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From: David Howells <dhowells@redhat.com>
To: linux-afs@lists.infradead.org
Cc: Jeffrey Altman <jaltman@auristor.com>,
	dhowells@redhat.com, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 05/27] afs: Use the serverUnique field in the UVLDB record to reduce rpc ops
Date: Fri, 29 May 2020 23:00:42 +0100	[thread overview]
Message-ID: <159078964223.679399.3725226162754750915.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <159078959973.679399.15496997680826127470.stgit@warthog.procyon.org.uk>

The U-version VLDB volume record retrieved by the VL.GetEntryByNameU rpc op
carries a change counter (the serverUnique field) for each fileserver
listed in the record as backing that volume.  This is incremented whenever
the registration details for a fileserver change (such as its address
list).  Note that the same value will be seen in all UVLDB records that
refer to that fileserver.

This should be checked before calling the VL server to re-query the address
list for a fileserver.  If it's the same, there's no point doing the query.

Reported-by: Jeffrey Altman <jaltman@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/internal.h    |    5 +++--
 fs/afs/server.c      |   26 ++++++++++++++------------
 fs/afs/server_list.c |    3 ++-
 fs/afs/vlclient.c    |    1 +
 4 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 80255513e230..ee17c868ad2c 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -471,6 +471,7 @@ struct afs_vldb_entry {
 #define AFS_VLDB_QUERY_ERROR	4		/* - VL server returned error */
 
 	uuid_t			fs_server[AFS_NMAXNSERVERS];
+	u32			addr_version[AFS_NMAXNSERVERS]; /* Registration change counters */
 	u8			fs_mask[AFS_NMAXNSERVERS];
 #define AFS_VOL_VTM_RW	0x01 /* R/W version of the volume is available (on this server) */
 #define AFS_VOL_VTM_RO	0x02 /* R/O version of the volume is available (on this server) */
@@ -498,7 +499,6 @@ struct afs_server {
 	struct hlist_node	proc_link;	/* Link in net->fs_proc */
 	struct afs_server	*gc_next;	/* Next server in manager's list */
 	time64_t		put_time;	/* Time at which last put */
-	time64_t		update_at;	/* Time at which to next update the record */
 	unsigned long		flags;
 #define AFS_SERVER_FL_NOT_READY	1		/* The record is not ready for use */
 #define AFS_SERVER_FL_NOT_FOUND	2		/* VL server says no such server */
@@ -511,6 +511,7 @@ struct afs_server {
 #define AFS_SERVER_FL_IS_YFS	9		/* Server is YFS not AFS */
 #define AFS_SERVER_FL_NO_RM2	10		/* Fileserver doesn't support YFS.RemoveFile2 */
 #define AFS_SERVER_FL_HAVE_EPOCH 11		/* ->epoch is valid */
+#define AFS_SERVER_FL_NEEDS_UPDATE 12		/* Fileserver address list is out of date */
 	atomic_t		usage;
 	u32			addr_version;	/* Address list version */
 	u32			cm_epoch;	/* Server RxRPC epoch */
@@ -1241,7 +1242,7 @@ extern spinlock_t afs_server_peer_lock;
 extern struct afs_server *afs_find_server(struct afs_net *,
 					  const struct sockaddr_rxrpc *);
 extern struct afs_server *afs_find_server_by_uuid(struct afs_net *, const uuid_t *);
-extern struct afs_server *afs_lookup_server(struct afs_cell *, struct key *, const uuid_t *);
+extern struct afs_server *afs_lookup_server(struct afs_cell *, struct key *, const uuid_t *, u32);
 extern struct afs_server *afs_get_server(struct afs_server *, enum afs_server_trace);
 extern void afs_put_server(struct afs_net *, struct afs_server *, enum afs_server_trace);
 extern void afs_manage_servers(struct work_struct *);
diff --git a/fs/afs/server.c b/fs/afs/server.c
index 11b90ac7ea30..9e50ccde5d37 100644
--- a/fs/afs/server.c
+++ b/fs/afs/server.c
@@ -12,7 +12,6 @@
 #include "protocol_yfs.h"
 
