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8fb0f47a9d
In an ideal world, when someone is passed an iov_iter and returns X bytes, then X bytes would have been consumed/advanced from the iov_iter. But we have use cases that always consume the entire iterator, a few examples of that are iomap and bdev O_DIRECT. This means we cannot rely on the state of the iov_iter once we've called ->read_iter() or ->write_iter(). This would be easier if we didn't always have to deal with truncate of the iov_iter, as rewinding would be trivial without that. We recently added a commit to track the truncate state, but that grew the iov_iter by 8 bytes and wasn't the best solution. Implement a helper to save enough of the iov_iter state to sanely restore it after we've called the read/write iterator helpers. This currently only works for IOVEC/BVEC/KVEC as that's all we need, support for other iterator types are left as an exercise for the reader. Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wiacKV4Gh-MYjteU0LwNBSGpWrK-Ov25HdqB1ewinrFPg@mail.gmail.com/ Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011 lines
48 KiB
C
2011 lines
48 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <crypto/hash.h>
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#include <linux/export.h>
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#include <linux/bvec.h>
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#include <linux/fault-inject-usercopy.h>
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#include <linux/uio.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/splice.h>
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#include <linux/compat.h>
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#include <net/checksum.h>
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#include <linux/scatterlist.h>
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#include <linux/instrumented.h>
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#define PIPE_PARANOIA /* for now */
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/* covers iovec and kvec alike */
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#define iterate_iovec(i, n, base, len, off, __p, STEP) { \
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size_t off = 0; \
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size_t skip = i->iov_offset; \
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do { \
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len = min(n, __p->iov_len - skip); \
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if (likely(len)) { \
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base = __p->iov_base + skip; \
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len -= (STEP); \
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off += len; \
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skip += len; \
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n -= len; \
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if (skip < __p->iov_len) \
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break; \
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} \
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__p++; \
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skip = 0; \
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} while (n); \
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i->iov_offset = skip; \
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n = off; \
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}
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#define iterate_bvec(i, n, base, len, off, p, STEP) { \
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size_t off = 0; \
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unsigned skip = i->iov_offset; \
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while (n) { \
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unsigned offset = p->bv_offset + skip; \
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unsigned left; \
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void *kaddr = kmap_local_page(p->bv_page + \
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offset / PAGE_SIZE); \
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base = kaddr + offset % PAGE_SIZE; \
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len = min(min(n, (size_t)(p->bv_len - skip)), \
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(size_t)(PAGE_SIZE - offset % PAGE_SIZE)); \
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left = (STEP); \
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kunmap_local(kaddr); \
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len -= left; \
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off += len; \
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skip += len; \
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if (skip == p->bv_len) { \
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skip = 0; \
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p++; \
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} \
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n -= len; \
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if (left) \
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break; \
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} \
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i->iov_offset = skip; \
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n = off; \
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}
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#define iterate_xarray(i, n, base, len, __off, STEP) { \
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__label__ __out; \
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size_t __off = 0; \
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struct page *head = NULL; \
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loff_t start = i->xarray_start + i->iov_offset; \
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unsigned offset = start % PAGE_SIZE; \
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pgoff_t index = start / PAGE_SIZE; \
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int j; \
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\
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XA_STATE(xas, i->xarray, index); \
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\
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rcu_read_lock(); \
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xas_for_each(&xas, head, ULONG_MAX) { \
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unsigned left; \
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if (xas_retry(&xas, head)) \
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continue; \
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if (WARN_ON(xa_is_value(head))) \
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break; \
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if (WARN_ON(PageHuge(head))) \
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break; \
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for (j = (head->index < index) ? index - head->index : 0; \
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j < thp_nr_pages(head); j++) { \
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void *kaddr = kmap_local_page(head + j); \
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base = kaddr + offset; \
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len = PAGE_SIZE - offset; \
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len = min(n, len); \
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left = (STEP); \
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kunmap_local(kaddr); \
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len -= left; \
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__off += len; \
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n -= len; \
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if (left || n == 0) \
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goto __out; \
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offset = 0; \
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} \
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} \
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__out: \
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rcu_read_unlock(); \
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i->iov_offset += __off; \
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n = __off; \
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}
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#define __iterate_and_advance(i, n, base, len, off, I, K) { \
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if (unlikely(i->count < n)) \
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n = i->count; \
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if (likely(n)) { \
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if (likely(iter_is_iovec(i))) { \
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const struct iovec *iov = i->iov; \
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void __user *base; \
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size_t len; \
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iterate_iovec(i, n, base, len, off, \
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iov, (I)) \
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i->nr_segs -= iov - i->iov; \
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i->iov = iov; \
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} else if (iov_iter_is_bvec(i)) { \
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const struct bio_vec *bvec = i->bvec; \
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void *base; \
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size_t len; \
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iterate_bvec(i, n, base, len, off, \
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bvec, (K)) \
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i->nr_segs -= bvec - i->bvec; \
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i->bvec = bvec; \
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} else if (iov_iter_is_kvec(i)) { \
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const struct kvec *kvec = i->kvec; \
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void *base; \
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size_t len; \
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iterate_iovec(i, n, base, len, off, \
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kvec, (K)) \
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i->nr_segs -= kvec - i->kvec; \
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i->kvec = kvec; \
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} else if (iov_iter_is_xarray(i)) { \
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void *base; \
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size_t len; \
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iterate_xarray(i, n, base, len, off, \
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(K)) \
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} \
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i->count -= n; \
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} \
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}
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#define iterate_and_advance(i, n, base, len, off, I, K) \
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__iterate_and_advance(i, n, base, len, off, I, ((void)(K),0))
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static int copyout(void __user *to, const void *from, size_t n)
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{
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if (should_fail_usercopy())
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return n;
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if (access_ok(to, n)) {
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instrument_copy_to_user(to, from, n);
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n = raw_copy_to_user(to, from, n);
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}
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return n;
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}
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static int copyin(void *to, const void __user *from, size_t n)
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{
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if (should_fail_usercopy())
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return n;
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if (access_ok(from, n)) {
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instrument_copy_from_user(to, from, n);
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n = raw_copy_from_user(to, from, n);
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}
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return n;
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}
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static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
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struct iov_iter *i)
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{
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size_t skip, copy, left, wanted;
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const struct iovec *iov;
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char __user *buf;
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void *kaddr, *from;
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if (unlikely(bytes > i->count))
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bytes = i->count;
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if (unlikely(!bytes))
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return 0;
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might_fault();
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wanted = bytes;
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iov = i->iov;
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skip = i->iov_offset;
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buf = iov->iov_base + skip;
