1457c8996SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 27999096fSHerbert Xu #include <crypto/hash.h> 3d879cb83SAl Viro #include <linux/export.h> 42f8b5444SChristoph Hellwig #include <linux/bvec.h> 54d0e9df5SAlbert van der Linde #include <linux/fault-inject-usercopy.h> 6d879cb83SAl Viro #include <linux/uio.h> 7d879cb83SAl Viro #include <linux/pagemap.h> 828961998SIra Weiny #include <linux/highmem.h> 9d879cb83SAl Viro #include <linux/slab.h> 10d879cb83SAl Viro #include <linux/vmalloc.h> 11241699cdSAl Viro #include <linux/splice.h> 12bfdc5970SChristoph Hellwig #include <linux/compat.h> 13d879cb83SAl Viro #include <net/checksum.h> 14d05f4435SSagi Grimberg #include <linux/scatterlist.h> 15d0ef4c36SMarco Elver #include <linux/instrumented.h> 16d879cb83SAl Viro 17241699cdSAl Viro #define PIPE_PARANOIA /* for now */ 18241699cdSAl Viro 195c67aa90SAl Viro /* covers iovec and kvec alike */ 20a6e4ec7bSAl Viro #define iterate_iovec(i, n, base, len, off, __p, STEP) { \ 217baa5099SAl Viro size_t off = 0; \ 22a6e4ec7bSAl Viro size_t skip = i->iov_offset; \ 237a1bcb5dSAl Viro do { \ 247baa5099SAl Viro len = min(n, __p->iov_len - skip); \ 257baa5099SAl Viro if (likely(len)) { \ 267baa5099SAl Viro base = __p->iov_base + skip; \ 277baa5099SAl Viro len -= (STEP); \ 287baa5099SAl Viro off += len; \ 297baa5099SAl Viro skip += len; \ 307baa5099SAl Viro n -= len; \ 317a1bcb5dSAl Viro if (skip < __p->iov_len) \ 327a1bcb5dSAl Viro break; \ 33d879cb83SAl Viro } \ 34d879cb83SAl Viro __p++; \ 357a1bcb5dSAl Viro skip = 0; \ 367a1bcb5dSAl Viro } while (n); \ 37a6e4ec7bSAl Viro i->iov_offset = skip; \ 387baa5099SAl Viro n = off; \ 39d879cb83SAl Viro } 40d879cb83SAl Viro 41a6e4ec7bSAl Viro #define iterate_bvec(i, n, base, len, off, p, STEP) { \ 427baa5099SAl Viro size_t off = 0; \ 43a6e4ec7bSAl Viro unsigned skip = i->iov_offset; \ 447491a2bfSAl Viro while (n) { \ 457491a2bfSAl Viro unsigned offset = p->bv_offset + skip; \ 461b4fb5ffSAl Viro unsigned left; \ 4721b56c84SAl Viro void *kaddr = kmap_local_page(p->bv_page + \ 4821b56c84SAl Viro offset / PAGE_SIZE); \ 497baa5099SAl Viro base = kaddr + offset % PAGE_SIZE; \ 50a6e4ec7bSAl Viro len = min(min(n, (size_t)(p->bv_len - skip)), \ 517491a2bfSAl Viro (size_t)(PAGE_SIZE - offset % PAGE_SIZE)); \ 521b4fb5ffSAl Viro left = (STEP); \ 5321b56c84SAl Viro kunmap_local(kaddr); \ 547baa5099SAl Viro len -= left; \ 557baa5099SAl Viro off += len; \ 567baa5099SAl Viro skip += len; \ 577491a2bfSAl Viro if (skip == p->bv_len) { \ 587491a2bfSAl Viro skip = 0; \ 597491a2bfSAl Viro p++; \ 60d879cb83SAl Viro } \ 617baa5099SAl Viro n -= len; \ 621b4fb5ffSAl Viro if (left) \ 631b4fb5ffSAl Viro break; \ 647491a2bfSAl Viro } \ 65a6e4ec7bSAl Viro i->iov_offset = skip; \ 667baa5099SAl Viro n = off; \ 67d879cb83SAl Viro } 68d879cb83SAl Viro 69a6e4ec7bSAl Viro #define iterate_xarray(i, n, base, len, __off, STEP) { \ 701b4fb5ffSAl Viro __label__ __out; \ 71622838f3SAl Viro size_t __off = 0; \ 72*821979f5SMatthew Wilcox (Oracle) struct folio *folio; \ 73a6e4ec7bSAl Viro loff_t start = i->xarray_start + i->iov_offset; \ 744b179e9aSAl Viro pgoff_t index = start / PAGE_SIZE; \ 757ff50620SDavid Howells XA_STATE(xas, i->xarray, index); \ 767ff50620SDavid Howells \ 77*821979f5SMatthew Wilcox (Oracle) len = PAGE_SIZE - offset_in_page(start); \ 787ff50620SDavid Howells rcu_read_lock(); \ 79*821979f5SMatthew Wilcox (Oracle) xas_for_each(&xas, folio, ULONG_MAX) { \ 801b4fb5ffSAl Viro unsigned left; \ 81*821979f5SMatthew Wilcox (Oracle) size_t offset; \ 82*821979f5SMatthew Wilcox (Oracle) if (xas_retry(&xas, folio)) \ 837ff50620SDavid Howells continue; \ 84*821979f5SMatthew Wilcox (Oracle) if (WARN_ON(xa_is_value(folio))) \ 857ff50620SDavid Howells break; \ 86*821979f5SMatthew Wilcox (Oracle) if (WARN_ON(folio_test_hugetlb(folio))) \ 877ff50620SDavid Howells break; \ 88*821979f5SMatthew Wilcox (Oracle) offset = offset_in_folio(folio, start + __off); \ 89*821979f5SMatthew Wilcox (Oracle) while (offset < folio_size(folio)) { \ 90*821979f5SMatthew Wilcox (Oracle) base = kmap_local_folio(folio, offset); \ 917baa5099SAl Viro len = min(n, len); \ 921b4fb5ffSAl Viro left = (STEP); \ 93*821979f5SMatthew Wilcox (Oracle) kunmap_local(base); \ 947baa5099SAl Viro len -= left; \ 957baa5099SAl Viro __off += len; \ 967baa5099SAl Viro n -= len; \ 971b4fb5ffSAl Viro if (left || n == 0) \ 981b4fb5ffSAl Viro goto __out; \ 99*821979f5SMatthew Wilcox (Oracle) offset += len; \ 100*821979f5SMatthew Wilcox (Oracle) len = PAGE_SIZE; \ 1017ff50620SDavid Howells } \ 1027ff50620SDavid Howells } \ 1031b4fb5ffSAl Viro __out: \ 1047ff50620SDavid Howells rcu_read_unlock(); \ 105a6e4ec7bSAl Viro i->iov_offset += __off; \ 106622838f3SAl Viro n = __off; \ 1077ff50620SDavid Howells } 1087ff50620SDavid Howells 1097baa5099SAl Viro #define __iterate_and_advance(i, n, base, len, off, I, K) { \ 110dd254f5aSAl Viro if (unlikely(i->count < n)) \ 111dd254f5aSAl Viro n = i->count; \ 112f5da8354SAl Viro if (likely(n)) { \ 11328f38db7SAl Viro if (likely(iter_is_iovec(i))) { \ 1145c67aa90SAl Viro const struct iovec *iov = i->iov; \ 1157baa5099SAl Viro void __user *base; \ 1167baa5099SAl Viro size_t len; \ 1177baa5099SAl Viro iterate_iovec(i, n, base, len, off, \ 118a6e4ec7bSAl Viro iov, (I)) \ 119d879cb83SAl Viro i->nr_segs -= iov - i->iov; \ 120d879cb83SAl Viro i->iov = iov; \ 12128f38db7SAl Viro } else if (iov_iter_is_bvec(i)) { \ 12228f38db7SAl Viro const struct bio_vec *bvec = i->bvec; \ 1237baa5099SAl Viro void *base; \ 1247baa5099SAl Viro size_t len; \ 1257baa5099SAl Viro iterate_bvec(i, n, base, len, off, \ 126a6e4ec7bSAl Viro bvec, (K)) \ 1277491a2bfSAl Viro i->nr_segs -= bvec - i->bvec; \ 1287491a2bfSAl Viro i->bvec = bvec; \ 12928f38db7SAl Viro } else if (iov_iter_is_kvec(i)) { \ 1305c67aa90SAl Viro const struct kvec *kvec = i->kvec; \ 1317baa5099SAl Viro void *base; \ 1327baa5099SAl Viro size_t len; \ 1337baa5099SAl Viro iterate_iovec(i, n, base, len, off, \ 134a6e4ec7bSAl Viro kvec, (K)) \ 13528f38db7SAl Viro i->nr_segs -= kvec - i->kvec; \ 13628f38db7SAl Viro i->kvec = kvec; \ 13728f38db7SAl Viro } else if (iov_iter_is_xarray(i)) { \ 1387baa5099SAl Viro void *base; \ 1397baa5099SAl Viro size_t len; \ 1407baa5099SAl Viro iterate_xarray(i, n, base, len, off, \ 141a6e4ec7bSAl Viro (K)) \ 142d879cb83SAl Viro } \ 143d879cb83SAl Viro i->count -= n; \ 144dd254f5aSAl Viro } \ 145d879cb83SAl Viro } 1467baa5099SAl Viro #define iterate_and_advance(i, n, base, len, off, I, K) \ 1477baa5099SAl Viro __iterate_and_advance(i, n, base, len, off, I, ((void)(K),0)) 148d879cb83SAl Viro 14909fc68dcSAl Viro static int copyout(void __user *to, const void *from, size_t n) 15009fc68dcSAl Viro { 1514d0e9df5SAlbert van der Linde if (should_fail_usercopy()) 1524d0e9df5SAlbert van der Linde return n; 15396d4f267SLinus Torvalds if (access_ok(to, n)) { 154d0ef4c36SMarco Elver instrument_copy_to_user(to, from, n); 15509fc68dcSAl Viro n = raw_copy_to_user(to, from, n); 15609fc68dcSAl Viro } 15709fc68dcSAl Viro return n; 15809fc68dcSAl Viro } 15909fc68dcSAl Viro 16009fc68dcSAl Viro static int copyin(void *to, const void __user *from, size_t n) 16109fc68dcSAl Viro { 1624d0e9df5SAlbert van der Linde if (should_fail_usercopy()) 1634d0e9df5SAlbert van der Linde return n; 16496d4f267SLinus Torvalds if (access_ok(from, n)) { 165d0ef4c36SMarco Elver instrument_copy_from_user(to, from, n); 16609fc68dcSAl Viro n = raw_copy_from_user(to, from, n); 16709fc68dcSAl Viro } 16809fc68dcSAl Viro return n; 16909fc68dcSAl Viro } 17009fc68dcSAl Viro 171d879cb83SAl Viro static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes, 172d879cb83SAl Viro struct iov_iter *i) 173d879cb83SAl Viro { 174d879cb83SAl Viro size_t skip, copy, left, wanted; 175d879cb83SAl Viro const struct iovec *iov; 176d879cb83SAl Viro char __user *buf; 177d879cb83SAl Viro void *kaddr, *from; 178d879cb83SAl Viro 179d879cb83SAl Viro if (unlikely(bytes > i->count)) 180d879cb83SAl Viro bytes = i->count; 181d879cb83SAl Viro 182d879cb83SAl Viro if (unlikely(!bytes)) 183d879cb83SAl Viro return 0; 184d879cb83SAl Viro 18509fc68dcSAl Viro might_fault(); 186d879cb83SAl Viro wanted = bytes; 187d879cb83SAl Viro iov = i->iov; 188d879cb83SAl Viro skip = i->iov_offset; 189d879cb83SAl Viro buf = iov->iov_base + skip; 190d879cb83SAl Viro copy = min(bytes, iov->iov_len - skip); 191d879cb83SAl Viro 192bb523b40SAndreas Gruenbacher if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_writeable(buf, copy)) { 193d879cb83SAl Viro kaddr = kmap_atomic(page); 194d879cb83SAl Viro from = kaddr + offset; 195d879cb83SAl Viro 196d879cb83SAl Viro /* first chunk, usually the only one */ 19709fc68dcSAl Viro left = copyout(buf, from, copy); 198d879cb83SAl Viro copy -= left; 199d879cb83SAl Viro skip += copy; 200d879cb83SAl Viro from += copy; 201d879cb83SAl Viro bytes -= copy; 202d879cb83SAl Viro 203d879cb83SAl Viro while (unlikely(!left && bytes)) { 204d879cb83SAl Viro iov++; 205d879cb83SAl Viro buf = iov->iov_base; 206d879cb83SAl Viro copy = min(bytes, iov->iov_len); 20709fc68dcSAl Viro left = copyout(buf, from, copy); 208d879cb83SAl Viro copy -= left; 209d879cb83SAl Viro skip = copy; 210d879cb83SAl Viro from += copy; 211d879cb83SAl Viro bytes -= copy; 212d879cb83SAl Viro } 213d879cb83SAl Viro if (likely(!bytes)) { 214d879cb83SAl Viro kunmap_atomic(kaddr); 215d879cb83SAl Viro goto done; 216d879cb83SAl Viro } 217d879cb83SAl Viro offset = from - kaddr; 218d879cb83SAl Viro buf += copy; 219d879cb83SAl Viro kunmap_atomic(kaddr); 220d879cb83SAl Viro copy = min(bytes, iov->iov_len - skip); 221d879cb83SAl Viro } 222d879cb83SAl Viro /* Too bad - revert to non-atomic kmap */ 2233fa6c507SMikulas Patocka 224d879cb83SAl Viro kaddr = kmap(page); 225d879cb83SAl Viro from = kaddr + offset; 22609fc68dcSAl Viro left = copyout(buf, from, copy); 227d879cb83SAl Viro copy -= left; 228d879cb83SAl Viro skip += copy; 229d879cb83SAl Viro from += copy; 230d879cb83SAl Viro bytes -= copy; 231d879cb83SAl Viro while (unlikely(!left && bytes)) { 232d879cb83SAl Viro iov++; 233d879cb83SAl Viro buf = iov->iov_base; 234d879cb83SAl Viro copy = min(bytes, iov->iov_len); 23509fc68dcSAl Viro left = copyout(buf, from, copy); 236d879cb83SAl Viro copy -= left; 237d879cb83SAl Viro skip = copy; 238d879cb83SAl Viro from += copy; 239d879cb83SAl Viro bytes -= copy; 240d879cb83SAl Viro } 241d879cb83SAl Viro kunmap(page); 2423fa6c507SMikulas Patocka 243d879cb83SAl Viro done: 244d879cb83SAl Viro if (skip == iov->iov_len) { 245d879cb83SAl Viro iov++; 246d879cb83SAl Viro skip = 0; 247d879cb83SAl Viro } 248d879cb83SAl Viro i->count -= wanted - bytes; 249d879cb83SAl Viro i->nr_segs -= iov - i->iov; 250d879cb83SAl Viro i->iov = iov; 251d879cb83SAl Viro i->iov_offset = skip; 252d879cb83SAl Viro return wanted - bytes; 253d879cb83SAl Viro } 254d879cb83SAl Viro 255d879cb83SAl Viro static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes, 256d879cb83SAl Viro struct iov_iter *i) 257d879cb83SAl Viro { 258d879cb83SAl Viro size_t skip, copy, left, wanted; 259d879cb83SAl Viro const struct iovec *iov; 260d879cb83SAl Viro char __user *buf; 261d879cb83SAl Viro void *kaddr, *to; 262d879cb83SAl Viro 263d879cb83SAl Viro if (unlikely(bytes > i->count)) 264d879cb83SAl Viro bytes = i->count; 265d879cb83SAl Viro 266d879cb83SAl Viro if (unlikely(!bytes)) 267d879cb83SAl Viro return 0; 268d879cb83SAl Viro 26909fc68dcSAl Viro might_fault(); 270d879cb83SAl Viro wanted = bytes; 271d879cb83SAl Viro iov = i->iov; 272d879cb83SAl Viro skip = i->iov_offset; 273d879cb83SAl Viro buf = iov->iov_base + skip; 274d879cb83SAl Viro copy = min(bytes, iov->iov_len - skip); 275d879cb83SAl Viro 276bb523b40SAndreas Gruenbacher if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_readable(buf, copy)) { 277d879cb83SAl Viro kaddr = kmap_atomic(page); 278d879cb83SAl Viro to = kaddr + offset; 279d879cb83SAl Viro 280d879cb83SAl Viro /* first chunk, usually the only one */ 28109fc68dcSAl