Merge tag 'afs-fix-rotation-20240105' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull afs updates from David Howells:
 "The majority of the patches are aimed at fixing and improving the AFS
  filesystem's rotation over server IP addresses, but there are also
  some fixes from Oleg Nesterov for the use of read_seqbegin_or_lock().

   - Fix fileserver probe handling so that the next round of probes
     doesn't break ongoing server/address rotation by clearing all the
     probe result tracking. This could occasionally cause the rotation
     algorithm to drop straight through, give a 'successful' result
     without actually emitting any RPC calls, leaving the reply buffer
     in an undefined state.

     Instead, detach the probe results into a separate struct and
     allocate a new one each time we start probing and update the
     pointer to it. Probes are also sent in order of address preference
     to try and improve the chance that the preferred one will complete
     first.

   - Fix server rotation so that it uses configurable address
     preferences across on the probes that have completed so far than
     ranking them by RTT as the latter doesn't necessarily give the best
     route. The preference list can be altered by writing into
     /proc/net/afs/addr_prefs.

   - Fix the handling of Read-Only (and Backup) volume callbacks as
     there is one per volume, not one per file, so if someone performs a
     command that, say, offlines the volume but doesn't change it, when
     it comes back online we don't spam the server with a status fetch
     for every vnode we're using. Instead, check the Creation timestamp
     in the VolSync record when prompted by a callback break.

   - Handle volume regression (ie. a RW volume being restored from a
     backup) by scrubbing all cache data for that volume. This is
     detected from the VolSync creation timestamp.

   - Adjust abort handling and abort -> error mapping to match better
     with what other AFS clients do.

   - Fix offline and busy volume state handling as they only apply to
     individual server instances and not entire volumes and the rotation
     algorithm should go and look at other servers if available. Also
     make it sleep briefly before each retry if all the volume instances
     are unavailable"

* tag 'afs-fix-rotation-20240105' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: (40 commits)
  afs: trace: Log afs_make_call(), including server address
  afs: Fix offline and busy message emission
  afs: Fix fileserver rotation
  afs: Overhaul invalidation handling to better support RO volumes
  afs: Parse the VolSync record in the reply of a number of RPC ops
  afs: Don't leave DONTUSE/NEWREPSITE servers out of server list
  afs: Fix comment in afs_do_lookup()
  afs: Apply server breaks to mmap'd files in the call processor
  afs: Move the vnode/volume validity checking code into its own file
  afs: Defer volume record destruction to a workqueue
  afs: Make it possible to find the volumes that are using a server
  afs: Combine the endpoint state bools into a bitmask
  afs: Keep a record of the current fileserver endpoint state
  afs: Dispatch vlserver probes in priority order
  afs: Dispatch fileserver probes in priority order
  afs: Mark address lists with configured priorities
  afs: Provide a way to configure address priorities
  afs: Remove the unimplemented afs_cmp_addr_list()
  afs: Add some more info to /proc/net/afs/servers
  rxrpc: Create a procfile to display outstanding client conn bundles
  ...

Author: torvalds

fs/afs/Makefile

@@ -5,6 +5,7 @@
 
 kafs-y := \
 	addr_list.o \
+	addr_prefs.o \
 	callback.o \
 	cell.o \
 	cmservice.o \
@@ -27,6 +28,7 @@ kafs-y := \
 	server.o \
 	server_list.o \
 	super.o \
+	validation.o \
 	vlclient.o \
 	vl_alias.o \
 	vl_list.o \

fs/afs/addr_list.c

@@ -13,26 +13,55 @@
 #include "internal.h"
 #include "afs_fs.h"
 
+static void afs_free_addrlist(struct rcu_head *rcu)
+{
+	struct afs_addr_list *alist = container_of(rcu, struct afs_addr_list, rcu);
+	unsigned int i;
+
+	for (i = 0; i < alist->nr_addrs; i++)
+		rxrpc_kernel_put_peer(alist->addrs[i].peer);
+	trace_afs_alist(alist->debug_id, refcount_read(&alist->usage), afs_alist_trace_free);
+	kfree(alist);
+}
+
 /*
  * Release an address list.
  */
-void afs_put_addrlist(struct afs_addr_list *alist)
+void afs_put_addrlist(struct afs_addr_list *alist, enum afs_alist_trace reason)
+{
+	unsigned int debug_id;
+	bool dead;
+	int r;
+
+	if (!alist)
+		return;
+	debug_id = alist->debug_id;
+	dead = __refcount_dec_and_test(&alist->usage, &r);
+	trace_afs_alist(debug_id, r - 1, reason);
+	if (dead)
+		call_rcu(&alist->rcu, afs_free_addrlist);
+}
+
+struct afs_addr_list *afs_get_addrlist(struct afs_addr_list *alist, enum afs_alist_trace reason)
 {
-	if (alist && refcount_dec_and_test(&alist->usage))
-		kfree_rcu(alist, rcu);
+	int r;
+
+	if (alist) {
+		__refcount_inc(&alist->usage, &r);
+		trace_afs_alist(alist->debug_id, r + 1, reason);
+	}
+	return alist;
 }
 
