In commit 57cfe29e69 ("btrfs-progs: utils: introduce
find_mount_fsroot") the entries in /proc/self/mountinfo are parsed by a
convenience library libmount, because getmntent does not provide the
information we need to distinguish bind mounts.
Using libmount turned out to be problematic in several ways:
- static build got broken due to clashing symbols, eg. for parsing size
or path canonicalization (#333)
- long-term distros do not have libmount new enough (2.24+) to provide
some functions (mnt_table_is_empty, #334)
- libmount internally uses getgrnam_r/mnt_get_uid/... that are not
static-build friendly, a warning is printed during link time for each
binary; we don't use any of the functions
- libmount has further library dependencies that we don't need:
$ ldd /usr/lib64/libmount.so.1
linux-vdso.so.1 (0x00007fff4f175000)
libc.so.6 => /lib64/libc.so.6 (0x00007f44a1763000)
libblkid.so.1 => /usr/lib64/libblkid.so.1 (0x00007f44a1730000)
libselinux.so.1 => /usr/lib64/libselinux.so.1 (0x00007f44a1704000)
/lib64/ld-linux-x86-64.so.2 (0x00007f44a1998000)
libpcre.so.1 => /usr/lib64/libpcre.so.1 (0x00007f44a166c000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f44a1666000)
namely selinux, pcre and dl.
Summing it up, libmount causes more trouble than it's worth using a
convenience library, we want to keep the dependencies minimal so the
custom mountinfo parser was inevitable.
Issue: #333
Issue: #334
Issue: #336
Signed-off-by: David Sterba <dsterba@suse.com>
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