[PATCH 3/6] qemu: domain: Add helper for translating disk cachemode to qemu flags

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Add helper which will map values of disk cache mode to the flags which
are accepted by various parts of the qemu block layer.

Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
 src/qemu/qemu_domain.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_domain.h |  6 ++++
 2 files changed, 81 insertions(+)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 9d1c33b54a..20333c9568 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -11920,6 +11920,81 @@ qemuDomainPrepareDiskSource(virDomainDiskDefPtr disk,
 }


+/**
+ * qemuDomainDiskCachemodeFlags:
+ *
+ * Converts disk cachemode to the cache mode options for qemu. Returns -1 for
+ * invalid @cachemode values and fills the flags and returns 0 on success.
+ * Flags may be NULL.
+ */
+int
+qemuDomainDiskCachemodeFlags(int cachemode,
+                             bool *writeback,
+                             bool *direct,
+                             bool *noflush)
+{
+    bool dummy;
+
+    if (!writeback)
+        writeback = &dummy;
+
+    if (!direct)
+        direct = &dummy;
+
+    if (!noflush)
+        noflush = &dummy;
+
+    /* Mapping of cache modes to the attributes according to qemu-options.hx
+     *              │ cache.writeback   cache.direct   cache.no-flush
+     * ─────────────┼─────────────────────────────────────────────────
+     * writeback    │ true              false          false
+     * none         │ true              true           false
+     * writethrough │ false             false          false
+     * directsync   │ false             true           false
+     * unsafe       │ true              false          true
+     */
+    switch ((virDomainDiskCache) cachemode) {
+    case VIR_DOMAIN_DISK_CACHE_DISABLE: /* 'none' */
+        *writeback = true;
+        *direct = true;
+        *noflush = false;
+        break;
+
+    case VIR_DOMAIN_DISK_CACHE_WRITETHRU:
+        *writeback = false;
+        *direct = false;
+        *noflush = false;
+        break;
+
+    case VIR_DOMAIN_DISK_CACHE_WRITEBACK:
+        *writeback = true;
+        *direct = false;
+        *noflush = false;
+        break;
+
+    case VIR_DOMAIN_DISK_CACHE_DIRECTSYNC:
+        *writeback = false;
+        *direct = true;
+        *noflush = false;
+        break;
+
+    case VIR_DOMAIN_DISK_CACHE_UNSAFE:
+        *writeback = true;
+        *direct = false;
+        *noflush = true;
+        break;
+
+    case VIR_DOMAIN_DISK_CACHE_DEFAULT:
+    case VIR_DOMAIN_DISK_CACHE_LAST:
+    default:
+        virReportEnumRangeError(virDomainDiskCache, cachemode);
+        return -1;
+    }
+
+    return 0;
+}
+
+
 void
 qemuProcessEventFree(struct qemuProcessEvent *event)
 {
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 21e12f6594..bbc2e83760 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -1003,4 +1003,10 @@ qemuDomainPrepareDiskSource(virDomainDiskDefPtr disk,
                             qemuDomainObjPrivatePtr priv,
                             virQEMUDriverConfigPtr cfg);

+int
+qemuDomainDiskCachemodeFlags(int cachemode,
+                             bool *writeback,
+                             bool *direct,
+                             bool *noflush);
+
 #endif /* __QEMU_DOMAIN_H__ */
-- 
2.16.2

--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list




[Index of Archives]     [Virt Tools]     [Libvirt Users]     [Lib OS Info]     [Fedora Users]     [Fedora Desktop]     [Fedora SELinux]     [Big List of Linux Books]     [Yosemite News]     [KDE Users]     [Fedora Tools]

  Powered by Linux