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-rw-r--r--mm/iov_iter.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index e2c9a2db4350..45204cd5ccd8 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -235,3 +235,30 @@ void iov_iter_init(struct iov_iter *i, int direction,
i->count = count;
}
EXPORT_SYMBOL(iov_iter_init);
+
+ssize_t iov_iter_get_pages(struct iov_iter *i,
+ struct page **pages, size_t maxsize,
+ size_t *start)
+{
+ size_t offset = i->iov_offset;
+ const struct iovec *iov = i->iov;
+ size_t len;
+ unsigned long addr;
+ int n;
+ int res;
+
+ len = iov->iov_len - offset;
+ if (len > i->count)
+ len = i->count;
+ if (len > maxsize)
+ len = maxsize;
+ addr = (unsigned long)iov->iov_base + offset;
+ len += *start = addr & (PAGE_SIZE - 1);
+ addr &= ~(PAGE_SIZE - 1);
+ n = (len + PAGE_SIZE - 1) / 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;
+}
+EXPORT_SYMBOL(iov_iter_get_pages);