net/sunrpc/socklib.c

   1 /*
   2  * linux/net/sunrpc/socklib.c
   3  *
   4  * Common socket helper routines for RPC client and server
   5  *
   6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/compiler.h>
  10 #include <linux/netdevice.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/types.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/udp.h>
  15 #include <linux/sunrpc/xdr.h>
  16
  17
  18 /**
  19  * xdr_skb_read_bits - copy some data bits from skb to internal buffer
  20  * @desc: sk_buff copy helper
  21  * @to: copy destination
  22  * @len: number of bytes to copy
  23  *
  24  * Possibly called several times to iterate over an sk_buff and copy
  25  * data out of it.
  26  */
  27 size_t xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
  28 {
  29         if (len > desc->count)
  30                 len = desc->count;
  31         if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
  32                 return 0;
  33         desc->count -= len;
  34         desc->offset += len;
  35         return len;
  36 }
  37
  38 /**
  39  * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
  40  * @desc: sk_buff copy helper
  41  * @to: copy destination
  42  * @len: number of bytes to copy
  43  *
  44  * Same as skb_read_bits, but calculate a checksum at the same time.
  45  */
  46 static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
  47 {
  48         unsigned int pos;
  49         __wsum csum2;
  50
  51         if (len > desc->count)
  52                 len = desc->count;
  53         pos = desc->offset;
  54         csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len, 0);
  55         desc->csum = csum_block_add(desc->csum, csum2, pos);
  56         desc->count -= len;
  57         desc->offset += len;
  58         return len;
  59 }
  60
  61 /**
  62  * xdr_partial_copy_from_skb - copy data out of an skb
  63  * @xdr: target XDR buffer
  64  * @base: starting offset
  65  * @desc: sk_buff copy helper
  66  * @copy_actor: virtual method for copying data
  67  *
  68  */
  69 ssize_t xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
  70 {
  71         struct page     **ppage = xdr->pages;
  72         unsigned int    len, pglen = xdr->page_len;
  73         ssize_t         copied = 0;
  74         int             ret;
  75
  76         len = xdr->head[0].iov_len;
  77         if (base < len) {
  78                 len -= base;
  79                 ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
  80                 copied += ret;
  81                 if (ret != len || !desc->count)
  82                         goto out;
  83                 base = 0;
  84         } else
  85                 base -= len;
  86
  87         if (unlikely(pglen == 0))
  88                 goto copy_tail;
  89         if (unlikely(base >= pglen)) {
  90                 base -= pglen;
  91                 goto copy_tail;
  92         }
  93         if (base || xdr->page_base) {
  94                 pglen -= base;
  95                 base += xdr->page_base;
  96                 ppage += base >> PAGE_CACHE_SHIFT;
  97                 base &= ~PAGE_CACHE_MASK;
  98         }
  99         do {
 100                 char *kaddr;
 101
 102                 /* ACL likes to be lazy in allocating pages - ACLs
 103                  * are small by default but can get huge. */
 104                 if (unlikely(*ppage == NULL)) {
 105                         *ppage = alloc_page(GFP_ATOMIC);
 106                         if (unlikely(*ppage == NULL)) {
 107                                 if (copied == 0)
 108                                         copied = -ENOMEM;
 109                                 goto out;
 110                         }
 111                 }
 112
 113                 len = PAGE_CACHE_SIZE;
 114                 kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
 115                 if (base) {
 116                         len -= base;
 117                         if (pglen < len)
 118                                 len = pglen;
 119                         ret = copy_actor(desc, kaddr + base, len);
 120                         base = 0;
 121                 } else {
 122                         if (pglen < len)
 123                                 len = pglen;
 124                         ret = copy_actor(desc, kaddr, len);
 125                 }
 126                 flush_dcache_page(*ppage);
 127                 kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
 128                 copied += ret;
 129                 if (ret != len || !desc->count)
 130                         goto out;
 131                 ppage++;
 132         } while ((pglen -= len) != 0);
 133 copy_tail:
 134         len = xdr->tail[0].iov_len;
 135         if (base < len)
 136                 copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
 137 out:
 138         return copied;
 139 }
 140
 141 /**
 142  * csum_partial_copy_to_xdr - checksum and copy data
 143  * @xdr: target XDR buffer
 144  * @skb: source skb
 145  *
 146  * We have set things up such that we perform the checksum of the UDP
 147  * packet in parallel with the copies into the RPC client iovec.  -DaveM
 148  */
 149 int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 150 {
 151         struct xdr_skb_reader   desc;
 152
 153         desc.skb = skb;
 154         desc.offset = sizeof(struct udphdr);
 155         desc.count = skb->len - desc.offset;
 156
 157         if (skb->ip_summed == CHECKSUM_UNNECESSARY)
 158                 goto no_checksum;
 159
 160         desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
 161         if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
 162                 return -1;
 163         if (desc.offset != skb->len) {
 164                 __wsum csum2;
 165                 csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
 166                 desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
 167         }
 168         if (desc.count)
 169                 return -1;
 170         if (csum_fold(desc.csum))
 171                 return -1;
 172         if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
 173                 netdev_rx_csum_fault(skb->dev);
 174         return 0;
 175 no_checksum:
 176         if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
 177                 return -1;
 178         if (desc.count)
 179                 return -1;
 180         return 0;
 181 }