From f94f70d39cc2d54079ebae934862198516315db2 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 27 Oct 2023 11:42:57 +0100 Subject: afs: Provide a way to configure address priorities AFS servers may have multiple addresses, but the client can't easily judge between them as to which one is best. For instance, an address that has a larger RTT might actually have a better bandwidth because it goes through a switch rather than being directly connected - but we can't work this out dynamically unless we push through sufficient data that we can measure it. To allow the administrator to configure this, add a list of preference weightings for server addresses by IPv4/IPv6 address or subnet and allow this to be viewed through a procfile and altered by writing text commands to that same file. Preference rules can be added/updated by: echo "add [/] " >/proc/fs/afs/addr_prefs echo "add udp 1.2.3.4 1000" >/proc/fs/afs/addr_prefs echo "add udp 192.168.0.0/16 3000" >/proc/fs/afs/addr_prefs echo "add udp 1001:2002:0:6::/64 4000" >/proc/fs/afs/addr_prefs and removed by: echo "del [/]" >/proc/fs/afs/addr_prefs echo "del udp 1.2.3.4" >/proc/fs/afs/addr_prefs where the priority is a number between 0 and 65535. The list is split between IPv4 and IPv6 addresses and each sublist is kept in numerical order, with rules that would otherwise match but have different subnet masking being ordered with the most specific submatch first. A subsequent patch will apply these rules. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org --- fs/afs/proc.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 54 insertions(+), 1 deletion(-) (limited to 'fs/afs/proc.c') diff --git a/fs/afs/proc.c b/fs/afs/proc.c index 0b43bb9b0260..2e63c99a4f1e 100644 --- a/fs/afs/proc.c +++ b/fs/afs/proc.c @@ -146,6 +146,55 @@ inval: goto done; } +/* + * Display the list of addr_prefs known to the namespace. + */ +static int afs_proc_addr_prefs_show(struct seq_file *m, void *v) +{ + struct afs_addr_preference_list *preflist; + struct afs_addr_preference *pref; + struct afs_net *net = afs_seq2net_single(m); + union { + struct sockaddr_in sin; + struct sockaddr_in6 sin6; + } addr; + unsigned int i; + char buf[44]; /* Maximum ipv6 + max subnet is 43 */ + + rcu_read_lock(); + preflist = rcu_dereference(net->address_prefs); + + if (!preflist) { + seq_puts(m, "NO PREFS\n"); + return 0; + } + + seq_printf(m, "PROT SUBNET PRIOR (v=%u n=%u/%u/%u)\n", + preflist->version, preflist->ipv6_off, preflist->nr, preflist->max_prefs); + + memset(&addr, 0, sizeof(addr)); + + for (i = 0; i < preflist->nr; i++) { + pref = &preflist->prefs[i]; + + addr.sin.sin_family = pref->family; + if (pref->family == AF_INET) { + memcpy(&addr.sin.sin_addr, &pref->ipv4_addr, + sizeof(addr.sin.sin_addr)); + snprintf(buf, sizeof(buf), "%pISc/%u", &addr.sin, pref->subnet_mask); + seq_printf(m, "UDP %-43.43s %5u\n", buf, pref->prio); + } else { + memcpy(&addr.sin6.sin6_addr, &pref->ipv6_addr, + sizeof(addr.sin6.sin6_addr)); + snprintf(buf, sizeof(buf), "%pISc/%u", &addr.sin6, pref->subnet_mask); + seq_printf(m, "UDP %-43.43s %5u\n", buf, pref->prio); + } + } + + rcu_read_lock(); + return 0; +} + /* * Display the name of the current workstation cell. */ @@ -690,7 +739,11 @@ int afs_proc_init(struct afs_net *net) &afs_proc_sysname_ops, afs_proc_sysname_write, sizeof(struct seq_net_private), - NULL)) + NULL) || + !proc_create_net_single_write("addr_prefs", 0644, p, + afs_proc_addr_prefs_show, + afs_proc_addr_prefs_write, + NULL)) goto error_tree; net->proc_afs = p; -- cgit v1.2.3-58-ga151