xattr.c

linux 内核源代码

			return ERR_PTR(-ENOMEM);
		xd->xid = xid;
		xd->version = version;
		if (xd->xid > c->highest_xid)
			c->highest_xid = xd->xid;
		list_add_tail(&xd->xindex, &c->xattrindex[xid % XATTRINDEX_HASHSIZE]);
	}
	return xd;
}

/* -------- xattr subsystem functions ---------------
 * xprefix_to_handler(xprefix)
 *   is used to translate xprefix into xattr_handler.
 * jffs2_listxattr(dentry, buffer, size)
 *   is an implementation of listxattr handler on jffs2.
 * do_jffs2_getxattr(inode, xprefix, xname, buffer, size)
 *   is an implementation of getxattr handler on jffs2.
 * do_jffs2_setxattr(inode, xprefix, xname, buffer, size, flags)
 *   is an implementation of setxattr handler on jffs2.
 * -------------------------------------------------- */
struct xattr_handler *jffs2_xattr_handlers[] = {
	&jffs2_user_xattr_handler,
#ifdef CONFIG_JFFS2_FS_SECURITY
	&jffs2_security_xattr_handler,
#endif
#ifdef CONFIG_JFFS2_FS_POSIX_ACL
	&jffs2_acl_access_xattr_handler,
	&jffs2_acl_default_xattr_handler,
#endif
	&jffs2_trusted_xattr_handler,
	NULL
};

static struct xattr_handler *xprefix_to_handler(int xprefix) {
	struct xattr_handler *ret;

	switch (xprefix) {
	case JFFS2_XPREFIX_USER:
		ret = &jffs2_user_xattr_handler;
		break;
#ifdef CONFIG_JFFS2_FS_SECURITY
	case JFFS2_XPREFIX_SECURITY:
		ret = &jffs2_security_xattr_handler;
		break;
#endif
#ifdef CONFIG_JFFS2_FS_POSIX_ACL
	case JFFS2_XPREFIX_ACL_ACCESS:
		ret = &jffs2_acl_access_xattr_handler;
		break;
	case JFFS2_XPREFIX_ACL_DEFAULT:
		ret = &jffs2_acl_default_xattr_handler;
		break;
#endif
	case JFFS2_XPREFIX_TRUSTED:
		ret = &jffs2_trusted_xattr_handler;
		break;
	default:
		ret = NULL;
		break;
	}
	return ret;
}

ssize_t jffs2_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
	struct inode *inode = dentry->d_inode;
	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
	struct jffs2_inode_cache *ic = f->inocache;
	struct jffs2_xattr_ref *ref, **pref;
	struct jffs2_xattr_datum *xd;
	struct xattr_handler *xhandle;
	ssize_t len, rc;
	int retry = 0;

	rc = check_xattr_ref_inode(c, ic);
	if (unlikely(rc))
		return rc;

	down_read(&c->xattr_sem);
 retry:
	len = 0;
	for (ref=ic->xref, pref=&ic->xref; ref; pref=&ref->next, ref=ref->next) {
		BUG_ON(ref->ic != ic);
		xd = ref->xd;
		if (!xd->xname) {
			/* xdatum is unchached */
			if (!retry) {
				retry = 1;
				up_read(&c->xattr_sem);
				down_write(&c->xattr_sem);
				goto retry;
			} else {
				rc = load_xattr_datum(c, xd);
				if (unlikely(rc > 0)) {
					*pref = ref->next;
					delete_xattr_ref(c, ref);
					goto retry;
				} else if (unlikely(rc < 0))
					goto out;
			}
		}
		xhandle = xprefix_to_handler(xd->xprefix);
		if (!xhandle)
			continue;
		if (buffer) {
			rc = xhandle->list(inode, buffer+len, size-len, xd->xname, xd->name_len);
		} else {
			rc = xhandle->list(inode, NULL, 0, xd->xname, xd->name_len);
		}
		if (rc < 0)
			goto out;
		len += rc;
	}
	rc = len;
 out:
	if (!retry) {
		up_read(&c->xattr_sem);
	} else {
		up_write(&c->xattr_sem);
	}
	return rc;
}

int do_jffs2_getxattr(struct inode *inode, int xprefix, const char *xname,
		      char *buffer, size_t size)
{
	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
	struct jffs2_inode_cache *ic = f->inocache;
	struct jffs2_xattr_datum *xd;
	struct jffs2_xattr_ref *ref, **pref;
	int rc, retry = 0;

	rc = check_xattr_ref_inode(c, ic);
	if (unlikely(rc))
		return rc;

	down_read(&c->xattr_sem);
 retry:
	for (ref=ic->xref, pref=&ic->xref; ref; pref=&ref->next, ref=ref->next) {
		BUG_ON(ref->ic!=ic);

