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mm/iov_iter.c
17.2 KB
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#include <linux/export.h> #include <linux/uio.h> #include <linux/pagemap.h> |
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#include <linux/slab.h> #include <linux/vmalloc.h> |
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#include <net/checksum.h> |
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#define iterate_iovec(i, n, __v, __p, skip, STEP) { \ size_t left; \ size_t wanted = n; \ __p = i->iov; \ __v.iov_len = min(n, __p->iov_len - skip); \ if (likely(__v.iov_len)) { \ __v.iov_base = __p->iov_base + skip; \ left = (STEP); \ __v.iov_len -= left; \ skip += __v.iov_len; \ n -= __v.iov_len; \ } else { \ left = 0; \ } \ while (unlikely(!left && n)) { \ __p++; \ __v.iov_len = min(n, __p->iov_len); \ if (unlikely(!__v.iov_len)) \ continue; \ __v.iov_base = __p->iov_base; \ left = (STEP); \ __v.iov_len -= left; \ skip = __v.iov_len; \ n -= __v.iov_len; \ } \ n = wanted - n; \ } |
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#define iterate_kvec(i, n, __v, __p, skip, STEP) { \ size_t wanted = n; \ __p = i->kvec; \ __v.iov_len = min(n, __p->iov_len - skip); \ if (likely(__v.iov_len)) { \ __v.iov_base = __p->iov_base + skip; \ (void)(STEP); \ skip += __v.iov_len; \ n -= __v.iov_len; \ } \ while (unlikely(n)) { \ __p++; \ __v.iov_len = min(n, __p->iov_len); \ if (unlikely(!__v.iov_len)) \ continue; \ __v.iov_base = __p->iov_base; \ (void)(STEP); \ skip = __v.iov_len; \ n -= __v.iov_len; \ } \ n = wanted; \ } |
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#define iterate_bvec(i, n, __v, __p, skip, STEP) { \ size_t wanted = n; \ __p = i->bvec; \ __v.bv_len = min_t(size_t, n, __p->bv_len - skip); \ if (likely(__v.bv_len)) { \ __v.bv_page = __p->bv_page; \ __v.bv_offset = __p->bv_offset + skip; \ (void)(STEP); \ skip += __v.bv_len; \ n -= __v.bv_len; \ } \ while (unlikely(n)) { \ __p++; \ __v.bv_len = min_t(size_t, n, __p->bv_len); \ if (unlikely(!__v.bv_len)) \ continue; \ __v.bv_page = __p->bv_page; \ __v.bv_offset = __p->bv_offset; \ (void)(STEP); \ skip = __v.bv_len; \ n -= __v.bv_len; \ } \ n = wanted; \ } |
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#define iterate_all_kinds(i, n, v, I, B, K) { \ |
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size_t skip = i->iov_offset; \ if (unlikely(i->type & ITER_BVEC)) { \ const struct bio_vec *bvec; \ struct bio_vec v; \ iterate_bvec(i, n, v, bvec, skip, (B)) \ |
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} else if (unlikely(i->type & ITER_KVEC)) { \ const struct kvec *kvec; \ struct kvec v; \ iterate_kvec(i, n, v, kvec, skip, (K)) \ |
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} else { \ const struct iovec *iov; \ struct iovec v; \ iterate_iovec(i, n, v, iov, skip, (I)) \ } \ } |
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#define iterate_and_advance(i, n, v, I, B, K) { \ |
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size_t skip = i->iov_offset; \ if (unlikely(i->type & ITER_BVEC)) { \ const struct bio_vec *bvec; \ struct bio_vec v; \ iterate_bvec(i, n, v, bvec, skip, (B)) \ if (skip == bvec->bv_len) { \ bvec++; \ skip = 0; \ } \ i->nr_segs -= bvec - i->bvec; \ i->bvec = bvec; \ |
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} else if (unlikely(i->type & ITER_KVEC)) { \ const struct kvec *kvec; \ struct kvec v; \ iterate_kvec(i, n, v, kvec, skip, (K)) \ if (skip == kvec->iov_len) { \ kvec++; \ skip = 0; \ } \ i->nr_segs -= kvec - i->kvec; \ i->kvec = kvec; \ |
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} else { \ const struct iovec *iov; \ struct iovec v; \ iterate_iovec(i, n, v, iov, skip, (I)) \ if (skip == iov->iov_len) { \ iov++; \ skip = 0; \ } \ i->nr_segs -= iov - i->iov; \ i->iov = iov; \ } \ i->count -= n; \ i->iov_offset = skip; \ } |
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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) { size_t skip, copy, left, wanted; const struct iovec *iov; char __user *buf; void *kaddr, *from; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; wanted = bytes; iov = i->iov; skip = i->iov_offset; buf = iov->iov_base + skip; copy = min(bytes, iov->iov_len - skip); if (!fault_in_pages_writeable(buf, copy)) { kaddr = kmap_atomic(page); from = kaddr + offset; /* first chunk, usually the only one */ left = __copy_to_user_inatomic(buf, from, copy); copy -= left; skip += copy; from += copy; bytes -= copy; while (unlikely(!left && bytes)) { iov++; buf = iov->iov_base; copy = min(bytes, iov->iov_len); left = __copy_to_user_inatomic(buf, from, copy); copy -= left; skip = copy; from += copy; bytes -= copy; } if (likely(!bytes)) { kunmap_atomic(kaddr); goto done; } offset = from - kaddr; buf += copy; kunmap_atomic(kaddr); copy = min(bytes, iov->iov_len - skip); } /* Too bad - revert to non-atomic kmap */ kaddr = kmap(page); from = kaddr + offset; left = __copy_to_user(buf, from, copy); copy -= left; skip += copy; from += copy; bytes -= copy; while (unlikely(!left && bytes)) { iov++; buf = iov->iov_base; copy = min(bytes, iov->iov_len); left = __copy_to_user(buf, from, copy); copy -= left; skip = copy; from += copy; bytes -= copy; } kunmap(page); done: |
