Sometimes we cannot restore route entries, because in kernel
[1] fib_check_nh()
[2] fib_valid_prefsrc()
cause some routes to depend on existence of others while adding.
For example, we saved all the routes, and flushed all tables
[a] default via 192.168.122.1 dev eth0
[b] 192.168.122.0/24 dev eth0 src 192.168.122.21
[c] broadcast 127.0.0.0 dev lo table local src 127.0.0.1
[d] local 127.0.0.0/8 dev lo table local src 127.0.0.1
[e] local 127.0.0.1 dev lo table local src 127.0.0.1
[f] broadcast 127.255.255.255 dev lo table local src 127.0.0.1
[g] broadcast 192.168.122.0 dev eth0 table local src 192.168.122.21
[h] local 192.168.122.21 dev eth0 table local src 192.168.122.21
[i] broadcast 192.168.122.255 dev eth0 table local src 192.168.122.21
Now start to restore them:
If we want to add [a], we have to add [b] first, as [1] and
'via 192.168.122.1' in [a].
If we want to add [b], we have to add [h] first, as [2] and
'src 192.168.122.21' in [b].
So the correct order to restore should be like:
[e][h] -> [b][c][d][f][g][i] -> [a]
This patch fixes it by traversing the file 3 times, it only restores
part of them in each run according to the following conditions, to
make sure every entry can be restored successfully.
1. !gw && (!fib_prefsrc || fib_prefsrc == cfg->fc_dst)
2. !gw && (fib_prefsrc != cfg->fc_dst)
3. gw
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Phil Sutter <phil@nwl.cc>
74af8dd962