NFS: Ensure we always hold the BKL when dereferencing inode->i_flock
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 6e094e9..0b2a19b 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -847,12 +847,19 @@
struct file_lock *fl;
int status = 0;
+ if (inode->i_flock == NULL)
+ return 0;
+
+ /* Guard against delegation returns and new lock/unlock calls */
down_write(&nfsi->rwsem);
+ /* Protect inode->i_flock using the BKL */
+ lock_kernel();
for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
continue;
if (nfs_file_open_context(fl->fl_file)->state != state)
continue;
+ unlock_kernel();
status = ops->recover_lock(state, fl);
switch (status) {
case 0:
@@ -875,7 +882,9 @@
/* kill_proc(fl->fl_pid, SIGLOST, 1); */
status = 0;
}
+ lock_kernel();
}
+ unlock_kernel();
out:
up_write(&nfsi->rwsem);
return status;