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copy = min(bytes, iov->iov_len - skip);
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if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
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kaddr = kmap_atomic(page);
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from = kaddr + offset;
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/* first chunk, usually the only one */
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left = copyout(buf, from, copy);
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copy -= left;
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skip += copy;
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from += copy;
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bytes -= copy;
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while (unlikely(!left && bytes)) {
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iov++;
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buf = iov->iov_base;
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copy = min(bytes, iov->iov_len);
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left = copyout(buf, from, copy);
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copy -= left;
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skip = copy;
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from += copy;
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bytes -= copy;
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}
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if (likely(!bytes)) {
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kunmap_atomic(kaddr);
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goto done;
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}
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offset = from - kaddr;
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buf += copy;
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kunmap_atomic(kaddr);
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copy = min(bytes, iov->iov_len - skip);
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}
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/* Too bad - revert to non-atomic kmap */
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kaddr = kmap(page);
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from = kaddr + offset;
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left = copyout(buf, from, copy);
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copy -= left;
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skip += copy;
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from += copy;
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bytes -= copy;
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while (unlikely(!left && bytes)) {
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iov++;
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buf = iov->iov_base;
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copy = min(bytes, iov->iov_len);
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left = copyout(buf, from, copy);
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copy -= left;
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skip = copy;
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from += copy;
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bytes -= copy;
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}
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kunmap(page);
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done:
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if (skip == iov->iov_len) {
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iov++;
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skip = 0;
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}
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i->count -= wanted - bytes;
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i->nr_segs -= iov - i->iov;
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i->iov = iov;
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i->iov_offset = skip;
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return wanted - bytes;
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}
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static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
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struct iov_iter *i)
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{
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size_t skip, copy, left, wanted;
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const struct iovec *iov;
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char __user *buf;
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void *kaddr, *to;
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if (unlikely(bytes > i->count))
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bytes = i->count;
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if (unlikely(!bytes))
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return 0;
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might_fault();
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wanted = bytes;
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iov = i->iov;
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skip = i->iov_offset;
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buf = iov->iov_base + skip;
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copy = min(bytes, iov->iov_len - skip);
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if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
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kaddr = kmap_atomic(page);
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to = kaddr + offset;
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/* first chunk, usually the only one */
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left = copyin(to, buf, copy);
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copy -= left;
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skip += copy;
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to += copy;
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bytes -= copy;
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while (unlikely(!left && bytes)) {
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iov++;
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buf = iov->iov_base;
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copy = min(bytes, iov->iov_len);
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left = copyin(to, buf, copy);
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copy -= left;
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skip = copy;
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to += copy;
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bytes -= copy;
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}
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if (likely(!bytes)) {
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kunmap_atomic(kaddr);
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goto done;
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}
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offset = to - kaddr;
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buf += copy;
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kunmap_atomic(kaddr);
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copy = min(bytes, iov->iov_len - skip);
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}
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/* Too bad - revert to non-atomic kmap */
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kaddr = kmap(page);
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to = kaddr + offset;
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left = copyin(to, buf, copy);
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copy -= left;
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skip += copy;
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to += copy;
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bytes -= copy;
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while (unlikely(!left && bytes)) {
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iov++;
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buf = iov->iov_base;
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copy = min(bytes, iov->iov_len);
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left = copyin(to, buf, copy);
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copy -= left;
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skip = copy;
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to += copy;
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bytes -= copy;
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}
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kunmap(page);
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done:
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if (skip == iov->iov_len) {
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iov++;
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skip = 0;
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}
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i->count -= wanted - bytes;
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i->nr_segs -= iov - i->iov;
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i->iov = iov;
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i->iov_offset = skip;
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return wanted - bytes;
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}
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#ifdef PIPE_PARANOIA
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static bool sanity(const struct iov_iter *i)
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{
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struct pipe_inode_info *pipe = i->pipe;
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unsigned int p_head = pipe->head;
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unsigned int p_tail = pipe->tail;
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unsigned int p_mask = pipe->ring_size - 1;
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unsigned int p_occupancy = pipe_occupancy(p_head, p_tail);
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unsigned int i_head = i->head;
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unsigned int idx;
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if (i->iov_offset) {
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struct pipe_buffer *p;
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if (unlikely(p_occupancy == 0))
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goto Bad; // pipe must be non-empty
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if (unlikely(i_head != p_head - 1))
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goto Bad; // must be at the last buffer...
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p = &pipe->bufs[i_head & p_mask];
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if (unlikely(p->offset + p->len != i->iov_offset))
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goto Bad; // ... at the end of segment
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} else {
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if (i_head != p_head)
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goto Bad; // must be right after the last buffer
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}
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return true;
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Bad:
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printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset);
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printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n",
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p_head, p_tail, pipe->ring_size);
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for (idx = 0; idx < pipe->ring_size; idx++)
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printk(KERN_ERR "[%p %p %d %d]\n",
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pipe->bufs[idx].ops,
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pipe->bufs[idx].page,
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pipe->bufs[idx].offset,
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pipe->bufs[idx].len);
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WARN_ON(1);
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return false;
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}
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#else
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#define sanity(i) true
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#endif
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static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
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struct iov_iter *i)
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{
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struct pipe_inode_info *pipe = i->pipe;
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struct pipe_buffer *buf;
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unsigned int p_tail = pipe->tail;
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unsigned int p_mask = pipe->ring_size - 1;
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unsigned int i_head = i->head;
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size_t off;
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if (unlikely(bytes > i->count))
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bytes = i->count;
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if (unlikely(!bytes))
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return 0;
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if (!sanity(i))
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return 0;
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off = i->iov_offset;
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buf = &pipe->bufs[i_head & p_mask];
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if (off) {
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if (offset == off && buf->page == page) {
