C++ page_address函数代码示例

void __kernel_map_pages(struct page *page, int numpages, int enable)
{
	set_memory_valid((unsigned long)page_address(page), numpages, enable);
}

/*
 * Set up the grant operations for this fragment. If it's a flipping
 * interface, we also set up the unmap request from here.
 */
static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
				struct netrx_pending_operations *npo,
				struct page *page, unsigned long size,
				unsigned long offset, int *head)
{
	struct gnttab_copy *copy_gop;
	struct netbk_rx_meta *meta;
	/*
	 * These variables are used iff get_page_ext returns true,
	 * in which case they are guaranteed to be initialized.
	 */
	unsigned int uninitialized_var(group), uninitialized_var(idx);
	int foreign = get_page_ext(page, &group, &idx);
	unsigned long bytes;

	/* Data must not cross a page boundary. */
	BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));

	meta = npo->meta + npo->meta_prod - 1;

	/* Skip unused frames from start of page */
	page += offset >> PAGE_SHIFT;
	offset &= ~PAGE_MASK;

	while (size > 0) {
		BUG_ON(offset >= PAGE_SIZE);
		BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);

		bytes = PAGE_SIZE - offset;

		if (bytes > size)
			bytes = size;

		if (start_new_rx_buffer(npo->copy_off, bytes, *head)) {
			/*
			 * Netfront requires there to be some data in the head
			 * buffer.
			 */
			BUG_ON(*head);

			meta = get_next_rx_buffer(vif, npo);
		}

		if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
			bytes = MAX_BUFFER_OFFSET - npo->copy_off;

		copy_gop = npo->copy + npo->copy_prod++;
		copy_gop->flags = GNTCOPY_dest_gref;
		if (foreign) {
			struct xen_netbk *netbk = &xen_netbk[group];
			struct pending_tx_info *src_pend;

			src_pend = &netbk->pending_tx_info[idx];

			copy_gop->source.domid = src_pend->vif->domid;
			copy_gop->source.u.ref = src_pend->req.gref;
			copy_gop->flags |= GNTCOPY_source_gref;
		} else {
			void *vaddr = page_address(page);
			copy_gop->source.domid = DOMID_SELF;
			copy_gop->source.u.gmfn = virt_to_mfn(vaddr);
		}
		copy_gop->source.offset = offset;
		copy_gop->dest.domid = vif->domid;

		copy_gop->dest.offset = npo->copy_off;
		copy_gop->dest.u.ref = npo->copy_gref;
		copy_gop->len = bytes;

		npo->copy_off += bytes;
		meta->size += bytes;

		offset += bytes;
		size -= bytes;

		/* Next frame */
		if (offset == PAGE_SIZE && size) {
			BUG_ON(!PageCompound(page));
			page++;
			offset = 0;
		}

		/* Leave a gap for the GSO descriptor. */
		if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
			vif->rx.req_cons++;

		*head = 0; /* There must be something in this buffer now. */

	}
}

//.........这里部分代码省略.........
			/*
			 *	Find where to start putting bytes
			 */
			data = skb_put(skb, fraglen);
			skb_set_network_header(skb, exthdrlen);
			data += fragheaderlen;
			skb->transport_header = (skb->network_header +
						 fragheaderlen);
			if (fraggap) {
				skb->csum = skb_copy_and_csum_bits(
					skb_prev, maxfraglen,
					data + transhdrlen, fraggap, 0);
				skb_prev->csum = csum_sub(skb_prev->csum,
							  skb->csum);
				data += fraggap;
				pskb_trim_unique(skb_prev, maxfraglen);
			}
			copy = datalen - transhdrlen - fraggap;

			if (copy < 0) {
				err = -EINVAL;
				kfree_skb(skb);
				goto error;
			} else if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
				err = -EFAULT;
				kfree_skb(skb);
				goto error;
			}

			offset += copy;
			length -= datalen - fraggap;
			transhdrlen = 0;
			exthdrlen = 0;
			dst_exthdrlen = 0;

			/*
			 * Put the packet on the pending queue
			 */
			__skb_queue_tail(&sk->sk_write_queue, skb);
			continue;
		}

		if (copy > length)
			copy = length;

		if (!(rt->dst.dev->features&NETIF_F_SG)) {
			unsigned int off;

			off = skb->len;
			if (getfrag(from, skb_put(skb, copy),
						offset, copy, off, skb) < 0) {
				__skb_trim(skb, off);
				err = -EFAULT;
				goto error;
			}
		} else {
			int i = skb_shinfo(skb)->nr_frags;
			struct page_frag *pfrag = sk_page_frag(sk);

			err = -ENOMEM;
			if (!sk_page_frag_refill(sk, pfrag))
				goto error;

			if (!skb_can_coalesce(skb, i, pfrag->page,
					      pfrag->offset)) {
				err = -EMSGSIZE;
				if (i == MAX_SKB_FRAGS)
					goto error;

