block/file: switch to use qemu_open/qemu_create for improved errors

Currently at startup if using cache=none on a filesystem lacking
O_DIRECT such as tmpfs, at startup QEMU prints

qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: file system may not support O_DIRECT
qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Could not open '/tmp/foo.img': Invalid argument

while at QMP level the hint is missing, so QEMU reports just

  "error": {
      "class": "GenericError",
      "desc": "Could not open '/tmp/foo.img': Invalid argument"
  }

which is close to useless for the end user trying to figure out what
they did wrong.

With this change at startup QEMU prints

qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Unable to open '/tmp/foo.img': filesystem does not support O_DIRECT

while at the QMP level QEMU reports a massively more informative

  "error": {
     "class": "GenericError",
     "desc": "Unable to open '/tmp/foo.img': filesystem does not support O_DIRECT"
  }

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

block/file-posix.c

@@ -630,11 +630,10 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
     raw_parse_flags(bdrv_flags, &s->open_flags, false);
 
     s->fd = -1;
-    fd = qemu_open_old(filename, s->open_flags, 0644);
+    fd = qemu_open(filename, s->open_flags, errp);
     ret = fd < 0 ? -errno : 0;
 
     if (ret < 0) {
-        error_setg_file_open(errp, -ret, filename);
         if (ret == -EROFS) {
             ret = -EACCES;
         }
@@ -1032,15 +1031,13 @@ static int raw_reconfigure_getfd(BlockDriverState *bs, int flags,
         }
     }
 
-    /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open_old() */
+    /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
     if (fd == -1) {
         const char *normalized_filename = bs->filename;
         ret = raw_normalize_devicepath(&normalized_filename, errp);
         if (ret >= 0) {
-            assert(!(*open_flags & O_CREAT));
-            fd = qemu_open_old(normalized_filename, *open_flags);
+            fd = qemu_open(normalized_filename, *open_flags, errp);
             if (fd == -1) {
-                error_setg_errno(errp, errno, "Could not reopen file");
                 return -1;
             }
         }
@@ -2411,10 +2408,9 @@ raw_co_create(BlockdevCreateOptions *options, Error **errp)
     }
 
     /* Create file */
-    fd = qemu_open_old(file_opts->filename, O_RDWR | O_CREAT | O_BINARY, 0644);
+    fd = qemu_create(file_opts->filename, O_RDWR | O_BINARY, 0644, errp);
     if (fd < 0) {
         result = -errno;
-        error_setg_errno(errp, -result, "Could not create file");
         goto out;
     }
 
@@ -3335,7 +3331,7 @@ static bool setup_cdrom(char *bsd_path, Error **errp)
     for (index = 0; index < num_of_test_partitions; index++) {
         snprintf(test_partition, sizeof(test_partition), "%ss%d", bsd_path,
                  index);
-        fd = qemu_open_old(test_partition, O_RDONLY | O_BINARY | O_LARGEFILE);
+        fd = qemu_open(test_partition, O_RDONLY | O_BINARY | O_LARGEFILE, NULL);
         if (fd >= 0) {
             partition_found = true;
             qemu_close(fd);
@@ -3653,7 +3649,7 @@ static int cdrom_probe_device(const char *filename)
     int prio = 0;
     struct stat st;
 
-    fd = qemu_open_old(filename, O_RDONLY | O_NONBLOCK);
+    fd = qemu_open(filename, O_RDONLY | O_NONBLOCK, NULL);
     if (fd < 0) {
         goto out;
     }
@@ -3787,7 +3783,7 @@ static int cdrom_reopen(BlockDriverState *bs)
      */
     if (s->fd >= 0)
         qemu_close(s->fd);
-    fd = qemu_open_old(bs->filename, s->open_flags, 0644);
+    fd = qemu_open(bs->filename, s->open_flags, NULL);
     if (fd < 0) {
         s->fd = -1;
         return -EIO;

block/file-win32.c

@@ -596,11 +596,9 @@ static int raw_co_create(BlockdevCreateOptions *options, Error **errp)
         return -EINVAL;
     }
 
-    fd = qemu_open_old(file_opts->filename,
-                       O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
-                       0644);
+    fd = qemu_create(file_opts->filename, O_WRONLY | O_TRUNC | O_BINARY,
+                     0644, errp);
     if (fd < 0) {
-        error_setg_errno(errp, errno, "Could not create file");
         return -EIO;
     }
     set_sparse(fd);