knfsd: don't allocate file_locks on the stack

struct file_lock is pretty large and really ought not live on the stack.
On my x86_64 machine, they're almost 200 bytes each.

    (gdb) p sizeof(struct file_lock)
    $1 = 192

...allocate them dynamically instead.
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -4046,8 +4046,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	struct nfs4_lockowner *lock_sop = NULL;
 	struct nfs4_ol_stateid *lock_stp;
 	struct file *filp = NULL;
-	struct file_lock file_lock;
-	struct file_lock conflock;
+	struct file_lock *file_lock = NULL;
+	struct file_lock *conflock = NULL;
 	__be32 status = 0;
 	bool new_state = false;
 	int lkflg;
@@ -4117,21 +4117,28 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	if (!locks_in_grace(SVC_NET(rqstp)) && lock->lk_reclaim)
 		goto out;
 
-	locks_init_lock(&file_lock);
+	file_lock = locks_alloc_lock();
+	if (!file_lock) {
+		dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
+		status = nfserr_jukebox;
+		goto out;
+	}
+
+	locks_init_lock(file_lock);
 	switch (lock->lk_type) {
 		case NFS4_READ_LT:
 		case NFS4_READW_LT:
 			filp = find_readable_file(lock_stp->st_file);
 			if (filp)
 				get_lock_access(lock_stp, NFS4_SHARE_ACCESS_READ);
-			file_lock.fl_type = F_RDLCK;
+			file_lock->fl_type = F_RDLCK;
 			break;
 		case NFS4_WRITE_LT:
 		case NFS4_WRITEW_LT:
 			filp = find_writeable_file(lock_stp->st_file);
 			if (filp)
 				get_lock_access(lock_stp, NFS4_SHARE_ACCESS_WRITE);
-			file_lock.fl_type = F_WRLCK;
+			file_lock->fl_type = F_WRLCK;
 			break;
 		default:
 			status = nfserr_inval;
@@ -4141,17 +4148,23 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		status = nfserr_openmode;
 		goto out;
 	}
-	file_lock.fl_owner = (fl_owner_t)lock_sop;
-	file_lock.fl_pid = current->tgid;
-	file_lock.fl_file = filp;
-	file_lock.fl_flags = FL_POSIX;
-	file_lock.fl_lmops = &nfsd_posix_mng_ops;
-
-	file_lock.fl_start = lock->lk_offset;
-	file_lock.fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
-	nfs4_transform_lock_offset(&file_lock);
+	file_lock->fl_owner = (fl_owner_t)lock_sop;
+	file_lock->fl_pid = current->tgid;
+	file_lock->fl_file = filp;
+	file_lock->fl_flags = FL_POSIX;
+	file_lock->fl_lmops = &nfsd_posix_mng_ops;
+	file_lock->fl_start = lock->lk_offset;
+	file_lock->fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
+	nfs4_transform_lock_offset(file_lock);
+
+	conflock = locks_alloc_lock();
+	if (!conflock) {
+		dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
+		status = nfserr_jukebox;
+		goto out;
+	}
 
-	err = vfs_lock_file(filp, F_SETLK, &file_lock, &conflock);
+	err = vfs_lock_file(filp, F_SETLK, file_lock, conflock);
 	switch (-err) {
 	case 0: /* success! */
 		update_stateid(&lock_stp->st_stid.sc_stateid);
@@ -4162,7 +4175,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	case (EAGAIN):		/* conflock holds conflicting lock */
 		status = nfserr_denied;
 		dprintk("NFSD: nfsd4_lock: conflicting lock found!\n");
-		nfs4_set_lock_denied(&conflock, &lock->lk_denied);
+		nfs4_set_lock_denied(conflock, &lock->lk_denied);
 		break;
 	case (EDEADLK):
 		status = nfserr_deadlock;
@@ -4177,6 +4190,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		release_lockowner(lock_sop);
 	if (!cstate->replay_owner)
 		nfs4_unlock_state();
+	if (file_lock)
+		locks_free_lock(file_lock);
+	if (conflock)
+		locks_free_lock(conflock);
 	return status;
 }
 
