Re: [PATCH v3 4/4] io_uring: add support for zone-append

On Mon, Jul 20, 2020 at 10:44 PM Matthew Wilcox [off-list ref] wrote:

On Mon, Jul 20, 2020 at 10:19:57PM +0530, Kanchan Joshi wrote:

quoted

On Fri, Jul 10, 2020 at 7:41 PM Kanchan Joshi [off-list ref] wrote:

quoted

If we are doing this for zone-append (and not general cases), "__s64
res64" should work -.
64 bits = 1 (sign) + 23 (bytes-copied: cqe->res) + 40
(written-location: chunk_sector bytes limit)

No, don't do this.

 struct io_uring_cqe {
        __u64   user_data;      /* sqe->data submission passed back */
-       __s32   res;            /* result code for this event */
-       __u32   flags;
+       union {
+               struct {
+                       __s32   res;    /* result code for this event */
+                       __u32   flags;
+               };
+               __s64           res64;
+       };
 };

Return the value in bytes in res64, or a negative errno.  Done.

I concur. Can do away with bytes-copied. It's either in its entirety
or not at all.