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if (skip == iov->iov_len) { iov++; skip = 0; } |
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i->count -= wanted - bytes; i->nr_segs -= iov - i->iov; i->iov = iov; i->iov_offset = skip; return wanted - bytes; } |
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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) { size_t skip, copy, left, wanted; const struct iovec *iov; char __user *buf; void *kaddr, *to; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; wanted = bytes; iov = i->iov; skip = i->iov_offset; buf = iov->iov_base + skip; copy = min(bytes, iov->iov_len - skip); if (!fault_in_pages_readable(buf, copy)) { kaddr = kmap_atomic(page); to = kaddr + offset; /* first chunk, usually the only one */ left = __copy_from_user_inatomic(to, buf, copy); copy -= left; skip += copy; to += copy; bytes -= copy; while (unlikely(!left && bytes)) { iov++; buf = iov->iov_base; copy = min(bytes, iov->iov_len); left = __copy_from_user_inatomic(to, buf, copy); copy -= left; skip = copy; to += copy; bytes -= copy; } if (likely(!bytes)) { kunmap_atomic(kaddr); goto done; } offset = to - kaddr; buf += copy; kunmap_atomic(kaddr); copy = min(bytes, iov->iov_len - skip); } /* Too bad - revert to non-atomic kmap */ kaddr = kmap(page); to = kaddr + offset; left = __copy_from_user(to, buf, copy); copy -= left; skip += copy; to += copy; bytes -= copy; while (unlikely(!left && bytes)) { iov++; buf = iov->iov_base; copy = min(bytes, iov->iov_len); left = __copy_from_user(to, buf, copy); copy -= left; skip = copy; to += copy; bytes -= copy; } kunmap(page); done: |
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if (skip == iov->iov_len) { iov++; skip = 0; } |
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i->count -= wanted - bytes; i->nr_segs -= iov - i->iov; i->iov = iov; i->iov_offset = skip; return wanted - bytes; } |
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/* * Fault in the first iovec of the given iov_iter, to a maximum length * of bytes. Returns 0 on success, or non-zero if the memory could not be * accessed (ie. because it is an invalid address). * * writev-intensive code may want this to prefault several iovecs -- that * would be possible (callers must not rely on the fact that _only_ the * first iovec will be faulted with the current implementation). */ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) { |
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if (!(i->type & (ITER_BVEC|ITER_KVEC))) { |
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char __user *buf = i->iov->iov_base + i->iov_offset; bytes = min(bytes, i->iov->iov_len - i->iov_offset); return fault_in_pages_readable(buf, bytes); } return 0; |
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} EXPORT_SYMBOL(iov_iter_fault_in_readable); |
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void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, unsigned long nr_segs, size_t count) { /* It will get better. Eventually... */ |
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if (segment_eq(get_fs(), KERNEL_DS)) { |
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direction |= ITER_KVEC; |
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i->type = direction; i->kvec = (struct kvec *)iov; } else { i->type = direction; i->iov = iov; } |
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i->nr_segs = nr_segs; i->iov_offset = 0; i->count = count; } EXPORT_SYMBOL(iov_iter_init); |
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static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len) { char *from = kmap_atomic(page); memcpy(to, from + offset, len); kunmap_atomic(from); } static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t len) { char *to = kmap_atomic(page); memcpy(to + offset, from, len); kunmap_atomic(to); } |
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static void memzero_page(struct page *page, size_t offset, size_t len) { char *addr = kmap_atomic(page); memset(addr + offset, 0, len); kunmap_atomic(addr); } |
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size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i) |
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{ |
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char *from = addr; |
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if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; |
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iterate_and_advance(i, bytes, v, __copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len), memcpy_to_page(v.bv_page, v.bv_offset, |
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(from += v.bv_len) - v.bv_len, v.bv_len), memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len) |
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) |
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return bytes; |
