Commit 4dcd00b1 authored by Ian Kent's avatar Ian Kent Committed by Linus Torvalds
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[PATCH] autofs4: wait order fix 



It's possible for an event wait request to arive before the event
requestor.  If this happens the daemon never gets notified and autofs
hangs.

Signed-off-by: default avatarIan Kent <raven@themaw.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 945b0920

fs/autofs4/autofs_i.h

+1 −0
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ struct autofs_wait_queue { 
	char *name;

	/* This is for status reporting upon return */

	int status;

	atomic_t notified;

	atomic_t wait_ctr;

};

fs/autofs4/waitq.c

+12 −10
Original line number Diff line number Diff line
@@ -210,17 +210,8 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, 
		wq->len = len;

		wq->status = -EINTR; /* Status return if interrupted */

		atomic_set(&wq->wait_ctr, 2);

		atomic_set(&wq->notified, 1);

		up(&sbi->wq_sem);



		DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d",

			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);

		/* autofs4_notify_daemon() may block */

		if (notify != NFY_NONE) {

			autofs4_notify_daemon(sbi,wq, 

					notify == NFY_MOUNT ?

						  autofs_ptype_missing :

						  autofs_ptype_expire_multi);

		}

	} else {

		atomic_inc(&wq->wait_ctr);

		up(&sbi->wq_sem);
@@ -229,6 +220,17 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, 
			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);

	}



	if (notify != NFY_NONE && atomic_dec_and_test(&wq->notified)) {

		int type = (notify == NFY_MOUNT ?

			autofs_ptype_missing : autofs_ptype_expire_multi);



		DPRINTK(("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",

			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify));



		/* autofs4_notify_daemon() may block */

		autofs4_notify_daemon(sbi, wq, type);

	}



	/* wq->name is NULL if and only if the lock is already released */



	if ( sbi->catatonic ) {