v4.19.13 snapshot.
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
new file mode 100644
index 0000000..8be175d
--- /dev/null
+++ b/lib/iov_iter.c
@@ -0,0 +1,1600 @@
+#include <linux/export.h>
+#include <linux/bvec.h>
+#include <linux/uio.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/splice.h>
+#include <net/checksum.h>
+
+#define PIPE_PARANOIA /* for now */
+
+#define iterate_iovec(i, n, __v, __p, skip, STEP) { \
+ size_t left; \
+ size_t wanted = n; \
+ __p = i->iov; \
+ __v.iov_len = min(n, __p->iov_len - skip); \
+ if (likely(__v.iov_len)) { \
+ __v.iov_base = __p->iov_base + skip; \
+ left = (STEP); \
+ __v.iov_len -= left; \
+ skip += __v.iov_len; \
+ n -= __v.iov_len; \
+ } else { \
+ left = 0; \
+ } \
+ while (unlikely(!left && n)) { \
+ __p++; \
+ __v.iov_len = min(n, __p->iov_len); \
+ if (unlikely(!__v.iov_len)) \
+ continue; \
+ __v.iov_base = __p->iov_base; \
+ left = (STEP); \
+ __v.iov_len -= left; \
+ skip = __v.iov_len; \
+ n -= __v.iov_len; \
+ } \
+ n = wanted - n; \
+}
+
+#define iterate_kvec(i, n, __v, __p, skip, STEP) { \
+ size_t wanted = n; \
+ __p = i->kvec; \
+ __v.iov_len = min(n, __p->iov_len - skip); \
+ if (likely(__v.iov_len)) { \
+ __v.iov_base = __p->iov_base + skip; \
+ (void)(STEP); \
+ skip += __v.iov_len; \
+ n -= __v.iov_len; \
+ } \
+ while (unlikely(n)) { \
+ __p++; \
+ __v.iov_len = min(n, __p->iov_len); \
+ if (unlikely(!__v.iov_len)) \
+ continue; \
+ __v.iov_base = __p->iov_base; \
+ (void)(STEP); \
+ skip = __v.iov_len; \
+ n -= __v.iov_len; \
+ } \
+ n = wanted; \
+}
+
+#define iterate_bvec(i, n, __v, __bi, skip, STEP) { \
+ struct bvec_iter __start; \
+ __start.bi_size = n; \
+ __start.bi_bvec_done = skip; \
+ __start.bi_idx = 0; \
+ for_each_bvec(__v, i->bvec, __bi, __start) { \
+ if (!__v.bv_len) \
+ continue; \
+ (void)(STEP); \
+ } \
+}
+
+#define iterate_all_kinds(i, n, v, I, B, K) { \
+ if (likely(n)) { \
+ size_t skip = i->iov_offset; \
+ if (unlikely(i->type & ITER_BVEC)) { \
+ struct bio_vec v; \
+ struct bvec_iter __bi; \
+ iterate_bvec(i, n, v, __bi, skip, (B)) \
+ } else if (unlikely(i->type & ITER_KVEC)) { \
+ const struct kvec *kvec; \
+ struct kvec v; \
+ iterate_kvec(i, n, v, kvec, skip, (K)) \
+ } else { \
+ const struct iovec *iov; \
+ struct iovec v; \
+ iterate_iovec(i, n, v, iov, skip, (I)) \
+ } \
+ } \
+}
+
+#define iterate_and_advance(i, n, v, I, B, K) { \
+ if (unlikely(i->count < n)) \
+ n = i->count; \
+ if (i->count) { \
+ size_t skip = i->iov_offset; \
+ if (unlikely(i->type & ITER_BVEC)) { \
+ const struct bio_vec *bvec = i->bvec; \
+ struct bio_vec v; \
+ struct bvec_iter __bi; \
+ iterate_bvec(i, n, v, __bi, skip, (B)) \
+ i->bvec = __bvec_iter_bvec(i->bvec, __bi); \
+ i->nr_segs -= i->bvec - bvec; \
+ skip = __bi.bi_bvec_done; \
+ } else if (unlikely(i->type & ITER_KVEC)) { \
+ const struct kvec *kvec; \
+ struct kvec v; \
+ iterate_kvec(i, n, v, kvec, skip, (K)) \
+ if (skip == kvec->iov_len) { \
+ kvec++; \
+ skip = 0; \
+ } \
+ i->nr_segs -= kvec - i->kvec; \
+ i->kvec = kvec; \
+ } else { \
+ const struct iovec *iov; \
+ struct iovec v; \
+ iterate_iovec(i, n, v, iov, skip, (I)) \
+ if (skip == iov->iov_len) { \
+ iov++; \
+ skip = 0; \
+ } \
+ i->nr_segs -= iov - i->iov; \
+ i->iov = iov; \
+ } \
+ i->count -= n; \
+ i->iov_offset = skip; \
+ } \
+}
+
+static int copyout(void __user *to, const void *from, size_t n)
+{
+ if (access_ok(VERIFY_WRITE, to, n)) {
+ kasan_check_read(from, n);
+ n = raw_copy_to_user(to, from, n);
+ }
+ return n;
+}
+
+static int copyin(void *to, const void __user *from, size_t n)
+{
+ if (access_ok(VERIFY_READ, from, n)) {
+ kasan_check_write(to, n);
+ n = raw_copy_from_user(to, from, n);
+ }
+ return n;
+}
+
+static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i)
+{
+ size_t skip, copy, left, wanted;
+ const struct iovec *iov;
+ char __user *buf;
+ void *kaddr, *from;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ might_fault();
+ wanted = bytes;
+ iov = i->iov;
+ skip = i->iov_offset;
+ buf = iov->iov_base + skip;
+ copy = min(bytes, iov->iov_len - skip);
+
+ if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
+ kaddr = kmap_atomic(page);
+ from = kaddr + offset;
+
+ /* first chunk, usually the only one */
+ left = copyout(buf, from, copy);
+ copy -= left;
+ skip += copy;
+ from += copy;
+ bytes -= copy;
+
+ while (unlikely(!left && bytes)) {
+ iov++;
+ buf = iov->iov_base;
+ copy = min(bytes, iov->iov_len);
+ left = copyout(buf, from, copy);
+ copy -= left;
+ skip = copy;
+ from += copy;
+ bytes -= copy;
+ }