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} |
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EXPORT_SYMBOL(copy_to_iter); |
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size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) |
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{ |
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char *to = addr; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; iterate_and_advance(i, bytes, v, __copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, |
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v.bv_offset, v.bv_len), memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len) |
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) return bytes; |
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} |
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EXPORT_SYMBOL(copy_from_iter); |
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size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) { char *to = addr; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; iterate_and_advance(i, bytes, v, __copy_from_user_nocache((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, v.bv_offset, v.bv_len), memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len) ) return bytes; } EXPORT_SYMBOL(copy_from_iter_nocache); |
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size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i) { |
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if (i->type & (ITER_BVEC|ITER_KVEC)) { void *kaddr = kmap_atomic(page); size_t wanted = copy_to_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); return wanted; } else |
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return copy_page_to_iter_iovec(page, offset, bytes, i); } 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) { |
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if (i->type & (ITER_BVEC|ITER_KVEC)) { |
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void *kaddr = kmap_atomic(page); size_t wanted = copy_from_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); return wanted; } else |
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return copy_page_from_iter_iovec(page, offset, bytes, i); } EXPORT_SYMBOL(copy_page_from_iter); |
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size_t iov_iter_zero(size_t bytes, struct iov_iter *i) { |
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if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; iterate_and_advance(i, bytes, v, __clear_user(v.iov_base, v.iov_len), |
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memzero_page(v.bv_page, v.bv_offset, v.bv_len), memset(v.iov_base, 0, v.iov_len) |
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) return bytes; |
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} EXPORT_SYMBOL(iov_iter_zero); |
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size_t iov_iter_copy_from_user_atomic(struct page *page, struct iov_iter *i, unsigned long offset, size_t bytes) { |
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char *kaddr = kmap_atomic(page), *p = kaddr + offset; iterate_all_kinds(i, bytes, v, __copy_from_user_inatomic((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page, |
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v.bv_offset, v.bv_len), memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len) |
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) kunmap_atomic(kaddr); return bytes; |
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} EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); void iov_iter_advance(struct iov_iter *i, size_t size) { |
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iterate_and_advance(i, size, v, 0, 0, 0) |
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} EXPORT_SYMBOL(iov_iter_advance); /* * 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) return i->count; else if (i->type & ITER_BVEC) |
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return min(i->count, i->bvec->bv_len - i->iov_offset); |
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else return min(i->count, i->iov->iov_len - i->iov_offset); |
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} EXPORT_SYMBOL(iov_iter_single_seg_count); |
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void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *iov, unsigned long nr_segs, size_t count) { BUG_ON(!(direction & ITER_KVEC)); i->type = direction; i->kvec = (struct kvec *)iov; i->nr_segs = nr_segs; i->iov_offset = 0; i->count = count; } EXPORT_SYMBOL(iov_iter_kvec); |
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unsigned long iov_iter_alignment(const struct iov_iter *i) { |
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unsigned long res = 0; size_t size = i->count; if (!size) return 0; iterate_all_kinds(i, size, v, (res |= (unsigned long)v.iov_base | v.iov_len, 0), |
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res |= v.bv_offset | v.bv_len, res |= (unsigned long)v.iov_base | v.iov_len |
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) return res; |
