block: Convert BB interface to byte-based discards

Change sector-based blk_discard(), blk_co_discard(), and
blk_aio_discard() to instead be byte-based blk_pdiscard(),
blk_co_pdiscard(), and blk_aio_pdiscard().  NBD gets a lot
simpler now that ignoring the unaligned portion of a
byte-based discard request is handled under the hood by
the block layer.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-6-git-send-email-eblake@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/block-backend.c

@@ -1065,17 +1065,16 @@ BlockAIOCB *blk_aio_flush(BlockBackend *blk,
     return bdrv_aio_flush(blk_bs(blk), cb, opaque);
 }
 
-BlockAIOCB *blk_aio_discard(BlockBackend *blk,
+BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk,
-                            int64_t sector_num, int nb_sectors,
+                             int64_t offset, int count,
                              BlockCompletionFunc *cb, void *opaque)
 {
-    int ret = blk_check_request(blk, sector_num, nb_sectors);
+    int ret = blk_check_byte_request(blk, offset, count);
     if (ret < 0) {
         return blk_abort_aio_request(blk, cb, opaque, ret);
     }
 
-    return bdrv_aio_pdiscard(blk_bs(blk), sector_num << BDRV_SECTOR_BITS,
+    return bdrv_aio_pdiscard(blk_bs(blk), offset, count, cb, opaque);
-                             nb_sectors << BDRV_SECTOR_BITS, cb, opaque);
 }
 
 void blk_aio_cancel(BlockAIOCB *acb)
@@ -1107,15 +1106,14 @@ BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
     return bdrv_aio_ioctl(blk_bs(blk), req, buf, cb, opaque);
 }
 
-int blk_co_discard(BlockBackend *blk, int64_t sector_num, int nb_sectors)
+int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int count)
 {
-    int ret = blk_check_request(blk, sector_num, nb_sectors);
+    int ret = blk_check_byte_request(blk, offset, count);
     if (ret < 0) {
         return ret;
     }
 
-    return bdrv_co_pdiscard(blk_bs(blk), sector_num << BDRV_SECTOR_BITS,
+    return bdrv_co_pdiscard(blk_bs(blk), offset, count);
-                            nb_sectors << BDRV_SECTOR_BITS);
 }
 
 int blk_co_flush(BlockBackend *blk)
@@ -1506,15 +1504,14 @@ int blk_truncate(BlockBackend *blk, int64_t offset)
     return bdrv_truncate(blk_bs(blk), offset);
 }
 
-int blk_discard(BlockBackend *blk, int64_t sector_num, int nb_sectors)
+int blk_pdiscard(BlockBackend *blk, int64_t offset, int count)
 {
-    int ret = blk_check_request(blk, sector_num, nb_sectors);
+    int ret = blk_check_byte_request(blk, offset, count);
     if (ret < 0) {
         return ret;
     }
 
-    return bdrv_pdiscard(blk_bs(blk), sector_num << BDRV_SECTOR_BITS,
+    return bdrv_pdiscard(blk_bs(blk), offset, count);
-                         nb_sectors << BDRV_SECTOR_BITS);
 }
 
 int blk_save_vmstate(BlockBackend *blk, const uint8_t *buf,

block/mirror.c

@@ -303,7 +303,8 @@ static void mirror_do_zero_or_discard(MirrorBlockJob *s,
     s->in_flight++;
     s->sectors_in_flight += nb_sectors;
     if (is_discard) {
-        blk_aio_discard(s->target, sector_num, op->nb_sectors,
+        blk_aio_pdiscard(s->target, sector_num << BDRV_SECTOR_BITS,
+                         op->nb_sectors << BDRV_SECTOR_BITS,
                          mirror_write_complete, op);
     } else {
         blk_aio_pwrite_zeroes(s->target, sector_num * BDRV_SECTOR_SIZE,

hw/block/xen_disk.c

@@ -574,8 +574,9 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
     {
         struct blkif_request_discard *discard_req = (void *)&ioreq->req;
         ioreq->aio_inflight++;
-        blk_aio_discard(blkdev->blk,
+        blk_aio_pdiscard(blkdev->blk,
-                        discard_req->sector_number, discard_req->nr_sectors,
+                         discard_req->sector_number << BDRV_SECTOR_BITS,
+                         discard_req->nr_sectors << BDRV_SECTOR_BITS,
                          qemu_aio_complete, ioreq);
         break;
     }

hw/ide/core.c

@@ -423,7 +423,9 @@ static void ide_issue_trim_cb(void *opaque, int ret)
                 }
 