+ if (likely(!bytes)) {
+ kunmap_atomic(kaddr);
+ goto done;
+ }
+ offset = from - kaddr;
+ buf += copy;
+ kunmap_atomic(kaddr);
+ copy = min(bytes, iov->iov_len - skip);
+ }
+ /* Too bad - revert to non-atomic kmap */
+
+ kaddr = kmap(page);
+ from = kaddr + offset;
+ left = copyout(buf, from, copy);
+ copy -= left;
+ skip += copy;
+ from += copy;
+ bytes -= copy;
+ while (unlikely(!left && bytes)) {
+ iov++;
+ buf = iov->iov_base;
+ copy = min(bytes, iov->iov_len);
+ left = copyout(buf, from, copy);
+ copy -= left;
+ skip = copy;
+ from += copy;
+ bytes -= copy;
+ }
+ kunmap(page);
+
+done:
+ if (skip == iov->iov_len) {
+ iov++;
+ skip = 0;
+ }
+ i->count -= wanted - bytes;
+ i->nr_segs -= iov - i->iov;
+ i->iov = iov;
+ i->iov_offset = skip;
+ return wanted - bytes;
+}
+
+static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i)
+{
+ size_t skip, copy, left, wanted;
+ const struct iovec *iov;
+ char __user *buf;
+ void *kaddr, *to;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ might_fault();
+ wanted = bytes;
+ iov = i->iov;
+ skip = i->iov_offset;
+ buf = iov->iov_base + skip;
+ copy = min(bytes, iov->iov_len - skip);
+
+ if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
+ kaddr = kmap_atomic(page);
+ to = kaddr + offset;
+
+ /* first chunk, usually the only one */
+ left = copyin(to, buf, copy);
+ copy -= left;
+ skip += copy;
+ to += copy;
+ bytes -= copy;
+
+ while (unlikely(!left && bytes)) {
+ iov++;
+ buf = iov->iov_base;
+ copy = min(bytes, iov->iov_len);
+ left = copyin(to, buf, copy);
+ copy -= left;
+ skip = copy;
+ to += copy;
+ bytes -= copy;
+ }
+ if (likely(!bytes)) {
+ kunmap_atomic(kaddr);
+ goto done;
+ }
+ offset = to - kaddr;
+ buf += copy;
+ kunmap_atomic(kaddr);
+ copy = min(bytes, iov->iov_len - skip);
+ }
+ /* Too bad - revert to non-atomic kmap */
+
+ kaddr = kmap(page);
+ to = kaddr + offset;
+ left = copyin(to, buf, copy);
+ copy -= left;
+ skip += copy;
+ to += copy;
+ bytes -= copy;
+ while (unlikely(!left && bytes)) {
+ iov++;
+ buf = iov->iov_base;
+ copy = min(bytes, iov->iov_len);
+ left = copyin(to, buf, copy);
+ copy -= left;
+ skip = copy;
+ to += copy;
+ bytes -= copy;
+ }
+ kunmap(page);
+
+done:
+ if (skip == iov->iov_len) {
+ iov++;
+ skip = 0;
+ }
+ i->count -= wanted - bytes;
+ i->nr_segs -= iov - i->iov;
+ i->iov = iov;
+ i->iov_offset = skip;
+ return wanted - bytes;
+}
+
+#ifdef PIPE_PARANOIA
+static bool sanity(const struct iov_iter *i)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ int idx = i->idx;
+ int next = pipe->curbuf + pipe->nrbufs;
+ if (i->iov_offset) {
+ struct pipe_buffer *p;
+ if (unlikely(!pipe->nrbufs))
+ goto Bad; // pipe must be non-empty
+ if (unlikely(idx != ((next - 1) & (pipe->buffers - 1))))
+ goto Bad; // must be at the last buffer...
+
+ p = &pipe->bufs[idx];
+ if (unlikely(p->offset + p->len != i->iov_offset))
+ goto Bad; // ... at the end of segment
+ } else {
+ if (idx != (next & (pipe->buffers - 1)))
+ goto Bad; // must be right after the last buffer
+ }
+ return true;
+Bad:
+ printk(KERN_ERR "idx = %d, offset = %zd\n", i->idx, i->iov_offset);
+ printk(KERN_ERR "curbuf = %d, nrbufs = %d, buffers = %d\n",
+ pipe->curbuf, pipe->nrbufs, pipe->buffers);
+ for (idx = 0; idx < pipe->buffers; idx++)
+ printk(KERN_ERR "[%p %p %d %d]\n",
+ pipe->bufs[idx].ops,
+ pipe->bufs[idx].page,
+ pipe->bufs[idx].offset,
+ pipe->bufs[idx].len);
+ WARN_ON(1);
+ return false;
+}
+#else
+#define sanity(i) true
+#endif
+
+static inline int next_idx(int idx, struct pipe_inode_info *pipe)
+{
+ return (idx + 1) & (pipe->buffers - 1);
+}
+
+static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ struct pipe_buffer *buf;
+ size_t off;
+ int idx;
+
+ if (unlikely(bytes > i->count))
+ bytes = i->count;
+
+ if (unlikely(!bytes))
+ return 0;
+
+ if (!sanity(i))
+ return 0;
+
+ off = i->iov_offset;
+ idx = i->idx;
+ buf = &pipe->bufs[idx];
+ if (off) {
+ if (offset == off && buf->page == page) {
+ /* merge with the last one */
+ buf->len += bytes;
+ i->iov_offset += bytes;
+ goto out;
+ }
+ idx = next_idx(idx, pipe);
+ buf = &pipe->bufs[idx];
+ }
+ if (idx == pipe->curbuf && pipe->nrbufs)
+ return 0;
+ pipe->nrbufs++;
+ buf->ops = &page_cache_pipe_buf_ops;
+ get_page(buf->page = page);
+ buf->offset = offset;
+ buf->len = bytes;
+ i->iov_offset = offset + bytes;
+ i->idx = idx;
+out:
+ i->count -= bytes;
+ return bytes;
+}
+
+/*
+ * Fault in one or more iovecs of the given iov_iter, to a maximum length of
+ * bytes. For each iovec, fault in each page that constitutes the iovec.
