[libvirt RFCv11 16/33] qemu: saveimage: update virQEMUSaveFd struct for parallel save

[Claudio Fontana <cfontana@xxxxxxx>]

add nchannels to the struct and adapt the APIs slightly.
Add a new API virQEMUSaveFdAddChannels to set the number of channels,
which might not be known at Init time.

Signed-off-by: Claudio Fontana <cfontana@xxxxxxx>
---
 src/qemu/qemu_driver.c    | 10 +++++-----
 src/qemu/qemu_saveimage.c | 27 ++++++++++++++++++++++++---
 src/qemu/qemu_saveimage.h |  6 +++++-
 3 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 986bbf9e58..d403ff6bf2 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5883,7 +5883,7 @@ qemuDomainRestoreInternal(virConnectPtr conn,
         }
         oflags |= O_DIRECT;
     }
-    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg) < 0)
+    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg, false) < 0)
         return -1;
     if (qemuSaveImageOpen(driver, NULL, &def, &data, false, &saveFd) < 0)
         goto cleanup;
@@ -6017,7 +6017,7 @@ qemuDomainSaveImageGetXMLDesc(virConnectPtr conn, const char *path,
 
     virCheckFlags(VIR_DOMAIN_SAVE_IMAGE_XML_SECURE, NULL);
 
-    if (virQEMUSaveFdInit(&saveFd, path, O_RDONLY, cfg) < 0)
+    if (virQEMUSaveFdInit(&saveFd, path, O_RDONLY, cfg, false) < 0)
         return NULL;
     if (qemuSaveImageOpen(driver, NULL, &def, &data, false, &saveFd) < 0)
         goto cleanup;
@@ -6055,7 +6055,7 @@ qemuDomainSaveImageDefineXML(virConnectPtr conn, const char *path,
     else if (flags & VIR_DOMAIN_SAVE_PAUSED)
         state = 0;
 
-    if (virQEMUSaveFdInit(&saveFd, path, O_RDWR, cfg) < 0)
+    if (virQEMUSaveFdInit(&saveFd, path, O_RDWR, cfg, false) < 0)
         return -1;
     if (qemuSaveImageOpen(driver, NULL, &def, &data, false, &saveFd) < 0)
         goto cleanup;
@@ -6136,7 +6136,7 @@ qemuDomainManagedSaveGetXMLDesc(virDomainPtr dom, unsigned int flags)
         goto cleanup;
     }
 
-    if (virQEMUSaveFdInit(&saveFd, path, O_RDONLY, cfg) < 0)
+    if (virQEMUSaveFdInit(&saveFd, path, O_RDONLY, cfg, false) < 0)
         goto cleanup;
     if (qemuSaveImageOpen(driver, priv->qemuCaps, &def, &data, false,
                           &saveFd) < 0)
@@ -6212,7 +6212,7 @@ qemuDomainObjRestore(virConnectPtr conn,
         }
         oflags |= O_DIRECT;
     }
-    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg) < 0)
+    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg, false) < 0)
         goto cleanup;
     ret = qemuSaveImageOpen(driver, NULL, &def, &data, true, &saveFd);
     if (ret < 0) {
diff --git a/src/qemu/qemu_saveimage.c b/src/qemu/qemu_saveimage.c
index 70ded3c439..6418114d8a 100644
--- a/src/qemu/qemu_saveimage.c
+++ b/src/qemu/qemu_saveimage.c
@@ -403,12 +403,13 @@ qemuSaveImageGetCompressionCommand(virQEMUSaveFormat compression)
  * @base:     the file name
  * @oflags    the file descriptor open flags
  * @cfg:      the driver config
+ * @parallel: whether parallel save/restore is enabled
  *
  * Returns -1 on error, 0 on success,
  * and in both cases virQEMUSaveFdFini must be called to free resources.
  */
 int virQEMUSaveFdInit(virQEMUSaveFd *saveFd, const char *base,
-                      int oflags, virQEMUDriverConfig *cfg)
+                      int oflags, virQEMUDriverConfig *cfg, bool parallel)
 {
     unsigned int wrapperFlags = VIR_FILE_WRAPPER_NON_BLOCKING;
     bool isCreat = oflags & O_CREAT;
@@ -430,11 +431,14 @@ int virQEMUSaveFdInit(virQEMUSaveFd *saveFd, const char *base,
     }
     if (saveFd->fd < 0)
         return -1;
+
+    saveFd->nchannels = 0;
     /*
+     * iohelper Wrapper is never required for multifd parallel save.
      * For O_CREAT, we always add the wrapper,
      * and for !O_CREAT, we only add the wrapper if using O_DIRECT.
      */
-    if (isDirect || isCreat) {
+    if (!parallel && (isDirect || isCreat)) {
         saveFd->wrapper = virFileWrapperFdNew(&saveFd->fd, saveFd->path, wrapperFlags);
         if (!saveFd->wrapper)
             return -1;
@@ -442,6 +446,23 @@ int virQEMUSaveFdInit(virQEMUSaveFd *saveFd, const char *base,
     return 0;
 }
 
+/*
+ * virQEMUSaveFdAddChannels: add multifd channels to a virQEMUSaveFd
+ *
+ * @saveFd:   the structure to add channels to.
+ * @nchannels:number of multifd channels, must be > 0.
+ *
+ * Returns -1 on error, 0 on success.
+ */
+int virQEMUSaveFdAddChannels(virQEMUSaveFd *saveFd, int nchannels)
+{
+    if (nchannels > 0) {
+        saveFd->nchannels = nchannels;
+        return 0;
+    }
+    return -1;
+}
+
 /*
  * virQEMUSaveFdClose: close a virQEMUSaveFd descriptor with normal close.
  *
@@ -539,7 +560,7 @@ qemuSaveImageCreate(virQEMUDriver *driver,
         oflags |= O_DIRECT;
     }
 
-    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg) < 0)
+    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg, false) < 0)
         goto cleanup;
     if (qemuSecuritySetImageFDLabel(driver->securityManager, vm->def, saveFd.fd) < 0)
         goto cleanup;
diff --git a/src/qemu/qemu_saveimage.h b/src/qemu/qemu_saveimage.h
index 9b04af2fb9..dcc9aa7d63 100644
--- a/src/qemu/qemu_saveimage.h
+++ b/src/qemu/qemu_saveimage.h
@@ -62,17 +62,21 @@ struct _virQEMUSaveFd {
     bool need_unlink;
     virFileWrapperFd *wrapper;
     virQEMUDriverConfig *cfg;
+    int nchannels;
 };
 
 #define QEMU_SAVEFD_INVALID (virQEMUSaveFd) { \
         .path = NULL, .fd = -1, .oflags = 0, \
         .need_unlink = false, .wrapper = NULL, .cfg = NULL, \
+        .nchannels = 0, \
 }
 
 int virQEMUSaveFdInit(virQEMUSaveFd *saveFd, const char *base,
-                      int oflags, virQEMUDriverConfig *cfg)
+                      int oflags, virQEMUDriverConfig *cfg, bool parallel)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(4);
 
+int virQEMUSaveFdAddChannels(virQEMUSaveFd *saveFd, int nchannels);
+
 int virQEMUSaveFdClose(virQEMUSaveFd *saveFd, virDomainObj *vm);
 
 int virQEMUSaveFdFini(virQEMUSaveFd *saveFd, virDomainObj *vm, int ret);
-- 
2.26.2