_raw_ref_to_ic() below */
	uint32_t flash_offset;
#define TEST_TOTLEN
#ifdef TEST_TOTLEN
	uint32_t __totlen; /* This may die; use ref_totlen(c, jeb, ) below */
#endif
};

#define REF_LINK_NODE ((int32_t)-1)
#define REF_EMPTY_NODE ((int32_t)-2)

/* Use blocks of about 256 bytes */
#define REFS_PER_BLOCK ((255/sizeof(struct jffs2_raw_node_ref))-1)

static inline struct jffs2_raw_node_ref *ref_next(struct jffs2_raw_node_ref *ref)
{
	ref++;

	/* Link to another block of refs */
	if (ref->flash_offset == REF_LINK_NODE) {
		ref = ref->next_in_ino;
		if (!ref)
			return ref;
	}

	/* End of chain */
	if (ref->flash_offset == REF_EMPTY_NODE)
		return NULL;

	return ref;
}

static inline struct jffs2_inode_cache *jffs2_raw_ref_to_ic(struct jffs2_raw_node_ref *raw)
{
	while(raw->next_in_ino)
		raw = raw->next_in_ino;

	/* NB. This can be a jffs2_xattr_datum or jffs2_xattr_ref and
	   not actually a jffs2_inode_cache. Check ->class */
	return ((struct jffs2_inode_cache *)raw);
}

	/* flash_offset & 3 always has to be zero, because nodes are
	   always aligned at 4 bytes. So we have a couple of extra bits
	   to play with, which indicate the node's status; see below: */
#define REF_UNCHECKED	0	/* We haven't yet checked the CRC or built its inode */
#define REF_OBSOLETE	1	/* Obsolete, can be completely ignored */
#define REF_PRISTINE	2	/* Completely clean. GC without looking */
#define REF_NORMAL	3	/* Possibly overlapped. Read the page and write again on GC */
#define ref_flags(ref)		((ref)->flash_offset & 3)
#define ref_offset(ref)		((ref)->flash_offset & ~3)
#define ref_obsolete(ref)	(((ref)->flash_offset & 3) == REF_OBSOLETE)
#define mark_ref_normal(ref)    do { (ref)->flash_offset = ref_offset(ref) | REF_NORMAL; } while(0)

/* Dirent nodes should be REF_PRISTINE only if they are not a deletion
   dirent. Deletion dirents should be REF_NORMAL so that GC gets to
   throw them away when appropriate */
#define dirent_node_state(rd)	( (je32_to_cpu((rd)->ino)?REF_PRISTINE:REF_NORMAL) )

/* NB: REF_PRISTINE for an inode-less node (ref->next_in_ino == NULL) indicates
   it is an unknown node of type JFFS2_NODETYPE_RWCOMPAT_COPY, so it'll get
   copied. If you need to do anything different to GC inode-less nodes, then
   you need to modify gc.c accordingly. */

/* For each inode in the filesystem, we need to keep a record of
   nlink, because it would be a PITA to scan the whole directory tree
   at read_inode() time to calculate it, and to keep sufficient information
   in the raw_node_ref (basically both parent and child inode number for
   dirent nodes) would take more space than this does. We also keep
   a pointer to the first physical node which is part of this inode, too.
*/
struct jffs2_inode_cache {
	/* First part of structure is shared with other objects which
	   can terminate the raw node refs' next_in_ino list -- which
	   currently struct jffs2_xattr_datum and struct jffs2_xattr_ref. */

	struct jffs2_full_dirent *scan_dents; /* Used during scan to hold
		temporary lists of dirents, and later must be set to
		NULL to mark the end of the raw_node_ref->next_in_ino
		chain. */
	struct jffs2_raw_node_ref *nodes;
	uint8_t class;	/* It's used for identification */

	/* end of shared structure */

	uint8_t flags;
	uint16_t state;
	uint32_t ino;
	struct jffs2_inode_cache *next;
#ifdef CONFIG_JFFS2_FS_XATTR
	struct jffs2_xattr_ref *xref;
#endif
	int nlink;
};

/* Inode states for 'state' above. We need the 'GC' state to prevent
   someone from doing a read_inode() while we're moving a 'REF_PRISTINE'
   node without going through all the iget() nonsense */
#define INO_STATE_UNCHECKED	0	/* CRC checks not yet done */
#define INO_STATE_CHECKING	1	/* CRC checks in progress */
#define INO_STATE_PRESENT	2	/* In core */
#define INO_STATE_CHECKEDABSENT	3	/* Checked, cleared again */
#define INO_STATE_GC		4	/* GCing a 'pristine' node */
#define INO_STATE_READING	5	/* In read_inode() */
#define INO_STATE_CLEARING	6	/* In clear_inode() */

#define INO_FLAGS_XATTR_CHECKED	0x01	/* has no duplicate xattr_ref */

#define RAWNODE_CLASS_INODE_CACHE	0
#define RAWNODE_CLASS_XATTR_DATUM	1
#define RAWNODE_CLASS_XATTR_REF		2

#define INOCACHE_HASHSIZE 128

#define write_ofs(c) ((c)->nextblock->offset + (c)->sector_size - (c)->nextblock->free_size)

/*
  Larger representation of a raw node, kept in-core only when the
  struct inode for this particular ino is instantiated.
*/

struct jffs2_full_dnode
{
	struct jffs2_raw_node_ref *raw;
	uint32_t ofs; /* The offset to which the data of this node belongs */
	uint32_t size;
	uint32_t frags; /* Number of fragments which currently refer
			to this node. When this reaches zero,
			the node is obsolete.  */
};

/*
   Even larger representation of a raw node, kept in-core only while
   we're actually building up the original map of which nodes go where,
   in read_inode()
*/
struct jffs2_tmp_dnode_info
{
	struct rb_node rb;
	struct jffs2_full_dnode *fn;
	uint32_t version;
	uint32_t data_crc;
	uint32_t partial_crc;
	uint16_t csize;
	uint16_t overlapped;
};

/* Temporary data structure used during readinode. */
struct jffs2_readinode_info
{
	struct rb_root tn_root;
	struct jffs2_tmp_dnode_info *mdata_tn;
	uint32_t highest_version;
	uint32_t latest_mctime;