+ *
+ * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
+ * because it is an invalid address).
+ */
+int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
+{
+ size_t skip = i->iov_offset;
+ const struct iovec *iov;
+ int err;
+ struct iovec v;
+
+ if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
+ iterate_iovec(i, bytes, v, iov, skip, ({
+ err = fault_in_pages_readable(v.iov_base, v.iov_len);
+ if (unlikely(err))
+ return err;
+ 0;}))
+ }
+ return 0;
+}
+EXPORT_SYMBOL(iov_iter_fault_in_readable);
+
+void iov_iter_init(struct iov_iter *i, int direction,
+ const struct iovec *iov, unsigned long nr_segs,
+ size_t count)
+{
+ /* It will get better. Eventually... */
+ if (uaccess_kernel()) {
+ direction |= ITER_KVEC;
+ i->type = direction;
+ i->kvec = (struct kvec *)iov;
+ } else {
+ i->type = direction;
+ i->iov = iov;
+ }
+ i->nr_segs = nr_segs;
+ i->iov_offset = 0;
+ i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_init);
+
+static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
+{
+ char *from = kmap_atomic(page);
+ memcpy(to, from + offset, len);
+ kunmap_atomic(from);
+}
+
+static void memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
+{
+ char *to = kmap_atomic(page);
+ memcpy(to + offset, from, len);
+ kunmap_atomic(to);
+}
+
+static void memzero_page(struct page *page, size_t offset, size_t len)
+{
+ char *addr = kmap_atomic(page);
+ memset(addr + offset, 0, len);
+ kunmap_atomic(addr);
+}
+
+static inline bool allocated(struct pipe_buffer *buf)
+{
+ return buf->ops == &default_pipe_buf_ops;
+}
+
+static inline void data_start(const struct iov_iter *i, int *idxp, size_t *offp)
+{
+ size_t off = i->iov_offset;
+ int idx = i->idx;
+ if (off && (!allocated(&i->pipe->bufs[idx]) || off == PAGE_SIZE)) {
+ idx = next_idx(idx, i->pipe);
+ off = 0;
+ }
+ *idxp = idx;
+ *offp = off;
+}
+
+static size_t push_pipe(struct iov_iter *i, size_t size,
+ int *idxp, size_t *offp)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ size_t off;
+ int idx;
+ ssize_t left;
+
+ if (unlikely(size > i->count))
+ size = i->count;
+ if (unlikely(!size))
+ return 0;
+
+ left = size;
+ data_start(i, &idx, &off);
+ *idxp = idx;
+ *offp = off;
+ if (off) {
+ left -= PAGE_SIZE - off;
+ if (left <= 0) {
+ pipe->bufs[idx].len += size;
+ return size;
+ }
+ pipe->bufs[idx].len = PAGE_SIZE;
+ idx = next_idx(idx, pipe);
+ }
+ while (idx != pipe->curbuf || !pipe->nrbufs) {
+ struct page *page = alloc_page(GFP_USER);
+ if (!page)
+ break;
+ pipe->nrbufs++;
+ pipe->bufs[idx].ops = &default_pipe_buf_ops;
+ pipe->bufs[idx].page = page;
+ pipe->bufs[idx].offset = 0;
+ if (left <= PAGE_SIZE) {
+ pipe->bufs[idx].len = left;
+ return size;
+ }
+ pipe->bufs[idx].len = PAGE_SIZE;
+ left -= PAGE_SIZE;
+ idx = next_idx(idx, pipe);
+ }
+ return size - left;
+}
+
+static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
+ struct iov_iter *i)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ size_t n, off;
+ int idx;
+
+ if (!sanity(i))
+ return 0;
+
+ bytes = n = push_pipe(i, bytes, &idx, &off);
+ if (unlikely(!n))
+ return 0;
+ for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+ size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
+ memcpy_to_page(pipe->bufs[idx].page, off, addr, chunk);
+ i->idx = idx;
+ i->iov_offset = off + chunk;
+ n -= chunk;
+ addr += chunk;
+ }
+ i->count -= bytes;
+ return bytes;
+}
+
+size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
+{
+ const char *from = addr;
+ if (unlikely(i->type & ITER_PIPE))
+ return copy_pipe_to_iter(addr, bytes, i);
+ if (iter_is_iovec(i))
+ might_fault();
+ iterate_and_advance(i, bytes, v,
+ copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
+ memcpy_to_page(v.bv_page, v.bv_offset,
+ (from += v.bv_len) - v.bv_len, v.bv_len),
+ memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
+ )
+
+ return bytes;
+}
+EXPORT_SYMBOL(_copy_to_iter);
+
+#ifdef CONFIG_ARCH_HAS_UACCESS_MCSAFE
+static int copyout_mcsafe(void __user *to, const void *from, size_t n)
+{
+ if (access_ok(VERIFY_WRITE, to, n)) {
+ kasan_check_read(from, n);
+ n = copy_to_user_mcsafe((__force void *) to, from, n);
+ }
+ return n;
+}
+
+static unsigned long memcpy_mcsafe_to_page(struct page *page, size_t offset,
+ const char *from, size_t len)
+{
+ unsigned long ret;
+ char *to;
+
+ to = kmap_atomic(page);
+ ret = memcpy_mcsafe(to + offset, from, len);
+ kunmap_atomic(to);
+
+ return ret;
+}
+
+static size_t copy_pipe_to_iter_mcsafe(const void *addr, size_t bytes,
+ struct iov_iter *i)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ size_t n, off, xfer = 0;
+ int idx;
+
+ if (!sanity(i))
+ return 0;
+
+ bytes = n = push_pipe(i, bytes, &idx, &off);
+ if (unlikely(!n))
+ return 0;
+ for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+ size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
+ unsigned long rem;
+
+ rem = memcpy_mcsafe_to_page(pipe->bufs[idx].page, off, addr,
+ chunk);
+ i->idx = idx;
+ i->iov_offset = off + chunk - rem;
+ xfer += chunk - rem;
+ if (rem)
+ break;
+ n -= chunk;
+ addr += chunk;
+ }
+ i->count -= xfer;
+ return xfer;
+}
+
+/**
+ * _copy_to_iter_mcsafe - copy to user with source-read error exception handling
+ * @addr: source kernel address
+ * @bytes: total transfer length
+ * @iter: destination iterator
+ *
+ * The pmem driver arranges for filesystem-dax to use this facility via
+ * dax_copy_to_iter() for protecting read/write to persistent memory.