Viro left = copyin(to, buf, copy); 282d879cb83SAl Viro copy -= left; 283d879cb83SAl Viro skip += copy; 284d879cb83SAl Viro to += copy; 285d879cb83SAl Viro bytes -= copy; 286d879cb83SAl Viro 287d879cb83SAl Viro while (unlikely(!left && bytes)) { 288d879cb83SAl Viro iov++; 289d879cb83SAl Viro buf = iov->iov_base; 290d879cb83SAl Viro copy = min(bytes, iov->iov_len); 29109fc68dcSAl Viro left = copyin(to, buf, copy); 292d879cb83SAl Viro copy -= left; 293d879cb83SAl Viro skip = copy; 294d879cb83SAl Viro to += copy; 295d879cb83SAl Viro bytes -= copy; 296d879cb83SAl Viro } 297d879cb83SAl Viro if (likely(!bytes)) { 298d879cb83SAl Viro kunmap_atomic(kaddr); 299d879cb83SAl Viro goto done; 300d879cb83SAl Viro } 301d879cb83SAl Viro offset = to - kaddr; 302d879cb83SAl Viro buf += copy; 303d879cb83SAl Viro kunmap_atomic(kaddr); 304d879cb83SAl Viro copy = min(bytes, iov->iov_len - skip); 305d879cb83SAl Viro } 306d879cb83SAl Viro /* Too bad - revert to non-atomic kmap */ 3073fa6c507SMikulas Patocka 308d879cb83SAl Viro kaddr = kmap(page); 309d879cb83SAl Viro to = kaddr + offset; 31009fc68dcSAl Viro left = copyin(to, buf, copy); 311d879cb83SAl Viro copy -= left; 312d879cb83SAl Viro skip += copy; 313d879cb83SAl Viro to += copy; 314d879cb83SAl Viro bytes -= copy; 315d879cb83SAl Viro while (unlikely(!left && bytes)) { 316d879cb83SAl Viro iov++; 317d879cb83SAl Viro buf = iov->iov_base; 318d879cb83SAl Viro copy = min(bytes, iov->iov_len); 31909fc68dcSAl Viro left = copyin(to, buf, copy); 320d879cb83SAl Viro copy -= left; 321d879cb83SAl Viro skip = copy; 322d879cb83SAl Viro to += copy; 323d879cb83SAl Viro bytes -= copy; 324d879cb83SAl Viro } 325d879cb83SAl Viro kunmap(page); 3263fa6c507SMikulas Patocka 327d879cb83SAl Viro done: 328d879cb83SAl Viro if (skip == iov->iov_len) { 329d879cb83SAl Viro iov++; 330d879cb83SAl Viro skip = 0; 331d879cb83SAl Viro } 332d879cb83SAl Viro i->count -= wanted - bytes; 333d879cb83SAl Viro i->nr_segs -= iov - i->iov; 334d879cb83SAl Viro i->iov = iov; 335d879cb83SAl Viro i->iov_offset = skip; 336d879cb83SAl Viro return wanted - bytes; 337d879cb83SAl Viro } 338d879cb83SAl Viro 339241699cdSAl Viro #ifdef PIPE_PARANOIA 340241699cdSAl Viro static bool sanity(const struct iov_iter *i) 341241699cdSAl Viro { 342241699cdSAl Viro struct pipe_inode_info *pipe = i->pipe; 3438cefc107SDavid Howells unsigned int p_head = pipe->head; 3448cefc107SDavid Howells unsigned int p_tail = pipe->tail; 3458cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 3468cefc107SDavid Howells unsigned int p_occupancy = pipe_occupancy(p_head, p_tail); 3478cefc107SDavid Howells unsigned int i_head = i->head; 3488cefc107SDavid Howells unsigned int idx; 3498cefc107SDavid Howells 350241699cdSAl Viro if (i->iov_offset) { 351241699cdSAl Viro struct pipe_buffer *p; 3528cefc107SDavid Howells if (unlikely(p_occupancy == 0)) 353241699cdSAl Viro goto Bad; // pipe must be non-empty 3548cefc107SDavid Howells if (unlikely(i_head != p_head - 1)) 355241699cdSAl Viro goto Bad; // must be at the last buffer... 356241699cdSAl Viro 3578cefc107SDavid Howells p = &pipe->bufs[i_head & p_mask]; 358241699cdSAl Viro if (unlikely(p->offset + p->len != i->iov_offset)) 359241699cdSAl Viro goto Bad; // ... at the end of segment 360241699cdSAl Viro } else { 3618cefc107SDavid Howells if (i_head != p_head) 362241699cdSAl Viro goto Bad; // must be right after the last buffer 363241699cdSAl Viro } 364241699cdSAl Viro return true; 365241699cdSAl Viro Bad: 3668cefc107SDavid Howells printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset); 3678cefc107SDavid Howells printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n", 3688cefc107SDavid Howells p_head, p_tail, pipe->ring_size); 3698cefc107SDavid Howells for (idx = 0; idx < pipe->ring_size; idx++) 370241699cdSAl Viro printk(KERN_ERR "[%p %p %d %d]\n", 371241699cdSAl Viro pipe->bufs[idx].ops, 372241699cdSAl Viro pipe->bufs[idx].page, 373241699cdSAl Viro pipe->bufs[idx].offset, 374241699cdSAl Viro pipe->bufs[idx].len); 375241699cdSAl Viro WARN_ON(1); 376241699cdSAl Viro return false; 377241699cdSAl Viro } 378241699cdSAl Viro #else 379241699cdSAl Viro #define sanity(i) true 380241699cdSAl Viro #endif 381241699cdSAl Viro 382241699cdSAl Viro static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes, 383241699cdSAl Viro struct iov_iter *i) 384241699cdSAl Viro { 385241699cdSAl Viro struct pipe_inode_info *pipe = i->pipe; 386241699cdSAl Viro struct pipe_buffer *buf; 3878cefc107SDavid Howells unsigned int p_tail = pipe->tail; 3888cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 3898cefc107SDavid Howells unsigned int i_head = i->head; 390241699cdSAl Viro size_t off; 391241699cdSAl Viro 392241699cdSAl Viro if (unlikely(bytes > i->count)) 393241699cdSAl Viro bytes = i->count; 394241699cdSAl Viro 395241699cdSAl Viro if (unlikely(!bytes)) 396241699cdSAl Viro return 0; 397241699cdSAl Viro 398241699cdSAl Viro if (!sanity(i)) 399241699cdSAl Viro return 0; 400241699cdSAl Viro 401241699cdSAl Viro off = i->iov_offset; 4028cefc107SDavid Howells buf = &pipe->bufs[i_head & p_mask]; 403241699cdSAl Viro if (off) { 404241699cdSAl Viro if (offset == off && buf->page == page) { 405241699cdSAl Viro /* merge with the last one */ 406241699cdSAl Viro buf->len += bytes; 407241699cdSAl Viro i->iov_offset += bytes; 408241699cdSAl Viro goto out; 409241699cdSAl Viro } 4108cefc107SDavid Howells i_head++; 4118cefc107SDavid Howells buf = &pipe->bufs[i_head & p_mask]; 412241699cdSAl Viro } 4136718b6f8SDavid Howells if (pipe_full(i_head, p_tail, pipe->max_usage)) 414241699cdSAl Viro return 0; 4158cefc107SDavid Howells 416241699cdSAl Viro buf->ops = &page_cache_pipe_buf_ops; 4178cefc107SDavid Howells get_page(page); 4188cefc107SDavid Howells buf->page = page; 419241699cdSAl Viro buf->offset = offset; 420241699cdSAl Viro buf->len = bytes; 4218cefc107SDavid Howells 4228cefc107SDavid Howells pipe->head = i_head + 1; 423241699cdSAl Viro i->iov_offset = offset + bytes; 4248cefc107SDavid Howells i->head = i_head; 425241699cdSAl Viro out: 426241699cdSAl Viro i->count -= bytes; 427241699cdSAl Viro return bytes; 428241699cdSAl Viro } 429241699cdSAl Viro 430d879cb83SAl Viro /* 431a6294593SAndreas Gruenbacher * fault_in_iov_iter_readable - fault in iov iterator for reading 432a6294593SAndreas Gruenbacher * @i: iterator 433a6294593SAndreas Gruenbacher * @size: maximum length 434171a0203SAnton Altaparmakov * 435a6294593SAndreas Gruenbacher * Fault in one or more iovecs of the given iov_iter, to a maximum length of 436a6294593SAndreas Gruenbacher * @size. For each iovec, fault in each page that constitutes the iovec. 437a6294593SAndreas Gruenbacher * 438a6294593SAndreas Gruenbacher * Returns the number of bytes not faulted in (like copy_to_user() and 439a6294593SAndreas Gruenbacher * copy_from_user()). 440a6294593SAndreas Gruenbacher * 441a6294593SAndreas Gruenbacher * Always returns 0 for non-userspace iterators. 442171a0203SAnton Altaparmakov */ 443a6294593SAndreas Gruenbacher size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size) 444171a0203SAnton Altaparmakov { 4450e8f0d67SAl Viro if (iter_is_iovec(i)) { 446a6294593SAndreas Gruenbacher size_t count = min(size, iov_iter_count(i)); 4478409a0d2SAl Viro const struct iovec *p; 4488409a0d2SAl Viro size_t skip; 4498409a0d2SAl Viro 450a6294593SAndreas Gruenbacher size -= count; 451a6294593SAndreas Gruenbacher for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { 452a6294593SAndreas Gruenbacher size_t len = min(count, p->iov_len - skip); 453a6294593SAndreas Gruenbacher size_t ret; 4548409a0d2SAl Viro 4558409a0d2SAl Viro if (unlikely(!len)) 4568409a0d2SAl Viro continue; 457a6294593SAndreas Gruenbacher ret = fault_in_readable(p->iov_base + skip, len); 458a6294593SAndreas Gruenbacher count -= len - ret; 459a6294593SAndreas Gruenbacher if (ret) 460a6294593SAndreas Gruenbacher break; 4618409a0d2SAl Viro } 462a6294593SAndreas Gruenbacher return count + size; 463171a0203SAnton Altaparmakov } 464171a0203SAnton Altaparmakov return 0; 465171a0203SAnton Altaparmakov } 466a6294593SAndreas Gruenbacher EXPORT_SYMBOL(fault_in_iov_iter_readable); 467171a0203SAnton Altaparmakov 468cdd591fcSAndreas Gruenbacher /* 469cdd591fcSAndreas Gruenbacher * fault_in_iov_iter_writeable - fault in iov iterator for writing 470cdd591fcSAndreas Gruenbacher * @i: iterator 471cdd591fcSAndreas Gruenbacher * @size: maximum length 472cdd591fcSAndreas Gruenbacher * 473cdd591fcSAndreas Gruenbacher * Faults in the iterator using get_user_pages(), i.e., without triggering 474cdd591fcSAndreas Gruenbacher * hardware page faults. This is primarily useful when we already know that 475cdd591fcSAndreas Gruenbacher * some or all of the pages in @i aren't in memory. 476cdd591fcSAndreas Gruenbacher * 477cdd591fcSAndreas Gruenbacher * Returns the number of bytes not faulted in, like copy_to_user() and 478cdd591fcSAndreas Gruenbacher * copy_from_user(). 479cdd591fcSAndreas Gruenbacher * 480cdd591fcSAndreas Gruenbacher * Always returns 0 for non-user-space iterators. 481cdd591fcSAndreas Gruenbacher */ 482cdd591fcSAndreas Gruenbacher size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size) 483cdd591fcSAndreas Gruenbacher { 484cdd591fcSAndreas Gruenbacher if (iter_is_iovec(i)) { 485cdd591fcSAndreas Gruenbacher size_t count = min(size, iov_iter_count(i)); 486cdd591fcSAndreas Gruenbacher const struct iovec *p; 487cdd591fcSAndreas Gruenbacher size_t skip; 488cdd591fcSAndreas Gruenbacher 489cdd591fcSAndreas Gruenbacher size -= count; 490cdd591fcSAndreas Gruenbacher for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { 491cdd591fcSAndreas Gruenbacher size_t len = min(count, p->iov_len - skip); 492cdd591fcSAndreas Gruenbacher size_t ret; 493cdd591fcSAndreas Gruenbacher 494cdd591fcSAndreas Gruenbacher if (unlikely(!len)) 495cdd591fcSAndreas Gruenbacher continue; 496cdd591fcSAndreas Gruenbacher ret = fault_in_safe_writeable(p->iov_base + skip, len); 497cdd591fcSAndreas Gruenbacher count -= len - ret; 498cdd591fcSAndreas Gruenbacher if (ret) 499cdd591fcSAndreas Gruenbacher break; 500cdd591fcSAndreas Gruenbacher } 501cdd591fcSAndreas Gruenbacher return count + size; 502cdd591fcSAndreas Gruenbacher } 503cdd591fcSAndreas Gruenbacher return 0; 504cdd591fcSAndreas Gruenbacher } 505cdd591fcSAndreas Gruenbacher EXPORT_SYMBOL(fault_in_iov_iter_writeable); 506cdd591fcSAndreas Gruenbacher 507aa563d7bSDavid Howells void iov_iter_init(struct iov_iter *i, unsigned int direction, 508d879cb83SAl Viro const struct iovec *iov, unsigned long nr_segs, 509d879cb83SAl Viro size_t count) 510d879cb83SAl Viro { 511aa563d7bSDavid Howells WARN_ON(direction & ~(READ | WRITE)); 5128cd54c1cSAl Viro *i = (struct iov_iter) { 5138cd54c1cSAl Viro .iter_type = ITER_IOVEC, 5143337ab08SAndreas Gruenbacher .nofault = false, 5158cd54c1cSAl Viro .data_source = direction, 5168cd54c1cSAl Viro .iov = iov, 5178cd54c1cSAl Viro .nr_segs = nr_segs, 5188cd54c1cSAl Viro .iov_offset = 0, 5198cd54c1cSAl Viro .count = count 5208cd54c1cSAl Viro }; 521d879cb83SAl Viro } 522d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_init); 523d879cb83SAl Viro 524241699cdSAl Viro static inline bool allocated(struct pipe_buffer *buf) 525241699cdSAl Viro { 526241699cdSAl Viro return buf->ops == &default_pipe_buf_ops; 527241699cdSAl Viro } 528241699cdSAl Viro 5298cefc107SDavid Howells static inline void data_start(const struct iov_iter *i, 5308cefc107SDavid Howells unsigned int *iter_headp, size_t *offp) 531241699cdSAl Viro { 5328cefc107SDavid Howells unsigned int p_mask = i->pipe->ring_size - 1; 5338cefc107SDavid Howells unsigned int iter_head = i->head; 534241699cdSAl Viro size_t off = i->iov_offset; 5358cefc107SDavid Howells 5368cefc107SDavid Howells if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) || 5378cefc107SDavid Howells off == PAGE_SIZE)) { 5388cefc107SDavid Howells iter_head++; 539241699cdSAl Viro off = 0; 