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/* merge with the last one */
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buf->len += bytes;
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i->iov_offset += bytes;
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goto out;
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}
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i_head++;
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buf = &pipe->bufs[i_head & p_mask];
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}
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if (pipe_full(i_head, p_tail, pipe->max_usage))
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return 0;
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buf->ops = &page_cache_pipe_buf_ops;
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get_page(page);
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buf->page = page;
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buf->offset = offset;
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buf->len = bytes;
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pipe->head = i_head + 1;
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i->iov_offset = offset + bytes;
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i->head = i_head;
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out:
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i->count -= bytes;
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return bytes;
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}
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/*
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* Fault in one or more iovecs of the given iov_iter, to a maximum length of
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* bytes. For each iovec, fault in each page that constitutes the iovec.
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*
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* Return 0 on success, or non-zero if the memory could not be accessed (i.e.
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* because it is an invalid address).
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*/
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int iov_iter_fault_in_readable(const struct iov_iter *i, size_t bytes)
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{
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if (iter_is_iovec(i)) {
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const struct iovec *p;
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size_t skip;
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if (bytes > i->count)
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bytes = i->count;
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for (p = i->iov, skip = i->iov_offset; bytes; p++, skip = 0) {
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size_t len = min(bytes, p->iov_len - skip);
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int err;
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if (unlikely(!len))
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continue;
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err = fault_in_pages_readable(p->iov_base + skip, len);
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if (unlikely(err))
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return err;
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bytes -= len;
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}
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}
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return 0;
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}
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EXPORT_SYMBOL(iov_iter_fault_in_readable);
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void iov_iter_init(struct iov_iter *i, unsigned int direction,
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const struct iovec *iov, unsigned long nr_segs,
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size_t count)
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{
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WARN_ON(direction & ~(READ | WRITE));
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*i = (struct iov_iter) {
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.iter_type = ITER_IOVEC,
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.data_source = direction,
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.iov = iov,
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.nr_segs = nr_segs,
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.iov_offset = 0,
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.count = count
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};
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}
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EXPORT_SYMBOL(iov_iter_init);
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static inline bool allocated(struct pipe_buffer *buf)
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{
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return buf->ops == &default_pipe_buf_ops;
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}
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static inline void data_start(const struct iov_iter *i,
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unsigned int *iter_headp, size_t *offp)
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{
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unsigned int p_mask = i->pipe->ring_size - 1;
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unsigned int iter_head = i->head;
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size_t off = i->iov_offset;
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if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) ||
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off == PAGE_SIZE)) {
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iter_head++;
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off = 0;
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}
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*iter_headp = iter_head;
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*offp = off;
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}
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|
|
|
static size_t push_pipe(struct iov_iter *i, size_t size,
|
|
int *iter_headp, size_t *offp)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_tail = pipe->tail;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
unsigned int iter_head;
|
|
size_t off;
|
|
ssize_t left;
|
|
|
|
if (unlikely(size > i->count))
|
|
size = i->count;
|
|
if (unlikely(!size))
|
|
return 0;
|
|
|
|
left = size;
|
|
data_start(i, &iter_head, &off);
|
|
*iter_headp = iter_head;
|
|
*offp = off;
|
|
if (off) {
|
|
left -= PAGE_SIZE - off;
|
|
if (left <= 0) {
|
|
pipe->bufs[iter_head & p_mask].len += size;
|
|
return size;
|
|
}
|
|
pipe->bufs[iter_head & p_mask].len = PAGE_SIZE;
|
|
iter_head++;
|
|
}
|
|
while (!pipe_full(iter_head, p_tail, pipe->max_usage)) {
|
|
struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask];
|
|
struct page *page = alloc_page(GFP_USER);
|
|
if (!page)
|
|
break;
|
|
|
|
buf->ops = &default_pipe_buf_ops;
|
|
buf->page = page;
|
|
buf->offset = 0;
|
|
buf->len = min_t(ssize_t, left, PAGE_SIZE);
|
|
left -= buf->len;
|
|
iter_head++;
|
|
pipe->head = iter_head;
|
|
|
|
if (left == 0)
|
|
return size;
|
|
}
|
|
return size - left;
|
|
}
|
|
|
|
static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
|
|
struct iov_iter *i)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
unsigned int i_head;
|
|
size_t n, off;
|
|
|
|
if (!sanity(i))
|
|
return 0;
|
|
|
|
bytes = n = push_pipe(i, bytes, &i_head, &off);
|
|
if (unlikely(!n))
|
|
return 0;
|
|
do {
|
|
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
|
|
memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk);
|
|
i->head = i_head;
|
|
i->iov_offset = off + chunk;
|
|
n -= chunk;
|
|
addr += chunk;
|
|
off = 0;
|
|
i_head++;
|
|
} while (n);
|
|
i->count -= bytes;
|
|
return bytes;
|
|
}
|
|
|
|
static __wsum csum_and_memcpy(void *to, const void *from, size_t len,
|
|
__wsum sum, size_t off)
|
|
{
|
|
__wsum next = csum_partial_copy_nocheck(from, to, len);
|
|
return csum_block_add(sum, next, off);
|
|
}
|
|
|
|
static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
|
|
struct iov_iter *i, __wsum *sump)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
__wsum sum = *sump;
|
|
size_t off = 0;
|
|
unsigned int i_head;
|
|
size_t r;
|
|
|
|
if (!sanity(i))
|
|
return 0;
|
|
|
|
bytes = push_pipe(i, bytes, &i_head, &r);
|
|
while (bytes) {
|
|
size_t chunk = min_t(size_t, bytes, PAGE_SIZE - r);
|
|
char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
|
|
sum = csum_and_memcpy(p + r, addr + off, chunk, sum, off);
|
|
kunmap_local(p);
|
|
i->head = i_head;
|
|
i->iov_offset = r + chunk;
|
|
bytes -= chunk;
|
|
off += chunk;
|
|
r = 0;
|
|
i_head++;
|
|
}
|
|
*sump = sum;
|
|
i->count -= off;
|
|
return off;
|
|
}
|
|
|
|
size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
|
|
{
|
|
if (unlikely(iov_iter_is_pipe(i)))
|
|
return copy_pipe_to_iter(addr, bytes, i);
|
|
if (iter_is_iovec(i))
|
|
might_fault();
|
|
iterate_and_advance(i, bytes, base, len, off,
|
|
copyout(base, addr + off, len),
|
|
memcpy(base, addr + off, len)
|
|
)
|
|
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL(_copy_to_iter);
|
|
|
|
#ifdef CONFIG_ARCH_HAS_COPY_MC
|
|
static int copyout_mc(void __user *to, const void *from, size_t n)
|
|
{
|
|
if (access_ok(to, n)) {
|
|
instrument_copy_to_user(to, from, n);
|
|
n = copy_mc_to_user((__force void *) to, from, n);
|
|
}
|
|
return n;
|
|
}
|
|
|
|
static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
|
|
struct iov_iter *i)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
unsigned int i_head;
|
|
size_t n, off, xfer = 0;
|
|
|
|
if (!sanity(i))
|
|
return 0;
|
|
|
|
n = push_pipe(i, bytes, &i_head, &off);
|
|
while (n) {
|
|
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
|
|
char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
|
|
unsigned long rem;
|
|
rem = copy_mc_to_kernel(p + off, addr + xfer, chunk);
|
|
chunk -= rem;
|
|
kunmap_local(p);
|
|
i->head = i_head;
|
|
i->iov_offset = off + chunk;
|
|
xfer += chunk;
|
|
if (rem)
|
|
break;
|
|
n -= chunk;
|
|
off = 0;
|
|
i_head++;
|
|
}
|
|
i->count -= xfer;
|
|
return xfer;
|
|
}
|
|
|
|
/**
|
|
* _copy_mc_to_iter - copy to iter with source memory error exception handling
|
|
* @addr: source kernel address
|
|
* @bytes: total transfer length
|
|
* @i: destination iterator
|
|
*
|
|
* The pmem driver deploys this for the dax operation
|
|
* (dax_copy_to_iter()) for dax reads (bypass page-cache and the
|
|
* block-layer). Upon #MC read(2) aborts and returns EIO or the bytes
|
|
* successfully copied.
|
|
*
|
|
* The main differences between this and typical _copy_to_iter().
|
|
*
|
|
* * Typical tail/residue handling after a fault retries the copy
|
|
* byte-by-byte until the fault happens again. Re-triggering machine
|
|
* checks is potentially fatal so the implementation uses source
|
|
* alignment and poison alignment assumptions to avoid re-triggering
|
|
* hardware exceptions.
|
|
*
|
|
* * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
|
|
* Compare to copy_to_iter() where only ITER_IOVEC attempts might return
|
|
* a short copy.
|
|
*
|
|
* Return: number of bytes copied (may be %0)
|
|
*/
|
|
size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
|
|
{
|
|
if (unlikely(iov_iter_is_pipe(i)))
|
|
return copy_mc_pipe_to_iter(addr, bytes, i);
|
|
if (iter_is_iovec(i))
|
|
might_fault();
|
|
__iterate_and_advance(i, bytes, base, len, off,
|
|
copyout_mc(base, addr + off, len),
|
|
copy_mc_to_kernel(base, addr + off, len)
|
|
)
|
|
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL_GPL(_copy_mc_to_iter);
|
|
#endif /* CONFIG_ARCH_HAS_COPY_MC */
|
|
|
|
size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
|
|
{
|
|
if (unlikely(iov_iter_is_pipe(i))) {
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
if (iter_is_iovec(i))
|
|
might_fault();
|
|
iterate_and_advance(i, bytes, base, len, off,
|
|
copyin(addr + off, base, len),
|
|
memcpy(addr + off, base, len)
|
|
)
|
|
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL(_copy_from_iter);
|
|
|
|
size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
|
|
{
|
|
if (unlikely(iov_iter_is_pipe(i))) {
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
iterate_and_advance(i, bytes, base, len, off,
|
|
__copy_from_user_inatomic_nocache(addr + off, base, len),
|
|
memcpy(addr + off, base, len)
|
|
)
|
|
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL(_copy_from_iter_nocache);
|
|
|
|
#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
|
|
/**
|
|
* _copy_from_iter_flushcache - write destination through cpu cache
|
|
* @addr: destination kernel address
|
|
* @bytes: total transfer length
|
|
* @i: source iterator
|
|
*
|
|
* The pmem driver arranges for filesystem-dax to use this facility via
|
|
* dax_copy_from_iter() for ensuring that writes to persistent memory
|
|
* are flushed through the CPU cache. It is differentiated from
|
|
* _copy_from_iter_nocache() in that guarantees all data is flushed for
|
|
* all iterator types. The _copy_from_iter_nocache() only attempts to
|
|
* bypass the cache for the ITER_IOVEC case, and on some archs may use
|
|
* instructions that strand dirty-data in the cache.
|
|
*
|
|
* Return: number of bytes copied (may be %0)
|
|
*/
|
|
size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
|
|
{
|
|
if (unlikely(iov_iter_is_pipe(i))) {
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
iterate_and_advance(i, bytes, base, len, off,
|
|
__copy_from_user_flushcache(addr + off, base, len),
|
|
memcpy_flushcache(addr + off, base, len)
|
|
)
|
|
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
|
|
#endif
|
|
|
|
static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
|
|
{
|
|
struct page *head;
|
|
size_t v = n + offset;
|
|
|
|
/*
|
|
* The general case needs to access the page order in order
|
|
* to compute the page size.
|
|
* However, we mostly deal with order-0 pages and thus can
|
|
* avoid a possible cache line miss for requests that fit all
|
|
* page orders.
