iov_iter.c revision f0d1bec9d58d4c038d0ac958c9af82be6eb18045
14f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/export.h> 24f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/uio.h> 34f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/pagemap.h> 491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro#include <linux/slab.h> 591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro#include <linux/vmalloc.h> 64f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 74f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 84f18cd317a118c28482f97303600a2fe2ada6c79Al Viro struct iov_iter *i) 94f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 104f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t skip, copy, left, wanted; 114f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov; 124f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf; 134f18cd317a118c28482f97303600a2fe2ada6c79Al Viro void *kaddr, *from; 144f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 154f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(bytes > i->count)) 164f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes = i->count; 174f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 184f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(!bytes)) 194f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return 0; 204f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 214f18cd317a118c28482f97303600a2fe2ada6c79Al Viro wanted = bytes; 224f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov = i->iov; 234f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = i->iov_offset; 244f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base + skip; 254f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - skip); 264f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 274f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (!fault_in_pages_writeable(buf, copy)) { 284f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap_atomic(page); 294f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from = kaddr + offset; 304f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 314f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* first chunk, usually the only one */ 324f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user_inatomic(buf, from, copy); 334f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 344f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip += copy; 354f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 364f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 374f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 384f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (unlikely(!left && bytes)) { 394f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 404f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base; 414f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len); 424f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user_inatomic(buf, from, copy); 434f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 444f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = copy; 454f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 464f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 474f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 484f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(!bytes)) { 494f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 504f18cd317a118c28482f97303600a2fe2ada6c79Al Viro goto done; 514f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 524f18cd317a118c28482f97303600a2fe2ada6c79Al Viro offset = from - kaddr; 534f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf += copy; 544f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 554f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - skip); 564f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 574f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* Too bad - revert to non-atomic kmap */ 584f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap(page); 594f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from = kaddr + offset; 604f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user(buf, from, copy); 614f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 624f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip += copy; 634f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 644f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 654f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (unlikely(!left && bytes)) { 664f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 674f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base; 684f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len); 694f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user(buf, from, copy); 704f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 714f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = copy; 724f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 734f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 744f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 754f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap(page); 764f18cd317a118c28482f97303600a2fe2ada6c79Al Virodone: 774f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= wanted - bytes; 784f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->nr_segs -= iov - i->iov; 794f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov = iov; 804f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset = skip; 814f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return wanted - bytes; 824f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 834f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(copy_page_to_iter); 844f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 85f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Virosize_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 86f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro struct iov_iter *i) 87f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro{ 88f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro size_t skip, copy, left, wanted; 89f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro const struct iovec *iov; 90f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro char __user *buf; 91f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro void *kaddr, *to; 92f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro 93f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro if (unlikely(bytes > i->count)) 94f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro bytes = i->count; 95f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro 96f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro if (unlikely(!bytes)) 97f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro return 0; 98f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro 99f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro wanted = bytes; 100f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro iov = i->iov; 101f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro skip = i->iov_offset; 102f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro buf = iov->iov_base + skip; 103f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy = min(bytes, iov->iov_len - skip); 104f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro 105f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro if (!fault_in_pages_readable(buf, copy)) { 106f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro kaddr = kmap_atomic(page); 107f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro to = kaddr + offset; 108f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro 109f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro /* first chunk, usually the only one */ 