![Kirill A. Shutemov](/assets/img/avatar_default.png)
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
188 lines
4.5 KiB
C
188 lines
4.5 KiB
C
/*
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* linux/net/sunrpc/socklib.c
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*
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* Common socket helper routines for RPC client and server
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*
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* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
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*/
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#include <linux/compiler.h>
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#include <linux/netdevice.h>
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#include <linux/gfp.h>
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#include <linux/skbuff.h>
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#include <linux/types.h>
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#include <linux/pagemap.h>
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#include <linux/udp.h>
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#include <linux/sunrpc/xdr.h>
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#include <linux/export.h>
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/**
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* xdr_skb_read_bits - copy some data bits from skb to internal buffer
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* @desc: sk_buff copy helper
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* @to: copy destination
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* @len: number of bytes to copy
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*
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* Possibly called several times to iterate over an sk_buff and copy
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* data out of it.
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*/
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size_t xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
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{
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if (len > desc->count)
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len = desc->count;
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if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
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return 0;
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desc->count -= len;
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desc->offset += len;
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return len;
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}
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EXPORT_SYMBOL_GPL(xdr_skb_read_bits);
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/**
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* xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
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* @desc: sk_buff copy helper
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* @to: copy destination
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* @len: number of bytes to copy
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*
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* Same as skb_read_bits, but calculate a checksum at the same time.
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*/
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static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
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{
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unsigned int pos;
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__wsum csum2;
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if (len > desc->count)
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len = desc->count;
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pos = desc->offset;
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csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len, 0);
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desc->csum = csum_block_add(desc->csum, csum2, pos);
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desc->count -= len;
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desc->offset += len;
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return len;
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}
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/**
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* xdr_partial_copy_from_skb - copy data out of an skb
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* @xdr: target XDR buffer
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* @base: starting offset
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* @desc: sk_buff copy helper
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* @copy_actor: virtual method for copying data
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*
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*/
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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)
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{
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struct page **ppage = xdr->pages;
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unsigned int len, pglen = xdr->page_len;
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ssize_t copied = 0;
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size_t ret;
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len = xdr->head[0].iov_len;
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if (base < len) {
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len -= base;
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ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
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copied += ret;
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if (ret != len || !desc->count)
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goto out;
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base = 0;
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} else
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base -= len;
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if (unlikely(pglen == 0))
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goto copy_tail;
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if (unlikely(base >= pglen)) {
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base -= pglen;
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goto copy_tail;
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}
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if (base || xdr->page_base) {
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pglen -= base;
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base += xdr->page_base;
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ppage += base >> PAGE_SHIFT;
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base &= ~PAGE_MASK;
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}
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do {
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char *kaddr;
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/* ACL likes to be lazy in allocating pages - ACLs
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* are small by default but can get huge. */
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if (unlikely(*ppage == NULL)) {
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*ppage = alloc_page(GFP_ATOMIC);
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if (unlikely(*ppage == NULL)) {
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if (copied == 0)
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copied = -ENOMEM;
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goto out;
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}
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}
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len = PAGE_SIZE;
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kaddr = kmap_atomic(*ppage);
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if (base) {
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len -= base;
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if (pglen < len)
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len = pglen;
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ret = copy_actor(desc, kaddr + base, len);
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base = 0;
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} else {
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if (pglen < len)
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len = pglen;
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ret = copy_actor(desc, kaddr, len);
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}
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flush_dcache_page(*ppage);
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kunmap_atomic(kaddr);
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copied += ret;
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if (ret != len || !desc->count)
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goto out;
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ppage++;
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} while ((pglen -= len) != 0);
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copy_tail:
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len = xdr->tail[0].iov_len;
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if (base < len)
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copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
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out:
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return copied;
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}
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EXPORT_SYMBOL_GPL(xdr_partial_copy_from_skb);
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/**
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* csum_partial_copy_to_xdr - checksum and copy data
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* @xdr: target XDR buffer
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* @skb: source skb
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*
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* We have set things up such that we perform the checksum of the UDP
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* packet in parallel with the copies into the RPC client iovec. -DaveM
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*/
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int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
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{
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struct xdr_skb_reader desc;
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desc.skb = skb;
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desc.offset = sizeof(struct udphdr);
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desc.count = skb->len - desc.offset;
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if (skb_csum_unnecessary(skb))
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goto no_checksum;
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desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
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if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
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return -1;
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if (desc.offset != skb->len) {
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__wsum csum2;
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csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
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desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
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}
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if (desc.count)
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return -1;
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if (csum_fold(desc.csum))
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return -1;
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if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
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!skb->csum_complete_sw)
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netdev_rx_csum_fault(skb->dev);
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return 0;
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no_checksum:
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if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
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return -1;
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if (desc.count)
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return -1;
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return 0;
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}
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EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
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