+ * Unless / until an architecture can guarantee identical performance
+ * between _copy_to_iter_mcsafe() and _copy_to_iter() it would be a
+ * performance regression to switch more users to the mcsafe version.
+ *
+ * Otherwise, the main differences between this and typical _copy_to_iter().
+ *
+ * * Typical tail/residue handling after a fault retries the copy
+ * byte-by-byte until the fault happens again. Re-triggering machine
+ * checks is potentially fatal so the implementation uses source
+ * alignment and poison alignment assumptions to avoid re-triggering
+ * hardware exceptions.
+ *
+ * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
+ * Compare to copy_to_iter() where only ITER_IOVEC attempts might return
+ * a short copy.
+ *
+ * See MCSAFE_TEST for self-test.
+ */
+size_t _copy_to_iter_mcsafe(const void *addr, size_t bytes, struct iov_iter *i)
+{
+ const char *from = addr;
+ unsigned long rem, curr_addr, s_addr = (unsigned long) addr;
+
+ if (unlikely(i->type & ITER_PIPE))
+ return copy_pipe_to_iter_mcsafe(addr, bytes, i);
+ if (iter_is_iovec(i))
+ might_fault();
+ iterate_and_advance(i, bytes, v,
+ copyout_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
+ ({
+ rem = memcpy_mcsafe_to_page(v.bv_page, v.bv_offset,
+ (from += v.bv_len) - v.bv_len, v.bv_len);
+ if (rem) {
+ curr_addr = (unsigned long) from;
+ bytes = curr_addr - s_addr - rem;
+ return bytes;
+ }
+ }),
+ ({
+ rem = memcpy_mcsafe(v.iov_base, (from += v.iov_len) - v.iov_len,
+ v.iov_len);
+ if (rem) {
+ curr_addr = (unsigned long) from;
+ bytes = curr_addr - s_addr - rem;
+ return bytes;
+ }
+ })
+ )
+
+ return bytes;
+}
+EXPORT_SYMBOL_GPL(_copy_to_iter_mcsafe);
+#endif /* CONFIG_ARCH_HAS_UACCESS_MCSAFE */
+
+size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
+{
+ char *to = addr;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return 0;
+ }
+ if (iter_is_iovec(i))
+ might_fault();
+ iterate_and_advance(i, bytes, v,
+ copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
+ memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+ v.bv_offset, v.bv_len),
+ memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+ )
+
+ return bytes;
+}
+EXPORT_SYMBOL(_copy_from_iter);
+
+bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
+{
+ char *to = addr;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return false;
+ }
+ if (unlikely(i->count < bytes))
+ return false;
+
+ if (iter_is_iovec(i))
+ might_fault();
+ iterate_all_kinds(i, bytes, v, ({
+ if (copyin((to += v.iov_len) - v.iov_len,
+ v.iov_base, v.iov_len))
+ return false;
+ 0;}),
+ memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+ v.bv_offset, v.bv_len),
+ memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+ )
+
+ iov_iter_advance(i, bytes);
+ return true;
+}
+EXPORT_SYMBOL(_copy_from_iter_full);
+
+size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
+{
+ char *to = addr;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return 0;
+ }
+ iterate_and_advance(i, bytes, v,
+ __copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
+ v.iov_base, v.iov_len),
+ memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+ v.bv_offset, v.bv_len),
+ memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+ )
+
+ return bytes;
+}
+EXPORT_SYMBOL(_copy_from_iter_nocache);
+
+#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
+/**
+ * _copy_from_iter_flushcache - write destination through cpu cache
+ * @addr: destination kernel address
+ * @bytes: total transfer length
+ * @iter: source iterator
+ *
+ * The pmem driver arranges for filesystem-dax to use this facility via
+ * dax_copy_from_iter() for ensuring that writes to persistent memory
+ * are flushed through the CPU cache. It is differentiated from
+ * _copy_from_iter_nocache() in that guarantees all data is flushed for
+ * all iterator types. The _copy_from_iter_nocache() only attempts to
+ * bypass the cache for the ITER_IOVEC case, and on some archs may use
+ * instructions that strand dirty-data in the cache.
