selftests: ublk: support non-O_DIRECT backing files

A subsequent commit will add support for using a backing file to store
integrity data. Since integrity data is accessed in intervals of
metadata_size, which may be much smaller than a logical block on the
backing device, direct I/O cannot be used. Add an argument to
backing_file_tgt_init() to specify the number of files to open for
direct I/O. The remaining files will use buffered I/O. For now, continue
to request direct I/O for all the files.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: calebsander

tools/testing/selftests/ublk/common.c

@@ -12,7 +12,7 @@ void backing_file_tgt_deinit(struct ublk_dev *dev)
 	}
 }
 
-int backing_file_tgt_init(struct ublk_dev *dev)
+int backing_file_tgt_init(struct ublk_dev *dev, unsigned int nr_direct)
 {
 	int fd, i;
 
@@ -25,7 +25,7 @@ int backing_file_tgt_init(struct ublk_dev *dev)
 
 		ublk_dbg(UBLK_DBG_DEV, "%s: file %d: %s\n", __func__, i, file);
 
-		fd = open(file, O_RDWR | O_DIRECT);
+		fd = open(file, O_RDWR | (i < nr_direct ? O_DIRECT : 0));
 		if (fd < 0) {
 			ublk_err("%s: backing file %s can't be opened: %s\n",
 					__func__, file, strerror(errno));

tools/testing/selftests/ublk/file_backed.c

@@ -163,7 +163,7 @@ static int ublk_loop_tgt_init(const struct dev_ctx *ctx, struct ublk_dev *dev)
 		return -EINVAL;
 	}
 
-	ret = backing_file_tgt_init(dev);
+	ret = backing_file_tgt_init(dev, 1);
 	if (ret)
 		return ret;
 

tools/testing/selftests/ublk/kublk.h

@@ -462,6 +462,6 @@ extern const struct ublk_tgt_ops stripe_tgt_ops;
 extern const struct ublk_tgt_ops fault_inject_tgt_ops;
 
 void backing_file_tgt_deinit(struct ublk_dev *dev);
-int backing_file_tgt_init(struct ublk_dev *dev);
+int backing_file_tgt_init(struct ublk_dev *dev, unsigned int nr_direct);
 
 #endif

tools/testing/selftests/ublk/stripe.c

@@ -315,7 +315,7 @@ static int ublk_stripe_tgt_init(const struct dev_ctx *ctx, struct ublk_dev *dev)
 
 	chunk_shift = ilog2(chunk_size);
 
-	ret = backing_file_tgt_init(dev);
+	ret = backing_file_tgt_init(dev, dev->tgt.nr_backing_files);
 	if (ret)
 		return ret;