mnt: remount all filesystems

Explicitly specifying RW "/" mount in config did not yield desired
result.
The reason was a default RO "/" tmpfs is prepended to mountpoint
list. All filesystems are initially mounted RW to be able to create
directories for mountpoints. Read only filesystems were remounted
during a 2nd pass, effectively overriding RW flag of fs mounted
over them.

Fixes #88

diff --git a/mnt.cc b/mnt.cc
index a58b93c..a019df5 100644 (file)
--- a/mnt.cc
+++ b/mnt.cc
@@ -220,16 +220,13 @@ static bool mountPt(mount_t* mpt, const char* newroot, const char* tmpdir) {
        return true;
 }
 
-static bool remountRO(const mount_t& mpt) {
+static bool remount(const mount_t& mpt) {
        if (!mpt.mounted) {
                return true;
        }
        if (mpt.is_symlink) {
                return true;
        }
-       if ((mpt.flags & MS_RDONLY) == 0) {
-               return true;
-       }
 
        struct statvfs vfs;
        if (TEMP_FAILURE_RETRY(statvfs(mpt.dst.c_str(), &vfs)) == -1) {
@@ -241,7 +238,6 @@ static bool remountRO(const mount_t& mpt) {
                const unsigned long mount_flag;
                const unsigned long vfs_flag;
        } static const mountPairs[] = {
-           {MS_RDONLY, ST_RDONLY},
            {MS_NOSUID, ST_NOSUID},
            {MS_NODEV, ST_NODEV},
            {MS_NOEXEC, ST_NOEXEC},
@@ -252,14 +248,14 @@ static bool remountRO(const mount_t& mpt) {
            {MS_RELATIME, ST_RELATIME},
        };
 
-       unsigned long new_flags = MS_REMOUNT | MS_RDONLY | MS_BIND;
+       unsigned long new_flags = MS_REMOUNT | MS_BIND | (mpt.flags & MS_RDONLY);
        for (const auto& i : mountPairs) {
                if (vfs.f_flag & i.vfs_flag) {
                        new_flags |= i.mount_flag;
                }
        }
 
-       LOG_D("Re-mounting R/O '%s' (flags:%s)", mpt.dst.c_str(), flagsToStr(new_flags).c_str());
+       LOG_D("Re-mounting '%s' (flags:%s)", mpt.dst.c_str(), flagsToStr(new_flags).c_str());
        if (mount(mpt.dst.c_str(), mpt.dst.c_str(), NULL, new_flags, 0) == -1) {
                PLOG_W("mount('%s', flags:%s)", mpt.dst.c_str(), flagsToStr(new_flags).c_str());
                return false;
@@ -418,7 +414,7 @@ static bool initNsInternal(nsjconf_t* nsjconf) {
        }
 
        for (const auto& p : nsjconf->mountpts) {
-               if (!remountRO(p) && p.is_mandatory) {
+               if (!remount(p) && p.is_mandatory) {
                        return false;
                }
        }