diff mbox series

[RFC,v1,08/26] io: implement io_pwritev/preadv for QIOChannelFile

Message ID 20230330180336.2791-9-farosas@suse.de
State New
Headers show
Series migration: File based migration with multifd and fixed-ram | expand

Commit Message

Fabiano Rosas March 30, 2023, 6:03 p.m. UTC 
From: Nikolay Borisov <nborisov@suse.com>

The upcoming 'fixed-ram' feature will require qemu to write data to
(and restore from) specific offsets of the migration file.

Add a minimal implementation of pwritev/preadv and expose them via the
io_pwritev and io_preadv interfaces.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
---
 io/channel-file.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
diff mbox series

Patch

diff --git a/io/channel-file.c b/io/channel-file.c
index a0268232da..a3d2f0bcf9 100644
--- a/io/channel-file.c
+++ b/io/channel-file.c
@@ -145,6 +145,56 @@  static ssize_t qio_channel_file_writev(QIOChannel *ioc,
     return ret;
 }
 
+static ssize_t qio_channel_file_preadv(QIOChannel *ioc,
+                                       const struct iovec *iov,
+                                       size_t niov,
+                                       off_t offset,
+                                       Error **errp)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+    ssize_t ret;
+
+ retry:
+    ret = preadv(fioc->fd, iov, niov, offset);
+    if (ret < 0) {
+        if (errno == EAGAIN) {
+            return QIO_CHANNEL_ERR_BLOCK;
+        }
+        if (errno == EINTR) {
+            goto retry;
+        }
+
+        error_setg_errno(errp, errno, "Unable to read from file");
+        return -1;
+    }
+
+    return ret;
+}
+
+static ssize_t qio_channel_file_pwritev(QIOChannel *ioc,
+                                        const struct iovec *iov,
+                                        size_t niov,
+                                        off_t offset,
+                                        Error **errp)
+{
+    QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
+    ssize_t ret;
+
+ retry:
+    ret = pwritev(fioc->fd, iov, niov, offset);
+    if (ret <= 0) {
+        if (errno == EAGAIN) {
+            return QIO_CHANNEL_ERR_BLOCK;
+        }
+        if (errno == EINTR) {
+            goto retry;
+        }
+        error_setg_errno(errp, errno, "Unable to write to file");
+        return -1;
+    }
+    return ret;
+}
+
 static int qio_channel_file_set_blocking(QIOChannel *ioc,
                                          bool enabled,
                                          Error **errp)
@@ -227,6 +277,8 @@  static void qio_channel_file_class_init(ObjectClass *klass,
     ioc_klass->io_writev = qio_channel_file_writev;
     ioc_klass->io_readv = qio_channel_file_readv;
     ioc_klass->io_set_blocking = qio_channel_file_set_blocking;
+    ioc_klass->io_pwritev = qio_channel_file_pwritev;
+    ioc_klass->io_preadv = qio_channel_file_preadv;
     ioc_klass->io_seek = qio_channel_file_seek;
     ioc_klass->io_close = qio_channel_file_close;
     ioc_klass->io_create_watch = qio_channel_file_create_watch;