autofs4: deal with autofs4_write/autofs4_write races
Just serialize the actual writing of packets into pipe on
a new mutex, independent from everything else in the locking
hierarchy. As soon as something has started feeding a piece
of packet into the pipe to daemon, we *want* everything else
about to try the same to wait until we are done.
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 2ba44c7..e16980b 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -225,6 +225,7 @@
sbi->min_proto = 0;
sbi->max_proto = 0;
mutex_init(&sbi->wq_mutex);
+ mutex_init(&sbi->pipe_mutex);
spin_lock_init(&sbi->fs_lock);
sbi->queues = NULL;
spin_lock_init(&sbi->lookup_lock);