block: Fix blk_aio_write_zeroes()

Commit 57d6a428 broke blk_aio_write_zeroes() because in some write
functions in the call path don't have an explicit length argument but
reuse qiov->size instead. Which is great, except that write_zeroes
doesn't have a qiov, which this commit interprets as 0 bytes.
Consequently, blk_aio_write_zeroes() didn't effectively do anything.

This patch introduces an explicit acb->bytes in BlkAioEmAIOCB and uses
that instead of acb->rwco.size.

The synchronous version of the function is okay because it does pass a
qiov (with the right size and a NULL pointer as its base).
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

block/block-backend.c

@@ -852,6 +852,7 @@ BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
 typedef struct BlkAioEmAIOCB {
     BlockAIOCB common;
     BlkRwCo rwco;
+    int bytes;
     bool has_returned;
     QEMUBH* bh;
 } BlkAioEmAIOCB;
@@ -877,7 +878,7 @@ static void blk_aio_complete_bh(void *opaque)
     blk_aio_complete(opaque);
 }
 
-static BlockAIOCB *blk_aio_prwv(BlockBackend *blk, int64_t offset,
+static BlockAIOCB *blk_aio_prwv(BlockBackend *blk, int64_t offset, int bytes,
                                 QEMUIOVector *qiov, CoroutineEntry co_entry,
                                 BdrvRequestFlags flags,
                                 BlockCompletionFunc *cb, void *opaque)
@@ -893,6 +894,7 @@ static BlockAIOCB *blk_aio_prwv(BlockBackend *blk, int64_t offset,
         .flags  = flags,
         .ret    = NOT_DONE,
     };
+    acb->bytes = bytes;
     acb->bh = NULL;
     acb->has_returned = false;
 
@@ -913,7 +915,8 @@ static void blk_aio_read_entry(void *opaque)
     BlkAioEmAIOCB *acb = opaque;
     BlkRwCo *rwco = &acb->rwco;
 
-    rwco->ret = blk_co_preadv(rwco->blk, rwco->offset, rwco->qiov->size,
+    assert(rwco->qiov->size == acb->bytes);
+    rwco->ret = blk_co_preadv(rwco->blk, rwco->offset, acb->bytes,
                               rwco->qiov, rwco->flags);
     blk_aio_complete(acb);
 }
@@ -923,8 +926,8 @@ static void blk_aio_write_entry(void *opaque)
     BlkAioEmAIOCB *acb = opaque;
     BlkRwCo *rwco = &acb->rwco;
 
-    rwco->ret = blk_co_pwritev(rwco->blk, rwco->offset,
-                               rwco->qiov ? rwco->qiov->size : 0,
+    assert(!rwco->qiov || rwco->qiov->size == acb->bytes);
+    rwco->ret = blk_co_pwritev(rwco->blk, rwco->offset, acb->bytes,
                                rwco->qiov, rwco->flags);
     blk_aio_complete(acb);
 }
@@ -937,7 +940,8 @@ BlockAIOCB *blk_aio_write_zeroes(BlockBackend *blk, int64_t sector_num,
         return blk_abort_aio_request(blk, cb, opaque, -EINVAL);
     }
 
-    return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS, NULL,
+    return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS,
+                        nb_sectors << BDRV_SECTOR_BITS, NULL,
                         blk_aio_write_entry, BDRV_REQ_ZERO_WRITE, cb, opaque);
 }
 
@@ -994,7 +998,8 @@ BlockAIOCB *blk_aio_readv(BlockBackend *blk, int64_t sector_num,
         return blk_abort_aio_request(blk, cb, opaque, -EINVAL);
     }
 
-    return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS, iov,
+    assert(nb_sectors << BDRV_SECTOR_BITS == iov->size);
+    return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS, iov->size, iov,
                         blk_aio_read_entry, 0, cb, opaque);
 }
 
@@ -1006,7 +1011,8 @@ BlockAIOCB *blk_aio_writev(BlockBackend *blk, int64_t sector_num,
         return blk_abort_aio_request(blk, cb, opaque, -EINVAL);
     }
 
-    return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS, iov,
+    assert(nb_sectors << BDRV_SECTOR_BITS == iov->size);
+    return blk_aio_prwv(blk, sector_num << BDRV_SECTOR_BITS, iov->size, iov,
                         blk_aio_write_entry, 0, cb, opaque);
 }
 

tests/qemu-iotests/033

@@ -57,12 +57,13 @@ do_test()
 	} | $QEMU_IO
 }
 
+for write_zero_cmd in "write -z" "aio_write -z"; do
 for align in 512 4k; do
 	echo
 	echo "== preparing image =="
 	do_test $align "write -P 0xa 0x200 0x400" "$TEST_IMG" | _filter_qemu_io
 	do_test $align "write -P 0xa 0x20000 0x600" "$TEST_IMG" | _filter_qemu_io
-	do_test $align "write -z 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
+	do_test $align "$write_zero_cmd 0x400 0x20000" "$TEST_IMG" | _filter_qemu_io
 
 	echo
 	echo "== verifying patterns (1) =="
@@ -73,7 +74,7 @@ for align in 512 4k; do
 	echo
 	echo "== rewriting zeroes =="
 	do_test $align "write -P 0xb 0x10000 0x10000" "$TEST_IMG" | _filter_qemu_io
-	do_test $align "write -z 0x10000 0x10000" "$TEST_IMG" | _filter_qemu_io
+	do_test $align "$write_zero_cmd 0x10000 0x10000" "$TEST_IMG" | _filter_qemu_io
 
 	echo
 	echo "== verifying patterns (2) =="
@@ -82,7 +83,7 @@ for align in 512 4k; do
 	echo
 	echo "== rewriting unaligned zeroes =="
 	do_test $align "write -P 0xb 0x0 0x1000" "$TEST_IMG" | _filter_qemu_io
-	do_test $align "write -z 0x200 0x200" "$TEST_IMG" | _filter_qemu_io
+	do_test $align "$write_zero_cmd 0x200 0x200" "$TEST_IMG" | _filter_qemu_io
 
 	echo
 	echo "== verifying patterns (3) =="
@@ -92,6 +93,7 @@ for align in 512 4k; do
 
 	echo
 done
+done
 
 # success, all done
 echo "*** done"

tests/qemu-iotests/033.out

@@ -42,6 +42,88 @@ read 3072/3072 bytes at offset 1024
 3 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 
+== preparing image ==
+wrote 1024/1024 bytes at offset 512
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1536/1536 bytes at offset 131072
+1.500 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (1) ==
+read 512/512 bytes at offset 512
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 132096
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== rewriting zeroes ==
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (2) ==
+read 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== rewriting unaligned zeroes ==
+wrote 4096/4096 bytes at offset 0
+4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 512/512 bytes at offset 512
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (3) ==
+read 512/512 bytes at offset 0
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 512
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 3072/3072 bytes at offset 1024
+3 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+
+== preparing image ==
+wrote 1024/1024 bytes at offset 512
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1536/1536 bytes at offset 131072
+1.500 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (1) ==
+read 512/512 bytes at offset 512
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 132096
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== rewriting zeroes ==
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (2) ==
+read 131072/131072 bytes at offset 1024
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== rewriting unaligned zeroes ==
+wrote 4096/4096 bytes at offset 0
+4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 512/512 bytes at offset 512
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verifying patterns (3) ==
+read 512/512 bytes at offset 0
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 512
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 3072/3072 bytes at offset 1024
+3 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+
 == preparing image ==
 wrote 1024/1024 bytes at offset 512
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)