|
|
*/
|
|
if (n <= v && v <= PAGE_SIZE)
|
|
return true;
|
|
|
|
head = compound_head(page);
|
|
v += (page - head) << PAGE_SHIFT;
|
|
|
|
if (likely(n <= v && v <= (page_size(head))))
|
|
return true;
|
|
WARN_ON(1);
|
|
return false;
|
|
}
|
|
|
|
static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
|
|
struct iov_iter *i)
|
|
{
|
|
if (likely(iter_is_iovec(i)))
|
|
return copy_page_to_iter_iovec(page, offset, bytes, i);
|
|
if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) {
|
|
void *kaddr = kmap_local_page(page);
|
|
size_t wanted = _copy_to_iter(kaddr + offset, bytes, i);
|
|
kunmap_local(kaddr);
|
|
return wanted;
|
|
}
|
|
if (iov_iter_is_pipe(i))
|
|
return copy_page_to_iter_pipe(page, offset, bytes, i);
|
|
if (unlikely(iov_iter_is_discard(i))) {
|
|
if (unlikely(i->count < bytes))
|
|
bytes = i->count;
|
|
i->count -= bytes;
|
|
return bytes;
|
|
}
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
|
|
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
|
|
struct iov_iter *i)
|
|
{
|
|
size_t res = 0;
|
|
if (unlikely(!page_copy_sane(page, offset, bytes)))
|
|
return 0;
|
|
page += offset / PAGE_SIZE; // first subpage
|
|
offset %= PAGE_SIZE;
|
|
while (1) {
|
|
size_t n = __copy_page_to_iter(page, offset,
|
|
min(bytes, (size_t)PAGE_SIZE - offset), i);
|
|
res += n;
|
|
bytes -= n;
|
|
if (!bytes || !n)
|
|
break;
|
|
offset += n;
|
|
if (offset == PAGE_SIZE) {
|
|
page++;
|
|
offset = 0;
|
|
}
|
|
}
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(copy_page_to_iter);
|
|
|
|
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
|
|
struct iov_iter *i)
|
|
{
|
|
if (unlikely(!page_copy_sane(page, offset, bytes)))
|
|
return 0;
|
|
if (likely(iter_is_iovec(i)))
|
|
return copy_page_from_iter_iovec(page, offset, bytes, i);
|
|
if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) {
|
|
void *kaddr = kmap_local_page(page);
|
|
size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
|
|
kunmap_local(kaddr);
|
|
return wanted;
|
|
}
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(copy_page_from_iter);
|
|
|
|
static size_t pipe_zero(size_t bytes, struct iov_iter *i)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
unsigned int i_head;
|
|
size_t n, off;
|
|
|
|
if (!sanity(i))
|
|
return 0;
|
|
|
|
bytes = n = push_pipe(i, bytes, &i_head, &off);
|
|
if (unlikely(!n))
|
|
return 0;
|
|
|
|
do {
|
|
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
|
|
char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
|
|
memset(p + off, 0, chunk);
|
|
kunmap_local(p);
|
|
i->head = i_head;
|
|
i->iov_offset = off + chunk;
|
|
n -= chunk;
|
|
off = 0;
|
|
i_head++;
|
|
} while (n);
|
|
i->count -= bytes;
|
|
return bytes;
|
|
}
|
|
|
|
size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
|
|
{
|
|
if (unlikely(iov_iter_is_pipe(i)))
|
|
return pipe_zero(bytes, i);
|
|
iterate_and_advance(i, bytes, base, len, count,
|
|
clear_user(base, len),
|
|
memset(base, 0, len)
|
|
)
|
|
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_zero);
|
|
|
|
size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes,
|
|
struct iov_iter *i)
|
|
{
|
|
char *kaddr = kmap_atomic(page), *p = kaddr + offset;
|
|
if (unlikely(!page_copy_sane(page, offset, bytes))) {
|
|
kunmap_atomic(kaddr);
|
|
return 0;
|
|
}
|
|
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
|
|
kunmap_atomic(kaddr);
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
iterate_and_advance(i, bytes, base, len, off,
|
|
copyin(p + off, base, len),
|
|
memcpy(p + off, base, len)
|
|
)
|
|
kunmap_atomic(kaddr);
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL(copy_page_from_iter_atomic);
|
|
|
|
static inline void pipe_truncate(struct iov_iter *i)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_tail = pipe->tail;
|
|
unsigned int p_head = pipe->head;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
|
|
if (!pipe_empty(p_head, p_tail)) {
|
|
struct pipe_buffer *buf;
|
|
unsigned int i_head = i->head;
|
|
size_t off = i->iov_offset;
|
|
|
|
if (off) {
|
|
buf = &pipe->bufs[i_head & p_mask];
|
|
buf->len = off - buf->offset;
|
|
i_head++;
|
|
}
|
|
while (p_head != i_head) {
|
|
p_head--;
|
|
pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]);
|
|
}
|
|
|
|
pipe->head = p_head;
|
|
}
|
|
}
|
|
|
|
static void pipe_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
if (size) {
|
|
struct pipe_buffer *buf;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
unsigned int i_head = i->head;
|
|
size_t off = i->iov_offset, left = size;
|
|
|
|
if (off) /* make it relative to the beginning of buffer */
|
|
left += off - pipe->bufs[i_head & p_mask].offset;
|
|
while (1) {
|
|
buf = &pipe->bufs[i_head & p_mask];
|
|
if (left <= buf->len)
|
|
break;
|
|
left -= buf->len;
|
|
i_head++;
|
|
}
|
|
i->head = i_head;
|
|
i->iov_offset = buf->offset + left;
|
|
}
|
|
i->count -= size;
|
|
/* ... and discard everything past that point */
|
|
pipe_truncate(i);
|
|
}
|
|
|
|
static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
struct bvec_iter bi;
|
|
|
|
bi.bi_size = i->count;
|
|
bi.bi_bvec_done = i->iov_offset;
|
|
bi.bi_idx = 0;
|
|
bvec_iter_advance(i->bvec, &bi, size);
|
|
|
|
i->bvec += bi.bi_idx;
|
|
i->nr_segs -= bi.bi_idx;
|
|
i->count = bi.bi_size;
|
|
i->iov_offset = bi.bi_bvec_done;
|
|
}
|
|
|
|
static void iov_iter_iovec_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
const struct iovec *iov, *end;
|
|
|
|
if (!i->count)
|
|
return;
|
|
i->count -= size;
|
|
|
|
size += i->iov_offset; // from beginning of current segment
|
|
for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) {
|
|
if (likely(size < iov->iov_len))
|
|
break;
|
|
size -= iov->iov_len;
|
|
}
|
|
i->iov_offset = size;
|
|
i->nr_segs -= iov - i->iov;
|
|
i->iov = iov;
|
|
}
|
|
|
|
void iov_iter_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
if (unlikely(i->count < size))
|
|
size = i->count;
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) {
|
|
/* iovec and kvec have identical layouts */
|
|
iov_iter_iovec_advance(i, size);
|
|
} else if (iov_iter_is_bvec(i)) {
|
|
iov_iter_bvec_advance(i, size);
|
|
} else if (iov_iter_is_pipe(i)) {
|
|
pipe_advance(i, size);
|
|
} else if (unlikely(iov_iter_is_xarray(i))) {
|
|
i->iov_offset += size;
|
|
i->count -= size;
|
|
} else if (iov_iter_is_discard(i)) {
|
|
i->count -= size;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_advance);
|
|
|
|
void iov_iter_revert(struct iov_iter *i, size_t unroll)
|
|
{
|
|
if (!unroll)
|
|
return;
|
|
if (WARN_ON(unroll > MAX_RW_COUNT))
|
|
return;
|
|
i->count += unroll;
|
|
if (unlikely(iov_iter_is_pipe(i))) {
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
unsigned int i_head = i->head;
|
|
size_t off = i->iov_offset;
|
|
while (1) {
|
|
struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
|
|
size_t n = off - b->offset;
|
|
if (unroll < n) {
|
|
off -= unroll;
|
|
break;
|
|
}
|
|
unroll -= n;
|
|
if (!unroll && i_head == i->start_head) {
|
|
off = 0;
|
|
break;
|
|
}
|
|
i_head--;
|
|
b = &pipe->bufs[i_head & p_mask];
|
|
off = b->offset + b->len;
|
|
}
|
|
i->iov_offset = off;
|
|
i->head = i_head;
|
|
pipe_truncate(i);
|
|
return;
|
|
}
|
|
if (unlikely(iov_iter_is_discard(i)))
|
|
return;
|
|
if (unroll <= i->iov_offset) {
|
|
i->iov_offset -= unroll;
|
|
return;
|
|
}
|
|
unroll -= i->iov_offset;
|
|
if (iov_iter_is_xarray(i)) {
|
|
BUG(); /* We should never go beyond the start of the specified
|
|
* range since we might then be straying into pages that
|
|
* aren't pinned.