540241699cdSAl Viro } 5418cefc107SDavid Howells *iter_headp = iter_head; 542241699cdSAl Viro *offp = off; 543241699cdSAl Viro } 544241699cdSAl Viro 545241699cdSAl Viro static size_t push_pipe(struct iov_iter *i, size_t size, 5468cefc107SDavid Howells int *iter_headp, size_t *offp) 547241699cdSAl Viro { 548241699cdSAl Viro struct pipe_inode_info *pipe = i->pipe; 5498cefc107SDavid Howells unsigned int p_tail = pipe->tail; 5508cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 5518cefc107SDavid Howells unsigned int iter_head; 552241699cdSAl Viro size_t off; 553241699cdSAl Viro ssize_t left; 554241699cdSAl Viro 555241699cdSAl Viro if (unlikely(size > i->count)) 556241699cdSAl Viro size = i->count; 557241699cdSAl Viro if (unlikely(!size)) 558241699cdSAl Viro return 0; 559241699cdSAl Viro 560241699cdSAl Viro left = size; 5618cefc107SDavid Howells data_start(i, &iter_head, &off); 5628cefc107SDavid Howells *iter_headp = iter_head; 563241699cdSAl Viro *offp = off; 564241699cdSAl Viro if (off) { 565241699cdSAl Viro left -= PAGE_SIZE - off; 566241699cdSAl Viro if (left <= 0) { 5678cefc107SDavid Howells pipe->bufs[iter_head & p_mask].len += size; 568241699cdSAl Viro return size; 569241699cdSAl Viro } 5708cefc107SDavid Howells pipe->bufs[iter_head & p_mask].len = PAGE_SIZE; 5718cefc107SDavid Howells iter_head++; 572241699cdSAl Viro } 5736718b6f8SDavid Howells while (!pipe_full(iter_head, p_tail, pipe->max_usage)) { 5748cefc107SDavid Howells struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask]; 575241699cdSAl Viro struct page *page = alloc_page(GFP_USER); 576241699cdSAl Viro if (!page) 577241699cdSAl Viro break; 5788cefc107SDavid Howells 5798cefc107SDavid Howells buf->ops = &default_pipe_buf_ops; 5808cefc107SDavid Howells buf->page = page; 5818cefc107SDavid Howells buf->offset = 0; 5828cefc107SDavid Howells buf->len = min_t(ssize_t, left, PAGE_SIZE); 5838cefc107SDavid Howells left -= buf->len; 5848cefc107SDavid Howells iter_head++; 5858cefc107SDavid Howells pipe->head = iter_head; 5868cefc107SDavid Howells 5878cefc107SDavid Howells if (left == 0) 588241699cdSAl Viro return size; 589241699cdSAl Viro } 590241699cdSAl Viro return size - left; 591241699cdSAl Viro } 592241699cdSAl Viro 593241699cdSAl Viro static size_t copy_pipe_to_iter(const void *addr, size_t bytes, 594241699cdSAl Viro struct iov_iter *i) 595241699cdSAl Viro { 596241699cdSAl Viro struct pipe_inode_info *pipe = i->pipe; 5978cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 5988cefc107SDavid Howells unsigned int i_head; 599241699cdSAl Viro size_t n, off; 600241699cdSAl Viro 601241699cdSAl Viro if (!sanity(i)) 602241699cdSAl Viro return 0; 603241699cdSAl Viro 6048cefc107SDavid Howells bytes = n = push_pipe(i, bytes, &i_head, &off); 605241699cdSAl Viro if (unlikely(!n)) 606241699cdSAl Viro return 0; 6078cefc107SDavid Howells do { 608241699cdSAl Viro size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 6098cefc107SDavid Howells memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk); 6108cefc107SDavid Howells i->head = i_head; 611241699cdSAl Viro i->iov_offset = off + chunk; 612241699cdSAl Viro n -= chunk; 613241699cdSAl Viro addr += chunk; 6148cefc107SDavid Howells off = 0; 6158cefc107SDavid Howells i_head++; 6168cefc107SDavid Howells } while (n); 617241699cdSAl Viro i->count -= bytes; 618241699cdSAl Viro return bytes; 619241699cdSAl Viro } 620241699cdSAl Viro 621f9152895SAl Viro static __wsum csum_and_memcpy(void *to, const void *from, size_t len, 622f9152895SAl Viro __wsum sum, size_t off) 623f9152895SAl Viro { 624cc44c17bSAl Viro __wsum next = csum_partial_copy_nocheck(from, to, len); 625f9152895SAl Viro return csum_block_add(sum, next, off); 626f9152895SAl Viro } 627f9152895SAl Viro 62878e1f386SAl Viro static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, 6296852df12SAl Viro struct iov_iter *i, __wsum *sump) 63078e1f386SAl Viro { 63178e1f386SAl Viro struct pipe_inode_info *pipe = i->pipe; 6328cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 6336852df12SAl Viro __wsum sum = *sump; 6346852df12SAl Viro size_t off = 0; 6358cefc107SDavid Howells unsigned int i_head; 6366852df12SAl Viro size_t r; 63778e1f386SAl Viro 63878e1f386SAl Viro if (!sanity(i)) 63978e1f386SAl Viro return 0; 64078e1f386SAl Viro 6416852df12SAl Viro bytes = push_pipe(i, bytes, &i_head, &r); 6426852df12SAl Viro while (bytes) { 6436852df12SAl Viro size_t chunk = min_t(size_t, bytes, PAGE_SIZE - r); 6442495bdccSAl Viro char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); 6456852df12SAl Viro sum = csum_and_memcpy(p + r, addr + off, chunk, sum, off); 6462495bdccSAl Viro kunmap_local(p); 6478cefc107SDavid Howells i->head = i_head; 64878e1f386SAl Viro i->iov_offset = r + chunk; 6496852df12SAl Viro bytes -= chunk; 65078e1f386SAl Viro off += chunk; 6518cefc107SDavid Howells r = 0; 6528cefc107SDavid Howells i_head++; 6536852df12SAl Viro } 6546852df12SAl Viro *sump = sum; 6556852df12SAl Viro i->count -= off; 6566852df12SAl Viro return off; 65778e1f386SAl Viro } 65878e1f386SAl Viro 659aa28de27SAl Viro size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 660d879cb83SAl Viro { 66100e23707SDavid Howells if (unlikely(iov_iter_is_pipe(i))) 662241699cdSAl Viro return copy_pipe_to_iter(addr, bytes, i); 66309fc68dcSAl Viro if (iter_is_iovec(i)) 66409fc68dcSAl Viro might_fault(); 6657baa5099SAl Viro iterate_and_advance(i, bytes, base, len, off, 6667baa5099SAl Viro copyout(base, addr + off, len), 6677baa5099SAl Viro memcpy(base, addr + off, len) 668d879cb83SAl Viro ) 669d879cb83SAl Viro 670d879cb83SAl Viro return bytes; 671d879cb83SAl Viro } 672aa28de27SAl Viro EXPORT_SYMBOL(_copy_to_iter); 673d879cb83SAl Viro 674ec6347bbSDan Williams #ifdef CONFIG_ARCH_HAS_COPY_MC 675ec6347bbSDan Williams static int copyout_mc(void __user *to, const void *from, size_t n) 6768780356eSDan Williams { 67796d4f267SLinus Torvalds if (access_ok(to, n)) { 678d0ef4c36SMarco Elver instrument_copy_to_user(to, from, n); 679ec6347bbSDan Williams n = copy_mc_to_user((__force void *) to, from, n); 6808780356eSDan Williams } 6818780356eSDan Williams return n; 6828780356eSDan Williams } 6838780356eSDan Williams 684ec6347bbSDan Williams static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes, 685ca146f6fSDan Williams struct iov_iter *i) 686ca146f6fSDan Williams { 687ca146f6fSDan Williams struct pipe_inode_info *pipe = i->pipe; 6888cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 6898cefc107SDavid Howells unsigned int i_head; 690ca146f6fSDan Williams size_t n, off, xfer = 0; 691ca146f6fSDan Williams 692ca146f6fSDan Williams if (!sanity(i)) 693ca146f6fSDan Williams return 0; 694ca146f6fSDan Williams 6952a510a74SAl Viro n = push_pipe(i, bytes, &i_head, &off); 6962a510a74SAl Viro while (n) { 697ca146f6fSDan Williams size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 6982a510a74SAl Viro char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); 699ca146f6fSDan Williams unsigned long rem; 7002a510a74SAl Viro rem = copy_mc_to_kernel(p + off, addr + xfer, chunk); 7012a510a74SAl Viro chunk -= rem; 7022a510a74SAl Viro kunmap_local(p); 7038cefc107SDavid Howells i->head = i_head; 7042a510a74SAl Viro i->iov_offset = off + chunk; 7052a510a74SAl Viro xfer += chunk; 706ca146f6fSDan Williams if (rem) 707ca146f6fSDan Williams break; 708ca146f6fSDan Williams n -= chunk; 7098cefc107SDavid Howells off = 0; 7108cefc107SDavid Howells i_head++; 7112a510a74SAl Viro } 712ca146f6fSDan Williams i->count -= xfer; 713ca146f6fSDan Williams return xfer; 714ca146f6fSDan Williams } 715ca146f6fSDan Williams 716bf3eeb9bSDan Williams /** 717ec6347bbSDan Williams * _copy_mc_to_iter - copy to iter with source memory error exception handling 718bf3eeb9bSDan Williams * @addr: source kernel address 719bf3eeb9bSDan Williams * @bytes: total transfer length 72044e55997SRandy Dunlap * @i: destination iterator 721bf3eeb9bSDan Williams * 722ec6347bbSDan Williams * The pmem driver deploys this for the dax operation 723ec6347bbSDan Williams * (dax_copy_to_iter()) for dax reads (bypass page-cache and the 724ec6347bbSDan Williams * block-layer). Upon #MC read(2) aborts and returns EIO or the bytes 725ec6347bbSDan Williams * successfully copied. 726bf3eeb9bSDan Williams * 727ec6347bbSDan Williams * The main differences between this and typical _copy_to_iter(). 728bf3eeb9bSDan Williams * 729bf3eeb9bSDan Williams * * Typical tail/residue handling after a fault retries the copy 730bf3eeb9bSDan Williams * byte-by-byte until the fault happens again. Re-triggering machine 731bf3eeb9bSDan Williams * checks is potentially fatal so the implementation uses source 732bf3eeb9bSDan Williams * alignment and poison alignment assumptions to avoid re-triggering 733bf3eeb9bSDan Williams * hardware exceptions. 734bf3eeb9bSDan Williams * 735bf3eeb9bSDan Williams * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies. 736bf3eeb9bSDan Williams * Compare to copy_to_iter() where only ITER_IOVEC attempts might return 737bf3eeb9bSDan Williams * a short copy. 73844e55997SRandy Dunlap * 73944e55997SRandy Dunlap * Return: number of bytes copied (may be %0) 740bf3eeb9bSDan Williams */ 741ec6347bbSDan Williams size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) 7428780356eSDan Williams { 74300e23707SDavid Howells if (unlikely(iov_iter_is_pipe(i))) 744ec6347bbSDan Williams return copy_mc_pipe_to_iter(addr, bytes, i); 7458780356eSDan Williams if (iter_is_iovec(i)) 7468780356eSDan Williams might_fault(); 7477baa5099SAl Viro __iterate_and_advance(i, bytes, base, len, off, 7487baa5099SAl Viro copyout_mc(base, addr + off, len), 7497baa5099SAl Viro copy_mc_to_kernel(base, addr + off, len) 7508780356eSDan Williams ) 7518780356eSDan Williams 7528780356eSDan Williams return bytes; 7538780356eSDan Williams } 754ec6347bbSDan Williams EXPORT_SYMBOL_GPL(_copy_mc_to_iter); 755ec6347bbSDan Williams #endif /* CONFIG_ARCH_HAS_COPY_MC */ 7568780356eSDan Williams 757aa28de27SAl Viro size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) 758d879cb83SAl Viro { 75900e23707SDavid Howells if (unlikely(iov_iter_is_pipe(i))) { 760241699cdSAl Viro WARN_ON(1); 761241699cdSAl Viro return 0; 762241699cdSAl Viro } 76309fc68dcSAl Viro if (iter_is_iovec(i)) 76409fc68dcSAl Viro might_fault(); 7657baa5099SAl Viro iterate_and_advance(i, bytes, base, len, off, 7667baa5099SAl Viro copyin(addr + off, base, len), 7677baa5099SAl Viro memcpy(addr + off, base, len) 768d879cb83SAl Viro ) 769d879cb83SAl Viro 770d879cb83SAl Viro return bytes; 771d879cb83SAl Viro } 772aa28de27SAl Viro EXPORT_SYMBOL(_copy_from_iter); 773d879cb83SAl Viro 774aa28de27SAl Viro size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) 775d879cb83SAl Viro { 77600e23707SDavid Howells if (unlikely(iov_iter_is_pipe(i))) { 777241699cdSAl Viro WARN_ON(1); 778241699cdSAl Viro return 0; 779241699cdSAl Viro } 7807baa5099SAl Viro iterate_and_advance(i, bytes, base, len, off, 7817baa5099SAl Viro __copy_from_user_inatomic_nocache(addr + off, base, len), 7827baa5099SAl Viro memcpy(addr + off, base, len) 783d879cb83SAl Viro ) 784d879cb83SAl Viro 785d879cb83SAl Viro return bytes; 786d879cb83SAl Viro } 787aa28de27SAl Viro EXPORT_SYMBOL(_copy_from_iter_nocache); 788d879cb83SAl Viro 7890aed55afSDan Williams #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 790abd08d7dSDan Williams /** 791abd08d7dSDan Williams * _copy_from_iter_flushcache - write destination through cpu cache 792abd08d7dSDan Williams * @addr: destination kernel address 793abd08d7dSDan Williams * @bytes: total transfer length 79444e55997SRandy Dunlap * @i: source iterator 795abd08d7dSDan Williams * 796abd08d7dSDan Williams * The pmem driver arranges for filesystem-dax to use this facility via 797abd08d7dSDan Williams * dax_copy_from_iter() for ensuring that writes to persistent memory 798abd08d7dSDan Williams * are flushed through the CPU cache. It is differentiated from 799abd08d7dSDan Williams * _copy_from_iter_nocache() in that guarantees all data is flushed for 800abd08d7dSDan Williams * all iterator types. The _copy_from_iter_nocache() only attempts to 801abd08d7dSDan Williams * bypass the cache for the ITER_IOVEC case, and on some archs may use 802abd08d7dSDan Williams * instructions that strand dirty-data in the cache. 