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Add support for RAM filesystems for LXC

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Introduce a new syntax for filesystems to allow use of a RAM
filesystem

   <filesystem type='ram'>
      <source usage='10' units='MiB'/>
      <target dir='/mnt'/>
   </filesystem>

The usage units default to KiB to limit consumption of host memory.

* docs/formatdomain.html.in: Document new syntax
* docs/schemas/domaincommon.rng: Add new attributes
* src/conf/domain_conf.c: Parsing/formatting of RAM filesystems
* src/lxc/lxc_container.c: Mounting of RAM filesystems

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange 2012-05-08 17:50:48 +01:00
parent 9c77bf04b0
commit 76b644c362
5 changed files with 137 additions and 22 deletions
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14
docs/formatdomain.html.in
View File

@ -1622,7 +1622,9 @@
</dd>
<dt><code>type='file'</code></dt>
<dd>
Currently unused.
A host file will be treated as an image and mounted in
the guest. The filesystem format will be autodetected.
Only used by LXC driver.
</dd>
<dt><code>type='block'</code></dt>
<dd>
@ -1630,6 +1632,13 @@
format will be autodetected. Only used by LXC driver
<span class="since">(since 0.9.5)</span>.
</dd>
<dt><code>type='ram'</code></dt>
<dd>
An in-memory filesystem, using memory from the host OS.
The source element has a single attribute <code>usage</code>
which gives the memory usage limit in kibibytes. Only used
by LXC driver.
<span class="since"> (since 0.9.13)</span></dd>
</dl>
The filesystem block has an optional attribute <code>accessmode</code>
@ -1669,7 +1678,8 @@
The resource on the host that is being accessed in the guest. The
<code>name</code> attribute must be used with
<code>type='template'</code>, and the <code>dir</code> attribute must
be used with <code>type='mount'</code>
be used with <code>type='mount'</code>. The <code>usage</code> attribute
is used with <code>type='ram'</code> to set the memory limit in KB.
</dd>
<dt><code>target</code></dt>

18
docs/schemas/domaincommon.rng
View File

@ -1290,6 +1290,24 @@
</element>
</interleave>
</group>
<group>
<attribute name="type">
<value>ram</value>
</attribute>
<interleave>
<element name="source">
<attribute name="usage">
<ref name="unsignedLong"/>
</attribute>
<optional>
<attribute name='unit'>
<ref name='unit'/>
</attribute>
</optional>
<empty/>
</element>
</interleave>
</group>
</choice>
<interleave>
<element name="target">

73
src/conf/domain_conf.c
View File

@ -264,7 +264,8 @@ VIR_ENUM_IMPL(virDomainFS, VIR_DOMAIN_FS_TYPE_LAST,
"mount",
"block",
"file",
"template")
"template",
"ram")
VIR_ENUM_IMPL(virDomainFSDriverType, VIR_DOMAIN_FS_DRIVER_TYPE_LAST,
"default",
@ -4213,6 +4214,8 @@ virDomainFSDefParseXML(xmlNodePtr node,
char *target = NULL;
char *accessmode = NULL;
char *wrpolicy = NULL;
char *usage = NULL;
char *unit = NULL;
ctxt->node = node;
@ -4269,6 +4272,10 @@ virDomainFSDefParseXML(xmlNodePtr node,
source = virXMLPropString(cur, "dev");
else if (def->type == VIR_DOMAIN_FS_TYPE_TEMPLATE)
source = virXMLPropString(cur, "name");
else if (def->type == VIR_DOMAIN_FS_TYPE_RAM) {
usage = virXMLPropString(cur, "usage");
unit = virXMLPropString(cur, "unit");
}
} else if (!target &&
xmlStrEqual(cur->name, BAD_CAST "target")) {
target = virXMLPropString(cur, "dir");
@ -4300,7 +4307,8 @@ virDomainFSDefParseXML(xmlNodePtr node,
def->wrpolicy = VIR_DOMAIN_FS_WRPOLICY_DEFAULT;
}
if (source == NULL) {
if (source == NULL &&
def->type != VIR_DOMAIN_FS_TYPE_RAM) {
virDomainReportError(VIR_ERR_NO_SOURCE,
target ? "%s" : NULL, target);
goto error;
@ -4312,6 +4320,25 @@ virDomainFSDefParseXML(xmlNodePtr node,
goto error;
}
if (def->type == VIR_DOMAIN_FS_TYPE_RAM) {
if (!usage) {
virDomainReportError(VIR_ERR_XML_ERROR, "%s",
_("missing 'usage' attribute for RAM filesystem"));
goto error;
}
if (virStrToLong_ull(usage, NULL, 10, &def->usage) < 0) {
virDomainReportError(VIR_ERR_XML_ERROR,
_("cannot parse usage '%s' for RAM filesystem"),
usage);
goto error;
}
if (unit &&
virScaleInteger(&def->usage, unit,
1024, ULONG_LONG_MAX) < 0)
goto error;
fprintf(stderr, "Useage %lld\n", def->usage);
}
def->src = source;
source = NULL;
def->dst = target;
@ -4328,6 +4355,8 @@ cleanup:
VIR_FREE(source);
VIR_FREE(accessmode);
VIR_FREE(wrpolicy);
VIR_FREE(usage);
VIR_FREE(unit);
return def;
@ -11322,27 +11351,31 @@ virDomainFSDefFormat(virBufferPtr buf,
virBufferAddLit(buf, "/>\n");
}
if (def->src) {
switch (def->type) {
case VIR_DOMAIN_FS_TYPE_MOUNT:
virBufferEscapeString(buf, " <source dir='%s'/>\n",
def->src);
break;
switch (def->type) {
case VIR_DOMAIN_FS_TYPE_MOUNT:
virBufferEscapeString(buf, " <source dir='%s'/>\n",
def->src);
break;
case VIR_DOMAIN_FS_TYPE_BLOCK:
virBufferEscapeString(buf, " <source dev='%s'/>\n",
def->src);
break;
case VIR_DOMAIN_FS_TYPE_BLOCK:
virBufferEscapeString(buf, " <source dev='%s'/>\n",
def->src);
break;
case VIR_DOMAIN_FS_TYPE_FILE:
virBufferEscapeString(buf, " <source file='%s'/>\n",
def->src);
break;
case VIR_DOMAIN_FS_TYPE_FILE:
virBufferEscapeString(buf, " <source file='%s'/>\n",
def->src);
break;
case VIR_DOMAIN_FS_TYPE_TEMPLATE:
virBufferEscapeString(buf, " <source name='%s'/>\n",
def->src);
}
case VIR_DOMAIN_FS_TYPE_TEMPLATE:
virBufferEscapeString(buf, " <source name='%s'/>\n",
def->src);
break;
case VIR_DOMAIN_FS_TYPE_RAM:
virBufferAsprintf(buf, " <source usage='%lld' units='KiB'/>\n",
def->usage / 1024);
break;
}
virBufferEscapeString(buf, " <target dir='%s'/>\n",