110f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro left = __copy_from_user_inatomic(to, buf, copy); 111f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy -= left; 112f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro skip += copy; 113f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro to += copy; 114f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro bytes -= copy; 115f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro 116f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro while (unlikely(!left && bytes)) { 117f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro iov++; 118f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro buf = iov->iov_base; 119f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy = min(bytes, iov->iov_len); 120f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro left = __copy_from_user_inatomic(to, buf, copy); 121f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy -= left; 122f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro skip = copy; 123f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro to += copy; 124f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro bytes -= copy; 125f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro } 126f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro if (likely(!bytes)) { 127f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro kunmap_atomic(kaddr); 128f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro goto done; 129f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro } 130f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro offset = to - kaddr; 131f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro buf += copy; 132f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro kunmap_atomic(kaddr); 133f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy = min(bytes, iov->iov_len - skip); 134f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro } 135f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro /* Too bad - revert to non-atomic kmap */ 136f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro kaddr = kmap(page); 137f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro to = kaddr + offset; 138f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro left = __copy_from_user(to, buf, copy); 139f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy -= left; 140f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro skip += copy; 141f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro to += copy; 142f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro bytes -= copy; 143f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro while (unlikely(!left && bytes)) { 144f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro iov++; 145f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro buf = iov->iov_base; 146f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy = min(bytes, iov->iov_len); 147f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro left = __copy_from_user(to, buf, copy); 148f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro copy -= left; 149f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro skip = copy; 150f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro to += copy; 151f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro bytes -= copy; 152f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro } 153f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro kunmap(page); 154f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Virodone: 155f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro i->count -= wanted - bytes; 156f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro i->nr_segs -= iov - i->iov; 157f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro i->iov = iov; 158f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro i->iov_offset = skip; 159f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro return wanted - bytes; 160f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro} 161f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al ViroEXPORT_SYMBOL(copy_page_from_iter); 162f0d1bec9d58d4c038d0ac958c9af82be6eb18045Al Viro 1634f18cd317a118c28482f97303600a2fe2ada6c79Al Virostatic size_t __iovec_copy_from_user_inatomic(char *vaddr, 1644f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov, size_t base, size_t bytes) 1654f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1664f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t copied = 0, left = 0; 1674f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1684f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (bytes) { 1694f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = iov->iov_base + base; 1704f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int copy = min(bytes, iov->iov_len - base); 1714f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1724f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base = 0; 1734f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_from_user_inatomic(vaddr, buf, copy); 1744f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied += copy; 1754f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 1764f18cd317a118c28482f97303600a2fe2ada6c79Al Viro vaddr += copy; 1774f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 1784f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1794f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(left)) 1804f18cd317a118c28482f97303600a2fe2ada6c79Al Viro break; 1814f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1824f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return copied - left; 1834f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1844f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1854f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 1864f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Copy as much as we can into the page and return the number of bytes which 1874f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * were successfully copied. If a fault is encountered then return the number of 1884f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * bytes which were copied. 1894f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1904f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t iov_iter_copy_from_user_atomic(struct page *page, 1914f18cd317a118c28482f97303600a2fe2ada6c79Al Viro struct iov_iter *i, unsigned long offset, size_t bytes) 1924f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1934f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char *kaddr; 1944f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t copied; 1954f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1964f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap_atomic(page); 1974f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(i->nr_segs == 1)) { 1984f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int left; 1994f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = i->iov->iov_base + i->iov_offset; 2004f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); 2014f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied = bytes - left; 2024f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } else { 2034f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied = __iovec_copy_from_user_inatomic(kaddr + offset, 2044f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov, i->iov_offset, bytes); 2054f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 2064f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 2074f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 2084f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return copied; 2094f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 2104f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_copy_from_user_atomic); 