+ */
+size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
+{
+ char *to = addr;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return 0;
+ }
+ iterate_and_advance(i, bytes, v,
+ __copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
+ v.iov_base, v.iov_len),
+ memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
+ v.bv_offset, v.bv_len),
+ memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
+ v.iov_len)
+ )
+
+ return bytes;
+}
+EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
+#endif
+
+bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
+{
+ char *to = addr;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return false;
+ }
+ if (unlikely(i->count < bytes))
+ return false;
+ iterate_all_kinds(i, bytes, v, ({
+ if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
+ v.iov_base, v.iov_len))
+ return false;
+ 0;}),
+ memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+ v.bv_offset, v.bv_len),
+ memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+ )
+
+ iov_iter_advance(i, bytes);
+ return true;
+}
+EXPORT_SYMBOL(_copy_from_iter_full_nocache);
+
+static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
+{
+ struct page *head = compound_head(page);
+ size_t v = n + offset + page_address(page) - page_address(head);
+
+ if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head))))
+ return true;
+ WARN_ON(1);
+ return false;
+}
+
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i)
+{
+ if (unlikely(!page_copy_sane(page, offset, bytes)))
+ return 0;
+ if (i->type & (ITER_BVEC|ITER_KVEC)) {
+ void *kaddr = kmap_atomic(page);
+ size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
+ kunmap_atomic(kaddr);
+ return wanted;
+ } else if (likely(!(i->type & ITER_PIPE)))
+ return copy_page_to_iter_iovec(page, offset, bytes, i);
+ else
+ return copy_page_to_iter_pipe(page, offset, bytes, i);
+}
+EXPORT_SYMBOL(copy_page_to_iter);
+
+size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i)
+{
+ if (unlikely(!page_copy_sane(page, offset, bytes)))
+ return 0;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return 0;
+ }
+ if (i->type & (ITER_BVEC|ITER_KVEC)) {
+ void *kaddr = kmap_atomic(page);
+ size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
+ kunmap_atomic(kaddr);
+ return wanted;
+ } else
+ return copy_page_from_iter_iovec(page, offset, bytes, i);
+}
+EXPORT_SYMBOL(copy_page_from_iter);
+
+static size_t pipe_zero(size_t bytes, struct iov_iter *i)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ size_t n, off;
+ int idx;
+
+ if (!sanity(i))
+ return 0;
+
+ bytes = n = push_pipe(i, bytes, &idx, &off);
+ if (unlikely(!n))
+ return 0;
+
+ for ( ; n; idx = next_idx(idx, pipe), off = 0) {
+ size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
+ memzero_page(pipe->bufs[idx].page, off, chunk);
+ i->idx = idx;
+ i->iov_offset = off + chunk;
+ n -= chunk;
+ }
+ i->count -= bytes;
+ return bytes;
+}
+
+size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
+{
+ if (unlikely(i->type & ITER_PIPE))
+ return pipe_zero(bytes, i);
+ iterate_and_advance(i, bytes, v,
+ clear_user(v.iov_base, v.iov_len),
+ memzero_page(v.bv_page, v.bv_offset, v.bv_len),
+ memset(v.iov_base, 0, v.iov_len)
+ )
+
+ return bytes;
+}
+EXPORT_SYMBOL(iov_iter_zero);
+
+size_t iov_iter_copy_from_user_atomic(struct page *page,
+ struct iov_iter *i, unsigned long offset, size_t bytes)
+{
+ char *kaddr = kmap_atomic(page), *p = kaddr + offset;
+ if (unlikely(!page_copy_sane(page, offset, bytes))) {
+ kunmap_atomic(kaddr);
+ return 0;
+ }
+ if (unlikely(i->type & ITER_PIPE)) {
+ kunmap_atomic(kaddr);
+ WARN_ON(1);
+ return 0;
+ }
+ iterate_all_kinds(i, bytes, v,
+ copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
+ memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
+ v.bv_offset, v.bv_len),
+ memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+ )
+ kunmap_atomic(kaddr);
+ return bytes;
+}
+EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
+
+static inline void pipe_truncate(struct iov_iter *i)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ if (pipe->nrbufs) {
+ size_t off = i->iov_offset;
+ int idx = i->idx;
+ int nrbufs = (idx - pipe->curbuf) & (pipe->buffers - 1);
+ if (off) {
+ pipe->bufs[idx].len = off - pipe->bufs[idx].offset;
+ idx = next_idx(idx, pipe);
+ nrbufs++;
+ }
+ while (pipe->nrbufs > nrbufs) {
+ pipe_buf_release(pipe, &pipe->bufs[idx]);
+ idx = next_idx(idx, pipe);
+ pipe->nrbufs--;
+ }
+ }
+}
+
+static void pipe_advance(struct iov_iter *i, size_t size)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ if (unlikely(i->count < size))
+ size = i->count;
+ if (size) {
+ struct pipe_buffer *buf;
+ size_t off = i->iov_offset, left = size;
+ int idx = i->idx;
+ if (off) /* make it relative to the beginning of buffer */
+ left += off - pipe->bufs[idx].offset;
+ while (1) {
+ buf = &pipe->bufs[idx];
+ if (left <= buf->len)
+ break;
+ left -= buf->len;
+ idx = next_idx(idx, pipe);
+ }
+ i->idx = idx;
+ i->iov_offset = buf->offset + left;
+ }
+ i->count -= size;
+ /* ... and discard everything past that point */
+ pipe_truncate(i);
+}
+
+void iov_iter_advance(struct iov_iter *i, size_t size)
+{
+ if (unlikely(i->type & ITER_PIPE)) {
+ pipe_advance(i, size);
+ return;
+ }
+ iterate_and_advance(i, size, v, 0, 0, 0)
+}
+EXPORT_SYMBOL(iov_iter_advance);
+
+void iov_iter_revert(struct iov_iter *i, size_t unroll)
+{
+ if (!unroll)
+ return;
+ if (WARN_ON(unroll > MAX_RW_COUNT))
+ return;
+ i->count += unroll;
+ if (unlikely(i->type & ITER_PIPE)) {
+ struct pipe_inode_info *pipe = i->pipe;
+ int idx = i->idx;
+ size_t off = i->iov_offset;
+ while (1) {
+ size_t n = off - pipe->bufs[idx].offset;
+ if (unroll < n) {
+ off -= unroll;
+ break;
+ }
+ unroll -= n;
+ if (!unroll && idx == i->start_idx) {
+ off = 0;
+ break;
+ }
+ if (!idx--)
+ idx = pipe->buffers - 1;
+ off = pipe->bufs[idx].offset + pipe->bufs[idx].len;
+ }
+ i->iov_offset = off;
+ i->idx = idx;
+ pipe_truncate(i);
+ return;
+ }
+ if (unroll <= i->iov_offset) {
+ i->iov_offset -= unroll;
+ return;
+ }
+ unroll -= i->iov_offset;
+ if (i->type & ITER_BVEC) {
+ const struct bio_vec *bvec = i->bvec;
+ while (1) {
+ size_t n = (--bvec)->bv_len;
+ i->nr_segs++;
+ if (unroll <= n) {
+ i->bvec = bvec;
+ i->iov_offset = n - unroll;
+ return;
+ }
+ unroll -= n;
+ }
+ } else { /* same logics for iovec and kvec */
+ const struct iovec *iov = i->iov;
+ while (1) {
+ size_t n = (--iov)->iov_len;
+ i->nr_segs++;
+ if (unroll <= n) {
+ i->iov = iov;
+ i->iov_offset = n - unroll;
+ return;
+ }
+ unroll -= n;
+ }
+ }
+}
+EXPORT_SYMBOL(iov_iter_revert);
+
+/*
+ * Return the count of just the current iov_iter segment.