		xd = ref->xd;
		if (xd->xprefix != xprefix)
			continue;
		if (!xd->xname) {
			/* xdatum is unchached */
			if (!retry) {
				retry = 1;
				up_read(&c->xattr_sem);
				down_write(&c->xattr_sem);
				goto retry;
			} else {
				rc = load_xattr_datum(c, xd);
				if (unlikely(rc > 0)) {
					*pref = ref->next;
					delete_xattr_ref(c, ref);
					goto retry;
				} else if (unlikely(rc < 0)) {
					goto out;
				}
			}
		}
		if (!strcmp(xname, xd->xname)) {
			rc = xd->value_len;
			if (buffer) {
				if (size < rc) {
					rc = -ERANGE;
				} else {
					memcpy(buffer, xd->xvalue, rc);
				}
			}
			goto out;
		}
	}
	rc = -ENODATA;
 out:
	if (!retry) {
		up_read(&c->xattr_sem);
	} else {
		up_write(&c->xattr_sem);
	}
	return rc;
}

int do_jffs2_setxattr(struct inode *inode, int xprefix, const char *xname,
		      const char *buffer, size_t size, int flags)
{
	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
	struct jffs2_inode_cache *ic = f->inocache;
	struct jffs2_xattr_datum *xd;
	struct jffs2_xattr_ref *ref, *newref, **pref;
	uint32_t length, request;
	int rc;

	rc = check_xattr_ref_inode(c, ic);
	if (unlikely(rc))
		return rc;

	request = PAD(sizeof(struct jffs2_raw_xattr) + strlen(xname) + 1 + size);
	rc = jffs2_reserve_space(c, request, &length,
				 ALLOC_NORMAL, JFFS2_SUMMARY_XATTR_SIZE);
	if (rc) {
		JFFS2_WARNING("jffs2_reserve_space()=%d, request=%u\n", rc, request);
		return rc;
	}

	/* Find existing xattr */
	down_write(&c->xattr_sem);
 retry:
	for (ref=ic->xref, pref=&ic->xref; ref; pref=&ref->next, ref=ref->next) {
		xd = ref->xd;
		if (xd->xprefix != xprefix)
			continue;
		if (!xd->xname) {
			rc = load_xattr_datum(c, xd);
			if (unlikely(rc > 0)) {
				*pref = ref->next;
				delete_xattr_ref(c, ref);
				goto retry;
			} else if (unlikely(rc < 0))
				goto out;
		}
		if (!strcmp(xd->xname, xname)) {
			if (flags & XATTR_CREATE) {
				rc = -EEXIST;
				goto out;
			}
			if (!buffer) {
				ref->ino = ic->ino;
				ref->xid = xd->xid;
				ref->xseqno |= XREF_DELETE_MARKER;
				rc = save_xattr_ref(c, ref);
				if (!rc) {
					*pref = ref->next;
					spin_lock(&c->erase_completion_lock);
					ref->next = c->xref_dead_list;
					c->xref_dead_list = ref;
					spin_unlock(&c->erase_completion_lock);
					unrefer_xattr_datum(c, xd);
				} else {
					ref->ic = ic;
					ref->xd = xd;
					ref->xseqno &= ~XREF_DELETE_MARKER;
				}
				goto out;
			}
			goto found;
		}
	}
	/* not found */
	if (flags & XATTR_REPLACE) {
		rc = -ENODATA;
		goto out;
	}
	if (!buffer) {
		rc = -ENODATA;
		goto out;
	}
 found:
	xd = create_xattr_datum(c, xprefix, xname, buffer, size);
	if (IS_ERR(xd)) {
		rc = PTR_ERR(xd);
		goto out;
	}
	up_write(&c->xattr_sem);
	jffs2_complete_reservation(c);

	/* create xattr_ref */
	request = PAD(sizeof(struct jffs2_raw_xref));
	rc = jffs2_reserve_space(c, request, &length,
				 ALLOC_NORMAL, JFFS2_SUMMARY_XREF_SIZE);
	down_write(&c->xattr_sem);
	if (rc) {
		JFFS2_WARNING("jffs2_reserve_space()=%d, request=%u\n", rc, request);
		unrefer_xattr_datum(c, xd);
		up_write(&c->xattr_sem);
		return rc;
	}
	if (ref)
		*pref = ref->next;
	newref = create_xattr_ref(c, ic, xd);
	if (IS_ERR(newref)) {
		if (ref) {
			ref->next = ic->xref;
			ic->xref = ref;
		}
		rc = PTR_ERR(newref);
		unrefer_xattr_datum(c, xd);
	} else if (ref) {
		delete_xattr_ref(c, ref);
	}
 out:
	up_write(&c->xattr_sem);
	jffs2_complete_reservation(c);
	return rc;
}

