diff options
authorRick Macklem <rmacklem@FreeBSD.org>2024-03-16 01:04:37 +0000
committerRick Macklem <rmacklem@FreeBSD.org>2024-03-30 00:58:33 +0000
commitb525301850f2e39389bdad45fc327b5f8708129d (patch)
parentd9d05e65c1f7dd5c39a180ebc1f806482cb875e0 (diff)
nfsd: Add a sysctl to limit NFSv4.2 Copy RPC size
NFSv4.2 supports a Copy operation, which avoids file data being read to the client and then written back to the server, if both input and output files are on the same NFSv4.2 mount for copy_file_range(2). Unfortunately, this Copy operation can take a long time under certain circumstances. If this occurs concurrently with a RPC that requires an exclusive lock on the nfsd such as ExchangeID done for a new mount, the result can be an nfsd "stall" until the Copy completes. This patch adds a sysctl that can be set to limit the size of a Copy operation or, if set to 0, disable Copy operations. The use of this sysctl and other ways to avoid Copy operations taking too long will be documented in the nfsd.4 man page by a separate commit. (cherry picked from commit 748f56c53f4286e0b140c1b779ff8ade1cf4fec9)
1 files changed, 14 insertions, 2 deletions
diff --git a/sys/fs/nfsserver/nfs_nfsdserv.c b/sys/fs/nfsserver/nfs_nfsdserv.c
index 3daee65ab83a..899e88508b60 100644
--- a/sys/fs/nfsserver/nfs_nfsdserv.c
+++ b/sys/fs/nfsserver/nfs_nfsdserv.c
@@ -97,6 +97,9 @@ static bool nfsrv_doallocate = false;
SYSCTL_BOOL(_vfs_nfsd, OID_AUTO, enable_v42allocate, CTLFLAG_RW,
&nfsrv_doallocate, 0,
"Enable NFSv4.2 Allocate operation");
+static uint64_t nfsrv_maxcopyrange = SSIZE_MAX;
+SYSCTL_U64(_vfs_nfsd, OID_AUTO, maxcopyrange, CTLFLAG_RW,
+ &nfsrv_maxcopyrange, 0, "Max size of a Copy so RPC times reasonable");
* This list defines the GSS mechanisms supported.
@@ -5598,10 +5601,11 @@ nfsrvd_copy_file_range(struct nfsrv_descript *nd, __unused int isdgram,
void *rl_rcookie, *rl_wcookie;
rl_rcookie = rl_wcookie = NULL;
- if (nfsrv_devidcnt > 0) {
+ if (nfsrv_maxcopyrange == 0 || nfsrv_devidcnt > 0) {
* For a pNFS server, reply NFSERR_NOTSUPP so that the client
* will do the copy via I/O on the DS(s).
+ * If vfs.nfsd.maxcopyrange set to 0, disable Copy.
nd->nd_repstat = NFSERR_NOTSUPP;
goto nfsmout;
@@ -5764,7 +5768,15 @@ nfsrvd_copy_file_range(struct nfsrv_descript *nd, __unused int isdgram,
nd->nd_repstat = error;
- xfer = len;
+ /*
+ * Do the actual copy to an upper limit of vfs.nfsd.maxcopyrange.
+ * This size limit can be set to limit the time a copy RPC will
+ * take.
+ */
+ if (len > nfsrv_maxcopyrange)
+ xfer = nfsrv_maxcopyrange;
+ else
+ xfer = len;
if (nd->nd_repstat == 0) {
nd->nd_repstat = vn_copy_file_range(vp, &inoff, tovp, &outoff,
&xfer, COPY_FILE_RANGE_TIMEO1SEC, nd->nd_cred, nd->nd_cred,