From: Huaisheng Ye <yehs1@xxxxxxxxxx> dcssblk_direct_access() needs to check the validity of pointer pfn for NULL assignment. If pfn equals to NULL, it doesn't need to calculate the value. This is in support of asynchronous memmap init and avoid page lookups when possible. Signed-off-by: Huaisheng Ye <yehs1@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> --- drivers/s390/block/dcssblk.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c index ed607288e696..a645b2c93c34 100644 --- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -923,8 +923,9 @@ __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff, dev_sz = dev_info->end - dev_info->start + 1; *kaddr = (void *) dev_info->start + offset; - *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), - PFN_DEV|PFN_SPECIAL); + if (pfn) + *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), + PFN_DEV|PFN_SPECIAL); return (dev_sz - offset) / PAGE_SIZE; }
