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mount_nfs: Warn that intr, soft are not safe for NFSv4

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If the "intr" and/or "soft" mount options are used for
NFSv4 mounts, the protocol can be broken when the
operation returns without waiting for the RPC reply.
The likelyhood of failure increases for NFSv4.1/4.2
mounts, since the session slot will be broken when
an RPC reply is not processed.

This is mentioned in the BUGS section of "man mount_nfs",
but more needs to be done.  This patch adds code that
generates a warning message when the mount is done.

PR: 260011
Reviewed by:	emaste
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D35407
This commit is contained in:
Rick Macklem 2022-07-01 14:43:17 -07:00
parent ea5b2d6242
commit c0d14b0220
1 changed files with 14 additions and 0 deletions
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14
sbin/mount_nfs/mount_nfs.c
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@ -73,6 +73,7 @@ __FBSDID("$FreeBSD$");
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -160,7 +161,9 @@ main(int argc, char *argv[])
char mntpath[MAXPATHLEN], errmsg[255];
char hostname[MAXHOSTNAMELEN + 1], gssn[MAXHOSTNAMELEN + 50];
const char *gssname, *nmount_errstr;
bool softintr;
softintr = false;
iov = NULL;
iovlen = 0;
memset(errmsg, 0, sizeof(errmsg));
@ -210,6 +213,7 @@ main(int argc, char *argv[])
case 'i':
printf("-i deprecated, use -o intr\n");
build_iovec(&iov, &iovlen, "intr", NULL, 0);
softintr = true;
break;
case 'L':
printf("-L deprecated, use -o nolockd\n");
@ -366,6 +370,10 @@ main(int argc, char *argv[])
"value -- %s", val);
}
pass_flag_to_nmount=0;
} else if (strcmp(opt, "soft") == 0) {
softintr = true;
} else if (strcmp(opt, "intr") == 0) {
softintr = true;
}
if (pass_flag_to_nmount) {
build_iovec(&iov, &iovlen, opt,
@ -395,6 +403,7 @@ main(int argc, char *argv[])
case 's':
printf("-s deprecated, use -o soft\n");
build_iovec(&iov, &iovlen, "soft", NULL, 0);
softintr = true;
break;
case 'T':
nfsproto = IPPROTO_TCP;
@ -433,6 +442,11 @@ main(int argc, char *argv[])
/* NOTREACHED */
}
/* Warn that NFSv4 mounts only work correctly as hard mounts. */
if (mountmode == V4 && softintr)
warnx("Warning, options soft and/or intr cannot be safely used"
" for NFSv4. See the BUGS section of mount_nfs(8)");
spec = *argv++;
mntname = *argv;