 static unsigned afs_server_gc_delay = 10;	/* Server record timeout in seconds */
-static unsigned afs_server_update_delay = 30;	/* Time till VLDB recheck in secs */
 static atomic_t afs_server_debug_id;
 
 static void afs_inc_servers_outstanding(struct afs_net *net)
@@ -218,7 +217,6 @@ static struct afs_server *afs_alloc_server(struct afs_net *net,
 	RCU_INIT_POINTER(server->addresses, alist);
 	server->addr_version = alist->version;
 	server->uuid = *uuid;
-	server->update_at = ktime_get_real_seconds() + afs_server_update_delay;
 	rwlock_init(&server->fs_lock);
 	INIT_HLIST_HEAD(&server->cb_volumes);
 	rwlock_init(&server->cb_break_lock);
@@ -264,7 +262,7 @@ static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell,
  * Get or create a fileserver record.
  */
 struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
-				     const uuid_t *uuid)
+				     const uuid_t *uuid, u32 addr_version)
 {
 	struct afs_addr_list *alist;
 	struct afs_server *server, *candidate;
@@ -272,8 +270,11 @@ struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
 	_enter("%p,%pU", cell->net, uuid);
 
 	server = afs_find_server_by_uuid(cell->net, uuid);
-	if (server)
+	if (server) {
+		if (server->addr_version != addr_version)
+			set_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
 		return server;
+	}
 
 	alist = afs_vl_lookup_addrs(cell, key, uuid);
 	if (IS_ERR(alist))
@@ -558,7 +559,6 @@ static noinline bool afs_update_server_record(struct afs_fs_cursor *fc, struct a
 		write_unlock(&server->fs_lock);
 	}
 
-	server->update_at = ktime_get_real_seconds() + afs_server_update_delay;
 	afs_put_addrlist(discard);
 	_leave(" = t");
 	return true;
@@ -569,8 +569,6 @@ static noinline bool afs_update_server_record(struct afs_fs_cursor *fc, struct a
  */
 bool afs_check_server_record(struct afs_fs_cursor *fc, struct afs_server *server)
 {
-	time64_t now = ktime_get_real_seconds();
-	long diff;
 	bool success;
 	int ret, retries = 0;
 
@@ -579,13 +577,16 @@ bool afs_check_server_record(struct afs_fs_cursor *fc, struct afs_server *server
 	ASSERT(server);
 
 retry:
-	diff = READ_ONCE(server->update_at) - now;
-	if (diff > 0) {
-		_leave(" = t [not now %ld]", diff);
-		return true;
-	}
+	if (test_bit(AFS_SERVER_FL_UPDATING, &server->flags))
+		goto wait;
+	if (test_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags))
+		goto update;
+	_leave(" = t [good]");
+	return true;
 
+update:
 	if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) {
+		clear_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
 		success = afs_update_server_record(fc, server);
 		clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags);
 		wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING);
@@ -593,6 +594,7 @@ bool afs_check_server_record(struct afs_fs_cursor *fc, struct afs_server *server
 		return success;
 	}
 
+wait:
 	ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING,
 			  (fc->flags & AFS_FS_CURSOR_INTR) ?
 			  TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
diff --git a/fs/afs/server_list.c b/fs/afs/server_list.c
index 888d91d195d9..f567732df5cc 100644
--- a/fs/afs/server_list.c
+++ b/fs/afs/server_list.c
@@ -51,7 +51,8 @@ struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
 		if (!(vldb->fs_mask[i] & type_mask))
 			continue;
 
-		server = afs_lookup_server(cell, key, &vldb->fs_server[i]);
+		server = afs_lookup_server(cell, key, &vldb->fs_server[i],
+					   vldb->addr_version[i]);
 		if (IS_ERR(server)) {
 			ret = PTR_ERR(server);
 			if (ret == -ENOENT ||
diff --git a/fs/afs/vlclient.c b/fs/afs/vlclient.c
index 516e9a3bb5b4..972dc5512f33 100644
--- a/fs/afs/vlclient.c
+++ b/fs/afs/vlclient.c
@@ -82,6 +82,7 @@ static int afs_deliver_vl_get_entry_by_name_u(struct afs_call *call)
 		for (j = 0; j < 6; j++)
 			uuid->node[j] = (u8)ntohl(xdr->node[j]);
 