+ */
+size_t iov_iter_single_seg_count(const struct iov_iter *i)
+{
+ if (unlikely(i->type & ITER_PIPE))
+ return i->count; // it is a silly place, anyway
+ if (i->nr_segs == 1)
+ return i->count;
+ else if (i->type & ITER_BVEC)
+ return min(i->count, i->bvec->bv_len - i->iov_offset);
+ else
+ return min(i->count, i->iov->iov_len - i->iov_offset);
+}
+EXPORT_SYMBOL(iov_iter_single_seg_count);
+
+void iov_iter_kvec(struct iov_iter *i, int direction,
+ const struct kvec *kvec, unsigned long nr_segs,
+ size_t count)
+{
+ BUG_ON(!(direction & ITER_KVEC));
+ i->type = direction;
+ i->kvec = kvec;
+ i->nr_segs = nr_segs;
+ i->iov_offset = 0;
+ i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_kvec);
+
+void iov_iter_bvec(struct iov_iter *i, int direction,
+ const struct bio_vec *bvec, unsigned long nr_segs,
+ size_t count)
+{
+ BUG_ON(!(direction & ITER_BVEC));
+ i->type = direction;
+ i->bvec = bvec;
+ i->nr_segs = nr_segs;
+ i->iov_offset = 0;
+ i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_bvec);
+
+void iov_iter_pipe(struct iov_iter *i, int direction,
+ struct pipe_inode_info *pipe,
+ size_t count)
+{
+ BUG_ON(direction != ITER_PIPE);
+ WARN_ON(pipe->nrbufs == pipe->buffers);
+ i->type = direction;
+ i->pipe = pipe;
+ i->idx = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
+ i->iov_offset = 0;
+ i->count = count;
+ i->start_idx = i->idx;
+}
+EXPORT_SYMBOL(iov_iter_pipe);
+
+unsigned long iov_iter_alignment(const struct iov_iter *i)
+{
+ unsigned long res = 0;
+ size_t size = i->count;
+
+ if (unlikely(i->type & ITER_PIPE)) {
+ if (size && i->iov_offset && allocated(&i->pipe->bufs[i->idx]))
+ return size | i->iov_offset;
+ return size;
+ }
+ iterate_all_kinds(i, size, v,
+ (res |= (unsigned long)v.iov_base | v.iov_len, 0),
+ res |= v.bv_offset | v.bv_len,
+ res |= (unsigned long)v.iov_base | v.iov_len
+ )
+ return res;
+}
+EXPORT_SYMBOL(iov_iter_alignment);
+
+unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
+{
+ unsigned long res = 0;
+ size_t size = i->count;
+
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return ~0U;
+ }
+
+ iterate_all_kinds(i, size, v,
+ (res |= (!res ? 0 : (unsigned long)v.iov_base) |
+ (size != v.iov_len ? size : 0), 0),
+ (res |= (!res ? 0 : (unsigned long)v.bv_offset) |
+ (size != v.bv_len ? size : 0)),
+ (res |= (!res ? 0 : (unsigned long)v.iov_base) |
+ (size != v.iov_len ? size : 0))
+ );
+ return res;
+}
+EXPORT_SYMBOL(iov_iter_gap_alignment);
+
+static inline ssize_t __pipe_get_pages(struct iov_iter *i,
+ size_t maxsize,
+ struct page **pages,
+ int idx,
+ size_t *start)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ ssize_t n = push_pipe(i, maxsize, &idx, start);
+ if (!n)
+ return -EFAULT;
+
+ maxsize = n;
+ n += *start;
+ while (n > 0) {
+ get_page(*pages++ = pipe->bufs[idx].page);
+ idx = next_idx(idx, pipe);
+ n -= PAGE_SIZE;
+ }
+
+ return maxsize;
+}
+
+static ssize_t pipe_get_pages(struct iov_iter *i,
+ struct page **pages, size_t maxsize, unsigned maxpages,
+ size_t *start)
+{
+ unsigned npages;
+ size_t capacity;
+ int idx;
+
+ if (!maxsize)
+ return 0;
+
+ if (!sanity(i))
+ return -EFAULT;
+
+ data_start(i, &idx, start);
+ /* some of this one + all after this one */
+ npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
+ capacity = min(npages,maxpages) * PAGE_SIZE - *start;
+
+ return __pipe_get_pages(i, min(maxsize, capacity), pages, idx, start);
+}
+
+ssize_t iov_iter_get_pages(struct iov_iter *i,
+ struct page **pages, size_t maxsize, unsigned maxpages,
+ size_t *start)
+{
+ if (maxsize > i->count)
+ maxsize = i->count;
+
+ if (unlikely(i->type & ITER_PIPE))
+ return pipe_get_pages(i, pages, maxsize, maxpages, start);
+ iterate_all_kinds(i, maxsize, v, ({
+ unsigned long addr = (unsigned long)v.iov_base;
+ size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+ int n;
+ int res;
+
+ if (len > maxpages * PAGE_SIZE)
+ len = maxpages * PAGE_SIZE;
+ addr &= ~(PAGE_SIZE - 1);
+ n = DIV_ROUND_UP(len, PAGE_SIZE);
+ res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
+ if (unlikely(res < 0))
+ return res;
+ return (res == n ? len : res * PAGE_SIZE) - *start;
+ 0;}),({
+ /* can't be more than PAGE_SIZE */
+ *start = v.bv_offset;
+ get_page(*pages = v.bv_page);
+ return v.bv_len;
+ }),({
+ return -EFAULT;
+ })
+ )
+ return 0;
+}
+EXPORT_SYMBOL(iov_iter_get_pages);
+
+static struct page **get_pages_array(size_t n)
+{
+ return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
