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https://github.com/edk2-porting/linux-next.git
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62a8067a7f
New variant of iov_iter - ITER_BVEC in iter->type, backed with bio_vec array instead of iovec one. Primitives taught to deal with such beasts, __swap_write() switched to using that kind of iov_iter. Note that bio_vec is just a <page, offset, length> triple - there's nothing block-specific about it. I've left the definition where it was, but took it from under ifdef CONFIG_BLOCK. Next target: ->splice_write()... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
117 lines
3.2 KiB
C
117 lines
3.2 KiB
C
/*
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* Berkeley style UIO structures - Alan Cox 1994.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef __LINUX_UIO_H
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#define __LINUX_UIO_H
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#include <linux/kernel.h>
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#include <uapi/linux/uio.h>
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struct page;
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struct kvec {
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void *iov_base; /* and that should *never* hold a userland pointer */
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size_t iov_len;
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};
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enum {
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ITER_IOVEC = 0,
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ITER_KVEC = 2,
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ITER_BVEC = 4,
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};
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struct iov_iter {
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int type;
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size_t iov_offset;
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size_t count;
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union {
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const struct iovec *iov;
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const struct bio_vec *bvec;
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};
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unsigned long nr_segs;
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};
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/*
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* Total number of bytes covered by an iovec.
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*
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* NOTE that it is not safe to use this function until all the iovec's
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* segment lengths have been validated. Because the individual lengths can
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* overflow a size_t when added together.
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*/
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static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
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{
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unsigned long seg;
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size_t ret = 0;
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for (seg = 0; seg < nr_segs; seg++)
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ret += iov[seg].iov_len;
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return ret;
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}
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static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
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{
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return (struct iovec) {
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.iov_base = iter->iov->iov_base + iter->iov_offset,
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.iov_len = min(iter->count,
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iter->iov->iov_len - iter->iov_offset),
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};
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}
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#define iov_for_each(iov, iter, start) \
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if (!((start).type & ITER_BVEC)) \
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for (iter = (start); \
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(iter).count && \
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((iov = iov_iter_iovec(&(iter))), 1); \
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iov_iter_advance(&(iter), (iov).iov_len))
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unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
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size_t iov_iter_copy_from_user_atomic(struct page *page,
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struct iov_iter *i, unsigned long offset, size_t bytes);
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void iov_iter_advance(struct iov_iter *i, size_t bytes);
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int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
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size_t iov_iter_single_seg_count(const struct iov_iter *i);
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size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
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struct iov_iter *i);
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size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
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struct iov_iter *i);
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unsigned long iov_iter_alignment(const struct iov_iter *i);
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void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
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unsigned long nr_segs, size_t count);
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ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
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size_t maxsize, size_t *start);
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ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
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size_t maxsize, size_t *start);
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int iov_iter_npages(const struct iov_iter *i, int maxpages);
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static inline size_t iov_iter_count(struct iov_iter *i)
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{
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return i->count;
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}
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static inline void iov_iter_truncate(struct iov_iter *i, size_t count)
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{
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if (i->count > count)
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i->count = count;
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}
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/*
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* reexpand a previously truncated iterator; count must be no more than how much
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* we had shrunk it.
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*/
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static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
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{
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i->count = count;
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}
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int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
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int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
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#endif
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