95 lines
2.2 KiB
C
95 lines
2.2 KiB
C
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/*
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* linux/mm/filemap.h
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*
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* Copyright (C) 1994-1999 Linus Torvalds
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*/
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#ifndef __FILEMAP_H
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#define __FILEMAP_H
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/uio.h>
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#include <linux/config.h>
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#include <asm/uaccess.h>
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extern size_t
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__filemap_copy_from_user_iovec(char *vaddr,
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const struct iovec *iov,
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size_t base,
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size_t bytes);
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/*
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* Copy as much as we can into the page and return the number of bytes which
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* were sucessfully copied. If a fault is encountered then clear the page
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* out to (offset+bytes) and return the number of bytes which were copied.
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*/
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static inline size_t
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filemap_copy_from_user(struct page *page, unsigned long offset,
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const char __user *buf, unsigned bytes)
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{
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char *kaddr;
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int left;
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kaddr = kmap_atomic(page, KM_USER0);
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left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
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kunmap_atomic(kaddr, KM_USER0);
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if (left != 0) {
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/* Do it the slow way */
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kaddr = kmap(page);
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left = __copy_from_user(kaddr + offset, buf, bytes);
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kunmap(page);
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}
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return bytes - left;
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}
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/*
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* This has the same sideeffects and return value as filemap_copy_from_user().
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* The difference is that on a fault we need to memset the remainder of the
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* page (out to offset+bytes), to emulate filemap_copy_from_user()'s
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* single-segment behaviour.
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*/
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static inline size_t
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filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
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const struct iovec *iov, size_t base, size_t bytes)
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{
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char *kaddr;
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size_t copied;
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kaddr = kmap_atomic(page, KM_USER0);
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copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
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base, bytes);
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kunmap_atomic(kaddr, KM_USER0);
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if (copied != bytes) {
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kaddr = kmap(page);
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copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
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base, bytes);
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kunmap(page);
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}
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return copied;
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}
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static inline void
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filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
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{
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const struct iovec *iov = *iovp;
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size_t base = *basep;
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while (bytes) {
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int copy = min(bytes, iov->iov_len - base);
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bytes -= copy;
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base += copy;
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if (iov->iov_len == base) {
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iov++;
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base = 0;
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}
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}
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*iovp = iov;
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*basep = base;
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}
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#endif
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