+}
+
+static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
+ struct page ***pages, size_t maxsize,
+ size_t *start)
+{
+ struct page **p;
+ ssize_t n;
+ int idx;
+ int npages;
+
+ if (!maxsize)
+ return 0;
+
+ if (!sanity(i))
+ return -EFAULT;
+
+ data_start(i, &idx, start);
+ /* some of this one + all after this one */
+ npages = ((i->pipe->curbuf - idx - 1) & (i->pipe->buffers - 1)) + 1;
+ n = npages * PAGE_SIZE - *start;
+ if (maxsize > n)
+ maxsize = n;
+ else
+ npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
+ p = get_pages_array(npages);
+ if (!p)
+ return -ENOMEM;
+ n = __pipe_get_pages(i, maxsize, p, idx, start);
+ if (n > 0)
+ *pages = p;
+ else
+ kvfree(p);
+ return n;
+}
+
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+ struct page ***pages, size_t maxsize,
+ size_t *start)
+{
+ struct page **p;
+
+ if (maxsize > i->count)
+ maxsize = i->count;
+
+ if (unlikely(i->type & ITER_PIPE))
+ return pipe_get_pages_alloc(i, pages, maxsize, start);
+ iterate_all_kinds(i, maxsize, v, ({
+ unsigned long addr = (unsigned long)v.iov_base;
+ size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+ int n;
+ int res;
+
+ addr &= ~(PAGE_SIZE - 1);
+ n = DIV_ROUND_UP(len, PAGE_SIZE);
+ p = get_pages_array(n);
+ if (!p)
+ return -ENOMEM;
+ res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
+ if (unlikely(res < 0)) {
+ kvfree(p);
+ return res;
+ }
+ *pages = p;
+ return (res == n ? len : res * PAGE_SIZE) - *start;
+ 0;}),({
+ /* can't be more than PAGE_SIZE */
+ *start = v.bv_offset;
+ *pages = p = get_pages_array(1);
+ if (!p)
+ return -ENOMEM;
+ get_page(*p = v.bv_page);
+ return v.bv_len;
+ }),({
+ return -EFAULT;
+ })
+ )
+ return 0;
+}
+EXPORT_SYMBOL(iov_iter_get_pages_alloc);
+
+size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
+ struct iov_iter *i)
+{
+ char *to = addr;
+ __wsum sum, next;
+ size_t off = 0;
+ sum = *csum;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return 0;
+ }
+ iterate_and_advance(i, bytes, v, ({
+ int err = 0;
+ next = csum_and_copy_from_user(v.iov_base,
+ (to += v.iov_len) - v.iov_len,
+ v.iov_len, 0, &err);
+ if (!err) {
+ sum = csum_block_add(sum, next, off);
+ off += v.iov_len;
+ }
+ err ? v.iov_len : 0;
+ }), ({
+ char *p = kmap_atomic(v.bv_page);
+ next = csum_partial_copy_nocheck(p + v.bv_offset,
+ (to += v.bv_len) - v.bv_len,
+ v.bv_len, 0);
+ kunmap_atomic(p);
+ sum = csum_block_add(sum, next, off);
+ off += v.bv_len;
+ }),({
+ next = csum_partial_copy_nocheck(v.iov_base,
+ (to += v.iov_len) - v.iov_len,
+ v.iov_len, 0);
+ sum = csum_block_add(sum, next, off);
+ off += v.iov_len;
+ })
+ )
+ *csum = sum;
+ return bytes;
+}
+EXPORT_SYMBOL(csum_and_copy_from_iter);
+
+bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
+ struct iov_iter *i)
+{
+ char *to = addr;
+ __wsum sum, next;
+ size_t off = 0;
+ sum = *csum;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return false;
+ }
+ if (unlikely(i->count < bytes))
+ return false;
+ iterate_all_kinds(i, bytes, v, ({
+ int err = 0;
+ next = csum_and_copy_from_user(v.iov_base,
+ (to += v.iov_len) - v.iov_len,
+ v.iov_len, 0, &err);
+ if (err)
+ return false;
+ sum = csum_block_add(sum, next, off);
+ off += v.iov_len;
+ 0;
+ }), ({
+ char *p = kmap_atomic(v.bv_page);
+ next = csum_partial_copy_nocheck(p + v.bv_offset,
+ (to += v.bv_len) - v.bv_len,
+ v.bv_len, 0);
+ kunmap_atomic(p);
+ sum = csum_block_add(sum, next, off);
+ off += v.bv_len;
+ }),({
+ next = csum_partial_copy_nocheck(v.iov_base,
+ (to += v.iov_len) - v.iov_len,
+ v.iov_len, 0);
+ sum = csum_block_add(sum, next, off);
+ off += v.iov_len;
+ })
+ )
+ *csum = sum;
+ iov_iter_advance(i, bytes);
+ return true;
+}
+EXPORT_SYMBOL(csum_and_copy_from_iter_full);
+
+size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
+ struct iov_iter *i)
+{
+ const char *from = addr;
+ __wsum sum, next;
+ size_t off = 0;
+ sum = *csum;
+ if (unlikely(i->type & ITER_PIPE)) {
+ WARN_ON(1); /* for now */
+ return 0;
+ }
+ iterate_and_advance(i, bytes, v, ({
+ int err = 0;
+ next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
+ v.iov_base,
+ v.iov_len, 0, &err);
+ if (!err) {
+ sum = csum_block_add(sum, next, off);
+ off += v.iov_len;
+ }
+ err ? v.iov_len : 0;
+ }), ({
+ char *p = kmap_atomic(v.bv_page);
+ next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
+ p + v.bv_offset,
+ v.bv_len, 0);
+ kunmap_atomic(p);
+ sum = csum_block_add(sum, next, off);
