[PATCH] conf: virtiofs: add rlimit_nofile element

Adam Julis posted 1 patch 5 months ago
Failed in applying to current master (apply log)
docs/formatdomain.rst                         |  4 ++
src/conf/domain_conf.c                        | 12 +++++
src/conf/domain_conf.h                        |  1 +
src/conf/schemas/domaincommon.rng             |  9 ++++
...vhost-user-fs-fd-rlimit.x86_64-latest.args | 34 +++++++++++++
.../vhost-user-fs-fd-rlimit.x86_64-latest.xml | 50 +++++++++++++++++++
.../vhost-user-fs-fd-rlimit.xml               | 50 +++++++++++++++++++
tests/qemuxmlconftest.c                       |  1 +
8 files changed, 161 insertions(+)
create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.args
create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.xml
create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.xml
[PATCH] conf: virtiofs: add rlimit_nofile element
Posted by Adam Julis 5 months ago
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'.

Resolves: https://gitlab.com/libvirt/libvirt/-/issues/485
Signed-off-by: Adam Julis <ajulis@redhat.com>
---
 docs/formatdomain.rst                         |  4 ++
 src/conf/domain_conf.c                        | 12 +++++
 src/conf/domain_conf.h                        |  1 +
 src/conf/schemas/domaincommon.rng             |  9 ++++
 ...vhost-user-fs-fd-rlimit.x86_64-latest.args | 34 +++++++++++++
 .../vhost-user-fs-fd-rlimit.x86_64-latest.xml | 50 +++++++++++++++++++
 .../vhost-user-fs-fd-rlimit.xml               | 50 +++++++++++++++++++
 tests/qemuxmlconftest.c                       |  1 +
 8 files changed, 161 insertions(+)
 create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.args
 create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.xml
 create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.xml

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index ca33a2a570..10584dfe83 100644
--- a/docs/formatdomain.rst
+++ b/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
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 32df908d95..6733857a3a 100644
--- a/src/conf/domain_conf.c
+++ b/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);
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 0fcc4f1f9b..8283493dfc 100644
--- a/src/conf/domain_conf.h
+++ b/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;
diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng
index 2d23fcf123..ab5374d5f0 100644
--- a/src/conf/schemas/domaincommon.rng
+++ b/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>
diff --git a/tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.args b/tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.args
new file mode 100644
index 0000000000..b4c2e3fe98
--- /dev/null
+++ b/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
diff --git a/tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.xml b/tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.xml
new file mode 100644
index 0000000000..2983d3f275
--- /dev/null
+++ b/tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.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>
diff --git a/tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.xml b/tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.xml
new file mode 100644
index 0000000000..2983d3f275
--- /dev/null
+++ b/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>
diff --git a/tests/qemuxmlconftest.c b/tests/qemuxmlconftest.c
index 389d31800b..2aaf6103db 100644
--- a/tests/qemuxmlconftest.c
+++ b/tests/qemuxmlconftest.c
@@ -2814,6 +2814,7 @@ 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");
 
-- 
2.45.2
Re: [PATCH] conf: virtiofs: add rlimit_nofile element
Posted by Daniel P. Berrangé 4 months, 3 weeks ago
On Tue, Jul 16, 2024 at 11:40:36AM +0200, Adam Julis wrote:
> Add an element to configure the rlimit nofile size:
> 
> ...
> <binary>
>   <rlimit_nofile size='122333'/>
> </binary>

I think this XML design is sub-optimal in a number of ways

 * "rlimit" is an implementation detail which is
   something we hide from XML generally

 * "nofile" is a terrible historic UNIX naming choice which
   we shouldn't reuse IMHO. 

 * The extra "size" attribute is redundant given the "no"
   in "nofile"

How about we change this before release to something like

   <max_files>123458</max_files>

Or

   <openfiles max="123456"/>

Or

   <openfiles limit="123456"/>



> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
> index ca33a2a570..10584dfe83 100644
> --- a/docs/formatdomain.rst
> +++ b/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

"rlimit_profile" is not the element name

> +   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` )

We shouldn't list current point-in-time limitations of current backend
driver impl in the XML schema.

IOW, rather than saying 1M is a limit, we should be saying

   "The upper bound on the number of open files is implementation defined"

>  ``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

With regards,
Daniel
-- 
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Re: [PATCH] conf: virtiofs: add rlimit_nofile element
Posted by Michal Prívozník 4 months, 4 weeks ago
On 7/16/24 11:40, Adam Julis wrote:
> 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'.
> 
> Resolves: https://gitlab.com/libvirt/libvirt/-/issues/485

This patch alone does not resolves the issue. We tend to put it into the
very last commit that fixes the issue.

> Signed-off-by: Adam Julis <ajulis@redhat.com>
> ---
>  docs/formatdomain.rst                         |  4 ++
>  src/conf/domain_conf.c                        | 12 +++++
>  src/conf/domain_conf.h                        |  1 +
>  src/conf/schemas/domaincommon.rng             |  9 ++++
>  ...vhost-user-fs-fd-rlimit.x86_64-latest.args | 34 +++++++++++++
>  .../vhost-user-fs-fd-rlimit.x86_64-latest.xml | 50 +++++++++++++++++++
>  .../vhost-user-fs-fd-rlimit.xml               | 50 +++++++++++++++++++
>  tests/qemuxmlconftest.c                       |  1 +
>  8 files changed, 161 insertions(+)
>  create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.args
>  create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.x86_64-latest.xml
>  create mode 100644 tests/qemuxmlconfdata/vhost-user-fs-fd-rlimit.xml

Since .xml and -latest.xml files are identical I suggest turning
-latest.xml into a symlink pointing to the input .xml.


Oh, and please next time, when you're sending two or more patches do not
forget the cover letter.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

Michal