xattr.c

linux 内核源代码

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2006  NEC Corporation
 *
 * Created by KaiGai Kohei <[e-mail]>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/crc32.h>
#include <linux/jffs2.h>
#include <linux/xattr.h>
#include <linux/mtd/mtd.h>
#include "nodelist.h"
/* -------- xdatum related functions ----------------
 * xattr_datum_hashkey(xprefix, xname, xvalue, xsize)
 *   is used to calcurate xdatum hashkey. The reminder of hashkey into XATTRINDEX_HASHSIZE is
 *   the index of the xattr name/value pair cache (c->xattrindex).
 * is_xattr_datum_unchecked(c, xd)
 *   returns 1, if xdatum contains any unchecked raw nodes. if all raw nodes are not
 *   unchecked, it returns 0.
 * unload_xattr_datum(c, xd)
 *   is used to release xattr name/value pair and detach from c->xattrindex.
 * reclaim_xattr_datum(c)
 *   is used to reclaim xattr name/value pairs on the xattr name/value pair cache when
 *   memory usage by cache is over c->xdatum_mem_threshold. Currentry, this threshold 
 *   is hard coded as 32KiB.
 * do_verify_xattr_datum(c, xd)
 *   is used to load the xdatum informations without name/value pair from the medium.
 *   It's necessary once, because those informations are not collected during mounting
 *   process when EBS is enabled.
 *   0 will be returned, if success. An negative return value means recoverable error, and
 *   positive return value means unrecoverable error. Thus, caller must remove this xdatum
 *   and xref when it returned positive value.
 * do_load_xattr_datum(c, xd)
 *   is used to load name/value pair from the medium.
 *   The meanings of return value is same as do_verify_xattr_datum().
 * load_xattr_datum(c, xd)
 *   is used to be as a wrapper of do_verify_xattr_datum() and do_load_xattr_datum().
 *   If xd need to call do_verify_xattr_datum() at first, it's called before calling
 *   do_load_xattr_datum(). The meanings of return value is same as do_verify_xattr_datum().
 * save_xattr_datum(c, xd)
 *   is used to write xdatum to medium. xd->version will be incremented.
 * create_xattr_datum(c, xprefix, xname, xvalue, xsize)
 *   is used to create new xdatum and write to medium.
 * unrefer_xattr_datum(c, xd)
 *   is used to delete a xdatum. When nobody refers this xdatum, JFFS2_XFLAGS_DEAD
 *   is set on xd->flags and chained xattr_dead_list or release it immediately.
 *   In the first case, the garbage collector release it later.
 * -------------------------------------------------- */
static uint32_t xattr_datum_hashkey(int xprefix, const char *xname, const char *xvalue, int xsize)
{
	int name_len = strlen(xname);

	return crc32(xprefix, xname, name_len) ^ crc32(xprefix, xvalue, xsize);
}

static int is_xattr_datum_unchecked(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	struct jffs2_raw_node_ref *raw;
	int rc = 0;

	spin_lock(&c->erase_completion_lock);
	for (raw=xd->node; raw != (void *)xd; raw=raw->next_in_ino) {
		if (ref_flags(raw) == REF_UNCHECKED) {
			rc = 1;
			break;
		}
	}
	spin_unlock(&c->erase_completion_lock);
	return rc;
}

static void unload_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	/* must be called under down_write(xattr_sem) */
	D1(dbg_xattr("%s: xid=%u, version=%u\n", __FUNCTION__, xd->xid, xd->version));
	if (xd->xname) {
		c->xdatum_mem_usage -= (xd->name_len + 1 + xd->value_len);
		kfree(xd->xname);
	}

	list_del_init(&xd->xindex);
	xd->hashkey = 0;
	xd->xname = NULL;
	xd->xvalue = NULL;
}

static void reclaim_xattr_datum(struct jffs2_sb_info *c)
{
	/* must be called under down_write(xattr_sem) */
	struct jffs2_xattr_datum *xd, *_xd;
	uint32_t target, before;
	static int index = 0;
	int count;

	if (c->xdatum_mem_threshold > c->xdatum_mem_usage)
		return;

	before = c->xdatum_mem_usage;
	target = c->xdatum_mem_usage * 4 / 5; /* 20% reduction */
	for (count = 0; count < XATTRINDEX_HASHSIZE; count++) {
		list_for_each_entry_safe(xd, _xd, &c->xattrindex[index], xindex) {
			if (xd->flags & JFFS2_XFLAGS_HOT) {
				xd->flags &= ~JFFS2_XFLAGS_HOT;
			} else if (!(xd->flags & JFFS2_XFLAGS_BIND)) {
				unload_xattr_datum(c, xd);
			}
			if (c->xdatum_mem_usage <= target)
				goto out;
		}
		index = (index+1) % XATTRINDEX_HASHSIZE;
	}
 out:
	JFFS2_NOTICE("xdatum_mem_usage from %u byte to %u byte (%u byte reclaimed)\n",
		     before, c->xdatum_mem_usage, before - c->xdatum_mem_usage);
}

