s390/crash: add missing iterator advance in copy_oldmem_page()

In case old memory was successfully copied the passed iterator
should be advanced as well. Currently copy_oldmem_page() is
always called with single-segment iterator. Should that ever
change - copy_oldmem_user and copy_oldmem_kernel() functions
would need a rework to deal with multi-segment iterators.

Fixes: 5d8de293c224 ("vmcore: convert copy_oldmem_page() to take an iov_iter")
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Tested-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index a2c1c55daec03c8faee196c7edf5ed6b865b3a96..2534a31d25502a90dcf40b7821511567850b72c1 100644 (file)
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -219,6 +219,11 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
        unsigned long src;
        int rc;
 
+       if (!(iter_is_iovec(iter) || iov_iter_is_kvec(iter)))
+               return -EINVAL;
+       /* Multi-segment iterators are not supported */
+       if (iter->nr_segs > 1)
+               return -EINVAL;
        if (!csize)
                return 0;
        src = pfn_to_phys(pfn) + offset;
@@ -228,6 +233,8 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
                rc = copy_oldmem_user(iter->iov->iov_base, src, csize);
        else
                rc = copy_oldmem_kernel(iter->kvec->iov_base, src, csize);
+       if (!rc)
+               iov_iter_advance(iter, csize);
        return rc;
 }