 /*
  * Allocate an address list.
  */
-struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
-					 unsigned short service,
-					 unsigned short port)
+struct afs_addr_list *afs_alloc_addrlist(unsigned int nr)
 {
 	struct afs_addr_list *alist;
-	unsigned int i;
+	static atomic_t debug_id;
 
-	_enter("%u,%u,%u", nr, service, port);
+	_enter("%u", nr);
 
 	if (nr > AFS_MAX_ADDRESSES)
 		nr = AFS_MAX_ADDRESSES;
@@ -43,17 +72,8 @@ struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
 
 	refcount_set(&alist->usage, 1);
 	alist->max_addrs = nr;
-
-	for (i = 0; i < nr; i++) {
-		struct sockaddr_rxrpc *srx = &alist->addrs[i];
-		srx->srx_family			= AF_RXRPC;
-		srx->srx_service		= service;
-		srx->transport_type		= SOCK_DGRAM;
-		srx->transport_len		= sizeof(srx->transport.sin6);
-		srx->transport.sin6.sin6_family	= AF_INET6;
-		srx->transport.sin6.sin6_port	= htons(port);
-	}
-
+	alist->debug_id = atomic_inc_return(&debug_id);
+	trace_afs_alist(alist->debug_id, 1, afs_alist_trace_alloc);
 	return alist;
 }
 
@@ -126,7 +146,7 @@ struct afs_vlserver_list *afs_parse_text_addrs(struct afs_net *net,
 	if (!vllist->servers[0].server)
 		goto error_vl;
 
-	alist = afs_alloc_addrlist(nr, service, AFS_VL_PORT);
+	alist = afs_alloc_addrlist(nr);
 	if (!alist)
 		goto error;
 
@@ -197,9 +217,11 @@ struct afs_vlserver_list *afs_parse_text_addrs(struct afs_net *net,
 		}
 
 		if (family == AF_INET)
-			afs_merge_fs_addr4(alist, x[0], xport);
+			ret = afs_merge_fs_addr4(net, alist, x[0], xport);
 		else
-			afs_merge_fs_addr6(alist, x, xport);
+			ret = afs_merge_fs_addr6(net, alist, x, xport);
+		if (ret < 0)
+			goto error;
 
 	} while (p < end);
 
@@ -216,25 +238,12 @@ struct afs_vlserver_list *afs_parse_text_addrs(struct afs_net *net,
 	       problem, p - text, (int)len, (int)len, text);
 	ret = -EINVAL;
 error:
-	afs_put_addrlist(alist);
+	afs_put_addrlist(alist, afs_alist_trace_put_parse_error);
 error_vl:
 	afs_put_vlserverlist(net, vllist);
 	return ERR_PTR(ret);
 }
 
-/*
- * Compare old and new address lists to see if there's been any change.
- * - How to do this in better than O(Nlog(N)) time?
- *   - We don't really want to sort the address list, but would rather take the
- *     list as we got it so as not to undo record rotation by the DNS server.
- */
-#if 0
-static int afs_cmp_addr_list(const struct afs_addr_list *a1,
-			     const struct afs_addr_list *a2)
-{
-}
-#endif
-
 /*
  * Perform a DNS query for VL servers and build a up an address list.
  */
@@ -271,25 +280,33 @@ struct afs_vlserver_list *afs_dns_query(struct afs_cell *cell, time64_t *_expiry
 /*
  * Merge an IPv4 entry into a fileserver address list.
  */
-void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
+int afs_merge_fs_addr4(struct afs_net *net, struct afs_addr_list *alist,
+		       __be32 xdr, u16 port)
 {
-	struct sockaddr_rxrpc *srx;
-	u32 addr = ntohl(xdr);
+	struct sockaddr_rxrpc srx;
+	struct rxrpc_peer *peer;
 	int i;
 
 	if (alist->nr_addrs >= alist->max_addrs)
-		return;
+		return 0;
 
-	for (i = 0; i < alist->nr_ipv4; i++) {
-		struct sockaddr_in *a = &alist->addrs[i].transport.sin;
-		u32 a_addr = ntohl(a->sin_addr.s_addr);
-		u16 a_port = ntohs(a->sin_port);
+	srx.srx_family = AF_RXRPC;
+	srx.transport_type = SOCK_DGRAM;
+	srx.transport_len = sizeof(srx.transport.sin);
+	srx.transport.sin.sin_family = AF_INET;
+	srx.transport.sin.sin_port = htons(port);
+	srx.transport.sin.sin_addr.s_addr = xdr;
 