				__skb_fill_page_desc(skb, i, pfrag->page,
						     pfrag->offset, 0);
				skb_shinfo(skb)->nr_frags = ++i;
				get_page(pfrag->page);
			}
			copy = min_t(int, copy, pfrag->size - pfrag->offset);
			if (getfrag(from,
				    page_address(pfrag->page) + pfrag->offset,
				    offset, copy, skb->len, skb) < 0)
				goto error_efault;

			pfrag->offset += copy;
			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
			skb->len += copy;
			skb->data_len += copy;
			skb->truesize += copy;
			atomic_add(copy, &sk->sk_wmem_alloc);
		}
		offset += copy;
		length -= copy;
	}

	return 0;

error_efault:
	err = -EFAULT;
error:
	cork->length -= length;
	IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
	return err;
}

/*
 * This is called when a page-cache page is about to be mapped into a
 * user process' address space.  It offers an opportunity for a
 * port to ensure d-cache/i-cache coherency if necessary.
 *
 * Not entirely sure why this is necessary on SH3 with 32K cache but
 * without it we get occasional "Memory fault" when loading a program.
 */
void flush_icache_page(struct vm_area_struct *vma, struct page *page)
{
	__flush_purge_region(page_address(page), PAGE_SIZE);
}

int jffs2_commit_write (struct file *filp, struct page *pg, unsigned start, unsigned end)
{
	/* Actually commit the write from the page cache page we're looking at.
	 * For now, we write the full page out each time. It sucks, but it's simple
	 */
	struct inode *inode = pg->mapping->host;
	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
	struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
	struct jffs2_raw_inode *ri;
	int ret = 0;
	uint32_t writtenlen = 0;

	D1(printk(KERN_DEBUG "jffs2_commit_write(): ino #%lu, page at 0x%lx, range %d-%d, flags %lx\n",
		  inode->i_ino, pg->index << PAGE_CACHE_SHIFT, start, end, pg->flags));

	if (!start && end == PAGE_CACHE_SIZE) {
		/* We need to avoid deadlock with page_cache_read() in
		   jffs2_garbage_collect_pass(). So we have to mark the
		   page up to date, to prevent page_cache_read() from 
		   trying to re-lock it. */
		SetPageUptodate(pg);
	}

	ri = jffs2_alloc_raw_inode();

	if (!ri) {
		D1(printk(KERN_DEBUG "jffs2_commit_write(): Allocation of raw inode failed\n"));
		return -ENOMEM;
	}

	/* Set the fields that the generic jffs2_write_inode_range() code can't find */
	ri->ino = cpu_to_je32(inode->i_ino);
	ri->mode = cpu_to_jemode(inode->i_mode);
	ri->uid = cpu_to_je16(inode->i_uid);
	ri->gid = cpu_to_je16(inode->i_gid);
	ri->isize = cpu_to_je32((uint32_t)inode->i_size);
	ri->atime = ri->ctime = ri->mtime = cpu_to_je32(get_seconds());

	/* In 2.4, it was already kmapped by generic_file_write(). Doesn't
	   hurt to do it again. The alternative is ifdefs, which are ugly. */
	kmap(pg);

	ret = jffs2_write_inode_range(c, f, ri, page_address(pg) + start,
				      (pg->index << PAGE_CACHE_SHIFT) + start,
				      end - start, &writtenlen);

	kunmap(pg);

	if (ret) {
		/* There was an error writing. */
		SetPageError(pg);
	}

	if (writtenlen) {
		if (inode->i_size < (pg->index << PAGE_CACHE_SHIFT) + start + writtenlen) {
			inode->i_size = (pg->index << PAGE_CACHE_SHIFT) + start + writtenlen;
			inode->i_blocks = (inode->i_size + 511) >> 9;
			
			inode->i_ctime = inode->i_mtime = ITIME(je32_to_cpu(ri->ctime));
		}
	}

static int au_do_copy_file(struct file *dst, struct file *src, loff_t len,
			   char *buf, unsigned long blksize)
{
	int err;
	size_t sz, rbytes, wbytes;
	unsigned char all_zero;
	char *p, *zp;
	struct mutex *h_mtx;
	/* reduce stack usage */
	struct iattr *ia;