80344e55997SRandy Dunlap * 80444e55997SRandy Dunlap * Return: number of bytes copied (may be %0) 805abd08d7dSDan Williams */ 8066a37e940SLinus Torvalds size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i) 8070aed55afSDan Williams { 80800e23707SDavid Howells if (unlikely(iov_iter_is_pipe(i))) { 8090aed55afSDan Williams WARN_ON(1); 8100aed55afSDan Williams return 0; 8110aed55afSDan Williams } 8127baa5099SAl Viro iterate_and_advance(i, bytes, base, len, off, 8137baa5099SAl Viro __copy_from_user_flushcache(addr + off, base, len), 8147baa5099SAl Viro memcpy_flushcache(addr + off, base, len) 8150aed55afSDan Williams ) 8160aed55afSDan Williams 8170aed55afSDan Williams return bytes; 8180aed55afSDan Williams } 8196a37e940SLinus Torvalds EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache); 8200aed55afSDan Williams #endif 8210aed55afSDan Williams 82272e809edSAl Viro static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) 82372e809edSAl Viro { 8246daef95bSEric Dumazet struct page *head; 8256daef95bSEric Dumazet size_t v = n + offset; 8266daef95bSEric Dumazet 8276daef95bSEric Dumazet /* 8286daef95bSEric Dumazet * The general case needs to access the page order in order 8296daef95bSEric Dumazet * to compute the page size. 8306daef95bSEric Dumazet * However, we mostly deal with order-0 pages and thus can 8316daef95bSEric Dumazet * avoid a possible cache line miss for requests that fit all 8326daef95bSEric Dumazet * page orders. 8336daef95bSEric Dumazet */ 8346daef95bSEric Dumazet if (n <= v && v <= PAGE_SIZE) 8356daef95bSEric Dumazet return true; 8366daef95bSEric Dumazet 8376daef95bSEric Dumazet head = compound_head(page); 8386daef95bSEric Dumazet v += (page - head) << PAGE_SHIFT; 839a90bcb86SPetar Penkov 840a50b854eSMatthew Wilcox (Oracle) if (likely(n <= v && v <= (page_size(head)))) 84172e809edSAl Viro return true; 84272e809edSAl Viro WARN_ON(1); 84372e809edSAl Viro return false; 84472e809edSAl Viro } 845cbbd26b8SAl Viro 84608aa6479SAl Viro static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 847d879cb83SAl Viro struct iov_iter *i) 848d879cb83SAl Viro { 84928f38db7SAl Viro if (likely(iter_is_iovec(i))) 85028f38db7SAl Viro return copy_page_to_iter_iovec(page, offset, bytes, i); 85128f38db7SAl Viro if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) { 852c1d4d6a9SAl Viro void *kaddr = kmap_local_page(page); 853c1d4d6a9SAl Viro size_t wanted = _copy_to_iter(kaddr + offset, bytes, i); 854c1d4d6a9SAl Viro kunmap_local(kaddr); 855d879cb83SAl Viro return wanted; 85628f38db7SAl Viro } 85728f38db7SAl Viro if (iov_iter_is_pipe(i)) 85828f38db7SAl Viro return copy_page_to_iter_pipe(page, offset, bytes, i); 85928f38db7SAl Viro if (unlikely(iov_iter_is_discard(i))) { 860a506abc7SAl Viro if (unlikely(i->count < bytes)) 861a506abc7SAl Viro bytes = i->count; 862a506abc7SAl Viro i->count -= bytes; 8639ea9ce04SDavid Howells return bytes; 86428f38db7SAl Viro } 86528f38db7SAl Viro WARN_ON(1); 86628f38db7SAl Viro return 0; 867d879cb83SAl Viro } 86808aa6479SAl Viro 86908aa6479SAl Viro size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 87008aa6479SAl Viro struct iov_iter *i) 87108aa6479SAl Viro { 87208aa6479SAl Viro size_t res = 0; 87308aa6479SAl Viro if (unlikely(!page_copy_sane(page, offset, bytes))) 87408aa6479SAl Viro return 0; 87508aa6479SAl Viro page += offset / PAGE_SIZE; // first subpage 87608aa6479SAl Viro offset %= PAGE_SIZE; 87708aa6479SAl Viro while (1) { 87808aa6479SAl Viro size_t n = __copy_page_to_iter(page, offset, 87908aa6479SAl Viro min(bytes, (size_t)PAGE_SIZE - offset), i); 88008aa6479SAl Viro res += n; 88108aa6479SAl Viro bytes -= n; 88208aa6479SAl Viro if (!bytes || !n) 88308aa6479SAl Viro break; 88408aa6479SAl Viro offset += n; 88508aa6479SAl Viro if (offset == PAGE_SIZE) { 88608aa6479SAl Viro page++; 88708aa6479SAl Viro offset = 0; 88808aa6479SAl Viro } 88908aa6479SAl Viro } 89008aa6479SAl Viro return res; 89108aa6479SAl Viro } 892d879cb83SAl Viro EXPORT_SYMBOL(copy_page_to_iter); 893d879cb83SAl Viro 894d879cb83SAl Viro size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, 895d879cb83SAl Viro struct iov_iter *i) 896d879cb83SAl Viro { 89772e809edSAl Viro if (unlikely(!page_copy_sane(page, offset, bytes))) 89872e809edSAl Viro return 0; 89928f38db7SAl Viro if (likely(iter_is_iovec(i))) 90028f38db7SAl Viro return copy_page_from_iter_iovec(page, offset, bytes, i); 90128f38db7SAl Viro if (iov_iter_is_bvec(i) || iov_iter_is_kvec(i) || iov_iter_is_xarray(i)) { 90255ca375cSAl Viro void *kaddr = kmap_local_page(page); 903aa28de27SAl Viro size_t wanted = _copy_from_iter(kaddr + offset, bytes, i); 90455ca375cSAl Viro kunmap_local(kaddr); 905d879cb83SAl Viro return wanted; 90628f38db7SAl Viro } 90728f38db7SAl Viro WARN_ON(1); 90828f38db7SAl Viro return 0; 909d879cb83SAl Viro } 910d879cb83SAl Viro EXPORT_SYMBOL(copy_page_from_iter); 911d879cb83SAl Viro 912241699cdSAl Viro static size_t pipe_zero(size_t bytes, struct iov_iter *i) 913241699cdSAl Viro { 914241699cdSAl Viro struct pipe_inode_info *pipe = i->pipe; 9158cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 9168cefc107SDavid Howells unsigned int i_head; 917241699cdSAl Viro size_t n, off; 918241699cdSAl Viro 919241699cdSAl Viro if (!sanity(i)) 920241699cdSAl Viro return 0; 921241699cdSAl Viro 9228cefc107SDavid Howells bytes = n = push_pipe(i, bytes, &i_head, &off); 923241699cdSAl Viro if (unlikely(!n)) 924241699cdSAl Viro return 0; 925241699cdSAl Viro 9268cefc107SDavid Howells do { 927241699cdSAl Viro size_t chunk = min_t(size_t, n, PAGE_SIZE - off); 928893839fdSAl Viro char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page); 929893839fdSAl Viro memset(p + off, 0, chunk); 930893839fdSAl Viro kunmap_local(p); 9318cefc107SDavid Howells i->head = i_head; 932241699cdSAl Viro i->iov_offset = off + chunk; 933241699cdSAl Viro n -= chunk; 9348cefc107SDavid Howells off = 0; 9358cefc107SDavid Howells i_head++; 9368cefc107SDavid Howells } while (n); 937241699cdSAl Viro i->count -= bytes; 938241699cdSAl Viro return bytes; 939241699cdSAl Viro } 940241699cdSAl Viro 941d879cb83SAl Viro size_t iov_iter_zero(size_t bytes, struct iov_iter *i) 942d879cb83SAl Viro { 94300e23707SDavid Howells if (unlikely(iov_iter_is_pipe(i))) 944241699cdSAl Viro return pipe_zero(bytes, i); 9457baa5099SAl Viro iterate_and_advance(i, bytes, base, len, count, 9467baa5099SAl Viro clear_user(base, len), 9477baa5099SAl Viro memset(base, 0, len) 948d879cb83SAl Viro ) 949d879cb83SAl Viro 950d879cb83SAl Viro return bytes; 951d879cb83SAl Viro } 952d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_zero); 953d879cb83SAl Viro 954f0b65f39SAl Viro size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes, 955f0b65f39SAl Viro struct iov_iter *i) 956d879cb83SAl Viro { 957d879cb83SAl Viro char *kaddr = kmap_atomic(page), *p = kaddr + offset; 95872e809edSAl Viro if (unlikely(!page_copy_sane(page, offset, bytes))) { 95972e809edSAl Viro kunmap_atomic(kaddr); 96072e809edSAl Viro return 0; 96172e809edSAl Viro } 9629ea9ce04SDavid Howells if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 963241699cdSAl Viro kunmap_atomic(kaddr); 964241699cdSAl Viro WARN_ON(1); 965241699cdSAl Viro return 0; 966241699cdSAl Viro } 9677baa5099SAl Viro iterate_and_advance(i, bytes, base, len, off, 9687baa5099SAl Viro copyin(p + off, base, len), 9697baa5099SAl Viro memcpy(p + off, base, len) 970d879cb83SAl Viro ) 971d879cb83SAl Viro kunmap_atomic(kaddr); 972d879cb83SAl Viro return bytes; 973d879cb83SAl Viro } 974f0b65f39SAl Viro EXPORT_SYMBOL(copy_page_from_iter_atomic); 975d879cb83SAl Viro 976b9dc6f65SAl Viro static inline void pipe_truncate(struct iov_iter *i) 977241699cdSAl Viro { 978241699cdSAl Viro struct pipe_inode_info *pipe = i->pipe; 9798cefc107SDavid Howells unsigned int p_tail = pipe->tail; 9808cefc107SDavid Howells unsigned int p_head = pipe->head; 9818cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 9828cefc107SDavid Howells 9838cefc107SDavid Howells if (!pipe_empty(p_head, p_tail)) { 9848cefc107SDavid Howells struct pipe_buffer *buf; 9858cefc107SDavid Howells unsigned int i_head = i->head; 986b9dc6f65SAl Viro size_t off = i->iov_offset; 9878cefc107SDavid Howells 988b9dc6f65SAl Viro if (off) { 9898cefc107SDavid Howells buf = &pipe->bufs[i_head & p_mask]; 9908cefc107SDavid Howells buf->len = off - buf->offset; 9918cefc107SDavid Howells i_head++; 992b9dc6f65SAl Viro } 9938cefc107SDavid Howells while (p_head != i_head) { 9948cefc107SDavid Howells p_head--; 9958cefc107SDavid Howells pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]); 996241699cdSAl Viro } 9978cefc107SDavid Howells 9988cefc107SDavid Howells pipe->head = p_head; 999241699cdSAl Viro } 1000b9dc6f65SAl Viro } 1001b9dc6f65SAl Viro 1002b9dc6f65SAl Viro static void pipe_advance(struct iov_iter *i, size_t size) 1003b9dc6f65SAl Viro { 1004b9dc6f65SAl Viro struct pipe_inode_info *pipe = i->pipe; 1005b9dc6f65SAl Viro if (size) { 1006b9dc6f65SAl Viro struct pipe_buffer *buf; 10078cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 10088cefc107SDavid Howells unsigned int i_head = i->head; 1009b9dc6f65SAl Viro size_t off = i->iov_offset, left = size; 10108cefc107SDavid Howells 1011b9dc6f65SAl Viro if (off) /* make it relative to the beginning of buffer */ 10128cefc107SDavid Howells left += off - pipe->bufs[i_head & p_mask].offset; 1013b9dc6f65SAl Viro while (1) { 10148cefc107SDavid Howells buf = &pipe->bufs[i_head & p_mask]; 1015b9dc6f65SAl Viro if (left <= buf->len) 1016b9dc6f65SAl Viro break; 1017b9dc6f65SAl Viro left -= buf->len; 10188cefc107SDavid Howells i_head++; 1019b9dc6f65SAl Viro } 10208cefc107SDavid Howells i->head = i_head; 1021b9dc6f65SAl Viro i->iov_offset = buf->offset + left; 1022b9dc6f65SAl Viro } 1023b9dc6f65SAl Viro i->count -= size; 1024b9dc6f65SAl Viro /* ... and discard everything past that point */ 1025b9dc6f65SAl Viro pipe_truncate(i); 1026241699cdSAl Viro } 1027241699cdSAl Viro 102854c8195bSPavel Begunkov static void iov_iter_bvec_advance(struct iov_iter *i, size_t size) 102954c8195bSPavel Begunkov { 103054c8195bSPavel Begunkov struct bvec_iter bi; 103154c8195bSPavel Begunkov 103254c8195bSPavel Begunkov bi.bi_size = i->count; 103354c8195bSPavel Begunkov bi.bi_bvec_done = i->iov_offset; 103454c8195bSPavel Begunkov bi.bi_idx = 0; 103554c8195bSPavel Begunkov bvec_iter_advance(i->bvec, &bi, size); 103654c8195bSPavel Begunkov 103754c8195bSPavel Begunkov i->bvec += bi.bi_idx; 103854c8195bSPavel Begunkov i->nr_segs -= bi.bi_idx; 103954c8195bSPavel Begunkov i->count = bi.bi_size; 104054c8195bSPavel Begunkov i->iov_offset = bi.bi_bvec_done; 104154c8195bSPavel Begunkov } 104254c8195bSPavel Begunkov 1043185ac4d4SAl Viro static void iov_iter_iovec_advance(struct iov_iter *i, size_t size) 1044185ac4d4SAl Viro { 1045185ac4d4SAl Viro const struct iovec *iov, *end; 1046185ac4d4SAl Viro 1047185ac4d4SAl Viro if (!i->count) 1048185ac4d4SAl Viro return; 1049185ac4d4SAl Viro i->count -= size; 1050185ac4d4SAl Viro 1051185ac4d4SAl Viro size += i->iov_offset; // from beginning of current segment 1052185ac4d4SAl Viro for (iov = i->iov, end = iov + i->nr_segs; iov < end; iov++) { 1053185ac4d4SAl Viro if (likely(size < iov->iov_len)) 1054185ac4d4SAl Viro break; 1055185ac4d4SAl Viro size -= iov->iov_len; 1056185ac4d4SAl Viro } 1057185ac4d4SAl Viro i->iov_offset = size; 1058185ac4d4SAl Viro i->nr_segs -= iov - i->iov; 1059185ac4d4SAl Viro i->iov = iov; 1060185ac4d4SAl Viro } 1061185ac4d4SAl Viro 1062d879cb83SAl Viro void iov_iter_advance(struct iov_iter *i, size_t size) 1063d879cb83SAl Viro { 