static int do_verify_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	/* must be called under down_write(xattr_sem) */
	struct jffs2_eraseblock *jeb;
	struct jffs2_raw_node_ref *raw;
	struct jffs2_raw_xattr rx;
	size_t readlen;
	uint32_t crc, offset, totlen;
	int rc;

	spin_lock(&c->erase_completion_lock);
	offset = ref_offset(xd->node);
	if (ref_flags(xd->node) == REF_PRISTINE)
		goto complete;
	spin_unlock(&c->erase_completion_lock);

	rc = jffs2_flash_read(c, offset, sizeof(rx), &readlen, (char *)&rx);
	if (rc || readlen != sizeof(rx)) {
		JFFS2_WARNING("jffs2_flash_read()=%d, req=%zu, read=%zu at %#08x\n",
			      rc, sizeof(rx), readlen, offset);
		return rc ? rc : -EIO;
	}
	crc = crc32(0, &rx, sizeof(rx) - 4);
	if (crc != je32_to_cpu(rx.node_crc)) {
		JFFS2_ERROR("node CRC failed at %#08x, read=%#08x, calc=%#08x\n",
			    offset, je32_to_cpu(rx.hdr_crc), crc);
		xd->flags |= JFFS2_XFLAGS_INVALID;
		return EIO;
	}
	totlen = PAD(sizeof(rx) + rx.name_len + 1 + je16_to_cpu(rx.value_len));
	if (je16_to_cpu(rx.magic) != JFFS2_MAGIC_BITMASK
	    || je16_to_cpu(rx.nodetype) != JFFS2_NODETYPE_XATTR
	    || je32_to_cpu(rx.totlen) != totlen
	    || je32_to_cpu(rx.xid) != xd->xid
	    || je32_to_cpu(rx.version) != xd->version) {
		JFFS2_ERROR("inconsistent xdatum at %#08x, magic=%#04x/%#04x, "
			    "nodetype=%#04x/%#04x, totlen=%u/%u, xid=%u/%u, version=%u/%u\n",
			    offset, je16_to_cpu(rx.magic), JFFS2_MAGIC_BITMASK,
			    je16_to_cpu(rx.nodetype), JFFS2_NODETYPE_XATTR,
			    je32_to_cpu(rx.totlen), totlen,
			    je32_to_cpu(rx.xid), xd->xid,
			    je32_to_cpu(rx.version), xd->version);
		xd->flags |= JFFS2_XFLAGS_INVALID;
		return EIO;
	}
	xd->xprefix = rx.xprefix;
	xd->name_len = rx.name_len;
	xd->value_len = je16_to_cpu(rx.value_len);
	xd->data_crc = je32_to_cpu(rx.data_crc);

	spin_lock(&c->erase_completion_lock);
 complete:
	for (raw=xd->node; raw != (void *)xd; raw=raw->next_in_ino) {
		jeb = &c->blocks[ref_offset(raw) / c->sector_size];
		totlen = PAD(ref_totlen(c, jeb, raw));
		if (ref_flags(raw) == REF_UNCHECKED) {
			c->unchecked_size -= totlen; c->used_size += totlen;
			jeb->unchecked_size -= totlen; jeb->used_size += totlen;
		}
		raw->flash_offset = ref_offset(raw) | ((xd->node==raw) ? REF_PRISTINE : REF_NORMAL);
	}
	spin_unlock(&c->erase_completion_lock);

	/* unchecked xdatum is chained with c->xattr_unchecked */
	list_del_init(&xd->xindex);

	dbg_xattr("success on verfying xdatum (xid=%u, version=%u)\n",
		  xd->xid, xd->version);

	return 0;
}

static int do_load_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	/* must be called under down_write(xattr_sem) */
	char *data;
	size_t readlen;
	uint32_t crc, length;
	int i, ret, retry = 0;

