nfsd: notify_change needs elevated write count

Looks like this bug has been here since these write counts were
introduced, not sure why it was just noticed now.

Thanks also to Jan Kara for pointing out the problem.

Cc: stable@vger.kernel.org
Reported-by: Matthew Rahtz <mrahtz@rapitasystems.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2014-02-24 14:59:47 -05:00
parent a11fcce154
commit 9f67f18993

View File

@ -404,6 +404,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
umode_t ftype = 0;
__be32 err;
int host_err;
bool get_write_count;
int size_change = 0;
if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME | ATTR_SIZE))
@ -411,10 +412,18 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
if (iap->ia_valid & ATTR_SIZE)
ftype = S_IFREG;
/* Callers that do fh_verify should do the fh_want_write: */
get_write_count = !fhp->fh_dentry;
/* Get inode */
err = fh_verify(rqstp, fhp, ftype, accmode);
if (err)
goto out;
if (get_write_count) {
host_err = fh_want_write(fhp);
if (host_err)
return nfserrno(host_err);
}
dentry = fhp->fh_dentry;
inode = dentry->d_inode;