diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/iov_iter.c | 33 |
1 files changed, 21 insertions, 12 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c index c88908f0f138..ce3d4f610626 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -430,33 +430,42 @@ out: } /* + * fault_in_iov_iter_readable - fault in iov iterator for reading + * @i: iterator + * @size: maximum length + * * 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. + * @size. For each iovec, fault in each page that constitutes the iovec. + * + * Returns the number of bytes not faulted in (like copy_to_user() and + * copy_from_user()). * - * Return 0 on success, or non-zero if the memory could not be accessed (i.e. - * because it is an invalid address). + * Always returns 0 for non-userspace iterators. */ -int iov_iter_fault_in_readable(const struct iov_iter *i, size_t bytes) +size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size) { if (iter_is_iovec(i)) { + size_t count = min(size, iov_iter_count(i)); const struct iovec *p; size_t skip; - if (bytes > i->count) - bytes = i->count; - for (p = i->iov, skip = i->iov_offset; bytes; p++, skip = 0) { - size_t len = min(bytes, p->iov_len - skip); + size -= count; + for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) { + size_t len = min(count, p->iov_len - skip); + size_t ret; if (unlikely(!len)) continue; - if (fault_in_readable(p->iov_base + skip, len)) - return -EFAULT; - bytes -= len; + ret = fault_in_readable(p->iov_base + skip, len); + count -= len - ret; + if (ret) + break; } + return count + size; } return 0; } -EXPORT_SYMBOL(iov_iter_fault_in_readable); +EXPORT_SYMBOL(fault_in_iov_iter_readable); void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov, unsigned long nr_segs, |