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mount_entry: use statvfs

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Use statvfs instead of parsing /proc/self/mountinfo to check for the
flags we need to and into the msbind mount flags.  This will be faster
and the code is cleaner.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
This commit is contained in:
Serge Hallyn 2014-08-20 22:51:43 +00:00 committed by Stéphane Graber
parent d79067a726
commit 2938f7c82b
1 changed files with 30 additions and 52 deletions
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82
src/lxc/conf.c
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@ -36,6 +36,7 @@
#include <pwd.h>
#include <grp.h>
#include <time.h>
#include <sys/statvfs.h>
#if HAVE_PTY_H
#include <pty.h>
@ -1952,49 +1953,12 @@ static char *get_field(char *src, int nfields)
return p;
}
static unsigned long get_mount_flags(const char *path)
{
FILE *f = fopen("/proc/self/mountinfo", "r");
char *line = NULL;
size_t len = 0;
unsigned long flags = 0;
if (!f) {
WARN("Failed to open /proc/self/mountinfo");
return 0;
}
while (getline(&line, &len, f) != -1) {
char *target, *opts, *p, *saveptr = NULL;
target = get_field(line, 4);
if (!target)
continue;
opts = get_field(target, 2);
if (!opts)
continue;
null_endofword(opts);
for (p = strtok_r(opts, ",", &saveptr); p;
p = strtok_r(NULL, ",", &saveptr)) {
if (strcmp(p, "ro") == 0)
flags |= MS_RDONLY;
else if (strcmp(p, "nodev") == 0)
flags |= MS_NODEV;
else if (strcmp(p, "nosuid") == 0)
flags |= MS_NOSUID;
else if (strcmp(p, "noexec") == 0)
flags |= MS_NOEXEC;
/* XXX todo - we'll have to deal with atime? */
}
}
free(line);
fclose(f);
return flags;
}
static int mount_entry(const char *fsname, const char *target,
const char *fstype, unsigned long mountflags,
const char *data, int optional)
{
unsigned long extraflags;
struct statvfs sb;
if (mount(fsname, target, fstype, mountflags & ~MS_REMOUNT, data)) {
if (optional) {
INFO("failed to mount '%s' on '%s' (optional): %s", fsname,
@ -2008,20 +1972,34 @@ static int mount_entry(const char *fsname, const char *target,
}
if ((mountflags & MS_REMOUNT) || (mountflags & MS_BIND)) {
extraflags = get_mount_flags(target);
DEBUG("flags was %lu, extraflags set to %lu", mountflags, extraflags);
if (!(mountflags & MS_REMOUNT) && (mountflags & MS_BIND)) {
if (!(extraflags & ~mountflags))
DEBUG("all mount flags match, skipping remount");
goto skipremount;
}
mountflags |= extraflags;
}
DEBUG("remounting %s on %s to respect bind or remount options",
fsname ? fsname : "(none)", target ? target : "(none)");
if ((mountflags & MS_REMOUNT) || (mountflags & MS_BIND)) {
DEBUG("remounting %s on %s to respect bind or remount options %lu (extra %lu)",
fsname ? fsname : "(none)",
target ? target : "(none)", mountflags, extraflags);
if (statvfs(fsname, &sb) == 0) {
unsigned long required_flags = 0;
if (sb.f_flag & MS_NOSUID)
required_flags |= MS_NOSUID;
if (sb.f_flag & MS_NODEV)
required_flags |= MS_NODEV;
if (sb.f_flag & MS_RDONLY)
required_flags |= MS_RDONLY;
if (sb.f_flag & MS_NOEXEC)
required_flags |= MS_NOEXEC;
DEBUG("(at remount) flags for %s was %lu, required extra flags are %lu", fsname, sb.f_flag, required_flags);
/*
* If this was a bind mount request, and required_flags
* does not have any flags which are not already in
* mountflags, then skip the remount
*/
if (!(mountflags & MS_REMOUNT)) {
if (!(required_flags & ~mountflags)) {
DEBUG("mountflags already was %lu, skipping remount",
mountflags);
goto skipremount;
}
}
mountflags |= required_flags;
}
if (mount(fsname, target, fstype,
mountflags | MS_REMOUNT, data)) {