conf: virtiofs: add rlimit_nofile element

Add an element to configure the rlimit nofile size:

...
<binary>
  <rlimit_nofile size='122333'/>
</binary>
...

Non-positive values are forbidden in 'domaincommon.rng'. Added separate
test file, created by modifying the 'vhost-user-fs-fd-memory.xml'.

Signed-off-by: Adam Julis <ajulis@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

docs/formatdomain.rst

@@ -3734,6 +3734,10 @@ A directory on the host that can be accessed directly from the guest.
    The thread pool helps increase the number of requests in flight when used with
    storage that has a higher latency.  However, it has an overhead, and so for
    fast, low latency filesystems, it may be best to turn it off. ( :since:`Since 8.5.0` )
+   Element ``rlimit_profile`` accepts one attribute ``size`` which defines the
+   maximum number of file descriptors. Non-positive values are forbidden.
+   Although numbers greater than 1M are allowed, the virtiofsd documentation
+   states that in this case its set by virtiofsd to the 1M. ( :since:`Since 10.6.0` )
 ``source``
    The resource on the host that is being accessed in the guest. The ``name``
    attribute must be used with ``type='template'``, and the ``dir`` attribute

src/conf/domain_conf.c

@@ -8868,6 +8868,7 @@ virDomainFSDefParseXML(virDomainXMLOption *xmlopt,
         g_autofree char *queue_size = virXPathString("string(./driver/@queue)", ctxt);
         g_autofree char *binary = virXPathString("string(./binary/@path)", ctxt);
         g_autofree char *thread_pool_size = virXPathString("string(./binary/thread_pool/@size)", ctxt);
+        g_autofree char *rlimit_nofile = virXPathString("string(./binary/rlimit_nofile/@size)", ctxt);
         xmlNodePtr binary_node = virXPathNode("./binary", ctxt);
         xmlNodePtr binary_lock_node = virXPathNode("./binary/lock", ctxt);
         xmlNodePtr binary_cache_node = virXPathNode("./binary/cache", ctxt);
@@ -8891,6 +8892,14 @@ virDomainFSDefParseXML(virDomainXMLOption *xmlopt,
             goto error;
         }
 
+        if (rlimit_nofile &&
+            virStrToLong_ull(rlimit_nofile, NULL, 10, &def->rlimit_nofile) < 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("cannot parse rlimit_nofile '%1$s' for virtiofs"),
+                           rlimit_nofile);
+            goto error;
+        }
+
         if (binary)
             def->binary = virFileSanitizePath(binary);
 
@@ -23415,6 +23424,9 @@ virDomainFSDefFormat(virBuffer *buf,
         if (def->thread_pool_size >= 0)
             virBufferAsprintf(&binaryBuf, "<thread_pool size='%d'/>\n", def->thread_pool_size);
 
+        if (def->rlimit_nofile > 0)
+            virBufferAsprintf(&binaryBuf, "<rlimit_nofile size='%lld'/>\n", def->rlimit_nofile);
+
     }
 
     virDomainVirtioOptionsFormat(&driverAttrBuf, def->virtio);

src/conf/domain_conf.h

@@ -890,6 +890,7 @@ struct _virDomainFSDef {
     bool symlinksResolved;
     char *binary;
     unsigned long long queue_size;
+    unsigned long long rlimit_nofile;
     virTristateSwitch xattr;
     virDomainFSCacheMode cache;
     virTristateSwitch posix_lock;

src/conf/schemas/domaincommon.rng

@@ -3380,6 +3380,15 @@
             </optional>
           </element>
         </optional>
+        <optional>
+          <element name="rlimit_nofile">
+            <optional>
+              <attribute name="size">
+                <data type="positiveInteger"/>
+              </attribute>
+            </optional>
+          </element>
+        </optional>
       </interleave>
     </element>
   </define>

tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.args

@@ -0,0 +1,34 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/var/lib/libvirt/qemu/domain--1-guest \
+USER=test \
+LOGNAME=test \
+XDG_DATA_HOME=/var/lib/libvirt/qemu/domain--1-guest/.local/share \
+XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain--1-guest/.cache \
+XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-guest/.config \
+/usr/bin/qemu-system-x86_64 \
+-name guest=guest,debug-threads=on \
+-S \
+-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain--1-guest/master-key.aes"}' \
+-machine pc,usb=off,dump-guest-core=off,acpi=off \
+-accel kvm \
+-cpu qemu64 \
+-m size=14680064k \
+-overcommit mem-lock=off \
+-smp 2,sockets=2,cores=1,threads=1 \
+-object '{"qom-type":"memory-backend-file","id":"ram-node0","mem-path":"/var/lib/libvirt/qemu/ram/-1-guest/ram-node0","share":true,"size":15032385536}' \
+-numa node,nodeid=0,cpus=0-1,memdev=ram-node0 \
+-uuid 126f2720-6f8e-45ab-a886-ec9277079a67 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server=on,wait=off \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-boot strict=on \
+-chardev socket,id=chr-vu-fs0,path=/var/lib/libvirt/qemu/domain--1-guest/fs0-fs.sock \
+-device '{"driver":"vhost-user-fs-pci","id":"fs0","chardev":"chr-vu-fs0","queue-size":1027,"tag":"mount_tag","bus":"pci.0","addr":"0x2"}' \
+-audiodev '{"id":"audio1","driver":"none"}' \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
+-msg timestamp=on

tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.xml

@@ -0,0 +1 @@
+vhost-user-fs-fd-rlimit.xml

tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.xml

@@ -0,0 +1,50 @@
+<domain type='kvm'>
+  <name>guest</name>
+  <uuid>126f2720-6f8e-45ab-a886-ec9277079a67</uuid>
+  <memory unit='KiB'>14680064</memory>
+  <currentMemory unit='KiB'>14680064</currentMemory>
+  <memoryBacking>
+    <source type='file'/>
+    <access mode='shared'/>
+  </memoryBacking>
+  <vcpu placement='static'>2</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <cpu mode='custom' match='exact' check='none'>
+    <model fallback='forbid'>qemu64</model>
+    <numa>
+      <cell id='0' cpus='0-1' memory='14680064' unit='KiB' memAccess='shared'/>
+    </numa>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='usb' index='0' model='none'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <filesystem type='mount' accessmode='passthrough'>
+      <driver type='virtiofs' queue='1027'/>
+      <binary xattr='on'>
+        <cache mode='always'/>
+        <sandbox mode='chroot'/>
+        <thread_pool size='16'/>
+        <rlimit_nofile size='122333'/>
+      </binary>
+      <idmap>
+        <uid start='0' target='100000' count='65535'/>
+        <gid start='0' target='100000' count='65535'/>
+      </idmap>
+      <source dir='/path'/>
+      <target dir='mount_tag'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+    </filesystem>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <audio id='1' type='none'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxmlconftest.c

@@ -2815,6 +2815,7 @@ mymain(void)
     DO_TEST_CAPS_ARCH_LATEST("launch-security-s390-pv", "s390x");
 
     DO_TEST_CAPS_LATEST("vhost-user-fs-fd-memory");
+    DO_TEST_CAPS_LATEST("vhost-user-fs-fd-rlimit");
     DO_TEST_CAPS_LATEST("vhost-user-fs-hugepages");
     DO_TEST_CAPS_LATEST_PARSE_ERROR("vhost-user-fs-readonly");