Re: [PATCH v4] scsi: target: tcmu: Fix possible data corruption

[Bodo Stroesser <bostroesser@gmail.com>]

Hi,

just some remarks regarding the new comment.

Bodo

On 17.04.22 07:26, Xiaoguang Wang wrote:

... snip ...

>   static const struct vm_operations_struct tcmu_vm_ops = {
> @@ -3205,12 +3228,19 @@ static void find_free_blocks(void)
>   			udev->dbi_max = block;
>   		}
>   
> +		/*
> +		 * Release the block pages.
> +		 * Also note that since tcmu_vma_fault() gets one extra page
> +		 * refcount, tcmu_blocks_release() won't free pages if pages
> +		 * are in page fault procedure, which means it's safe to

s/in page fault procedure/mapped/

> +		 * call tcmu_blocks_release() before unmap_mapping_range().

"... before unmap_mapping_range(), which drops the refcount of pages it
unmaps and thus releases those pages."

Please feel free to find an even better wording.

> +		 */
> +		pages_freed = tcmu_blocks_release(udev, start, end - 1);
> +
>   		/* Here will truncate the data area from off */
>   		off = udev->data_off + (loff_t)start * udev->data_blk_size;
>   		unmap_mapping_range(udev->inode->i_mapping, off, 0, 1);
>   
> -		/* Release the block pages */
> -		pages_freed = tcmu_blocks_release(udev, start, end - 1);
>   		mutex_unlock(&udev->cmdr_lock);
>   
>   		total_pages_freed += pages_freed;