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lxc: be more patient while resolving symlinks

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Resolving symlinks can fail before mounting any file system if one file
system depends on another being mounted. Symlinks are now resolved in
two passes:

  * Before any file system is mounted, but then we are more gentle if
    the source path can't be accessed
  * Right before mounting a file system, so that we are sure that we
    have the resolved path... but then if it can't be accessed we raise
    an error.
This commit is contained in:
Cédric Bosdonnat 2014-11-21 17:45:55 +01:00
parent 433b427ff8
commit 72fecf1813
2 changed files with 54 additions and 24 deletions
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1
src/conf/domain_conf.h
View File

@ -821,6 +821,7 @@ struct _virDomainFSDef {
virDomainDeviceInfo info;
unsigned long long space_hard_limit; /* in bytes */
unsigned long long space_soft_limit; /* in bytes */
bool symlinksResolved;
};

77
src/lxc/lxc_container.c
View File

@ -608,6 +608,48 @@ static int lxcContainerUnmountSubtree(const char *prefix,
return ret;
}
static int lxcContainerResolveSymlinks(virDomainFSDefPtr fs, bool gentle)
{
char *newroot;
if (!fs->src || fs->symlinksResolved)
return 0;
if (access(fs->src, F_OK)) {
if (gentle) {
/* Just ignore the error for the while, we'll try again later */
VIR_DEBUG("Skipped unaccessible '%s'", fs->src);
return 0;
} else {
virReportSystemError(errno,
_("Failed to access '%s'"), fs->src);
return -1;
}
}
VIR_DEBUG("Resolving '%s'", fs->src);
if (virFileResolveAllLinks(fs->src, &newroot) < 0) {
if (gentle) {
VIR_DEBUG("Skipped non-resolvable '%s'", fs->src);
return 0;
} else {
virReportSystemError(errno,
_("Failed to resolve symlink at %s"),
fs->src);
}
return -1;
}
/* Mark it resolved to skip it the next time */
fs->symlinksResolved = true;
VIR_DEBUG("Resolved '%s' to %s", fs->src, newroot);
VIR_FREE(fs->src);
fs->src = newroot;
return 0;
}
static int lxcContainerPrepareRoot(virDomainDefPtr def,
virDomainFSDefPtr root,
@ -634,6 +676,9 @@ static int lxcContainerPrepareRoot(virDomainDefPtr def,
return -1;
}
if (lxcContainerResolveSymlinks(root, false) < 0)
return -1;
if (virAsprintf(&dst, "%s/%s.root",
LXC_STATE_DIR, def->name) < 0)
return -1;
@ -1552,6 +1597,9 @@ static int lxcContainerMountAllFS(virDomainDefPtr vmDef,
if (STREQ(vmDef->fss[i]->dst, "/"))
continue;
if (lxcContainerResolveSymlinks(vmDef->fss[i], false) < 0)
return -1;
if (lxcContainerUnmountSubtree(vmDef->fss[i]->dst,
false) < 0)
return -1;
@ -1735,37 +1783,18 @@ static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
return ret;
}
static int lxcContainerResolveSymlinks(virDomainDefPtr vmDef)
static int lxcContainerResolveAllSymlinks(virDomainDefPtr vmDef)
{
char *newroot;
size_t i;
VIR_DEBUG("Resolving symlinks");
for (i = 0; i < vmDef->nfss; i++) {
virDomainFSDefPtr fs = vmDef->fss[i];
if (!fs->src)
continue;
if (access(fs->src, F_OK)) {
virReportSystemError(errno,
_("Failed to access '%s'"), fs->src);
/* In the first pass, be gentle as some files may
depend on other filesystems to be mounted */
if (lxcContainerResolveSymlinks(fs, true) < 0)
return -1;
}
VIR_DEBUG("Resolving '%s'", fs->src);
if (virFileResolveAllLinks(fs->src, &newroot) < 0) {
virReportSystemError(errno,
_("Failed to resolve symlink at %s"),
fs->src);
return -1;
}
VIR_DEBUG("Resolved '%s' to %s", fs->src, newroot);
VIR_FREE(fs->src);
fs->src = newroot;
}
VIR_DEBUG("Resolved all filesystem symlinks");
@ -2106,7 +2135,7 @@ static int lxcContainerChild(void *data)
goto cleanup;
}
if (lxcContainerResolveSymlinks(vmDef) < 0)
if (lxcContainerResolveAllSymlinks(vmDef) < 0)
goto cleanup;
VIR_DEBUG("Setting up pivot");