/* -------- garbage collector functions -------------
 * jffs2_garbage_collect_xattr_datum(c, xd, raw)
 *   is used to move xdatum into new node.
 * jffs2_garbage_collect_xattr_ref(c, ref, raw)
 *   is used to move xref into new node.
 * jffs2_verify_xattr(c)
 *   is used to call do_verify_xattr_datum() before garbage collecting.
 * jffs2_release_xattr_datum(c, xd)
 *   is used to release an in-memory object of xdatum.
 * jffs2_release_xattr_ref(c, ref)
 *   is used to release an in-memory object of xref.
 * -------------------------------------------------- */
int jffs2_garbage_collect_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd,
				      struct jffs2_raw_node_ref *raw)
{
	uint32_t totlen, length, old_ofs;
	int rc = 0;

	down_write(&c->xattr_sem);
	if (xd->node != raw)
		goto out;
	if (xd->flags & (JFFS2_XFLAGS_DEAD|JFFS2_XFLAGS_INVALID))
		goto out;

	rc = load_xattr_datum(c, xd);
	if (unlikely(rc)) {
		rc = (rc > 0) ? 0 : rc;
		goto out;
	}
	old_ofs = ref_offset(xd->node);
	totlen = PAD(sizeof(struct jffs2_raw_xattr)
			+ xd->name_len + 1 + xd->value_len);
	rc = jffs2_reserve_space_gc(c, totlen, &length, JFFS2_SUMMARY_XATTR_SIZE);
	if (rc) {
		JFFS2_WARNING("jffs2_reserve_space_gc()=%d, request=%u\n", rc, totlen);
		goto out;
	}
	rc = save_xattr_datum(c, xd);
	if (!rc)
		dbg_xattr("xdatum (xid=%u, version=%u) GC'ed from %#08x to %08x\n",
			  xd->xid, xd->version, old_ofs, ref_offset(xd->node));
 out:
	if (!rc)
		jffs2_mark_node_obsolete(c, raw);
	up_write(&c->xattr_sem);
	return rc;
}

int jffs2_garbage_collect_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref,
				    struct jffs2_raw_node_ref *raw)
{
	uint32_t totlen, length, old_ofs;
	int rc = 0;

	down_write(&c->xattr_sem);
	BUG_ON(!ref->node);

	if (ref->node != raw)
		goto out;
	if (is_xattr_ref_dead(ref) && (raw->next_in_ino == (void *)ref))
		goto out;

	old_ofs = ref_offset(ref->node);
	totlen = ref_totlen(c, c->gcblock, ref->node);

	rc = jffs2_reserve_space_gc(c, totlen, &length, JFFS2_SUMMARY_XREF_SIZE);
	if (rc) {
		JFFS2_WARNING("%s: jffs2_reserve_space_gc() = %d, request = %u\n",
			      __FUNCTION__, rc, totlen);
		rc = rc ? rc : -EBADFD;
		goto out;
	}
	rc = save_xattr_ref(c, ref);
	if (!rc)
		dbg_xattr("xref (ino=%u, xid=%u) GC'ed from %#08x to %08x\n",
			  ref->ic->ino, ref->xd->xid, old_ofs, ref_offset(ref->node));
 out:
	if (!rc)
		jffs2_mark_node_obsolete(c, raw);
	up_write(&c->xattr_sem);
	return rc;
}

int jffs2_verify_xattr(struct jffs2_sb_info *c)
{
	struct jffs2_xattr_datum *xd, *_xd;
	struct jffs2_eraseblock *jeb;
	struct jffs2_raw_node_ref *raw;
	uint32_t totlen;
	int rc;

	down_write(&c->xattr_sem);
	list_for_each_entry_safe(xd, _xd, &c->xattr_unchecked, xindex) {
		rc = do_verify_xattr_datum(c, xd);
		if (rc < 0)
			continue;
		list_del_init(&xd->xindex);
		spin_lock(&c->erase_completion_lock);
		for (raw=xd->node; raw != (void *)xd; raw=raw->next_in_ino) {
			if (ref_flags(raw) != REF_UNCHECKED)
				continue;
			jeb = &c->blocks[ref_offset(raw) / c->sector_size];
			totlen = PAD(ref_totlen(c, jeb, raw));
			c->unchecked_size -= totlen; c->used_size += totlen;
			jeb->unchecked_size -= totlen; jeb->used_size += totlen;
			raw->flash_offset = ref_offset(raw)
				| ((xd->node == (void *)raw) ? REF_PRISTINE : REF_NORMAL);
		}
		if (xd->flags & JFFS2_XFLAGS_DEAD)
			list_add(&xd->xindex, &c->xattr_dead_list);
		spin_unlock(&c->erase_completion_lock);
	}
	up_write(&c->xattr_sem);
	return list_empty(&c->xattr_unchecked) ? 1 : 0;
}

void jffs2_release_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd)
{
	/* must be called under spin_lock(&c->erase_completion_lock) */
	if (atomic_read(&xd->refcnt) || xd->node != (void *)xd)
		return;

	list_del(&xd->xindex);
	jffs2_free_xattr_datum(xd);
}

void jffs2_release_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref)
{
	/* must be called under spin_lock(&c->erase_completion_lock) */
	struct jffs2_xattr_ref *tmp, **ptmp;

	if (ref->node != (void *)ref)
		return;

	for (tmp=c->xref_dead_list, ptmp=&c->xref_dead_list; tmp; ptmp=&tmp->next, tmp=tmp->next) {
		if (ref == tmp) {
			*ptmp = tmp->next;
			break;
		}
	}
	jffs2_free_xattr_ref(ref);
}