	BUG_ON(ref_flags(xd->node) != REF_PRISTINE);
	BUG_ON(!list_empty(&xd->xindex));
 retry:
	length = xd->name_len + 1 + xd->value_len;
	data = kmalloc(length, GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	ret = jffs2_flash_read(c, ref_offset(xd->node)+sizeof(struct jffs2_raw_xattr),
			       length, &readlen, data);

	if (ret || length!=readlen) {
		JFFS2_WARNING("jffs2_flash_read() returned %d, request=%d, readlen=%zu, at %#08x\n",
			      ret, length, readlen, ref_offset(xd->node));
		kfree(data);
		return ret ? ret : -EIO;
	}

	data[xd->name_len] = '\0';
	crc = crc32(0, data, length);
	if (crc != xd->data_crc) {
		JFFS2_WARNING("node CRC failed (JFFS2_NODETYPE_XREF)"
			      " at %#08x, read: 0x%08x calculated: 0x%08x\n",
			      ref_offset(xd->node), xd->data_crc, crc);
		kfree(data);
		xd->flags |= JFFS2_XFLAGS_INVALID;
		return EIO;
	}

	xd->flags |= JFFS2_XFLAGS_HOT;
	xd->xname = data;
	xd->xvalue = data + xd->name_len+1;

	c->xdatum_mem_usage += length;

	xd->hashkey = xattr_datum_hashkey(xd->xprefix, xd->xname, xd->xvalue, xd->value_len);
	i = xd->hashkey % XATTRINDEX_HASHSIZE;
	list_add(&xd->xindex, &c->xattrindex[i]);
	if (!retry) {
		retry = 1;
		reclaim_xattr_datum(c);
		if (!xd->xname)
			goto retry;
	}

	dbg_xattr("success on loading xdatum (xid=%u, xprefix=%u, xname='%s')\n",
		  xd->xid, xd->xprefix, xd->xname);

	return 0;
}

static int load_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	/* must be called under down_write(xattr_sem);
	 * rc < 0 : recoverable error, try again
	 * rc = 0 : success
	 * rc > 0 : Unrecoverable error, this node should be deleted.
	 */
	int rc = 0;

	BUG_ON(xd->flags & JFFS2_XFLAGS_DEAD);
	if (xd->xname)
		return 0;
	if (xd->flags & JFFS2_XFLAGS_INVALID)
		return EIO;
	if (unlikely(is_xattr_datum_unchecked(c, xd)))
		rc = do_verify_xattr_datum(c, xd);
	if (!rc)
		rc = do_load_xattr_datum(c, xd);
	return rc;
}

static int save_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	/* must be called under down_write(xattr_sem) */
	struct jffs2_raw_xattr rx;
	struct kvec vecs[2];
	size_t length;
	int rc, totlen;
	uint32_t phys_ofs = write_ofs(c);

	BUG_ON(!xd->xname);
	BUG_ON(xd->flags & (JFFS2_XFLAGS_DEAD|JFFS2_XFLAGS_INVALID));

	vecs[0].iov_base = &rx;
	vecs[0].iov_len = sizeof(rx);
	vecs[1].iov_base = xd->xname;
	vecs[1].iov_len = xd->name_len + 1 + xd->value_len;
	totlen = vecs[0].iov_len + vecs[1].iov_len;

	/* Setup raw-xattr */
	memset(&rx, 0, sizeof(rx));
	rx.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
	rx.nodetype = cpu_to_je16(JFFS2_NODETYPE_XATTR);
	rx.totlen = cpu_to_je32(PAD(totlen));
	rx.hdr_crc = cpu_to_je32(crc32(0, &rx, sizeof(struct jffs2_unknown_node) - 4));

	rx.xid = cpu_to_je32(xd->xid);
	rx.version = cpu_to_je32(++xd->version);
	rx.xprefix = xd->xprefix;
	rx.name_len = xd->name_len;
	rx.value_len = cpu_to_je16(xd->value_len);
	rx.data_crc = cpu_to_je32(crc32(0, vecs[1].iov_base, vecs[1].iov_len));
	rx.node_crc = cpu_to_je32(crc32(0, &rx, sizeof(struct jffs2_raw_xattr) - 4));

	rc = jffs2_flash_writev(c, vecs, 2, phys_ofs, &length, 0);
	if (rc || totlen != length) {
		JFFS2_WARNING("jffs2_flash_writev()=%d, req=%u, wrote=%zu, at %#08x\n",
			      rc, totlen, length, phys_ofs);
		rc = rc ? rc : -EIO;
		if (length)
			jffs2_add_physical_node_ref(c, phys_ofs | REF_OBSOLETE, PAD(totlen), NULL);

		return rc;
	}
	/* success */
	jffs2_add_physical_node_ref(c, phys_ofs | REF_PRISTINE, PAD(totlen), (void *)xd);

	dbg_xattr("success on saving xdatum (xid=%u, version=%u, xprefix=%u, xname='%s')\n",
		  xd->xid, xd->version, xd->xprefix, xd->xname);

	return 0;
}

static struct jffs2_xattr_datum *create_xattr_datum(struct jffs2_sb_info *c,
						    int xprefix, const char *xname,
						    const char *xvalue, int xsize)
{
	/* must be called under down_write(xattr_sem) */
	struct jffs2_xattr_datum *xd;
	uint32_t hashkey, name_len;
	char *data;
	int i, rc;

	/* Search xattr_datum has same xname/xvalue by index */
	hashkey = xattr_datum_hashkey(xprefix, xname, xvalue, xsize);
	i = hashkey % XATTRINDEX_HASHSIZE;
	list_for_each_entry(xd, &c->xattrindex[i], xindex) {
		if (xd->hashkey==hashkey
		    && xd->xprefix==xprefix
		    && xd->value_len==xsize
		    && !strcmp(xd->xname, xname)
		    && !memcmp(xd->xvalue, xvalue, xsize)) {
			atomic_inc(&xd->refcnt);
			return xd;
		}
	}

	/* Not found, Create NEW XATTR-Cache */
	name_len = strlen(xname);

	xd = jffs2_alloc_xattr_datum();
	if (!xd)
		return ERR_PTR(-ENOMEM);

	data = kmalloc(name_len + 1 + xsize, GFP_KERNEL);
	if (!data) {
		jffs2_free_xattr_datum(xd);
		return ERR_PTR(-ENOMEM);
	}
	strcpy(data, xname);
	memcpy(data + name_len + 1, xvalue, xsize);

	atomic_set(&xd->refcnt, 1);
	xd->xid = ++c->highest_xid;
	xd->flags |= JFFS2_XFLAGS_HOT;
	xd->xprefix = xprefix;

	xd->hashkey = hashkey;
	xd->xname = data;
	xd->xvalue = data + name_len + 1;
	xd->name_len = name_len;
	xd->value_len = xsize;
	xd->data_crc = crc32(0, data, xd->name_len + 1 + xd->value_len);

	rc = save_xattr_datum(c, xd);
	if (rc) {
		kfree(xd->xname);
		jffs2_free_xattr_datum(xd);
		return ERR_PTR(rc);
	}

	/* Insert Hash Index */
	i = hashkey % XATTRINDEX_HASHSIZE;
	list_add(&xd->xindex, &c->xattrindex[i]);

	c->xdatum_mem_usage += (xd->name_len + 1 + xd->value_len);
	reclaim_xattr_datum(c);

	return xd;
}

static void unrefer_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	/* must be called under down_write(xattr_sem) */
	if (atomic_dec_and_lock(&xd->refcnt, &c->erase_completion_lock)) {
		unload_xattr_datum(c, xd);
		xd->flags |= JFFS2_XFLAGS_DEAD;
		if (xd->node == (void *)xd) {
			BUG_ON(!(xd->flags & JFFS2_XFLAGS_INVALID));
			jffs2_free_xattr_datum(xd);
		} else {
			list_add(&xd->xindex, &c->xattr_dead_list);
		}
		spin_unlock(&c->erase_completion_lock);

		dbg_xattr("xdatum(xid=%u, version=%u) was removed.\n",
			  xd->xid, xd->version);
	}
}

/* -------- xref related functions ------------------
 * verify_xattr_ref(c, ref)
 *   is used to load xref information from medium. Because summary data does not
 *   contain xid/ino, it's necessary to verify once while mounting process.
 * save_xattr_ref(c, ref)
 *   is used to write xref to medium. If delete marker is marked, it write
 *   a delete marker of xref into medium.
 * create_xattr_ref(c, ic, xd)
 *   is used to create a new xref and write to medium.
 * delete_xattr_ref(c, ref)
 *   is used to delete jffs2_xattr_ref. It marks xref XREF_DELETE_MARKER,
 *   and allows GC to reclaim those physical nodes.
 * jffs2_xattr_delete_inode(c, ic)
 *   is called to remove xrefs related to obsolete inode when inode is unlinked.
 * jffs2_xattr_free_inode(c, ic)
 *   is called to release xattr related objects when unmounting. 
 * check_xattr_ref_inode(c, ic)
 *   is used to confirm inode does not have duplicate xattr name/value pair.
 * -------------------------------------------------- */
static int verify_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref)
{
	struct jffs2_eraseblock *jeb;
	struct jffs2_raw_node_ref *raw;
	struct jffs2_raw_xref rr;
	size_t readlen;
	uint32_t crc, offset, totlen;