5
src/conf/domain_conf.h
View File

@ -661,6 +661,7 @@ enum virDomainFSType {
VIR_DOMAIN_FS_TYPE_BLOCK,
VIR_DOMAIN_FS_TYPE_FILE,
VIR_DOMAIN_FS_TYPE_TEMPLATE,
VIR_DOMAIN_FS_TYPE_RAM,
VIR_DOMAIN_FS_TYPE_LAST
};
@ -691,11 +692,15 @@ enum virDomainFSWrpolicy {
VIR_DOMAIN_FS_WRPOLICY_LAST
};
/* Allow 2 MB ram usage */
# define VIR_DOMAIN_FS_RAM_DEFAULT_USAGE (1024 * 2)
struct _virDomainFSDef {
int type;
int fsdriver;
int accessmode;
int wrpolicy; /* enum virDomainFSWrpolicy */
unsigned long long usage;
char *src;
char *dst;
unsigned int readonly : 1;

49
src/lxc/lxc_container.c
View File

@ -335,6 +335,8 @@ static int lxcContainerPivotRoot(virDomainFSDefPtr root)
ret = -1;
VIR_DEBUG("Pivot via %s", root->src);
/* root->parent must be private, so make / private. */
if (mount("", "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0) {
virReportSystemError(errno, "%s",
@ -966,6 +968,47 @@ cleanup:
}
static int lxcContainerMountFSTmpfs(virDomainFSDefPtr fs)
{
int ret = -1;
char *data = NULL;
if (virAsprintf(&data, "size=%lldk", fs->usage) < 0) {
virReportOOMError();
goto cleanup;
}
if (virFileMakePath(fs->dst) < 0) {
virReportSystemError(errno,
_("Failed to create %s"),
fs->dst);
goto cleanup;
}
if (mount("tmpfs", fs->dst, "tmpfs", MS_NOSUID|MS_NODEV, data) < 0) {
virReportSystemError(errno,
_("Failed to mount directory %s as tmpfs"),
fs->dst);
goto cleanup;
}
if (fs->readonly) {
VIR_DEBUG("Binding %s readonly", fs->dst);
if (mount(fs->dst, fs->dst, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
virReportSystemError(errno,
_("Failed to make directory %s readonly"),
fs->dst);
}
}
ret = 0;
cleanup:
VIR_FREE(data);
return ret;
}
static int lxcContainerMountFS(virDomainFSDefPtr fs,
const char *srcprefix)
{
@ -978,6 +1021,10 @@ static int lxcContainerMountFS(virDomainFSDefPtr fs,
if (lxcContainerMountFSBlock(fs, srcprefix) < 0)
return -1;
break;
case VIR_DOMAIN_FS_TYPE_RAM:
if (lxcContainerMountFSTmpfs(fs) < 0)
return -1;
break;
case VIR_DOMAIN_FS_TYPE_FILE:
lxcError(VIR_ERR_INTERNAL_ERROR,
_("Unexpected filesystem type %s"),
@ -1441,6 +1488,8 @@ static int lxcContainerResolveSymlinks(virDomainDefPtr vmDef)
for (i = 0 ; i < vmDef->nfss ; i++) {
virDomainFSDefPtr fs = vmDef->fss[i];
if (!fs->src)
continue;
if (virFileResolveAllLinks(fs->src, &newroot) < 0)
return -1;