-		if (addr == a_addr && port == a_port)
-			return;
-		if (addr == a_addr && port < a_port)
-			break;
-		if (addr < a_addr)
+	peer = rxrpc_kernel_lookup_peer(net->socket, &srx, GFP_KERNEL);
+	if (!peer)
+		return -ENOMEM;
+
+	for (i = 0; i < alist->nr_ipv4; i++) {
+		if (peer == alist->addrs[i].peer) {
+			rxrpc_kernel_put_peer(peer);
+			return 0;
+		}
+		if (peer <= alist->addrs[i].peer)
 			break;
 	}
 
@@ -298,107 +315,50 @@ void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
 			alist->addrs + i,
 			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
 
-	srx = &alist->addrs[i];
-	srx->srx_family = AF_RXRPC;
-	srx->transport_type = SOCK_DGRAM;
-	srx->transport_len = sizeof(srx->transport.sin);
-	srx->transport.sin.sin_family = AF_INET;
-	srx->transport.sin.sin_port = htons(port);
-	srx->transport.sin.sin_addr.s_addr = xdr;
+	alist->addrs[i].peer = peer;
 	alist->nr_ipv4++;
 	alist->nr_addrs++;
+	return 0;
 }
 
 /*
  * Merge an IPv6 entry into a fileserver address list.
  */
-void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
+int afs_merge_fs_addr6(struct afs_net *net, struct afs_addr_list *alist,
+		       __be32 *xdr, u16 port)
 {
-	struct sockaddr_rxrpc *srx;
-	int i, diff;
+	struct sockaddr_rxrpc srx;
+	struct rxrpc_peer *peer;
+	int i;
 
 	if (alist->nr_addrs >= alist->max_addrs)
-		return;
+		return 0;
 
-	for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
-		struct sockaddr_in6 *a = &alist->addrs[i].transport.sin6;
-		u16 a_port = ntohs(a->sin6_port);
+	srx.srx_family = AF_RXRPC;
+	srx.transport_type = SOCK_DGRAM;
+	srx.transport_len = sizeof(srx.transport.sin6);
+	srx.transport.sin6.sin6_family = AF_INET6;
+	srx.transport.sin6.sin6_port = htons(port);
+	memcpy(&srx.transport.sin6.sin6_addr, xdr, 16);
 
-		diff = memcmp(xdr, &a->sin6_addr, 16);
-		if (diff == 0 && port == a_port)
-			return;
-		if (diff == 0 && port < a_port)
-			break;
-		if (diff < 0)
+	peer = rxrpc_kernel_lookup_peer(net->socket, &srx, GFP_KERNEL);
+	if (!peer)
+		return -ENOMEM;
+
+	for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
+		if (peer == alist->addrs[i].peer) {
+			rxrpc_kernel_put_peer(peer);
+			return 0;
+		}
+		if (peer <= alist->addrs[i].peer)
 			break;
 	}
 
 	if (i < alist->nr_addrs)
 		memmove(alist->addrs + i + 1,
 			alist->addrs + i,
 			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));
-
-	srx = &alist->addrs[i];
-	srx->srx_family = AF_RXRPC;
-	srx->transport_type = SOCK_DGRAM;
-	srx->transport_len = sizeof(srx->transport.sin6);
-	srx->transport.sin6.sin6_family = AF_INET6;
-	srx->transport.sin6.sin6_port = htons(port);
-	memcpy(&srx->transport.sin6.sin6_addr, xdr, 16);
+	alist->addrs[i].peer = peer;
 	alist->nr_addrs++;
-}
-
-/*
- * Get an address to try.
- */
-bool afs_iterate_addresses(struct afs_addr_cursor *ac)
-{
-	unsigned long set, failed;
-	int index;
-
-	if (!ac->alist)
-		return false;
-
-	set = ac->alist->responded;
-	failed = ac->alist->failed;
-	_enter("%lx-%lx-%lx,%d", set, failed, ac->tried, ac->index);
-
-	ac->nr_iterations++;
-
-	set &= ~(failed | ac->tried);
-
-	if (!set)
-		return false;
-
-	index = READ_ONCE(ac->alist->preferred);
-	if (test_bit(index, &set))
-		goto selected;
-
-	index = __ffs(set);
-
-selected:
-	ac->index = index;
-	set_bit(index, &ac->tried);
-	ac->responded = false;
-	return true;
-}
-
-/*
- * Release an address list cursor.
- */
-int afs_end_cursor(struct afs_addr_cursor *ac)
-{
-	struct afs_addr_list *alist;
-
-	alist = ac->alist;
-	if (alist) {
-		if (ac->responded &&
-		    ac->index != alist->preferred &&
-		    test_bit(ac->alist->preferred, &ac->tried))
-			WRITE_ONCE(alist->preferred, ac->index);
-		afs_put_addrlist(alist);
-		ac->alist = NULL;
-	}
-
-	return ac->error;
+	return 0;
 }