	zp = page_address(ZERO_PAGE(0));
	if (unlikely(!zp))
		return -ENOMEM; /* possible? */

	err = 0;
	all_zero = 0;
	while (len) {
		AuDbg("len %lld\n", len);
		sz = blksize;
		if (len < blksize)
			sz = len;

		rbytes = 0;
		/* todo: signal_pending? */
		while (!rbytes || err == -EAGAIN || err == -EINTR) {
			rbytes = vfsub_read_k(src, buf, sz, &src->f_pos);
			err = rbytes;
		}
		if (unlikely(err < 0))
			break;

		all_zero = 0;
		if (len >= rbytes && rbytes == blksize)
			all_zero = !memcmp(buf, zp, rbytes);
		if (!all_zero) {
			wbytes = rbytes;
			p = buf;
			while (wbytes) {
				size_t b;

				b = vfsub_write_k(dst, p, wbytes, &dst->f_pos);
				err = b;
				/* todo: signal_pending? */
				if (unlikely(err == -EAGAIN || err == -EINTR))
					continue;
				if (unlikely(err < 0))
					break;
				wbytes -= b;
				p += b;
			}
		} else {
			loff_t res;

			AuLabel(hole);
			res = vfsub_llseek(dst, rbytes, SEEK_CUR);
			err = res;
			if (unlikely(res < 0))
				break;
		}
		len -= rbytes;
		err = 0;
	}

	/* the last block may be a hole */
	if (!err && all_zero) {
		AuLabel(last hole);

		err = 1;
		if (au_test_nfs(dst->f_dentry->d_sb)) {
			/* nfs requires this step to make last hole */
			/* is this only nfs? */
			do {
				/* todo: signal_pending? */
				err = vfsub_write_k(dst, "\0", 1, &dst->f_pos);
			} while (err == -EAGAIN || err == -EINTR);
			if (err == 1)
				dst->f_pos--;
		}

		if (err == 1) {
			ia = (void *)buf;
			ia->ia_size = dst->f_pos;
			ia->ia_valid = ATTR_SIZE | ATTR_FILE;
			ia->ia_file = dst;
			h_mtx = &dst->f_dentry->d_inode->i_mutex;
			mutex_lock_nested(h_mtx, AuLsc_I_CHILD2);
			err = vfsub_notify_change(&dst->f_path, ia);
			mutex_unlock(h_mtx);
		}
	}

	return err;
}

static int intel_setup_irq_remapping(struct intel_iommu *iommu)
{
	struct ir_table *ir_table;
	struct fwnode_handle *fn;
	unsigned long *bitmap;
	struct page *pages;

	if (iommu->ir_table)
		return 0;

	ir_table = kzalloc(sizeof(struct ir_table), GFP_KERNEL);
	if (!ir_table)
		return -ENOMEM;

	pages = alloc_pages_node(iommu->node, GFP_KERNEL | __GFP_ZERO,
				 INTR_REMAP_PAGE_ORDER);
	if (!pages) {
		pr_err("IR%d: failed to allocate pages of order %d\n",
		       iommu->seq_id, INTR_REMAP_PAGE_ORDER);
		goto out_free_table;
	}

	bitmap = bitmap_zalloc(INTR_REMAP_TABLE_ENTRIES, GFP_ATOMIC);
	if (bitmap == NULL) {
		pr_err("IR%d: failed to allocate bitmap\n", iommu->seq_id);
		goto out_free_pages;
	}

	fn = irq_domain_alloc_named_id_fwnode("INTEL-IR", iommu->seq_id);
	if (!fn)
		goto out_free_bitmap;

	iommu->ir_domain =
		irq_domain_create_hierarchy(arch_get_ir_parent_domain(),
					    0, INTR_REMAP_TABLE_ENTRIES,
					    fn, &intel_ir_domain_ops,
					    iommu);
	irq_domain_free_fwnode(fn);
	if (!iommu->ir_domain) {
		pr_err("IR%d: failed to allocate irqdomain\n", iommu->seq_id);
		goto out_free_bitmap;
	}
	iommu->ir_msi_domain =
		arch_create_remap_msi_irq_domain(iommu->ir_domain,
						 "INTEL-IR-MSI",
						 iommu->seq_id);

	ir_table->base = page_address(pages);
	ir_table->bitmap = bitmap;
	iommu->ir_table = ir_table;