10643b3fc051SAl Viro if (unlikely(i->count < size)) 10653b3fc051SAl Viro size = i->count; 1066185ac4d4SAl Viro if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) { 1067185ac4d4SAl Viro /* iovec and kvec have identical layouts */ 1068185ac4d4SAl Viro iov_iter_iovec_advance(i, size); 1069185ac4d4SAl Viro } else if (iov_iter_is_bvec(i)) { 1070185ac4d4SAl Viro iov_iter_bvec_advance(i, size); 1071185ac4d4SAl Viro } else if (iov_iter_is_pipe(i)) { 1072241699cdSAl Viro pipe_advance(i, size); 1073185ac4d4SAl Viro } else if (unlikely(iov_iter_is_xarray(i))) { 10747ff50620SDavid Howells i->iov_offset += size; 10757ff50620SDavid Howells i->count -= size; 1076185ac4d4SAl Viro } else if (iov_iter_is_discard(i)) { 1077185ac4d4SAl Viro i->count -= size; 10787ff50620SDavid Howells } 1079d879cb83SAl Viro } 1080d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_advance); 1081d879cb83SAl Viro 108227c0e374SAl Viro void iov_iter_revert(struct iov_iter *i, size_t unroll) 108327c0e374SAl Viro { 108427c0e374SAl Viro if (!unroll) 108527c0e374SAl Viro return; 10865b47d59aSAl Viro if (WARN_ON(unroll > MAX_RW_COUNT)) 10875b47d59aSAl Viro return; 108827c0e374SAl Viro i->count += unroll; 108900e23707SDavid Howells if (unlikely(iov_iter_is_pipe(i))) { 109027c0e374SAl Viro struct pipe_inode_info *pipe = i->pipe; 10918cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 10928cefc107SDavid Howells unsigned int i_head = i->head; 109327c0e374SAl Viro size_t off = i->iov_offset; 109427c0e374SAl Viro while (1) { 10958cefc107SDavid Howells struct pipe_buffer *b = &pipe->bufs[i_head & p_mask]; 10968cefc107SDavid Howells size_t n = off - b->offset; 109727c0e374SAl Viro if (unroll < n) { 10984fa55cefSAl Viro off -= unroll; 109927c0e374SAl Viro break; 110027c0e374SAl Viro } 110127c0e374SAl Viro unroll -= n; 11028cefc107SDavid Howells if (!unroll && i_head == i->start_head) { 110327c0e374SAl Viro off = 0; 110427c0e374SAl Viro break; 110527c0e374SAl Viro } 11068cefc107SDavid Howells i_head--; 11078cefc107SDavid Howells b = &pipe->bufs[i_head & p_mask]; 11088cefc107SDavid Howells off = b->offset + b->len; 110927c0e374SAl Viro } 111027c0e374SAl Viro i->iov_offset = off; 11118cefc107SDavid Howells i->head = i_head; 111227c0e374SAl Viro pipe_truncate(i); 111327c0e374SAl Viro return; 111427c0e374SAl Viro } 11159ea9ce04SDavid Howells if (unlikely(iov_iter_is_discard(i))) 11169ea9ce04SDavid Howells return; 111727c0e374SAl Viro if (unroll <= i->iov_offset) { 111827c0e374SAl Viro i->iov_offset -= unroll; 111927c0e374SAl Viro return; 112027c0e374SAl Viro } 112127c0e374SAl Viro unroll -= i->iov_offset; 11227ff50620SDavid Howells if (iov_iter_is_xarray(i)) { 11237ff50620SDavid Howells BUG(); /* We should never go beyond the start of the specified 11247ff50620SDavid Howells * range since we might then be straying into pages that 11257ff50620SDavid Howells * aren't pinned. 11267ff50620SDavid Howells */ 11277ff50620SDavid Howells } else if (iov_iter_is_bvec(i)) { 112827c0e374SAl Viro const struct bio_vec *bvec = i->bvec; 112927c0e374SAl Viro while (1) { 113027c0e374SAl Viro size_t n = (--bvec)->bv_len; 113127c0e374SAl Viro i->nr_segs++; 113227c0e374SAl Viro if (unroll <= n) { 113327c0e374SAl Viro i->bvec = bvec; 113427c0e374SAl Viro i->iov_offset = n - unroll; 113527c0e374SAl Viro return; 113627c0e374SAl Viro } 113727c0e374SAl Viro unroll -= n; 113827c0e374SAl Viro } 113927c0e374SAl Viro } else { /* same logics for iovec and kvec */ 114027c0e374SAl Viro const struct iovec *iov = i->iov; 114127c0e374SAl Viro while (1) { 114227c0e374SAl Viro size_t n = (--iov)->iov_len; 114327c0e374SAl Viro i->nr_segs++; 114427c0e374SAl Viro if (unroll <= n) { 114527c0e374SAl Viro i->iov = iov; 114627c0e374SAl Viro i->iov_offset = n - unroll; 114727c0e374SAl Viro return; 114827c0e374SAl Viro } 114927c0e374SAl Viro unroll -= n; 115027c0e374SAl Viro } 115127c0e374SAl Viro } 115227c0e374SAl Viro } 115327c0e374SAl Viro EXPORT_SYMBOL(iov_iter_revert); 115427c0e374SAl Viro 1155d879cb83SAl Viro /* 1156d879cb83SAl Viro * Return the count of just the current iov_iter segment. 1157d879cb83SAl Viro */ 1158d879cb83SAl Viro size_t iov_iter_single_seg_count(const struct iov_iter *i) 1159d879cb83SAl Viro { 116028f38db7SAl Viro if (i->nr_segs > 1) { 116128f38db7SAl Viro if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) 116228f38db7SAl Viro return min(i->count, i->iov->iov_len - i->iov_offset); 11637ff50620SDavid Howells if (iov_iter_is_bvec(i)) 1164d879cb83SAl Viro return min(i->count, i->bvec->bv_len - i->iov_offset); 116528f38db7SAl Viro } 116628f38db7SAl Viro return i->count; 1167d879cb83SAl Viro } 1168d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_single_seg_count); 1169d879cb83SAl Viro 1170aa563d7bSDavid Howells void iov_iter_kvec(struct iov_iter *i, unsigned int direction, 1171d879cb83SAl Viro const struct kvec *kvec, unsigned long nr_segs, 1172d879cb83SAl Viro size_t count) 1173d879cb83SAl Viro { 1174aa563d7bSDavid Howells WARN_ON(direction & ~(READ | WRITE)); 11758cd54c1cSAl Viro *i = (struct iov_iter){ 11768cd54c1cSAl Viro .iter_type = ITER_KVEC, 11778cd54c1cSAl Viro .data_source = direction, 11788cd54c1cSAl Viro .kvec = kvec, 11798cd54c1cSAl Viro .nr_segs = nr_segs, 11808cd54c1cSAl Viro .iov_offset = 0, 11818cd54c1cSAl Viro .count = count 11828cd54c1cSAl Viro }; 1183d879cb83SAl Viro } 1184d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_kvec); 1185d879cb83SAl Viro 1186aa563d7bSDavid Howells void iov_iter_bvec(struct iov_iter *i, unsigned int direction, 1187d879cb83SAl Viro const struct bio_vec *bvec, unsigned long nr_segs, 1188d879cb83SAl Viro size_t count) 1189d879cb83SAl Viro { 1190aa563d7bSDavid Howells WARN_ON(direction & ~(READ | WRITE)); 11918cd54c1cSAl Viro *i = (struct iov_iter){ 11928cd54c1cSAl Viro .iter_type = ITER_BVEC, 11938cd54c1cSAl Viro .data_source = direction, 11948cd54c1cSAl Viro .bvec = bvec, 11958cd54c1cSAl Viro .nr_segs = nr_segs, 11968cd54c1cSAl Viro .iov_offset = 0, 11978cd54c1cSAl Viro .count = count 11988cd54c1cSAl Viro }; 1199d879cb83SAl Viro } 1200d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_bvec); 1201d879cb83SAl Viro 1202aa563d7bSDavid Howells void iov_iter_pipe(struct iov_iter *i, unsigned int direction, 1203241699cdSAl Viro struct pipe_inode_info *pipe, 1204241699cdSAl Viro size_t count) 1205241699cdSAl Viro { 1206aa563d7bSDavid Howells BUG_ON(direction != READ); 12078cefc107SDavid Howells WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size)); 12088cd54c1cSAl Viro *i = (struct iov_iter){ 12098cd54c1cSAl Viro .iter_type = ITER_PIPE, 12108cd54c1cSAl Viro .data_source = false, 12118cd54c1cSAl Viro .pipe = pipe, 12128cd54c1cSAl Viro .head = pipe->head, 12138cd54c1cSAl Viro .start_head = pipe->head, 12148cd54c1cSAl Viro .iov_offset = 0, 12158cd54c1cSAl Viro .count = count 12168cd54c1cSAl Viro }; 1217241699cdSAl Viro } 1218241699cdSAl Viro EXPORT_SYMBOL(iov_iter_pipe); 1219241699cdSAl Viro 12209ea9ce04SDavid Howells /** 12217ff50620SDavid Howells * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray 12227ff50620SDavid Howells * @i: The iterator to initialise. 12237ff50620SDavid Howells * @direction: The direction of the transfer. 12247ff50620SDavid Howells * @xarray: The xarray to access. 12257ff50620SDavid Howells * @start: The start file position. 12267ff50620SDavid Howells * @count: The size of the I/O buffer in bytes. 12277ff50620SDavid Howells * 12287ff50620SDavid Howells * Set up an I/O iterator to either draw data out of the pages attached to an 12297ff50620SDavid Howells * inode or to inject data into those pages. The pages *must* be prevented 12307ff50620SDavid Howells * from evaporation, either by taking a ref on them or locking them by the 12317ff50620SDavid Howells * caller. 12327ff50620SDavid Howells */ 12337ff50620SDavid Howells void iov_iter_xarray(struct iov_iter *i, unsigned int direction, 12347ff50620SDavid Howells struct xarray *xarray, loff_t start, size_t count) 12357ff50620SDavid Howells { 12367ff50620SDavid Howells BUG_ON(direction & ~1); 12378cd54c1cSAl Viro *i = (struct iov_iter) { 12388cd54c1cSAl Viro .iter_type = ITER_XARRAY, 12398cd54c1cSAl Viro .data_source = direction, 12408cd54c1cSAl Viro .xarray = xarray, 12418cd54c1cSAl Viro .xarray_start = start, 12428cd54c1cSAl Viro .count = count, 12438cd54c1cSAl Viro .iov_offset = 0 12448cd54c1cSAl Viro }; 12457ff50620SDavid Howells } 12467ff50620SDavid Howells EXPORT_SYMBOL(iov_iter_xarray); 12477ff50620SDavid Howells 12487ff50620SDavid Howells /** 12499ea9ce04SDavid Howells * iov_iter_discard - Initialise an I/O iterator that discards data 12509ea9ce04SDavid Howells * @i: The iterator to initialise. 12519ea9ce04SDavid Howells * @direction: The direction of the transfer. 12529ea9ce04SDavid Howells * @count: The size of the I/O buffer in bytes. 12539ea9ce04SDavid Howells * 12549ea9ce04SDavid Howells * Set up an I/O iterator that just discards everything that's written to it. 12559ea9ce04SDavid Howells * It's only available as a READ iterator. 12569ea9ce04SDavid Howells */ 12579ea9ce04SDavid Howells void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count) 12589ea9ce04SDavid Howells { 12599ea9ce04SDavid Howells BUG_ON(direction != READ); 12608cd54c1cSAl Viro *i = (struct iov_iter){ 12618cd54c1cSAl Viro .iter_type = ITER_DISCARD, 12628cd54c1cSAl Viro .data_source = false, 12638cd54c1cSAl Viro .count = count, 12648cd54c1cSAl Viro .iov_offset = 0 12658cd54c1cSAl Viro }; 12669ea9ce04SDavid Howells } 12679ea9ce04SDavid Howells EXPORT_SYMBOL(iov_iter_discard); 12689ea9ce04SDavid Howells 12699221d2e3SAl Viro static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i) 1270d879cb83SAl Viro { 1271d879cb83SAl Viro unsigned long res = 0; 1272d879cb83SAl Viro size_t size = i->count; 12739221d2e3SAl Viro size_t skip = i->iov_offset; 12749221d2e3SAl Viro unsigned k; 1275d879cb83SAl Viro 12769221d2e3SAl Viro for (k = 0; k < i->nr_segs; k++, skip = 0) { 12779221d2e3SAl Viro size_t len = i->iov[k].iov_len - skip; 12789221d2e3SAl Viro if (len) { 12799221d2e3SAl Viro res |= (unsigned long)i->iov[k].iov_base + skip; 12809221d2e3SAl Viro if (len > size) 12819221d2e3SAl Viro len = size; 12829221d2e3SAl Viro res |= len; 12839221d2e3SAl Viro size -= len; 12849221d2e3SAl Viro if (!size) 12859221d2e3SAl Viro break; 12869221d2e3SAl Viro } 12879221d2e3SAl Viro } 12889221d2e3SAl Viro return res; 12899221d2e3SAl Viro } 12909221d2e3SAl Viro 12919221d2e3SAl Viro static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i) 12929221d2e3SAl Viro { 12939221d2e3SAl Viro unsigned res = 0; 12949221d2e3SAl Viro size_t size = i->count; 12959221d2e3SAl Viro unsigned skip = i->iov_offset; 12969221d2e3SAl Viro unsigned k; 12979221d2e3SAl Viro 12989221d2e3SAl Viro for (k = 0; k < i->nr_segs; k++, skip = 0) { 12999221d2e3SAl Viro size_t len = i->bvec[k].bv_len - skip; 13009221d2e3SAl Viro res |= (unsigned long)i->bvec[k].bv_offset + skip; 13019221d2e3SAl Viro if (len > size) 13029221d2e3SAl Viro len = size; 13039221d2e3SAl Viro res |= len; 13049221d2e3SAl Viro size -= len; 13059221d2e3SAl Viro if (!size) 13069221d2e3SAl Viro break; 13079221d2e3SAl Viro } 13089221d2e3SAl Viro return res; 13099221d2e3SAl Viro } 13109221d2e3SAl Viro 13119221d2e3SAl Viro unsigned long iov_iter_alignment(const struct iov_iter *i) 13129221d2e3SAl Viro { 13139221d2e3SAl Viro /* iovec and kvec have identical layouts */ 13149221d2e3SAl Viro if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) 13159221d2e3SAl Viro return iov_iter_alignment_iovec(i); 13169221d2e3SAl Viro 13179221d2e3SAl Viro if (iov_iter_is_bvec(i)) 13189221d2e3SAl Viro return iov_iter_alignment_bvec(i); 13199221d2e3SAl Viro 13209221d2e3SAl Viro if (iov_iter_is_pipe(i)) { 1321e0ff126eSJan Kara unsigned int p_mask = i->pipe->ring_size - 1; 13229221d2e3SAl Viro size_t size = i->count; 1323e0ff126eSJan Kara 13248cefc107SDavid Howells