[PULL 37/43] io/channel: introduce qio_channel_pwrite{v,}_all()

[Fabiano Rosas <farosas@suse.de>]

From: Junjie Cao <junjie.cao@intel.com>

Add positioned write helpers that retry on short writes, matching
the pread_all family from the previous patch.

  qio_channel_pwritev_all()  -- retry loop; returns 0 on success,
                                 -1 on error.
  qio_channel_pwrite_all()   -- single-buffer convenience wrapper.

Signed-off-by: Junjie Cao <junjie.cao@intel.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/qemu-devel/20260413214549.926435-3-junjie.cao@intel.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 include/io/channel.h | 41 +++++++++++++++++++++++++++++++++++++
 io/channel.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)

diff --git a/include/io/channel.h b/include/io/channel.h
index 47af409ede..287d10cd6f 100644
--- a/include/io/channel.h
+++ b/include/io/channel.h
@@ -598,6 +598,47 @@ ssize_t qio_channel_pwritev(QIOChannel *ioc, const struct iovec *iov,
 ssize_t qio_channel_pwrite(QIOChannel *ioc, void *buf, size_t buflen,
                            off_t offset, Error **errp);
 
+/**
+ * qio_channel_pwritev_all:
+ * @ioc: the channel object
+ * @iov: the array of memory regions to write data from
+ * @niov: the length of the @iov array
+ * @offset: the starting offset in the channel to write to
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Writes @iov, possibly blocking or (if the channel is non-blocking)
+ * yielding from the current coroutine multiple times until the entire
+ * content is written.  Otherwise behaves as qio_channel_pwritev().
+ *
+ * Returns: 0 if all bytes were written, or -1 on error
+ */
+int coroutine_mixed_fn qio_channel_pwritev_all(QIOChannel *ioc,
+                                               const struct iovec *iov,
+                                               size_t niov,
+                                               off_t offset,
+                                               Error **errp);
+
+/**
+ * qio_channel_pwrite_all:
+ * @ioc: the channel object
+ * @buf: the memory region to write data from
+ * @buflen: the number of bytes to write from @buf
+ * @offset: the starting offset in the channel to write to
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Writes @buflen bytes from @buf, possibly blocking or (if the
+ * channel is non-blocking) yielding from the current coroutine
+ * multiple times until the entire content is written.  Otherwise
+ * behaves as qio_channel_pwrite().
+ *
+ * Returns: 0 if all bytes were written, or -1 on error
+ */
+int coroutine_mixed_fn qio_channel_pwrite_all(QIOChannel *ioc,
+                                              const void *buf,
+                                              size_t buflen,
+                                              off_t offset,
+                                              Error **errp);
+
 /**
  * qio_channel_preadv
  * @ioc: the channel object
diff --git a/io/channel.c b/io/channel.c
index 52c1abfcbc..2853dadb68 100644
--- a/io/channel.c
+++ b/io/channel.c
@@ -478,6 +478,54 @@ ssize_t qio_channel_pwrite(QIOChannel *ioc, void *buf, size_t buflen,
     return qio_channel_pwritev(ioc, &iov, 1, offset, errp);
 }
 
+int coroutine_mixed_fn qio_channel_pwritev_all(QIOChannel *ioc,
+                                               const struct iovec *iov,
+                                               size_t niov,
+                                               off_t offset,
+                                               Error **errp)
+{
+    int ret = -1;
+    struct iovec *local_iov = g_new(struct iovec, niov);
+    struct iovec *local_iov_head = local_iov;
+    unsigned int nlocal_iov = niov;
+
+    nlocal_iov = iov_copy(local_iov, nlocal_iov,
+                          iov, niov,
+                          0, iov_size(iov, niov));
+
+    while (nlocal_iov > 0) {
+        ssize_t len;
+
+        len = qio_channel_pwritev(ioc, local_iov, nlocal_iov, offset, errp);
+
+        if (len == QIO_CHANNEL_ERR_BLOCK) {
+            qio_channel_wait_cond(ioc, G_IO_OUT);
+            continue;
+        }
+        if (len < 0) {
+            goto cleanup;
+        }
+
+        offset += len;
+        iov_discard_front(&local_iov, &nlocal_iov, len);
+    }
+
+    ret = 0;
+ cleanup:
+    g_free(local_iov_head);
+    return ret;
+}
+
+int coroutine_mixed_fn qio_channel_pwrite_all(QIOChannel *ioc,
+                                              const void *buf,
+                                              size_t buflen,
+                                              off_t offset,
+                                              Error **errp)
+{
+    struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
+    return qio_channel_pwritev_all(ioc, &iov, 1, offset, errp);
+}
+
 ssize_t qio_channel_preadv(QIOChannel *ioc, const struct iovec *iov,
                            size_t niov, off_t offset, Error **errp)
 {
-- 
2.51.0