	/*
	 * If the queued invalidation is already initialized,
	 * shouldn't disable it.
	 */
	if (!iommu->qi) {
		/*
		 * Clear previous faults.
		 */
		dmar_fault(-1, iommu);
		dmar_disable_qi(iommu);

		if (dmar_enable_qi(iommu)) {
			pr_err("Failed to enable queued invalidation\n");
			goto out_free_bitmap;
		}
	}

	init_ir_status(iommu);

	if (ir_pre_enabled(iommu)) {
		if (!is_kdump_kernel()) {
			pr_warn("IRQ remapping was enabled on %s but we are not in kdump mode\n",
				iommu->name);
			clear_ir_pre_enabled(iommu);
			iommu_disable_irq_remapping(iommu);
		} else if (iommu_load_old_irte(iommu))
			pr_err("Failed to copy IR table for %s from previous kernel\n",
			       iommu->name);
		else
			pr_info("Copied IR table for %s from previous kernel\n",
				iommu->name);
	}

	iommu_set_irq_remapping(iommu, eim_mode);

	return 0;

out_free_bitmap:
	bitmap_free(bitmap);
out_free_pages:
	__free_pages(pages, INTR_REMAP_PAGE_ORDER);
out_free_table:
	kfree(ir_table);

	iommu->ir_table  = NULL;

	return -ENOMEM;
}

static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req)
{
	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
	struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
	struct ablkcipher_request *subreq;
	crypto_completion_t complete;
	void *data;
	struct scatterlist *osrc, *odst;
	struct scatterlist *dst;
	struct page *srcp;
	struct page *dstp;
	u8 *giv;
	u8 *vsrc;
	u8 *vdst;
	__be64 seq;
	unsigned int ivsize;
	unsigned int len;
	int err;

	subreq = (void *)(reqctx->tail + ctx->reqoff);
	ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));

	giv = req->giv;
	complete = req->creq.base.complete;
	data = req->creq.base.data;

	osrc = req->creq.src;
	odst = req->creq.dst;
	srcp = sg_page(osrc);
	dstp = sg_page(odst);
	vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset;
	vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset;

	ivsize = crypto_ablkcipher_ivsize(geniv);

	if (vsrc != giv + ivsize && vdst != giv + ivsize) {
		giv = PTR_ALIGN((u8 *)reqctx->tail,
				crypto_ablkcipher_alignmask(geniv) + 1);
		complete = eseqiv_complete;
		data = req;
	}

	ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete,
					data);

	sg_init_table(reqctx->src, 2);
	sg_set_buf(reqctx->src, giv, ivsize);
	eseqiv_chain(reqctx->src, osrc, vsrc == giv + ivsize);

	dst = reqctx->src;
	if (osrc != odst) {
		sg_init_table(reqctx->dst, 2);
		sg_set_buf(reqctx->dst, giv, ivsize);
		eseqiv_chain(reqctx->dst, odst, vdst == giv + ivsize);

		dst = reqctx->dst;
	}

	ablkcipher_request_set_crypt(subreq, reqctx->src, dst,
				     req->creq.nbytes + ivsize,
				     req->creq.info);

	memcpy(req->creq.info, ctx->salt, ivsize);

	len = ivsize;
	if (ivsize > sizeof(u64)) {
		memset(req->giv, 0, ivsize - sizeof(u64));
		len = sizeof(u64);
	}
	seq = cpu_to_be64(req->seq);
	memcpy(req->giv + ivsize - len, &seq, len);

	err = crypto_ablkcipher_encrypt(subreq);
	if (err)
		goto out;

	if (giv != req->giv)
		eseqiv_complete2(req);

out:
	return err;
}

static void xennet_alloc_rx_buffers(struct net_device *dev)
{
	unsigned short id;
	struct netfront_info *np = netdev_priv(dev);
	struct sk_buff *skb;
	struct page *page;
	int i, batch_target, notify;
	RING_IDX req_prod = np->rx.req_prod_pvt;
	grant_ref_t ref;
	unsigned long pfn;
	void *vaddr;
	struct xen_netif_rx_request *req;

	if (unlikely(!netif_carrier_ok(dev)))
		return;

	/*
	 * Allocate skbuffs greedily, even though we batch updates to the
	 * receive ring. This creates a less bursty demand on the memory
	 * allocator, so should reduce the chance of failed allocation requests
	 * both for ourself and for other kernel subsystems.
	 */
	batch_target = np->rx_target - (req_prod - np->rx.rsp_cons);
	for (i = skb_queue_len(&np->rx_batch); i < batch_target; i++) {
		skb = __netdev_alloc_skb(dev, RX_COPY_THRESHOLD + NET_IP_ALIGN,
					 GFP_ATOMIC | __GFP_NOWARN);
		if (unlikely(!skb))
			goto no_skb;