if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask])) 1325241699cdSAl Viro return size | i->iov_offset; 1326241699cdSAl Viro return size; 1327241699cdSAl Viro } 13289221d2e3SAl Viro 13299221d2e3SAl Viro if (iov_iter_is_xarray(i)) 13303d14ec1fSDavid Howells return (i->xarray_start + i->iov_offset) | i->count; 13319221d2e3SAl Viro 13329221d2e3SAl Viro return 0; 1333d879cb83SAl Viro } 1334d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_alignment); 1335d879cb83SAl Viro 1336357f435dSAl Viro unsigned long iov_iter_gap_alignment(const struct iov_iter *i) 1337357f435dSAl Viro { 1338357f435dSAl Viro unsigned long res = 0; 1339610c7a71SAl Viro unsigned long v = 0; 1340357f435dSAl Viro size_t size = i->count; 1341610c7a71SAl Viro unsigned k; 1342357f435dSAl Viro 1343610c7a71SAl Viro if (WARN_ON(!iter_is_iovec(i))) 1344241699cdSAl Viro return ~0U; 1345241699cdSAl Viro 1346610c7a71SAl Viro for (k = 0; k < i->nr_segs; k++) { 1347610c7a71SAl Viro if (i->iov[k].iov_len) { 1348610c7a71SAl Viro unsigned long base = (unsigned long)i->iov[k].iov_base; 1349610c7a71SAl Viro if (v) // if not the first one 1350610c7a71SAl Viro res |= base | v; // this start | previous end 1351610c7a71SAl Viro v = base + i->iov[k].iov_len; 1352610c7a71SAl Viro if (size <= i->iov[k].iov_len) 1353610c7a71SAl Viro break; 1354610c7a71SAl Viro size -= i->iov[k].iov_len; 1355610c7a71SAl Viro } 1356610c7a71SAl Viro } 1357357f435dSAl Viro return res; 1358357f435dSAl Viro } 1359357f435dSAl Viro EXPORT_SYMBOL(iov_iter_gap_alignment); 1360357f435dSAl Viro 1361e76b6312SIlya Dryomov static inline ssize_t __pipe_get_pages(struct iov_iter *i, 1362241699cdSAl Viro size_t maxsize, 1363241699cdSAl Viro struct page **pages, 13648cefc107SDavid Howells int iter_head, 1365241699cdSAl Viro size_t *start) 1366241699cdSAl Viro { 1367241699cdSAl Viro struct pipe_inode_info *pipe = i->pipe; 13688cefc107SDavid Howells unsigned int p_mask = pipe->ring_size - 1; 13698cefc107SDavid Howells ssize_t n = push_pipe(i, maxsize, &iter_head, start); 1370241699cdSAl Viro if (!n) 1371241699cdSAl Viro return -EFAULT; 1372241699cdSAl Viro 1373241699cdSAl Viro maxsize = n; 1374241699cdSAl Viro n += *start; 13751689c73aSAl Viro while (n > 0) { 13768cefc107SDavid Howells get_page(*pages++ = pipe->bufs[iter_head & p_mask].page); 13778cefc107SDavid Howells iter_head++; 1378241699cdSAl Viro n -= PAGE_SIZE; 1379241699cdSAl Viro } 1380241699cdSAl Viro 1381241699cdSAl Viro return maxsize; 1382241699cdSAl Viro } 1383241699cdSAl Viro 1384241699cdSAl Viro static ssize_t pipe_get_pages(struct iov_iter *i, 1385241699cdSAl Viro struct page **pages, size_t maxsize, unsigned maxpages, 1386241699cdSAl Viro size_t *start) 1387241699cdSAl Viro { 13888cefc107SDavid Howells unsigned int iter_head, npages; 1389241699cdSAl Viro size_t capacity; 1390241699cdSAl Viro 1391241699cdSAl Viro if (!sanity(i)) 1392241699cdSAl Viro return -EFAULT; 1393241699cdSAl Viro 13948cefc107SDavid Howells data_start(i, &iter_head, start); 13958cefc107SDavid Howells /* Amount of free space: some of this one + all after this one */ 13968cefc107SDavid Howells npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1397241699cdSAl Viro capacity = min(npages, maxpages) * PAGE_SIZE - *start; 1398241699cdSAl Viro 13998cefc107SDavid Howells return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start); 1400241699cdSAl Viro } 1401241699cdSAl Viro 14027ff50620SDavid Howells static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, 14037ff50620SDavid Howells pgoff_t index, unsigned int nr_pages) 14047ff50620SDavid Howells { 14057ff50620SDavid Howells XA_STATE(xas, xa, index); 14067ff50620SDavid Howells struct page *page; 14077ff50620SDavid Howells unsigned int ret = 0; 14087ff50620SDavid Howells 14097ff50620SDavid Howells rcu_read_lock(); 14107ff50620SDavid Howells for (page = xas_load(&xas); page; page = xas_next(&xas)) { 14117ff50620SDavid Howells if (xas_retry(&xas, page)) 14127ff50620SDavid Howells continue; 14137ff50620SDavid Howells 14147ff50620SDavid Howells /* Has the page moved or been split? */ 14157ff50620SDavid Howells if (unlikely(page != xas_reload(&xas))) { 14167ff50620SDavid Howells xas_reset(&xas); 14177ff50620SDavid Howells continue; 14187ff50620SDavid Howells } 14197ff50620SDavid Howells 14207ff50620SDavid Howells pages[ret] = find_subpage(page, xas.xa_index); 14217ff50620SDavid Howells get_page(pages[ret]); 14227ff50620SDavid Howells if (++ret == nr_pages) 14237ff50620SDavid Howells break; 14247ff50620SDavid Howells } 14257ff50620SDavid Howells rcu_read_unlock(); 14267ff50620SDavid Howells return ret; 14277ff50620SDavid Howells } 14287ff50620SDavid Howells 14297ff50620SDavid Howells static ssize_t iter_xarray_get_pages(struct iov_iter *i, 14307ff50620SDavid Howells struct page **pages, size_t maxsize, 14317ff50620SDavid Howells unsigned maxpages, size_t *_start_offset) 14327ff50620SDavid Howells { 14337ff50620SDavid Howells unsigned nr, offset; 14347ff50620SDavid Howells pgoff_t index, count; 14357ff50620SDavid Howells size_t size = maxsize, actual; 14367ff50620SDavid Howells loff_t pos; 14377ff50620SDavid Howells 14387ff50620SDavid Howells if (!size || !maxpages) 14397ff50620SDavid Howells return 0; 14407ff50620SDavid Howells 14417ff50620SDavid Howells pos = i->xarray_start + i->iov_offset; 14427ff50620SDavid Howells index = pos >> PAGE_SHIFT; 14437ff50620SDavid Howells offset = pos & ~PAGE_MASK; 14447ff50620SDavid Howells *_start_offset = offset; 14457ff50620SDavid Howells 14467ff50620SDavid Howells count = 1; 14477ff50620SDavid Howells if (size > PAGE_SIZE - offset) { 14487ff50620SDavid Howells size -= PAGE_SIZE - offset; 14497ff50620SDavid Howells count += size >> PAGE_SHIFT; 14507ff50620SDavid Howells size &= ~PAGE_MASK; 14517ff50620SDavid Howells if (size) 14527ff50620SDavid Howells count++; 14537ff50620SDavid Howells } 14547ff50620SDavid Howells 14557ff50620SDavid Howells if (count > maxpages) 14567ff50620SDavid Howells count = maxpages; 14577ff50620SDavid Howells 14587ff50620SDavid Howells nr = iter_xarray_populate_pages(pages, i->xarray, index, count); 14597ff50620SDavid Howells if (nr == 0) 14607ff50620SDavid Howells return 0; 14617ff50620SDavid Howells 14627ff50620SDavid Howells actual = PAGE_SIZE * nr; 14637ff50620SDavid Howells actual -= offset; 14647ff50620SDavid Howells if (nr == count && size > 0) { 14657ff50620SDavid Howells unsigned last_offset = (nr > 1) ? 0 : offset; 14667ff50620SDavid Howells actual -= PAGE_SIZE - (last_offset + size); 14677ff50620SDavid Howells } 14687ff50620SDavid Howells return actual; 14697ff50620SDavid Howells } 14707ff50620SDavid Howells 14713d671ca6SAl Viro /* must be done on non-empty ITER_IOVEC one */ 14723d671ca6SAl Viro static unsigned long first_iovec_segment(const struct iov_iter *i, 14733d671ca6SAl Viro size_t *size, size_t *start, 14743d671ca6SAl Viro size_t maxsize, unsigned maxpages) 14753d671ca6SAl Viro { 14763d671ca6SAl Viro size_t skip; 14773d671ca6SAl Viro long k; 14783d671ca6SAl Viro 14793d671ca6SAl Viro for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) { 14803d671ca6SAl Viro unsigned long addr = (unsigned long)i->iov[k].iov_base + skip; 14813d671ca6SAl Viro size_t len = i->iov[k].iov_len - skip; 14823d671ca6SAl Viro 14833d671ca6SAl Viro if (unlikely(!len)) 14843d671ca6SAl Viro continue; 14853d671ca6SAl Viro if (len > maxsize) 14863d671ca6SAl Viro len = maxsize; 14873d671ca6SAl Viro len += (*start = addr % PAGE_SIZE); 14883d671ca6SAl Viro if (len > maxpages * PAGE_SIZE) 14893d671ca6SAl Viro len = maxpages * PAGE_SIZE; 14903d671ca6SAl Viro *size = len; 14913d671ca6SAl Viro return addr & PAGE_MASK; 14923d671ca6SAl Viro } 14933d671ca6SAl Viro BUG(); // if it had been empty, we wouldn't get called 14943d671ca6SAl Viro } 14953d671ca6SAl Viro 14963d671ca6SAl Viro /* must be done on non-empty ITER_BVEC one */ 14973d671ca6SAl Viro static struct page *first_bvec_segment(const struct iov_iter *i, 14983d671ca6SAl Viro size_t *size, size_t *start, 14993d671ca6SAl Viro size_t maxsize, unsigned maxpages) 15003d671ca6SAl Viro { 15013d671ca6SAl Viro struct page *page; 15023d671ca6SAl Viro size_t skip = i->iov_offset, len; 15033d671ca6SAl Viro 15043d671ca6SAl Viro len = i->bvec->bv_len - skip; 15053d671ca6SAl Viro if (len > maxsize) 15063d671ca6SAl Viro len = maxsize; 15073d671ca6SAl Viro skip += i->bvec->bv_offset; 15083d671ca6SAl Viro page = i->bvec->bv_page + skip / PAGE_SIZE; 15093d671ca6SAl Viro len += (*start = skip % PAGE_SIZE); 15103d671ca6SAl Viro if (len > maxpages * PAGE_SIZE) 15113d671ca6SAl Viro len = maxpages * PAGE_SIZE; 15123d671ca6SAl Viro *size = len; 15133d671ca6SAl Viro return page; 15143d671ca6SAl Viro } 15153d671ca6SAl Viro 1516d879cb83SAl Viro ssize_t iov_iter_get_pages(struct iov_iter *i, 1517d879cb83SAl Viro struct page **pages, size_t maxsize, unsigned maxpages, 1518d879cb83SAl Viro size_t *start) 1519d879cb83SAl Viro { 15203d671ca6SAl Viro size_t len; 15213d671ca6SAl Viro int n, res; 15223d671ca6SAl Viro 1523d879cb83SAl Viro if (maxsize > i->count) 1524d879cb83SAl Viro maxsize = i->count; 15253d671ca6SAl Viro if (!maxsize) 15263d671ca6SAl Viro return 0; 1527d879cb83SAl Viro 15283d671ca6SAl Viro if (likely(iter_is_iovec(i))) { 15293337ab08SAndreas Gruenbacher unsigned int gup_flags = 0; 15303d671ca6SAl Viro unsigned long addr; 15319ea9ce04SDavid Howells 15323337ab08SAndreas Gruenbacher if (iov_iter_rw(i) != WRITE) 15333337ab08SAndreas Gruenbacher gup_flags |= FOLL_WRITE; 15343337ab08SAndreas Gruenbacher if (i->nofault) 15353337ab08SAndreas Gruenbacher gup_flags |= FOLL_NOFAULT; 15363337ab08SAndreas Gruenbacher 15373d671ca6SAl Viro addr = first_iovec_segment(i, &len, start, maxsize, maxpages); 1538d879cb83SAl Viro n = DIV_ROUND_UP(len, PAGE_SIZE); 15393337ab08SAndreas Gruenbacher res = get_user_pages_fast(addr, n, gup_flags, pages); 1540814a6674SAndreas Gruenbacher if (unlikely(res <= 0)) 1541d879cb83SAl Viro return res; 1542d879cb83SAl Viro return (res == n ? len : res * PAGE_SIZE) - *start; 15433d671ca6SAl Viro } 15443d671ca6SAl Viro if (iov_iter_is_bvec(i)) { 15453d671ca6SAl Viro struct page *page; 15463d671ca6SAl Viro 15473d671ca6SAl Viro page = first_bvec_segment(i, &len, start, maxsize, maxpages); 15483d671ca6SAl Viro n = DIV_ROUND_UP(len, PAGE_SIZE); 15493d671ca6SAl Viro while (n--) 15503d671ca6SAl Viro get_page(*pages++ = page++); 15513d671ca6SAl Viro return len - *start; 15523d671ca6SAl Viro } 15533d671ca6SAl Viro if (iov_iter_is_pipe(i)) 15543d671ca6SAl Viro return pipe_get_pages(i, pages, maxsize, maxpages, start); 15553d671ca6SAl Viro if (iov_iter_is_xarray(i)) 15563d671ca6SAl Viro return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); 1557d879cb83SAl Viro return -EFAULT; 1558d879cb83SAl Viro } 1559d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_get_pages); 1560d879cb83SAl Viro 1561d879cb83SAl Viro static struct page **get_pages_array(size_t n) 1562d879cb83SAl Viro { 1563752ade68SMichal Hocko return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); 1564d879cb83SAl Viro } 1565d879cb83SAl Viro 1566241699cdSAl Viro static ssize_t pipe_get_pages_alloc(struct iov_iter *i, 1567241699cdSAl Viro struct page ***pages, size_t maxsize, 1568241699cdSAl Viro size_t *start) 1569241699cdSAl Viro { 1570241699cdSAl Viro struct page **p; 15718cefc107SDavid Howells unsigned int iter_head, npages; 1572d7760d63SIlya Dryomov ssize_t n; 1573241699cdSAl Viro 1574241699cdSAl Viro if (!sanity(i)) 1575241699cdSAl Viro return -EFAULT; 1576241699cdSAl Viro 15778cefc107SDavid Howells data_start(i, &iter_head, start); 15788cefc107SDavid Howells /* Amount of free space: some of this one + all after this one */ 15798cefc107SDavid Howells npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 1580241699cdSAl Viro n = npages * PAGE_SIZE - *start; 1581241699cdSAl Viro if (maxsize > n) 1582241699cdSAl Viro maxsize = n; 1583241699cdSAl Viro else 1584241699cdSAl Viro npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE); 1585241699cdSAl Viro p = get_pages_array(npages); 1586241699cdSAl Viro if (!p) 1587241699cdSAl Viro return -ENOMEM; 15888cefc107SDavid Howells n = __pipe_get_pages(i, maxsize, p, iter_head, start); 1589241699cdSAl Viro if (n > 0) 1590241699cdSAl Viro *pages = p; 1591241699cdSAl Viro else 1592241699cdSAl Viro kvfree(p); 1593241699cdSAl Viro return n; 1594241699cdSAl Viro } 1595241699cdSAl Viro 15967ff50620SDavid Howells static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i, 15977ff50620SDavid Howells struct page ***pages, size_t maxsize, 15987ff50620SDavid Howells size_t *_start_offset) 15997ff50620SDavid Howells { 16007ff50620SDavid Howells struct page **p; 16017ff50620SDavid Howells unsigned nr, offset; 16027ff50620SDavid Howells pgoff_t index, count; 16037ff50620SDavid Howells size_t size = maxsize, actual; 16047ff50620SDavid Howells loff_t pos; 16057ff50620SDavid Howells 16067ff50620SDavid Howells if (!size) 16077ff50620SDavid Howells return 0; 16087ff50620SDavid Howells 16097ff50620SDavid Howells pos = i->xarray_start + i->iov_offset; 16107ff50620SDavid Howells index = pos >> PAGE_SHIFT; 16117ff50620SDavid Howells offset = pos & ~PAGE_MASK; 16127ff50620SDavid Howells *_start_offset = offset; 16137ff50620SDavid Howells 16147ff50620SDavid Howells count = 1; 16157ff50620SDavid Howells if (size > PAGE_SIZE - offset) { 16167ff50620SDavid Howells size -= PAGE_SIZE - offset; 16177ff50620SDavid Howells count += size >> PAGE_SHIFT; 16187ff50620SDavid Howells size &= ~PAGE_MASK; 16197ff50620SDavid Howells if (size) 16207ff50620SDavid Howells count++; 16217ff50620SDavid Howells } 16227ff50620SDavid Howells 16237ff50620SDavid Howells p = get_pages_array(count); 16247ff50620SDavid Howells if (!p) 16257ff50620SDavid Howells return -ENOMEM; 16267ff50620SDavid Howells *pages = p; 16277ff50620SDavid Howells 16287ff50620SDavid Howells nr = iter_xarray_populate_pages(p, i->xarray, index, count); 16297ff50620SDavid Howells if (nr == 0) 16307ff50620SDavid Howells return 0; 16317ff50620SDavid Howells 16327ff50620SDavid Howells actual = PAGE_SIZE * nr; 16337ff50620SDavid Howells actual -= offset; 16347ff50620SDavid Howells if (nr == count && size > 0) { 16357ff50620SDavid Howells unsigned last_offset = (nr > 1) ? 0 : offset; 16367ff50620SDavid Howells actual -= PAGE_SIZE - (last_offset + size); 16377ff50620SDavid Howells } 16387ff50620SDavid Howells return actual; 16397ff50620SDavid Howells } 16407ff50620SDavid Howells 1641d879cb83SAl Viro ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, 1642d879cb83SAl Viro struct page ***pages, size_t maxsize, 1643d879cb83SAl Viro size_t *start) 1644d879cb83SAl Viro { 1645d879cb83SAl Viro struct page **p; 16463d671ca6SAl Viro size_t len; 16473d671ca6SAl Viro int n, res; 1648d879cb83SAl Viro 1649d879cb83SAl Viro if (maxsize > i->count) 1650d879cb83SAl Viro maxsize = i->count; 16513d671ca6SAl Viro if (!maxsize) 16523d671ca6SAl Viro return 0; 1653d879cb83SAl Viro 16543d671ca6SAl Viro if (likely(iter_is_iovec(i))) { 16553337ab08SAndreas Gruenbacher unsigned int gup_flags = 0; 16563d671ca6SAl Viro unsigned long addr; 16579ea9ce04SDavid Howells 16583337ab08SAndreas Gruenbacher if (iov_iter_rw(i) != WRITE) 16593337ab08SAndreas Gruenbacher gup_flags |= FOLL_WRITE; 16603337ab08SAndreas Gruenbacher if (i->nofault) 16613337ab08SAndreas Gruenbacher gup_flags |= FOLL_NOFAULT; 16623337ab08SAndreas Gruenbacher 16633d671ca6SAl Viro addr = first_iovec_segment(i, &len, start, maxsize, ~0U); 1664d879cb83SAl Viro n = DIV_ROUND_UP(len, PAGE_SIZE); 1665d879cb83SAl Viro p = get_pages_array(n); 1666d879cb83SAl Viro if (!p) 1667d879cb83SAl Viro return -ENOMEM; 16683337ab08SAndreas Gruenbacher res = get_user_pages_fast(addr, n, gup_flags, p); 1669814a6674SAndreas Gruenbacher if (unlikely(res <= 0)) { 1670d879cb83SAl Viro kvfree(p); 1671814a6674SAndreas Gruenbacher *pages = NULL; 1672d879cb83SAl Viro return res; 1673d879cb83SAl Viro } 1674d879cb83SAl Viro *pages = p; 1675d879cb83SAl Viro return (res == n ? len : res * PAGE_SIZE) - *start; 16763d671ca6SAl Viro } 16773d671ca6SAl Viro if (iov_iter_is_bvec(i)) { 16783d671ca6SAl Viro struct page *page; 16793d671ca6SAl Viro 16803d671ca6SAl Viro page = first_bvec_segment(i, &len, start, maxsize, ~0U); 16813d671ca6SAl Viro n = DIV_ROUND_UP(len, PAGE_SIZE); 16823d671ca6SAl Viro *pages = p = get_pages_array(n); 1683d879cb83SAl Viro if (!p) 1684d879cb83SAl Viro return -ENOMEM; 16853d671ca6SAl Viro while (n--) 16863d671ca6SAl Viro get_page(*p++ = page++); 16873d671ca6SAl Viro return len - *start; 16883d671ca6SAl Viro } 16893d671ca6SAl Viro if (iov_iter_is_pipe(i)) 16903d671ca6SAl Viro return pipe_get_pages_alloc(i, pages, maxsize, start); 16913d671ca6SAl Viro if (iov_iter_is_xarray(i)) 16923d671ca6SAl Viro return iter_xarray_get_pages_alloc(i, pages, maxsize, start); 1693d879cb83SAl Viro return -EFAULT; 1694d879cb83SAl Viro } 1695d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_get_pages_alloc); 1696d879cb83SAl Viro 1697d879cb83SAl Viro size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, 1698d879cb83SAl Viro struct iov_iter *i) 1699d879cb83SAl Viro { 1700d879cb83SAl Viro __wsum sum, next; 1701d879cb83SAl Viro sum = *csum; 17029ea9ce04SDavid Howells if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) { 1703241699cdSAl Viro WARN_ON(1); 1704241699cdSAl Viro return 0; 1705241699cdSAl Viro } 17067baa5099SAl Viro iterate_and_advance(i, bytes, base, len, off, ({ 17077baa5099SAl Viro next = csum_and_copy_from_user(base, addr + off, len); 1708d879cb83SAl Viro sum = csum_block_add(sum, next, off); 17097baa5099SAl Viro next ? 0 : len; 1710d879cb83SAl Viro }), ({ 17117baa5099SAl Viro sum = csum_and_memcpy(addr + off, base, len, sum, off); 1712d879cb83SAl Viro }) 1713d879cb83SAl Viro ) 1714d879cb83SAl Viro *csum = sum; 1715d879cb83SAl Viro return bytes; 1716d879cb83SAl Viro } 1717d879cb83SAl Viro EXPORT_SYMBOL(csum_and_copy_from_iter); 1718d879cb83SAl Viro 171952cbd23aSWillem de Bruijn size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate, 1720d879cb83SAl Viro struct iov_iter *i) 1721d879cb83SAl Viro { 172252cbd23aSWillem de Bruijn struct csum_state *csstate = _csstate; 1723d879cb83SAl Viro __wsum sum, next; 172478e1f386SAl Viro 172578e1f386SAl Viro if (unlikely(iov_iter_is_discard(i))) { 1726241699cdSAl Viro WARN_ON(1); /* for now */ 1727241699cdSAl Viro return 0; 1728241699cdSAl Viro } 17296852df12SAl Viro 17306852df12SAl Viro sum = csum_shift(csstate->csum, csstate->off); 17316852df12SAl Viro if (unlikely(iov_iter_is_pipe(i))) 17326852df12SAl Viro bytes = csum_and_copy_to_pipe_iter(addr, bytes, i, &sum); 17336852df12SAl Viro else iterate_and_advance(i, bytes, base, len, off, ({ 17347baa5099SAl Viro next = csum_and_copy_to_user(addr + off, base, len); 1735d879cb83SAl Viro sum = csum_block_add(sum, next, off); 17367baa5099SAl Viro next ? 0 : len; 1737d879cb83SAl Viro }), ({ 17387baa5099SAl Viro sum = csum_and_memcpy(base, addr + off, len, sum, off); 1739d879cb83SAl Viro }) 1740d879cb83SAl Viro ) 1741594e450bSAl Viro csstate->csum = csum_shift(sum, csstate->off); 1742594e450bSAl Viro csstate->off += bytes; 1743d879cb83SAl Viro return bytes; 1744d879cb83SAl Viro } 1745d879cb83SAl Viro EXPORT_SYMBOL(csum_and_copy_to_iter); 1746d879cb83SAl Viro 1747d05f4435SSagi Grimberg size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, 1748d05f4435SSagi Grimberg struct iov_iter *i) 1749d05f4435SSagi Grimberg { 17507999096fSHerbert Xu #ifdef CONFIG_CRYPTO_HASH 1751d05f4435SSagi Grimberg struct ahash_request *hash = hashp; 1752d05f4435SSagi Grimberg struct scatterlist sg; 1753d05f4435SSagi Grimberg size_t copied; 1754d05f4435SSagi Grimberg 1755d05f4435SSagi Grimberg copied = copy_to_iter(addr, bytes, i); 1756d05f4435SSagi Grimberg sg_init_one(&sg, addr, copied); 1757d05f4435SSagi Grimberg ahash_request_set_crypt(hash, &sg, NULL, copied); 1758d05f4435SSagi Grimberg crypto_ahash_update(hash); 1759d05f4435SSagi Grimberg return copied; 176027fad74aSYueHaibing #else 176127fad74aSYueHaibing return 0; 176227fad74aSYueHaibing #endif 1763d05f4435SSagi Grimberg } 1764d05f4435SSagi Grimberg EXPORT_SYMBOL(hash_and_copy_to_iter); 1765d05f4435SSagi Grimberg 176666531c65SAl Viro static int iov_npages(const struct iov_iter *i, int maxpages) 1767d879cb83SAl Viro { 176866531c65SAl Viro size_t skip = i->iov_offset, size = i->count; 176966531c65SAl Viro const struct iovec *p; 1770d879cb83SAl Viro int npages = 0; 1771d879cb83SAl Viro 177266531c65SAl Viro for (p = i->iov; size; skip = 0, p++) { 177366531c65SAl Viro unsigned offs = offset_in_page(p->iov_base + skip); 177466531c65SAl Viro size_t len = min(p->iov_len - skip, size); 1775d879cb83SAl Viro 177666531c65SAl Viro if (len) { 177766531c65SAl Viro size -= len; 177866531c65SAl Viro npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); 177966531c65SAl Viro if (unlikely(npages > maxpages)) 178066531c65SAl Viro return maxpages; 178166531c65SAl Viro } 178266531c65SAl Viro } 178366531c65SAl Viro return npages; 178466531c65SAl Viro } 178566531c65SAl Viro 178666531c65SAl Viro static int bvec_npages(const struct iov_iter *i, int maxpages) 178766531c65SAl Viro { 178866531c65SAl Viro size_t skip = i->iov_offset, size = i->count; 178966531c65SAl Viro const struct bio_vec *p; 179066531c65SAl Viro int npages = 0; 179166531c65SAl Viro 179266531c65SAl Viro for (p = i->bvec; size; skip = 0, p++) { 179366531c65SAl Viro unsigned offs = (p->bv_offset + skip) % PAGE_SIZE; 179466531c65SAl Viro size_t len = min(p->bv_len - skip, size); 179566531c65SAl Viro 179666531c65SAl Viro size -= len; 179766531c65SAl Viro npages += DIV_ROUND_UP(offs + len, PAGE_SIZE); 179866531c65SAl Viro if (unlikely(npages > maxpages)) 179966531c65SAl Viro return maxpages; 180066531c65SAl Viro } 180166531c65SAl Viro return npages; 180266531c65SAl Viro } 180366531c65SAl Viro 180466531c65SAl Viro int iov_iter_npages(const struct iov_iter *i, int maxpages) 180566531c65SAl Viro { 180666531c65SAl Viro if (unlikely(!i->count)) 180766531c65SAl Viro return 0; 180866531c65SAl Viro /* iovec and kvec have identical layouts */ 180966531c65SAl Viro if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) 181066531c65SAl Viro return iov_npages(i, maxpages); 181166531c65SAl Viro if (iov_iter_is_bvec(i)) 181266531c65SAl Viro return bvec_npages(i, maxpages); 181366531c65SAl Viro if (iov_iter_is_pipe(i)) { 18148cefc107SDavid Howells unsigned int iter_head; 181566531c65SAl Viro int npages; 1816241699cdSAl Viro size_t off; 1817241699cdSAl Viro 1818241699cdSAl Viro if (!sanity(i)) 1819241699cdSAl Viro return 0; 1820241699cdSAl Viro 18218cefc107SDavid Howells data_start(i, &iter_head, &off); 1822241699cdSAl Viro /* some of this one + all after this one */ 182366531c65SAl Viro npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); 182466531c65SAl Viro return min(npages, maxpages); 182566531c65SAl Viro } 182666531c65SAl Viro if (iov_iter_is_xarray(i)) { 1827e4f8df86SAl Viro unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE; 1828e4f8df86SAl Viro int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE); 182966531c65SAl Viro return min(npages, maxpages); 183066531c65SAl Viro } 183166531c65SAl Viro return 0; 1832d879cb83SAl Viro } 1833d879cb83SAl Viro EXPORT_SYMBOL(iov_iter_npages); 1834d879cb83SAl Viro 1835d879cb83SAl Viro const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) 1836d879cb83SAl Viro { 1837d879cb83SAl Viro *new = *old; 183800e23707SDavid Howells if (unlikely(iov_iter_is_pipe(new))) { 1839241699cdSAl Viro WARN_ON(1); 1840241699cdSAl Viro return NULL; 1841241699cdSAl Viro } 18427ff50620SDavid Howells if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new))) 18439ea9ce04SDavid Howells return NULL; 184400e23707SDavid Howells if (iov_iter_is_bvec(new)) 1845d879cb83SAl Viro return new->bvec = kmemdup(new->bvec, 1846d879cb83SAl Viro new->nr_segs * sizeof(struct bio_vec), 1847d879cb83SAl Viro flags); 1848d879cb83SAl Viro else 1849d879cb83SAl Viro /* iovec and kvec have identical layout */ 1850d879cb83SAl Viro return new->iov = kmemdup(new->iov, 1851d879cb83SAl Viro new->nr_segs * sizeof(struct iovec), 1852d879cb83SAl Viro flags); 1853d879cb83SAl Viro } 1854d879cb83SAl Viro EXPORT_SYMBOL(dup_iter); 1855bc917be8SAl Viro 1856bfdc5970SChristoph Hellwig static int copy_compat_iovec_from_user(struct iovec *iov, 1857bfdc5970SChristoph Hellwig const struct iovec __user *uvec, unsigned long nr_segs) 1858bfdc5970SChristoph Hellwig { 1859bfdc5970SChristoph Hellwig const struct compat_iovec __user *uiov = 1860bfdc5970SChristoph Hellwig (const struct compat_iovec __user *)uvec; 1861bfdc5970SChristoph Hellwig int ret = -EFAULT, i; 1862bfdc5970SChristoph Hellwig 1863a959a978SChristoph Hellwig if (!user_access_begin(uiov, nr_segs * sizeof(*uiov))) 1864bfdc5970SChristoph Hellwig return -EFAULT; 1865bfdc5970SChristoph Hellwig 1866bfdc5970SChristoph Hellwig for (i = 0; i < nr_segs; i++) { 1867bfdc5970SChristoph Hellwig compat_uptr_t buf; 1868bfdc5970SChristoph Hellwig compat_ssize_t len; 1869bfdc5970SChristoph Hellwig 1870bfdc5970SChristoph Hellwig unsafe_get_user(len, &uiov[i].iov_len, uaccess_end); 1871bfdc5970SChristoph Hellwig unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end); 1872bfdc5970SChristoph Hellwig 1873bfdc5970SChristoph Hellwig /* check for compat_size_t not fitting in compat_ssize_t .. */ 1874bfdc5970SChristoph Hellwig if (len < 0) { 1875bfdc5970SChristoph Hellwig ret = -EINVAL; 1876bfdc5970SChristoph Hellwig goto uaccess_end; 1877bfdc5970SChristoph Hellwig } 1878bfdc5970SChristoph Hellwig iov[i].iov_base = compat_ptr(buf); 1879bfdc5970SChristoph Hellwig iov[i].iov_len = len; 1880bfdc5970SChristoph Hellwig } 1881bfdc5970SChristoph Hellwig 1882bfdc5970SChristoph Hellwig ret = 0; 1883bfdc5970SChristoph Hellwig uaccess_end: 1884bfdc5970SChristoph Hellwig user_access_end(); 1885bfdc5970SChristoph Hellwig return ret; 1886bfdc5970SChristoph Hellwig } 1887bfdc5970SChristoph Hellwig 1888bfdc5970SChristoph Hellwig static int copy_iovec_from_user(struct iovec *iov, 1889bfdc5970SChristoph Hellwig const struct iovec __user *uvec, unsigned long nr_segs) 1890fb041b59SDavid Laight { 1891fb041b59SDavid Laight unsigned long seg; 1892bfdc5970SChristoph Hellwig 1893bfdc5970SChristoph Hellwig if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec))) 1894bfdc5970SChristoph Hellwig return -EFAULT; 1895bfdc5970SChristoph Hellwig for (seg = 0; seg < nr_segs; seg++) { 1896bfdc5970SChristoph Hellwig if ((ssize_t)iov[seg].iov_len < 0) 1897bfdc5970SChristoph Hellwig return -EINVAL; 1898bfdc5970SChristoph Hellwig } 1899bfdc5970SChristoph Hellwig 1900bfdc5970SChristoph Hellwig return 0; 1901bfdc5970SChristoph Hellwig } 1902bfdc5970SChristoph Hellwig 1903bfdc5970SChristoph Hellwig struct iovec *iovec_from_user(const struct iovec __user *uvec, 1904bfdc5970SChristoph Hellwig unsigned long nr_segs, unsigned long fast_segs, 1905bfdc5970SChristoph Hellwig struct iovec *fast_iov, bool compat) 1906bfdc5970SChristoph Hellwig { 1907bfdc5970SChristoph Hellwig struct iovec *iov = fast_iov; 1908bfdc5970SChristoph Hellwig int ret; 1909fb041b59SDavid Laight 1910fb041b59SDavid Laight /* 1911bfdc5970SChristoph Hellwig * SuS says "The readv() function *may* fail if the iovcnt argument was 1912bfdc5970SChristoph Hellwig * less than or equal to 0, or greater than {IOV_MAX}. Linux has 1913fb041b59SDavid Laight * traditionally returned zero for zero segments, so... 1914fb041b59SDavid Laight */ 1915bfdc5970SChristoph Hellwig if (nr_segs == 0) 1916bfdc5970SChristoph Hellwig return iov; 1917bfdc5970SChristoph Hellwig if (nr_segs > UIO_MAXIOV) 1918bfdc5970SChristoph Hellwig return ERR_PTR(-EINVAL); 1919fb041b59SDavid Laight if (nr_segs > fast_segs) { 1920fb041b59SDavid Laight iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); 1921bfdc5970SChristoph Hellwig if (!iov) 1922bfdc5970SChristoph Hellwig return ERR_PTR(-ENOMEM); 1923fb041b59SDavid Laight } 1924bfdc5970SChristoph Hellwig 1925bfdc5970SChristoph Hellwig if (compat) 1926bfdc5970SChristoph Hellwig ret = copy_compat_iovec_from_user(iov, uvec, nr_segs); 1927bfdc5970SChristoph Hellwig else 1928bfdc5970SChristoph Hellwig ret = copy_iovec_from_user(iov, uvec, nr_segs); 1929bfdc5970SChristoph Hellwig if (ret) { 1930bfdc5970SChristoph Hellwig if (iov != fast_iov) 1931bfdc5970SChristoph Hellwig kfree(iov); 1932bfdc5970SChristoph Hellwig return ERR_PTR(ret); 1933fb041b59SDavid Laight } 1934bfdc5970SChristoph Hellwig 1935bfdc5970SChristoph Hellwig return iov; 1936bfdc5970SChristoph Hellwig } 1937bfdc5970SChristoph Hellwig 1938bfdc5970SChristoph Hellwig ssize_t __import_iovec(int type, const struct iovec __user *uvec, 1939bfdc5970SChristoph Hellwig unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, 1940bfdc5970SChristoph Hellwig struct iov_iter *i, bool compat) 1941bfdc5970SChristoph Hellwig { 1942bfdc5970SChristoph Hellwig ssize_t total_len = 0; 1943bfdc5970SChristoph Hellwig unsigned long seg; 1944bfdc5970SChristoph Hellwig struct iovec *iov; 1945bfdc5970SChristoph Hellwig 1946bfdc5970SChristoph Hellwig iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); 1947bfdc5970SChristoph Hellwig if (IS_ERR(iov)) { 1948bfdc5970SChristoph Hellwig *iovp = NULL; 1949bfdc5970SChristoph Hellwig return PTR_ERR(iov); 1950fb041b59SDavid Laight } 1951fb041b59SDavid Laight 1952fb041b59SDavid Laight /* 1953bfdc5970SChristoph Hellwig * According to the Single Unix Specification we should return EINVAL if 1954bfdc5970SChristoph Hellwig * an element length is < 0 when cast to ssize_t or if the total length 1955bfdc5970SChristoph Hellwig * would overflow the ssize_t return value of the system call. 1956fb041b59SDavid Laight * 1957fb041b59SDavid Laight * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the 1958fb041b59SDavid Laight * overflow case. 1959fb041b59SDavid Laight */ 1960fb041b59SDavid Laight for (seg = 0; seg < nr_segs; seg++) { 1961fb041b59SDavid Laight ssize_t len = (ssize_t)iov[seg].iov_len; 1962fb041b59SDavid Laight 1963bfdc5970SChristoph Hellwig if (!access_ok(iov[seg].iov_base, len)) { 1964bfdc5970SChristoph Hellwig if (iov != *iovp) 1965bfdc5970SChristoph Hellwig kfree(iov); 1966bfdc5970SChristoph Hellwig *iovp = NULL; 1967bfdc5970SChristoph Hellwig return -EFAULT; 1968fb041b59SDavid Laight } 1969bfdc5970SChristoph Hellwig 1970bfdc5970SChristoph Hellwig if (len > MAX_RW_COUNT - total_len) { 1971bfdc5970SChristoph Hellwig len = MAX_RW_COUNT - total_len; 1972fb041b59SDavid Laight iov[seg].iov_len = len; 1973fb041b59SDavid Laight } 1974bfdc5970SChristoph Hellwig total_len += len; 1975fb041b59SDavid Laight } 1976bfdc5970SChristoph Hellwig 1977bfdc5970SChristoph Hellwig iov_iter_init(i, type, iov, nr_segs, total_len); 1978bfdc5970SChristoph Hellwig if (iov == *iovp) 1979bfdc5970SChristoph Hellwig *iovp = NULL; 1980bfdc5970SChristoph Hellwig else 1981bfdc5970SChristoph Hellwig *iovp = iov; 1982bfdc5970SChristoph Hellwig return total_len; 1983fb041b59SDavid Laight } 1984fb041b59SDavid Laight 1985ffecee4fSVegard Nossum /** 1986ffecee4fSVegard Nossum * import_iovec() - Copy an array of &struct iovec from userspace 1987ffecee4fSVegard Nossum * into the kernel, check that it is valid, and initialize a new 1988ffecee4fSVegard Nossum * &struct iov_iter iterator to access it. 1989ffecee4fSVegard Nossum * 1990ffecee4fSVegard Nossum * @type: One of %READ or %WRITE. 1991bfdc5970SChristoph Hellwig * @uvec: Pointer to the userspace array. 1992ffecee4fSVegard Nossum * @nr_segs: Number of elements in userspace array. 1993ffecee4fSVegard Nossum * @fast_segs: Number of elements in @iov. 1994bfdc5970SChristoph Hellwig * @iovp: (input and output parameter) Pointer to pointer to (usually small 1995ffecee4fSVegard Nossum * on-stack) kernel array. 1996ffecee4fSVegard Nossum * @i: Pointer to iterator that will be initialized on success. 1997ffecee4fSVegard Nossum * 1998ffecee4fSVegard Nossum * If the array pointed to by *@iov is large enough to hold all @nr_segs, 1999ffecee4fSVegard Nossum * then this function places %NULL in *@iov on return. Otherwise, a new 2000ffecee4fSVegard Nossum * array will be allocated and the result placed in *@iov. This means that 2001ffecee4fSVegard Nossum * the caller may call kfree() on *@iov regardless of whether the small 2002ffecee4fSVegard Nossum * on-stack array was used or not (and regardless of whether this function 2003ffecee4fSVegard Nossum * returns an error or not). 2004ffecee4fSVegard Nossum * 200587e5e6daSJens Axboe * Return: Negative error code on error, bytes imported on success 2006ffecee4fSVegard Nossum */ 2007bfdc5970SChristoph Hellwig ssize_t import_iovec(int type, const struct iovec __user *uvec, 2008bc917be8SAl Viro unsigned nr_segs, unsigned fast_segs, 2009bfdc5970SChristoph Hellwig struct iovec **iovp, struct iov_iter *i) 2010bc917be8SAl Viro { 201189cd35c5SChristoph Hellwig return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i, 201289cd35c5SChristoph Hellwig in_compat_syscall()); 2013bc917be8SAl Viro } 2014bc917be8SAl Viro EXPORT_SYMBOL(import_iovec); 2015bc917be8SAl Viro 2016bc917be8SAl Viro int import_single_range(int rw, void __user *buf, size_t len, 2017bc917be8SAl Viro struct iovec *iov, struct iov_iter *i) 2018bc917be8SAl Viro { 2019bc917be8SAl Viro if (len > MAX_RW_COUNT) 2020bc917be8SAl Viro len = MAX_RW_COUNT; 202196d4f267SLinus Torvalds if (unlikely(!access_ok(buf, len))) 2022bc917be8SAl Viro return -EFAULT; 2023bc917be8SAl Viro 2024bc917be8SAl Viro iov->iov_base = buf; 2025bc917be8SAl Viro iov->iov_len = len; 2026bc917be8SAl Viro iov_iter_init(i, rw, iov, 1, len); 2027bc917be8SAl Viro return 0; 2028bc917be8SAl Viro } 2029e1267585SAl Viro EXPORT_SYMBOL(import_single_range); 20308fb0f47aSJens Axboe 20318fb0f47aSJens Axboe /** 20328fb0f47aSJens Axboe * iov_iter_restore() - Restore a &struct iov_iter to the same state as when 20338fb0f47aSJens Axboe * iov_iter_save_state() was called. 20348fb0f47aSJens Axboe * 20358fb0f47aSJens Axboe * @i: &struct iov_iter to restore 20368fb0f47aSJens Axboe * @state: state to restore from 20378fb0f47aSJens Axboe * 20388fb0f47aSJens Axboe * Used after iov_iter_save_state() to bring restore @i, if operations may 20398fb0f47aSJens Axboe * have advanced it. 20408fb0f47aSJens Axboe * 20418fb0f47aSJens Axboe * Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC 20428fb0f47aSJens Axboe */ 20438fb0f47aSJens Axboe void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state) 20448fb0f47aSJens Axboe { 20458fb0f47aSJens Axboe if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) && 20468fb0f47aSJens Axboe !iov_iter_is_kvec(i)) 20478fb0f47aSJens Axboe return; 20488fb0f47aSJens Axboe i->iov_offset = state->iov_offset; 20498fb0f47aSJens Axboe i->count = state->count; 20508fb0f47aSJens Axboe /* 20518fb0f47aSJens Axboe * For the *vec iters, nr_segs + iov is constant - if we increment 20528fb0f47aSJens Axboe * the vec, then we also decrement the nr_segs count. Hence we don't 20538fb0f47aSJens Axboe * need to track both of these, just one is enough and we can deduct 20548fb0f47aSJens Axboe * the other from that. ITER_KVEC and ITER_IOVEC are the same struct 20558fb0f47aSJens Axboe * size, so we can just increment the iov pointer as they are unionzed. 20568fb0f47aSJens Axboe * ITER_BVEC _may_ be the same size on some archs, but on others it is 20578fb0f47aSJens Axboe * not. Be safe and handle it separately. 20588fb0f47aSJens Axboe */ 20598fb0f47aSJens Axboe BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec)); 20608fb0f47aSJens Axboe if (iov_iter_is_bvec(i)) 20618fb0f47aSJens Axboe i->bvec -= state->nr_segs - i->nr_segs; 20628fb0f47aSJens Axboe else 20638fb0f47aSJens Axboe i->iov -= state->nr_segs - i->nr_segs; 20648fb0f47aSJens Axboe i->nr_segs = state->nr_segs; 20658fb0f47aSJens Axboe } 2066