[PATCH 1/2] nfsd: fix version-setting regression on old kernels

J. Bruce Fields
2010-01-27T22:24:31Z

/proc/fs/nfsd/versions was extended to allow turning on/off minor
versions by echoing "+4.1" or "-4.1" to /proc/fs/nsfd/versions.

Unfortunately, pre-2.6.30 kernels just stop parsing at first non-digit,
so "-4.1" is interpreted as "-4". If new nfs-utils (on old kernel)
writes "+2", "+3", "+4", then "-4.1", result therefore is to turn off
4.1.

Given that historical behavior, it may have been a mistake to extend the
interface the way we did; but at this point we're probably stuck with
it. So, just reverse the order we write versions in.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
---
utils/nfsd/nfssvc.c | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/utils/nfsd/nfssvc.c b/utils/nfsd/nfssvc.c
index b8028bb..7bbbaba 100644
--- a/utils/nfsd/nfssvc.c
+++ b/utils/nfsd/nfssvc.c
@@ -238,17 +238,17 @@ nfssvc_setvers(unsigned int ctlbits, int minorvers4)
if (fd < 0)
return;

+ n = minorvers4 >= 0 ? minorvers4 : -minorvers4;
+ if (n >= NFSD_MINMINORVERS4 && n <= NFSD_MAXMINORVERS4)
+ off += snprintf(ptr+off, sizeof(buf) - off, "%c4.%d",
+ minorvers4 > 0 ? '+' : '-',
+ n);
for (n = NFSD_MINVERS; n <= NFSD_MAXVERS; n++) {
if (NFSCTL_VERISSET(ctlbits, n))
off += snprintf(ptr+off, sizeof(buf) - off, "+%d ", n);
else
off += snprintf(ptr+off, sizeof(buf) - off, "-%d ", n);
}
- n = minorvers4 >= 0 ? minorvers4 : -minorvers4;
- if (n >= NFSD_MINMINORVERS4 && n <= NFSD_MAXMINORVERS4)
- off += snprintf(ptr+off, sizeof(buf) - off, "%c4.%d",
- minorvers4 > 0 ? '+' : '-',
- n);
xlog(D_GENERAL, "Writing version string to kernel: %s", buf);
snprintf(ptr+off, sizeof(buf) - off, "\n");
if (write(fd, buf, strlen(buf)) != strlen(buf))
--
1.6.3.3