fs: remove mandatory file locking support

We added CONFIG_MANDATORY_FILE_LOCKING in 2015, and soon after turned it
off in Fedora and RHEL8. Several other distros have followed suit.

I've heard of one problem in all that time: Someone migrated from an
older distro that supported "-o mand" to one that didn't, and the host
had a fstab entry with "mand" in it which broke on reboot. They didn't
actually _use_ mandatory locking so they just removed the mount option
and moved on.

This patch rips out mandatory locking support wholesale from the kernel,
along with the Kconfig option and the Documentation file. It also
changes the mount code to ignore the "mand" mount option instead of
erroring out, and to throw a big, ugly warning.

Signed-off-by: Jeff Layton <jlayton@kernel.org>

1 files changed, 1 insertions, 22 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index a224a5e23cc1..92e77f92268a 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -333,7 +333,6 @@ nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		struct iattr *iap)
 {
 	struct inode *inode = d_inode(fhp->fh_dentry);
-	int host_err;
 
 	if (iap->ia_size < inode->i_size) {
 		__be32 err;
@@ -343,20 +342,7 @@ nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		if (err)
 			return err;
 	}
-
-	host_err = get_write_access(inode);
-	if (host_err)
-		goto out_nfserrno;
-
-	host_err = locks_verify_truncate(inode, NULL, iap->ia_size);
-	if (host_err)
-		goto out_put_write_access;
-	return 0;
-
-out_put_write_access:
-	put_write_access(inode);
-out_nfserrno:
-	return nfserrno(host_err);
+	return nfserrno(get_write_access(inode));
 }
 
 /*
@@ -750,13 +736,6 @@ __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 	err = nfserr_perm;
 	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
 		goto out;
-	/*
-	 * We must ignore files (but only files) which might have mandatory
-	 * locks on them because there is no way to know if the accesser has
-	 * the lock.
-	 */
-	if (S_ISREG((inode)->i_mode) && mandatory_lock(inode))
-		goto out;
 
 	if (!inode->i_fop)
 		goto out;