|
|
*/
|
|
} else if (iov_iter_is_bvec(i)) {
|
|
const struct bio_vec *bvec = i->bvec;
|
|
while (1) {
|
|
size_t n = (--bvec)->bv_len;
|
|
i->nr_segs++;
|
|
if (unroll <= n) {
|
|
i->bvec = bvec;
|
|
i->iov_offset = n - unroll;
|
|
return;
|
|
}
|
|
unroll -= n;
|
|
}
|
|
} else { /* same logics for iovec and kvec */
|
|
const struct iovec *iov = i->iov;
|
|
while (1) {
|
|
size_t n = (--iov)->iov_len;
|
|
i->nr_segs++;
|
|
if (unroll <= n) {
|
|
i->iov = iov;
|
|
i->iov_offset = n - unroll;
|
|
return;
|
|
}
|
|
unroll -= n;
|
|
}
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_revert);
|
|
|
|
/*
|
|
* Return the count of just the current iov_iter segment.
|
|
*/
|
|
size_t iov_iter_single_seg_count(const struct iov_iter *i)
|
|
{
|
|
if (i->nr_segs > 1) {
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
|
|
return min(i->count, i->iov->iov_len - i->iov_offset);
|
|
if (iov_iter_is_bvec(i))
|
|
return min(i->count, i->bvec->bv_len - i->iov_offset);
|
|
}
|
|
return i->count;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_single_seg_count);
|
|
|
|
void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
|
|
const struct kvec *kvec, unsigned long nr_segs,
|
|
size_t count)
|
|
{
|
|
WARN_ON(direction & ~(READ | WRITE));
|
|
*i = (struct iov_iter){
|
|
.iter_type = ITER_KVEC,
|
|
.data_source = direction,
|
|
.kvec = kvec,
|
|
.nr_segs = nr_segs,
|
|
.iov_offset = 0,
|
|
.count = count
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_kvec);
|
|
|
|
void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
|
|
const struct bio_vec *bvec, unsigned long nr_segs,
|
|
size_t count)
|
|
{
|
|
WARN_ON(direction & ~(READ | WRITE));
|
|
*i = (struct iov_iter){
|
|
.iter_type = ITER_BVEC,
|
|
.data_source = direction,
|
|
.bvec = bvec,
|
|
.nr_segs = nr_segs,
|
|
.iov_offset = 0,
|
|
.count = count
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_bvec);
|
|
|
|
void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
|
|
struct pipe_inode_info *pipe,
|
|
size_t count)
|
|
{
|
|
BUG_ON(direction != READ);
|
|
WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size));
|
|
*i = (struct iov_iter){
|
|
.iter_type = ITER_PIPE,
|
|
.data_source = false,
|
|
.pipe = pipe,
|
|
.head = pipe->head,
|
|
.start_head = pipe->head,
|
|
.iov_offset = 0,
|
|
.count = count
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_pipe);
|
|
|
|
/**
|
|
* iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray
|
|
* @i: The iterator to initialise.
|
|
* @direction: The direction of the transfer.
|
|
* @xarray: The xarray to access.
|
|
* @start: The start file position.
|
|
* @count: The size of the I/O buffer in bytes.
|
|
*
|
|
* Set up an I/O iterator to either draw data out of the pages attached to an
|
|
* inode or to inject data into those pages. The pages *must* be prevented
|
|
* from evaporation, either by taking a ref on them or locking them by the
|
|
* caller.
|
|
*/
|
|
void iov_iter_xarray(struct iov_iter *i, unsigned int direction,
|
|
struct xarray *xarray, loff_t start, size_t count)
|
|
{
|
|
BUG_ON(direction & ~1);
|
|
*i = (struct iov_iter) {
|
|
.iter_type = ITER_XARRAY,
|
|
.data_source = direction,
|
|
.xarray = xarray,
|
|
.xarray_start = start,
|
|
.count = count,
|
|
.iov_offset = 0
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_xarray);
|
|
|
|
/**
|
|
* iov_iter_discard - Initialise an I/O iterator that discards data
|
|
* @i: The iterator to initialise.
|
|
* @direction: The direction of the transfer.
|
|
* @count: The size of the I/O buffer in bytes.
|
|
*
|
|
* Set up an I/O iterator that just discards everything that's written to it.
|
|
* It's only available as a READ iterator.
|
|
*/
|
|
void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
|
|
{
|
|
BUG_ON(direction != READ);
|
|
*i = (struct iov_iter){
|
|
.iter_type = ITER_DISCARD,
|
|
.data_source = false,
|
|
.count = count,
|
|
.iov_offset = 0
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_discard);
|
|
|
|
static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)
|
|
{
|
|
unsigned long res = 0;
|
|
size_t size = i->count;
|
|
size_t skip = i->iov_offset;
|
|
unsigned k;
|
|
|
|
for (k = 0; k < i->nr_segs; k++, skip = 0) {
|
|
size_t len = i->iov[k].iov_len - skip;
|
|
if (len) {
|
|
res |= (unsigned long)i->iov[k].iov_base + skip;
|
|
if (len > size)
|
|
len = size;
|
|
res |= len;
|
|
size -= len;
|
|
if (!size)
|
|
break;
|
|
}
|
|
}
|
|
return res;
|
|
}
|
|
|
|
static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i)
|
|
{
|
|
unsigned res = 0;
|
|
size_t size = i->count;
|
|
unsigned skip = i->iov_offset;
|
|
unsigned k;
|
|
|
|
for (k = 0; k < i->nr_segs; k++, skip = 0) {
|
|
size_t len = i->bvec[k].bv_len - skip;
|
|
res |= (unsigned long)i->bvec[k].bv_offset + skip;
|
|
if (len > size)
|
|
len = size;
|
|
res |= len;
|
|
size -= len;
|
|
if (!size)
|
|
break;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
unsigned long iov_iter_alignment(const struct iov_iter *i)
|
|
{
|
|
/* iovec and kvec have identical layouts */
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
|
|
return iov_iter_alignment_iovec(i);
|
|
|
|
if (iov_iter_is_bvec(i))
|
|
return iov_iter_alignment_bvec(i);
|
|
|
|
if (iov_iter_is_pipe(i)) {
|
|
unsigned int p_mask = i->pipe->ring_size - 1;
|
|
size_t size = i->count;
|
|
|
|
if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
|
|
return size | i->iov_offset;
|
|
return size;
|
|
}
|
|
|
|
if (iov_iter_is_xarray(i))
|
|
return (i->xarray_start + i->iov_offset) | i->count;
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_alignment);
|
|
|
|
unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
|
|
{
|
|
unsigned long res = 0;
|
|
unsigned long v = 0;
|
|
size_t size = i->count;
|
|
unsigned k;
|
|
|
|
if (WARN_ON(!iter_is_iovec(i)))
|
|
return ~0U;
|
|
|
|
for (k = 0; k < i->nr_segs; k++) {
|
|
if (i->iov[k].iov_len) {
|
|
unsigned long base = (unsigned long)i->iov[k].iov_base;
|
|
if (v) // if not the first one
|
|
res |= base | v; // this start | previous end
|
|
v = base + i->iov[k].iov_len;
|
|
if (size <= i->iov[k].iov_len)
|
|
break;
|
|
size -= i->iov[k].iov_len;
|
|
}
|
|
}
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_gap_alignment);
|
|
|
|
static inline ssize_t __pipe_get_pages(struct iov_iter *i,
|
|
size_t maxsize,
