NFSD: Traverse unconfirmed client through hash-table

When stopping nfsd, I got BUG messages, and soft lockup messages,
The problem is cuased by double rb_erase() in nfs4_state_destroy_net()
and destroy_client().

This patch just let nfsd traversing unconfirmed client through
hash-table instead of rbtree.

[ 2325.021995] BUG: unable to handle kernel NULL pointer dereference at
          (null)
[ 2325.022809] IP: [<ffffffff8133c18c>] rb_erase+0x14c/0x390
[ 2325.022982] PGD 7a91b067 PUD 7a33d067 PMD 0
[ 2325.022982] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
[ 2325.022982] Modules linked in: nfsd(OF) cfg80211 rfkill bridge stp
llc snd_intel8x0 snd_ac97_codec ac97_bus auth_rpcgss nfs_acl serio_raw
e1000 i2c_piix4 ppdev snd_pcm snd_timer lockd pcspkr joydev parport_pc
snd parport i2c_core soundcore microcode sunrpc ata_generic pata_acpi
[last unloaded: nfsd]
[ 2325.022982] CPU: 1 PID: 2123 Comm: nfsd Tainted: GF          O
3.14.0-rc8+ #2
[ 2325.022982] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[ 2325.022982] task: ffff88007b384800 ti: ffff8800797f6000 task.ti:
ffff8800797f6000
[ 2325.022982] RIP: 0010:[<ffffffff8133c18c>]  [<ffffffff8133c18c>]
rb_erase+0x14c/0x390
[ 2325.022982] RSP: 0018:ffff8800797f7d98  EFLAGS: 00010246
[ 2325.022982] RAX: ffff880079c1f010 RBX: ffff880079f4c828 RCX:
0000000000000000
[ 2325.022982] RDX: 0000000000000000 RSI: ffff880079bcb070 RDI:
ffff880079f4c810
[ 2325.022982] RBP: ffff8800797f7d98 R08: 0000000000000000 R09:
ffff88007964fc70
[ 2325.022982] R10: 0000000000000000 R11: 0000000000000400 R12:
ffff880079f4c800
[ 2325.022982] R13: ffff880079bcb000 R14: ffff8800797f7da8 R15:
ffff880079f4c860
[ 2325.022982] FS:  0000000000000000(0000) GS:ffff88007f900000(0000)
knlGS:0000000000000000
[ 2325.022982] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 2325.022982] CR2: 0000000000000000 CR3: 000000007a3ef000 CR4:
00000000000006e0
[ 2325.022982] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[ 2325.022982] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[ 2325.022982] Stack:
[ 2325.022982]  ffff8800797f7de0 ffffffffa0191c6e ffff8800797f7da8
ffff8800797f7da8
[ 2325.022982]  ffff880079f4c810 ffff880079bcb000 ffffffff81cc26c0
ffff880079c1f010
[ 2325.022982]  ffff880079bcb070 ffff8800797f7e28 ffffffffa01977f2
ffff8800797f7df0
[ 2325.022982] Call Trace:
[ 2325.022982]  [<ffffffffa0191c6e>] destroy_client+0x32e/0x3b0 [nfsd]
[ 2325.022982]  [<ffffffffa01977f2>] nfs4_state_shutdown_net+0x1a2/0x220
[nfsd]
[ 2325.022982]  [<ffffffffa01700b8>] nfsd_shutdown_net+0x38/0x70 [nfsd]
[ 2325.022982]  [<ffffffffa017013e>] nfsd_last_thread+0x4e/0x80 [nfsd]
[ 2325.022982]  [<ffffffffa001f1eb>] svc_shutdown_net+0x2b/0x30 [sunrpc]
[ 2325.022982]  [<ffffffffa017064b>] nfsd_destroy+0x5b/0x80 [nfsd]
[ 2325.022982]  [<ffffffffa0170773>] nfsd+0x103/0x130 [nfsd]
[ 2325.022982]  [<ffffffffa0170670>] ? nfsd_destroy+0x80/0x80 [nfsd]
[ 2325.022982]  [<ffffffff810a8232>] kthread+0xd2/0xf0
[ 2325.022982]  [<ffffffff810a8160>] ? insert_kthread_work+0x40/0x40
[ 2325.022982]  [<ffffffff816c493c>] ret_from_fork+0x7c/0xb0
[ 2325.022982]  [<ffffffff810a8160>] ? insert_kthread_work+0x40/0x40
[ 2325.022982] Code: 48 83 e1 fc 48 89 10 0f 84 02 01 00 00 48 3b 41 10
0f 84 08 01 00 00 48 89 51 08 48 89 fa e9 74 ff ff ff 0f 1f 40 00 48 8b
50 10 <f6> 02 01 0f 84 93 00 00 00 48 8b 7a 10 48 85 ff 74 05 f6 07 01
[ 2325.022982] RIP  [<ffffffff8133c18c>] rb_erase+0x14c/0x390
[ 2325.022982]  RSP <ffff8800797f7d98>
[ 2325.022982] CR2: 0000000000000000
[ 2325.022982] ---[ end trace 28c27ed011655e57 ]---