                 /* Got an entry! Submit and exit.  */
-                iocb->aiocb = blk_aio_discard(iocb->blk, sector, count,
+                iocb->aiocb = blk_aio_pdiscard(iocb->blk,
+                                               sector << BDRV_SECTOR_BITS,
+                                               count << BDRV_SECTOR_BITS,
                                                ide_issue_trim_cb, opaque);
                 return;
             }

hw/scsi/scsi-disk.c

@@ -1609,9 +1609,9 @@ static void scsi_unmap_complete_noio(UnmapCBData *data, int ret)
             goto done;
         }
 
-        r->req.aiocb = blk_aio_discard(s->qdev.conf.blk,
+        r->req.aiocb = blk_aio_pdiscard(s->qdev.conf.blk,
-                                       sector_num * (s->qdev.blocksize / 512),
+                                        sector_num * s->qdev.blocksize,
-                                       nb_sectors * (s->qdev.blocksize / 512),
+                                        nb_sectors * s->qdev.blocksize,
                                         scsi_unmap_complete, data);
         data->count--;
         data->inbuf += 16;

include/sysemu/block-backend.h

@@ -139,15 +139,14 @@ BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
                             BlockCompletionFunc *cb, void *opaque);
 BlockAIOCB *blk_aio_flush(BlockBackend *blk,
                           BlockCompletionFunc *cb, void *opaque);
-BlockAIOCB *blk_aio_discard(BlockBackend *blk,
+BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk, int64_t offset, int count,
-                            int64_t sector_num, int nb_sectors,
                              BlockCompletionFunc *cb, void *opaque);
 void blk_aio_cancel(BlockAIOCB *acb);
 void blk_aio_cancel_async(BlockAIOCB *acb);
 int blk_ioctl(BlockBackend *blk, unsigned long int req, void *buf);
 BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
                           BlockCompletionFunc *cb, void *opaque);
-int blk_co_discard(BlockBackend *blk, int64_t sector_num, int nb_sectors);
+int blk_co_pdiscard(BlockBackend *blk, int64_t offset, int count);
 int blk_co_flush(BlockBackend *blk);
 int blk_flush(BlockBackend *blk);
 int blk_flush_all(void);
@@ -207,7 +206,7 @@ int coroutine_fn blk_co_pwrite_zeroes(BlockBackend *blk, int64_t offset,
 int blk_write_compressed(BlockBackend *blk, int64_t sector_num,
                          const uint8_t *buf, int nb_sectors);
 int blk_truncate(BlockBackend *blk, int64_t offset);
-int blk_discard(BlockBackend *blk, int64_t sector_num, int nb_sectors);
+int blk_pdiscard(BlockBackend *blk, int64_t offset, int count);
 int blk_save_vmstate(BlockBackend *blk, const uint8_t *buf,
                      int64_t pos, int size);
 int blk_load_vmstate(BlockBackend *blk, uint8_t *buf, int64_t pos, int size);

nbd/server.c

@@ -1182,21 +1182,12 @@ static void nbd_trip(void *opaque)
         break;
     case NBD_CMD_TRIM:
         TRACE("Request type is TRIM");
-        /* Ignore unaligned head or tail, until block layer adds byte
+        ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset,
-         * interface */
+                              request.len);
-        if (request.len >= BDRV_SECTOR_SIZE) {
-            request.len -= (request.from + request.len) % BDRV_SECTOR_SIZE;
-            ret = blk_co_discard(exp->blk,
-                                 DIV_ROUND_UP(request.from + exp->dev_offset,
-                                              BDRV_SECTOR_SIZE),
-                                 request.len / BDRV_SECTOR_SIZE);
         if (ret < 0) {
             LOG("discard failed");
             reply.error = -ret;
         }
-        } else {
-            TRACE("trim request too small, ignoring");
-        }
         if (nbd_co_send_reply(req, &reply, 0) < 0) {
             goto out;
         }

qemu-io-cmds.c

@@ -1696,8 +1696,7 @@ static int discard_f(BlockBackend *blk, int argc, char **argv)
     }
 
     gettimeofday(&t1, NULL);
-    ret = blk_discard(blk, offset >> BDRV_SECTOR_BITS,
+    ret = blk_pdiscard(blk, offset, count);
-                      count >> BDRV_SECTOR_BITS);
     gettimeofday(&t2, NULL);
 
     if (ret < 0) {