+		entry->addr_version[n] = ntohl(uvldb->serverUnique[i]);
 		entry->nr_servers++;
 	}
 



  parent reply	other threads:[~2020-05-29 22:00 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-29 21:59 [PATCH 00/27] afs: Improvements David Howells
2020-05-29 22:00 ` [PATCH 01/27] vfs, afs, ext4: Make the inode hash table RCU searchable David Howells
2020-05-31 13:09   ` Al Viro
2020-05-31 14:20   ` David Howells
2020-05-29 22:00 ` [PATCH 02/27] rxrpc: Map the EACCES error produced by some ICMP6 to EHOSTUNREACH David Howells
2020-05-29 22:00 ` [PATCH 03/27] rxrpc: Adjust /proc/net/rxrpc/calls to display call->debug_id not user_ID David Howells
2020-05-29 22:00 ` [PATCH 04/27] afs: Always include dir in bulk status fetch from afs_do_lookup() David Howells
2020-05-29 22:00 ` David Howells [this message]
2020-05-29 22:00 ` [PATCH 06/27] afs: Split the usage count on struct afs_server David Howells
2020-05-29 22:00 ` [PATCH 07/27] afs: Actively poll fileservers to maintain NAT or firewall openings David Howells
2020-05-29 22:01 ` [PATCH 08/27] afs: Show more information in /proc/net/afs/servers David Howells
2020-05-29 22:01 ` [PATCH 09/27] afs: Make callback processing more efficient David Howells
2020-05-29 22:01 ` [PATCH 10/27] afs: Set error flag rather than return error from file status decode David Howells
2020-05-29 22:01 ` [PATCH 11/27] afs: Remove the error argument from afs_protocol_error() David Howells
2020-05-29 22:01 ` [PATCH 12/27] afs: Rename struct afs_fs_cursor to afs_operation David Howells
2020-05-29 22:01 ` [PATCH 13/27] afs: Build an abstraction around an "operation" concept David Howells
2020-05-29 22:01 ` [PATCH 14/27] afs: Don't get epoch from a server because it may be ambiguous David Howells
2020-05-29 22:01 ` [PATCH 15/27] afs: Fix handling of CB.ProbeUuid cache manager op David Howells
2020-05-29 22:02 ` [PATCH 16/27] afs: Retain more of the VLDB record for alias detection David Howells
2020-05-29 22:02 ` [PATCH 17/27] afs: Implement client support for the YFSVL.GetCellName RPC op David Howells
2020-05-29 22:02 ` [PATCH 18/27] afs: Detect cell aliases 1 - Cells with root volumes David Howells
2020-06-06  1:58   ` Kees Cook
2020-05-29 22:02 ` [PATCH 19/27] afs: Detect cell aliases 2 - Cells with no " David Howells
2020-05-29 22:02 ` [PATCH 20/27] afs: Detect cell aliases 3 - YFS Cells with a canonical cell name op David Howells
2020-05-29 22:02 ` [PATCH 21/27] afs: Add a tracepoint to track the lifetime of the afs_volume struct David Howells
2020-05-29 22:02 ` [PATCH 22/27] afs: Reorganise volume and server trees to be rooted on the cell David Howells
2020-05-29 22:02 ` [PATCH 23/27] afs: Fix the by-UUID server tree to allow servers with the same UUID David Howells
2020-05-29 22:02 ` [PATCH 24/27] afs: Fix afs_statfs() to not let the values go below zero David Howells
2020-05-29 22:03 ` [PATCH 25/27] afs: Don't use probe running state to make decisions outside probe code David Howells
2020-05-29 22:03 ` [PATCH 26/27] afs: Show more a bit more server state in /proc/net/afs/servers David Howells
2020-05-29 22:03 ` [PATCH 27/27] afs: Adjust the fileserver rotation algorithm to reprobe/retry more quickly David Howells

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