|
|
struct page **pages,
|
|
int iter_head,
|
|
size_t *start)
|
|
{
|
|
struct pipe_inode_info *pipe = i->pipe;
|
|
unsigned int p_mask = pipe->ring_size - 1;
|
|
ssize_t n = push_pipe(i, maxsize, &iter_head, start);
|
|
if (!n)
|
|
return -EFAULT;
|
|
|
|
maxsize = n;
|
|
n += *start;
|
|
while (n > 0) {
|
|
get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
|
|
iter_head++;
|
|
n -= PAGE_SIZE;
|
|
}
|
|
|
|
return maxsize;
|
|
}
|
|
|
|
static ssize_t pipe_get_pages(struct iov_iter *i,
|
|
struct page **pages, size_t maxsize, unsigned maxpages,
|
|
size_t *start)
|
|
{
|
|
unsigned int iter_head, npages;
|
|
size_t capacity;
|
|
|
|
if (!sanity(i))
|
|
return -EFAULT;
|
|
|
|
data_start(i, &iter_head, start);
|
|
/* Amount of free space: some of this one + all after this one */
|
|
npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
|
|
capacity = min(npages, maxpages) * PAGE_SIZE - *start;
|
|
|
|
return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
|
|
}
|
|
|
|
static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
|
|
pgoff_t index, unsigned int nr_pages)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
struct page *page;
|
|
unsigned int ret = 0;
|
|
|
|
rcu_read_lock();
|
|
for (page = xas_load(&xas); page; page = xas_next(&xas)) {
|
|
if (xas_retry(&xas, page))
|
|
continue;
|
|
|
|
/* Has the page moved or been split? */
|
|
if (unlikely(page != xas_reload(&xas))) {
|
|
xas_reset(&xas);
|
|
continue;
|
|
}
|
|
|
|
pages[ret] = find_subpage(page, xas.xa_index);
|
|
get_page(pages[ret]);
|
|
if (++ret == nr_pages)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t iter_xarray_get_pages(struct iov_iter *i,
|
|
struct page **pages, size_t maxsize,
|
|
unsigned maxpages, size_t *_start_offset)
|
|
{
|
|
unsigned nr, offset;
|
|
pgoff_t index, count;
|
|
size_t size = maxsize, actual;
|
|
loff_t pos;
|
|
|
|
if (!size || !maxpages)
|
|
return 0;
|
|
|
|
pos = i->xarray_start + i->iov_offset;
|
|
index = pos >> PAGE_SHIFT;
|
|
offset = pos & ~PAGE_MASK;
|
|
*_start_offset = offset;
|
|
|
|
count = 1;
|
|
if (size > PAGE_SIZE - offset) {
|
|
size -= PAGE_SIZE - offset;
|
|
count += size >> PAGE_SHIFT;
|
|
size &= ~PAGE_MASK;
|
|
if (size)
|
|
count++;
|
|
}
|
|
|
|
if (count > maxpages)
|
|
count = maxpages;
|
|
|
|
nr = iter_xarray_populate_pages(pages, i->xarray, index, count);
|
|
if (nr == 0)
|
|
return 0;
|
|
|
|
actual = PAGE_SIZE * nr;
|
|
actual -= offset;
|
|
if (nr == count && size > 0) {
|
|
unsigned last_offset = (nr > 1) ? 0 : offset;
|
|
actual -= PAGE_SIZE - (last_offset + size);
|
|
}
|
|
return actual;
|
|
}
|
|
|
|
/* must be done on non-empty ITER_IOVEC one */
|
|
static unsigned long first_iovec_segment(const struct iov_iter *i,
|
|
size_t *size, size_t *start,
|
|
size_t maxsize, unsigned maxpages)
|
|
{
|
|
size_t skip;
|
|
long k;
|
|
|
|
for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) {
|
|
unsigned long addr = (unsigned long)i->iov[k].iov_base + skip;
|
|
size_t len = i->iov[k].iov_len - skip;
|
|
|
|
if (unlikely(!len))
|
|
continue;
|
|
if (len > maxsize)
|
|
len = maxsize;
|
|
len += (*start = addr % PAGE_SIZE);
|
|
if (len > maxpages * PAGE_SIZE)
|
|
len = maxpages * PAGE_SIZE;
|
|
*size = len;
|
|
return addr & PAGE_MASK;
|
|
}
|
|
BUG(); // if it had been empty, we wouldn't get called
|
|
}
|
|
|
|
/* must be done on non-empty ITER_BVEC one */
|
|
static struct page *first_bvec_segment(const struct iov_iter *i,
|
|
size_t *size, size_t *start,
|
|
size_t maxsize, unsigned maxpages)
|
|
{
|
|
struct page *page;
|
|
size_t skip = i->iov_offset, len;
|
|
|
|
len = i->bvec->bv_len - skip;
|
|
if (len > maxsize)
|
|
len = maxsize;
|
|
skip += i->bvec->bv_offset;
|
|
page = i->bvec->bv_page + skip / PAGE_SIZE;
|
|
len += (*start = skip % PAGE_SIZE);
|
|
if (len > maxpages * PAGE_SIZE)
|
|
len = maxpages * PAGE_SIZE;
|
|
*size = len;
|
|
return page;
|
|
}
|
|
|
|
ssize_t iov_iter_get_pages(struct iov_iter *i,
|
|
struct page **pages, size_t maxsize, unsigned maxpages,
|
|
size_t *start)
|
|
{
|
|
size_t len;
|
|
int n, res;
|
|
|
|
if (maxsize > i->count)
|
|
maxsize = i->count;
|
|
if (!maxsize)
|
|
return 0;
|
|
|
|
if (likely(iter_is_iovec(i))) {
|
|
unsigned long addr;
|
|
|
|
addr = first_iovec_segment(i, &len, start, maxsize, maxpages);
|
|
n = DIV_ROUND_UP(len, PAGE_SIZE);
|
|
res = get_user_pages_fast(addr, n,
|
|
iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0,
|
|
pages);
|
|
if (unlikely(res < 0))
|
|
return res;
|
|
return (res == n ? len : res * PAGE_SIZE) - *start;
|
|
}
|
|
if (iov_iter_is_bvec(i)) {
|
|
struct page *page;
|
|
|
|
page = first_bvec_segment(i, &len, start, maxsize, maxpages);
|
|
n = DIV_ROUND_UP(len, PAGE_SIZE);
|
|
while (n--)
|
|
get_page(*pages++ = page++);
|
|
return len - *start;
|
|
}
|
|
if (iov_iter_is_pipe(i))
|
|
return pipe_get_pages(i, pages, maxsize, maxpages, start);
|
|
if (iov_iter_is_xarray(i))
|
|
return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
|
|
return -EFAULT;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_get_pages);
|
|
|
|
static struct page **get_pages_array(size_t n)
|
|
{
|
|
return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
|
|
}
|
|
|
|
static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
size_t *start)
|
|
{
|
|
struct page **p;
|
|
unsigned int iter_head, npages;
|
|
ssize_t n;
|
|
|
|
if (!sanity(i))
|
|
return -EFAULT;
|
|
|
|
data_start(i, &iter_head, start);
|
|
/* Amount of free space: some of this one + all after this one */
|
|
npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
|
|
n = npages * PAGE_SIZE - *start;
|
|
if (maxsize > n)
|
|
maxsize = n;
|
|
else
|
|
npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
|
|
p = get_pages_array(npages);
|
|
if (!p)
|
|
return -ENOMEM;
|
|
n = __pipe_get_pages(i, maxsize, p, iter_head, start);
|
|
if (n > 0)
|
|
*pages = p;
|
|
else
|
|
kvfree(p);
|
|
return n;
|
|
}
|
|
|
|
static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
size_t *_start_offset)
|
|
{
|
|
struct page **p;
|
|
unsigned nr, offset;
|
|
pgoff_t index, count;
|
|
size_t size = maxsize, actual;
|
|
loff_t pos;
|
|
|
|
if (!size)
|
|
return 0;
|
|
|
|
pos = i->xarray_start + i->iov_offset;
|
|
index = pos >> PAGE_SHIFT;
|
|
offset = pos & ~PAGE_MASK;
|
|
*_start_offset = offset;
|
|
|
|
count = 1;
|