		/* Align ip header to a 16 bytes boundary */
		skb_reserve(skb, NET_IP_ALIGN);

		page = alloc_page(GFP_ATOMIC | __GFP_NOWARN);
		if (!page) {
			kfree_skb(skb);
no_skb:
			/* Any skbuffs queued for refill? Force them out. */
			if (i != 0)
				goto refill;
			/* Could not allocate any skbuffs. Try again later. */
			mod_timer(&np->rx_refill_timer,
				  jiffies + (HZ/10));
			break;
		}

		__skb_fill_page_desc(skb, 0, page, 0, 0);
		skb_shinfo(skb)->nr_frags = 1;
		__skb_queue_tail(&np->rx_batch, skb);
	}

	/* Is the batch large enough to be worthwhile? */
	if (i < (np->rx_target/2)) {
		if (req_prod > np->rx.sring->req_prod)
			goto push;
		return;
	}

	/* Adjust our fill target if we risked running out of buffers. */
	if (((req_prod - np->rx.sring->rsp_prod) < (np->rx_target / 4)) &&
	    ((np->rx_target *= 2) > np->rx_max_target))
		np->rx_target = np->rx_max_target;

 refill:
	for (i = 0; ; i++) {
		skb = __skb_dequeue(&np->rx_batch);
		if (skb == NULL)
			break;

		skb->dev = dev;

		id = xennet_rxidx(req_prod + i);

		BUG_ON(np->rx_skbs[id]);
		np->rx_skbs[id] = skb;

		ref = gnttab_claim_grant_reference(&np->gref_rx_head);
		BUG_ON((signed short)ref < 0);
		np->grant_rx_ref[id] = ref;

		pfn = page_to_pfn(skb_frag_page(&skb_shinfo(skb)->frags[0]));
		vaddr = page_address(skb_frag_page(&skb_shinfo(skb)->frags[0]));

		req = RING_GET_REQUEST(&np->rx, req_prod + i);
		gnttab_grant_foreign_access_ref(ref,
						np->xbdev->otherend_id,
						pfn_to_mfn(pfn),
						0);

		req->id = id;
		req->gref = ref;
	}

	wmb();		/* barrier so backend seens requests */

	/* Above is a suitable barrier to ensure backend will see requests. */
	np->rx.req_prod_pvt = req_prod + i;
 push:
	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&np->rx, notify);
	if (notify)
		notify_remote_via_irq(np->netdev->irq);
//.........这里部分代码省略.........

/**
 * iwl_tx_cmd_complete - Pull unused buffers off the queue and reclaim them
 * @rxb: Rx buffer to reclaim
 * @handler_status: return value of the handler of the command
 *	(put in setup_rx_handlers)
 *
 * If an Rx buffer has an async callback associated with it the callback
 * will be executed.  The attached skb (if present) will only be freed
 * if the callback returns 1
 */
void iwl_tx_cmd_complete(struct iwl_trans *trans, struct iwl_rx_cmd_buffer *rxb,
			 int handler_status)
{
	struct iwl_rx_packet *pkt = rxb_addr(rxb);
	u16 sequence = le16_to_cpu(pkt->hdr.sequence);
	int txq_id = SEQ_TO_QUEUE(sequence);
	int index = SEQ_TO_INDEX(sequence);
	int cmd_index;
	struct iwl_device_cmd *cmd;
	struct iwl_cmd_meta *meta;
	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
	struct iwl_tx_queue *txq = &trans_pcie->txq[trans_pcie->cmd_queue];

	/* If a Tx command is being handled and it isn't in the actual
	 * command queue then there a command routing bug has been introduced
	 * in the queue management code. */
	if (WARN(txq_id != trans_pcie->cmd_queue,
		 "wrong command queue %d (should be %d), sequence 0x%X readp=%d writep=%d\n",
		  txq_id, trans_pcie->cmd_queue, sequence,
		  trans_pcie->txq[trans_pcie->cmd_queue].q.read_ptr,
		  trans_pcie->txq[trans_pcie->cmd_queue].q.write_ptr)) {
		iwl_print_hex_error(trans, pkt, 32);
		return;
	}

	spin_lock(&txq->lock);

	cmd_index = get_cmd_index(&txq->q, index);
	cmd = txq->cmd[cmd_index];
	meta = &txq->meta[cmd_index];

	txq->time_stamp = jiffies;

	iwlagn_unmap_tfd(trans, meta, &txq->tfds[index],
			 DMA_BIDIRECTIONAL);