+ off += v.bv_len;
+ }),({
+ next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
+ v.iov_base,
+ v.iov_len, 0);
+ sum = csum_block_add(sum, next, off);
+ off += v.iov_len;
+ })
+ )
+ *csum = sum;
+ return bytes;
+}
+EXPORT_SYMBOL(csum_and_copy_to_iter);
+
+int iov_iter_npages(const struct iov_iter *i, int maxpages)
+{
+ size_t size = i->count;
+ int npages = 0;
+
+ if (!size)
+ return 0;
+
+ if (unlikely(i->type & ITER_PIPE)) {
+ struct pipe_inode_info *pipe = i->pipe;
+ size_t off;
+ int idx;
+
+ if (!sanity(i))
+ return 0;
+
+ data_start(i, &idx, &off);
+ /* some of this one + all after this one */
+ npages = ((pipe->curbuf - idx - 1) & (pipe->buffers - 1)) + 1;
+ if (npages >= maxpages)
+ return maxpages;
+ } else iterate_all_kinds(i, size, v, ({
+ unsigned long p = (unsigned long)v.iov_base;
+ npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
+ - p / PAGE_SIZE;
+ if (npages >= maxpages)
+ return maxpages;
+ 0;}),({
+ npages++;
+ if (npages >= maxpages)
+ return maxpages;
+ }),({
+ unsigned long p = (unsigned long)v.iov_base;
+ npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
+ - p / PAGE_SIZE;
+ if (npages >= maxpages)
+ return maxpages;
+ })
+ )
+ return npages;
+}
+EXPORT_SYMBOL(iov_iter_npages);
+
+const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
+{
+ *new = *old;
+ if (unlikely(new->type & ITER_PIPE)) {
+ WARN_ON(1);
+ return NULL;
+ }
+ if (new->type & ITER_BVEC)
+ return new->bvec = kmemdup(new->bvec,
+ new->nr_segs * sizeof(struct bio_vec),
+ flags);
+ else
+ /* iovec and kvec have identical layout */
+ return new->iov = kmemdup(new->iov,
+ new->nr_segs * sizeof(struct iovec),
+ flags);
+}
+EXPORT_SYMBOL(dup_iter);
+
+/**
+ * import_iovec() - Copy an array of &struct iovec from userspace
+ * into the kernel, check that it is valid, and initialize a new
+ * &struct iov_iter iterator to access it.
+ *
+ * @type: One of %READ or %WRITE.
+ * @uvector: Pointer to the userspace array.
+ * @nr_segs: Number of elements in userspace array.
+ * @fast_segs: Number of elements in @iov.
+ * @iov: (input and output parameter) Pointer to pointer to (usually small
+ * on-stack) kernel array.
+ * @i: Pointer to iterator that will be initialized on success.
+ *
+ * If the array pointed to by *@iov is large enough to hold all @nr_segs,
+ * then this function places %NULL in *@iov on return. Otherwise, a new
+ * array will be allocated and the result placed in *@iov. This means that
+ * the caller may call kfree() on *@iov regardless of whether the small
+ * on-stack array was used or not (and regardless of whether this function
+ * returns an error or not).
+ *
+ * Return: 0 on success or negative error code on error.
+ */
+int import_iovec(int type, const struct iovec __user * uvector,
+ unsigned nr_segs, unsigned fast_segs,
+ struct iovec **iov, struct iov_iter *i)
+{
+ ssize_t n;
+ struct iovec *p;
+ n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
+ *iov, &p);
+ if (n < 0) {
+ if (p != *iov)
+ kfree(p);
+ *iov = NULL;
+ return n;
+ }
+ iov_iter_init(i, type, p, nr_segs, n);
+ *iov = p == *iov ? NULL : p;
+ return 0;
+}
+EXPORT_SYMBOL(import_iovec);
+
+#ifdef CONFIG_COMPAT
+#include <linux/compat.h>
+
+int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
+ unsigned nr_segs, unsigned fast_segs,
+ struct iovec **iov, struct iov_iter *i)
+{
+ ssize_t n;
+ struct iovec *p;
+ n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
+ *iov, &p);
+ if (n < 0) {
+ if (p != *iov)
+ kfree(p);
+ *iov = NULL;
+ return n;
+ }
+ iov_iter_init(i, type, p, nr_segs, n);
+ *iov = p == *iov ? NULL : p;
+ return 0;
+}
+#endif
+
+int import_single_range(int rw, void __user *buf, size_t len,
+ struct iovec *iov, struct iov_iter *i)
+{
+ if (len > MAX_RW_COUNT)
+ len = MAX_RW_COUNT;
+ if (unlikely(!access_ok(!rw, buf, len)))
+ return -EFAULT;
+
+ iov->iov_base = buf;
+ iov->iov_len = len;
+ iov_iter_init(i, rw, iov, 1, len);
+ return 0;
+}
+EXPORT_SYMBOL(import_single_range);
+
+int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
+ int (*f)(struct kvec *vec, void *context),
+ void *context)
+{
+ struct kvec w;
+ int err = -EINVAL;
+ if (!bytes)
+ return 0;
+
+ iterate_all_kinds(i, bytes, v, -EINVAL, ({
+ w.iov_base = kmap(v.bv_page) + v.bv_offset;
+ w.iov_len = v.bv_len;
+ err = f(&w, context);
+ kunmap(v.bv_page);
+ err;}), ({
+ w = v;
+ err = f(&w, context);})
+ )
+ return err;
+}
+EXPORT_SYMBOL(iov_iter_for_each_range);