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} EXPORT_SYMBOL(iov_iter_alignment); ssize_t iov_iter_get_pages(struct iov_iter *i, |
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struct page **pages, size_t maxsize, unsigned maxpages, |
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size_t *start) { |
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if (maxsize > i->count) maxsize = i->count; if (!maxsize) return 0; iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); int n; int res; if (len > maxpages * PAGE_SIZE) len = maxpages * PAGE_SIZE; addr &= ~(PAGE_SIZE - 1); n = DIV_ROUND_UP(len, PAGE_SIZE); res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages); if (unlikely(res < 0)) return res; return (res == n ? len : res * PAGE_SIZE) - *start; 0;}),({ /* can't be more than PAGE_SIZE */ *start = v.bv_offset; get_page(*pages = v.bv_page); return v.bv_len; |
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}),({ return -EFAULT; |
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}) ) return 0; |
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} EXPORT_SYMBOL(iov_iter_get_pages); |
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static struct page **get_pages_array(size_t n) { struct page **p = kmalloc(n * sizeof(struct page *), GFP_KERNEL); if (!p) p = vmalloc(n * sizeof(struct page *)); return p; } |
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ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages, size_t maxsize, size_t *start) { |
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struct page **p; if (maxsize > i->count) maxsize = i->count; if (!maxsize) return 0; iterate_all_kinds(i, maxsize, v, ({ unsigned long addr = (unsigned long)v.iov_base; size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1)); int n; int res; addr &= ~(PAGE_SIZE - 1); n = DIV_ROUND_UP(len, PAGE_SIZE); p = get_pages_array(n); if (!p) return -ENOMEM; res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p); if (unlikely(res < 0)) { kvfree(p); return res; } *pages = p; return (res == n ? len : res * PAGE_SIZE) - *start; 0;}),({ /* can't be more than PAGE_SIZE */ *start = v.bv_offset; *pages = p = get_pages_array(1); if (!p) return -ENOMEM; get_page(*p = v.bv_page); return v.bv_len; |
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}),({ return -EFAULT; |
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}) ) return 0; |
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} EXPORT_SYMBOL(iov_iter_get_pages_alloc); |
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size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i) { char *to = addr; __wsum sum, next; size_t off = 0; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; sum = *csum; iterate_and_advance(i, bytes, v, ({ int err = 0; next = csum_and_copy_from_user(v.iov_base, (to += v.iov_len) - v.iov_len, v.iov_len, 0, &err); if (!err) { sum = csum_block_add(sum, next, off); off += v.iov_len; } err ? v.iov_len : 0; }), ({ char *p = kmap_atomic(v.bv_page); next = csum_partial_copy_nocheck(p + v.bv_offset, (to += v.bv_len) - v.bv_len, v.bv_len, 0); kunmap_atomic(p); sum = csum_block_add(sum, next, off); off += v.bv_len; }),({ next = csum_partial_copy_nocheck(v.iov_base, (to += v.iov_len) - v.iov_len, v.iov_len, 0); sum = csum_block_add(sum, next, off); off += v.iov_len; }) ) *csum = sum; return bytes; } EXPORT_SYMBOL(csum_and_copy_from_iter); size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i) { char *from = addr; __wsum sum, next; size_t off = 0; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; sum = *csum; iterate_and_advance(i, bytes, v, ({ int err = 0; next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len, v.iov_base, v.iov_len, 0, &err); if (!err) { sum = csum_block_add(sum, next, off); off += v.iov_len; } err ? v.iov_len : 0; }), ({ char *p = kmap_atomic(v.bv_page); next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len, p + v.bv_offset, v.bv_len, 0); kunmap_atomic(p); sum = csum_block_add(sum, next, off); off += v.bv_len; }),({ next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len, v.iov_base, v.iov_len, 0); sum = csum_block_add(sum, next, off); off += v.iov_len; }) ) *csum = sum; return bytes; } EXPORT_SYMBOL(csum_and_copy_to_iter); |
62a8067a7
|
694 695 |
int iov_iter_npages(const struct iov_iter *i, int maxpages) { |
e0f2dc406
|
696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 |
size_t size = i->count; int npages = 0; if (!size) return 0; iterate_all_kinds(i, size, v, ({ unsigned long p = (unsigned long)v.iov_base; npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE) - p / PAGE_SIZE; if (npages >= maxpages) return maxpages; 0;}),({ npages++; if (npages >= maxpages) return maxpages; |
a280455fa
|
712 713 714 715 716 717 |
}),({ unsigned long p = (unsigned long)v.iov_base; npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE) - p / PAGE_SIZE; if (npages >= maxpages) return maxpages; |
e0f2dc406
|
718 719 720 |
}) ) return npages; |
62a8067a7
|
721 |
} |
f67da30c1
|
722 |
EXPORT_SYMBOL(iov_iter_npages); |