	/* Input error checking is done when commands are added to queue. */
	if (meta->flags & CMD_WANT_SKB) {
		struct page *p = rxb_steal_page(rxb);

		meta->source->resp_pkt = pkt;
		meta->source->_rx_page_addr = (unsigned long)page_address(p);
		meta->source->_rx_page_order = hw_params(trans).rx_page_order;
		meta->source->handler_status = handler_status;
	}

	iwl_hcmd_queue_reclaim(trans, txq_id, index);

	if (!(meta->flags & CMD_ASYNC)) {
		if (!test_bit(STATUS_HCMD_ACTIVE, &trans->shrd->status)) {
			IWL_WARN(trans,
				 "HCMD_ACTIVE already clear for command %s\n",
				 get_cmd_string(cmd->hdr.cmd));
		}
		clear_bit(STATUS_HCMD_ACTIVE, &trans->shrd->status);
		IWL_DEBUG_INFO(trans, "Clearing HCMD_ACTIVE for command %s\n",
			       get_cmd_string(cmd->hdr.cmd));
		wake_up(&trans->wait_command_queue);
	}

	meta->flags = 0;

	spin_unlock(&txq->lock);
}

//.........这里部分代码省略.........
			}

		if (!P(blocks, disks)) {
			pq[0] = 0;
			dma_flags |= DMA_PREP_PQ_DISABLE_P;
		} else {
			pq[0] = dma_map_page(dev, P(blocks, disks),
					     offset, len,
					     DMA_TO_DEVICE);
			unmap->addr[j++] = pq[0];
			unmap->to_cnt++;
		}
		if (!Q(blocks, disks)) {
			pq[1] = 0;
			dma_flags |= DMA_PREP_PQ_DISABLE_Q;
		} else {
			pq[1] = dma_map_page(dev, Q(blocks, disks),
					     offset, len,
					     DMA_TO_DEVICE);
			unmap->addr[j++] = pq[1];
			unmap->to_cnt++;
		}

		if (submit->flags & ASYNC_TX_FENCE)
			dma_flags |= DMA_PREP_FENCE;
		for (;;) {
			tx = device->device_prep_dma_pq_val(chan, pq,
							    unmap->addr,
							    src_cnt,
							    coefs,
							    len, pqres,
							    dma_flags);
			if (likely(tx))
				break;
			async_tx_quiesce(&submit->depend_tx);
			dma_async_issue_pending(chan);
		}

		dma_set_unmap(tx, unmap);
		async_tx_submit(chan, tx, submit);

		return tx;
	} else {
		struct page *p_src = P(blocks, disks);
		struct page *q_src = Q(blocks, disks);
		enum async_tx_flags flags_orig = submit->flags;
		dma_async_tx_callback cb_fn_orig = submit->cb_fn;
		void *scribble = submit->scribble;
		void *cb_param_orig = submit->cb_param;
		void *p, *q, *s;

		pr_debug("%s: (sync) disks: %d len: %zu\n",
			 __func__, disks, len);

		/* caller must provide a temporary result buffer and
		 * allow the input parameters to be preserved
		 */
		BUG_ON(!spare || !scribble);

		/* wait for any prerequisite operations */
		async_tx_quiesce(&submit->depend_tx);

		/* recompute p and/or q into the temporary buffer and then
		 * check to see the result matches the current value
		 */
		tx = NULL;
		*pqres = 0;
		if (p_src) {
			init_async_submit(submit, ASYNC_TX_XOR_ZERO_DST, NULL,
					  NULL, NULL, scribble);
			tx = async_xor(spare, blocks, offset, disks-2, len, submit);
			async_tx_quiesce(&tx);
			p = page_address(p_src) + offset;
			s = page_address(spare) + offset;
			*pqres |= !!memcmp(p, s, len) << SUM_CHECK_P;
		}

		if (q_src) {
			P(blocks, disks) = NULL;
			Q(blocks, disks) = spare;
			init_async_submit(submit, 0, NULL, NULL, NULL, scribble);
			tx = async_gen_syndrome(blocks, offset, disks, len, submit);
			async_tx_quiesce(&tx);
			q = page_address(q_src) + offset;
			s = page_address(spare) + offset;
			*pqres |= !!memcmp(q, s, len) << SUM_CHECK_Q;
		}

		/* restore P, Q and submit */
		P(blocks, disks) = p_src;
		Q(blocks, disks) = q_src;

		submit->cb_fn = cb_fn_orig;
		submit->cb_param = cb_param_orig;
		submit->flags = flags_orig;
		async_tx_sync_epilog(submit);

		return NULL;
	}
}

static int page_is_zero(struct page *p, unsigned int offset, size_t len)
{
	return !memchr_inv(page_address(p) + offset, 0, len);
}

