On Thu, Jan 30, 2020 at 03:45:20PM +0100, Christian Brauner wrote: > > - nd->total_link_count++; > > - if (nd->total_link_count >= 40) > > + if (count && *count++ >= 40) > > He, side-effects galore. :) > Isn't this incrementing the address but you want to increment the > counter? > Seems like this should be > > if (count && (*count)++ >= 40) Nice catch; incidentally, it means that usual testsuites (xfstests, LTP) are missing the automount loop detection. Hmm... Something like export $FOO over nfs4 to localhost mkdir $FOO/sub touch $FOO/a mount $SCRATCH_DEV $FOO/sub touch $FOO/sub/a cd $BAR mkdir nfs mount -t nfs localhost:$FOO nfs for i in `seq 40`; do ln -s l`expr $i - 1` l$i; done for i in `seq 40`; do ln -s m`expr $i - 1` m$i; done ln -s nfs/sub/a l0 ln -s nfs/a m0 for i in `seq 40`; do umount nfs/sub 2>/dev/null cat l$i m$i done BTW, the check of pre-increment value is more correct - it's accidental, but it does give consistency with the normal symlink following. We do allow up to 40 symlinks over the pathname resolution, not up to 39. The thing above should produce cat: l39: Too many levels of symbolic links cat: l40: Too many levels of symbolic links cat: m40: Too many levels of symbolic links Here l<n> and m<n> go through n + 1 symlink, ending at nfs/sub/a and nfs/a resp.; the former does trigger an automount, the latter does not. On mainline it actually starts to complain about l38, l39, l40 and m40, due to that off-by-one in follow_automount().