2114f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 2124f18cd317a118c28482f97303600a2fe2ada6c79Al Virovoid iov_iter_advance(struct iov_iter *i, size_t bytes) 2134f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 2144f18cd317a118c28482f97303600a2fe2ada6c79Al Viro BUG_ON(i->count < bytes); 2154f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 2164f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(i->nr_segs == 1)) { 2174f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset += bytes; 2184f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= bytes; 2194f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } else { 2204f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov = i->iov; 2214f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t base = i->iov_offset; 2224f18cd317a118c28482f97303600a2fe2ada6c79Al Viro unsigned long nr_segs = i->nr_segs; 2234f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 2244f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* 2254f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * The !iov->iov_len check ensures we skip over unlikely 2264f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * zero-length segments (without overruning the iovec). 2274f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 2284f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (bytes || unlikely(i->count && !iov->iov_len)) { 2294f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int copy; 2304f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 2314f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - base); 2324f18cd317a118c28482f97303600a2fe2ada6c79Al Viro BUG_ON(!i->count || i->count < copy); 2334f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= copy; 2344f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 2354f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base += copy; 2364f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (iov->iov_len == base) { 2374f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 2384f18cd317a118c28482f97303600a2fe2ada6c79Al Viro nr_segs--; 2394f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base = 0; 2404f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 2414f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 2424f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov = iov; 2434f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset = base; 2444f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->nr_segs = nr_segs; 2454f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 2464f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 2474f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_advance); 2484f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 2494f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 2504f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Fault in the first iovec of the given iov_iter, to a maximum length 2514f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * of bytes. Returns 0 on success, or non-zero if the memory could not be 2524f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * accessed (ie. because it is an invalid address). 2534f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * 2544f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * writev-intensive code may want this to prefault several iovecs -- that 2554f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * would be possible (callers must not rely on the fact that _only_ the 2564f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * first iovec will be faulted with the current implementation). 2574f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 2584f18cd317a118c28482f97303600a2fe2ada6c79Al Viroint iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) 2594f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 2604f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = i->iov->iov_base + i->iov_offset; 2614f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes = min(bytes, i->iov->iov_len - i->iov_offset); 2624f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return fault_in_pages_readable(buf, bytes); 2634f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 2644f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_fault_in_readable); 2654f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 2664f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 2674f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Return the count of just the current iov_iter segment. 2684f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 2694f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t iov_iter_single_seg_count(const struct iov_iter *i) 2704f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 2714f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov = i->iov; 2724f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (i->nr_segs == 1) 2734f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return i->count; 2744f18cd317a118c28482f97303600a2fe2ada6c79Al Viro else 2754f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return min(i->count, iov->iov_len - i->iov_offset); 2764f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 2774f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_single_seg_count); 278886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 279886a39115005ced8b15ab067c9c2a8d546b40a5eAl Virounsigned long iov_iter_alignment(const struct iov_iter *i) 280886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro{ 281886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro const struct iovec *iov = i->iov; 282886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro unsigned long res; 283886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size_t size = i->count; 284886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size_t n; 285886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 286886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro if (!size) 287886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return 0; 288886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 289886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res = (unsigned long)iov->iov_base + i->iov_offset; 290886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro n = iov->iov_len - i->iov_offset; 291886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro if (n >= size) 292886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return res | size; 293886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size -= n; 294886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= n; 295886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro while (size > (++iov)->iov_len) { 296886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= (unsigned long)iov->iov_base | iov->iov_len; 297886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size -= iov->iov_len; 298886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro } 299886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= (unsigned long)iov->iov_base | size; 300886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return res; 301886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro} 302886a39115005ced8b15ab067c9c2a8d546b40a5eAl ViroEXPORT_SYMBOL(iov_iter_alignment); 30371d8e532b1549a478e6a6a8a44f309d050294d00Al Viro 30471d8e532b1549a478e6a6a8a44f309d050294d00Al Virovoid iov_iter_init(struct iov_iter *i, int direction, 30571d8e532b1549a478e6a6a8a44f309d050294d00Al Viro const struct iovec *iov, unsigned long nr_segs, 30671d8e532b1549a478e6a6a8a44f309d050294d00Al Viro size_t count) 30771d8e532b1549a478e6a6a8a44f309d050294d00Al Viro{ 30871d8e532b1549a478e6a6a8a44f309d050294d00Al Viro /* It will get better. Eventually... */ 30971d8e532b1549a478e6a6a8a44f309d050294d00Al Viro if (segment_eq(get_fs(), KERNEL_DS)) 31071d8e532b1549a478e6a6a8a44f309d050294d00Al Viro direction |= REQ_KERNEL; 31171d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->type = direction; 31271d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->iov = iov; 31371d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->nr_segs = nr_segs; 31471d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->iov_offset = 0; 31571d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->count = count; 31671d8e532b1549a478e6a6a8a44f309d050294d00Al Viro} 31771d8e532b1549a478e6a6a8a44f309d050294d00Al ViroEXPORT_SYMBOL(iov_iter_init); 3187b2c99d15559e285384c742db52316802e24b0bdAl Viro 3197b2c99d15559e285384c742db52316802e24b0bdAl Virossize_t iov_iter_get_pages(struct iov_iter *i, 3207b2c99d15559e285384c742db52316802e24b0bdAl Viro struct page **pages, size_t maxsize, 3217b2c99d15559e285384c742db52316802e24b0bdAl Viro size_t *start) 3227b2c99d15559e285384c742db52316802e24b0bdAl Viro{ 3237b2c99d15559e285384c742db52316802e24b0bdAl Viro size_t offset = i->iov_offset; 3247b2c99d15559e285384c742db52316802e24b0bdAl Viro const struct iovec *iov = i->iov; 3257b2c99d15559e285384c742db52316802e24b0bdAl Viro size_t len; 3267b2c99d15559e285384c742db52316802e24b0bdAl Viro unsigned long addr; 3277b2c99d15559e285384c742db52316802e24b0bdAl Viro int n; 3287b2c99d15559e285384c742db52316802e24b0bdAl Viro int res; 3297b2c99d15559e285384c742db52316802e24b0bdAl Viro 3307b2c99d15559e285384c742db52316802e24b0bdAl Viro len = iov->iov_len - offset; 3317b2c99d15559e285384c742db52316802e24b0bdAl Viro if (len > i->count) 3327b2c99d15559e285384c742db52316802e24b0bdAl Viro len = i->count; 3337b2c99d15559e285384c742db52316802e24b0bdAl Viro if (len > maxsize) 3347b2c99d15559e285384c742db52316802e24b0bdAl Viro len = maxsize; 3357b2c99d15559e285384c742db52316802e24b0bdAl Viro addr = (unsigned long)iov->iov_base + offset; 3367b2c99d15559e285384c742db52316802e24b0bdAl Viro len += *start = addr & (PAGE_SIZE - 1); 3377b2c99d15559e285384c742db52316802e24b0bdAl Viro addr &= ~(PAGE_SIZE - 1); 3387b2c99d15559e285384c742db52316802e24b0bdAl Viro n = (len + PAGE_SIZE - 1) / PAGE_SIZE; 3397b2c99d15559e285384c742db52316802e24b0bdAl Viro res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages); 3407b2c99d15559e285384c742db52316802e24b0bdAl Viro if (unlikely(res < 0)) 3417b2c99d15559e285384c742db52316802e24b0bdAl Viro return res; 3427b2c99d15559e285384c742db52316802e24b0bdAl Viro return (res == n ? len : res * PAGE_SIZE) - *start; 3437b2c99d15559e285384c742db52316802e24b0bdAl Viro} 3447b2c99d15559e285384c742db52316802e24b0bdAl ViroEXPORT_SYMBOL(iov_iter_get_pages); 345f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro 34691f79c43d1b54d7154b118860d81b39bad07dfffAl Virossize_t iov_iter_get_pages_alloc(struct iov_iter *i, 34791f79c43d1b54d7154b118860d81b39bad07dfffAl Viro struct page ***pages, size_t maxsize, 34891f79c43d1b54d7154b118860d81b39bad07dfffAl Viro size_t *start) 34991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro{ 35091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro size_t offset = i->iov_offset; 35191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro const struct iovec *iov = i->iov; 35291f79c43d1b54d7154b118860d81b39bad07dfffAl Viro size_t len; 35391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro unsigned long addr; 35491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro void *p; 35591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro int n; 35691f79c43d1b54d7154b118860d81b39bad07dfffAl Viro int res; 35791f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 35891f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len = iov->iov_len - offset; 35991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (len > i->count) 36091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len = i->count; 36191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (len > maxsize) 36291f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len = maxsize; 36391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro addr = (unsigned long)iov->iov_base + offset; 36491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro len += *start = addr & (PAGE_SIZE - 1); 36591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro addr &= ~(PAGE_SIZE - 1); 36691f79c43d1b54d7154b118860d81b39bad07dfffAl Viro n = (len + PAGE_SIZE - 1) / PAGE_SIZE; 36791f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 36891f79c43d1b54d7154b118860d81b39bad07dfffAl Viro p = kmalloc(n * sizeof(struct page *), GFP_KERNEL); 36991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (!p) 37091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro p = vmalloc(n * sizeof(struct page *)); 37191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (!p) 37291f79c43d1b54d7154b118860d81b39bad07dfffAl Viro return -ENOMEM; 37391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 37491f79c43d1b54d7154b118860d81b39bad07dfffAl Viro res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p); 37591f79c43d1b54d7154b118860d81b39bad07dfffAl Viro if (unlikely(res < 0)) { 37691f79c43d1b54d7154b118860d81b39bad07dfffAl Viro kvfree(p); 37791f79c43d1b54d7154b118860d81b39bad07dfffAl Viro return res; 37891f79c43d1b54d7154b118860d81b39bad07dfffAl Viro } 37991f79c43d1b54d7154b118860d81b39bad07dfffAl Viro *pages = p; 38091f79c43d1b54d7154b118860d81b39bad07dfffAl Viro return (res == n ? len : res * PAGE_SIZE) - *start; 38191f79c43d1b54d7154b118860d81b39bad07dfffAl Viro} 38291f79c43d1b54d7154b118860d81b39bad07dfffAl ViroEXPORT_SYMBOL(iov_iter_get_pages_alloc); 38391f79c43d1b54d7154b118860d81b39bad07dfffAl Viro 384f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viroint iov_iter_npages(const struct iov_iter *i, int maxpages) 385f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro{ 386f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size_t offset = i->iov_offset; 387f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size_t size = i->count; 388f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro const struct iovec *iov = i->iov; 389f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro int npages = 0; 390f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro int n; 391f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro 392f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro for (n = 0; size && n < i->nr_segs; n++, iov++) { 393f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro unsigned long addr = (unsigned long)iov->iov_base + offset; 394f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size_t len = iov->iov_len - offset; 395f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro offset = 0; 396f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro if (unlikely(!len)) /* empty segment */ 397f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro continue; 398f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro if (len > size) 399f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro len = size; 400f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE 401f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro - addr / PAGE_SIZE; 402f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro if (npages >= maxpages) /* don't bother going further */ 403f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro return maxpages; 404f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro size -= len; 405f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro offset = 0; 406f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro } 407f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro return min(npages, maxpages); 408f67da30c1d5fc9e341bc8121708874bfd7b31e45Al Viro} 409f67da30c1d5fc9e341bc8121708874bfd7b31e45Al ViroEXPORT_SYMBOL(iov_iter_npages); 410