/*
 * inode->i_mutex: down
 */
int
reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
			  struct inode *inode, const char *name,
			  const void *buffer, size_t buffer_size, int flags)
{
	int err = 0;
	struct dentry *dentry;
	struct page *page;
	char *data;
	size_t file_pos = 0;
	size_t buffer_pos = 0;
	size_t new_size;
	__u32 xahash = 0;

	if (get_inode_sd_version(inode) == STAT_DATA_V1)
		return -EOPNOTSUPP;

	reiserfs_write_unlock(inode->i_sb);

	if (!buffer) {
		err = lookup_and_delete_xattr(inode, name);
		reiserfs_write_lock(inode->i_sb);
		return err;
	}

	dentry = xattr_lookup(inode, name, flags);
	if (IS_ERR(dentry)) {
		reiserfs_write_lock(inode->i_sb);
		return PTR_ERR(dentry);
	}

	down_write(&REISERFS_I(inode)->i_xattr_sem);

	reiserfs_write_lock(inode->i_sb);

	xahash = xattr_hash(buffer, buffer_size);
	while (buffer_pos < buffer_size || buffer_pos == 0) {
		size_t chunk;
		size_t skip = 0;
		size_t page_offset = (file_pos & (PAGE_CACHE_SIZE - 1));
		if (buffer_size - buffer_pos > PAGE_CACHE_SIZE)
			chunk = PAGE_CACHE_SIZE;
		else
			chunk = buffer_size - buffer_pos;

		page = reiserfs_get_page(dentry->d_inode, file_pos);
		if (IS_ERR(page)) {
			err = PTR_ERR(page);
			goto out_unlock;
		}

		lock_page(page);
		data = page_address(page);

		if (file_pos == 0) {
			struct reiserfs_xattr_header *rxh;
			skip = file_pos = sizeof(struct reiserfs_xattr_header);
			if (chunk + skip > PAGE_CACHE_SIZE)
				chunk = PAGE_CACHE_SIZE - skip;
			rxh = (struct reiserfs_xattr_header *)data;
			rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
			rxh->h_hash = cpu_to_le32(xahash);
		}

		err = __reiserfs_write_begin(page, page_offset, chunk + skip);
		if (!err) {
			if (buffer)
				memcpy(data + skip, buffer + buffer_pos, chunk);
			err = reiserfs_commit_write(NULL, page, page_offset,
						    page_offset + chunk +
						    skip);
		}
		unlock_page(page);
		reiserfs_put_page(page);
		buffer_pos += chunk;
		file_pos += chunk;
		skip = 0;
		if (err || buffer_size == 0 || !buffer)
			break;
	}

	new_size = buffer_size + sizeof(struct reiserfs_xattr_header);
	if (!err && new_size < i_size_read(dentry->d_inode)) {
		struct iattr newattrs = {
			.ia_ctime = current_fs_time(inode->i_sb),
			.ia_size = new_size,
			.ia_valid = ATTR_SIZE | ATTR_CTIME,
		};

		reiserfs_write_unlock(inode->i_sb);
		mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
		inode_dio_wait(dentry->d_inode);
		reiserfs_write_lock(inode->i_sb);

		err = reiserfs_setattr(dentry, &newattrs);
		mutex_unlock(&dentry->d_inode->i_mutex);
	} else
//.........这里部分代码省略.........

int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
			const void *value, size_t value_len, struct page *ipage)
{
	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
	struct f2fs_inode_info *fi = F2FS_I(inode);
	struct f2fs_xattr_header *header = NULL;
	struct f2fs_xattr_entry *here, *last;
	struct page *page;
	void *base_addr;
	int error, found, free, newsize;
	size_t name_len;
	char *pval;
	int ilock;

	if (name == NULL)
		return -EINVAL;

	if (value == NULL)
		value_len = 0;

	name_len = strlen(name);

	if (name_len > F2FS_NAME_LEN || value_len > MAX_VALUE_LEN)
		return -ERANGE;

	f2fs_balance_fs(sbi);

	ilock = mutex_lock_op(sbi);

	if (!fi->i_xattr_nid) {
		/* Allocate new attribute block */
		struct dnode_of_data dn;

		if (!alloc_nid(sbi, &fi->i_xattr_nid)) {
			error = -ENOSPC;
			goto exit;
		}
		set_new_dnode(&dn, inode, NULL, NULL, fi->i_xattr_nid);
		mark_inode_dirty(inode);

		page = new_node_page(&dn, XATTR_NODE_OFFSET, ipage);
		if (IS_ERR(page)) {
			alloc_nid_failed(sbi, fi->i_xattr_nid);
			fi->i_xattr_nid = 0;
			error = PTR_ERR(page);
			goto exit;
		}