|
if (size > PAGE_SIZE - offset) {
|
|
size -= PAGE_SIZE - offset;
|
|
count += size >> PAGE_SHIFT;
|
|
size &= ~PAGE_MASK;
|
|
if (size)
|
|
count++;
|
|
}
|
|
|
|
p = get_pages_array(count);
|
|
if (!p)
|
|
return -ENOMEM;
|
|
*pages = p;
|
|
|
|
nr = iter_xarray_populate_pages(p, i->xarray, index, count);
|
|
if (nr == 0)
|
|
return 0;
|
|
|
|
actual = PAGE_SIZE * nr;
|
|
actual -= offset;
|
|
if (nr == count && size > 0) {
|
|
unsigned last_offset = (nr > 1) ? 0 : offset;
|
|
actual -= PAGE_SIZE - (last_offset + size);
|
|
}
|
|
return actual;
|
|
}
|
|
|
|
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
size_t *start)
|
|
{
|
|
struct page **p;
|
|
size_t len;
|
|
int n, res;
|
|
|
|
if (maxsize > i->count)
|
|
maxsize = i->count;
|
|
if (!maxsize)
|
|
return 0;
|
|
|
|
if (likely(iter_is_iovec(i))) {
|
|
unsigned long addr;
|
|
|
|
addr = first_iovec_segment(i, &len, start, maxsize, ~0U);
|
|
n = DIV_ROUND_UP(len, PAGE_SIZE);
|
|
p = get_pages_array(n);
|
|
if (!p)
|
|
return -ENOMEM;
|
|
res = get_user_pages_fast(addr, n,
|
|
iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p);
|
|
if (unlikely(res < 0)) {
|
|
kvfree(p);
|
|
return res;
|
|
}
|
|
*pages = p;
|
|
return (res == n ? len : res * PAGE_SIZE) - *start;
|
|
}
|
|
if (iov_iter_is_bvec(i)) {
|
|
struct page *page;
|
|
|
|
page = first_bvec_segment(i, &len, start, maxsize, ~0U);
|
|
n = DIV_ROUND_UP(len, PAGE_SIZE);
|
|
*pages = p = get_pages_array(n);
|
|
if (!p)
|
|
return -ENOMEM;
|
|
while (n--)
|
|
get_page(*p++ = page++);
|
|
return len - *start;
|
|
}
|
|
if (iov_iter_is_pipe(i))
|
|
return pipe_get_pages_alloc(i, pages, maxsize, start);
|
|
if (iov_iter_is_xarray(i))
|
|
return iter_xarray_get_pages_alloc(i, pages, maxsize, start);
|
|
return -EFAULT;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_get_pages_alloc);
|
|
|
|
size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
|
|
struct iov_iter *i)
|
|
{
|
|
__wsum sum, next;
|
|
sum = *csum;
|
|
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
iterate_and_advance(i, bytes, base, len, off, ({
|
|
next = csum_and_copy_from_user(base, addr + off, len);
|
|
sum = csum_block_add(sum, next, off);
|
|
next ? 0 : len;
|
|
}), ({
|
|
sum = csum_and_memcpy(addr + off, base, len, sum, off);
|
|
})
|
|
)
|
|
*csum = sum;
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL(csum_and_copy_from_iter);
|
|
|
|
size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
|
|
struct iov_iter *i)
|
|
{
|
|
struct csum_state *csstate = _csstate;
|
|
__wsum sum, next;
|
|
|
|
if (unlikely(iov_iter_is_discard(i))) {
|
|
WARN_ON(1); /* for now */
|
|
return 0;
|
|
}
|
|
|
|
sum = csum_shift(csstate->csum, csstate->off);
|
|
if (unlikely(iov_iter_is_pipe(i)))
|
|
bytes = csum_and_copy_to_pipe_iter(addr, bytes, i, &sum);
|
|
else iterate_and_advance(i, bytes, base, len, off, ({
|
|
next = csum_and_copy_to_user(addr + off, base, len);
|
|
sum = csum_block_add(sum, next, off);
|
|
next ? 0 : len;
|
|
}), ({
|
|
sum = csum_and_memcpy(base, addr + off, len, sum, off);
|
|
})
|
|
)
|
|
csstate->csum = csum_shift(sum, csstate->off);
|
|
csstate->off += bytes;
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL(csum_and_copy_to_iter);
|
|
|
|
size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
|
|
struct iov_iter *i)
|
|
{
|
|
#ifdef CONFIG_CRYPTO_HASH
|
|
struct ahash_request *hash = hashp;
|
|
struct scatterlist sg;
|
|
size_t copied;
|
|
|
|
copied = copy_to_iter(addr, bytes, i);
|
|
sg_init_one(&sg, addr, copied);
|
|
ahash_request_set_crypt(hash, &sg, NULL, copied);
|
|
crypto_ahash_update(hash);
|
|
return copied;
|
|
#else
|
|
return 0;
|
|
#endif
|
|
}
|
|
EXPORT_SYMBOL(hash_and_copy_to_iter);
|
|
|
|
static int iov_npages(const struct iov_iter *i, int maxpages)
|
|
{
|
|
size_t skip = i->iov_offset, size = i->count;
|
|
const struct iovec *p;
|
|
int npages = 0;
|
|
|
|
for (p = i->iov; size; skip = 0, p++) {
|
|
unsigned offs = offset_in_page(p->iov_base + skip);
|
|
size_t len = min(p->iov_len - skip, size);
|
|
|
|
if (len) {
|
|
size -= len;
|
|
npages += DIV_ROUND_UP(offs + len, PAGE_SIZE);
|
|
if (unlikely(npages > maxpages))
|
|
return maxpages;
|
|
}
|
|
}
|
|
return npages;
|
|
}
|
|
|
|
static int bvec_npages(const struct iov_iter *i, int maxpages)
|
|
{
|
|
size_t skip = i->iov_offset, size = i->count;
|
|
const struct bio_vec *p;
|
|
int npages = 0;
|
|
|
|
for (p = i->bvec; size; skip = 0, p++) {
|
|
unsigned offs = (p->bv_offset + skip) % PAGE_SIZE;
|
|
size_t len = min(p->bv_len - skip, size);
|
|
|
|
size -= len;
|
|
npages += DIV_ROUND_UP(offs + len, PAGE_SIZE);
|
|
if (unlikely(npages > maxpages))
|
|
return maxpages;
|
|
}
|
|
return npages;
|
|
}
|
|
|
|
int iov_iter_npages(const struct iov_iter *i, int maxpages)
|
|
{
|
|
if (unlikely(!i->count))
|
|
return 0;
|
|
/* iovec and kvec have identical layouts */
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
|
|
return iov_npages(i, maxpages);
|
|
if (iov_iter_is_bvec(i))
|
|
return bvec_npages(i, maxpages);
|
|
if (iov_iter_is_pipe(i)) {
|
|
unsigned int iter_head;
|
|
int npages;
|
|
size_t off;
|
|
|
|
if (!sanity(i))
|
|
return 0;
|
|
|
|
data_start(i, &iter_head, &off);
|
|
/* some of this one + all after this one */
|
|
npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
|
|
return min(npages, maxpages);
|
|
}
|
|
if (iov_iter_is_xarray(i)) {
|
|
unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE;
|
|
int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE);
|
|
return min(npages, maxpages);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_npages);
|
|
|
|
const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
|
|
{
|
|
*new = *old;
|
|
if (unlikely(iov_iter_is_pipe(new))) {
|
|
WARN_ON(1);
|
|
return NULL;
|
|
}
|
|
if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new)))
|
|
return NULL;
|
|
if (iov_iter_is_bvec(new))
|
|
return new->bvec = kmemdup(new->bvec,
|
|
new->nr_segs * sizeof(struct bio_vec),
|
|
flags);
|
|
else
|
|
/* iovec and kvec have identical layout */
|
|
return new->iov = kmemdup(new->iov,
|
|
new->nr_segs * sizeof(struct iovec),
|
|
flags);
|
|
}
|
|
EXPORT_SYMBOL(dup_iter);
|
|
|
|
static int copy_compat_iovec_from_user(struct iovec *iov,
|
|
const struct iovec __user *uvec, unsigned long nr_segs)
|
|
{
|
|
const struct compat_iovec __user *uiov =