@@ -4205,7 +4222,7 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	    struct nfsd4_lockt *lockt)
 {
 	struct inode *inode;
-	struct file_lock file_lock;
+	struct file_lock *file_lock = NULL;
 	struct nfs4_lockowner *lo;
 	__be32 status;
 	struct nfsd_net *nn = net_generic(&init_net, nfsd_net_id);
@@ -4226,15 +4243,21 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		goto out;
 
 	inode = cstate->current_fh.fh_dentry->d_inode;
-	locks_init_lock(&file_lock);
+	file_lock = locks_alloc_lock();
+	if (!file_lock) {
+		dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
+		status = nfserr_jukebox;
+		goto out;
+	}
+	locks_init_lock(file_lock);
 	switch (lockt->lt_type) {
 		case NFS4_READ_LT:
 		case NFS4_READW_LT:
-			file_lock.fl_type = F_RDLCK;
+			file_lock->fl_type = F_RDLCK;
 		break;
 		case NFS4_WRITE_LT:
 		case NFS4_WRITEW_LT:
-			file_lock.fl_type = F_WRLCK;
+			file_lock->fl_type = F_WRLCK;
 		break;
 		default:
 			dprintk("NFSD: nfs4_lockt: bad lock type!\n");
@@ -4244,25 +4267,27 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 
 	lo = find_lockowner_str(inode, &lockt->lt_clientid, &lockt->lt_owner);
 	if (lo)
-		file_lock.fl_owner = (fl_owner_t)lo;
-	file_lock.fl_pid = current->tgid;
-	file_lock.fl_flags = FL_POSIX;
+		file_lock->fl_owner = (fl_owner_t)lo;
+	file_lock->fl_pid = current->tgid;
+	file_lock->fl_flags = FL_POSIX;
 
-	file_lock.fl_start = lockt->lt_offset;
-	file_lock.fl_end = last_byte_offset(lockt->lt_offset, lockt->lt_length);
+	file_lock->fl_start = lockt->lt_offset;
+	file_lock->fl_end = last_byte_offset(lockt->lt_offset, lockt->lt_length);
 
-	nfs4_transform_lock_offset(&file_lock);
+	nfs4_transform_lock_offset(file_lock);
 
-	status = nfsd_test_lock(rqstp, &cstate->current_fh, &file_lock);
+	status = nfsd_test_lock(rqstp, &cstate->current_fh, file_lock);
 	if (status)
 		goto out;
 
-	if (file_lock.fl_type != F_UNLCK) {
+	if (file_lock->fl_type != F_UNLCK) {
 		status = nfserr_denied;
-		nfs4_set_lock_denied(&file_lock, &lockt->lt_denied);
+		nfs4_set_lock_denied(file_lock, &lockt->lt_denied);
 	}
 out:
 	nfs4_unlock_state();
+	if (file_lock)
+		locks_free_lock(file_lock);
 	return status;
 }
 
@@ -4272,7 +4297,7 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 {
 	struct nfs4_ol_stateid *stp;
 	struct file *filp = NULL;
-	struct file_lock file_lock;
+	struct file_lock *file_lock = NULL;
 	__be32 status;
 	int err;
 						        
@@ -4294,22 +4319,29 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		status = nfserr_lock_range;
 		goto out;
 	}
-	locks_init_lock(&file_lock);
-	file_lock.fl_type = F_UNLCK;
-	file_lock.fl_owner = (fl_owner_t)lockowner(stp->st_stateowner);
-	file_lock.fl_pid = current->tgid;
-	file_lock.fl_file = filp;
-	file_lock.fl_flags = FL_POSIX; 
-	file_lock.fl_lmops = &nfsd_posix_mng_ops;
-	file_lock.fl_start = locku->lu_offset;
-
-	file_lock.fl_end = last_byte_offset(locku->lu_offset, locku->lu_length);
-	nfs4_transform_lock_offset(&file_lock);
+	file_lock = locks_alloc_lock();
+	if (!file_lock) {
+		dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
+		status = nfserr_jukebox;
+		goto out;
+	}
+	locks_init_lock(file_lock);
+	file_lock->fl_type = F_UNLCK;
+	file_lock->fl_owner = (fl_owner_t)lockowner(stp->st_stateowner);
+	file_lock->fl_pid = current->tgid;
+	file_lock->fl_file = filp;
+	file_lock->fl_flags = FL_POSIX;
+	file_lock->fl_lmops = &nfsd_posix_mng_ops;
+	file_lock->fl_start = locku->lu_offset;
+
+	file_lock->fl_end = last_byte_offset(locku->lu_offset,
+						locku->lu_length);
+	nfs4_transform_lock_offset(file_lock);
 
 	/*
 	*  Try to unlock the file in the VFS.
 	*/
-	err = vfs_lock_file(filp, F_SETLK, &file_lock, NULL);
+	err = vfs_lock_file(filp, F_SETLK, file_lock, NULL);
 	if (err) {
 		dprintk("NFSD: nfs4_locku: vfs_lock_file failed!\n");
 		goto out_nfserr;
@@ -4323,6 +4355,8 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 out:
 	if (!cstate->replay_owner)
 		nfs4_unlock_state();
+	if (file_lock)
+		locks_free_lock(file_lock);
 	return status;
 
 out_nfserr: