From 640372388086834e56fe505e287c42ff1580bbd6 Mon Sep 17 00:00:00 2001 From: Rick Macklem Date: Wed, 25 Jan 2012 00:22:53 +0000 Subject: [PATCH] If a mount -u is done to either NFS client that switches it from TCP to UDP and the rsize/wsize/readdirsize is greater than NFS_MAXDGRAMDATA, it is possible for a thread doing an I/O RPC to get stuck repeatedly doing retries. This happens because the RPC will use a resize/wsize/readdirsize that won't work for UDP and, as such, it will keep failing indefinitely. This patch returns an error for this case, to avoid the problem. A discussion on freebsd-fs@ seemed to indicate that returning an error was preferable to silently ignoring the "udp"/"mntudp" option. This problem was discovered while investigating a problem reported by pjd@ via email. MFC after: 2 weeks --- sys/fs/nfsclient/nfs_clvfsops.c | 17 +++++++++++++++++ sys/nfsclient/nfs_vfsops.c | 17 +++++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/sys/fs/nfsclient/nfs_clvfsops.c b/sys/fs/nfsclient/nfs_clvfsops.c index ccb35f178bec..5ddfa2790e95 100644 --- a/sys/fs/nfsclient/nfs_clvfsops.c +++ b/sys/fs/nfsclient/nfs_clvfsops.c @@ -989,6 +989,23 @@ nfs_mount(struct mount *mp) error = EIO; goto out; } + + /* + * Cannot switch to UDP if current rsize/wsize/readdirsize is + * too large, since there may be an I/O RPC in progress that + * will get retried after the switch to the UDP socket. These + * retries will fail over and over and over again. + */ + if (args.sotype == SOCK_DGRAM && + (nmp->nm_rsize > NFS_MAXDGRAMDATA || + nmp->nm_wsize > NFS_MAXDGRAMDATA || + nmp->nm_readdirsize > NFS_MAXDGRAMDATA)) { + vfs_mount_error(mp, + "old rsize/wsize/readdirsize greater than UDP max"); + error = EINVAL; + goto out; + } + /* * When doing an update, we can't change version, * security, switch lockd strategies or change cookie diff --git a/sys/nfsclient/nfs_vfsops.c b/sys/nfsclient/nfs_vfsops.c index fafc2537ba6f..e43c048f517b 100644 --- a/sys/nfsclient/nfs_vfsops.c +++ b/sys/nfsclient/nfs_vfsops.c @@ -1106,6 +1106,23 @@ nfs_mount(struct mount *mp) error = EIO; goto out; } + + /* + * Cannot switch to UDP if current rsize/wsize/readdirsize is + * too large, since there may be an I/O RPC in progress that + * will get retried after the switch to the UDP socket. These + * retries will fail over and over and over again. + */ + if (args.sotype == SOCK_DGRAM && + (nmp->nm_rsize > NFS_MAXDGRAMDATA || + nmp->nm_wsize > NFS_MAXDGRAMDATA || + nmp->nm_readdirsize > NFS_MAXDGRAMDATA)) { + vfs_mount_error(mp, + "old rsize/wsize/readdirsize greater than UDP max"); + error = EINVAL; + goto out; + } + /* * When doing an update, we can't change from or to * v3, switch lockd strategies or change cookie translation