		alloc_nid_done(sbi, fi->i_xattr_nid);
		base_addr = page_address(page);
		header = XATTR_HDR(base_addr);
		header->h_magic = cpu_to_le32(F2FS_XATTR_MAGIC);
		header->h_refcount = cpu_to_le32(1);
	} else {
		/* The inode already has an extended attribute block. */
		page = get_node_page(sbi, fi->i_xattr_nid);
		if (IS_ERR(page)) {
			error = PTR_ERR(page);
			goto exit;
		}

		base_addr = page_address(page);
		header = XATTR_HDR(base_addr);
	}

	if (le32_to_cpu(header->h_magic) != F2FS_XATTR_MAGIC) {
		error = -EIO;
		goto cleanup;
	}

	/* find entry with wanted name. */
	found = 0;
	list_for_each_xattr(here, base_addr) {
		if (here->e_name_index != name_index)
			continue;
		if (here->e_name_len != name_len)
			continue;
		if (!memcmp(here->e_name, name, name_len)) {
			found = 1;
			break;
		}
	}

	last = here;

	while (!IS_XATTR_LAST_ENTRY(last))
		last = XATTR_NEXT_ENTRY(last);

	newsize = XATTR_ALIGN(sizeof(struct f2fs_xattr_entry) +
			name_len + value_len);

	/* 1. Check space */
	if (value) {
		/* If value is NULL, it is remove operation.
		 * In case of update operation, we caculate free.
		 */
		free = MIN_OFFSET - ((char *)last - (char *)header);
		if (found)
			free = free - ENTRY_SIZE(here);

//.........这里部分代码省略.........

/*
 * inode->i_mutex: down
 */
int
reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer,
		   size_t buffer_size)
{
	ssize_t err = 0;
	struct dentry *dentry;
	size_t isize;
	size_t file_pos = 0;
	size_t buffer_pos = 0;
	struct page *page;
	__u32 hash = 0;

	if (name == NULL)
		return -EINVAL;

	/* We can't have xattrs attached to v1 items since they don't have
	 * generation numbers */
	if (get_inode_sd_version(inode) == STAT_DATA_V1)
		return -EOPNOTSUPP;

	dentry = xattr_lookup(inode, name, XATTR_REPLACE);
	if (IS_ERR(dentry)) {
		err = PTR_ERR(dentry);
		goto out;
	}

	down_read(&REISERFS_I(inode)->i_xattr_sem);

	isize = i_size_read(dentry->d_inode);

	/* Just return the size needed */
	if (buffer == NULL) {
		err = isize - sizeof(struct reiserfs_xattr_header);
		goto out_unlock;
	}

	if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
		err = -ERANGE;
		goto out_unlock;
	}

	while (file_pos < isize) {
		size_t chunk;
		char *data;
		size_t skip = 0;
		if (isize - file_pos > PAGE_CACHE_SIZE)
			chunk = PAGE_CACHE_SIZE;
		else
			chunk = isize - file_pos;

		page = reiserfs_get_page(dentry->d_inode, file_pos);
		if (IS_ERR(page)) {
			err = PTR_ERR(page);
			goto out_unlock;
		}

		lock_page(page);
		data = page_address(page);
		if (file_pos == 0) {
			struct reiserfs_xattr_header *rxh =
			    (struct reiserfs_xattr_header *)data;
			skip = file_pos = sizeof(struct reiserfs_xattr_header);
			chunk -= skip;
			/* Magic doesn't match up.. */
			if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
				unlock_page(page);
				reiserfs_put_page(page);
				reiserfs_warning(inode->i_sb, "jdm-20001",
						 "Invalid magic for xattr (%s) "
						 "associated with %k", name,
						 INODE_PKEY(inode));
				err = -EIO;
				goto out_unlock;
			}
			hash = le32_to_cpu(rxh->h_hash);
		}
		memcpy(buffer + buffer_pos, data + skip, chunk);
		unlock_page(page);
		reiserfs_put_page(page);
		file_pos += chunk;
		buffer_pos += chunk;
		skip = 0;
	}
	err = isize - sizeof(struct reiserfs_xattr_header);

	if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
	    hash) {
		reiserfs_warning(inode->i_sb, "jdm-20002",
				 "Invalid hash for xattr (%s) associated "
				 "with %k", name, INODE_PKEY(inode));
		err = -EIO;
	}

out_unlock:
	up_read(&REISERFS_I(inode)->i_xattr_sem);
	dput(dentry);

//.........这里部分代码省略.........