[  228.064071] BUG: soft lockup - CPU#0 stuck for 22s! [nfsd:558]
[  228.064428] Modules linked in: ip6t_rpfilter ip6t_REJECT cfg80211
xt_conntrack rfkill ebtable_nat ebtable_broute bridge stp llc
ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6
nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw
ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4
nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security
iptable_raw nfsd(OF) auth_rpcgss nfs_acl lockd snd_intel8x0
snd_ac97_codec ac97_bus joydev snd_pcm snd_timer e1000 sunrpc snd ppdev
parport_pc serio_raw pcspkr i2c_piix4 microcode parport soundcore
i2c_core ata_generic pata_acpi
[  228.064539] CPU: 0 PID: 558 Comm: nfsd Tainted: GF          O
3.14.0-rc8+ #2
[  228.064539] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[  228.064539] task: ffff880076adec00 ti: ffff880074616000 task.ti:
ffff880074616000
[  228.064539] RIP: 0010:[<ffffffff8133ba17>]  [<ffffffff8133ba17>]
rb_next+0x27/0x50
[  228.064539] RSP: 0018:ffff880074617de0  EFLAGS: 00000282
[  228.064539] RAX: ffff880074478010 RBX: ffff88007446f860 RCX:
0000000000000014
[  228.064539] RDX: ffff880074478010 RSI: 0000000000000000 RDI:
ffff880074478010
[  228.064539] RBP: ffff880074617de0 R08: 0000000000000000 R09:
0000000000000012
[  228.064539] R10: 0000000000000001 R11: ffffffffffffffec R12:
ffffea0001d11a00
[  228.064539] R13: ffff88007f401400 R14: ffff88007446f800 R15:
ffff880074617d50
[  228.064539] FS:  0000000000000000(0000) GS:ffff88007f800000(0000)
knlGS:0000000000000000
[  228.064539] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  228.064539] CR2: 00007fe9ac6ec000 CR3: 000000007a5d6000 CR4:
00000000000006f0
[  228.064539] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[  228.064539] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[  228.064539] Stack:
[  228.064539]  ffff880074617e28 ffffffffa01ab7db ffff880074617df0
ffff880074617df0
[  228.064539]  ffff880079273000 ffffffff81cc26c0 ffffffff81cc26c0
0000000000000000
[  228.064539]  0000000000000000 ffff880074617e48 ffffffffa01840b8
ffffffff81cc26c0
[  228.064539] Call Trace:
[  228.064539]  [<ffffffffa01ab7db>] nfs4_state_shutdown_net+0x18b/0x220
[nfsd]
[  228.064539]  [<ffffffffa01840b8>] nfsd_shutdown_net+0x38/0x70 [nfsd]
[  228.064539]  [<ffffffffa018413e>] nfsd_last_thread+0x4e/0x80 [nfsd]
[  228.064539]  [<ffffffffa00aa1eb>] svc_shutdown_net+0x2b/0x30 [sunrpc]
[  228.064539]  [<ffffffffa018464b>] nfsd_destroy+0x5b/0x80 [nfsd]
[  228.064539]  [<ffffffffa0184773>] nfsd+0x103/0x130 [nfsd]
[  228.064539]  [<ffffffffa0184670>] ? nfsd_destroy+0x80/0x80 [nfsd]
[  228.064539]  [<ffffffff810a8232>] kthread+0xd2/0xf0
[  228.064539]  [<ffffffff810a8160>] ? insert_kthread_work+0x40/0x40
[  228.064539]  [<ffffffff816c493c>] ret_from_fork+0x7c/0xb0
[  228.064539]  [<ffffffff810a8160>] ? insert_kthread_work+0x40/0x40
[  228.064539] Code: 1f 44 00 00 55 48 8b 17 48 89 e5 48 39 d7 74 3b 48
8b 47 08 48 85 c0 75 0e eb 25 66 0f 1f 84 00 00 00 00 00 48 89 d0 48 8b
50 10 <48> 85 d2 75 f4 5d c3 66 90 48 3b 78 08 75 f6 48 8b 10 48 89 c7

Fixes: ac55fdc408039 (nfsd: move the confirmed and unconfirmed hlists...)
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -5062,7 +5062,6 @@ nfs4_state_destroy_net(struct net *net)
 	int i;
 	struct nfs4_client *clp = NULL;
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
-	struct rb_node *node, *tmp;
 
 	for (i = 0; i < CLIENT_HASH_SIZE; i++) {
 		while (!list_empty(&nn->conf_id_hashtbl[i])) {
@@ -5071,13 +5070,11 @@ nfs4_state_destroy_net(struct net *net)
 		}
 	}
 
-	node = rb_first(&nn->unconf_name_tree);
-	while (node != NULL) {
-		tmp = node;
-		node = rb_next(tmp);
-		clp = rb_entry(tmp, struct nfs4_client, cl_namenode);
-		rb_erase(tmp, &nn->unconf_name_tree);
-		destroy_client(clp);
+	for (i = 0; i < CLIENT_HASH_SIZE; i++) {
+		while (!list_empty(&nn->unconf_id_hashtbl[i])) {
+			clp = list_entry(nn->unconf_id_hashtbl[i].next, struct nfs4_client, cl_idhash);
+			destroy_client(clp);
+		}
 	}
 
 	kfree(nn->sessionid_hashtbl);