|
|
(const struct compat_iovec __user *)uvec;
|
|
int ret = -EFAULT, i;
|
|
|
|
if (!user_access_begin(uiov, nr_segs * sizeof(*uiov)))
|
|
return -EFAULT;
|
|
|
|
for (i = 0; i < nr_segs; i++) {
|
|
compat_uptr_t buf;
|
|
compat_ssize_t len;
|
|
|
|
unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
|
|
unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end);
|
|
|
|
/* check for compat_size_t not fitting in compat_ssize_t .. */
|
|
if (len < 0) {
|
|
ret = -EINVAL;
|
|
goto uaccess_end;
|
|
}
|
|
iov[i].iov_base = compat_ptr(buf);
|
|
iov[i].iov_len = len;
|
|
}
|
|
|
|
ret = 0;
|
|
uaccess_end:
|
|
user_access_end();
|
|
return ret;
|
|
}
|
|
|
|
static int copy_iovec_from_user(struct iovec *iov,
|
|
const struct iovec __user *uvec, unsigned long nr_segs)
|
|
{
|
|
unsigned long seg;
|
|
|
|
if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec)))
|
|
return -EFAULT;
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
|
if ((ssize_t)iov[seg].iov_len < 0)
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct iovec *iovec_from_user(const struct iovec __user *uvec,
|
|
unsigned long nr_segs, unsigned long fast_segs,
|
|
struct iovec *fast_iov, bool compat)
|
|
{
|
|
struct iovec *iov = fast_iov;
|
|
int ret;
|
|
|
|
/*
|
|
* SuS says "The readv() function *may* fail if the iovcnt argument was
|
|
* less than or equal to 0, or greater than {IOV_MAX}. Linux has
|
|
* traditionally returned zero for zero segments, so...
|
|
*/
|
|
if (nr_segs == 0)
|
|
return iov;
|
|
if (nr_segs > UIO_MAXIOV)
|
|
return ERR_PTR(-EINVAL);
|
|
if (nr_segs > fast_segs) {
|
|
iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
|
|
if (!iov)
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
if (compat)
|
|
ret = copy_compat_iovec_from_user(iov, uvec, nr_segs);
|
|
else
|
|
ret = copy_iovec_from_user(iov, uvec, nr_segs);
|
|
if (ret) {
|
|
if (iov != fast_iov)
|
|
kfree(iov);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
return iov;
|
|
}
|
|
|
|
ssize_t __import_iovec(int type, const struct iovec __user *uvec,
|
|
unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
|
|
struct iov_iter *i, bool compat)
|
|
{
|
|
ssize_t total_len = 0;
|
|
unsigned long seg;
|
|
struct iovec *iov;
|
|
|
|
iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat);
|
|
if (IS_ERR(iov)) {
|
|
*iovp = NULL;
|
|
return PTR_ERR(iov);
|
|
}
|
|
|
|
/*
|
|
* According to the Single Unix Specification we should return EINVAL if
|
|
* an element length is < 0 when cast to ssize_t or if the total length
|
|
* would overflow the ssize_t return value of the system call.
|
|
*
|
|
* Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
|
|
* overflow case.
|
|
*/
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
|
ssize_t len = (ssize_t)iov[seg].iov_len;
|
|
|
|
if (!access_ok(iov[seg].iov_base, len)) {
|
|
if (iov != *iovp)
|
|
kfree(iov);
|
|
*iovp = NULL;
|
|
return -EFAULT;
|
|
}
|
|
|
|
if (len > MAX_RW_COUNT - total_len) {
|
|
len = MAX_RW_COUNT - total_len;
|
|
iov[seg].iov_len = len;
|
|
}
|
|
total_len += len;
|
|
}
|
|
|
|
iov_iter_init(i, type, iov, nr_segs, total_len);
|
|
if (iov == *iovp)
|
|
*iovp = NULL;
|
|
else
|
|
*iovp = iov;
|
|
return total_len;
|
|
}
|
|
|
|
/**
|
|
* import_iovec() - Copy an array of &struct iovec from userspace
|
|
* into the kernel, check that it is valid, and initialize a new
|
|
* &struct iov_iter iterator to access it.
|
|
*
|
|
* @type: One of %READ or %WRITE.
|
|
* @uvec: Pointer to the userspace array.
|
|
* @nr_segs: Number of elements in userspace array.
|
|
* @fast_segs: Number of elements in @iov.
|
|
* @iovp: (input and output parameter) Pointer to pointer to (usually small
|
|
* on-stack) kernel array.
|
|
* @i: Pointer to iterator that will be initialized on success.
|
|
*
|
|
* If the array pointed to by *@iov is large enough to hold all @nr_segs,
|
|
* then this function places %NULL in *@iov on return. Otherwise, a new
|
|
* array will be allocated and the result placed in *@iov. This means that
|
|
* the caller may call kfree() on *@iov regardless of whether the small
|
|
* on-stack array was used or not (and regardless of whether this function
|
|
* returns an error or not).
|
|
*
|
|
* Return: Negative error code on error, bytes imported on success
|
|
*/
|
|
ssize_t import_iovec(int type, const struct iovec __user *uvec,
|
|
unsigned nr_segs, unsigned fast_segs,
|
|
struct iovec **iovp, struct iov_iter *i)
|
|
{
|
|
return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i,
|
|
in_compat_syscall());
|
|
}
|
|
EXPORT_SYMBOL(import_iovec);
|
|
|
|
int import_single_range(int rw, void __user *buf, size_t len,
|
|
struct iovec *iov, struct iov_iter *i)
|
|
{
|
|
if (len > MAX_RW_COUNT)
|
|
len = MAX_RW_COUNT;
|
|
if (unlikely(!access_ok(buf, len)))
|
|
return -EFAULT;
|
|
|
|
iov->iov_base = buf;
|
|
iov->iov_len = len;
|
|
iov_iter_init(i, rw, iov, 1, len);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(import_single_range);
|
|
|
|
/**
|
|
* iov_iter_restore() - Restore a &struct iov_iter to the same state as when
|
|
* iov_iter_save_state() was called.
|
|
*
|
|
* @i: &struct iov_iter to restore
|
|
* @state: state to restore from
|
|
*
|
|
* Used after iov_iter_save_state() to bring restore @i, if operations may
|
|
* have advanced it.
|
|
*
|
|
* Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC
|
|
*/
|
|
void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
|
|
{
|
|
if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) &&
|
|
!iov_iter_is_kvec(i))
|
|
return;
|
|
i->iov_offset = state->iov_offset;
|
|
i->count = state->count;
|
|
/*
|
|
* For the *vec iters, nr_segs + iov is constant - if we increment
|
|
* the vec, then we also decrement the nr_segs count. Hence we don't
|
|
* need to track both of these, just one is enough and we can deduct
|
|
* the other from that. ITER_KVEC and ITER_IOVEC are the same struct
|
|
* size, so we can just increment the iov pointer as they are unionzed.
|
|
* ITER_BVEC _may_ be the same size on some archs, but on others it is
|
|
* not. Be safe and handle it separately.
|
|
*/
|
|
BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
|
|
if (iov_iter_is_bvec(i))
|
|
i->bvec -= state->nr_segs - i->nr_segs;
|
|
else
|
|
i->iov -= state->nr_segs - i->nr_segs;
|
|
i->nr_segs = state->nr_segs;
|
|
}
|